Light detection device

Abstract

The present disclosure relates to a light detection device that makes it possible to suppress differences in sensitivity between different color pixels. The light detection device comprises a pixel array in which a plurality of pixels are arranged two-dimensionally. Each pixel includes a photoelectric conversion unit formed on a semiconductor substrate, and a color filter layer that allows light of a prescribed wavelength region to pass therethrough and be incident on the photoelectric conversion unit. At least one of the number, pitch, and depth of recessed portions formed on the light incident surface of the semiconductor substrate differs between pixels of a first color filter of the color filter layer and pixels of a second color filter of the color filter layer. The technology of the present disclosure can be applied to, for example, a light detection device that receives light in the visible region and light in the infrared region, generates an imaging signal corresponding to the received light amount, and outputs the imaging signal.

Description

Optical detection device

[0001] The present disclosure relates to an optical detection device, and particularly to an optical detection device capable of suppressing a sensitivity difference between pixels of different colors.

[0002] In a solid-state imaging device, for the purpose of suppressing color mixing when pixels are miniaturized, there is a pixel structure provided with an inter-pixel separation portion that forms trenches at the boundary portions of pixels to separate the photoelectric conversion portions of each pixel (see, for example, Patent Document 1).

[0003] By providing an inter-pixel separation portion, the color mixing suppression effect increases. However, due to the increase in the color mixing suppression effect, the influence of the physical characteristics of the color filter may become more visible. For example, a difference in sensitivity may occur in the infrared region (NIR region) because the refractive index characteristics of the first color and the second color among R, G, and B of the color filter are different. Also, for example, a difference in sensitivity may occur in the infrared region because the transmittance of the first color and the second color among R, G, and B of the color filter is different.

[0004] Japanese Patent Application Laid-Open No. 2021-82724

[0005] In the above-mentioned Patent Document 1, a configuration for suppressing the sensitivity difference between the central portion and the peripheral portion of the pixel region has been proposed, but no particular measures have been taken for the sensitivity difference between pixels of different colors, which are pixels having different colors of the color filter.

[0006] The present disclosure has been made in view of such a situation, and is intended to suppress the sensitivity difference between pixels of different colors.

[0007] The optical detection device according to the first aspect of the present disclosure includes a pixel array in which a plurality of pixels are two-dimensionally arranged, and the pixels have a photoelectric conversion portion formed on a semiconductor substrate and a color filter layer that allows light in a predetermined wavelength region to pass through and is incident on the photoelectric conversion portion. At least one of the number, pitch, or depth of the recesses formed on the light incident surface of the semiconductor substrate is different between the pixel of the first color filter and the pixel of the second color filter of the color filter layer.

[0008] In a first aspect of this disclosure, a pixel array is provided in which a plurality of pixels are arranged in two dimensions, and each pixel is provided with a photoelectric conversion unit formed on a semiconductor substrate and a color filter layer that allows light in a predetermined wavelength range to pass through and be incident on the photoelectric conversion unit, and at least one of the number, pitch, or depth of recesses formed on the light incident surface of the semiconductor substrate differs between the pixels of the first color filter and the pixels of the second color filter of the color filter layer.

[0009] A second aspect of the present disclosure of a photodetector includes a pixel array in which a plurality of pixels are arranged in two dimensions, wherein each pixel has a photoelectric conversion unit formed on a semiconductor substrate and a color filter layer that allows light in a predetermined wavelength range to pass through and be incident on the photoelectric conversion unit, and the color filter layer has a first color filter and a second color filter with different film thicknesses, and a white filter having a thinner film thickness than the second color filter above or below the first color filter.

[0010] In a second aspect of this disclosure, a pixel array is provided in which a plurality of pixels are arranged in two dimensions, and each pixel is provided with a photoelectric conversion unit formed on a semiconductor substrate and a color filter layer that allows light in a predetermined wavelength range to pass through and is incident on the photoelectric conversion unit, and the color filter layer is provided with a first color filter and a second color filter having different film thicknesses, and a white filter is provided above or below the first color filter having a thinner film thickness than the second color filter.

[0011] The light detection device may be a standalone device or a module incorporated into another device.

[0012] This is a block diagram showing an example configuration of an imaging system to which the technology of this disclosure is applied. This is a diagram showing an example configuration of a photodetector. This is a diagram showing an example of a pixel circuit configuration. This is a cross-sectional view showing a first example of a pixel configuration. This is a plan view showing the arrangement of the color filter layer and the uneven portion of the first example. This is a diagram showing the sensitivity characteristics of the color filter. This is a cross-sectional view showing a second example of a pixel configuration. This is a plan view showing the arrangement of the color filter layer and the uneven portion of the second example. This is a plan view showing modified versions of the first and second examples. This is a cross-sectional view showing a third example of a pixel configuration. This is a cross-sectional view showing a fourth example of a pixel configuration. This is a plan view showing the arrangement of the color filter layer and the uneven portion of the fourth example. This is a cross-sectional view showing a fifth example of a pixel configuration. This is a cross-sectional view showing a sixth example of a pixel configuration. This is a plan view showing the arrangement of the MIM capacitive elements of the sixth example. This is a diagram illustrating the effect of the arrangement of the MIM capacitive elements of the sixth example. This is a plan view showing a modified version of the sixth example. This is a cross-sectional view showing a seventh example of a pixel configuration. This is a cross-sectional view showing an eighth example of a pixel configuration. This is a diagram illustrating the effect of different color filter film thicknesses. This is a cross-sectional view showing a ninth example of a pixel configuration. This is a plan view showing the arrangement of the color filter layer of the ninth example. This is a cross-sectional view showing a modified example of the ninth configuration. This is a cross-sectional view showing a tenth example of a pixel configuration. This is a cross-sectional view showing an eleventh example of a pixel configuration. This is a block diagram showing an example of an electronic device to which the technology of this disclosure is applied. This is a diagram illustrating an example of the use of an image sensor.

[0013] The following describes embodiments for implementing the technology of this disclosure (hereinafter referred to as "embodiments") with reference to the attached drawings. The description will proceed in the following order: 1. Example of overall configuration of the imaging system 2. Example of configuration of the light detection device 3. Example of pixel circuit configuration 4. Example of first pixel configuration 5. Example of second pixel configuration 6. Example of third pixel configuration 7. Example of fourth pixel configuration 8. Example of fifth pixel configuration 9. Example of sixth pixel configuration 10. Example of seventh pixel configuration 11. Example of eighth pixel configuration 12. Summary of first to eighth configurations 13. Example of ninth pixel configuration 14. Example of tenth pixel configuration 15. Example of eleventh pixel configuration 16. Summary of ninth to eleventh configurations 17. Combinations of first to eleventh configurations 18. Example of electronic device configuration 19. Example of image sensor usage

[0014] In this specification and drawings, identical or similar parts are denoted by the same or similar reference numerals, thereby omitting redundant explanations as appropriate. The drawings are schematic, and the relationship between thickness and planar dimensions, the ratio of the thickness of each layer, etc., may differ from actual dimensions. Furthermore, there may be parts where the dimensional relationships and ratios differ between drawings.

[0015] Furthermore, the definitions of directions such as up and down in the following explanation are merely for explanatory convenience and do not limit the technical concept of this disclosure. For example, if an object is rotated 90° and observed, up and down will be converted to left and right and read accordingly, and if it is rotated 180° and observed, up and down will be inverted and read accordingly.

[0016] The technology disclosed herein can be applied to all types of photodetectors having a pixel array in which pixels are arranged in a matrix in two dimensions, and which convert incident light into photoelectric light and output a pixel signal corresponding to the amount of light. The light to be detected includes both visible light (first wavelength region) including wavelengths such as R (Red), G (Green), and B (Blu), and invisible light (second wavelength region) such as infrared light. The photodetector can be used as a solid-state imaging device that generates and outputs an imaging signal corresponding to the amount of incident light, or as a light-receiving device (distance sensor) in a distance measuring system that receives reflected light (reflected light) from infrared light irradiated as active light and measures the distance to the subject using a direct ToF or indirect ToF method.

[0017] <1. Example of Overall Configuration of Imaging System> Figure 1 is a block diagram showing an example of the configuration of an imaging system to which the technology of this disclosure is applied.

[0018] The imaging system 1 shown in Figure 1 comprises a control device 11, a light source device 12, and a light detection device 13.

[0019] The control device 11 controls the operation of the entire imaging system 1. Specifically, the control device 11 outputs an imaging trigger, which is a timing signal that causes imaging to be performed according to the operating mode, to both the light source device 12 and the light detection device 13, or to the light detection device 13. For example, in the first operating mode in which infrared light is irradiated from the light source device 12 to image the subject 20, the imaging trigger is output to both the light source device 12 and the light detection device 13, and in the second operating mode in which infrared light is not irradiated to image the subject 20, the imaging trigger is output to the light detection device 13. The first operating mode can be, for example, a night shooting mode, and the second operating mode can be a daytime shooting mode. The control device 11 acquires the image signal of the image captured by the light detection device 13 in response to the imaging trigger and outputs it to the outside. The control device 11 may perform predetermined image processing using the acquired image signal, such as demosaicing or white balance processing, and output the processed image signal.

[0020] The light source device 12, for example, has a light source that emits infrared light, and irradiates the subject 20 with infrared light based on an imaging trigger from the control device 11.

[0021] The light detection device 13 is composed of a CMOS image sensor, which is an image sensor. Based on an imaging trigger from the control device 11, it generates an image signal of the captured image of the subject 20 and outputs it to the control device 11. In the first operating mode in which infrared light is emitted, the light detection device 13 receives the light that is incident after infrared light irradiated from the light source device 12 is reflected by the subject 20, and generates and outputs an imaging signal according to the amount of light received. On the other hand, in the second operating mode in which infrared light is not emitted, the light detection device 13 receives the light that is incident after visible light is reflected by the subject 20, and generates and outputs an imaging signal according to the amount of light received. When the incident light includes both infrared light and visible light, the light detection device 13 may separate the imaging signal which includes both infrared light and visible light into infrared light and visible light, and generate and output an image signal for the first captured image using infrared light and an image signal for the second captured image using visible light. The process of separating the imaging signal into infrared and visible light signals, and generating the image signal for the first image captured using infrared light and the image signal for the second image captured using visible light, may be performed by the control device 11 that acquires the image signal from the photodetector 13.

[0022] <2. Example of a light detection device configuration>

[0023] Figure 2 shows an example of the configuration of the light detection device 13.

[0024] The light detection device 13 comprises a pixel array 41 and a peripheral circuit section. The peripheral circuit section includes, for example, a vertical drive unit 42, a column processing unit 43, a horizontal drive unit 44, and a system control unit 45. The light detection device 13 further comprises a signal processing unit 46 and a data storage unit 47. The signal processing unit 46 and the data storage unit 47 may be mounted on the same substrate as the pixel array 41, vertical drive unit 42, etc., or they may be arranged on a separate substrate stacked on top of each other.

[0025] The pixel array 41 has a configuration in which a plurality of pixels 50 are arranged in a two-dimensional matrix in the row direction and the column direction. Here, the row direction refers to the pixel rows of the pixel array 41, in other words, the horizontal arrangement direction, and the column direction refers to the pixel columns of the pixel array 41, in other words, the vertical arrangement direction.

