JP4661207B2 - Infrared sensor manufacturing method - Google Patents

Description

The present invention relates to a method for manufacturing an infrared sensor.

In the conventional infrared sensor described in the following Patent Document 1, in order to increase the thermal resistance of the support beam, the sensitivity of the infrared sensor is increased by forming a thin silicon oxide film constituting the support beam. The manufacturing method is a method of thinning the support beam by stacking a high etching sacrificial layer only on the support beam portion.
When patterning when forming the slit for heat separation, the sensor region and the wiring region are formed flat, and the height of both is the same, so that the heat of the infrared absorbing film and its supporting beam Increase the processing accuracy of the slit for separation, and make the slit as narrow as possible. As a result, the area of the infrared absorption film is increased, and the sensitivity of the infrared sensor is increased.
The structure of the thermopile infrared sensor and the detection principle are described in the following Patent Document 2 and Non-Patent Document 1.

JP 2001-281655 A Japanese Patent Laid-Open No. 11-258039 “48 × 32 element thermoelectric infrared focal plane array with precisely patterned Au Black absorber” M. Hirota et al. Sensors and Materials, vol. 12, No. 5 (2000) 289-300

Usually, as the number of wiring layers increases from two to three, the height of the wiring region in which the MOSFET and the capacitor are formed increases. In the above conventional example, it is necessary to make the thickness of the infrared absorption film equal to the thickness of the wiring region, so that the heat capacity of the infrared absorption film increases, resulting in a large thermal time constant and a slow response speed. There was a problem that. In order to reduce the thermal time constant and increase the response speed, it is necessary to reduce the thickness of the infrared absorption film.
The problems to be solved by the present invention are: (1) widening the area of the infrared absorbing film by narrowing the slit for heat separation, increasing the sensitivity of the infrared sensor, and (2) reducing the thermal time constant. It is another object of the present invention to provide an infrared sensor manufacturing method that can increase the response speed.

In order to solve the above problems, the present invention provides a sensor region having an infrared absorption film and a support beam, and a wiring having a wiring, which are isolated by a silicon oxide film for device isolation formed directly on a silicon substrate. A method of manufacturing an infrared sensor comprising a region , wherein the step of thermally oxidizing the surface of the substrate in the wiring region to form an oxide film and the step of removing the oxide film are performed at least once, A silicon oxide film located at the lowest position among at least one silicon oxide film formed on the silicon substrate in the wiring region, all of the bottom surface of the infrared absorption film and at least a part of the bottom surface of the support beam The sensor is formed at a position higher than the bottom surface of the sensor, and at least when the slit for heat separation between the infrared absorption film and the support beam is formed. A height of the top surface height and the wiring area of the top surface of the band to be the same, it has a configuration that.

According to the present invention, (1) the height of the uppermost surface of the sensor region and the height of the uppermost surface of the wiring region are made the same, and the area for the infrared absorption film is increased by opening the slit for heat separation narrowly. The sensitivity of the infrared sensor is increased, and (2) all of the bottom surface of the infrared absorption film is formed of the silicon oxide film positioned at the lowest position of at least one silicon oxide film formed on the silicon substrate in the wiring region. By forming it at a position higher than the bottom surface, it is possible to provide a method for manufacturing an infrared sensor that can reduce the thermal time constant and increase the response speed.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings described below, components having the same function are denoted by the same reference numerals, and repeated description thereof is omitted.
Embodiment 1
<Constitution>
1A is a plan view of the infrared sensor of the present embodiment, FIG. 1B is a cross-sectional view taken along the line M1-M2 in FIG. 2A, and FIG. 2A is a detection of an output of an electrical signal in the infrared sensor array. A block diagram and (b) are circuit diagrams of an infrared sensor array.
2A and 2B, 200 is an infrared sensor array, 201 is a counter, 202 is an X-decoder, 203 is a Y-decoder, 204 is a MOSFET, Vref is a bias voltage, GND is ground, Y * is * The pixel selection signal in the row, X * is the pixel selection signal in the * column, CLK is the sampling clock, and Vout is the infrared sensor output.
As shown in FIGS. 2A and 2B, the infrared sensor array 200 includes an infrared sensor and digital circuits such as a counter 201, an X-decoder 202, and a Y-decoder 203 that perform sampling. Since a plurality of infrared sensors are arranged in an array, a MOSFET 204 which is a pixel selection switch element is built in the infrared sensor array 200 as shown in FIG.
Therefore, a plan view and a sectional view of each pixel inside the infrared sensor array 200 are as shown in FIGS. 1A and 1B, respectively. 1A and 1B, 1 is a silicon substrate, 301 is a region where a sensor is formed (hereinafter referred to as a sensor region), 302 is a region where wiring is formed (hereinafter referred to as a wiring region), 100 is an infrared absorption film, 101 is a support beam, 19 is a slit for performing thermal separation between the infrared absorption film 100 and the support beam 101, 12, 16 are aluminum wirings, 2, 7, 10, and 13 are silicon oxide films , 500 are cavities formed in the silicon substrate 1. In FIG. 1A, the inside of a thick black frame where the infrared sensor is formed is a sensor region 301, and the other region is a wiring region 302. That is, the infrared sensor and the MOSFET 204 that is the selection switch element are arranged close to each other, and a plurality of wiring layers are arranged. In the present embodiment, an example in which two layers of aluminum wirings 12 and 16 are formed is shown, but there may be three layers and four layers.

