JP2008500724A - Vertical color filter sensor group and method for manufacturing semiconductor integrated circuit - Google Patents

Abstract

A high-sensitivity image sensor that can reduce the area of an image sensor, achieve a fine and simple sensor circuit, and can be easily manufactured.
A formed vertical color filter sensor group having at least two vertically stacked photosensitive sensors is formed on a semiconductor substrate by a semiconductor integrated circuit manufacturing process. Another feature of the present invention is a group of vertical color filter sensors and a method of manufacturing such a group of vertical color filter sensors and their arrays. In some embodiments, the sensor group is a block of solid material having a readout surface. At least two vertically stacked sensors are formed in this block, and a trench contact is disposed between one of the sensors and the readout surface.
[Selection] Figure 15H

Description

  The present invention relates to a group of photosensitive sensors including vertically stacked sensors. In each group, the semiconductor material chromatically filters incident electromagnetic radiation. (Optically, other materials also filter their radiation.) Each sensor simultaneously detects a different wavelength band. The invention also relates to an arrangement of such sensor groups, each sensor group being arranged at a different pixel location.

  The expressions “filter” and “color filter” are used herein broadly (including claims) to indicate elements that reflect or selectively transmit at least one wavelength band of electromagnetic radiation incident thereon. Used interchangeably in meaning. For example, one type of filter is a dichroic mirror that transmits radiation in a first wavelength band and reflects radiation in a second wavelength band. Examples of filters include short wave pass filters, long wave pass filters, and band pass filters.

  The term “radiation” is used herein to denote electromagnetic radiation.

  The expression “top sensor” here refers to the group of sensors that the incident radiation reaches in the sensor group before reaching any other sensor group. The expression sensor in a sensor group “stacked vertically” means that one of the sensors is the top sensor of the group, and at least one axis that extends through all the sensors. (Sometimes called the "vertical axis"). As described below, vertical color filter (“VCF”) sensor groups embodying the present invention are preferred, with the top sensor of the group having a normal axis (eg, at least substantially planar). It includes a vertically stacked sensor configured to have a top surface defining. When radiation propagating along the vertical axis of the group is incident on the group, the radiation is at an angle of incidence of less than about 30 degrees with respect to the standard (normal) axis (eg, radiation is normally incident on the group). Incident into the top sensor.

  Two elements included in a structure with a vertical axis separated “laterally” (ie “horizontally”) have an axis parallel to the vertical axis that extends between the elements but does not intersect any element Is used here.

  The expression “constituting” an element is used herein (including claims) to indicate that the item is, or contains, the element.

  MOS active pixel sensors are well known in the art. Multiple wavelength band active pixel sensor arrays are also well known in the art. One type of multi-wavelength band active pixel sensor array uses red, green, and blue sensors that are arranged horizontally in a pattern at or near the semiconductor surface. Such sensors have the advantage that they occupy a relatively large area per resolution element, both stretched flat. Furthermore, color image reconstruction from such a sensor array can be enhanced on a computer, but produces unnatural, defective, and poorly resolved images.

  Another type of multi-wavelength band active pixel sensor array uses a group of sensors, each including vertically arranged sensors. The use of an early multi-wavelength band active pixel sensor group to detect visible and infrared radiation is disclosed in Karl US Pat. No. 4,238,760, where the first in surface n-type epitaxial is The diode is sensitive to visible light and the second diode (including the buried p-type region in the underlying n-type substrate) is sensitive to infrared light. Karl teaches that the contacts to the buried diodes are made using a deep diffusion process that “similar to the common sub-thin diffusion collector contact diffusion in bipolar IC processes and to reduce the parameter Rcs”. Karl also discloses an embodiment. A V-groove contact (made by a process that includes an etching step through an n-type epitaxial region) provides a contact to the buried p-type region. The disclosed device has a size of 4 mils.

  The device disclosed in the Karl patent has several drawbacks, most notably its large area and inadequate for the image sensor density of modern imaging systems. This technology used for contact formation with embedded infrared sensing diodes is not appropriate for the latest imaging technology and expansion to three-color sensors.

  Merrill US Pat. No. 5,965,875 discloses a group of sensors in which three colors, visible light, and structure are provided using a triple well CMOS process, where blue, green, and red sensitive PN junctions are provided. The imagers (imaging devices) are arranged at different depths relative to the surface of the semiconductor substrate on which the imagers (imaging devices) are made. This three-color sensor group enables the production of a high-density imaging array because three colors are sensed over the same area in the image plane. However, the structure has several drawbacks. First, this sensor group uses a central green sensing PN junction with reverse polarity, requires a correction circuit and voltage range, and in addition to the normal NMOS transistor to sense and read the green channel, if possible a PMOS transistor Including. This need increases the sensor area and complicates the support circuitry in the detector that includes the sensor group. This additional circuit complexity makes it difficult to create an image sensor array (disclosed here) with flexible color readout capability and achieves the small sensor size required by many modern electronic imaging applications. Make it impossible.

  US Pat. No. 6,111,300 to Cao et al. Discloses a PIN photodiode that attempts to collect blue light and two additional semiconductor junction diodes (vertical from the PIN photodiode) in a semiconductor substrate to detect green and red light. Disclosed is a color active pixel sensor using (spaced in direction). The disadvantages of this sensor are that it is difficult to manufacture, non-standard manufacturing technology, the use of structures that prohibit high density sensors (in one array), and the ability to select different colors for readout. And no detection of more than two colors using a monolithic semiconductor substrate.

  Findlater et al. ("CMOS Image Sensor Using Double Junction Photodiode" by Findrater, Renshaw, Reiner in IEEE Electronic Device Science (2001), 2001 IEEE Workshop on Charge Coupled Devices and High Resolution Image Sensors) is an organic An active pixel sensor using a double junction photodiode associated with a filter overlay is disclosed. Each double junction photodiode includes a top and bottom p-type layer with an n-type layer therebetween. The n-type layer forms the cathode of the first photodiode. The bottom p-type layer forms the anode of the second photodiode. The first photodiode is coupled to the first readout circuit. The second photodiode is coupled to the second readout circuit. The mosaic of cyan and yellow filters is superimposed on the array of sensors so that in each column of the array, even sensors receive radiation in the first wavelength band (blue and green) and even sensors Receive radiation in the second wavelength band (red and green). The performance of such sensor arrays is due to the poor color response of double junction photodiodes, and the n-well (which makes sensor designs very sensitive to nonlinear crosstalk between color channels) cathodes of both photodiodes. Limited by the fact that forms. In addition, the authors address process / manufacturing constraints that limit non-uniformity and its performance and potential benefits of this design.

Means for Solving the Invention

  Several types of vertical color filter (“VCF”) sensor groups and methods for manufacturing them are described in US patent application 09 / 884,863 (application June 18, 2001) and US patent application 10 / 103,304 (application March 2002). 20th). The VCF sensor group includes at least two light sensitive sensors stacked vertically with respect to each other (with or without non-sensor material between proximity sensors). Each sensor in the VCF sensor group has a different spectral sensitivity (response). Typically, each sensor has a spectral sensitivity that reaches the peak at different wavelengths. In some embodiments, the VCF sensor group (or one or more of those sensors) includes a filter that does not function as a sensor.

  The VCF sensor group senses photons (photons) of at least two wavelength bands simultaneously in the same area of the image plane. In contrast, the temporal sequential photon sensing method does not perform photon sensing simultaneously for all wavelength bands. Sensing performed by a group of VCF sensors included in the imager occurs in a region of the imager (when the imager looks vertically), and photons are separated by wavelength as a function of depth to the sensor group.

  Usually, each sensor detects photons in different wavelength bands. (For example, one sensor detects more photons in the “blue” wavelength band than each other sensor. The second sensor detects more photons in the “green” wavelength band than each other sensor. In addition, the third sensor detects more photons in the “red” wavelength band than each other sensor.) However, the sensor group usually means that multiple sensors detect photons of the same wavelength. Have some "crosstalk".

  The VCF sensor group can be used for various image processing. In the preferred embodiment, they are digital still cameras (DSC). However, they can be used in many other systems, such as linear imagers, video cameras, and machine vision devices.

  The VCF sensor group uses the properties of at least one semiconductor material to detect incident photons and to selectively detect incident photons of different wavelengths at different depths of the group. Different wavelengths can be detected by vertically stacking the sensor layers of the sensor group in combination with a change in optical absorption depth with wavelength in the semiconductor material. The cost of manufacturing the VCF sensor group is substantially reduced. The VCF sensor group does not require an external color filter (conventionally used in a color image sensor) and is different from the sensor itself (the sensor itself is made from a semiconductor material that provides the filter function by itself). Do not need. However, in some embodiments of the present invention, the VCF sensor group includes (or is used with a color filter) a different color filter than the sensor itself. The spectral sensitivity of VCF color sensors is usually much more stable to external factors such as temperature and other environmental factors (present during or after manufacture) than traditional color sensors with non-semiconductor-based filters And not sensitive.

  The VCF sensor group is preferably formed on a substrate (preferably a semiconductor substrate), doped to collect photoexcited carriers (carriers) (preferably negative electrons) of a first polarity and / or Or it includes a plurality of vertical stack sensors (eg, sensor layers) made by applying a bias. The sensor includes one or more reference layers (or one or more reference layers that allow multiple sets of sensors to be created to collect and carry out photoexcited carriers (preferably holes) of opposite polarity. Separated). The sensor has different spectral sensitivities based on different depths of the sensor group and other parameters including doping level and bias conditions. During operation, the sensors are individually connected to bias and active pixel readout circuitry. The VCF sensor groups and their manufacturing methods are more fully described in the above-cited US patent application 09 / 884,863 and US patent application 10 / 103,304.

  The array of VCF sensor groups can be modified by placing a pattern of color filters on the array described in US patent application 10 / 103,304. Using a filter made from a single filter material and placed on a collection of sensor groups, an array with three sensors per sensor group (with signals from different selected collections of sensor groups in the array) It is operable to detect radiation in four, five, or six different wavelength bands (by reading out). This can improve color accuracy. Any of many types of filters can be used, as in some conventional color image sensors, including one or more organic colored filters and integrated with the sensor group by the semiconductor integrated circuit manufacturing process An interference filter that is a stack of alternating layers of polysilicon, oxide and nitride to absorb short wavelengths, or to form spectral sensitivity by interference effects Another interference filter).

(Brief description of the present invention)
In one stage of the embodiment, the present invention is a group of vertical color filter (VCF) sensors, formed on a substrate (preferably a semiconductor substrate) by a semiconductor integrated circuit manufacturing process, and at least two vertically stacked photosensitive layers. Includes sensors. Another aspect of the present invention is an array of such vertical color filter sensor groups, and a method for manufacturing such vertical color filter sensor groups and these arrays.

  In a preferred embodiment, the VCF sensor group is a block of solid material with a readout surface. At least two vertically stacked sensors are formed in this block, each sensor having a different spectral sensitivity, and the sensor includes a layer of semiconductor material and is made to be biased to function as a photodiode. The sensor group also includes a trench contact between one of the sensors and the readout surface.

  In other preferred embodiments, the VCF sensor group is a block of solid material having a top surface and a bottom surface through which the sensed radiation can propagate. At least two vertically stacked sensors are formed in the block, each sensor having a different spectral sensitivity, the sensor includes a layer of semiconductor material, and the sensor is biased to function as a photodiode. Made. The sensor group also includes a contact between at least one of the sensors and the bottom surface and at least one transistor formed on the bottom surface. Preferably, the transistor is formed on the bottom surface by a semiconductor integrated circuit manufacturing process. Bias and readout circuitry can be coupled to this transistor.

  In another preferred embodiment, the present invention is a method of manufacturing a vertical color filter sensor group on a semiconductor substrate, including the formation of a first epitaxial layer, and a first of plug contacts in the first epitaxial layer. After forming the first portion of the plug contact by performing ion implantation to form the portion, a second epitaxial layer is formed on the first epitaxial layer, and the second epitaxial layer of the plug contact is further formed in the second epitaxial layer. Ion implantation is performed to form this portion. In another embodiment, the present invention is a group of VCF sensors that include plug contacts formed by such methods. Preferably, each ion implanted substrate has a diffusion coefficient that is significantly lower than the diffusion coefficient of phosphorus. For example, the first epitaxial layer and the second epitaxial layer consist essentially of p-type silicon, and the ion implantation material is arsenic.

  In another embodiment, the present invention is an array of VCF sensor groups formed on a semiconductor substrate having a trench or isolation region between each sensor group.

  In other embodiments, the VCF sensor group is formed on a semiconductor substrate having a first polarity and includes at least two vertically stacked sensors. Each sensor includes a semiconductor substrate carrier collection layer having a second polarity (opposite to the first polarity) and collects photoexcited carriers of the second polarity when biased to function as a photodiode. Made for. The first sensor includes a first reference volume (portion) of semiconductor material having a first polarity, and the second sensor includes a second reference volume of semiconductor material having a first polarity. A first reference volume and a second reference volume exist between the carrier collection layer of the first sensor and the second sensor, and when the sensor is biased to function as a photodiode, It is formed to collect and carry out polar photoexcited carriers. The sensor group also has a first polarity between the first reference volume and the second reference volume, but is more heavily doped than either the first reference volume or the second reference volume, Includes a separation layer of semiconductor material.

  Another aspect of the invention is an image detector that includes at least one array of VCF sensor groups and circuitry for converting photoexcited carriers generated in the sensors into electrical signals.

  Those skilled in the art will recognize that the following description of the present invention is illustrative only and is not limited in any way. Other embodiments of the invention will be readily suggested to one of ordinary skill in the art having the benefit of this disclosure.