[0026] The pixel 50 has a photoelectric conversion unit that generates and stores an electric charge corresponding to the amount of light received, and a plurality of pixel transistors (so-called MOS transistors). As an example of the circuit configuration of the pixel 50, for example, the configuration described later with reference to Figure 3 can be adopted.

[0027] Furthermore, in the pixel array 41, a pixel drive wiring 51 is routed along the row direction as a row signal line for each pixel row, and a vertical signal line 52 is routed along the column direction as a column signal line for each pixel column. The pixel drive wiring 51 transmits drive signals for driving when reading signals from the pixels 50. In Figure 2, the pixel drive wiring 51 is shown as a single wire, but it is not limited to one wire. One end of the pixel drive wiring 51 is connected to the output terminal corresponding to each row of the vertical drive unit 42.

[0028] The vertical drive unit 42 is composed of a shift register, an address decoder, and the like, and drives each pixel 50 of the pixel array 41 simultaneously or row by row. Together with the system control unit 45, the vertical drive unit 42 constitutes a drive unit that controls the operation of each pixel 50 of the pixel array 41. The specific configuration of the vertical drive unit 42 is not shown in the diagram, but generally it has two scanning systems: a read scanning system and a sweep scanning system.

[0029] The readout scanning system sequentially selects and scans the pixels 50 of the pixel array 41 row by row in order to read a signal from each pixel 50. The signal read from each pixel 50 is an analog signal. The sweep scanning system performs a sweep scan ahead of the readout scan by the readout scanning system by the exposure time of the readout scan row. This sweep scan by the sweep scanning system resets the photoelectric conversion unit of each pixel 50 by sweeping out unwanted charges from the photoelectric conversion unit of the pixels 50 in the readout row. This sweeping out (resetting) of unwanted charges by the sweep scanning system then performs what is known as an electronic shutter operation. Here, an electronic shutter operation refers to the operation of discarding the charge in the photoelectric conversion unit and starting a new exposure (starting charge accumulation). The signal read out by the readout operation of the readout scanning system corresponds to the amount of light received since the immediately preceding readout operation or electronic shutter operation. The period from the readout timing due to the previous readout operation or the sweep timing due to the electronic shutter operation to the readout timing due to the current readout operation becomes the exposure period for pixel 50.

[0030] The signals output from each pixel 50 of the pixel row selected and scanned by the vertical drive unit 42 are input to the column processing unit 43 through each of the vertical signal lines 52 for each pixel column. The column processing unit 43 performs predetermined signal processing on the signals output from each pixel 50 of the selected row through the vertical signal lines 52 for each pixel column of the pixel array 41, and temporarily holds the pixel signals after signal processing.

[0031] Specifically, the column processing unit 43 performs at least noise reduction processing as part of its signal processing, such as CDS (Correlated Double Sampling) processing or DDS (Double Data Sampling) processing. For example, CDS processing removes pixel-specific fixed pattern noise such as reset noise and threshold variations of amplification transistors within pixels. In addition to noise reduction processing, the column processing unit 43 can also be equipped with, for example, an AD (analog-to-digital) conversion function to convert analog pixel signals into digital signals and output them.

[0032] The horizontal drive unit 44 is composed of a shift register, an address decoder, and the like, and sequentially selects the unit circuits corresponding to the pixel rows of the column processing unit 43. Through this selective scanning by the horizontal drive unit 44, the pixel signals processed for each unit circuit in the column processing unit 43 are output sequentially.

[0033] The system control unit 45 is composed of a timing generator that generates various timing signals, and controls the drive of the vertical drive unit 42, column processing unit 43, and horizontal drive unit 44 based on the various timings generated by the timing generator.

[0034] The signal processing unit 46 has at least an arithmetic processing function and performs various signal processing, such as arithmetic processing, on the pixel signal output from the column processing unit 43. The data storage unit 47 temporarily stores the data necessary for the signal processing performed by the signal processing unit 46. The pixel signal processed by the signal processing unit 46 is converted to a predetermined format and output to the outside of the device from the output unit 48.

[0035] <3. Example of Pixel Circuit Configuration> Figure 3 shows an example of a circuit configuration of pixels 50 arranged in a matrix in a pixel array 41.

[0036] Pixel 50 includes a photoelectric conversion unit consisting of a photodiode PD, a transfer transistor TG, a floating diffusion transistor FD, a reset transistor RST, a switching transistor FDG, an amplification transistor AMP, and a selection transistor SEL. The transfer transistor TG, reset transistor RST, switching transistor FDG, amplification transistor AMP, and selection transistor SEL are composed of, for example, n-type MOS transistors (MOS FETs).

[0037] A photodiode (PD) converts incident light into electricity, generating an electric charge (signal charge) corresponding to the amount of incident light received. In a photodiode (PD), the cathode is electrically connected to the source of a transfer transistor (TG), and the anode is electrically connected to a reference potential line (e.g., ground).

[0038] The transfer transistor TG controls the transfer of charge generated by the photodiode PD. When the transfer transistor TG is turned ON, it transfers the charge generated by the photodiode PD to the floating diffusion FD. In the transfer transistor TG, the drain is electrically connected to the floating diffusion FD, and the gate is electrically connected to the pixel drive wiring. This pixel drive wiring is part of the pixel drive wiring 51 described in Figure 2.

[0039] The floating diffusion transistor (FD) is a charge storage unit that temporarily stores the charge transferred from the photodiode (PD), and also a charge-voltage conversion unit that generates a voltage corresponding to the amount of charge. The floating diffusion transistor (FD) is electrically connected to the gate of the amplification transistor (AMP) and the source of the reset transistor (RST).

[0040] The reset transistor RST resets the potential of the floating diffusion FD to a predetermined potential. When the reset transistor RST is turned on by the pixel drive wiring supplied to the gate, it resets the potential of the floating diffusion FD to the potential of the power line VDD. This pixel drive wiring is part of the pixel drive wiring 51 described in Figure 2. When the potential of the floating diffusion FD is reset, the switching transistor FDG is also controlled to be turned on at the same time.

[0041] The switching transistor FDG is used to change the gain of charge-to-voltage conversion in the floating diffusion FD. The drain of the switching transistor FDG is connected to the source of the reset transistor RST and the floating diffusion FD, and the source of the switching transistor FDG is connected to the additional capacitance SubFD. Generally, when shooting in dark places, the pixel signal is small. Based on Q=CV, when performing charge-to-voltage conversion, if the capacitance of the floating diffusion FD (FD capacitance C) is large, the V obtained when converted to voltage by the amplification transistor AMP will be small. On the other hand, in bright places, the pixel signal is large, so if the FD capacitance C is not large enough, the floating diffusion FD will not be able to accept the charge of the photodiode PD. Furthermore, the FD capacitance C needs to be large so that the V obtained when converted to voltage by the amplification transistor AMP does not become too large (in other words, to keep it small). Considering these points, when the switching transistor FDG is turned on, the additional capacitance SubFD due to the switching transistor FDG increases, so the total FD capacitance C increases. On the other hand, when the switching transistor FDG is turned off, the total FD capacitance C decreases. In this way, by switching the switching transistor FDG on and off, the FD capacitance C can be varied, and the conversion efficiency can be switched. The pixel drive wiring supplied to the gate of the switching transistor FDG is a part of the pixel drive wiring 51 described in Figure 2.

[0042] The amplification transistor AMP generates a voltage signal corresponding to the level of the charge accumulated in the floating diffusion FD as a pixel signal. The amplification transistor AMP is connected in series with the selection transistor SEL and is connected to the vertical signal line 52 via the selection transistor SEL. This amplification transistor AMP constitutes a source follower together with the load circuit section in the column signal processing circuit connected to the vertical signal line 52. When the selection transistor SEL is in the on state, the amplification transistor AMP outputs the voltage of the floating diffusion FD to the column signal processing circuit via the vertical signal line 52. The drain of the amplification transistor AMP is connected to the power supply line VDD, and the source of the amplification transistor AMP is connected to the drain of the selection transistor SEL.

[0043] The selection transistor SEL controls the output timing of the pixel signal. The source of the selection transistor SEL is connected to the vertical signal line 52, and the gate of the selection transistor SEL is connected to the pixel drive wiring. When the selection transistor SEL is turned on by the pixel drive wiring supplied to the gate, the pixel signal from the amplification transistor AMP is output to the vertical signal line 52. This pixel drive wiring is a part of the pixel drive wiring 51 described in FIG. 2.

[0044] The circuit configuration of FIG. 3 above is an example of the circuit configuration of the pixel 50, and other configurations may be adopted. For example, in the circuit configuration of FIG. 3, for the photodiode PD and the transfer transistor TG provided in each pixel 50, a floating diffusion FD, a reset transistor RST, a switching transistor FDG, an amplification transistor AMP, and a selection transistor SEL as a readout circuit are provided in a one-to-one correspondence. However, the readout circuit may be provided for the photoelectric conversion sections of a plurality of pixels 50. For example, the photodiode PD and the transfer transistor TG may be provided for each pixel 50, and a configuration in which a readout circuit is provided in units of a plurality of pixels such as two pixels, four pixels, eight pixels, etc. may be adopted.

[0045] <4. First Configuration Example of Pixel> FIG. 4 is a cross-sectional view showing a first configuration example of the pixel 50.

[0046] FIG. 4 is a diagram showing three pixels 50 each having a color filter of R, G, and B arranged side by side for convenience of explanation.

[0047] The pixel 50 according to the first configuration example includes a semiconductor substrate (silicon substrate) 101 using, for example, silicon (Si) as a semiconductor, and a wiring layer 102 formed on the first surface FA side of the semiconductor substrate 101. In FIG. 4, the first surface FA of the semiconductor substrate 101 on which the wiring layer 102 is formed on the lower side is the front surface of the semiconductor substrate 101, and the second surface SA of the semiconductor substrate 101 on the upper side in FIG. 4 is the back surface of the semiconductor substrate 101, which is a light incident surface (light receiving surface) on which light is incident. Therefore, the light detection device 13 having the pixel 50 is a back-illuminated type light detection device in which light is incident from the back surface side of the semiconductor substrate 101.

[0048] In the description of the cross-sectional view of this specification, for convenience, the light incident side of the semiconductor substrate 101 may be referred to as "upper", "upper side", "above", "upper layer", and the side opposite to the light incident side may be referred to as "lower", "lower side", "below", "lower layer".