When the upper surface of the infrared sensor is displaced from the upper surface of the wiring region 302 through which the wiring of the infrared sensor passes, the slit 19 for performing thermal separation between the infrared absorbing film 100 and the support beam 101 is provided with RIE ( When formed by anisotropic etching such as Reactive Ion Etching, the slit 19 has a tapered cross-sectional shape. Therefore, the slit 19 in the sensor region 301 and the slit 19 adjacent to the wiring region 302 have a width. It will be different. Further, the width of the slit 19 closer to the outer side near the wiring region 302 in the sensor region 301 is different from that of the slit 19 closer to the inner side. Therefore, in the manufacturing process, the width of the slit 19 deviates from the minimum dimension and becomes large. If the upper surface of the sensor region 301 and the upper surface of the wiring region 302 when the slit 19 is formed are flat and at the same height, the width of the slit 19 can be formed uniformly.
Further, in order to increase the thermal resistance of the support beam 101, the support beam 101 is thin, the thermal time constant is increased, and the infrared absorption film 100 is also required to be thin so that the response speed is not slowed down.
In the present invention, in order to realize these simultaneously, even if the number of wiring layers in the wiring region 302 increases and the wiring region 302 becomes thicker, the sensor region 301 and the wiring region 302 have the same height. In addition, the manufacturing method of the infrared sensor and the infrared ray capable of improving the processing accuracy of the slit 19, maximizing the area (aperture ratio) of the infrared absorption film 100, and keeping the thickness of the infrared absorption film 100 and the support beam 101 to a minimum. A sensor is provided.

<Production method>
3 to 11 are process diagrams showing a method of manufacturing the infrared sensor according to the present embodiment. In each figure, (a) is a plan view of the infrared sensor, and (b) is a cut along M1-M2 of (a). It is sectional drawing in a line.
The description of the method for manufacturing the MOSFET in the wiring region 302 is omitted, and only the manufacturing process of the gate wiring and the aluminum wiring will be described.
First, as shown in FIG. 3, in the silicon substrate 1, a known LOCOS (Local Oxidation)
of silicon) is used to form a silicon oxide film (SiO ₂ ) 2 (the mask layer made of a silicon nitride film during oxidation is not shown), and the sensor region 301 and the wiring region 302 are separated from each other. In FIG. 3A, reference numeral 303 denotes a region where a MOSFET is formed (hereinafter referred to as a MOSFET region).
Next, an etching sacrificial layer 3 made of polysilicon is formed on the entire surface of the sensor region 301.
Next, in order to determine an etching region for forming a cavity in the silicon substrate 1, boron (B) ions are ion-implanted to form an etching stopper 4.