  Most of the manufacturing processes described here assume a sensor made from crystalline silicon. However, this method (or a clear improvement for those skilled in the art) usually also applies to sensors made from other semiconductor materials or materials. Each sensor in the VCF sensor group senses a photon by converting the energy of the photon directly or indirectly to an electron-hole pair. This occurs in semiconducting materials. VCF sensor groups are typically performed so that the output of each sensor in this group exhibits a different wavelength band of incident radiation. The radiation reaching each sensor in the VCF sensor group has a different wavelength intensity spectrum due to the filtering action of the material forming the sensor group. As a result, all the sensors in the VCF sensor group are equivalent, and each sensor can output an output indicating a different wavelength band. However, in some embodiments, the sensors in the VCF sensor group are not necessarily all equivalent (eg, they are not necessarily all composed of the same material or the same combination of materials) and are predetermined. Each structure and configuration is determined to optimize or improve the performance of the sensor group for a given application. For example, sensors that have relatively high absorptance up to a predetermined range of wavelengths (ie, relatively high absorptance in such a range) and low absorptance at other wavelengths are different to form a VCF sensor group. It can be stacked vertically (longitudinal) with sensors made from other materials with spectral sensitivity.

  The color output for a digital still camera (DSC) needs to sense a minimum of three spectral bands due to the three color characteristics of the human visual system.

  As a result, to sense three different spectral bands, the VCF sensor group of the present invention (each comprising a semiconductor material) also has many embodiments with three vertically stacked sensors. VCF sensor groups with two vertically stacked sensors rather than three vertically stacked sensors are useful in other applications such as the simultaneous detection of visible and infrared radiation described in US Pat. No. 4,581,625 and US Pat. No. 4,677,289 It is. Some embodiments of the VCF sensor group of the present invention have more than two vertically stacked sensors because they are more useful for sensing than three spectral regions. Extra overhead from additional spectral regions can be used to provide a more accurate representation of the color of the object. Since more spectral data is available, the accuracy of the color representation is potentially improved.

  In an embodiment of the VCF sensor group of the present invention, each sensor is comprised of two layers of semiconductor material (including a sensor including adjacent portions of layer X01 and layer X09 in FIG. 2), or (layer X02 and layer X09 in FIG. 2). And a sensor that includes a proximity portion of X10), including a junction between the sensors of each two adjacent layers (eg, a “pn” junction or a heterojunction), and the sensor One of the layers is a carrier collection element having a contact portion (which facilitates bias and circuit readout). During normal operation, each sensor layer moves photoexcited carriers through the at least one depletion region to the contact to create a photocharge signal available at the contact portion. In a typical embodiment of the VCF sensor group, this group includes a material that can absorb photons (eg, the semiconductor material of layer X09 in FIG. 2 that does not belong to the depletion region X04 or the depletion region X05), and this Such absorption is likely to generate a charge that is detected by the readout circuit, where photoexcited carriers can move (possibly important) towards either of at least two different carrier collection elements. . Usually, all the layers of the VCF sensor group are made of a semiconductor material, but this is not necessarily the case.

FIG. 1 is a graph of the intensity of electromagnetic radiation in crystalline silicon (relative to its incident intensity I ₀ ) as a function of silicon depth for wavelengths 450 nm, 550 nm, and 650 nm. FIG. 3 shows the position of the layers of the sensor group of FIG. 2 overlaid (overlaid) on the wavelength 450 nm (curve A), 550 nm (curve B), and 650 nm (curve C), and the depth of silicon. Is a graph of the absorption rate of electromagnetic radiation in crystalline silicon (relative to its incident intensity I ₀ ) as a function of The graphs of FIGS. 1 and 3 are derived from the same data. Each curve in FIG. 3 uses its “nth” difference value, which is the difference between the “(n + 1) th” data and the “nth” data of the corresponding curve in FIG. Plot the difference values. The intensity of radiation (with a given wavelength) as a function of depth in many semiconductors other than silicon is a function similar to that plotted in FIG. FIG. 1 shows (for each wavelength) the relative intensity of the radiation (ratio I / I ₀ , where “I” is the intensity at the depth “x” of silicon and “I ₀ ” is the incident intensity): It shows that photons are absorbed by silicon and therefore decrease with increasing depth. FIGS. 1 and 3 show that relatively many blue light (450 nm) photons are absorbed near the surface rather than being long wavelength photons, and that at any depth of silicon, blue light This means that there are more green light (550nm) photons than green photons, and more red light (650nm) photons than green light (red light, green For light and blue light photons, the incident intensities are assumed to be equal).

  Each of the three curves in FIG. 1 (and FIG. 3) shows that the intensity drops exponentially with increasing depth, and further the measured behavior of light in crystalline silicon exposed to normal doping and processing. based on. The exact shape of each curve depends on the doping and process parameters. There are only slight differences between curves that assume different combinations of doping and / or process parameters. It is well known that the absorption of photons of different wavelengths by a semiconductor depends on the semiconductor band gap energy and the details of the state at the band edge. It is also well known that ordinary semiconductors (eg, silicon) have different absorption rates for different wavelengths.

  As is apparent from FIGS. 1 and 3, at a given depth in a larger volume of silicon, it functions as a sensor in a VCF sensor group, and a volume of silicon having a given thickness is more sensitive to blue light than green light. It has a large absorptance and a greater absorptance for green light than for red light. However, if the sensor silicon is deep enough in a larger volume, most of the blue and green light will be absorbed by the material on the sensor silicon. Even if light with a substantially flat wavelength intensity spectrum is incident at a larger volume surface, the sensor can actually absorb more red light than green or blue light. Also, the intensity of green light and blue light reaching the sensor is much smaller than the intensity of red light reaching the sensor.

  A typical embodiment of the VCF sensor group of the present invention achieves color separation by capturing photons at different ranges of depth in the volume of semiconductor material. FIG. 2 shows a top layer X01 (made of n-type semiconductor), a second (p-type) layer X09 below the top layer, a third (n-type) layer X02 below the second layer, A vertical (VCF) sensor group including a fourth (p-type) layer X10 below the first layer, a fifth (n-type) layer X03 below the fourth layer, and a p-type semiconductor substrate X11 below the fifth layer. It is a doping profile.

  FIG. 2A is a cross-sectional view (in a vertical plane) of the VCF sensor group. As shown in FIG. 2A, bias and readout circuits are coupled to layers X01, X02, X03, X04, and X05 and to substrate X11.

  Blue, green, and red photodiode sensors are formed by junctions between the n-type and p-type regions of FIG. 2A and are located at different depths below the surface of the semiconductor structure. The red, green, and blue photocharge signals are all taken from the n-type cathodes (X01, X02, and X03) of three separate photodiodes.

The readout circuit of FIG. 2A is non-memory type and is similar to that described in US Patent 09 / 884,863. Each sensor readout circuit is driven from a RESET signal line and is coupled between a photodiode cathode and a reset potential (labeled V _REF in FIG. 2A), a reset transistor (54b for blue light, green light). Including a source follower amplifier transistor (transistors 56b, 56g, and 56r) whose gate is coupled to the photodiode cathode and whose drain is held at potential V _SFD during operation, It further includes column select transistors (transistors 58b, 58g, and 58r) driven from the ROW-SELECT signal line and coupled between the source and column line of the associated source follower amplifier transistor. The subscripts “r”, “g”, and “b” are used to indicate the wavelength band (red, green, or blue) associated with each transistor. As is known to those skilled in the art, the RESET signal works to reset the pixel and does not work during illumination, but after that the column select line works to read the detection signal.

  Each of p-type regions X09, X10 and X11 is held at the ground potential during operation. Each of the n-type regions X01, X02, and X03 is a carrier collection element having a contact portion that leads to (and can be coupled to) a bias circuit and a readout circuit. Before reading each of the sensor groups, the bias circuit resets each n-type region layer with respect to a reset potential (the above-described ground potential). During exposure to the sensed radiation, a reverse-biased pair (electron-hole pair) of adjacent p-type and n-type layers is a photodiode (cathode is layer X01 and anode is layer X09). The photodiode functions as a second photodiode whose cathode is the layer X02 and whose anode is the layers X09 and X10, and whose cathode is the layer X03 and whose anode is the layers X10 and X111). As shown in FIG. 2, each of the n-type layers X01, X02, and X03 is coupled to a bias circuit and a readout circuit, thereby serving as a photodiode terminal (terminal).

  During normal operation, when the photodiode of FIG. 2 is biased reverse, the depletion region is formed to surround most of the silicon in which photons are absorbed. In FIG. 2, the depletion region for the first photodiode (which initially senses blue light) is marked “X04” and the depletion region for the second photodiode (which initially senses green light). Are marked "X05" and "X06", and the depletion region is marked "X07" and "X08" for the third photodiode (which initially senses red light). The part in the depletion region separates the electron-hole pairs formed by photon absorption. This leaves charge on the cathode of each photodiode, and a readout circuit coupled to each cathode converts this charge into an electrical signal. The charge on the cathode of each photodiode is proportional to the number of photons absorbed by the photodiode. This proportionality is the quantum efficiency QE.

  FIG. 3 shows the same curve shown in FIG. 1 (showing absorption of blue, green or red photons by silicon), and the range of carrier collection elements (X01, X02, and X03) and the structure of FIG. Including a line indicating the depletion region. As a result, the region labeled “X01 + X04” in FIG. 3 represents the region of FIG. 2 on the lower surface of the depletion region X04. Further, a region indicated as “X05 + X02 + X06” in FIG. 3 represents the region in FIG. 2 between the upper surface of the depletion region X05 and the lower surface of the depletion region X06. Further, the region indicated as “X07 + X03 + X08” in FIG. 3 represents the region in FIG. 2 between the upper surface of the depletion region X07 and the lower surface of the depletion region X08. FIG. 3 results in three different “sensor” regions, where the three photodiodes in FIG. 2 absorb photons and the charge resulting from such absorption remains (and outside the sensor region where the charge is generated). Does not move) and can be measured by the readout circuit. Electron-hole pairs generated between three sensor regions (for example, electron-hole pairs generated in layer X09 between the bottom surface of depletion region X04 and the top surface of depletion region X05) still diffuse to the sensor region. Can be generated (with high efficiency) and charge can be generated on the photodiode that can be measured by the readout circuit.

  Depending on the wavelength, the selective absorption of photons determines the photosensitivity of the three photodiodes. For 450 nm, 550 nm, and 650 nm light, the depth and range of the sensor region determines the spectral sensitivity when considering the location of the sensor region (“X01 + X04”, “X05 + X02 + X06”, and “X07 + X03 + X08”) associated with the curve in FIG. To do. In the “X01 + X04” region, incident blue light is absorbed much more than incident green and red light, but only a small amount of green and red light is absorbed. In the “X01 + X04” region, incident green light is absorbed much less than incident blue light, and incident green light is absorbed much more than incident red light. In the “X05 + X02 + X06” region, the incident green light is absorbed more than the incident blue light (since most of the incident blue light in the region “X01 + X04” is absorbed in that region and does not reach the region “X05 + X02 + X06”), and the incident green light Light is absorbed more than incident red light (eg, only a small amount of incident red light in region “X01 + X04” is absorbed in that region, so that most such red light reaches region “X05 + X02 + X06”) As well).

  The full range of incident light wavelengths (not just the three wavelengths 450 nm, 550 nm, and 650 nm) determines the spectral sensitivity of the three photodiodes of FIG. 2, which is similar to that shown in FIG. Curve C1 in FIG. 4 is the spectral sensitivity of the top (“blue light”) photodiode similar to the top (“blue light”) photodiode in FIG. 2, and curve C2 in FIG. 4 is the middle of FIG. (“Green light”) is the spectral sensitivity of an intermediate (“green light”) photodiode similar to a photodiode, and curve C3 in FIG. 4 is the bottom (“red light”) photodiode similar to the photodiode ( “Red light”) is the spectral sensitivity of the photodiode.

  At an important stage of the embodiment (including the VCF sensor group of FIG. 2), the VCF sensor group of the present invention uses three photodiodes. Such VCF sensor groups are well suited for use with DSCs or digital video cameras. However, in other embodiments, the VCF sensor group of the present invention uses two (or more than three) photodiodes arranged at different depths, at least in a volume of primarily semiconductor material.

  As already mentioned, materials whose absorptance varies with wavelength change the spectral amount of radiation that propagates through them as a function of depth. Such materials have multiple functions in the VCF sensor group. They can function as filters. It also functions as a sensor (sensor element). For example, in FIG. 2, each of silicon regions X01, X02, X03, X09, X10, and X11 also functions as a filter and as an element of at least one sensor. In other embodiments, other semiconductors (or at least two different semiconducting materials) function as sensors (or sensor elements) and filters as well.

  At some stage of an embodiment, the vertical color filter (“VCF”) sensor group of the present invention includes vertically stacked sensors, the sensor includes a top sensor having a top surface, and any other sensor in the group. Before reaching, the sensed radiation is incident on the top surface and propagates to the top sensor (through the top surface). The top surface defines a standard axis (and is usually at least substantially planar). Preferably, radiation propagating along the vertical axis of the group has an angle of incidence of less than about 30 degrees with respect to the standard axis when incident on the group so that the radiation is incident on the top sensor. This sensor is made.

Referring now to FIGS. 5, 6, and 7, we have semiconductor materials other than silicon (eg, semiconductor materials other than silicon that are not InGaN or other III-V semiconductor materials, or III-V materials). Describes an embodiment used to form a VCF sensor group. One such semiconductor material that is neither silicon nor a III-V material is silicon carbide. FIG. 5 is a simplified cross-sectional view (in the vertical plane) of a group of VCF sensors including a top sensor 10, a bottom sensor 14, and an intermediate sensor 12 between the sensors 10 and 14. Each of sensors 10 and 12 is made of In _x Ga _1-x N semiconductor material, where x = 0.475 for sensor 10 and x = 0.825 for sensor 12. The sensor 14 consists essentially of silicon. Typically, each of sensors 10 and 12 consists of multiple layers of In _x Ga _1-x N semiconductor that determine at least one junction biased in operation to function as a photodiode. The sensor 14 may also be a multi-layer of differently doped silicon (eg, an n-type silicon layer and p-type silicon layers above and below the n-type silicon layer that are biased during operation to function as a photodiode. Of adjacent parts).

  Using a sensor consisting essentially of one or more III-V semiconductor materials, a junction (any kind including a heterojunction and a Schottky barrier) that is biased in operation to function as a photodiode. It is within the scope of the present invention to determine.