[0049] In the semiconductor substrate 101, for example, an N-type (second conductivity type) semiconductor region 112 is formed for each pixel 50 in a P-type (first conductivity type) semiconductor region 111, whereby a photodiode PD is formed in pixel units. The photodiode PD can photoelectrically convert light in the visible region (first wavelength region) or light in the infrared region (second wavelength region). The thickness of the semiconductor substrate 101 may be an arbitrary thickness, but in order to efficiently photoelectrically convert incident light in the infrared region, which is a long wavelength region, it is preferably, for example, 4 μm or more. The N-type semiconductor region 112 constitutes a charge storage region for storing charges generated by the photodiode PD. The P-type semiconductor regions 111 provided on both the front and back surfaces of the semiconductor substrate 101 also serve as hole charge storage regions for suppressing dark current. <00000�9>

[0050] At the pixel boundary of each pixel 50, an inter-pixel isolation section 121 is formed, penetrating the semiconductor substrate 101 and separating the photodiode PD on a pixel-by-pixel basis. The inter-pixel isolation section 121 is constructed by embedding a fixed charge film 122, an insulating film 123, and an air gap (air layer) 124 in a trench formed by excavating in the depth direction from the second surface SA side of the semiconductor substrate 101. The insulating film 123 is formed inside the fixed charge film 122 formed on the side and bottom of the trench, and the air gap 124 is formed in the central part inside the insulating film 123. An element isolation section STI 125 is formed on the first surface FA side of the semiconductor substrate 101 of the inter-pixel isolation section 121. For the material of the fixed charge film 122, for example, hafnium oxide (HfO2), zirconium dioxide (ZrO2), tantalum oxide (Ta2O5), etc. can be used. For the material of the insulating film 123, for example, SiO2, or a composite material mainly composed of SiO2 (SiON, SiOC, etc.) can be used. Inside the insulating film 123, instead of an air gap 124, a metallic material such as polysilicon, tungsten (W), aluminum (Al), or copper (Cu) may be embedded. Alternatively, the air gap 124 may not be formed at all, and the insulating film 123, polysilicon, or metallic material may be used for filling. The fixed charge film 122 of the inter-pixel separation portion 121 is formed simultaneously with the fixed charge film 103 formed on the light incident surface side of the semiconductor substrate 101, and is therefore connected to the fixed charge film 103. Similarly, the insulating film 123 is connected to the insulating film 104 formed on the light incident surface side of the semiconductor substrate 101 for the same reason.

[0051] On the light incident surface of each pixel 50, a surface with irregularities 127 is formed, in which fine recesses 126 are arranged periodically. The surface with irregularities 127 is also called a moth-eye structure. In the example in Figure 4, the recesses 126 are formed in the shape of an inverted pyramid, which is a square pyramid formed facing downwards, but the shape of the recesses 126 is not limited to a square pyramid; it may also be a rectangular or trapezoidal shape in cross-section. The surface with irregularities 127 can also be described as a structure in which the protrusions formed by the recesses 126 are arranged periodically. The surface with irregularities 127 produces an anti-reflective effect by gradually reducing the refractive index difference on the light incident surface of the semiconductor substrate 101.

[0052] An inter-pixel light-shielding film 106 is formed on the light incident surface of the semiconductor substrate 101 on which the inter-pixel separation portion 121 is formed. The inter-pixel light-shielding film 106 is composed of a single layer or multiple layers of metal film. The inter-pixel light-shielding film 106 can be made of any material that blocks light, but it is preferable to form it of a metal film such as aluminum (Al), tungsten (W), or copper (Cu) as a material that has strong light-shielding properties and can be processed with high precision by microfabrication, such as etching. In addition, it can be made of silver (Ag), gold (Au), platinum (Pt), molybdenum (Mo), chromium (Cr), titanium (Ti), nickel (Ni), iron (Fe), and tellurium (Te), or alloys containing these metals. Furthermore, a barrier metal may be formed in the lower layer of the inter-pixel light-shielding film 106 to improve adhesion to the substrate. The barrier metal material can be, for example, titanium (Ti), tantalum (Ta), tungsten (W), cobalt (Co), molybdenum (Mo), or alloys, nitrides, oxides, or carbides thereof.

[0053] A planarization film 107 is formed above the interpixel light-shielding film 106 and the uneven parts 127 so as to fill in any steps such as those in the interpixel light-shielding film 106 and the uneven parts 127. A color filter layer 105 is arranged above the planarization film 107, formed by rotary coating a photosensitive resin containing a pigment such as a pigment or dye. For example, an organic material such as resin or an inorganic film such as SiO2 can be used as the material for the planarization film 107. The color filter layer 105 consists of a red filter 131R that transmits the red wavelength region, a green filter 131G that transmits the green wavelength region, and a blue filter 131B that transmits the blue wavelength region, arranged, for example, in a Bayer array, but other arrangement methods may also be used. The green filter 131G is thinner than the red filter 131R and the blue filter 131B in order to improve sensitivity.

[0054] An on-chip lens 108 is formed on the upper side of the color filter layer 105, for each pixel. The on-chip lens 108 is made of a resin-based material such as styrene resin, acrylic resin, styrene-acrylic copolymer resin, or siloxane resin. It can also be constructed by dispersing titanium oxide particles in the above-mentioned organic material or polyimide resin. Alternatively, it may be made of an inorganic material such as silicon nitride (SiN) or silicon oxynitride (SiON). The on-chip lens 108 focuses the incident light, and the focused light is efficiently incident on the photodiode PD via the color filter layer 105.

[0055] An anti-reflective coating 109 made of a material having a different refractive index than the on-chip lens 108 is formed on the surface of the on-chip lens 108. The thickness d of this anti-reflective coating 109 is preferably approximately d = λ / (4n), where n is its refractive index and λ is the average assumed wavelength.

[0056] As shown in Figure 4, the wiring layer 102 formed on the first surface FA side of the semiconductor substrate 101 is constructed by stacking multiple layers of metal wiring 151 and interlayer insulating films SiO2 152 and SiN 153. In Figure 4, x in metal wiring 151-x indicates that the metal wiring 151 is the x-th metal wiring 151 from the semiconductor substrate 101 side. For example, metal wiring 151-1 is the first metal wiring 151 from the semiconductor substrate 101 side within the wiring layer 102. In the example in Figure 4, an example with four layers of metal wiring 151 is shown, but the number of layers of metal wiring 151 may be multiple other than four, or it may be just one layer. The metal wiring 151 is formed from a metal film of a metallic material such as Al, Ag, Au, Cu, Pt, Mo, Cr, Ti, Ni, W, Fe, or an alloy material containing these metals. Each layer's metal wiring 151 is connected at predetermined locations to other metal wirings 151 in the layers above and below it by via plugs, for example, made of W or Cu. The interlayer insulating film may be an insulating film other than the SiO2 film 152 and SiN 153, such as a Low-k film (low dielectric constant insulating film). Multiple pixel transistors Tr, such as transfer transistors TG that read out the charge accumulated in the photodiode PD, are formed on the wiring layer 102.

[0057] In each pixel 50 of the first configuration example configured as described above, the number of recesses 126 in the uneven portion 127 formed on the light incident surface of the semiconductor substrate 101 differs between the pixel 50 where the green filter 131G is placed (hereinafter referred to as G pixel 50G), and the other pixels 50 where the blue filter 131B is placed (hereinafter referred to as B pixel 50B) and the pixel 50 where the red filter 131R is placed (hereinafter referred to as R pixel 50R).

[0058] Figure 5 is a plan view showing the arrangement of the color filter layer 105 and the uneven portion 127 for each of the 2x2 pixels 50.

[0059] The color filter layer 105 has a 2x2 arrangement of four pixels, with a red filter 131R, a blue filter 131B, and two green filters 131G arranged in a Bayer array. Therefore, in the same row of the pixel array 41, there will be either a GB pixel row with alternating G pixels 50G and B pixels 50B, or a GR pixel row with alternating R pixels 50R and G pixels 50G. In Figure 4, however, to explain all pixel structures, the G pixels 50G, B pixels 50B, and R pixels 50R are shown side by side.

[0060] As shown in Figure 5, in the first configuration example of the pixel 50, the number of recesses 126 differs between the G pixel 50G, the B pixel 50B, and the R pixel 50R. Specifically, the G pixel 50G has nine recesses 126 arranged in a 3x3 configuration, while the R pixel 50R and B pixel 50B have four recesses 126 arranged in a 2x2 configuration. The planar size of the recesses 126, in other words, the pitch of the recesses 126, is the same for the G pixel 50G, the B pixel 50B, and the R pixel 50R.

[0061] Figure 6 shows the sensitivity characteristics of each color filter: red filter 131R, blue filter 131B, and green filter 131G.

[0062] While the inter-pixel separation unit 121 increases the color mixing suppression effect, this increased suppression effect can make the influence of the physical characteristics of the color filter layer 105 more apparent. For example, if the sensitivity characteristics of the color filter layer 105 are as shown in Figure 6, the green filter 131G has lower sensitivity in the infrared region 171 enclosed by the dashed line compared to the red filter 131R and the blue filter 131B. Thus, because the refractive index characteristics and transmittance of each color filter—red filter 131R, blue filter 131B, and green filter 131G—differ, differences in sensitivity can occur in the infrared region, which is commonly received by each pixel 50.

[0063] In the first configuration example, the number of recesses 126 in the G pixel 50G is greater than that in the R pixel 50R and B pixel 50B. As a result, the G pixel 50G can suppress the reflection of incident light on the second surface SA, which is the light incident surface of the semiconductor substrate 101, more than the R pixel 50R and B pixel 50B. The amount of light taken into the photodiode PD and converted into photoelectric light in the G pixel 50G can be increased compared to the R pixel 50R and B pixel 50B. Therefore, the difference in sensitivity in the infrared region, which is commonly received by each pixel 50 with different colors in the color filter layer 105, can be suppressed. The pitch of the fine recesses 126 is determined by the wavelength of the light received by the photodiode PD. For example, if it is desired to detect more light in the infrared region with the photodiode PD, the pitch of the recesses 126 and the depth of the recesses should be appropriately determined according to the wavelength in the infrared region.

[0064] The above example shows an arrangement of the recesses 127 when the sensitivity of the green filter 131G is lower than that of the red filter 131R and the blue filter 131B, as in the sensitivity characteristics shown in Figure 6. Of the red filter 131R, blue filter 131B, and green filter 131G, for example, if the sensitivity of the red filter 131R is lower than that of the others, more recesses 126 are arranged for the R pixels 50R, and if the sensitivity of the blue filter 131B is lower than that of the others, more recesses 126 are arranged for the B pixels 50B.

[0065] <5. Second Pixel Configuration Example> Figure 7 is a cross-sectional view showing a second configuration example of the pixel 50. Figure 8 is a plan view corresponding to Figure 5 of the first configuration example, and is a plan view showing the arrangement of the color filter layer 105 and the uneven portion 127 of the second configuration example.

[0066] Figure 7 is similar to the first configuration example shown in Figure 4 in that it shows three pixels 50 having R, G, and B color filters arranged side by side.

[0067] In the explanations of the second configuration example and subsequent examples in Figure 7, the same reference numerals are used for parts common to the configuration examples described up to that point, and explanations are omitted as appropriate.

[0068] In the first example of the pixel configuration described in Figures 4 and 5, the number of recesses 126 in the uneven portion 127 provided in each pixel 50 was configured differently for the G pixel 50G, the B pixel 50B, and the R pixel 50R. Specifically, the G pixel 50G had nine recesses 126 arranged in a 3x3 configuration, while the R pixel 50R and B pixel 50B had four recesses 126 arranged in a 2x2 configuration.

[0069] In contrast, in the second configuration example shown in Figures 7 and 8, the number of recesses 126 in the uneven portion 127 is the same for all G pixels 50G, B pixels 50B, and R pixels 50R. Four recesses 126 are arranged in a 2x2 array for each pixel 50. However, the depth of the recesses 126 when viewed in cross-section and the pitch (planar size) when viewed in plan are different for the G pixels 50G, B pixels 50B, and R pixels 50R. More specifically, the pitch and depth of the recesses 126 in the G pixels 50G are larger than those of the recesses 126 in the B pixels 50B and R pixels 50R. As a result, the G pixels 50G can capture more infrared light into the photodiode PD in the semiconductor substrate 101 than the B pixels 50B and R pixels 50R, and convert it into photoelectric light. Therefore, it is possible to suppress the difference in sensitivity in the infrared region that is commonly received by each pixel 50, which has a different color in the color filter layer 105.