Next, as shown in FIG. 4, in the wiring region 302, the gate wiring 5 made of the polysilicon of the MOSFET in the Y column is formed.
Next, an etching sacrificial layer 6 made of polysilicon is further laminated on the etching sacrificial layer 3 made of polysilicon, and the height of the sensor region 301 is raised. The thickness of the etching sacrificial layer 6 is such that the wiring at the highest position in the sensor region 301 and the wiring at the highest position in the wiring region 302 are at the same position. In the plan view of (a), reference numerals 6 a and 6 b denote partial regions of the etching sacrificial layer 6. FIG. 4C is a cross-sectional view taken along the line N1-N2 in FIG. Since the step between the etching sacrificial layer 6 and the etching stopper 4 becomes large, as shown in (a), in order to maintain a constant height so that the thermopile wired over both of the steps does not break by this step. In addition, the etching sacrificial layer 6 is also formed in the regions 6a and 6b. The cross section is shown in (c).

Next, as shown in FIG. 5, a silicon oxide film (SiO ₂ ) 7 is deposited on the entire surface of the silicon substrate 1 by a known method. Note that the silicon oxide film 7 is not shown in the plan view of (a) (hereinafter, for the sake of easy understanding, members such as layers are not shown in the plan view of (a)).
Next, as shown in FIG. 6, a thermopile 400 is formed by forming a P-type polysilicon layer 8 and an N-type polysilicon layer 9 in a predetermined shape in the sensor region 301.
Next, a silicon oxide film (SiO ₂ ) 10 is formed on the entire surface of the silicon substrate 1 in order to insulate the gate wiring 5 and the thermopile 400.
Next, as shown in FIG. 7, the silicon oxide films 7 and 10 are selectively etched to form contact holes 11.

Next, as shown in FIG. 8, aluminum wiring 12 is formed.
Next, a silicon oxide film (SiO ₂ ) 13 is formed on the entire surface of the silicon substrate 1 in order to insulate the aluminum wiring 12.
Next, the silicon oxide film 13 is selectively etched to form a second contact hole 14.

Next, as shown in FIG. 9, the second aluminum wiring 16 is formed.
Next, a silicon oxide film (SiO ₂ ) 17 is formed on the entire surface of the silicon substrate 1 in order to insulate the aluminum wiring 16. In FIG. 9B, x is the height of the uppermost surface of the wiring region 302 (height after completion of the infrared sensor; see FIG. 11B), and y is the aluminum at the highest position in the sensor region 301. The height of the upper surface of the wiring 16, z is the height of the upper surface of the aluminum wiring 16 at the highest position in the wiring region 302. The positional relationship at this time determines the thickness of the etching sacrificial layer 6 when the etching sacrificial layer 6 is formed. The positional relationship satisfies x ≧ y ≧ z.

Next, as shown in FIG. 10, the silicon oxide films 17 and 13 are formed by CMP (Chemical Mechanical
Polishing) or removal by etch-back to make the upper surface of the aluminum wiring 16 in the sensor region 301 thin enough to reduce the level difference between the sensor region 301 and the wiring region 302. By this step, the thickness of both the infrared absorption film and the support beam can be reduced. That is, since the silicon oxide film constituting the support beam in the sensor region 301 can be thinned, sensitivity is increased. Further, since the infrared absorbing film can be made thin, the heat capacity can be reduced, the thermal time constant is reduced, and the response speed is increased.
Next, in the sensor region 301, the silicon oxide films 13, 10, and 7 are selectively etched to form the slits 19. The sensor region 301 and the wiring region 302 are planarized by the process of removing the silicon oxide films 17 and 13 by CMP or etchback, and the silicon oxide films 13, 10 and 7 in the sensor region 301 are flattened. Since the thickness of the slit 19 is reduced, the processing accuracy of the slit 19 is good. That is, the slit 19 can be formed with a narrow width.

  Next, as shown in FIG. 11, using a strong alkaline solution such as hydrazine from the slit 19, the sacrificial etching layers 6 and 3 made of polysilicon and the silicon substrate 1 are connected to the (111) plane of the silicon substrate 1. Is etched to form a cavity in a pyramidal shape from the upper surface of the silicon substrate 1, and the infrared absorption film 100 and the support beam 101 are separated. Thereby, finally, both the infrared absorption film 100 and the support beam 101 can be formed thin. As a result, the heat capacity of the infrared absorption film 100 decreases, the thermal time constant decreases, and the response speed increases. In addition, since both the support beams 101 can be formed thin, the thermal resistance can be lowered and the sensitivity can be increased.