FIG. 6 shows the band gap energy (indicated as “energy gap” in the central row) in the electron volt of In _x Ga _1-x N semiconductor with different levels of indium (different values of the subscript “x”). ). FIG. 6 also lists the optical wavelengths corresponding to each band gap energy (in the right column). As a result, FIG. 6 shows. The maximum wavelength that can be absorbed by a sensor made from In _0.1 Ga _0.9 N is 388 nm, and the maximum wavelength that can be absorbed by the sensor 10 of FIG. 5 (made from In _0.475 Ga _0.525 N semiconductor) is about 500 nm. The maximum wavelength that can be absorbed by the sensor 12 of FIG. 5 (made from In _0.825 Ga _0.175 N semiconductor) is about 612 nm.

  As a result, sensor 10 transmits all (or substantially all) green and red light incidents, preferably it transmits all (or substantially all) blue light incidents in FIG. Thick enough to absorb on the swarm. Similarly, sensor 12 transmits all (or substantially all) red light incidents, preferably it absorbs all (or substantially all) green light incidents on the sensor group of FIG. Thick enough to do. The sensor 14 preferably has a thickness sufficient for it to absorb all (or at least a significant amount) of red light incidence.

In general, when using an In _x Ga _1-x N semiconductor semiconductor material (or other group III-V semiconductor material) to form a VCF sensor group, the material parameters (eg, In _x Ga _1-x The parameter “x” in N is to achieve the desired bandgap energy for each sensor in the VCF sensor group (eg, to make certain sensors transparent to light having a wavelength greater than the threshold). Chosen.

  More generally, in some embodiments of the present invention, at least one semiconductor material other than silicon is used to implement at least one sensor of the VCF sensor group. This material is also chosen to selectively sensitize this group of different sensors to different wavelength bands. In some such preferred embodiments, at least two different types of semiconductor materials are used to implement the sensors of the VCF sensor group, which material selects different sensors of this group for different wavelength bands. Chosen to be sensitive.

Some embodiments of the VCF sensor family of the present invention include at least one “avalanche” photodiode, which is a photodiode that collects one or more electrons per absorbed photon as a result of the “avalanche” gain process. is there. In the avalanche gain process, the first electron-hole pair generates at least one additional electron-hole pair, and the electronic energy of the first electron-hole pair is a semiconductor forming a photodiode sensor. Assume that the bandgap energy of the material is exceeded. The semiconductor material has an ionization coefficient (a _n ) for electrons and an ionization coefficient (a _p ) for holes. Wherein 1 / a _n is electrons by impact ionization - before generating hole pairs, the average distance that electrons are accelerated in the material. 1 / _ap is the average distance at which holes are accelerated in the material before generating electron-hole pairs by impact ionization. Or photodiode in the semiconductor material {This is the ratio of ionization coefficients, is a _p / a _n, in the photodiode semiconductor material (which the ratio of ionization coefficients, a _p / a _n is much larger than 1 It is much more difficult to implement a practical avalanche photodiode.

In some embodiments of the present invention, at least one sensor of the VCF sensor group is an avalanche sensor including an optical absorption region and an avalanche region separated from the optical absorption region. For example, FIG. 7 is a cross-sectional view of such an avalanche sensor that can be included in a group of VCF sensors. The sensor of FIG. 7 includes a substrate 20 (made from n ⁺ silicon), a layer 21 on the substrate 20 (made from n ^- silicon), and a layer 22 on the layer 21 (n-type In having a relatively low dopant concentration). It made from _x Ga _1-x N semiconductor material), and includes a layer 23 on layer 22 (made of p-type in _x Ga _1-x N semiconductor material having a relatively high dopant concentration). Metal contact 27 is formed on layer 23, and substrate 20 is coupled to metal contact 25 by a vertical contact region of n ⁺ silicon. During operation, a bias voltage is applied across the metal contacts 25 and 27. A read circuit can also be coupled to the contact 27. Between layers 21, 22, and 23 and insulating material 24 (which can also be silicon nitride) (and between substrate 20 and material 24), layers 21, 22, and 23, and insulating material 24 Surrounding is provided by an insulating material 27A, which can be composed of a photoresist, such as a polymethylglutarimide resist.

In operation, layers 22 and 23 function as optical absorption regions in which electron-hole pairs are formed in response to incident photons. In _x Ga _1-x N semiconductor material forming a layer 22 and 23 is much greater than 1 (or significantly less) has a ratio of ionization coefficients (a _p / a _n). As a result, layers 22 and 23 are not utilized as avalanche gain regions.

In operation, layers 21 and 20 function as avalanche gain regions where electron-hole pairs are formed in response to electron-hole pairs formed in the optical absorption region. Silicon forming the layer 22 and 23 has a ratio very close ionization coefficient 1 than is the ratio of ionization coefficients for layer 22 and _{23 (a p / a n)} .

  In general, some embodiments of the VCF sensor group of the present invention include at least one sensor that is an avalanche photodiode. Here, the avalanche photodiode includes an optical absorption region made of a semiconductor material (eg, InGaN) whose electron ionization coefficient is much different from its hole ionization coefficient, and is substantially equal in terms of electrons and holes. It includes an avalanche region separated from an optical absorption region made from another semiconductor material (eg, silicon) having a coefficient. One important application of sensors used as avalanche photodiodes has been significantly reduced during propagation through at least one filter and / or at least one other sensor before reaching the avalanche photodiode (eg, To detect low intensity radiation, such as radiation with that intensity (by absorption).

  In other embodiments of the VCF sensor group of the present invention, at least one filter that does not function as a sensor (or sensor element) functions as a sensor (or as one element or as one or more sensors), at least Stacked using a single layer of semiconductor material. Such a filter can have the same spectral sensitivity that silicon in the embodiment of FIG. 2 has, but is not necessarily required.

  Filters remove wavelengths from radiation in the following sense: For each filter, there are first and second wavelengths. If the first and second wavelengths are incident on the filter with intensities “I1” and “I2”, respectively, the transmitted intensities of the first and second wavelengths (after being transmitted through the filter) are respectively “O1” and “O2”, where O1 ≦ I1, O2 ≧ I2, and O1 / O2 <I1 / I2.

  One type of filter included in some embodiments of the VCF sensor group of the present invention is a “conversion filter” (eg, “conversion layer”) that changes the wavelength of incident electromagnetic radiation. A “conversion” filter absorbs photons of a certain wavelength and emits photons at at least one short or long wavelength. Usually, the material containing the conversion filter is a nonlinear optical material. Conversion filters can be used to convert photons with frequencies below the cut-off frequency of a sensor to higher frequencies so that they can be detected. Alternatively, a conversion filter can be used to convert photons having frequencies above the threshold frequency to lower frequencies so that they can be detected. An example of the latter is an X-ray conversion layer that is used to convert X-rays (X-rays easily penetrate most detection materials) into visible light that is easily detected. Some embodiments of the present invention are either gadolinium oxysulfide layers having a thickness of about 100 μm or thallium-doped cesium iodide layers having a thickness in the range of about 100 μm to 600 μm. Can be used as such an X-ray conversion layer.

There are two related methods for detecting photons in a group of spectral bands, each of which can be used to implement the present invention. In some embodiments of the VCF sensor group of the present invention, at least one filter moves photons out of at least one wavelength band, and at least two vertically stacked sensors detect remaining photons, where each The sensor is a different element from each filter. Other embodiments of the VCF sensor group of the present invention do not include non-sensor filters (non-sensor filters) but include sensors that are sensitive to a limited wavelength band. For example, by including a first sensor and a second sensor below the first sensor, other embodiments of the invention implement a combination of these approaches. Here, the first sensor absorbs a limited range of wavelengths and passes photons outside this range to the second sensor, and the second sensor is sensitive to all wavelengths. In this embodiment, the first sensor functions as a filter for the second sensor.

  In some embodiments of the present invention, the at least one non-sensor filter is between at least one set of vertically stacked sensors of the VCF sensor group, or on top of the group of top sensors, or the bottom sensor of the group. Placed below. When such a filter is placed between a set of vertically stacked sensors in a VCF sensor group, the filter can be any of a variety of different types, including (but not limited to): This filter can absorb radiation in one wavelength band and transmit other wavelengths without reflecting any radiation of any wavelength. This filter can reflect radiation in one wavelength band and transmit other wavelengths without absorbing any radiation of any wavelength. Alternatively, the filter is highly transmissive for radiation in one wavelength band, is absorbing for radiation in another wavelength band, and is reflective for radiation in the third wavelength band. The VCF sensor group of FIG. 8 includes two non-sensor filters of the latter type. That is, the color filter 43 and the color filter 48. It should be understood that the sensors in FIG. 8 are only one example of many possible embodiments of the invention.

  FIG. 8 is a cross-sectional view (in the vertical plane) of a portion of one embodiment of an array of VCF sensor groups of the present invention, with two non-sensor filters (layers 43 and 48) and four separation layers (gap barrier 42). , 44, 47, and 48). Each separation layer can be composed of silicon dioxide. In FIG. 8, one VCF sensor group includes a layer 51 (made from an n-type semiconductor) and a layer of p-type semiconductor material 50 above and below the layer 51, below the material 50 and below the insulating layer 49 and layer 49. A color filter 48, an insulating layer 47 below the filter 48, a layer 46 (made of n-type semiconductor) and a layer of p-type semiconductor material 45 above and below the layer 46, and an insulating layer 44 and layer 44 below the material 45. Underneath the color filter 43, an insulating layer 42 under the filter 43, a layer 41 (made of n-type semiconductor) and a p-type semiconductor substrate material 40 above and below the layer 41 are included. A vertical plug contact connects each of the layers 41, 46, and 51 to the top surface of the sensor group. As a result, each of layers 41, 46, and 51 can be coupled to a bias and readout circuit. In order to prevent radiation (normally incident on the top surface of the sensor group) from reaching the plug contact (which reduces frequency selectivity), a light shield 54 is mounted on the plug contact. The array of FIG. 8 also includes a second group of VCF sensors. The second group of VCF sensors comprises a layer 63 (made from an n-type semiconductor) and a layer of p-type semiconductor material 50 above and below layer 63, an insulating layer 49 below material 50, a color filter 48 below layer 49, Insulating layer 47 under filter 48, layer 62 (made of n-type semiconductor) and layers of p-type semiconductor material 45 above and below layer 62, insulating layer 44 under material 45, collar under layer 44 The filter 43, the insulating layer 42 under the filter 43, the layer 61 (made of n-type semiconductor), and the p-type semiconductor substrate material 40 above and below the layer 61 are included. Vertical plug contacts connect each of layers 61, 62, and 63 to the top surface of the sensor group. As a result, each of layers 61, 62, and 63 can be coupled to a bias and readout circuit. In order to prevent radiation (normally incident on the top surface of the sensor group) from reaching the plug contact, a light shield 54 is mounted on the plug contact of the second VCF sensor group.

In the variation of the embodiment of FIG. 8, horizontal variations in n-type layers 51 and 63 (which lack vertical contact portions) are exposed at the top surface of the sensor group (and depending on the semiconductor material 50). Not covered). Each such exposed n-type layer can be directly coupled to the bias and readout circuitry (eg, by the metal formed thereon). Similarly, in a variation of the embodiment of FIG. 8, n-type layers 46 and 62 exist directly under layer 47 (and are not separated from layer 47 by p-type semiconductor material 45), and n-type layer 41 And 61 are directly under layer 42 (and are not separated from layer 42 by p-type semiconductor material 40).

  Each of the p-type semiconductor layers in FIG. 8 is held at the ground potential during operation. Each of the n-type semiconductor layers is coupled by a plug contact that can (and can be coupled) to a bias and readout circuit. Prior to each readout of each sensor group, the base circuit resets each of the n-type layers to a reference potential (upper ground potential). During exposure to the sensed radiation, the reverse biased set of adjacent p-type and n-type layers of the first sensor group functions as a photodiode. The cathode is layer 51 and the anode is in the proximity layer of material 50 (referred to as a “blue” sensor because it absorbs more blue photons than green or red photons in response to the incidence of white light at the top of the sensor group). A first photodiode. The cathode is layer 46 and the anode is a close layer of material 45 (referred to as a “green” sensor because white light absorbs more green photons than blue or red photons when incident on the top of the sensor group). A second photodiode. The cathode is layer 41 and the anode is a proximity layer of material 40 (referred to as a “red” sensor because white light absorbs more red than blue or green photons when incident on the top of the sensor group). Third photodiode. During exposure to the sensed radiation, the reverse biased set of adjacent p-type and n-type layers of the second sensor group also functions as a photodiode. The cathode is layer 63 and the anode is material 50 (referred to as a “blue” sensor because it absorbs more blue photons than green or red photons in response to the incidence of white light at the top of the second sensor group) A first photodiode which is a proximity layer of The cathode is layer 62 and the anode is of material 45 (referred to as a “green” sensor because white light absorbs more green photons than blue or red photons when incident on the top of the second sensor group). A second photodiode which is a proximity layer. The proximity of the cathode is layer 61 and the anode is material 40 (referred to as a “red” sensor because white light absorbs more red than blue or green photons when incident on the top of the second sensor group) A third photodiode that is a layer.

  When layers 40, 41, 45, 46, 50, and 51 are made from crystalline silicon (as usual), layers 51 and 50 are preferably thinner than layers 46 and 45, respectively, and layers 41 and 40 Are thinner than layers 51 and 50, respectively. This ensures that significantly more red light than green light is incident on each red sensor, and that much more blue light than green light is absorbed by each blue sensor, while each green sensor The intensity ratio of green light to red light incident on the sensor is by an amount sufficient to ensure that it is sufficiently high. Typically, the combined thickness of layers 51 and 50 in the first sensor group (and layers 63 and 50 in the second sensor group) is about 0.3 μm or less, or layers 45 and 46 (and in the first sensor group) The combined thickness of layers 45 and 62) in the second sensor group is approximately 5 μm.

  The color filter 43 is a “red pass / cyan reflection” filter that is highly transmissive to red light but reflects most or nearly all blue and green light incident thereon. The color filter 48 is a “yellow / blue reflection” filter that is highly transmissive to red and green light incident thereon, but reflects most or nearly all blue light incident thereon. Other embodiments of the invention use transmissive filters that are not reflective.

  Filter 43 functions to increase the ratio of red light to green light (and the ratio of red light to blue light) absorbed by each red sensor, and if filter 43 is removed, Red / green discrimination problems that can affect the red sensor can be reduced or eliminated. Similarly, the filter 48 functions to increase the ratio of green light to blue light absorbed by each green sensor, and if the filter 48 is removed, the green sensor may be affected. Certain green / blue identification problems can be reduced or eliminated.