[0070] <Modification> The first and second configurations described above are configured such that the number, pitch, or depth of the recesses 126 of the uneven portion 127 provided in each pixel 50 is different for the G pixel 50G and the B pixel 50B and R pixel 50R, thereby enabling more infrared light to be taken into the semiconductor substrate 101 in the G pixel 50G than in the B pixel 50B and R pixel 50R, and suppressing the difference in sensitivity in the infrared region.

[0071] The configuration of the recessed portion 127 can be made different between the G pixel 50G and the B pixel 50B and R pixel 50R. For example, the G pixel 50G may have multiple recesses 126 arranged in a 2x2 or 3x3 configuration, while the B pixel 50B and R pixel 50R may not have any recessed portions 127, i.e., none of the recesses 126, thereby suppressing the difference in sensitivity in the infrared region. The difference in the number of recesses 126 includes the presence or absence of recesses 126.

[0072] Furthermore, in the first and second configuration examples described above, the configuration of the uneven portion 127 of the B pixel 50B and the R pixel 50R was made the same. However, the configuration of the uneven portion 127 of the B pixel 50B and the R pixel 50R may also be made different depending on the sensitivity characteristics. For example, as shown in Figure 9, for the G pixel 50G, four recesses 126 may be arranged in a 2x2 array, for the R pixel 50R, one recess 126 may be provided, and for the B pixel 50B, no recesses 126 may be provided, thereby suppressing the difference in sensitivity in the infrared region.

[0073] <6. Third Pixel Configuration Example> Figure 10 is a cross-sectional view showing a third configuration example of pixel 50.

[0074] In Figure 10, parts common to the first configuration example shown in Figure 4 are denoted by the same reference numerals, and explanations are omitted as appropriate.

[0075] Comparing the third configuration example in Figure 10 with the first configuration example in Figure 4, the pixel separation section 121 in the first configuration example has been changed to a pixel separation section 121'. In the first configuration example, the pixel separation section 121 penetrated the semiconductor substrate 101 from the second surface SA to the first surface FA, completely separating the photodiodes PD on a pixel-by-pixel basis. In contrast, the pixel separation section 121' in the third configuration example does not penetrate the semiconductor substrate 101, but instead has a P-type semiconductor region 111 on the first surface FA side of the semiconductor substrate 101. In other words, the difference between the pixel separation section 121 of the first configuration example and the pixel separation section 121' of the third configuration example is the difference in the depth of the trench formed by excavating to a predetermined depth from the second surface SA side of the semiconductor substrate 101. The depth of the trench when leaving a P-type semiconductor region 111 in a part of the depth direction of the semiconductor substrate 101 can be set arbitrarily.

[0076] If the photodiode PD is not completely separated on a pixel-by-pixel basis by the inter-pixel separation section 121', the sensitivity difference in the infrared region will be smaller than when the photodiode PD is completely separated. By suppressing the sensitivity difference between pixels of different colors with the inter-pixel separation section 121' that does not completely separate the pixels, and by providing differences in the configuration of the uneven sections 127, the sensitivity difference between pixels of different colors can be further suppressed. Therefore, even in the third configuration example, the sensitivity difference in the infrared region, which is commonly received by each pixel 50 with different colors in the color filter layer 105, can be suppressed.

[0077] <7. Fourth Pixel Configuration Example> Figure 11 is a cross-sectional view showing a fourth configuration example of the pixel 50. Figure 12 is a plan view showing the arrangement of the color filter layer 105 and the uneven portion 127 in the fourth configuration example.

[0078] The fourth configuration example shown in Figures 11 and 12 differs from the first configuration example in the configuration of the color filter layer 105 and the on-chip lens 108.

[0079] Specifically, in the first configuration example, the color filter layer 105 had a red filter 131R, a green filter 131G, and a blue filter 131B arranged in a Bayer array. In contrast, the fourth configuration example is an example in which multiple pixels 50 are used as the same-color arrangement unit and R, G, and B color filters are arranged in a Bayer array. That is, in the examples of Figures 11 and 12, four pixels in a 2x2 arrangement are used as the same-color arrangement unit and the red filter 131R, green filter 131G, blue filter 131B, and green filter 131G are arranged in a Bayer array. Such a color filter array is called a quad Bayer array.

[0080] In the first configuration example, the on-chip lenses 108 were arranged in units of one pixel. In contrast, in the fourth configuration example, one on-chip lens 108 is arranged in units of four pixels, which are 2x2 units of the same color.

[0081] The number of recesses 126 in the uneven portion 127, the planar size (pitch), or the depth are configured differently for the G pixel 50G and the B pixels 50B and R pixels 50R, and the G pixel 50G is configured to capture more infrared light into the photodiode PD in the semiconductor substrate 101 than the B pixels 50B and R pixels 50R, similar to the first or second configuration example described above. Figures 11 and 12 show an example in which the number of recesses 126 differs between the G pixel 50G and the B pixels 50B and R pixels 50R, similar to the first configuration example.

[0082] In the fourth configuration example, as the circuit configuration for the pixels 50, for example, a photodiode PD and a transfer transistor TG may be provided for each pixel 50, and the readout circuit may be shared by four pixels, which are the same color units of the color filter layer 105 and the on-chip lens units 108.

[0083] In this case, the photodetector 13 can operate in a mode in which it simultaneously turns on the transfer transistors TG of the four pixels of a shared unit and outputs a pixel signal to the column processing unit 43, which is the sum of the signal charges generated by the four photodiodes PD of the four pixels.

[0084] For example, the photodetector 13 can operate in a mode in which it simultaneously turns on transfer transistors TG in units of two pixels that are arranged vertically or horizontally among the four pixels of a shared unit, and outputs a pixel signal to the column processing unit 43 by summing the signal charges generated by the two photodiodes PD of the two pixels.

[0085] For example, the light detection device 13 can operate in a mode in which it turns on the transfer transistor TG for each of the four shared pixels one by one, and outputs a pixel signal for each pixel to the column processing unit 43. In the two-pixel or one-pixel operation mode, the output pixel signal can be used as the signal for the captured image or as the signal for phase difference detection.

[0086] <8. Fifth Pixel Configuration Example> Figure 13 is a cross-sectional view showing a fifth configuration example of pixel 50.

[0087] The fifth configuration example in Figure 13 is a configuration in which the on-chip lens 108 is modified from the first configuration example shown in Figure 4. In the first configuration example shown in Figure 4, the shape of the on-chip lens 108 was the same for each pixel 50, but in the fifth configuration example in Figure 13, the shape of the on-chip lens 108 of the G pixel 50G is different from that of the B pixel 50B and R pixel 50R. Specifically, the curvature of the on-chip lens 108 of the G pixel 50G is formed to be greater than that of the on-chip lens 108 of the B pixel 50B and R pixel 50R. By forming a larger curvature of the on-chip lens 108, light in the long-wavelength infrared region is refracted, and more light can be captured than in the B pixel 50B and R pixel 50R. By changing not only the uneven portion 127 but also the shape of the on-chip lens 108, the sensitivity in the infrared region of the G pixel 50G can be improved compared to the B pixel 50B and R pixel 50R, and the difference in sensitivity in the infrared region can be suppressed.

[0088] The configuration of the on-chip lens 108 in the fifth configuration example in Figure 13 can also be combined with the other configuration examples described above. In the fifth configuration example shown in Figure 13, a configuration with a different curvature of the on-chip lens 108 is combined with the first configuration example in Figure 4, which has a different number of recesses 126. However, it may also be combined with the second configuration example in Figure 7, which has different pitch and depth of recesses 126. It may also be combined with the third configuration example in Figure 10, or the fourth configuration examples in Figures 11 and 12.

[0089] <9. Sixth Pixel Configuration Example> Figure 14 is a cross-sectional view showing the sixth configuration example of pixel 50.

[0090] The sixth configuration example in Figure 14 is basically the same as the first configuration example shown in Figure 4 in terms of the configuration of the semiconductor substrate 101, the uneven portion 127 on the light incident surface side of the semiconductor substrate 101, the color filter layer 105, the on-chip lens 108, etc. However, the configuration of the uneven portion 127 is the same for the G pixel 50G, B pixel 50B, and R pixel 50R, which is different from the first configuration example in Figure 4. In addition, the sixth configuration example in Figure 14 differs from the first configuration example shown in Figure 4 in the configuration of the wiring layer 102 formed on the first surface FA side of the semiconductor substrate 101.

[0091] In the sixth configuration example, the wiring layer 102 consists of six layers of metal wiring 151, comprising metal wirings 151-1 to 151-6, with an interlayer insulating film of SiO2 film 152 and SiN 153 between them. In addition, multiple MIM (Metal-Insulator-Metal) capacitive elements 201 are formed between the second metal wiring 151-2 and the third metal wiring 151-3. The MIM capacitive element 201 consists of a planar electrode portion 211 extending in a direction parallel to the metal wiring 151 and a vertical electrode portion 212 extending in a direction perpendicular to the metal wiring 151. The entire planar electrode portion 211 and vertical electrode portion 212 have a structure in which an insulator is sandwiched between two metal wirings (electrodes). The vertical electrode portion 212 is electrically connected to the metal wiring 151-2 on the semiconductor substrate 101 side, and the planar electrode portion 211 is electrically connected to the metal wiring 151-3 on the lower layer side. The MIM capacitive elements 201 are arranged for every 50 pixels as additional capacitances (SubFD) as shown in the circuit configuration of Figure 3.

[0092] Figure 15 is a plan view showing the arrangement of the planar electrode portions 211 of the MIM capacitive elements 201 for each pixel 50. In Figure 15, the regions of the red filter 131R, blue filter 131B, and two green filters 131G of the color filter layer 105 arranged in a Bayer array correspond to the pixel regions of each pixel 50.

[0093] The planar electrode portion 211 of the MIM capacitive element 201 is positioned approximately in the center of the pixel area for the G pixel 50G, and for the B pixel 50B and R pixel 50R, it is positioned close to the adjacent G pixel 50G in the row direction. In the example in Figure 15, a portion of the planar electrode portion 211 of the B pixel 50B and R pixel 50R is positioned close to the G pixel 50G so that it enters the pixel area of ​​the adjacent G pixel 50G. The position of the planar electrode portion 211 may be shifted to the pixel area of ​​the adjacent G pixel 50G, or it may be positioned close to the adjacent G pixel 50G within the area of ​​the own pixel.

[0094] Figure 16 is a diagram illustrating the effect of the arrangement of the MIM capacitive elements 201 shown in Figure 15.