As described above, in the method of manufacturing the infrared sensor according to the present embodiment, as shown in FIGS. 1 and 11, the infrared absorption film 100 and the support beam 101 in the sensor region 301 are formed on the etching sacrificial layers 3 and 6. As a result, the bottom surface A of the infrared absorption film 100 and the bottom surface B of the support beam 101 are formed at a position higher than the bottom surface C of the wiring region 302.
Further, as shown in FIG. 9, the height y of the uppermost surface of the aluminum wiring 16 at the highest position in the sensor region 301 is set to the height of the uppermost surface of the aluminum wiring 16 at the highest position in the wiring region 302. It is formed at a position equal to or higher than z and lower than the height x of the uppermost surface of the wiring region 302.
Furthermore, in the infrared sensor of the present embodiment, the bottom surfaces of the infrared absorption film 100 and the support beam 101 are formed at a position higher than the bottom surface of the wiring region 302, and the aluminum wiring 16 at the highest position in the sensor region 301 is formed. The height y of the upper surface is equal to or higher than the height z of the upper surface of the aluminum wiring 16 at the highest position in the wiring region 302, and the height x of the uppermost surface of the wiring region 302. Is in a lower position.

As described above, the height y of the upper surface of the aluminum wiring 16 at the uppermost portion of the sensor region 301 is equal to or higher than the height z of the upper surface of the aluminum wiring 16 at the uppermost portion of the wiring region 302. The thickness of the film 100 and the support beam 101 can be reduced to the limit at which the upper surface of the aluminum wiring 16 in the sensor region 301 is exposed, leading to an improvement in the thermal resistance of the support beam 101 and a reduction in the heat capacity of the infrared absorption film 100. The response speed can be increased by increasing the sensitivity and reducing the thermal time constant.
Further, by making the height y of the upper surface of the aluminum wiring 16 at the uppermost part of the sensor region 301 lower than the height x of the uppermost surface of the wiring region 302, the uppermost silicon oxide films 17 and 13 in FIG. During etching, the top surface can be planarized.
Further, by laying thick polysilicon etching sacrificial layers 6 and 3 under both the infrared absorption film 100 and the support beam 101, the bottom surfaces of both can be formed on the same plane. Can be made thinner. Moreover, since the thickness of the infrared absorption film 100 and the support beam 101 can be reduced and both are on the same plane, the width of the slit 19 can be reduced. Therefore, the area of the infrared ray absorbing film 100 can be increased by the narrowed portion, the aperture ratio can be improved, and the sensitivity can be improved.

<< Embodiment 2 >>
12-17 is process drawing which shows the manufacturing method of the infrared sensor of this Embodiment, In each figure, (a) is a top view of an infrared sensor, (b) is M1-M2 cutting | disconnection of (a). It is sectional drawing in a line. In FIG. 12, (b) to (d) are cross-sectional views.
The description of the method for manufacturing the MOSFET in the wiring region 302 is omitted, and only the manufacturing process of the gate wiring and the aluminum wiring will be described.
First, as shown in FIG. 12B, in the silicon substrate 1, the entire surface of the wiring region 302 is thermally oxidized by the LOCOS method to form a silicon oxide film (SiO ₂ ) 21 (on the sensor region 301 during oxidation). The mask layer made of the silicon nitride film is not shown).
Next, as shown in FIG. 12C, the silicon oxide film 21 in the LOCOS region is removed by etching or the like. In the silicon oxide film 21 formed by the LOCOS method, 55% of the total thickness of the silicon oxide film 21 is formed on the original surface before the silicon oxide film 21 is formed, and the remaining 45% is formed on the surface. Formed on the lower side. For this reason, when the silicon oxide film 21 is removed, the surface of the silicon substrate 1 is exposed below the original surface.
12B and 12C are repeated, and the height of the wiring region 302 is lowered to a predetermined position. If the height of the wiring region 302 can be lowered to a predetermined position, these two steps can be performed only once.
Next, as shown in FIG. 12D, the silicon oxide film 2 is formed by the LOCOS method (the mask layer made of the silicon nitride film on the sensor region 301 and the wiring region 302 at the time of oxidation is not shown), and the sensor region The element 301 is separated from the wiring region 302.

