JP2006120922A - Photoelectric conversion film laminated type color solid state imaging device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hybrid type photoelectric conversion film laminated type color solid state imaging device having a CCD type signal read-out circuit with good linearity of photoelectric conversion characteristics in a photoelectric conversion film. <P>SOLUTION: The hybrid type photoelectric conversion film laminated type color solid state imaging device includes a first photoelectric conversion element for photodetecting a first color incident light of the three primary colors to generate a signal charge, a second photoelectric conversion element for photodetecting a second color incident light to generate a signal charge, a third color signal charge storage part 131 for accumulating the signal charge according to the light amount of the third color incident light, a semiconductor substrate 120 in which a perpendicular transfer route 124 to which each signal potential is transmitted is formed, a photoelectric conversion film 140 which laminates on the semiconductor substrate 120 to photodetect the third color incident light to generate a signal charge, a vertical interconnection line 147 for connecting the pixel electrode layer 141 by which converting is performed to the photoelectric conversion film 140, and the third color signal charge storage part 131, and a potential barrier part 130 provided between the contact part 128 to the semiconductor substrate 120 of the vertical interconnection line 147, and the third color signal charge storage part 131. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention is a photoelectric conversion film in which incident light of one of the three primary colors is received by a photoelectric conversion film laminated on a semiconductor substrate and the remaining two colors of incident light transmitted through the photoelectric conversion film are formed on the semiconductor substrate. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photoelectric conversion film stacked color solid-state imaging device that receives light by an element, and in particular, it is easy to achieve a color balance between a color signal received by a photoelectric conversion film and a color signal received by a photoelectric conversion element The present invention relates to a photoelectric conversion film stacked color solid-state imaging device.

  In a single-plate color solid-state imaging device typified by a CCD type or CMOS type image sensor, three or four color filters are arranged in a mosaic pattern on an array of pixels for photoelectric conversion. Thereby, a color signal corresponding to the color filter is output from each pixel, and a color image is generated by performing signal processing on these color signals.

  However, in a color solid-state imaging device in which color filters are arranged in a mosaic shape, about 2/3 of incident light is absorbed by the color filter in the case of a primary color filter, the light use efficiency is low and the sensitivity is low. There's a problem. Further, since only one color signal can be obtained for each pixel, the resolution is poor, and in particular, there is a problem that false colors are conspicuous.

  Therefore, in order to overcome such a problem, an imaging apparatus having a structure in which a three-layer photoelectric conversion film is stacked on a semiconductor substrate on which a signal readout circuit is formed has been researched and developed (for example, the following patent document). 1, 2). In this imaging device, for example, pixels in which a photoelectric conversion film that generates signal charges (electrons, holes) with respect to blue (B), green (G), and red (R) light is sequentially stacked from a light incident surface. A readout unit having a structure and capable of independently reading out signal charges generated by light in each photoelectric conversion film is provided for each pixel.

  In the case of an imaging apparatus having such a structure, incident light is almost photoelectrically converted and read out, and the utilization efficiency of visible light is close to 100%, and color signals of three colors of R, G, and B are obtained in each pixel. Therefore, it is possible to generate a good image with high sensitivity and high resolution (false colors are not noticeable).

  In the imaging apparatus described in Patent Document 3 below, a triple well (photodiode) for detecting an optical signal is provided in a silicon substrate, and signals (surfaces) having different spectral sensitivities due to differences in the depth of the silicon substrate. To B (blue), G (green), and R (red) wavelengths. This utilizes the fact that the penetration distance of incident light into the silicon substrate depends on the wavelength. As with the imaging devices described in Patent Documents 1 and 2, this imaging device can also obtain a good image with high sensitivity and high resolution (false colors are not noticeable).

  However, the imaging devices described in Patent Documents 1 and 2 sequentially stack three layers of photoelectric conversion films on a semiconductor substrate, and the signal charges for R, G, and B generated in each photoelectric conversion film are obtained. Although it is necessary to form vertical wirings connected to the signal readout circuits formed on the respective semiconductor substrates, it is difficult to manufacture and there is a problem that costs increase due to low manufacturing yield.

  On the other hand, the imaging device described in Patent Document 3 has a structure in which blue light is detected by the shallowest photodiode, red light is detected by the deepest photodiode, and green light is detected by the intermediate photodiode. For example, in the shallowest photodiode, photoelectric charge is generated even by green light or red light, so that the spectral sensitivity characteristics of the R signal, G signal, and B signal are not sufficiently separated and the color reproducibility is poor. There is. In addition, in order to obtain a true R signal, G signal, and B signal, it is necessary to add / subtract the output signal from each photodiode, and the S / N of the image signal deteriorates due to this addition / subtraction process. .

  An image pickup apparatus described in Patent Document 4 has been proposed to improve each of the problems of the image pickup apparatuses described in Patent Documents 1, 2, and 3. This imaging device is a hybrid type of the imaging device described in Patent Literatures 1 and 2 and the imaging device described in Patent Literature 3, and the structure thereof is a semiconductor including only one layer of a photoelectric conversion film having sensitivity to green (G). The blue (B) and red (R) incident light that has been stacked on the substrate and transmitted through the photoelectric conversion film is received by a photodiode formed on the semiconductor substrate, as in a conventional image sensor. Yes.

  Since only one photoelectric conversion film is required, the manufacturing process is simplified, and cost increase and yield reduction can be avoided. In addition, since green light is absorbed by the photoelectric conversion film, the separation of spectral sensitivity characteristics of the blue and red photodiodes in the semiconductor substrate is improved, color reproducibility is improved, and S / N is also improved. There is an advantage that it is improved.

Special Table 2002-502120 JP 2002-83946 A JP-T-2002-513145 JP 2003-332551 A

  The hybrid type imaging device described in Patent Document 4 has advantages such as a reduction in manufacturing cost, an improvement in color reproducibility, and an improvement in S / N. However, the following another problem occurs. End up.

  The signal readout circuit provided on the semiconductor substrate of the hybrid type imaging device includes a CCD type signal readout circuit (charge transfer path and transfer electrode) and a CMOS type signal readout circuit (MOS transistor, signal wiring, etc.). However, here, the description is limited to a CCD signal readout circuit.

  When a CCD type signal readout circuit is applied to the image pickup apparatus described in Patent Document 4, signal charges from G pixels made of a photoelectric conversion film, and signal charges from B pixels and R pixels made of two layers of silicon photodiodes. Are first read and transferred to the vertical CCD register, then transferred to the horizontal CCD register and read from the output unit. This CCD type signal readout circuit has the advantages of high gain and good S / N. However, the CCD type signal readout circuit has the following four problems when applied to the above hybrid type imaging device. There is a need to resolve.