[0095] Long-wavelength infrared light incident from the first surface FA side of the semiconductor substrate 101, which is the light incident surface, is absorbed little by the silicon semiconductor substrate 101 and easily penetrates the semiconductor substrate 101. Light that penetrates the semiconductor substrate 101 and is incident on the wiring layer 102 is reflected by the MIM capacitive element 201 located in the lower layer of the photodiode PD and returned to the semiconductor substrate 101. The MIM capacitive element 201 is an example of a reflective structure that reflects light that penetrates the semiconductor substrate 101 and is incident on the wiring layer 102 back to the semiconductor substrate 101. The MIM capacitive element 201 of the G pixel 50G is located approximately in the center of the pixel area, so it returns the infrared light that has penetrated the semiconductor substrate 101 to the photoelectric conversion area of ​​the pixel itself. Since the MIM capacitive elements 201 of the B pixel 50B and R pixel 50R are positioned close to the G pixel 50G, some of the infrared light that has penetrated the semiconductor substrate 101 is returned to the photoelectric conversion region of the pixel itself, and the remaining portion is returned to the photoelectric conversion region of the G pixel 50G. Therefore, the amount of infrared light that has penetrated the semiconductor substrate 101 that is reflected by the MIM capacitive elements 201 and recaptured can be made greater in the G pixel 50G than in the B pixel 50B and R pixel 50R. According to the sixth configuration example, by devising the arrangement of the MIM capacitive elements 201 within the pixel, the difference in sensitivity in the infrared region between pixels of different colors can be suppressed.

[0096] In the example shown in Figure 14, the MIM capacitive element 201 was placed between the second metal wiring 151-2 and the third metal wiring 151-3, but the placement of the MIM capacitive element 201 in any layer is arbitrary. However, it is preferable to place the MIM capacitive element 201 in a layer close to the semiconductor substrate 101 in order to reflect infrared light that has penetrated the semiconductor substrate 101.

[0097] Instead of the MIM capacitance element 201, for example, a comb-shaped wiring capacitance or a PIP (Poly silicon-Insulator-Poly silicon) capacitance element may be provided.

[0098] <Modified Example> Figure 17 is a modified example of the sixth configuration described in Figures 14 to 16, and is a plan view showing a modified arrangement of the planar electrode portion 211 of the MIM capacitance element 201.

[0099] In the sixth configuration example described above, as explained with reference to Figure 15, the arrangement of the MIM capacitive elements 201 within the pixels was different for the G pixel 50G and the B pixels 50B and R pixels 50R. Specifically, the planar electrode portion 211 was positioned approximately in the center of the pixel area in the G pixel 50G, and in the B pixels 50B and R pixels 50R, which are different color pixels adjacent to the G pixel 50G, it was positioned close to the adjacent G pixel 50G in the row direction. This ensured that infrared light that had penetrated the semiconductor substrate 101 in the B pixel 50B or R pixel 50R entered the pixel area of ​​the G pixel 50G.

[0100] Figures 17A and 17B show other configuration examples in which infrared light that has penetrated the semiconductor substrate 101 in the B pixel 50B or R pixel 50R enters the pixel area of ​​the G pixel 50G.

[0101] Figure 17A is a plan view of the planar electrode portion 211 of the MIM capacitance element 201, showing a first modified example of the sixth configuration.

[0102] In the first modification of the sixth configuration example, the planar electrode portion 211 of the G pixel 50G is formed to have a larger planar area than the planar electrode portions 211 of the B pixel 50B and the R pixel 50R. This allows the G pixel 50G to return a larger amount of infrared light that has penetrated the semiconductor substrate 101 to its own pixel's photoelectric conversion region than the B pixel 50B and the R pixel 50R. In the first modification of the sixth configuration example, by making the area of ​​the planar electrode portion 211 different, the difference in sensitivity in the infrared region between different colored pixels can be suppressed. The arrangement of the MIM capacitive elements 201 within the pixel as described in Figure 15 may be combined with the difference in the planar area of ​​the MIM capacitive elements 201 in the first modification example.

[0103] Figure 17B is a plan view of the planar electrode portion 211 of the MIM capacitance element 201, showing a second modified example of the sixth configuration.

[0104] In the second modification of the sixth configuration example, the presence or absence of the MIM capacitive element 201 differs between the G pixel 50G and the B pixel 50B and R pixel 50R. Specifically, the G pixel 50G is provided with the MIM capacitive element 201, while the B pixel 50B and R pixel 50R are not. This allows the G pixel 50G to return a larger amount of infrared light that has penetrated the semiconductor substrate 101 to its own pixel's photoelectric conversion region than the B pixel 50B and R pixel 50R. In the second modification of the sixth configuration example, the presence or absence of the MIM capacitive element 201 can also be differed to suppress the difference in sensitivity in the infrared region between pixels of different colors. In the B pixel 50B and R pixel 50R, which do not have the MIM capacitive element 201, the capacitance for accumulating signal charge is reduced, but this is effective when it is more important to suppress the difference in sensitivity in the infrared region between pixels of different colors.

[0105] The sixth configuration example in Figure 14 can also be combined with the other configuration examples described above. For example, in the sixth configuration example in Figure 14, the configuration of the uneven portion 127 is the same for the G pixel 50G, B pixel 50B, and R pixel 50R, but the number of recesses 126 of the uneven portion 127, the planar size (pitch), or the depth may be different for the G pixel 50G and the B pixel 50B and R pixel 50R. Alternatively, the shape of the on-chip lens 108 of the G pixel 50G may be different from that of the B pixel 50B and R pixel 50R.

[0106] <10. Seventh Pixel Configuration Example> Figure 18 is a cross-sectional view showing the seventh configuration example of pixel 50.

[0107] In the seventh configuration example shown in Figure 18, the configuration of the semiconductor substrate 101 and the configuration on the light incident surface side of the semiconductor substrate 101 are the same as in the sixth configuration example shown in Figure 14. In the seventh configuration example in Figure 18, the configuration of the wiring layer 102 formed on the first surface FA side of the semiconductor substrate 101 differs from that of the sixth configuration example shown in Figure 14.

[0108] In the seventh configuration example, the wiring layer 102 consists of six layers of metal wiring 151, comprising metal wirings 151-1 to 151-6, with an interlayer insulating film of SiO2 film 152 and SiN 153 between them. Furthermore, a reflective film 202 is formed only in the pixel region of the G pixel 50G, on the same layer as the second metal wiring 151-2. The reflective film 202 is not formed in the B pixel 50B and the R pixel 50R, and metal wiring 151-2 is formed therein.

[0109] The reflective film 202 has the function of reflecting light that has penetrated the semiconductor substrate 101 and been incident on the wiring layer 102, and returning it to the semiconductor substrate 101. The reflective film 202 is another example of a reflective structure that can replace the MIM capacitive element 201. The pixel 50 may have both the MIM capacitive element 201 and the reflective film 202. The reflective film 202 is not provided for the B pixel 50B and the R pixel 50R, but is provided only for the G pixel 50G, so that the amount of infrared light that has penetrated the semiconductor substrate 101 reflected by the G pixel 50G can be made greater than that of the B pixel 50B and the R pixel 50R. According to the seventh configuration example, by making the presence or absence of the reflective film 202 different between the G pixel 50G and the B pixel 50B and R pixel 50R, the difference in sensitivity in the infrared region between different colored pixels can be suppressed. In this configuration, a reflective film 202 is provided on each pixel 50, and the area of ​​the reflective film 202 may be different for the G pixel 50G, the B pixel 50B, and the R pixel 50R. That is, the planar area of ​​the reflective film 202 for the G pixel 50G may be increased, and the planar area of ​​the reflective film 202 for the B pixel 50B and the R pixel 50R may be made smaller than that of the G pixel 50G, thereby suppressing the difference in sensitivity in the infrared region between pixels of different colors.

[0110] The reflective film 202 may be an isolated pattern and not electrically connected to other metal wirings 151, or it may be electrically connected to other metal wirings 151 and a predetermined voltage, such as ground, may be applied to it.

[0111] <11. Eighth Pixel Configuration Example> In the first to seventh configuration examples described above, an example was given in which the pixel 50 is constructed using a single semiconductor substrate 101. However, the pixel 50 may also be constructed using a stacked structure in which multiple semiconductor substrates are stacked. For example, when the pixel 50 is constructed using a stacked structure of two semiconductor substrates, the wiring layer of the other semiconductor substrate is bonded to the wiring layer 102 of the semiconductor substrate 101. Alternatively, for example, the pixel 50 may be constructed using a stacked structure of three semiconductor substrates.

[0112] Figure 19 is a cross-sectional view showing an eighth example of the pixel configuration of 50, and is a cross-sectional view showing an example of the pixel configuration when the pixel 50 is made up of a stacked structure of three semiconductor substrates.

[0113] The pixel 50 according to the eighth configuration example is constructed by stacking a first substrate 221, a second substrate 222, and a third substrate 223 in order from the light incident surface side on which the on-chip lens 108 is formed.

[0114] The first substrate 221 is composed of a semiconductor substrate 101, which is the first semiconductor substrate, and a wiring layer 102, which is the first wiring layer. The configuration of the first substrate 221 on the light incident surface side from the semiconductor substrate 101 is the same as the fourth configuration example shown in Figure 11, and the arrangement units of the same color of the color filter layer 105 and the arrangement units of the on-chip lens 108 are configured as 2x2 4-pixel units. The wiring layer 102 of the first substrate 221 has the MIM capacitive element 201 described in the sixth configuration example in Figure 14 between metal wiring 151-1 and metal wiring 151-2.

[0115] On the first surface FA side of the semiconductor substrate 101, a transfer transistor TG and an N-type semiconductor region 231 constituting a floating diffusion FD are formed for each pixel. Each N-type semiconductor region 231 of the four pixels sharing one on-chip lens 108 is electrically connected to each other via a pad portion 232 formed on the first surface FA of the semiconductor substrate 101. As a result, the floating diffusion FD is shared by the four pixels sharing one on-chip lens 108. The pad portion 232 is connected to the wiring layer 252 of the second substrate 222 via a through-electrode 233 that penetrates the semiconductor substrate 251 of the second substrate 222. The pad portion 232 is made of, for example, polysilicon (Poly Si), more specifically, doped polysilicon with impurities added. The pad portion 232 may also be made of a high-melting-point metallic material such as tungsten (W), titanium (Ti), molybdenum (Mo), or tantalum (Ta).

[0116] The second substrate 222 has a semiconductor substrate 251, a wiring layer 252, and an insulating layer 253. The third substrate 223 has a semiconductor substrate 271 and a wiring layer 272.

[0117] On the second substrate 222, an insulating layer 253 is formed on the back side of the semiconductor substrate 251, which is the second semiconductor substrate, and a wiring layer 252, which is the second wiring layer, is formed on the front side of the semiconductor substrate 251. The insulating layer 253 formed on the back side of the semiconductor substrate 251 is bonded to the wiring layer 102 of the first substrate 221, and the wiring layer 252 formed on the front side of the semiconductor substrate 251 is bonded to the wiring layer 272 of the third substrate 223.

[0118] Multiple pixel transistors Tr2, used by a shared unit of four pixels, are formed on the second substrate 222. Each pixel transistor Tr2 is either a reset transistor RST, a switching transistor FDG, an amplification transistor AMP, or a selection transistor SEL. For example, a through electrode 233 connected to a floating diffusion FD is electrically connected to the gate of the amplification transistor AMP and the source of the switching transistor FDG.