Next, as shown in FIG. 13, an etching sacrificial layer 3 made of polysilicon is formed on the entire surface of the sensor region 301. Note that in the plan view of (a), members such as layers are appropriately omitted for easy understanding.
Next, in order to determine an etching region for forming a cavity in the silicon substrate 1, boron (B) ions are ion-implanted to form an etching stopper 4.

Next, in the wiring region 302, the gate wiring 5 made of polysilicon of the MOSFET in the Y column is formed.
Next, the silicon nitride film 22 is formed on the etching sacrificial layer 3 and the etching stopper 4 in the sensor region 301.

Next, as shown in FIG. 14, a thermopile 400 is formed by forming a P-type polysilicon layer 8 and an N-type polysilicon layer 9 in a predetermined shape in the sensor region 301.
Next, a silicon oxide film (SiO ₂ ) 10 is formed on the entire surface of the silicon substrate 1 in order to insulate the gate wiring 5 and the thermopile 400.
Next, the silicon oxide film 10 is selectively etched to form contact holes 11.
Next, the aluminum wiring 12 is formed.
Next, a silicon oxide film (SiO ₂ ) 13 is formed on the entire surface of the silicon substrate 1 in order to insulate the aluminum wiring 12.

Next, as shown in FIG. 15, the silicon oxide film 13 is selectively etched to form a second contact hole 14.
Next, the second aluminum wiring 16 is formed.
Next, a silicon oxide film (SiO ₂ ) 17 is formed on the entire surface of the silicon substrate 1 in order to insulate the aluminum wiring 16.

Next, as shown in FIG. 16, the silicon oxide films 17 and 13 are removed by CMP or etch-back so that the upper surface of the aluminum wiring 16 in the sensor region 301 is not exposed, and the sensor region 301 and the wiring region are removed. The level difference with 302 is reduced and flattened. By this step, the thickness of both the infrared absorption film and the support beam can be reduced. That is, since the silicon oxide film constituting the support beam in the sensor region 301 can be thinned, sensitivity is increased. Further, since the infrared absorbing film can be made thin, the heat capacity can be reduced, the thermal time constant is reduced, and the response speed is increased.
Next, in the sensor region 301, the silicon oxide films 13, 10, and 7 are selectively etched to form the slits 19. The sensor region 301 and the wiring region 302 are planarized by the process of removing the silicon oxide films 17 and 13 by CMP or etchback, and the silicon oxide films 13, 10 and 7 in the sensor region 301 are flattened. Since the thickness of the slit 19 is reduced, the processing accuracy of the slit 19 is good. That is, the slit 19 can be formed with a narrow width.

  Next, as shown in FIG. 11, using a strong alkaline solution such as hydrazine from the slit 19, the sacrificial etching layers 6 and 3 made of polysilicon and the silicon substrate 1 are connected to the (111) plane of the silicon substrate 1. Is etched to form a cavity in a pyramidal shape from the upper surface of the silicon substrate 1 to separate the infrared absorbing film 100 and the support beam 101. Thereby, finally, both the infrared absorption film 100 and the support beam 101 can be formed thin. As a result, the heat capacity of the infrared absorption film 100 decreases, the thermal time constant decreases, and the response speed increases. In addition, since both the support beams 101 can be formed thin, the thermal resistance can be lowered and the sensitivity can be increased.