  (1) Regarding the G pixel of the photoelectric conversion film, there is a problem that the linearity of the photoelectric conversion characteristics is poor. The photoelectric conversion characteristics of the photoelectric conversion film vary greatly depending on the electric field in the film (or the voltage between terminals of the photoelectric conversion film). When light of the same light intensity is incident on the photoelectric conversion film, it is desirable that signal charges always accumulate at a constant rate. However, when the signal charge is accumulated in the photoelectric conversion film, the voltage between the terminals of the film is lowered, and the ratio of the accumulated charge amount is decreased. For this reason, the relationship between the light intensity and the output signal is shifted from the proportional relationship, and the linearity of the photoelectric conversion characteristics is deteriorated. Since such a problem does not occur in the B pixel and R pixel in silicon, it becomes difficult to balance the color of the G signal with respect to the B signal and the R signal, and the image quality is deteriorated.

  (2) The G pixel of the photoelectric conversion film has a problem that noise is large and an afterimage is conspicuous. Since a large amount of charges (carriers such as electrons) exist in the pixel electrode, vertical wiring, and the like, the signal charges generated by light cannot be read out to the vertical CCD in the complete transfer mode, resulting in an incomplete transfer mode. . In the incomplete transfer mode, a fixed charge always remains, so that kTC noise, noise due to fluctuations in the readout pulse, and the like are superimposed on the signal charge, and the S / N deteriorates. Furthermore, the afterimage is conspicuous because charge transfer in a state where the signal charge is small is very slow due to the thermal excitation effect.

  (3) There is a problem that an excessive signal charge discharging operation and an electronic shutter operation cannot be performed. This is because it is difficult to provide a vertical overflow drain for the photodiode that detects blue on the side close to the semiconductor substrate surface. This is because there is a photodiode for detecting red under the photodiode. Accordingly, it is not possible to discharge excessive charges generated by strong light or discharge unnecessary charges for electronic shutter operation.

  (4) There is a problem that the color separation of the blue signal and red signal detected by the two layers of photodiodes provided in the depth direction on the semiconductor substrate side is not sufficient. The light that has passed through the photoelectric conversion film becomes only R light and B light because G light is absorbed, and enters the two-layered photodiode. Since the absorption coefficient of the semiconductor with respect to B light is larger than the absorption coefficient of the semiconductor with respect to R light, the photodiode near the semiconductor substrate surface is relatively sensitive to B light, and the deep photodiode is relatively sensitive to R light. High sensitivity. Due to the absence of G light, the color separation of R and B is improved as compared with Patent Document 3, but the improvement of the color separation is not sufficient as long as the wavelength dependence of the absorption coefficient is utilized.

  A first object of the present invention is to provide a hybrid type photoelectric conversion film stacked color solid-state imaging device having a CCD type signal readout circuit with good linearity of photoelectric conversion characteristics in a photoelectric conversion film.

  A second object of the present invention is to provide a hybrid type photoelectric conversion film stacked color solid-state imaging device having a CCD type signal readout circuit in which S / N is good and an afterimage is not conspicuous.

  A third object of the present invention is a hybrid photoelectric conversion film laminated type having a CCD type signal readout circuit capable of discharging an excessive charge generated by strong light and discharging an unnecessary charge for an electronic shutter operation. The object is to provide a color solid-state imaging device.

  A fourth object of the present invention is to provide a hybrid type photoelectric conversion film laminated color solid-state image pickup having a CCD type signal readout circuit that improves color separation of red (R) and blue (B) and obtains good color reproducibility. To provide an apparatus.

  The photoelectric conversion film laminated color solid-state imaging device of the present invention receives a first photoelectric conversion element that receives first-color incident light of three primary colors and generates a signal charge, and receives second-color incident light to receive a signal charge. A semiconductor substrate on which a second photoelectric conversion element for generating light, a third color signal charge accumulating unit for accumulating signal charges corresponding to the amount of incident light of the third color, and a vertical transfer path for transferring the signal charges are formed. A photoelectric conversion film that is stacked on the semiconductor substrate and receives the third color incident light to generate a signal charge; a pixel electrode film deposited on the photoelectric conversion film; and the third color signal charge storage unit And a potential barrier portion provided between the contact portion of the vertical wire with the semiconductor substrate and the third color signal charge storage portion.

  With this configuration, even if signal charges are generated in the photoelectric conversion film and signal charges are stored in the third color signal charge storage part, the film potential of the photoelectric conversion film is constant because of the potential barrier part, and the photoelectric conversion film The linearity of the photoelectric conversion characteristics is maintained. For this reason, the color balance between the third color, the first color, and the second color is not lost, and the signal charge does not remain in the film, so that the influence of noise and the like can be avoided.

  The potential barrier portion and the third color signal charge storage portion of the photoelectric conversion film stacked color solid-state imaging device of the present invention are provided on the conductive first semiconductor layer and the first semiconductor layer. Three layers of a second semiconductor layer having a conductivity type opposite to the first semiconductor layer and a third semiconductor layer provided below the first semiconductor layer and having a conductivity type opposite to the first semiconductor layer A portion of the three-layer structure where the thickness or impurity density of the first semiconductor layer is small is used as the potential barrier portion and the first semiconductor layer of the three-layer structure is A portion where the thickness or impurity density is larger than the potential barrier portion is the third color signal charge storage portion.

  Even with this configuration, the photoelectric charge generated in the photoelectric conversion film by the incident light of the third color quickly moves to the third color signal charge storage unit and the film potential is kept constant, and the linearity of the photoelectric conversion characteristics is deteriorated. In addition, the influence of residual charges is avoided.

  The first photoelectric conversion element and the second photoelectric conversion element of the photoelectric conversion film stacked color solid-state imaging device of the present invention are provided by being stacked in the depth direction of the semiconductor substrate.

  With this configuration, it is possible to obtain signals of the three primary colors of the first color, the second color, and the third color with one light receiving unit, and it is possible to obtain a high-resolution image with high sensitivity and inconspicuous false colors. It becomes.

  In the photoelectric conversion film stacked color solid-state imaging device of the present invention, a first color signal charge accumulating unit for accumulating signal charges generated in the first photoelectric conversion element is connected to the first photoelectric conversion element and the second A second color signal charge accumulating unit for accumulating signal charges generated by the photoelectric conversion element is connected to the second photoelectric conversion element, and the first color signal charge accumulating unit, the second color signal charge accumulating unit, and the first color signal charge accumulating unit are connected. A vertical overflow drain is provided in each of the three-color signal charge storage units.