  Since the blue light reflected from the filter 48 has another opportunity to be absorbed by the blue sensor, the filter 48 also increases the ratio of blue light to green (and red) light absorbed by each blue sensor. To function. Since there is only a slight reflection from the filter 48 to the blue sensor of red and green light, the absorption of each blue sensor of blue light is improved without increasing the response to red and green light. Similarly, since the green light reflected from the filter 43 has another opportunity to be absorbed by the green sensor, the filter 43 also increases the ratio of green light to red light absorbed by each green sensor. To function. Since there is only a slight reflection of the red light from the filter 43 to the green sensor, the green light absorption of each green sensor is improved without increasing the response to the red light. Almost all blue light is absorbed by the blue sensor or reflected by the filter 48 towards the blue sensor, so blue light is unlikely to reach the green sensor.

  There are many types of materials that act as filters in a group of VCF sensors (eg, filter 43 or 48 in FIG. 8, a filter that is reflective in the wavelength band and transmissive at all other wavelengths, or is absorbing in the wavelength band). Filter but not reflective). These materials can also be used in combination or in various thicknesses. This arrangement is determined in part by their optical properties, but is optimized by process integration.

  The material and the interface between the materials can reflect photons. When the reflectivity of the mirror is selective by wavelength, the mirror (material and interface between materials) can function as a filter in the VCF sensor group of the present invention. For example, some embodiments of the VCF sensor group of the present invention include dichroic mirrors, both of which transmit radiation in a first wavelength band and reflect radiation in a second wavelength band.

  As mentioned above, a stack of materials whose optical absorption varies with wavelength can be used as a filter in various embodiments of the VCF sensor group of the present invention. In a preferred embodiment including a layer of variously doped semiconductor materials (eg, silicon), at least one semiconductor layer is used as both a filter and a sensor. In VCF sensor groups where the layer of semiconductor material is used both as a filter and as the cathode (or anode) of a photodiode sensor, the spectral sensitivity of the sensor is the bias voltage applied across the anode and cathode of the photodiode. It can be controlled somewhat by controlling, or it can be controlled by determining the doping level and the structure spacing of the dopant atoms and sensor elements.

  Another type of filter included in some embodiments of the invention is a thin metal film. A thin metal film can act as a partial reflector, thus filtering incident photons. The reflected photons return through any layer above them, giving them a second chance to be absorbed.

  Other types of filters included in some embodiments of the present invention include interference filters that reflect one wavelength and pass other wavelengths (eg, a stack of dielectric materials having different dielectric constants), and organic And inorganic dyes and pigments.

  In some embodiments of the invention, the filter is distributed between any array of VCF sensor groups in various patterns, eg, as described in application 10 / 103,304. The filters can all be the same, but are not necessarily the same. Preferably, each filter is integrally formed using one of the VCF sensor groups (eg, as a layer formed on or between the semiconductor layers). Alternatively, the filter can be manufactured separately from the sensor group and then placed on the sensor group array and bonded to the VCF sensor group (otherwise attached or held in a fixed position) can do. This filter can be provided in an alternating or “check board” fashion, as shown in FIG. 8A, where each square marked “RGB” represents a group of VCF sensors, and “X” Each square marked represents a group of VCF sensors including one of the filters. As shown in FIG. 8A, each odd-numbered sensor group in each odd-numbered column includes one of the filters, and each even-numbered sensor group in each even-numbered column includes one of the filters. As a result, an optimum spatial frequency is obtained between the color sensor group having a filter and the color sensor group having no filter.

  Alternatively, the filter can provide the pattern shown in FIG. 8B, where each square marked “RGB” represents a group of VCF sensors and each square marked “X” is one of the filters. The VCF sensor group containing is shown. When the filter is provided in the FIG. 8B pattern, it guarantees that both types of image readout include any combination of color sensor group output and color filter, while the filter is fully measured color readout and mosaic. • Distributed in a manner that allows both emulation readouts. Alternatively, the filters can be distributed between the sensor groups of the VCF sensor group array in many other patterns. Some of them are described in application 10 / 103,304.

  Some embodiments of the VCF sensor group of the present invention include at least one lens instead of or in addition to at least one filter. For example, microlenses can be formed on all or some of each of the VCF sensor groups of the VCF sensor group array. When metallization (or another structure) limits the size of the apertures in the VCF sensor group (the area in the image plane where incident radiation propagates to at least one sensor), photoresist can be volumed over the apertures, and Thereafter, upon exposure, the photoresist material melts into convex or concave features, thereby forming microlenses. Depending on the properties of the material, including the lens and lens shape, the lens functions as a filter as well as the lens itself. For example, FIG. 9 is a cross-sectional view (in the vertical plane) of a variation portion of the VCF sensor group array of FIG. The array of FIG. 9 includes a first VCF sensor group that includes n-type semiconductor layers 51, 46, and 41 formed in a p-type semiconductor material, with layers 41, 46, and 51 on top of the sensor group. It includes a light shield 54 mounted on each contacted vertical contact and a contact that prevents radiation (which normally enters the top surface of the sensor group from reaching the contact). The array of FIG. 9 also includes a second group of VCF sensors including n-type semiconductor layers 61, 62, and 63 formed in a p-type semiconductor material. Light shields 53 and 54 are formed in a layer 64 that is transparent to the radiation being sensed. Light shields 53 and 54 surround the opening of the first sensor group, and light shield 53 and another light shield (not shown) surround the opening of the second sensor group. Convex microlenses 65 are formed on layer 64 on the first group of openings, and convex microlenses 66 are formed on layer 64 on the second group of openings.

  When microlenses are distributed between the sensor groups of a VCF sensor group array in an alternating pattern (eg, that shown in FIG. 8A), a small group of sensor groups with different sensitivities to radiation can be independently selected. . This provides an extended dynamic range of the array as a whole.

  The aperture of each sensor group in the VCF sensor group array is typically square or octagonal, but instead has another shape (eg, rectangular, circular, or irregular shape). The microlenses formed over the apertures of all or some of the sensors in such an array are usually square, but can have other shapes.

  Some embodiments of the VCF sensor group of the present invention include at least one microlens that is a compound lens (eg, a combination of convex and concave microlenses).

  It is well known to form a microlens as the top layer of a CCD image sensor array with one microlens on each sensor of the array. For example, a microlens as an intermediate layer of a CCD image sensor array, with two vertically separated microlenses on each sensor of the array, and a color filter between each such set of vertically separated microlenses. It is also well known to include In an embodiment of the invention, in order to refract radiation to the top sensor of this group (eg, a sensor including layer 51 in FIG. 9), a microlens (eg, microlens in FIG. 9) is a member of the VCF sensor group. Placed against the sensor. As a result, at least some radiation propagates through the top sensor to each of the sensors located below the top sensor, and this radiation is absorbed by this group before it can reach the bottom sensor. It contains at least one wavelength that is neither reflected nor reflected by this group of elements.

  Materials used in semiconductor processes (for other purposes) are highly desirable to equip filters, lenses, and sensors in normal embodiments of the present invention. This is because they can be added to the VCF sensor group without modifying the process. Examples of such materials are polysilicon, silicon dioxide, and silicon nitride. The polysilicon layer can be used as a filter. The absorption spectrum of this filter depends on its crystal properties, conductivity, layer thickness and depth relative to other elements of the VCF sensor group. A layer of silicon dioxide and silicon nitride formed on the surface (eg, silicon surface) can form an interference filter in the VCF sensor group.

  The expression “minimum size” carrier collection element of the VCF sensor group embodying the present invention is used to denote each carrier collection element of this group. On a plane perpendicular to the standard axis defined by the top surface of the top sensor of this group, this projection is larger than the projected area of each other carrier collection element of this group on such surface. With no territory. The expression “minimum collection area” (of this group) is projected onto the plane perpendicular to the standard axis defined by the top surface of the top sensor of this group, of the smallest sized carrier collection element of this group. Used to indicate a region.

  In embodiments of the sensor group of the present invention, as in the sensor group of FIGS. 10, 10A and 10B, the carrier collection element of one sensor of this group is more than having the smallest size carrier collection element of each of this group. , Having a substantially larger “size” (region projected on a plane perpendicular to the standard axis of the top surface of the top sensor of this group). In a preferred embodiment of this type, one carrier collection element of the sensor group has a size that is at least twice the minimum collection area of the group. This carrier collection element is typically shared by at least one other sensor group in the array, and its size is usually at least substantially equal to the sum of the sizes of all groups sharing it.

  The array of FIG. 10 includes a plurality of sensor groups, six of which are shown in FIG. Each sensor group includes one green sensor (its carrier collection area is not shared with any other sensor group), one blue sensor (shared with one other sensor group), and one Includes a red sensor (shared with one other sensor group). The carrier collection area of each red sensor and each blue sensor is larger than the collection area of green photons.

  In the variation of the array of FIG. 10 or 10B, at least one carrier collection region is first formed to be laterally separated from each other, and then together to form a single effective carrier collection region. Contains two or more parts shared. For example, each blue sensor can include two laterally separated carrier collection regions for blue photons, each formed on a different carrier collection region for green photons, and two carrier collection regions for blue photons. Are laterally separated to provide space for forming at least one transistor on the top surface of the array therebetween. The two laterally separated carrier collection areas of each blue sensor represent a single carrier collection area for blue photons (this area has a larger overall size for each of the array's carrier collection areas for green photons). Shorted together to form.

Referring again to FIG. 10, the charge collected on each red sensor is converted into an electrical signal that represents twice the average of the red light intensity incident on the two sensor groups sharing the red sensor. The charge collected on each blue sensor is converted into an electrical signal that represents twice the average of the blue light intensity incident on the two sensor groups sharing the blue sensor. As a result, the resolution of the array for green light is twice that for red or blue light. This type of array increases the signal relative to the noise ratio in the blue and red channels while maintaining high spatial resolution in the green (or luminescence) channel. This high luminescence resolution is achieved in contrast to a conventional image sensor array using a Bayer pattern with a green sensor in only half of the pixel locations. This is because every pixel position has an active green sensor. Those skilled in the art will maintain high luminescence resolution through a high sampling rate in the green channel to reduce the presence of artificial aliasing in the interpolated image generated using such an array. Larger blue and red carrier collection areas further reduce the presence of artificial aliasing.

  In other embodiments, the blue sensor carrier collection area of the array of VCF sensors is smaller than the red and green sensor carrier collection area of the array.

  In some embodiments of an array of VCF sensor groups, one sensor group includes at least one sensor (or sensor element) shared with another sensor group. FIG. 10A is a cross-sectional view (in the vertical plane) of such an array. In FIG. 10A, the first group of sensors includes a layer 102 (made from an n-type semiconductor) and a first sensor that in turn includes a region 100 of p-type material directly above and below layer 102, and layer 101 ( and a second sensor comprising in turn a region 100 of p-type material directly above and below the layer 101. FIG. 10A also shows a second sensor group including a third sensor (which in turn includes a layer 103 made of n-type semiconductor and a region 100 of p-type material directly above and below layer 103) and a second sensor. Indicates. As a result, the second sensor (which includes layer 101) is shared by the two sensor groups, and each of the separated first and second sensors is placed at the same vertical level in the array.

  In the array of FIG. 10A, the output of the first sensor indicates the blue component of the first pixel, the output of the third sensor indicates the blue component of the second pixel, and the output of the second sensor is the first pixel. The green component of both the pixel and the second pixel is shown. The array of FIG. 10A is another way of having a better resolution for green light than for blue light (eg, by using separate first, second, and third sensors), and for blue light and In another way with better resolution for green light (eg by averaging the output of the first and third sensors and using this averaged value with the output of the second sensor), It can operate suitably. The array of FIG. 10A is a simple embodiment with sensors at only two depths. Other embodiments of the array of the present invention have vertically aligned sensors at three or more depths.

  In the VCF sensor group array of FIG. 10B, the red and blue sensor carrier collection elements of each sensor group have a larger size than the green sensor carrier collection elements of this group. The array of FIG. 10B includes a plurality of sensor groups, four shown in FIG. 10B. Each sensor group includes one green sensor whose carrier collection area (182, 183, 184, or 185) is not shared with any other sensor group, and the carrier collection area (180) is each of the three other sensor groups. The carrier collection region (181) includes one red sensor shared with each of the three other sensor groups. The blue and red photon carrier collection region is larger than the green photon carrier collection region. The charge collected on each red sensor (due to photon absorption) is converted into an electrical signal (usually a voltage) indicating the average of the red light intensity incident on the four sensor groups sharing the red sensor. . The electric charge collected on each blue sensor is converted into an electrical signal (usually a voltage) indicating the average of the blue light intensity incident on the four sensor groups sharing the blue sensor. Typically, the voltage output of the red and blue sensors of the FIG. 10B array (and variations on such arrays) need not be scaled with respect to the voltage output of the green sensor. The increase in charge collected on each sensor due to an increase in the carrier collection area of the sensor is proportional to the increase in sensor capacity due to such an increase in the carrier collection area.

  As the output of each sensor group determines the pixel, when fabricating an array of VCF sensor groups, it is necessary to separate the sensor groups from each other to avoid crosstalk between the pixels. If the electrons and holes generated in one sensor group can drift to the other, the resolution of the imager is reduced. In a preferred embodiment of the present invention, such separation is achieved by creating a group of sensors whose physical design includes the charge generated within them.

  Exactly, the “first” and “third” sensors are separated from each other by the np substrate junction, for example, again with respect to FIG. 10A, the large “second” below in the array of FIG. 10A. The “two sensors” (including layer 101) are separated from their neighbors (partially shown but without labeling) at the same vertical level by np substrate bonding.

  Some conventional sensor arrays do not provide such separation between sensors that determine pixels with different outputs. For example, one type of conventional sensor array includes all pixels as described in FIG. 11 and Bartek “Sensors and Actuators A, 41-42 (1994), pp. 123-128”. A photodiode sensor (eg, photodiode 30) made in a common epitaxial silicon (epi) layer (31). In this configuration, the charge generated in one sensor can drift to the next sensor or somewhere far away. Since the structure of FIG. 11 has no isolation region (eg, p-type semiconductor region) between the sensors, the common epilayer (layer 31) can conduct carriers from under one pixel to another. Provide a path.