[0119] The wiring layer 252 of the second substrate 222 has multiple layers of metal wiring 281 and an interlayer insulating film 282. In Figure 19, three layers of metal wiring 281 are formed, but the number of layers of metal wiring 281 is not limited. The metal wiring 281 is made of, for example, tungsten (W), aluminum (Al), and copper (Cu). The interlayer insulating film 282 is made of, for example, silicon oxide. The wiring layer 252 further has multiple bonding electrodes 283 at the bonding surface with the wiring layer 272 of the third substrate 223. The bonding electrodes 283 are made of, for example, a metallic material such as Cu (copper) or Al (aluminum). Each bonding electrode 283 is used for electrical connection between the second substrate 222 and the third substrate 223 and for bonding the second substrate 222 and the third substrate 223.

[0120] The third substrate 223 has a semiconductor substrate 271, which is a third semiconductor substrate, and a wiring layer 272, which is a third wiring layer, and is bonded to the second substrate 222 with the front surface of the semiconductor substrate 271 facing the front surface of the second substrate 222. In other words, the third substrate 223 is bonded to the second substrate 222 face to face. Multiple transistors Tr3, which are part of the signal processing unit 46, are formed on the semiconductor substrate 271.

[0121] The wiring layer 272 has multiple layers of metal wiring 291 and an interlayer insulating film 292. In Figure 19, two layers of metal wiring 291 are formed, but the number of layers of metal wiring 291 is not limited. The metal wiring 291 is made of, for example, tungsten (W), aluminum (Al), and copper (Cu). The interlayer insulating film 292 is made of, for example, silicon oxide. The wiring layer 272 further has multiple bonding electrodes 293 at the bonding surface with the wiring layer 252 of the second substrate 222. The bonding electrodes 293 are made of, for example, a metallic material such as Cu (copper) or Al (aluminum). Each bonding electrode 293 is used for electrical connection between the second substrate 222 and the third substrate 223 and for bonding the second substrate 222 and the third substrate 223.

[0122] As described above, according to the eighth configuration example, by stacking three semiconductor substrates, the photodetector 13 can be formed with the same chip size as before, even when the number of pixels or pixel circuits is increased. Alternatively, in the case of the same number of pixels or pixel circuits as before, a photodetector 13 with an even smaller chip size can be provided.

[0123] In the eighth configuration example, in which the pixel 50 is constructed using a stacked structure of three semiconductor substrates, the difference in sensitivity in the infrared region between pixels of different colors can be suppressed by varying the unevenness 127 and the MIM capacitive elements 201. The MIM capacitive elements 201 are placed between the semiconductor substrate 101 of the first substrate 221 and the semiconductor substrate 251 of the second substrate 222. For example, even when the pixel 50 is constructed using a stacked structure of two semiconductor substrates, the MIM capacitive elements are placed between the semiconductor substrate 101 of the first substrate 221 and the semiconductor substrate 251 of the second substrate 222.

[0124] In the eighth configuration example shown in Figure 19, the first configuration example, which differs the number of recesses 126 in the uneven portion 127, and the sixth configuration example, which differs the arrangement and planar area of ​​the MIM capacitive elements 201, are adopted as configurations to suppress the sensitivity difference in the infrared region between different colored pixels. However, it goes without saying that other configurations described above may also be adopted. For example, the planar size (pitch) and depth of the recesses 126 adopted in the second configuration example, and the reflective film 202 adopted in the seventh configuration example, may be made different for the G pixel 50G, the B pixel 50B, and the R pixel 50R to suppress the sensitivity difference in the infrared region between different colored pixels.

[0125] <12. Summary of Configuration Examples 1 to 8> The pixels 50 in Configuration Examples 1 to 8 each have a photodiode PD, which is a photoelectric conversion unit formed on a semiconductor substrate 101, and a color filter layer 105 on the light incident surface side of the semiconductor substrate 101, in which predetermined color filters are arranged in a predetermined arrangement such as a Bayer array.

[0126] The color filter layer 105 allows light in a first wavelength region, which differs for each color of the color filter layer 105, and light in a second wavelength region, which is common to all pixels, to pass through and be incident on the photodiode PD. The light in the first wavelength region is visible light of R, G, or B, and each pixel 50 receives different light of R, G, or B depending on whether the color filter layer 105 placed in each pixel 50 is a red filter 131R, a green filter 131G, or a blue filter 131B. On the other hand, the light in the second wavelength region is infrared light, and since the color filter layer 105 placed in each pixel 50 allows infrared light to pass through, each pixel 50 receives infrared light in common.

[0127] In the pixel 50, at least one of the number of recesses 126 in the uneven portion 127, the pitch (planar size), or the depth is configured differently for the pixel 50 of the first color filter of the color filter layer 105 and for the pixel 50 of the second color filter. As shown in Figure 6, if the physical characteristics of the color filters of the color filter layer 105 are such that the green filter 131G has lower sensitivity in the infrared region compared to the red filter 131R and the blue filter 131B, then, as in the first to eighth configuration examples described above, the number of recesses 126 in the uneven portion 127 provided in each pixel 50, the pitch (planar size), or the depth are configured differently for the G pixel 50G and the B pixel 50B and R pixel 50R, so that the G pixel 50G captures more infrared light into the semiconductor substrate 101 than the B pixel 50B and R pixel 50R. This makes it possible to suppress the sensitivity difference between different colored pixels in the infrared region.

[0128] If the physical characteristics of the color filter in the color filter layer 105 differ from those shown in Figure 6, for example, if the sensitivity in the infrared region is lower for the blue filter 131B than for the red filter 131R and the green filter 131G, the photodetector 13 will have different configurations for the number, pitch (planar size), or depth of the recesses 126 for the B pixel 50B and the R pixel 50R and G pixel 50G. For example, the photodetector 13 will have a configuration in which the number of recesses 126 in the B pixel 50B is greater than that in the R pixel 50R and G pixel 50G, or the pitch (planar size) or depth of the recesses 126 is increased. For example, if the infrared sensitivity of the R pixel 50R is lower than that of the G pixel 50G and B pixel 50B, the photodetector 13 may configure the R pixel 50R to have more recesses 126 than the G pixel 50G and B pixel 50B, or to have a larger pitch (planar size) or depth of the recesses 126 than the G pixel 50G and B pixel 50B.

[0129] The first to eighth configuration examples described above describe cases in which a red filter 131R, a green filter 131G, and a blue filter 131B are arranged as the color filters of the color filter layer 105.

[0130] The color filter arrangement of the color filter layer 105 is not limited to R, G, and B; other color arrangements are also possible. For example, an arrangement in which 2x2 four-pixel color filters are repeatedly placed in the row and column directions as complementary colors of yellow (Y), cyan (C), green (G), and magenta (M). In this case as well, the number of recesses 126 for pixels 50 having each color filter, or the pitch or depth of the recesses 126 for pixels 50 having each color filter, is determined according to the physical characteristics of each complementary color of yellow (Y), cyan (C), green (G), and magenta (M).

[0131] <13. 9th Pixel Configuration Example> In the pixel 50 described above, a color filter layer 105 is provided on the light incident surface side of the semiconductor substrate 101, in which a green filter 131G, a red filter 131R, and a blue filter 131B are arranged in a predetermined arrangement such as a Bayer arrangement. However, in order to improve sensitivity, the film thickness of the green filter 131G was formed to be thinner than that of the red filter 131R and the blue filter 131B.

[0132] If the thickness of the green filter 131G is thinner than that of the red filter 131R and the blue filter 131B, the refractive index of the color filter layer 105 is greater than that of the lens material of the on-chip lens 108. As a result, as shown in Figure 20, it is conceivable that a large amount of light incident on the pixel boundary will be captured by the pixel 50 where the thicker red filter 131R and blue filter 131B are located. The ninth to eleventh configuration examples of the pixel 50 described below describe pixel configurations that suppress the effects of the difference in thickness of the green filter 131G, red filter 131R, and blue filter 131B.

[0133] Figure 21 is a cross-sectional view showing a ninth configuration example of pixel 50.

[0134] In the cross-sectional views of Figures 21, 24, and 25, three pixels 50 having R, G, and B color filters in a Bayer array are shown side by side.

[0135] In the ninth configuration example of pixel 50 shown in Figure 21, a white filter 131W is placed below the green filter 131G of the color filter layer 105. The combined film thickness of the green filter 131G and the white filter 131W is set to be the same as that of the red filter 131R and the blue filter 131B. The white filter 131W is a transparent filter that allows light in the entire wavelength range to pass through.

[0136] In the ninth configuration example in Figure 21, the configuration of the uneven portion 127 is the same for the G pixel 50G, B pixel 50B, and R pixel 50R, but it is also possible to combine it with the other configurations described above. For example, the number of recesses 126 of the uneven portion 127, the planar size (pitch), or the depth may be different for the G pixel 50G and the B pixel 50B and R pixel 50R. Alternatively, the shape of the on-chip lens 108 of the G pixel 50G may be different from that of the B pixel 50B and R pixel 50R. The configuration of the MIM capacitive element 201 described in the sixth configuration example in Figure 14, or the configuration of the reflective film 202 in the seventh configuration example in Figure 18 may also be combined.

[0137] Figure 22 is a plan view showing the arrangement of the color filter layer 105.

[0138] The green filter 131G, red filter 131R, and blue filter 131B are arranged in a Bayer array. The white filter 131W is not shown in Figure 22 because it is superimposed on the green filter 131G.

[0139] <Modified Version of the 9th Configuration Example> Figure 23 is a cross-sectional view showing a modified version of the pixel 50 according to the 9th configuration example.

[0140] In the modified example shown in Figure 23, the arrangement of the green filter 131G and the white filter 131W is the opposite of the configuration shown in Figure 21. That is, in the ninth configuration example shown in Figure 21, the white filter 131W was placed below the green filter 131G, but in the modified example shown in Figure 23, the green filter 131G is placed below, and the white filter 131W is placed above the green filter 131G. The common point is that the combined film thickness of the green filter 131G and the white filter 131W is the same as that of the red filter 131R and the blue filter 131B.

[0141] According to the ninth configuration example, including the modified example described above, by placing the white filter 131W above or below the green filter 131G, the combined film thickness of the green filter 131G and the white filter 131W is configured to be the same as that of the red filter 131R and the blue filter 131B. This prevents light incident on the pixel boundary from being captured in large quantities by the pixels 50 where the red filter 131R and the blue filter 131B are placed, as explained with reference to Figure 20, and allows light to be incident on each pixel 50 evenly. Therefore, it is possible to suppress the difference in sensitivity in the infrared region, which is commonly received by each pixel 50 with different colors in the color filter layer 105.

[0142] <14. Example of the 10th Pixel Configuration> Figure 24 is a cross-sectional view showing an example of the 10th pixel configuration of 50.

[0143] In the tenth configuration example of pixel 50 shown in Figure 24, the white filter 131W is placed not only below the green filter 131G but also below the blue filter 131B. The combined film thickness of the blue filter 131B and the white filter 131W is set to be the same as that of the red filter 131R.

[0144] In other words, the configuration described in Figure 20 assumed that the film thickness of the green filter 131G was thinner than that of the red filter 131R and the blue filter 131B, while the red filter 131R and the blue filter 131B had the same film thickness.

[0145] However, if the film thicknesses of the green filter 131G, red filter 131R, and blue filter 131B are all different, the white filter 131W can be placed above or below the two thinner layers, so that the film thickness including the white filter 131W is the same as that of the thickest red filter 131R. The example in Figure 24 shows the white filter 131W placed below the green filter 131G and blue filter 131B, but as with the modification in Figure 23, the white filter 131W may also be placed above the green filter 131G and blue filter 131B.