  With this configuration, the signal charge storage unit is provided separately from the photoelectric conversion element, and the signal charge is stored locally. This makes it easy to manufacture the overflow drain, facilitates unnecessary charge discharge, and can be equipped with an electronic shutter function. It becomes.

  The first photoelectric conversion element and the second photoelectric conversion element of the photoelectric conversion film stacked color solid-state imaging device of the present invention are arranged in a checkered pattern on the surface portion of the semiconductor substrate, and the top of the first photoelectric conversion element. Is stacked with a color filter that transmits the incident light of the first color and blocks the incident light of the second color, and transmits the incident light of the second color on the second photoelectric conversion element. A color filter for blocking incident light of the first color is laminated.

  With this configuration, the color separation performance of the first color and the second color is improved, and the color reproducibility of the image can be improved.

  In the photoelectric conversion film stacked color solid-state imaging device of the present invention, the third color signal charge storage unit, the first photoelectric conversion element, and the second photoelectric conversion element have a vertical overflow in the depth direction of the semiconductor substrate. A drain is provided.

  With this configuration, unnecessary charges can be easily discharged, and an electronic shutter function can be mounted.

  The photoelectric conversion film laminated color solid-state imaging device of the present invention has an opening for introducing incident light to the first photoelectric conversion element and the second photoelectric conversion element on the surface side of the semiconductor substrate. And the light shielding film which shields the light incidence to area | regions other than a 2nd photoelectric conversion element is provided, It is characterized by the above-mentioned.

  With this configuration, it is possible to avoid color mixing that occurs when light enters the third signal charge storage unit or the like.

  In the photoelectric conversion film stacked color solid-state imaging device of the present invention, the first color is blue, the second color is red, and the third color is green.

  With this configuration, it is possible to increase the number of green pixels that can be used as a luminance signal, and it is possible to obtain an image with high sensitivity and high resolution.

  According to the present invention, since the potential barrier portion that acts as a potential barrier with respect to the signal charge of the pixel formed of the photoelectric conversion film is provided, the terminal voltage of the photoelectric conversion film is kept constant regardless of the amount of accumulated signal charge. Therefore, the linearity of photoelectric conversion characteristics does not deteriorate, and the color balance is not lost. Also, color reproducibility can be improved by performing color separation using a color filter.

  Further, since the signal charge generated in the photoelectric conversion film immediately flows to the signal charge storage portion, there is no residual charge after reading, the S / N is good, and the afterimage becomes inconspicuous. In addition, since the overflow drain is provided, it is possible to discharge an excessive charge generated by strong light or discharge an unnecessary charge for an electronic shutter operation.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a schematic view of the surface of a photoelectric conversion film laminated color solid-state imaging device according to the first embodiment of the present invention. In the photoelectric conversion film stacked color solid-state imaging device 100, a large number of pixel cells 101 are arranged in a square lattice pattern in this example. A vertical transfer path (column direction CCD register) 102 arranged in the column direction is formed on the surface of the semiconductor substrate which is a lower layer portion of the basic cell 101 of the photoelectric conversion film stacked color solid-state imaging device 100. A horizontal transfer path (row direction CC register) 103 is formed on the lower side.

  An amplifier 104 is provided at the exit of the horizontal transfer path 103, and signal charges detected in each pixel cell 101 are first transferred to the horizontal transfer path 103 by the vertical transfer path 102, and then amplified by the horizontal transfer path 103. 104 and is output from the amplifier 104 as an output signal 105.

  On the surface of the semiconductor substrate, three-phase electrode terminals 111, 112, 113 connected to transfer electrodes (not shown) provided on the vertical transfer path 102 are provided, and OFD connected to an overflow drain described later. An electrode terminal 118 is provided, and two-phase electrode terminals 114 and 115 for transfer of the horizontal transfer path 103 are further provided.

  A photoelectric conversion film described later is stacked on the upper layer of the semiconductor substrate. This photoelectric conversion film is sandwiched between a pixel electrode film formed separately for each pixel and a counter electrode film (common electrode film) 116 formed in common to each pixel. An electrode terminal 117 for applying a predetermined bias voltage to the film 116 is provided.

  A rectangular frame 110 shown in FIG. 1 indicates a range indicating one basic cell in the present embodiment, and includes an area including one pixel cell 101 and a portion adjacent to the pixel cell 101 in the vertical transfer path 102. Is the basic cell 110.

  FIG. 2 is a schematic diagram showing the semiconductor substrate surface structure in the range of one basic cell 110. On the semiconductor substrate, a blue light receiving part (hereinafter also referred to as a B pixel) 134 and a red light receiving part (hereinafter also referred to as an R pixel) 135 are provided so as to overlap each other, as will be described later. An opening 139 of the light shielding film is provided so as to overlap above the portions 134 and 135 (light incident light direction: the front side in FIG. 2).

  The n-type semiconductor layers constituting the blue light receiving part 134 and the red light receiving part 135 are each slightly extended in the direction of the buried channel 124 constituting the vertical transfer path 102 shown in FIG. A charge storage unit 132 and a red signal charge storage unit 133 are provided.

A signal charge storage unit 131 for green is provided at a position adjacent to the light receiving units 134 and 135 in the direction along the vertical transfer path 102. The signal charge accumulating unit 131 is a part for accumulating photoelectric charges generated when light enters the photoelectric conversion film stacked on the semiconductor substrate. As will be described later, one end of the vertical wiring is connected to the pixel electrode film deposited on the photoelectric conversion film, and the other end of the vertical wiring is a contact in the n-type semiconductor region 129 formed on the semiconductor substrate. N ⁺ connected to the semiconductor region 128. The n-type semiconductor region 129 and the signal charge storage portion 131 are connected by an n-type semiconductor layer, and a potential barrier portion 130 is provided at the connection portion.

  Transfer electrodes 121, 122, 123 corresponding to the signal charge storage units 131, 132, 133 are provided on the embedded channel 124, and each transfer electrode 121, 122, 123 also serves as a read electrode, so The portion extends to the end position of each signal charge storage portion 131, 132, 133.

  FIG. 3 is a schematic cross-sectional view of the photoelectric conversion film stacked color solid-state imaging device at the position of the line III-III in FIG. 2, and shows the signal charge storage unit 131 for green, the potential barrier unit 130, etc. provided on the semiconductor substrate. In addition, a cross section of a photoelectric conversion film or the like provided on the upper layer is shown. Similarly, FIG. 4 is a schematic cross-sectional view of the photoelectric conversion film stacked color solid-state imaging device at the position of the IV-IV line in FIG. 2. In addition to the photoelectric conversion film, a blue signal charge storage unit 132 and a light receiving unit 134 are used. , 135 and the like. Similarly, FIG. 5 is a schematic cross-sectional view of the photoelectric conversion film stacked color solid-state imaging device at the position of the VV line in FIG. 2. In addition to the photoelectric conversion film, the signal charge storage unit 133 and the light receiving unit 134 for red are used. , 135 and the like.