  Various methods can be used to separate the sensors in the VCF sensor group from each other, or separate the sensor groups (pixels) from each other in the VCF sensor group embodying the present invention. Can be used for Process integration is an important factor in determining the method used. One method that can be used is junction isolation, which is commonly used to isolate transistors in a silicon biasing process. This junction must be able to withstand sufficient voltage across it to prevent leakage. There may be a sufficient amount of doping in the substrate or in the epi layer to provide adequate junction isolation. Alternatively, increasing the doping amount between adjacent regions to be separated from each other may be required to perform junction isolation. This increase in doping can be produced using a “field ion implantation” technique used to isolate adjacent transistors in a MOS process.

  Other embodiments of the VCF sensor group and array of VCF sensor groups of the present invention employs isolation that places an insulating material between the semiconductor regions. This can be done by making each sensor group in a block of semiconductor material with an oxide layer under the sensor group. There are various ways to make such a structure. For example, growing silicon on sapphire, ion-implanting a layer of oxygen through the top layer of a silicon wafer, reacting silicon and oxygen to form an oxide layer, and processing silicon from the wafer Removing a layer and moving it to an insulating substrate.

  Insulation isolation can be used to isolate semiconductor sensor groups from each other in an array of VCF sensor groups. When the sensor groups are arranged laterally from each other and formed in the semiconductor material volume, they form this group on top of the insulating layer, etch the trench in the semiconductor material volume, and also insulate in the trench Such separation can be achieved by growing or laminating the body. More generally, at least one insulator and a doped and biased (in operation) semiconductor material filled and / or lined (covered) trench may be used to provide field isolation (e.g., Trenches lined with more doped semiconductor material than bulk semiconductor material between adjacent structures separated from each other to prevent leakage, and then filled with oxide or other insulating material) In this embodiment, it is used to separate the VCF sensor group of the present invention from each other. The use of such trenches (to isolate conventional CMOS structures) is called “trench isolation” in CMOS technology. Trench isolation can be applied to isolate VCF sensor groups from each other in the normal embodiment of the present invention. Because trenches can be etched deep enough to separate VCF sensor groups at a depth of a few microns, such as trenches made in a typical array of silicon biased VCF sensor groups. This is possible.

An example of a combination of isolation isolation (performed by trench isolation) and junction isolation is shown in FIG. In FIG. 12, a first group of VCF sensors includes vertically separated n-type semiconductor layers 151, 152, and 153 formed in a p-type semiconductor material 150 (which can also be silicon). (For example, silicon). Contact 154 is provided to couple the p-type material to the bias circuit.

  Vertical plug contacts connect each of layers 151 and 152 to the top surface of the sensor group. As a result, each layer can be coupled to a bias and readout circuit. The plug contacts can be formed as described in the above-cited US application 09 / 884,863. The second VCF sensor group includes vertically separated n-type semiconductor layers 161 and 162 formed in p-type semiconductor material 150. The sensors of the first sensor group are separated from each other by np substrate bonding. The lateral isolation between the first and second sensor groups was formed between them by trench isolation, i.e. lined with insulating material 158 (e.g. this could be silicon dioxide or silicon nitride). This is achieved by the trench 157. A trench 155 (backed with oxide 156) separates the first sensor group from a third sensor group (not shown in FIG. 12) adjacent to the first sensor group. An insulating layer 148 under the bottom sensor of each VCF sensor group (which can be silicon dioxide or silicon nitride) also serves to separate the sensor groups from each other.

  The trench used in accordance with the present invention for trench isolation between VCF sensor groups is a shallow trench with a low aspect ratio (eg, 1/4 micron depth of the type conventionally used in some CMOS integrated circuits). A trench). However, typically the trenches used in accordance with the present invention for trench isolation between VCF sensor groups are deep trenches with a high aspect ratio (eg, the type of trench conventionally used in some DRAM integrated circuits). .

  With reference to FIGS. 20-25, we next describe an improved technique for providing buried layer isolation used in preferred embodiments of the VCF sensor group of the present invention. During the operation of each such embodiment of the VCF sensor group of the present invention, a first type (p-type or n-type) is provided between each of the two “carrier collection” sensor regions (of opposite semiconductor types). There is a “non-collecting” volume (part) of the semiconductor material. Carriers (electrons or holes) can be photoexcited in the non-collecting volume of the sensor group. Carriers that have been photoexcited in the carrier collection region or moved to the carrier collection region after photoexcitation elsewhere can be collected by the readout circuit. In some cases, photoexcited carriers in the non-collecting volume of the sensor group can move to the carrier collecting sensor region of the adjacent sensor group. Typically, photoexcited carriers can move from the non-collecting volume to either of at least two carrier collecting sensor regions (in one sensor group or in a different sensor group). Barriers (eg, barrier 205 of FIG. 20 described below) can be formed by the present invention to prevent such movement in undesirable directions.

  As shown in FIG. 20, the sensor group comprises an upper carrier collection sensor region, a lower carrier collection sensor region (including a photodiode cathode 200 comprising n-type semiconductor material), and a photodiode cathode comprising an n-type semiconductor material. 202), non-collecting photodiode anode layers 201 and 203 (including grounded p-type semiconductor material) between sensor regions 200 and 202, and non-collecting photodiode anode layers 204 under sensor region 202 (Including grounded p-type semiconductor material).

  In order to provide isolation between each set of vertically separated sensors of the sensor group, a blanket barrier layer of a first type of more heavily doped semiconductor material is formed on the upper and lower portions of each non-collecting portion. (And thus between the sensors). Here, in the broad sense, we do not imply that any particular method (eg, physical bonding of isolation structures, or ion implantation processes) is used to form the blanket barrier layer. Use “lamination”. For example, as shown in FIG. 20, the sensor group includes a blanket barrier layer 205 (between the p-type material layers 201 and 203 (and thus between the carrier collection sensor regions including the cathodes 200 and 202)). p-type semiconductor material). The upper carrier collection sensor area (including cathode 200) can be a “blue” sensor, the lower carrier collection sensor area (including cathode 202) can be a “green” sensor, And this group can also include a “red” sensor (not shown) under layer 204 and a second blanket barrier layer of p-type material between layer 204 and the red sensor.

  FIG. 21 is a graph showing the dopant concentration as a function of the depth of the sensor group of FIG. 20, where the positions of the cathode layers 200 and 202 and the barrier 205 are shown. During operation of the sensor group of FIG. 20, the presence of the barrier 205 creates an electron potential with a gradient that guides the photoexcited electrons to the nearest layer of the cathode layers 200 and 202, so that the photoexcited electrons are in an undesirable direction. Does not drift (eg, from a point close to the cathode layer 200 to the cathode 202 or to the cathodes of adjacent sensor groups). Because of its location, the barrier 205 also reduces the capacity of the sensor of FIG. 20 below the capacity of the sensor group of FIG. 22 described below.

  The location of the blanket barrier layer according to the present invention (as in FIG. 20) between the vertically stacked carrier collection sensor regions is described in US application 09 / 884,863, cited above, as shown in FIG. Contrast with the position of the blanket barrier at the same vertical level (or slightly below) as each carrier collection sensor area. Application 09 / 884,863 teaches: Each blanket barrier (eg, each of the layers 206 and 207 of p-type semiconductor material shown in FIG. 22) is ion implanted into the entire wafer (to which an array of VCF sensors is to be formed) and carrier The collection sensor region (eg, the region containing the n-type semiconductor material cathodes 200 and 202 shown in FIG. 22) is then on a selected region of each blanket barrier to create sensors for different sensor groups in the array. Formed by ion implantation. Each blanket barrier made in accordance with the prior art (disclosed in application 09 / 884,863) and the present invention is perpendicular to the carrier collection sensor region (closest carrier collection sensor region) of the same sensor group, An object is to prevent carriers generated in the non-collecting part from leaking horizontally to the non-collecting part of the sensor group and then vertically to the carrier collecting sensor region of the other sensor group. An example of a “non-collecting portion” is the portion of the anode layer 201 (including p-type semiconductor material) of FIG. 22 in the middle between the cathodes 200 and 202, very close to the barrier 205 but relatively far from the cathode 200. A portion of the anode layer 201 in FIG. 20 and a portion of the anode layer 203 in FIG. 20 that is very close to the barrier 205 but relatively far from the cathode 202.

  FIG. 23 is a graph of dopant concentration as a function of the depth of the sensor group of FIG. 22, which shows the location of cathode layers 200 and 202 and barriers 206 and 207. FIG. FIG. 22 During operation of the sensor group, the presence of barriers 206 and 207 causes the photoexcited electrons in layer 201 to travel in undesired directions (eg, from close to the cathode layer 200 to the cathode 202 or to the cathode of the proximity sensor group. A potential with a slope that drifts to Depending on their location, barriers 206 and 207 also increase the capacity of the sensor of FIG. 22 above the capacity of the sensor of FIG. 20 described above. The technique of the present invention for placing and forming a blanket carrier has several advantages. It reduces the photodiode capacitance (and consequently increases the output voltage of each photodiode and reduces the time required to reset each photodiode during exposure) and false carrier collection of the sensors Reduces the leakage of carriers photoexcited to the region or to proximity sensors (beyond levels achievable by the prior art). During operation, the potential gradient created by the present invention between vertically separated carrier collection regions (in a group of sensors) is more erroneous in this group than the potential gradient created using the prior art. Provided is a high potential barrier that better prevents leakage of photoexcited carriers to a region (or to proximity sensor groups).

  In addition to a blanket barrier layer of the type discussed with respect to FIG. 20, some embodiments of the present invention include an additional p-type barrier region formed between the carrier collection sensor regions. For example, as shown in FIG. 24, additional barrier regions 207 (including p-type semiconductor material) are at the same depth of the proximity sensor group (eg, cathodes to the left and right of cathode 200), cathode 200 and It can be formed in a p-type semiconductor material between cathode groups (not shown). FIG. 24 is also formed in the p-type semiconductor material between the cathode 200 and the cathode group (not shown) at the same depth in the proximity sensor group (eg, the cathode to the left and right of the cathode 200), An additional barrier region 208 (including p-type semiconductor material) is shown. Additional barrier regions 207 and 208 arranged laterally change the potential gradient between the carrier collection sensor regions of the proximity sensor group. Photoexcited carriers (electrons in the illustrated embodiment) generated at a location close to the first cathode (eg, cathode 200) are directed farther away from the first cathode (eg, in FIG. Although not shown, it drifts (to the cathode of another sensor group located on the right side of the cathode 200).

Additional barrier 207 (and 208) is preferably formed using a self-aligned auxiliary ion implantation process, such as the process described in connection with FIGS. Alternatively, they can be masked separately. As shown in FIG. 25A, the SiO ₂ film 209 is formed on the layer 201. A Si ₃ N ₄ mask is stacked on the SiO 2 film, this mask is etched from the region where the cathode 200 is to be formed, and then n under the exposed portion of the film 209 by ion implantation. A mold cathode 200 is made. As shown in FIG. 25C, the Si ₃ N ₄ mask is then removed and another ion implantation is performed to create a p-type barrier 207. Finally, as shown in FIG. 25D, further SiO ₂ is grown on the exposed SiO ₂ surface of the entire structure, minimizing the step between portions of the exposed SiO ₂ surface.

During the manufacture of the VCF sensor group, various methods can be used to stack a semiconductor material or an insulating material on top of other semiconductor materials. One method is to physically move material from one wafer to another and bond the material to the final wafer. This leaves an island of sensor material on the substrate. These can be insulated by an insulating protective film, which is yet another insulating separation. Bonded wafers can be fabricated with leak and yield characteristics as good as those of bulk wafers, and this fabrication process in particular creates a thermally Si / SiO ₂ interface in the bonded wafer.

  14A-14L, we next describe how some of the fabrication techniques described above can be used to fabricate one of the VCF sensor groups of FIG. 8 in a suitable manner. With suitable manufacturing methods, the color filters 43 and 48 can be inexpensively included in the array of VCF sensors. The fabrication techniques described with respect to FIGS. 14A-14L (and variations thereof) are similar to the fabrication of several types of semiconductor integrated circuits (eg, circuits including transistors), as well as other VCF sensor groups of the present invention. Embodiments and arrays thereof can be used.

FIG. 14A shows the result of performing the first step of the process sequence. This is a step of ion-implanting the n-type layer 41 into the p-type substrate 40 and then growing a SiO ₂ layer on the substrate 40 by a thermal oxide film growth process. Alternatively, layer 42 (and layers 44, 47, and 49) can be made from another insulating material, such as silicon nitride (SiN).

FIG. 14B shows the result of performing the next step in the process sequence. This is the step of depositing a “red transmission / cyan reflection” filter 43 on the layer 42. The filter 43 can alternatively be an interference filter made from the layers SiN and SiO ₂ . Alternatively, the filter 43 is an interference filter comprising layers of materials with different refractive indices (other than layers of SiN and SiO ₂ ), preferably a material from a lamination process that can be performed using conventional CVD equipment. It is also possible. Filter 43 is alternatively a “red transmission / cyan reflection” filter that absorbs green and blue radiation but does not reflect much.

FIG. 14C shows the next step in this process sequence. This is a step of bringing the second wafer into contact with the wafer of FIG. 14B. In particular, the second wafer includes a substrate 45 (of p-type silicon) and a SiO ₂ layer 44 (grown on the substrate 45). After this, as shown in FIG. 14D, the second wafer layer 44 is bonded to the first wafer filter 43, which is sandwiched between the SiO ₂ layers 42 and 44. More generally, the bonding of two wafers (some layers of the inventive VCF sensor group are formed thereon) can be used during the manufacture of the present invention. Any of a variety of well-known bonding techniques can be used to produce the usual embodiments of the present invention. For example, it is described in “Pasquariello et al.,“ Low-temperature wafer bonding of InP / Si by plasma assist ”in the IEEE Journal Volume 8 on January 1, February, 2002, issue 1 on selected topics of quantum electronics.

  FIG. 14E shows the result of performing the next step in the process sequence. This is a step of reducing the thickness of the p-type substrate 45 to a desired thickness when it is necessary to reduce the thickness. This may be done by polishing (polishing) the exposed surface of the substrate 45 to a thickness of about 0.5 μm, cutting, or some other means.