As described above, in the method for manufacturing the infrared sensor according to the present embodiment, the step of forming the oxide film by thermally oxidizing the surface of the silicon substrate 1 in the wiring region 302 and the step of removing the oxide film are performed at least once (that is, By performing this once or a plurality of times, the bottom surface of the infrared absorption film 100 and the bottom surface of the support beam 101 in the sensor region 301 are formed at a position higher than the bottom surface of the wiring region 302.
In the present embodiment, the height of the surface of the silicon substrate 1 on which the wiring region 302 is formed by the process as described above can be lowered, so that the final height of the sensor region 301 and the height of the wiring region 302 can be reduced. Can be controlled. As a result, the height y (see FIG. 9) of the upper surface of the aluminum wiring 16 at the uppermost portion of the sensor region 301 is the same as or higher than the height z of the upper surface of the aluminum wiring 16 at the uppermost portion of the wiring region 302. Thus, the thickness of the infrared absorption film 100 and the support beam 101 can be reduced to the limit where the upper surface of the aluminum wiring 16 in the sensor region 301 is exposed, and the thermal resistance of the support beam 101 is improved. This leads to a reduction in heat capacity, and an increase in sensitivity and an increase in response speed due to a reduction in thermal time constant can be realized.

<< Embodiment 3 >>
18 (a) to 18 (d) are process diagrams showing a method of manufacturing the infrared sensor of the present embodiment, (a) is a plan view of the infrared sensor, and (b) to (d) are M1 of (a). It is sectional drawing in a -M2 cutting line.
The description of the method for manufacturing the MOSFET in the wiring region 302 is omitted, and only the manufacturing process of the gate wiring and the aluminum wiring will be described.
First, as shown in FIG. 18B, the entire surface of the wiring region 302 is covered with a silicon oxide film (SiO ₂ ) 31 in the silicon substrate 1.
Next, as shown in FIG. 18C, an epitaxial growth layer 32 made of single crystal silicon having the same crystal orientation as that of the silicon substrate 1 is epitaxially grown on the entire surface of the sensor region 301 to a predetermined height. The number of times of epitaxial growth may be one or more.
Next, the silicon deposited on the wiring region 302 and the silicon oxide film 31 are etched and removed. Thereafter, as shown in FIG. 18D, the silicon oxide film 2 is formed by the LOCOS method (the mask layer made of the silicon nitride film on the sensor region 301 and the wiring region 302 at the time of oxidation is not shown), and the sensor region 301 is formed. And the wiring region 302 are separated from each other.
The subsequent steps are the same as those in the second embodiment shown in FIGS.

As described above, the infrared sensor manufacturing method according to the present embodiment forms the epitaxial growth layer 32 on the silicon substrate 1 in the sensor region 301 at least once, so that the bottom surfaces of the infrared absorption film 100 and the support beam 101 in the sensor region 301 are formed. Is formed at a position higher than the bottom surface of the wiring region 302.
In the present embodiment, the height of the surface of the silicon substrate 1 on which the sensor region 301 is formed can be increased by the process as described above, so that the final height of the sensor region 301 and the height of the wiring region 302 are increased. Can be controlled. As a result, the height y (see FIG. 9) of the upper surface of the aluminum wiring 16 at the uppermost portion of the sensor region 301 is the same as or higher than the height z of the upper surface of the aluminum wiring 16 at the uppermost portion of the wiring region 302. Thus, the thickness of the infrared absorption film 100 and the support beam 101 can be reduced to the limit where the upper surface of the aluminum wiring 16 in the sensor region 301 is exposed, and the thermal resistance of the support beam 101 is improved. This leads to a reduction in heat capacity, and an increase in sensitivity and an increase in response speed due to a reduction in thermal time constant can be realized.
The embodiment described above is described in order to facilitate understanding of the present invention, and is not described in order to limit the present invention. Therefore, each element disclosed in the above embodiment includes all design changes and equivalents belonging to the technical scope of the present invention. For example, in the above-described embodiment, the thermopile type infrared sensor has been described. However, the thermopile type infrared sensor is not limited to the thermopile type, and can be applied to other diode type or bolometer type infrared sensors.