  A p-well layer 138 is formed on the surface portion of the n-type semiconductor substrate 120, and a thin or low impurity density n-type semiconductor layer 135 (FIG. 5) is formed deep in the p-well layer 138. An n-type semiconductor layer 133 that reaches the surface of the semiconductor substrate is connected to the n-type semiconductor layer 135. The n-type semiconductor layer 133 is preferably formed to have a large thickness and an impurity density higher than that of the n-type semiconductor layer 135.

  A pn junction formed between the n-type semiconductor layer 135 and the upper and lower p-well layers 138 forms a red light photodiode. Since this photodiode is deep in the semiconductor substrate, it is highly sensitive to long-wavelength (red) light, and signal charge is generated mainly according to the amount of received red light. This signal charge is the signal charge. Accumulated in the accumulation unit (n-type semiconductor layer) 133.

  The p well layer 138 is formed thin in the signal charge storage portion 133, and this thin portion 138r functions as a potential barrier for the red (R) pixel of the overflow drain.

  An n-type semiconductor layer 134 that is separated from the n-type semiconductor layer 135 is formed in a shallow portion of the p-well layer 138 that overlaps the n-type semiconductor layer 135. The n-type semiconductor layer 134 is formed thin or has a low impurity density, and an n-type semiconductor layer 132 having a thick layer is formed at the end thereof. The n-type semiconductor layer 132 is preferably formed to have a higher impurity density than the n-type semiconductor layer 134.

  A pn junction formed between the n-type semiconductor layer 134 and the p-well layer 138 below it forms a blue light photodiode. Since this photodiode is located in the shallow part of the semiconductor substrate, it has high sensitivity to short wavelength (blue) light, and signal charges are generated mainly according to the amount of received blue light. The signal charge is stored in the signal charge storage portion (n-type semiconductor layer) 132.

  The p well layer 138 is thinly formed in the signal charge storage portion 132, and the thin portion 138b functions as a potential barrier for the blue (B) pixel of the overflow drain.

A p ⁺ layer 150 is formed in an appropriate region of the outermost surface portion of the semiconductor substrate, and a gate insulating film 146 is formed over the entire surface.

  In FIG. 3, the signal charge storage unit 131 for green is composed of an n-type semiconductor layer 131 formed in a p-well layer 138. The n-type semiconductor layer 131 is formed with a thick layer or a high impurity density so that a deep potential well is formed.

  The p-well layer 138 is thinly formed in the signal charge storage portion 131, and this thin portion 138g functions as a potential barrier for the green (G) pixel of the overflow drain.

An n-type semiconductor layer 130 that is thin or has a low impurity density is connected to the end of the signal charge storage portion 131, and the surface portion of the n-type semiconductor layer 130 and most of the surface portion of the n-type semiconductor layer 131 are p. ^The n-type semiconductor layer 130 is covered with the ⁺ layer 150 and functions as a potential barrier portion.

An n-type semiconductor layer 129 whose surface is not covered with the p ⁺ layer 150 is connected to the end of the n-type semiconductor layer 130, and an n ⁺ region 128 is formed in the n-type semiconductor layer 129. A vertical wiring 147 is connected to the n ⁺ region 128 through the gate insulating film 146.

  On the buried channel (n-type semiconductor layer) 124 constituting the vertical transfer path formed in the p-well layer 138, the transfer electrodes 121 (FIG. 3), 122 (FIG. 4), 123 (FIG. 5) is provided. Each transfer electrode 121, 122, 123 is formed so that the end thereof extends to the end position of the signal charge storage portion 131, 132, 133.

  A transparent insulating film 144 is formed on the gate insulating film 146 and the transfer electrodes 121, 122, and 123, and a light shielding film 145 is formed in the insulating film 144. The light shielding film 145 is provided with an opening 137 (FIG. 3) through which the vertical wiring 147 passes without contact, and an opening 139 (FIGS. 2, 4 and 4) for allowing light to enter each light receiving portion (the photodiode described above). FIG. 5) is provided.

  A transparent insulating film 143 is laminated on the transparent insulating film 144, and an appropriate aluminum wiring is formed between the insulating films 144 and 143, and the opening is positioned at a position matching the opening 137. An opaque metal film 148 slightly wider than 137 is formed. This prevents incident light from reaching the semiconductor substrate through the opening 137 and avoids color mixing.

A pixel electrode film 141 divided for each pixel is formed on the transparent insulating film 143, a photoelectric conversion film 140 is formed on each pixel electrode film 141, and a counter electrode film 116 is formed thereon. The transparent protective film 142 is formed thereon. The vertical wiring that connects the pixel electrode film 141 and the contact n ⁺ region 128 is a first vertical wiring such as tungsten W or copper Cu embedded in the transparent insulating film 144 that connects the n ⁺ region 128 and the metal film 148. A wiring (plug) 147 and a second vertical wiring (plug) 149 such as tungsten W or copper Cu embedded in a transparent insulating film 143 connecting the metal film 148 and the pixel electrode film 141 are formed.

  The pixel electrode film 141 and the counter electrode film 116 are formed of a material that is optically transparent or has little light absorption. For example, it is formed of a metal compound such as ITO or a very thin metal film.

  The photoelectric conversion film 140 is mainly sensitive to light in the green (G) wavelength region, and generates photoelectric charges according to the amount of incident green light in the incident light. The structure of the photoelectric conversion film 140 may be a single layer film structure or a multilayer film structure, and is mainly composed of inorganic materials (silicon, compound semiconductors, nanoparticles thereof, etc.) sensitive to green, organic semiconductor materials, and organic dyes. It is formed of a material or an inorganic material.

  In the basic cell, the center of the G pixel, that is, the center of the pixel electrode film 141, the center of the B pixel, that is, the center of the n-type semiconductor layer 134, the center of the R pixel, that is, the center of the n-type semiconductor layer 135, and the opening 139. It is desirable to manufacture so that the centers of these coincide with each other when viewed from the vertical direction (light incident direction) of the semiconductor substrate 120.

A portion in the semiconductor substrate composed of the n ⁺ type semiconductor region 128 for contact, the potential barrier portion 130, and the charge storage portion 131 is collectively referred to as a “reading portion”. It is preferably provided at a position deviated from the vertical direction (column direction) from the vertical direction and substantially at a position covered by the light shielding film 145 at an intermediate position between two openings 139 adjacent in the column direction.