14F and 14G show the results of performing the next step in the process sequence. This involves ion-implanting n-type layer 46 into substrate 45 and then growing a SiO ₂ layer 47 on the exposed (top) surface of substrate 45 by a thermal oxidation growth process (shown in FIG. 14F), and Thereafter, as shown in FIG. 14G, a filter layer 48 (which can be composed of SiN material, but is not essential) is laminated on the SiO ₂ layer 47. FIG. 14H shows the next step in the process sequence. This is the step of contacting the third wafer with the bonded and processed wafer of FIG. 14G. Thereafter, as shown in FIG. 14I, layer 49 of the third wafer is bonded (preferably by a thermal bonding process) to the exposed (top) surface of layer 48, and layer 48 is composed of SiO ₂ layer 47 and Sandwiched between 49.

Both layers 47, 48, and 49 (as shown in FIG. 14) include interference filters that function as “yellow light transmission / blue light reflection” filters. Alternatively, prior to bonding a third wafer (of the type shown in FIG. 14H), an interference filter comprising three or more alternating layers SiN and SiO ₂ is formed on the structure of FIG. 14G with SiN and SiO _2. It can be formed by laminating additional layers. In another alternative embodiment, a third wafer (which is of the type shown in FIG. 14H but preferably has a material layer other than SiO ₂ instead of the SiO ₂ layer 49 of FIG. 14H) is bonded to the top surface of the stack. before, it is possible to form an interference filter comprising a stack of material layers having different refractive indices (a stack) (stack are not composed of layers of SiN and SiO ₂₎ over the structure of Figure 14E. Filters 47, 48 and 49 are alternatively "yellow light transmission / blue light absorption" filters that absorb blue light but do not reflect much blue light. The third wafer includes a substrate 50 (of p-type silicon) and a SiO ₂ layer 49 (grown on the substrate 50), as shown in FIG. 14H. Any of a variety of known coupling techniques may be used to achieve the coupling process described with respect to FIG. 14I, including at least some of the coupling techniques described in the paper cited above by Pasquariello et al. Can be used.

  FIG. 14J shows the result of performing the next step of this series of processes (the step of reducing the thickness of the p-type substrate 50 to a desired thickness when the thickness needs to be reduced). This is done by polishing the exposed backside of the substrate 50 to about 50 μm, or by cleaving, or by other means.

  FIG. 14K shows the result of performing the next step of this series of processes (the step of forming the n-type layer 51 on the substrate 50 by ion implantation). Thereafter, as shown in FIG. 14L, the final CMOS process is performed. These final steps can also include protective film formation, contact formation (or completion of the contact formation process), and mounting of the light shield 54 in place.

  In order to use the final structure shown in FIG. 14L, it is necessary to make contacts extending from each of layers 41, 46, and 51 to the exposed (top) surface of this structure. This contact is preferably formed by any of the methods described herein. As described in application 09 / 884,863, with reference to FIGS. 15-15H, we now describe one suitable technique for forming such contacts.

  The technique described with reference to FIGS. 15A-15H preferably uses a trench etcher of the type typically used in high performance analog bipolar (or DRAM) processes to form low leakage current trench contacts.

  FIG. 15A shows the result of performing the first step of the series of processes (step of etching the trench through the silicon layers 50 and 51 having the structure of FIG. 14L up to the insulating layer 49).

Next, as shown in FIG. 15B, a suitable etch process (eg, an oxide etch process when layers 47, 48, and 49 are comprised of SiN or SiO ₂ ) extends the trench to silicon layer 45. Next, as shown in FIG. 15C, the silicon etch process extends the trench to the insulating layer 44. Next, as shown in FIG. 15D, a suitable etch process (eg, an oxide etch process when layers 44, 43, and 42 are comprised of SiN or SiO ₂ ) extends the trench to silicon layer 40.

  Next, as shown in FIG. 15E, a time etch process of silicon extends the trench to the n-type silicon cathode layer 41 (the cathode of the red sensor).

Next, as shown in FIG. 15F, the trench is covered with an insulating layer, preferably by growing a SiO ₂ overcoat layer 301 on all exposed surfaces of the trench. Next, as shown in FIG. 15G, anisotropic etching is performed on the cathode layer 41 to remove the insulating film from only the bottom of the trench and expose the n-type silicon material of the cathode layer 41.

  Finally, as shown in FIG. 15H, the trench is filled with n-type polysilicon material, completing the trench contact to layer 41. The top of the trench contact can be coupled directly to the bias and readout circuitry (eg, to the gate of the source follower amplification transistor of FIG. 2A).

  In a section of solid material in which the inventive VCF sensor group is formed, a trench can be formed and filled with a semiconductor material to form contacts to the cathode and anode of the buried sensor. For example, it is possible to dope a semiconductor material around the trench, and then a protective layer can be grown on the doped layer of the trench, and then the bottom of the trench can be opened, after which the opened trench is an n-type semiconductor (Eg, n + polysilicon) so that it functions as an n-type contact to the buried n-type cathode. Alternatively, such trenches are covered and / or filled with an insulating material, separating the VCF sensor groups from each other. The trench contact (or insulating structure) can be made much narrower than the plug contact formed by diffusion, as described in application number 09 / 884,863. A trench having a cross-sectional area of 0.5 μm and a depth of 2 to 3 μm can be easily formed using existing techniques for forming a trench contact to a deep sensor of a typical VCF sensor group. Such a cross-sectional area is much smaller than the minimum cross-sectional area of a diffusion plug contact (having the same depth) that can be inexpensively formed using existing technology. The use of trench contacts (or trench isolation structures) allows the horizontally separated VCF sensor groups in the sense that incident light can increase the area of the image plane that can be detected by the sensors of the VCF sensor group. The fill factor of the array can be improved (and the area of the image plane occupied by structures that are blocked by the radiation shield or do not convert incident light into detectable electrons or holes can be reduced) .

  In a preferred embodiment, a multi-stage ion implantation process that forms a diffusion plug contact having a cross-sectional area that is much smaller than the minimum cross-sectional area of the diffusion plug contact (having the same depth) than can be inexpensively formed using existing techniques. Thus, at least one plug contact is formed in the VCF sensor group. As shown in FIG. 17, the “red” sensor n (at a depth of about 2.6 μm below the top surface of the sensor group completed at about 2 μm below the n-type cathode of the “green” sensor). The n-type plug contact to the p-type cathode is to the exposed surface of the p-type silicon (at a depth of about 1.3 μm from the top surface of the finished sensor group) to form the bottom of this contact (at 1200 KeV) It can be formed by prior art ion implantation of phosphorus (with energy). After that, an additional structure (including a p-type silicon epi layer) is formed on the exposed surface, and then phosphorus is ion-implanted (with 500 KeV energy) into the new exposed surface of the p-type silicon to form the top of the contact. To do. However, as also shown in FIG. 17, this results in contacts with an undesirably large diameter (diameters of about 2.2 μm or more depending on the amount of n-type doping used and the number of heat treatment cycles in the process). In addition, because a thick (eg, 3 μm) photoresist layer needs to be placed over the sensor group (to prevent high energy (eg, 1200 KeV) phosphorus ion implantation from reaching undesired regions of the sensor group). Therefore, it is necessary to minimize the size of the shape of the sensor group that can be formed.

  In contrast to the technique used to make the contact of FIG. 17, we now describe an embodiment of a multi-stage ion implantation process performed in accordance with the present invention (see FIGS. 18 and 18A). The multi-stage ion implantation process of the present invention of FIGS. 18 and 18A is such that a target (eg, consisting of the cathode 310 of the red sensor of FIG. A contact having a diameter of about 0.5 μm that is formed and extends to a target at a depth of about 2 μm in the sensor group. This process includes four steps.

  The first step is to form a first epitaxial layer (epi layer) on the target where the contact extends. (For example, as shown in FIG. 17, a p-type silicon layer 311 is formed on the cathode 310 of the photodiode).

  Thereafter, the bottom portion of the plug (eg, plug portions 312 and 313 in FIG. 18) is formed by ion implantation into the first epilayer (311). To do so, the layer 311 has a thickness of about 1 μm so that the bottom of the plug needs to extend through the layer 311 only a short distance (1 μm) in the normal case where a thin nitride mask 314 is on the layer 311. A small mask opening 318 (having a diameter of about 0.5 μm) is then formed in the mask 314, after which arsenic is ion implanted through the opening 318. Using such a mask and such first epi layer thickness, the first portion 312 at the bottom of the plug (extending from layer 310 to about 0.7 μm above layer 310) into layer 311 at an energy of 1200 KeV. It can be formed by ion implantation of arsenic. Thereafter, a second portion 313 at the bottom of the plug (extending about 0.3 μm from the portion 312 to the top surface of the layer 311) can be formed on the portion 312 by ion implanting arsenic into the layer 311 with an energy of 500 KeV. .

  An advantage of ion implanting an element (eg, arsenic) having a lower diffusion coefficient than phosphorus according to the present invention is that a much thinner mask can be used, as is apparent from the survey results of FIG. FIG. 19 is a graph of the mask thickness required during normal ion implantation of boron, phosphorus, arsenic, and antimony for each of the five shown mask materials. For example, FIG. 19 shows that a Si3N4 mask with a thickness of about 0.07 μm can be used for arsenic ion implantation (at 100 KeV), while a Si3N4 mask with a thickness of 0.15 μm can be used for phosphorus ion implantation with the same energy. Is called.

  In the third step, the mask 314 is removed from the first epi layer 311, and then a second epi layer on the first epi layer 311 (the epi layer of FIG. 18A and made of p-type silicon) is formed. It is a process.

  The top portion of the plug (eg, plug portions 316 and 317 in FIG. 18A) is then formed by ion implantation in the second epilayer (315). To do so, the layer 315 has a thickness of about 1 μm so that the top portion of the plug needs to extend through the layer 315 by a short distance (1 μm) in the normal case where a thin nitride mask 319 is applied over the layer 315. A small mask opening 320 (having a diameter of about 0.5 μm) is made in the mask 319, after which arsenic is ion implanted through the opening 320. With such a mask and the thickness of such an epi layer, the first portion 316 at the bottom of the plug (extending from layer 311 to about 0.7 μm on layer 311) is applied to layer 315 at an energy of 1200 KeV. The first portion 317 at the bottom of the plug (which extends about 0.3 μm from portion 316 to the top surface of layer 315) can then be formed by ion implanting arsenic into layer 315 at an energy of 500 KeV. Can be formed on the portion 316.

  More generally, diffused plug formation using an element having a lower diffusion coefficient (preferably arsenic ("As") rather than conventional phosphorus ("P")) than the diffusion coefficient of phosphorus of embodiments of the present invention. The ion implantation process necessary for the above is performed. Such elements (having a low diffusion coefficient) have less horizontal diffusion than phosphorus. As a result, a narrower plug can be formed, and the sensor group can improve the fill factor. Although arsenic has a much lower diffusion coefficient (both longitudinal (vertical) and lateral) than phosphorus, the multistage ion implantation process of the present invention (a typical example of which is shown in FIGS. 18, 18A and 19). It is practical to ion implant arsenic (rather than phosphorus) to form a diffusion plug. This is not the case over long distances (eg, anywhere from the top of the sensor group to the buried target where the contact is extended) as in conventional methods of forming diffusion plugs, but arsenic can be This is because a relatively short distance is diffused vertically through the layers.

  As a variation on the multi-stage ion implantation process described above (see FIGS. 18, 18A, and 19), three or more epilayers are used on low diffusion coefficient elements and / or targets other than arsenic. A diffused portion of the contact is formed in each epi layer.

  When creating VCF sensor groups on a wafer, at least one transistor (for using one or more sensors of each VCF sensor group for coupling) is placed on the “bottom” surface of the wafer (the group on which the light to be sensed is incident. On the surface opposite to the “top” surface of The formation of such transistors on the bottom surface of the wafer (rather than the top surface of the group) improves the fill factor of the array of horizontally separated VCF sensor groups. In many different embodiments of the inventive VCF sensor group and array of VCF sensor groups, transistors can also be formed on the bottom surface of the wafer.

  An example of a method of forming a VCF sensor group on a wafer having transistors on the bottom surface of the wafer will be described with reference to FIGS. 16A-16H. FIGS. 16A-16H assume that the structure including elements 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, and 51 (shown in FIG. 16A) is formed in advance. . This structure is identical to that shown in FIG. 14K and is referred to as the “main” structure. The description of the main structure and the method of making it will not be repeated.

  As shown in FIG. 16A, a “process” wafer comprising a p-type semiconductor substrate material 91 and an insulating layer 90 on the substrate 91 then has a main structure layer 50 that faces the insulating layer 90 of the processed wafer. Adapted with structure.

  Thereafter, as shown in FIG. 16B, the layer 90 of the processing wafer is bonded to the exposed (top) surface of layer 50 (preferably by a thermal bonding process), and layer 90 is formed of p-type semiconductor layer 50 and p. Sandwiched between the mold semiconductor substrates 91.

  The exposed bottom surface of the substrate 40 is then polished to reduce its thickness (as shown in FIG. 16C). As a result, a sensor (including the red sensor cathode layer 41, the green sensor cathode layer 46, and the blue sensor cathode layer 51) accessible from the bottom can be created. The resulting structure can then be reversed so that the exposed “bottom” surface of the polished element 40 is the top surface of FIG. 16C. As shown in FIG. 16D, a trench contact (96) is then formed extending from the exposed “bottom” face of element 40 (at the top of FIG. 16D) to the blue sensor cathode layer 51. This can be done in the manner described with reference to FIGS. 15A-15H. Support circuitry 92 is then formed on the exposed “bottom” face of element 40, preferably by a semiconductor integrated circuit fabrication process. Support circuit 92 includes at least one transistor coupled to the bottom of trench contact 96 (at the top of FIG. 16D). Another trench contact (not shown) is formed from the exposed bottom surface of element 40 to the green sensor cathode layer 46, and a third trench contact (not shown) is formed from the exposed bottom surface of element 40 to the red sensor cathode. Layers 41 are formed. At least one transistor of support circuit 92 is coupled to layers 41, 46, and 51 via a trench contact.