[0146] According to the tenth configuration example, by placing the white filter 131W above or below the green filter 131G and the blue filter 131B, the film thickness of all pixels in the color filter layer 105 can be made uniform, and the sensitivity difference in the infrared region, which is commonly received by each pixel 50 with different colors in the color filter layer 105, can be suppressed.

[0147] <15. Eleventh Pixel Configuration Example> Figure 25 is a cross-sectional view showing the eleventh configuration example of pixel 50.

[0148] Comparing the 11th configuration example of the pixel 50 shown in Figure 25 with the 9th configuration example, the inter-pixel separation section 121 of the 9th configuration example has been changed to an inter-pixel separation section 121' in which a P-type semiconductor region 111 is left in a part of the substrate depth direction. Thus, an inter-pixel separation section 121' in which a P-type semiconductor region 111 is left in a part of the substrate depth direction may be combined with a configuration in which the film thickness of the color filter is made uniform by stacking a white filter 131W.

[0149] The example in Figure 25 is an example in which the pixel separation unit 121 of the ninth configuration example shown in Figure 21 is replaced with the pixel separation unit 121'. However, it is also possible to modify the ninth configuration example in Figure 23 and to replace the pixel separation unit 121 of the tenth configuration example in Figure 24 with the pixel separation unit 121'.

[0150] If the photodiode PD is not completely separated on a pixel-by-pixel basis by the inter-pixel separation unit 121', the sensitivity difference in the infrared region will be smaller than when the photodiode PD is completely separated. By stacking the white filter 131W while suppressing the sensitivity difference between pixels of different colors by the inter-pixel separation unit 121', the film thickness of the green filter 131G, red filter 131R, and blue filter 131B is made uniform, further suppressing the sensitivity difference between pixels of different colors. Therefore, even in the 11th configuration example, the sensitivity difference in the infrared region, which is commonly received by each pixel 50 with different colored color filter layers 105, can be suppressed.

[0151] <16. Summary of Configuration Examples 9 to 11> The pixels 50 in Configuration Examples 9 to 11 each have a photodiode PD, which is a photoelectric conversion unit formed on a semiconductor substrate 101, and a color filter layer 105 on the light incident surface side of the semiconductor substrate 101, in which predetermined color filters are arranged in a predetermined arrangement such as a Bayer array.

[0152] The color filter layer 105 of the pixel 50 allows light in a first wavelength region, which differs for each color of the color filter layer 105, and light in a second wavelength region common to all pixels to pass through and be incident on the photodiode PD. The light in the first wavelength region is visible light of R, G, or B, and the light in the second wavelength region is infrared light. The color filter layer 105 has a green filter 131G (first color filter) and a red filter 131R (second color filter) with different film thicknesses, and a white filter 131W is located above or below the green filter 131G, which has a thinner film thickness than the red filter 131R. The combined film thickness of the green filter 131G and the white filter 131W is configured to be the same as that of the red filter 131R. If the film thickness of the blue filter 131B (third color filter) is different from that of both the red filter 131R and the green filter 131G, and is between the film thicknesses of the red filter 131R and the green filter 131G, then a white filter 131W is placed above or below the blue filter 131B. The combined film thickness of the blue filter 131B and the white filter 131W is configured to be the same as that of the red filter 131R, which has the maximum film thickness.

[0153] This allows the film thickness of all the color filters in the color filter layer 105 to be uniform, preventing light incident at the pixel boundary from being absorbed more by pixels 50 where the thicker red filter 131R or blue filter 131B is located, and allowing it to be incident evenly on each pixel 50. Therefore, it is possible to suppress the difference in sensitivity in the infrared region, which is commonly received by each pixel 50 with different colors in the color filter layer 105. Since the film thickness of all the color filters is uniform, there is no need to intentionally increase the film thickness of any of the green filter 131G, red filter 131R, or blue filter 131B, so good sensitivity in visible light can be maintained.

[0154] In the ninth to eleventh configuration examples described above, the green filter 131G has the thinnest film thickness in the color filter layer 105, and when the film thicknesses of the green filter 131G, red filter 131R, and blue filter 131B are all different, an example was described in which the blue filter 131B has the second thinnest film thickness after the green filter 131G, and the red filter 131R has the thickest film thickness. If the film thicknesses of the color filters differ from this example, the white filter 131W is placed above or below the first color filter with the thinnest film thickness, and configured to have the same film thickness as the second color filter with the thickest film thickness.

[0155] Furthermore, in the ninth to eleventh configuration examples described above, an example was explained in which a red filter 131R, a green filter 131G, and a blue filter 131B were arranged as the color filters of the color filter layer 105.

[0156] The color filter arrangement of the color filter layer 105 is not limited to R, G, and B; other color arrangements are also possible. For example, a 2x2 arrangement of 4 pixel color filters may be repeatedly placed in the row and column directions as complementary colors of yellow (Y), cyan (C), green (G), and magenta (M). In this case as well, a white filter is placed above or below the thinner color filters, depending on the film thickness of each complementary color filter (yellow (Y), cyan (C), green (G), and magenta (M)), so that the film thickness of the color filter layer 105 for each pixel 50 is the same.

[0157] <17. Combinations of the First to Eleventh Configuration Examples> The pixel 50 can be configured by appropriately combining the First to Eleventh Configuration Examples described above. For example, a configuration can be adopted in which a white filter 131W is placed above or below the green filter 131G in the first configuration example of Figure 4, so that the combined film thickness of the green filter 131G and the white filter 131W is the same as that of the blue filter 131B and the red filter 131R. Alternatively, for example, the tenth configuration example shown in Figure 24 may be combined with the MIM capacitive element 201 explained in Figures 14, 15, and 17, or the reflective film 202 in Figure 18.

[0158] <18. Examples of Electronic Device Configurations> The light detection device 13 described above can be applied to various electronic devices, such as imaging systems like digital still cameras and digital video cameras, mobile phones equipped with imaging functions, or other devices equipped with imaging functions.

[0159] Figure 26 is a block diagram showing an example of the configuration of an electronic device.

[0160] As shown in Figure 26, the electronic device 301 comprises an optical system 302, a photodetector 303, a DSP (Digital Signal Processor) 304, a display device 305, an operating system 306, a memory 307, a recording device 308, and a power supply system 309. The DSP 304, display device 305, operating system 306, memory 307, recording device 308, and power supply system 309 are interconnected via a bus 310. The electronic device 301 is, for example, an imaging device capable of capturing still images and moving images.

[0161] The optical system 302 is composed of one or more lenses and guides the image light (incident light) from the subject to the light detection device 303, where it forms an image on the light-receiving surface (sensor part) of the light detection device 303.

[0162] The photodetector 303 is configured in the same way as the photodetector 13 described above. In the photodetector 303, electrons are accumulated as signal charges for a certain period of time in accordance with the image formed on the light-receiving surface via the optical system 302. Then, a signal corresponding to the electrons accumulated in the photodetector 303 is supplied to the DSP 304.

[0163] The DSP 304 performs various signal processing on the signal from the light detection device 303 to generate an image, and temporarily stores the image data in the memory 307. The image data stored in the memory 307 is recorded in the recording device 308 or supplied to the display device 305 to display the image. The operation system 306 receives various operations from the user and supplies operation signals to each block of the electronic equipment 301, and the power supply system 309 supplies the power necessary to drive each block of the electronic equipment 301.

[0164] In the electronic device 301 configured in this way, by applying the above-described light detection device 13 as the light detection device 303, a pixel structure that suppresses sensitivity differences between pixels of different colors is realized. Therefore, high-quality captured images can be generated.

[0165] <19. Example of Image Sensor Use> Figure 27 shows an example of use when the above-mentioned light detection device 13 is an image sensor.

[0166] When the above-described light detection device 13 is used as an image sensor, it can be used in various cases to sense light such as visible light, infrared light, ultraviolet light, and X-rays, for example, as shown below.

[0167] - Devices that capture images for viewing purposes, such as digital cameras and portable devices with camera functions. - Devices used for traffic purposes, such as in-vehicle sensors that capture images of the front, rear, surroundings, and interior of a vehicle for safe driving such as automatic stopping and recognition of the driver's condition, surveillance cameras that monitor moving vehicles and roads, and distance measuring sensors that measure distances between vehicles. - Devices used in home appliances such as TVs, refrigerators, and air conditioners that capture user gestures and allow device operation according to those gestures. - Devices used for medical and healthcare purposes, such as endoscopes and devices that perform angiography using infrared light reception. - Devices used for security purposes, such as surveillance cameras for crime prevention and cameras for person recognition. - Devices used for beauty purposes, such as skin measuring devices that capture images of skin and microscopes that capture images of the scalp. - Devices used for sports purposes, such as action cameras and wearable cameras for sports use. - Devices used for agriculture, such as cameras that monitor the condition of fields and crops.

[0168] The embodiments of the technology described herein are not limited to those described above, and various modifications are possible without departing from the spirit of the technology described herein.

[0169] In the example described above, a photodetector was described in which the first conductivity type was P-type and the second conductivity type was N-type, and electrons were used as the signal charge. However, this disclosure can also be applied to a photodetector that uses holes as the signal charge. That is, the first conductivity type can be N-type and the second conductivity type can be P-type, and the aforementioned semiconductor regions can be composed of semiconductor regions of the opposite conductivity types.

[0170] Furthermore, this disclosure is not limited to applications to photodetectors that detect the distribution of incident light intensity of visible light and capture it as an image, but is also applicable to photodetectors that capture the distribution of incident amounts of infrared rays, X-rays, or particles as an image, and, in a broader sense, to all photodetectors (physical quantity distribution detection devices) such as fingerprint detection sensors that detect the distribution of other physical quantities such as pressure and capacitance and capture it as an image.

[0171] In this specification, a system means a collection of multiple components (devices, modules (parts), etc.), regardless of whether all components are located in the same enclosure. Therefore, multiple devices housed in separate enclosures and connected via a network, and a single device containing multiple modules in one enclosure, are both considered systems.

[0172] Furthermore, the effects described herein are merely illustrative and not limiting, and other effects may also occur.