  Furthermore, in the present embodiment, the counter electrode film 116 is a single-layer film electrode. However, like the pixel electrode film 141, the counter electrode film 116 is divided into rectangular electrode films, and each electrode film is commonly wired. It is good also as a structure.

When light from a subject enters the photoelectric conversion film stacked color solid-state imaging device according to the present embodiment configured as described above, first, green light of incident light is absorbed by the photoelectric conversion film 140, A signal charge is generated. This signal charge flows to the contact n ⁺ region 128 through the vertical wirings 149 and 147, and is accumulated in the signal charge accumulation unit 131 through the potential barrier unit 130.

  Of the incident light, blue light and red light pass through the photoelectric conversion film 140 and reach the semiconductor substrate through the opening 139. Blue light having a short wavelength is absorbed by the surface portion of the semiconductor substrate, and signal charges are generated by the photodiode provided in this portion. This signal charge is stored in the signal charge storage unit 132.

  The red light reaches the deep part of the semiconductor substrate, and signal charges are generated by the photodiode provided in the deep part. This signal charge is stored in the signal charge storage unit 133.

  When the readout potential is applied to the transfer electrodes 121, 122, 123, the signal charges accumulated in the signal charge accumulation units 131, 132, 133 are read out to the buried channel 124 of the vertical transfer path and transferred to the transfer electrodes. By applying the potential, the voltage is transferred along the vertical transfer path to the horizontal transfer path 103 in FIG. The vertical transfer path (column direction CCD) is a three-phase drive CCD in this embodiment, and the signal charges of the entire screen can be read out by three-field reading.

  In the photoelectric conversion film stacked color solid-state imaging device according to the present embodiment, the potential barrier unit 130 is provided in the middle of flowing and storing the signal charge generated in the photoelectric conversion film 140 to the signal charge storage unit 131. Therefore, the film potential of the photoelectric conversion film 140 (the potential of the pixel electrode film 141) does not change as charges are accumulated as in the conventional case, and the film potential is almost equal to the potential barrier portion regardless of the amount of charges accumulated. The voltage V1 is fixed.

  Therefore, in the photoelectric conversion film stacked color solid-state imaging device according to the present embodiment, assuming that the voltage between the film terminals at which good photoelectric conversion characteristics can be obtained with the photoelectric conversion film 140 is V2, the voltage of (V1 + V2) is the common electrode film. 116, good photoelectric conversion is always performed in the photoelectric conversion film 140 regardless of the amount of charge accumulated in the signal charge accumulation unit 131, and the light incident intensity on the photoelectric conversion film 140 and the photoelectric conversion film 140 The linearity between the output signal strengths of the two is improved. Thereby, the color balance between the red signal and blue signal detected by the R pixel and B pixel provided on the semiconductor substrate 120 side and the green signal detected by the photoelectric conversion film 140 is not lost, and a good image is obtained. Is possible.

  Further, in the photoelectric conversion film stacked color solid-state imaging device of the present embodiment, since the vertical overflow drain is provided, excess charges generated by strong light are transferred from the signal charge storage units 131, 132, 133 to the substrate 120 side. It is possible to discharge unnecessary charges to the substrate 120 side for the discharging operation and the electronic shutter operation. If the voltage of the overflow drain is adjusted so that the potential barrier becomes approximately V1 or more, the voltage of the pixel electrode film 141 is maintained at the voltage V1 even for excessive light.

  In the present embodiment, the size of the potential wells of the signal charge accumulating units 131, 132, and 133 is designed so that reading of the signal charges in the column direction CCD is in the complete transfer mode. That is, when reading out signal charges to the column direction CCD, the layer thickness and impurity density of the semiconductor layer related to the signal charge storage unit are selected so that no fixed residual charge remains in the signal charge storage unit.

  Therefore, in the present embodiment, kTC noise caused by incomplete charge transfer, noise due to voltage fluctuation of the readout pulse, and low signal level afterimage are eliminated. In addition, since the signal charge storage units 131, 132, and 133 are provided at locations where light shielding is performed by the light shielding film 145 and the metal film 148, light is incident on the signal charge storage units 131, 132, and 133. It is possible to avoid color mixing and obtain a high-quality image signal.

(Second Embodiment)
FIG. 6 is a schematic view of the surface of a photoelectric conversion film laminated color solid-state imaging device according to the second embodiment of the present invention. In the first embodiment described above, a two-layer pn junction photodiode is formed in a semiconductor substrate, and an overflow drain is further provided. This is because the manufacturing conditions for forming the two-layer pn junction photodiode are difficult, and a decrease in manufacturing yield is unavoidable, which may increase the manufacturing cost. In addition, since the color separation of blue and red is performed with a two-layer pn junction photodiode utilizing the wavelength dependence of the light absorption coefficient, there is a limit to blue and red color separation, and high-precision color reproducibility There is a problem that is difficult. An embodiment which solves these problems is the second embodiment.

  In the photoelectric conversion film stacked color solid-state imaging device 200 according to the present embodiment shown in FIG. 6, a light receiving portion 201b for B pixels and a light receiving portion 201r for R pixels are formed on a semiconductor substrate, and the upper layer of the semiconductor substrate. However, in this embodiment, the light receiving portions 201b and 201r are stacked in the depth direction of the semiconductor substrate in the same manner as in the first embodiment. Instead, the difference is that the checkerboard is arranged on the surface layer of the semiconductor substrate.

  In addition, the G signal charge accumulating portion 201g for accumulating signal charges corresponding to the incident light quantity of green light generated for each G pixel in the photoelectric conversion film is formed on the semiconductor substrate as in the first embodiment. In the embodiment, the B pixel light receiving portions 201b and the R pixel light receiving portions 201r are alternately arranged in one row, and the next lower R pixel light receiving portions 201r and B pixel light receiving portions 201b are alternately arranged in one row. The G signal charge accumulating unit 201g is provided between the rows and at a position shifted by 1/2 pitch from the B pixel light receiving unit 201b and the R pixel light receiving unit 201r. That is, the B pixel light receiving part 201b, the R pixel light receiving part 201r, and the G signal charge accumulating part 201g are arranged in a so-called honeycomb on the semiconductor substrate.

  The vertical transfer path 203 is formed up to the horizontal transfer path 204 meandering in the vertical direction (column direction) so as to avoid the B pixel light receiving section 201b, the R pixel light receiving section 201r, and the G signal charge storage section 201g. The vertical transfer path 203 includes a buried channel 240 (FIGS. 8 and 9) to be described later, first to fourth phase transfer electrodes 207 to 210 and transfer electrodes 212 and 213 of the column direction CCD. The first to fourth phase electrode terminals 214 to 217 of the column direction CCD are connected to the transfer electrodes 207 to 213, and the first phase and second phase electrode terminals 218 and 219 are connected to the horizontal transfer path 204. .