  As shown in FIG. 16E, a second “process” wafer comprising p-type semiconductor substrate material 94 and insulating layer 93 on substrate 94 exposed p-type semiconductor substrate of element 92 facing insulating layer 93 (see FIG. 16E). The bottom) plane is used to match the structure of FIG. 16D.

  Thereafter, as shown in FIG. 16F, the layer 93 of the second processing wafer is bonded to the exposed surface of the element 92 (preferably by a low temperature bonding process), and the layer 93 is bonded to the p-type semiconductor substrate of the element 92 and It is sandwiched between p-type semiconductor substrates 94.

  Thereafter, substrate 91 is removed (eg, polished) and the structure of FIG. 16F is inverted (so that the exposed bottom surface of substrate 94 is faced down and the exposed top surface of layer 90 is in FIG. 16G. Face up as shown).

  Support circuit 92 is then coupled to a bias and readout circuit. For example, as shown in FIG. 16H, the support circuit 92 is coupled to the bias and readout circuit by a shell case structure 95, and the device connects between the transistors of the support circuit 92 and the circuit 96. Industrially used methods (e.g., methods developed by Shell Case Company) can be used to make the shell case structure 95. The bias and readout circuit 96 is of the type described with reference to FIG. 2A.

  Another way to create isolation (eg, between adjacent VCF sensor groups) is to use a blocking MOS transistor as the isolation structure. This can be done using a thick oxide transistor (the gate is held at a voltage well below the threshold) or another kind of MOS transistor with a gate surrounding the top layer of the sensor group to be isolated. Therefore, in order to separate adjacent VCF sensor groups from each other, it can also be applied in combination with a separation method of the type described above with reference to FIGS. 20-24.

  An example of the isolation method described in the previous paragraph is ring isolation, which is realized by forming a thick or thin oxide MOS transistor that surrounds the top layer of the sensor group from which the gate is isolated. it can. During operation, its gate is biased to shut off the transistor.

  Any of several available methods can be used to create a VCF sensor group. Also, the best method for each case depends on the materials and conditions for the sensor group.

  The silicon structure can be constructed using epi growth and ion implantation, as described by way of example in US patent application Ser. No. 09/884863 referenced above. Ion implantation provides a method for forming a junction structure under a silicon surface. Deep structures are possible using high energy (> 400 KeV) ion implantation. VCF sensors typically require a thicker silicon structure than can be made using high energy ion implantation, so epi-growth combined with ion implantation usually involves photons (photons) in deep electrons in the silicon. Used to create the deep structure needed to capture photons (in accordance with the present invention) by converting to / hole pairs.

Another method used to create deep structures in some embodiments of the invention is silicon bonding. The method is to bond a layer of semiconductor or insulating material to another at the molecular level. For example, it is possible to create a structure in a silicon wafer and then bond a thin layer of silicon on top of it. It is also possible to bond dissimilar semiconductors. For example, a III-V semiconductor can be bonded to silicon using a suitable material. Due to the difference in expansion coefficients of the two materials, the island of III-V material on the silicon portion cannot be large. However, an island of III-V material that is large enough to form an exemplary embodiment of the VCF sensor group of the present invention (eg, In _x Ga _1-x N material discussed above with reference to FIG. 7). Can be bonded to silicon. An important advantage of doing so is that silicon (eg, silicon has a significant absorption coefficient for green light and a larger absorption coefficient for green light than for red light, but is a group III-V The material can be selected to absorb light in a different wavelength band (which transmits all or substantially all green and red incident light). As a result, it is possible to produce a group of sensors, each sensor formed from a III-V material in a different wavelength band than each sensor formed from silicon based on a III-V material. Absorbs light.

  To add a filter (eg, a VCF color filter) to the vertical structure, a trench (or other cavity) is formed in the semiconductor material portion and then the filter material that is a liquid or other fluid (eg, slurry) It is possible to fill the space. One way to accomplish this is to use lateral silicon overgrowth to form cavities in the semiconductor material portion, and then etch away the oxide (which exists during the lateral silicon overgrowth process). That is. An etchant such as hydrofluoric acid can be used for this etching step. When the cavity is formed under silicon, it can be filled with a liquid optical filter material (or with an optical filter material that is a fluid other than a liquid). This filter material is solidified (eg, by heat treatment or UV treatment) to form a VCF sensor cluster structure. Alternatively, the oxide film region can be formed by a reaction step of forming SiO2 (silicon dioxide film) from the reaction between the oxygen ion-implanted and oxygen implanted into the wafer.

  The process described in the previous paragraph will now be described in further detail with reference to FIGS. FIG. 13a shows a SiO2 region 170 formed on the surface of a p-type semiconductor 171 (which can be silicon) and an ion-implanted n-type semiconductor region 172 that forms a pn junction under the SiO2 region 170. Show. The ion-implanted region 172 becomes one of the sensors of the VCF sensor group. FIG. 13b also shows a first plug ion implantation (of n-type semiconductor material) extending upward from the right edge of region 172. FIG.

  FIG. 13b shows the same cross-section after lateral epi growth over the SiO2 region 170 using an additional p-type semiconductor material 171 of the same type as the semiconductor 171 of FIG. 13a (which can also be silicon). Indicates. Lateral epi-growth has been used in the semiconductor industry to produce isolated single crystal silicon. As shown in FIG. 13c, a near surface ion implant (of n-type semiconductor material) is then formed over the SiO2 region 170 and a second plug ion implant (of n-type semiconductor material) is formed of the first plug ions. It is formed so as to extend upward from the implantation to the uppermost surface of the semiconductor 171. The two plug ion implantations together form a plug contact for coupling layer 172 to the bias and readout circuit.

As shown in FIG. 13d, the next step is to etch away material 171 sufficiently to form a trench that exposes the underlying SiO ₂ region 170. FIG. Thereafter, it is performed to remove the oxide film (this SiO ₂ ) from the region 170, leaving a cavity under the top layer 173 as shown in FIG. 13e. Finally, the cavity is filled with liquid filter material 174 (as shown in FIG. 13f) and material 174 is solidified. Alternatively, the filter material 174 may be a fluid other than a liquid.

  Variations on the method described with reference to FIGS. 13a-13f have two or more vertically separated sensors under the filter area (filled with filter material 174) to form a VCF sensor group. Can be used for

  In some embodiments of the VCF sensor group of the present invention, a semiconductor material other than crystalline silicon is deposited on a wafer or other substrate. Two examples of such semiconductor materials are amorphous silicon and polysilicon.

  Amorphous silicon can be deposited by various chemical vapor deposition and sputtering techniques. Amorphous silicon can also be deposited with high quality by plasma-assisted chemical vapor deposition using SiH as the source gas. Laminated amorphous silicon doping can be achieved by adding small amounts of other hydrides such as phosphine, arsine and diborane. Amorphous silicon can be used in VCF sensor groups as sensors (by making pin diodes in amorphous silicon), as filters, or as sensors and filters. Amorphous silicon can also be used in photoimaging arrays. Low temperatures (less than 400 ° C.) for laminating amorphous silicon are advantageous. This is because it only slightly increases the diffusion of the dopant and is compatible with some filters.

  In a similar manner, the semiconductor material can form polysilicon on a wafer or other substrate. Usually, amorphous silicon is laminated and then recrystallized to form polysilicon. Polysilicon is doped by ion implantation or from a deposited layer to create a pn junction. Transistors can be formed in either amorphous silicon or polysilicon, and can also be used to address the sensors in the VCF sensor group.

  Various filters and filter combinations can also be included in the VCF sensor group of the present invention to improve photon separation, color accuracy, and sensor resolution. For example, an array of VCF sensors can be combined with an organic color filter of the type commonly used in image sensor fabrication. It is possible to form (or include) a filter on part of the sensor group of the array with a checkerboard pattern that adjusts the color response of the sensor group sensitive to blue and red illumination. Thanks to the fact that the filter functions in conjunction with the semiconductor color filter characteristics of each VCF sensor group using such a filter pattern, the characteristics of each filter can be greatly simplified and insensitive to manufacturing changes. Can be. This gained advantage is potentially more enhancing the color filter response. Alternatively, organic, insulating, or polysilicon filters can be placed on (or included in) part of the array's VCF sensor group and any other that responds to a particular color. The sensor group also has a color filter that serves to shape its color response, resulting in an array with six different color responses. The latter technique places an organic filter (or other type of filter) on top of the image sensor surface, minimizing manufacturing costs associated with processes involving filters in the VCF sensor group, while providing a wide variety of color responses. Enable.

While the invention and the best way of carrying out the application of the invention have been described herein, many variations on the embodiments and applications described herein depart from the scope of the invention described and claimed herein. It will be apparent to those skilled in the art that this is possible without. While some forms of the invention have been illustrated and described, it is also understood that the invention is not limited to the specific embodiments or specific methods described and illustrated. . Further, unless stated explicitly in a claim statement, a claim that describes a method does not imply any particular order of steps.

FIG. 1 is a graph of electromagnetic radiation intensity (relative to incident intensity I ₀ ) in crystalline silicon as a function of silicon depth (in microns) for wavelengths 450 nm, 550 nm, and 650 nm. FIG. 2 is a diagram showing a vertical doping profile for a group of VCF sensors embodying the present invention. FIG. 2A is a cross-sectional view (in the vertical plane) of the VCF sensor group whose profile is shown in FIG. 2 and includes a schematic circuit diagram of a bias and readout circuit coupled to the sensor group. 3, with respect to wavelength 450 nm (curve A), 550 nm (curve B), and 650 nm (curve C), as a function of silicon depth (microns), on the absorption rate (incident intensity I ₀ of the electromagnetic radiation in crystalline silicon ), And the positions of the layers of the sensor group in FIG. 2 overlaid (covered) thereon are also shown. FIG. 4 is a graph of the spectral sensitivity of three photodiodes in a sensor group whose profile is similar to that shown in FIG. FIG. 5 is a simplified cross-sectional view (in the vertical plane) of an embodiment of the VCF sensor group of the present invention. FIG. 6 lists the electron gap bandgap energy of In _x Ga _1-x N semiconductors with different levels of indium content and the optical wavelength (in the right column) corresponding to each bandgap energy. It is a table. FIG. 7 is a cross-sectional view of an avalanche sensor that can be included in an embodiment of the VCF sensor group of the present invention. FIG. 8 is a cross-sectional view of a portion of an array of VCF sensor groups of the present invention, each sensor group of the array including two non-sensor filters and three sensors. FIG. 8A is a simplified top view of a portion of an array of VCF sensor groups of the present invention, where each group containing a filter is marked with an “X”. FIG. 8B is a simplified top view of a portion of another array of VCF sensor groups of the present invention, where each group containing a filter is marked with an “X” mark. FIG. 9 is a cross-sectional view of a portion of an array of VCF sensor groups of the present invention, where a microlens is formed on each sensor group of the array. FIG. 10 is a simplified top view of a portion of the array of VCF sensor groups of the present invention, where adjacent sensor groups share a carrier collection element. FIG. 10A is a cross-sectional view (in the vertical plane) of two VCF sensor groups in the array, where the two sensor groups share common sensor elements. FIG. 10B is a top view of the four VCF sensor groups in the array, where the four sensor groups share a carrier collection region to collect carriers photoexcited by absorption of red and blue photons. FIG. 11 is a cross-sectional view (in a vertical plane) of a portion of a conventional sensor array. FIG. 12 is a cross-sectional view (in a vertical plane) of a portion of the array of VCF sensor groups, with a trench isolation structure between adjacent sensor groups of the array. 13a to 13f are cross-sectional views (in the vertical plane) of structures formed in various manufacturing steps of the embodiment of the VCF sensor group of the present invention. 14A-14L are cross-sectional views (in the vertical plane) of structures formed in various manufacturing steps of another embodiment of the VCF sensor group of the present invention. 15A-15H are cross-sectional views (in the vertical plane) of structures formed in various manufacturing steps of another embodiment of the VCF sensor group of the present invention. 16A-16H are cross-sectional views (in the vertical plane) of structures formed in various manufacturing steps of another embodiment of the VCF sensor group of the present invention. FIG. 17 is a cross-sectional view (in a vertical plane) of the structure formed during manufacture of an embodiment of the VCF sensor group, including plug contacts formed by an ion implantation process. Each contour line (representing the boundary between p-type and n-type material) shows the result of forming a plug contact with a different type of doping level, the smallest with the first ("1x") n-type doping level It has an n-type region, a maximum n-type region with twice this ("2x") doping level, and an intermediate-sized n-type region with an intermediate ("1.4x") doping level. FIG. 18 is a cross-sectional view (in the vertical plane) of the structure formed during manufacture of a preferred embodiment of the VCF sensor group of the present invention, with the plug (formed during the initial steps of the multi-stage ion implantation process). Includes the bottom portion of the contact. 18A is a cross-sectional view (in the vertical plane) of a structure formed from the structure of FIG. 18 during manufacture of a preferred embodiment of the VCF sensor group of the present invention, with the bottom portion shown in both FIGS. 18 and 18A. The upper portion of the plug contact (formed during the subsequent steps of the multi-stage ion implantation process). FIG. 19 is a graph of the mask thickness required during boron, phosphorus, arsenic, and antimony ion implantation for each of the five shown mask materials. FIG. 20 is a simplified cross-sectional view (in the vertical plane) of an embodiment of the inventive VCF sensor group that includes a blanket barrier layer between two sensors. FIG. 21 is a graph of dopant concentration as a function of depth in the sensor group of FIG. FIG. 22 is a simplified cross-sectional view (in the vertical plane) of a variation on the sensor group of FIG. 20, including conventional blanket barrier ion implantation rather than the blanket barrier layer 205 of the present invention. FIG. 23 is a graph of dopant concentration as a function of depth in the sensor group of FIG. FIG. 24 is a simplified cross-sectional view (in the vertical plane) of another embodiment of the inventive VCF sensor group, with a blanket barrier layer (205) and additional blanket barrier ion implantation (207 and 208). FIGS. 25A-25D are cross-sectional views (in the vertical plane) of structures formed in various steps of a self-aligned complementary ion implantation process during manufacture of embodiments of the VCF sensor group of the present invention.