[0173] The technology disclosed herein may employ the following configurations: (1) A light detection device comprising a pixel array in which a plurality of pixels are arranged in two dimensions, wherein each pixel has a photoelectric conversion unit formed on a semiconductor substrate and a color filter layer that allows light in a predetermined wavelength range to pass through and is incident on the photoelectric conversion unit, wherein at least one of the number, pitch, or depth of recesses formed on the light incident surface of the semiconductor substrate is different for the pixels of the first color filter of the color filter layer and the pixels of the second color filter of the color filter layer. (2) The light detection device according to (1) wherein the color filter layer allows light in a first wavelength range different for each color of the color filter layer and light in a second wavelength range common to all pixels to pass through. (3) The light detection device according to (1) or (2) wherein the number of recesses is different for the pixels of the first color filter of the color filter layer and the pixels of the second color filter of the color filter layer. (4) The light detection device according to any one of (1) to (3), wherein the pitch and depth of the recesses differ between the pixels of the first color filter of the color filter layer and the pixels of the second color filter. (5) The light detection device according to any one of (1) to (4), wherein the presence or absence of the recesses differs between the pixels of the first color filter of the color filter layer and the pixels of the second color filter. (6) The light detection device according to any one of (1) to (5), wherein the pixels further have an inter-pixel separation section that separates the photoelectric conversion section into pixel units. (7) The light detection device according to (6), wherein the inter-pixel separation section penetrates the semiconductor substrate from the light incident surface to the surface opposite to the light incident surface, separating the photoelectric conversion section into pixel units. (8) The photodetector according to (6), wherein the inter-pixel isolation portion has a trench of a predetermined depth from the light incident surface of the semiconductor substrate, and on the side opposite to the light incident surface, has a semiconductor region of a second conductivity type opposite to a semiconductor region of a first conductivity type that constitutes the charge storage region of the photoelectric conversion portion of the pixel. (9) The photodetector according to any one of (6) to (8), wherein the inter-pixel isolation portion is configured by embedding at least one of an insulating film, polysilicon, an air gap, and a metallic material in the trench formed in the semiconductor substrate.(10) The light detection device according to any one of (1) to (9), wherein the pixel has a wiring layer on the side opposite to the light incident surface of the semiconductor substrate, and the wiring layer has a reflective structure that reflects light that penetrates the semiconductor substrate and is incident on the wiring layer. (11) The light detection device according to (10), wherein the arrangement, planar area, or presence or absence of the reflective structure differs between the pixel of the first color filter of the color filter layer and the pixel of the second color filter. (12) The light detection device according to any one of (10) to (11), wherein the reflective structure is composed of a capacitive element or a reflective film. (13) The light detection device according to any one of (10) to (12), wherein the pixel is composed of a first semiconductor substrate having the semiconductor substrate and a second semiconductor substrate stacked together, and the reflective structure is arranged between the first semiconductor substrate and the second semiconductor substrate. (14) The light detection device according to any one of (1) to (13), wherein the pixel further comprises an on-chip lens, and the curvature of the on-chip lens differs between the pixel of the first color filter and the pixel of the second color filter of the color filter layer. (15) The light detection device according to any one of (1) to (14), wherein one on-chip lens is arranged for a plurality of pixels, and the color filter layer has a predetermined arrangement of color filters with the plurality of pixels on which the one on-chip lens is arranged as the same color arrangement unit. (16) The light detection device according to any one of (1) to (15), wherein the color filter layer has different film thicknesses for the first color filter and the second color filter. (17) The light detection device according to any one of (1) to (16), wherein the color filter layer has a white filter above or below the first color filter, which has a thinner film thickness than the second color filter. (18) A photodetector comprising a pixel array in which a plurality of pixels are arranged in two dimensions, wherein each pixel has a photoelectric conversion unit formed on a semiconductor substrate and a color filter layer that allows light in a predetermined wavelength range to pass through and be incident on the photoelectric conversion unit, and the color filter layer has a first color filter and a second color filter having different film thicknesses, and a white filter having a film thickness thinner than the second color filter above or below the first color filter.(19) The light detection device according to (18), wherein the color filter layer allows light in a first wavelength region different for each color of the color filter layer and light in a second wavelength region common to all pixels to pass through. (20) The light detection device according to (19), wherein the light in the first wavelength region is visible light and the light in the second wavelength region is infrared light. (21) The light detection device according to any one of (19) to (20), wherein the photoelectric conversion unit converts the light reflected by the subject when light in the second wavelength region is irradiated from the light source device into photoelectric energy. (22) The light detection device according to any one of (18) to (21), wherein the combined film thickness of the first color filter and the white filter is the same as that of the second color filter. (23) The photodetector according to any one of (18) to (22), wherein the color filter layer further comprises a third color filter having a film thickness different from that of either the first color filter or the second color filter, and the film thickness of the third color filter is the film thickness between that of the first color filter and the second color filter, and the white filter is located above or below the third color filter. (24) The photodetector according to (23), wherein the combined film thickness of the third color filter and the white filter is the same as that of the second color filter. (25) The photodetector according to any one of (18) to (24), wherein the pixels further comprises an inter-pixel separation unit that separates the photoelectric conversion unit into pixel units. (26) The photodetector according to (25), wherein the inter-pixel separation unit penetrates the semiconductor substrate from the light incident surface to the surface opposite to the light incident surface, separating the photoelectric conversion unit into pixel units. (27) The photodetector according to (25), wherein the inter-pixel separation portion has a trench of a predetermined depth from the light incident surface of the semiconductor substrate, and on the side opposite to the light incident surface, there is a semiconductor region of a second conductivity type opposite to a semiconductor region of a first conductivity type that constitutes the charge storage region of the photoelectric conversion portion of the pixel.

[0174] 1 Imaging system, 11 Control device, 12 Light source device, 13 Light detection device, 20 Subject, 41 Pixel array, 50 Pixel, 101 Semiconductor substrate, 102 Wiring layer, 103 Fixed charge film, 104 Insulating film, 105 Color filter layer, 106 Inter-pixel light shielding film, 107 Planarization film, 108 On-chip lens, 109 Anti-reflective film, 111 P-type semiconductor region, 112 N-type semiconductor region, 121, 121' Inter-pixel separation region, 122 Fixed charge film, 123 Insulating film, 124 Air gap, 126 Recess, 127 Uneven region, 131B Blue filter, 131G Green filter, 131R Red filter, 131W White filter, 151 Metal wiring, 152 SiO2 film, 171 infrared region, 201 MIM capacitive element, 202 reflective film, 211 planar electrode section, 212 vertical electrode section, 221 first substrate, 222 second substrate, 223 third substrate, 251 semiconductor substrate, 252 wiring layer, 253 insulating layer, 271 semiconductor substrate, 272 wiring layer, 281 metal wiring, 282 interlayer insulating film, 283 junction electrode, 291 metal wiring, 292 interlayer insulating film, 293 junction electrode

Claims

1. A light detection device comprising a pixel array in which a plurality of pixels are arranged in two dimensions, wherein each pixel has a photoelectric conversion unit formed on a semiconductor substrate and a color filter layer that allows light in a predetermined wavelength range to pass through and be incident on the photoelectric conversion unit, and at least one of the number, pitch, or depth of recesses formed on the light incident surface of the semiconductor substrate is different for the pixels of the first color filter and the pixels of the second color filter of the color filter layer.

2. The light detection device according to claim 1, wherein the color filter layer allows light in a first wavelength region that differs for each color of the color filter layer and light in a second wavelength region that is common to all pixels to pass through.

3. The light detection device according to claim 1, wherein the number of recesses differs between the pixels of the first color filter and the pixels of the second color filter in the color filter layer.

4. The light detection device according to claim 1, wherein the pitch and depth of the recesses differ between the pixels of the first color filter and the pixels of the second color filter of the color filter layer.

5. The light detection device according to claim 1, wherein the presence or absence of the recess differs between the pixels of the first color filter and the pixels of the second color filter of the color filter layer.

6. The photodetector according to claim 1, wherein the pixel further comprises an inter-pixel separation unit that separates the photoelectric conversion unit into pixel units.

7. The photodetector according to claim 6, wherein the inter-pixel separation unit penetrates the semiconductor substrate from the light incident surface to the surface opposite to the light incident surface, separating the photoelectric conversion unit on a pixel-by-pixel basis.

8. The photodetector according to claim 6, wherein the inter-pixel separation portion has a trench of a predetermined depth from the light incident surface of the semiconductor substrate, and on the side opposite to the light incident surface, has a semiconductor region of a second conductivity type opposite to the semiconductor region of a first conductivity type that constitutes the charge storage region of the photoelectric conversion portion of the pixel.

9. The photodetector according to claim 6, wherein the inter-pixel separation portion is configured by embedding at least one of an insulating film, polysilicon, an air gap, and a metallic material in a trench formed in the semiconductor substrate.

10. The light detection device according to claim 1, wherein the pixel has a wiring layer on the side of the semiconductor substrate opposite to the light incident surface, and the wiring layer has a reflective structure that reflects light that penetrates the semiconductor substrate and is incident on the wiring layer.

11. The light detection device according to claim 10, wherein the arrangement, surface area, or presence or absence of the reflective structure differs between the pixels of the first color filter and the pixels of the second color filter of the color filter layer.

12. The photodetector according to claim 10, wherein the reflective structure is composed of a capacitive element or a reflective film.

13. The photodetector according to claim 10, wherein the pixel is constructed by stacking a first substrate having the semiconductor substrate as a first semiconductor substrate and a second substrate having a second semiconductor substrate, and the reflective structure is disposed between the first semiconductor substrate and the second semiconductor substrate.

14. The light detection device according to claim 1, wherein the pixel further comprises an on-chip lens, and the curvature of the on-chip lens differs between the pixel of the first color filter of the color filter layer and the pixel of the second color filter.

15. The light detection device according to claim 1, wherein one on-chip lens is arranged for a plurality of pixels, and the color filter layer has an arrangement of predetermined color filters with the plurality of pixels on which the one on-chip lens is arranged as the same color arrangement unit.

16. The photodetector according to claim 1, wherein the color filter layer has different film thicknesses for the first color filter and the second color filter.

17. The photodetector according to claim 16, wherein the color filter layer has a white filter above or below the first color filter, having a thinner film thickness than the second color filter.

18. A photodetector comprising a pixel array in which a plurality of pixels are arranged in two dimensions, wherein each pixel has a photoelectric conversion unit formed on a semiconductor substrate and a color filter layer that allows light in a predetermined wavelength range to pass through and be incident on the photoelectric conversion unit, and the color filter layer has a first color filter and a second color filter with different film thicknesses, and a white filter having a film thickness thinner than the second color filter above or below the first color filter.

19. The light detection device according to claim 18, wherein the color filter layer allows light in a first wavelength region that differs for each color of the color filter layer and light in a second wavelength region that is common to all pixels to pass through.

20. The photodetector according to claim 19, wherein the light in the first wavelength region is visible light, and the light in the second wavelength region is infrared light.

21. The photoelectric conversion unit photoelectrically converts light reflected from an object when light in the second wavelength region is irradiated from a light source device.

22. The photodetector according to claim 18, wherein the combined film thickness of the first color filter and the white filter is the same as that of the second color filter.

23. The photodetector according to claim 18, wherein the color filter layer further comprises a third color filter having a film thickness different from that of either the first color filter or the second color filter, and the film thickness of the third color filter is between the film thickness of the first color filter and the second color filter, and the white filter is located above or below the third color filter.

24. The photodetector according to claim 23, wherein the combined film thickness of the third color filter and the white filter is the same as that of the second color filter.

25. The photodetector according to claim 18, wherein the pixel further comprises an inter-pixel separation unit that separates the photoelectric conversion unit into pixel units.

26. The photodetector according to claim 25, wherein the inter-pixel separation unit penetrates the semiconductor substrate from the light incident surface to the surface opposite to the light incident surface, separating the photoelectric conversion unit on a pixel-by-pixel basis.

27. The photodetector according to claim 25, wherein the inter-pixel separation portion has a trench of a predetermined depth from the light incident surface of the semiconductor substrate, and on the side opposite to the light incident surface, has a semiconductor region of a second conductivity type opposite to the semiconductor region of a first conductivity type that constitutes the charge storage region of the photoelectric conversion portion of the pixel.

Images