(A) is a top view of the infrared sensor of Embodiment 1 of this invention, (b) is sectional drawing in the M1-M2 cutting line of (a). (A) is a detection block diagram of the output of the electric signal in the infrared sensor array of Embodiment 1 of this invention, (b) is a circuit diagram of an infrared sensor array. It is process drawing which shows the manufacturing method of the infrared sensor of Embodiment 1 of this invention. It is process drawing which shows the manufacturing method of the infrared sensor of Embodiment 1 of this invention. It is process drawing which shows the manufacturing method of the infrared sensor of Embodiment 1 of this invention. It is process drawing which shows the manufacturing method of the infrared sensor of Embodiment 1 of this invention. It is process drawing which shows the manufacturing method of the infrared sensor of Embodiment 1 of this invention. It is process drawing which shows the manufacturing method of the infrared sensor of Embodiment 1 of this invention. It is process drawing which shows the manufacturing method of the infrared sensor of Embodiment 1 of this invention. It is process drawing which shows the manufacturing method of the infrared sensor of Embodiment 1 of this invention. It is process drawing which shows the manufacturing method of the infrared sensor of Embodiment 1 of this invention. It is process drawing which shows the manufacturing method of the infrared sensor of Embodiment 2 of this invention. It is process drawing which shows the manufacturing method of the infrared sensor of Embodiment 2 of this invention. It is process drawing which shows the manufacturing method of the infrared sensor of Embodiment 2 of this invention. It is process drawing which shows the manufacturing method of the infrared sensor of Embodiment 2 of this invention. It is process drawing which shows the manufacturing method of the infrared sensor of Embodiment 2 of this invention. It is process drawing which shows the manufacturing method of the infrared sensor of Embodiment 2 of this invention. It is process drawing which shows the manufacturing method of the infrared sensor of Embodiment 3 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Silicon substrate 2, 7, 10, 13, 17, 21, 31 ... Silicon oxide film 3, 6, 6a, 6b ... Etching sacrificial layer 4 ... Etching stopper 5 ... Gate wiring 8 ... P-type polysilicon layer 9 ... N Type polysilicon layers 11, 14 ... contact holes 12, 16 ... aluminum wiring 19 ... slit 22 ... silicon nitride film 31 ... epitaxial growth layer 100 ... infrared absorption film 101 ... support beam 200 ... infrared sensor array 201 ... counter 202 ... X-decoder 203 ... Y-decoder 204 ... MOSFET
301 ... Sensor region 302 ... Wiring region 303 ... MOSFET region 400 ... Thermopile 500 ... Cavity Vref ... Bias voltage GND ... Ground Y * ... * Pixel selection signal X * in row * Pixel selection signal CLK in column * Sampling clock Vout ... Infrared sensor output

Claims (3)

The element was isolated by the element isolation silicon oxide film directly formed on the silicon substrate.
A sensor region having an infrared absorption film and a support beam, and a method for manufacturing an infrared sensor comprising a wiring region having wiring,
Thermally oxidizing the surface of the substrate in the wiring region to form an oxide film;
Performing the step of removing the oxide film at least once,
A silicon oxide located at the lowest position of at least one silicon oxide film formed on the silicon substrate in the wiring region, including all of the bottom surface of the infrared absorption film and at least a part of the bottom surface of the support beam. Formed higher than the bottom of the membrane,
And,
At least when the slit for heat separation between the infrared absorption film and the support beam is formed, the height of the uppermost surface of the sensor region is made equal to the height of the uppermost surface of the wiring region. A method for manufacturing an infrared sensor. The element was isolated by the element isolation silicon oxide film directly formed on the silicon substrate.
A sensor region having an infrared absorption film and a support beam, and a method for manufacturing an infrared sensor comprising a wiring region having wiring,
The entire surface of the wiring region is covered with a silicon oxide film, and then an epitaxial growth layer made of single crystal silicon having the same crystal orientation as that of the silicon substrate is formed on the entire surface of the sensor region at least once. By etching away the silicon and silicon oxide deposited on the area,
A silicon oxide located at the lowest position of at least one silicon oxide film formed on the silicon substrate in the wiring region, including all of the bottom surface of the infrared absorption film and at least a part of the bottom surface of the support beam. Formed higher than the bottom of the membrane,
And,
At least when the slit for heat separation between the infrared absorption film and the support beam is formed, the height of the uppermost surface of the sensor region is made equal to the height of the uppermost surface of the wiring region. A method for manufacturing an infrared sensor. The height y of the top surface of the wiring at the highest position in the sensor region is equal to or higher than the height z of the top surface of the wiring at the highest position in the wiring region; and The method for manufacturing an infrared sensor according to claim 1, wherein the infrared sensor is formed at a position lower than a height x of the uppermost surface of the wiring region.

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