  An output amplifier 205 is formed at the exit of the horizontal transfer path 204, an overflow drain electrode terminal 222 is provided on the semiconductor substrate, and a common electrode film (counter electrode film) 220 is deposited on the entire surface of the photoelectric conversion film. Is connected to an electrode terminal 221 for applying a predetermined bias potential to the common electrode film 220.

  The B signal charge, R signal charge, and G signal charge that are generated and accumulated when light from the subject is incident are read out to the vertical transfer path 203 in the direction of the arrow 211 (showing the readout gate) in the figure, respectively. Then, the vertical transfer path 203 is transferred to the horizontal transfer path 204, then transferred through the horizontal transfer path 204, and finally amplified by the amplifier 205, and then output from the photoelectric conversion film stacked color solid-state imaging device 200 as an output signal 206. Is done.

  FIG. 7 is an enlarged schematic view of the main part of the surface of the photoelectric conversion film stacked color solid-state imaging device shown in FIG. The pixel electrode film 223 deposited on the photoelectric conversion film and divided for each G pixel is above the R pixel light receiving part 201r or the B pixel light receiving part 201b on the upper right side in FIG. ) And provided in a wide range including the surrounding transfer electrodes with the R pixel and the B pixel as the center, and the lower left corner of the pixel electrode film 223 extends to the position of the G signal charge storage portion 201g and is connected to the extension portion. The vertical wiring is connected to a contact portion 225 provided in the G signal charge storage portion 201g. That is, in the present embodiment, the G signal charge storage portion 201g is provided at an intermediate position between the four adjacent pixel electrode films 223.

  A color filter 224b that transmits blue light and blocks red light is provided over the pixel electrode film 223 above the B pixel light receiving portion 201b (front side of the paper surface), and above the R pixel light receiving portion 201r (on the paper surface). A color filter 224r that transmits red light and blocks blue light is provided over the pixel electrode film 223 on the front side. In a region other than where the color filters 224r and 224b are provided, a light shielding film for preventing incident light from reaching the semiconductor substrate is provided.

  FIG. 8 is a schematic cross-sectional view of the photoelectric conversion film stacked color solid-state imaging device at the position of the G signal charge storage unit 201g (the position of the line VIII-VIII in FIG. 7). FIG. FIG. 8 is a schematic cross-sectional view of a photoelectric conversion film stacked color solid-state imaging device at a position IX-IX in FIG. 7.

  In FIG. 8, a p-well layer 231 is provided on the surface portion of an n-type semiconductor substrate 230, and on the surface portion of the p-well layer 231, an n-type semiconductor layer 201g having a thick layer or a high impurity density is provided. An n-type semiconductor layer 239 which is continuously provided and has a thin layer thickness or a low impurity density, and an n-type semiconductor layer 240 as a buried channel which is separated from these and constitutes a vertical transfer path are provided. The n-type semiconductor layer 201g functions as a G signal charge storage portion illustrated in FIG. 7, and the n-type semiconductor layer 239 functions as a potential barrier portion.

A p ⁺ -type semiconductor layer 243 is provided on most of the surface of the n-type semiconductor layer 201g and a part of the surface of the n-type semiconductor layer 239 continuous thereto, and a p-well layer 231g below the n-type semiconductor layer 201g. The layer thickness is reduced to function as a potential barrier for the overflow drain. An n ⁺ type semiconductor region 225 for contact (see FIGS. 7 and 8) is provided on a surface portion of the n type semiconductor layer 239 where the p ⁺ type semiconductor layer 243 is not formed.

The uppermost surface of the p-well layer 231 is covered with a gate insulating film 232, and a transfer electrode serving as a readout electrode is extended on the gate insulating film 232 at a position covering the buried channel 240 to the end position of the n-type semiconductor layer 201g. 209 is formed. A transparent insulating film 233 is laminated on the gate insulating film 232 and the transfer electrode 209, and a first vertical wiring (tungsten) that penetrates the insulating film 233 and the gate insulating film 232 and is connected to the n ⁺ type semiconductor region 225. 235 is buried. In addition, a light shielding film 234 that blocks incident light from reaching the surface of the semiconductor substrate is embedded in the insulating film 233. The light shielding film 234 is provided with an opening 241 through which the first vertical wiring 235 penetrates in a non-contact manner.

  A transparent insulating film 228 is laminated on the transparent insulating film 233, but light does not enter the semiconductor substrate side from the opening 241 on the opening 241 of the light shielding film 234 therebetween. An opaque metal film 236 having a larger area than the opening 241 is inserted. The end portion of the first vertical wiring 235 is in electrical contact with the metal film 236. In addition, a second vertical wiring (tungsten W plug or the like) 237 whose one end is in contact with the metal film 236 is embedded in the insulating film 228, and the other end of the second vertical wiring 237 is exposed at the end face of the insulating film 228. .

  A pixel electrode film 223 divided for each G pixel is provided on the insulating film 228, and a portion of the pixel electrode film 223 extending up to a position above the G signal charge storage portion 201 g is the second vertical wiring 237. It is electrically connected to the end face.

  On the insulating film 228 and the pixel electrode film 223, a photoelectric conversion film 226 that receives green light and generates photocharges is stacked using a film forming technique or the like, and a common electrode film 220 is deposited thereon. A transparent protective film 227 is laminated thereon.

In FIG. 9, an n-type semiconductor layer (light receiving portion for B pixel) 201 b and a buried channel (n-type semiconductor layer) 240 constituting a vertical transfer path are formed on the surface portion of the p-well layer 231 of the n-type semiconductor substrate 230. And a p ⁺ type semiconductor layer 244 is formed on most of the surface portion of the n type semiconductor layer 201b.

  A pn junction formed between the n-type semiconductor layer 201b and the p-well layer 231 below forms a photodiode that receives blue light and performs photoelectric conversion. The p-well layer 231b below the n-type semiconductor layer 201b has a small thickness and functions as a potential barrier for the overflow drain.

  The uppermost surface of the p-well layer 231 is covered with a gate insulating film 232, and a transfer electrode serving as a readout electrode that extends to the end position of the n-type semiconductor layer 201b on the gate insulating film 232 at a position covering the buried channel 240. 207 is formed.

  A transparent insulating film 233 is laminated on the gate insulating film 232 and the transfer electrode 207, and a light shielding film 234 for blocking incident light from reaching the surface of the semiconductor substrate is embedded in the insulating film 233. The light shielding film 234 is provided with an opening 229 for introducing light into the B pixel light receiving portion (n-type semiconductor layer) 201b.