Claims (41)

A block of solid material having a readout surface on which at least two vertically stacked sensors are formed, each of the sensors having a different spectral response, the sensor including a layer of semiconductor material and functioning as a photodiode A block characterized in that it is made biased and a trench contact between one of the sensors and the readout surface, wherein one of said sensors comprises a semiconductor material having a first polarity A trench contact, characterized in that the contact is a trench covered or filled with a semiconductor material having a first polarity,
A sensor group including   The sensor group according to claim 1, wherein the contact is coated with a semiconductor material having a first polarity.   Sensor group according to claim 1, characterized in that the contacts are filled with a semiconductor material having a first polarity.   The sensor group of claim 1, wherein the block has a top surface through which sensed radiation can propagate and the readout surface is the top surface. A method of manufacturing a vertical color filter sensor group, comprising: (a) providing a semiconductor substrate; and (b) forming a structure including at least two vertically stacked sensors on the semiconductor substrate.
Each of the sensors has a different spectral response, all the sensors are configured to collect photo-excited first polarity carriers, each of the sensors includes at least one first conductivity type carrier collecting semiconductor layer; Step (b) includes forming a trench contact to the carrier collection layer of at least one sensor and forming at least one filter in the structure, wherein the filter propagated through or reflected from the filter. A manufacturing method comprising a layer laminated with a sensor at a position where radiation propagates to at least one sensor. A block of solid material having a top surface and a bottom surface through which sensed radiation can propagate, wherein at least two vertically stacked sensors are formed, each of the sensors having a different spectral response, the sensor comprising a layer of semiconductor material A block characterized in that it is configured to be biased to function as a photodiode, and at least one transistor formed on the contact and bottom surface between one of the sensors and the bottom surface, One of the sensors has a carrier collection region comprising a semiconductor having a first polarity, and the contact is a trench covered or filled with a semiconductor material having a first polarity; and Transistor,
Sensor group including   The sensor group according to claim 6, wherein the transistor is formed on the bottom surface by a semiconductor integrated circuit manufacturing process.   The sensor group of claim 6 including a bias and readout circuit coupled to the transistor.   Sensor group according to claim 6, characterized in that the contacts are filled with a semiconductor material having a first polarity.   7. The sensor group according to claim 6, wherein the contact is coated with a semiconductor material having a first polarity. (A) providing a block of solid material having a top surface and a bottom surface through which sensed radiation can propagate; and (b) at least one semiconductor integrated to the block to form a structure including at least two vertically stacked sensors. Applying a circuit;
A vertical color filter sensor group manufacturing method including:
The structure includes at least two vertically stacked sensors, each sensor having a different spectral response, the sensor includes a semiconductor material layer, the sensor is made biased to function as a photodiode, and the sensor Comprising a contact between one of the sensors and the bottom surface and at least one transistor formed on the bottom surface, wherein one of the sensors has a carrier collection region comprising a semiconductor having a first polarity;
Further, step (b) includes forming a trench between one of the sensors and the bottom surface, and covering or filling the trench with a semiconductor having a first polarity,
Production method.   12. The manufacturing method according to claim 11, wherein the step (b) includes a step of filling the trench with a semiconductor material having a first polarity.   12. The method according to claim 11, wherein the step (b) includes a step of covering the trench with a semiconductor material having a first polarity. (A) A method for manufacturing a vertical color filter sensor group, including a step of forming a structure including at least two vertically stacked photosensitive sensors,
Each of the sensors has a different spectral response, and step (a) further comprises
(B) forming a first epitaxial layer at the stage of manufacturing one part of the structure;
(C) ion implantation to form a first portion of the plug contact in the first epitaxial layer;
(D) after step (c), forming a second epitaxial layer on the first epitaxial layer; and (e) forming a second portion of the plug contact in the second epitaxial layer. Ion implantation process,
The manufacturing method characterized by including.   The manufacturing method according to claim 14, wherein the step (c) includes a step of ion-implanting a substance having a diffusion coefficient significantly smaller than phosphorus in the first epitaxial layer.   15. The manufacturing method according to claim 14, wherein the first epitaxial layer consists essentially of p-type silicon, and step (c) includes the step of ion-implanting arsenic into the first epitaxial layer.   The method according to claim 16, wherein the second epitaxial layer consists essentially of p-type silicon, and step (e) includes the step of ion-implanting arsenic into the second epitaxial layer.   At least one sensor includes a carrier collection layer consisting essentially of n-type silicon, a portion of the structure fabricated includes the carrier collection layer, and step (c) includes the first portion of the plug contact as a carrier. The manufacturing method according to claim 14, comprising a step of performing ion implantation so as to reach the collection layer.   Step (a) includes forming at least one filter in the structure, wherein the filter is laminated with a sensor in a position such that radiation propagated through or reflected from the filter propagates to the at least one sensor. The manufacturing method according to claim 14, wherein the manufacturing method is a formed layer. At least two vertically laminated photosensitive sensors formed on a semiconductor substrate;
A first epitaxial layer on one of the sensors;
Having a second epitaxial layer on the first epitaxial layer, a bottom portion extending through the first epitaxial layer to one of the sensors, and an upper portion extending from the bottom portion through the second epitaxial layer; Plug contact,
Sensor group including   Each of the first epitaxial layer and the second epitaxial layer is essentially made of p-type silicon, the bottom portion of the plug contact is a region of the first epitaxial layer in which arsenic is diffused, and the top portion of the plug contact is arsenic. 21. Sensor group according to claim 20, characterized in that is a region of the diffused second epitaxial layer. A sensor group formed on a semiconductor substrate having a first polarity,
The sensor group includes:
At least two vertically stacked sensors, each of which has a different spectral response, can be biased to function as a photodiode, and includes a carrier collection layer of semiconductor material having a second polarity. And is configured to collect photoexcited carriers of a second polarity when biased to function as a photodiode, wherein the second polarity is opposite to the first polarity and the first at least One sensor includes a first reference volume of a semiconductor material having a first polarity, and the second at least one sensor includes a second reference volume of a semiconductor material having a first polarity, the first reference The volume and the second reference volume are located between one of the first sensors and one carrier collection layer of the second sensor, and the first reference volume and the second reference volume. The volume is made to collect and conduct photoexcited carriers of a first polarity when the sensor is biased to function as a photodiode, and a first reference volume and a first reference volume A separation layer of semiconductor material having a first polarity and having a higher doping amount than either the first reference volume or the second reference volume, present between the two reference volumes;
A sensor group comprising:   The first reference volume and the second reference volume are portions of the p-type semiconductor block, and the separation layer is a portion of the title block of the p-type semiconductor doped as a result of the ion implantation process. The sensor group according to claim 22. One of the first sensors also includes a third reference volume of semiconductor material having a first polarity and disposed laterally with respect to one carrier collection layer of the first sensor;
The sensor group also includes an additional separation volume of a semiconductor material having a first polarity but more doped than the third reference volume, the third reference volume being an additional separation volume and the first sensor volume. Exists between one carrier collection layer,
The sensor group according to claim 22, wherein:   23. Sensor group according to claim 22, characterized in that it comprises at least one filter arranged relative to the sensor such that the radiation propagated through or from the filter is propagated to the at least one sensor. An array of sensor groups formed on a semiconductor substrate having a first polarity,
Each of the sensor groups
At least two vertically stacked sensors, each of which has a different spectral response, can be biased to function as a photodiode, and includes a carrier collection layer of semiconductor material having a second polarity. And is configured to collect photoexcited carriers of a second polarity when biased to function as a photodiode, the second polarity being opposite to the first polarity and at least one sensor Includes a first reference volume of semiconductor material having a first polarity, and the second at least one sensor includes a second reference volume of semiconductor material having a first polarity, the first reference volume and the first reference volume The two reference volumes are located between one carrier collection layer of one of the first sensors and one of the second sensors, the first reference volume and the second reference volume A vertically stacked sensor configured to collect and conduct photoexcited carriers of a first polarity when the sensor is biased to function as a photodiode, and a first reference volume and a second A separation layer of semiconductor material having a first polarity and having a higher doping amount than either of the first reference volume and the second reference volume, disposed between the reference volumes;
A sensor group array comprising:   The first reference volume and the second reference volume are portions of the p-type semiconductor block, and the separation layer is a portion of the title block of the p-type semiconductor doped as a result of the ion implantation process. The sensor group array according to claim 26. One of the first sensors also includes a third reference volume of semiconductor material having a first polarity and disposed laterally with respect to one carrier collection layer of the first sensor;
The sensor group also includes an additional separation volume of a semiconductor material having a first polarity but more doped than the third reference volume, the third reference volume being an additional separation volume and the first sensor volume. Exists between one carrier collection layer,
23. The sensor group array according to claim 22,   Characterized in that it comprises at least one filter arranged with respect to the sensors of at least one sensor group so that the radiation propagated through or from the filter propagates to at least one sensor of one of said sensor groups, 27. The sensor group array according to claim 26. (A) providing a semiconductor substrate having a first polarity; and (b) forming a structure on the substrate, the structure including at least two vertically stacked sensors, each of the sensors comprising: Characterized in that it includes a carrier collection region of a semiconductor material having a different spectral response and a second polarity and is configured to collect photoexcited carriers of a second polarity when biased to function as a photodiode. The second polarity is opposite to the first polarity, the first at least one sensor includes a first reference volume of semiconductor material having the first polarity, and the second at least one sensor is the first And a first reference volume and a second reference volume located between one of the first sensors and one carrier collection layer of the second sensor. And wherein the first reference volume and the second reference volume are configured to collect and conduct photoexcited carriers of the first polarity when the sensor is biased to function as a photodiode. The process of
A method for producing a sensor group including:
Step (b) has a first polarity that exists between the first reference volume and the second reference volume, and has a higher doping amount than either the first reference volume or the second reference volume. A manufacturing method comprising a step of performing ion implantation to form a separation layer of a semiconductor material. (A) providing a semiconductor substrate having a first polarity; and (b) forming a structure on the substrate, the structure including a plurality of sensor groups, each sensor group comprising at least two sensor groups. Including vertically stacked sensors, each of the sensors having a different spectral response, including a carrier collection layer of a semiconductor material having a second polarity, and a second polarity photoexcited carrier when biased to function as a photodiode The second polarity is opposite to the first polarity, and the first at least one sensor in each sensor group is a first of the semiconductor material having the first polarity. And the second at least one sensor in each sensor group includes a second reference volume of the semiconductor material having the first polarity, and the first reference volume and the second reference volume. And the second reference volume is located between one of the first sensors and one carrier collection layer of the second sensor, and the first reference volume and the second reference volume function as a photodiode. And is configured to collect and conduct photoexcited carriers of a first polarity when biased for,
A method for producing a sensor group array comprising:
Step (b) includes performing ion implantation to form a semiconductor material isolation layer in each sensor group, the isolation layer having a first polarity and having a first reference volume and a second reference volume. A manufacturing method characterized in that the amount of doping is larger than any one of the above and located between the first reference volume and the second reference volume. A sensor group array formed on a semiconductor substrate including a first sensor group, a second sensor group, and a separation region between the first sensor group and the second sensor group,
The first sensor group includes at least two vertically stacked sensors, each sensor of the first sensor group has a different spectral response and can be biased to function as a photodiode, Comprising a carrier collection layer of a polar semiconductor material, characterized in that it is configured to collect photoexcited carriers of a first polarity when biased to function as a photodiode;
The second sensor group includes at least two vertically stacked sensors, each sensor of the second sensor group has a different spectral response and can be biased to function as a photodiode, Comprising a carrier collection layer of a polar semiconductor material, characterized in that it is configured to collect photoexcited carriers of a first polarity when biased to function as a photodiode;
The isolation region includes a semiconductor material having a second polarity between the first sensor group and the second sensor group, the second polarity is opposite to the first polarity, and the isolation region is at least one isolation Characterized by defining trenches,
Sensor group array.   33. The sensor group array of claim 32, wherein the isolation trench is at least partially filled with a semiconductor material having a second polarity and is more doped than the remainder of the isolation region.   The sensor group array according to claim 32, wherein the isolation trench is surrounded by a semiconductor material having a second polarity and has a higher doping amount than the remaining portion of the isolation region.   33. The sensor group array of claim 32, wherein the isolation trench is at least partially filled with an insulating material.   The sensor group array according to claim 32, wherein the isolation trench has a covering layer of an insulating material. (A) providing a semiconductor substrate; (b) forming a structure on the substrate, the structure including a first sensor group and a second sensor group, wherein the first sensor group and the second sensor group; Each of the sensor groups includes at least two vertically stacked sensors, each of which includes a carrier collection layer of semiconductor material having a different spectral response and having a first polarity, and further biased to function as a photodiode. Being configured to collect photoexcited carriers of a first polarity when
A method for producing a sensor group array comprising:
Step (b) includes producing an isolation region including a semiconductor material having a second polarity between the first sensor group and the second sensor group, the second polarity being opposite to the first polarity. Wherein the isolation region defines at least one isolation trench,
Production method.   38. Step (b) includes at least partially filling the isolation trench with a semiconductor material having a second polarity, wherein the isolation trench is more doped than the remainder of the isolation region. The manufacturing method as described in.   38. A method according to claim 37, wherein step (b) includes the step of at least partially filling the isolation trench with an insulating material.   38. The method of claim 37, wherein step (b) includes at least partially covering the isolation trench with an insulating material. A sensor group array formed on a semiconductor substrate including a first sensor group, a second sensor group, and a separation region between the first sensor group and the second sensor group,
The first sensor group includes at least two vertically stacked sensors, each sensor of the first sensor group has a different spectral response and can be biased to function as a photodiode, Comprising a carrier collection layer of a polar semiconductor material, characterized in that it is configured to collect photoexcited carriers of a first polarity when biased to function as a photodiode;
The second sensor group includes at least two vertically stacked sensors, each sensor of the second sensor group has a different spectral response and can be biased to function as a photodiode, Comprising a carrier collection layer of a polar semiconductor material, characterized in that it is configured to collect photoexcited carriers of a first polarity when biased to function as a photodiode;
The isolation region is a semiconductor material between the first sensor group and the second sensor group, and the isolation region is a field that is doped and created between the first sensor group and the second sensor group. Characterized by being biased by separation,
Sensor group array.

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