  A color filter 224b that transmits blue light and blocks red light is stacked on the transparent insulating film 233, and a pixel electrode film 223 for G pixel is stacked thereon, and a photoelectric conversion film 226 is stacked thereon. Are stacked, a common electrode film 220 is stacked thereon, and a transparent protective film 227 is stacked thereon.

  In the present embodiment, the center position of the pixel electrode film 223 constituting the G pixel, the center position of the B pixel (or R pixel), and the center position of the opening 229 are manufactured so as to substantially coincide with the light incident direction. .

  In addition, as the materials for the photoelectric conversion film 226 and the electrode film described above, the same materials as those in the first embodiment described above are used. Although the schematic cross-sectional view of the R pixel is omitted, in the R pixel, a color filter 224r (see FIG. 7) that transmits red light and blocks blue light is used instead of the color filter 224b in FIG. Only the point is different from the structure of the B pixel.

  When light from a subject enters the photoelectric conversion film stacked color solid-state imaging device 200 according to the present embodiment, green light in the incident light is photoelectrically converted by the photoelectric conversion film 226, and signal charges are vertically transferred from the pixel electrode film 223. The wiring 237, 235, the contact part 225, the n-type semiconductor layer (potential barrier part) 239, and the n-type semiconductor layer 201g flow, and the signal charge for green is accumulated in the n-type semiconductor layer 201g.

  Of the incident light, red light and blue light pass through the photoelectric conversion film 226, but are shielded except for the openings 229 of the light shielding film 234 and do not reach the surface of the semiconductor substrate. Since a color filter that blocks blue light is provided on the light passing through the opening 229 of the R pixel light receiving unit 201r, only the red light component is incident on the R pixel light receiving unit (n-type semiconductor layer) 201r. Photo charge is generated. A signal charge corresponding to the amount of received red light is accumulated in the n-type semiconductor layer 201r.

  The light passing through the aperture 229 of the B pixel light receiving unit 201b is provided with a color filter that blocks red light, so that only the blue light component is incident on the B pixel light receiving unit (n-type semiconductor layer) 201b. Photo charge is generated. A signal charge corresponding to the amount of received blue light is accumulated in the n-type semiconductor layer 201b.

  Thereafter, a read pulse (high positive voltage pulse) is applied to the transfer electrode serving as the read electrode of the vertical transfer path (column direction CCD), the signal charge of each pixel is read to the vertical transfer path, and the transfer pulse is transferred to the transfer electrode. Is applied, the signal charge is transferred along the vertical transfer path, and is transferred along the horizontal transfer path to be output as an image signal from the solid-state imaging device 200.

  Also in this embodiment, since the signal charge generated in the photoelectric conversion film 226 passes through the potential barrier section 239 and is stored in the signal charge storage section (n-type semiconductor layer) 201g, the film potential of the photoelectric conversion film 226, that is, G The potential of the pixel electrode film 223 of the pixel is held at the potential of the potential barrier portion 239. As a result, the membrane potential does not decrease as the signal charge is accumulated, the linearity of the photoelectric conversion characteristics is maintained, and the color balance with the red signal and the blue signal is not lost.

  In the present embodiment, only the red light after the blue light is blocked by the color filter 224r is incident on the R pixel light receiving portion 201r, and only the blue light after the red light is blocked by the color filter 224b is B. Since the light is incident on the pixel light receiving portion 201b, the color separation performance is high, and thus the color reproducibility is improved.

  Further, in the present embodiment, similar to the first embodiment, advantages such as noise and electronic shutter can be obtained, and the R pixel light receiving portion and the B pixel light receiving portion provided on the semiconductor substrate are arranged in the depth direction. Therefore, the manufacturing yield is improved and the manufacturing cost is reduced as compared with the first embodiment.

  In the present embodiment, the vertical transfer path (column direction CCD) is a four-phase drive CCD, but it goes without saying that another type of CCD such as a six-phase drive may be used. In addition, in order to increase the light collection efficiency, a microlens may be provided on the opening 229, which increases the sensitivity (particularly the B pixel and the R pixel).

  Furthermore, in this embodiment, the optical color filter is provided between the pixel electrode film and the semiconductor substrate, but may be provided on the upper surface of the common electrode film. In this case, since green (G) light needs to reach the photoelectric conversion film 226, an optical filter that transmits blue (B) light and green (G) light is provided for the R pixel. Provides a filter that transmits red (R) light and green (G) light.

  Furthermore, in this embodiment, the number of G signals is twice the number of R signals and the number of B signals. This method makes it possible to obtain a high-resolution image, but the signal processing becomes complicated. Therefore, a pixel electrode film at the position of the adjacent B pixel and R pixel may be wired in common, and a G pixel signal may be added and read by two pixels. As a result, the R, G, and B signals are the same in number, and signal processing is simplified.

  Furthermore, in this embodiment, the R, G, and B pixels are arranged so that the center of the G pixel electrode film and the center of the opening 229 coincide with each other. However, the center position of the G pixel electrode film is an intermediate position between adjacent openings 229. By shifting the G pixel from the R pixel and the B pixel, the number of sample points increases, and a high-resolution image can be obtained.

  As described above, according to each of the above embodiments, in the G pixel composed of the photoelectric conversion film 226 sandwiched between the pixel electrode and the counter electrode, the pixel electrode side has a potential barrier against the signal charge. Since a potential barrier section that behaves and a signal charge storage section that stores light-generated signal charges are provided, a constant terminal voltage (a constant average electric field inside the film) is applied to the photoelectric conversion film regardless of the amount of signal charges accumulated. The signal charge generated in the photoelectric conversion film is quickly moved from the film to the G signal charge accumulation portion. Therefore, the deterioration of the linearity of the photoelectric conversion characteristics is eliminated. Furthermore, since the size of the potential well of the G signal charge storage unit is selected so that the signal charge can be completely transferred, kTC noise, noise due to fluctuations in the readout pulse, and the like are not superimposed on the signal charge. Even afterimages with low signal levels become inconspicuous.

  Further, when a B pixel and an R pixel having a two-layer structure are formed in a semiconductor substrate, a B signal charge accumulation portion and an R signal charge accumulation portion, which are deep potential wells, are provided at positions close to the readout gates provided respectively, and By providing a vertical overflow drain under the R, G, and B signal charge storage portions (in the depth direction of the semiconductor substrate), the signal charge of each pixel is stored in the R, G, and B signal charge storage portions. The signal charge of each pixel can be discharged by the vertical overflow drain. Accordingly, it is possible to discharge an excessive charge generated by strong light or discharge an unnecessary charge for an electronic shutter operation.

  Further, a B pixel and an R pixel are formed in a semiconductor substrate with a single layer photodiode structure (same as a conventional photodiode with an overflow drain), and a G signal charge storage portion is provided in the same layer and below (semiconductor substrate). By providing a vertical overflow drain also in the depth direction), it is possible to discharge excess charges generated by strong light or discharge unnecessary charges for electronic shutter operation. In this case, R and B color separation is improved and color reproduction is performed by arranging optical filters having different characteristics on the incident optical path so that the spectral sensitivity characteristics of the B pixel and the R pixel become desired characteristics, respectively. Good.

  The photoelectric conversion film laminated color solid-state imaging device according to the present invention is useful as a color solid-state imaging device that replaces a conventional CCD type or CMOS type image sensor because it is easy to manufacture and has a high manufacturing yield.

It is a surface schematic diagram of the photoelectric conversion film lamination type color solid-state imaging device concerning a 1st embodiment of the present invention. It is a schematic diagram which shows the semiconductor substrate surface structure of the range of the basic cell 110 part shown in FIG. FIG. 3 is a schematic sectional view taken along line III-III in FIG. 2. FIG. 4 is a schematic cross-sectional view taken along line IV-IV in FIG. 2. FIG. 5 is a schematic cross-sectional view taken along line VV in FIG. 2. It is a surface schematic diagram of the photoelectric conversion film laminated | stacked color solid-state imaging device which concerns on the 2nd Embodiment of this invention. FIG. 7 is an enlarged schematic view of the main part of the surface of the photoelectric conversion film stacked color solid-state imaging device shown in FIG. 6. FIG. 8 is a schematic cross-sectional view taken along line VIII-VIII in FIG. 7. FIG. 8 is a schematic cross-sectional view taken along line IX-IX in FIG. 7.

Explanation of symbols

100, 200 Photoelectric conversion film stacked color solid-state imaging device 101 Light receiving unit 102, 203 Vertical transfer path (column CCD)
103,204 Horizontal transfer path (row direction CCD)
110 Basic cells 116, 220 Common electrode film (counter electrode film)
118, 222 Overflow drain (OFD) electrode terminal 120 n-type semiconductor substrate 121, 122, 123 Transfer electrode 124 Embedded channel 125, 126, 127 in vertical transfer path Read gate 128 Contact n ⁺ region 130, 239 Potential barrier 131, 201 g G signal charge storage section 132 B signal charge storage section 133 R signal charge storage section 134 B pixel light receiving section (n-type semiconductor layer)
135 R pixel light receiving part (n-type semiconductor layer)
138 P well layers 137, 139, 229, 241 Openings 140 Photoelectric conversion films 141, 223 G pixel pixel electrode films 145, 234 Light shielding films 147, 149, Vertical wirings 148, 236 Opaque electrode film 201r R having a light shielding function Pixel light receiving portion 201b B pixel light receiving portions 224r, 224b Color filter 225 Contact n ⁺ regions 138r, 138g, 138b, 231g, 231b Vertical overflow drain potential barrier

Claims (8)

  The first photoelectric conversion element that receives the first color incident light of the three primary colors and generates a signal charge, the second photoelectric conversion element that receives the second color incident light and generates the signal charge, and the third color incident light. A semiconductor substrate on which a third color signal charge accumulating unit for accumulating signal charges according to the amount of light and a vertical transfer path for transferring each signal charge are formed, and the third color incident is laminated on the semiconductor substrate. A photoelectric conversion film that receives light to generate a signal charge; a vertical wiring that connects the pixel electrode film deposited on the photoelectric conversion film and the third color signal charge storage unit; and the semiconductor of the vertical wiring A photoelectric conversion film stacked color solid-state imaging device, comprising: a potential barrier portion provided between a contact portion to a substrate and the third color signal charge storage portion.   The potential barrier section and the third color signal charge storage section are provided with a first semiconductor layer having a conductivity type, and a second semiconductor layer having a conductivity type opposite to the first semiconductor layer, provided on the upper side of the first semiconductor layer. A three-layer structure of a first semiconductor layer and a third semiconductor layer having a conductivity type opposite to that of the first semiconductor layer, wherein the first of the three-layer structures is provided. A portion where the thickness or impurity density of one semiconductor layer is small is used as the potential barrier portion, and the thickness or impurity density of the first semiconductor layer of the three-layer structure is formed larger than the potential barrier portion. 2. The photoelectric conversion film laminated color solid-state imaging device according to claim 1, wherein the third color signal charge storage unit is used as the third color signal charge storage unit.   3. The photoelectric conversion film stacked type according to claim 1, wherein the first photoelectric conversion element and the second photoelectric conversion element are stacked in the depth direction of the semiconductor substrate. Color solid-state imaging device.   A first color signal charge accumulating unit for accumulating signal charges generated by the first photoelectric conversion element is connected to the first photoelectric conversion element, and a second color for accumulating signal charges generated by the second photoelectric conversion element. A signal charge storage unit is connected to the second photoelectric conversion element, and a vertical overflow drain is provided in each of the first color signal charge storage unit, the second color signal charge storage unit, and the third color signal charge storage unit. The photoelectric conversion film laminated color solid-state imaging device according to claim 3, wherein the photoelectric conversion film stacking type color solid-state imaging device is provided.   The first photoelectric conversion element and the second photoelectric conversion element are arranged in a checkered pattern on the surface portion of the semiconductor substrate, and transmit incident light of the first color on the first photoelectric conversion element. A color filter that blocks the incident light of the second color is laminated, and a color filter that transmits the incident light of the second color and blocks the incident light of the first color is stacked on the second photoelectric conversion element. The photoelectric conversion film stacked color solid-state imaging device according to claim 1, wherein the photoelectric conversion film stacked color solid-state imaging device is stacked.   6. The vertical overflow drain is provided in the depth direction of the semiconductor substrate in the third color signal charge storage unit, the first photoelectric conversion element, and the second photoelectric conversion element. 2. A photoelectric conversion film laminated color solid-state imaging device according to 1.   An opening for introducing incident light into the first photoelectric conversion element and the second photoelectric conversion element is provided on the surface side of the semiconductor substrate so that light is incident on a region other than the first photoelectric conversion element and the second photoelectric conversion element. 7. The photoelectric conversion film laminated color solid-state imaging device according to claim 1, further comprising a light shielding film for shielding.   8. The photoelectric conversion film stacked color according to claim 1, wherein the first color is blue, the second color is red, and the third color is green. 9. Solid-state imaging device.

Images