JP2024059430A - Light detection device - Google Patents

Abstract

To provide a light detection device capable of improving color balance together with sensitivity improvement.SOLUTION: According to one embodiment of the present disclosure, a first light detection device includes: a semiconductor substrate having a first surface and a second surface which face each other with a plurality of first pixels and second pixels for selectively and photoelectrically converting wavelengths different from each other arranged in a matrix; a wavelength separation structure where media having refraction indexes different from each other are planarly and discretely provided for the respective first pixels and second pixels on the first surface side, and which separates, in the first pixels, incident light into first wavelength components and the other wavelength components to selectively guide the first wavelength components to the first pixels, and separate, in the second pixels, the incident light into second wavelength components and the other wavelength components to selectively guide the second wavelength components to the second pixels; and an aperture adjustment structure provided on the first surface side to make an effective pixel aperture size of pixels of ones having relatively lower photosensitivity between the first pixels and the second pixels larger than those of the other pixels.SELECTED DRAWING: Figure 1

Description

This disclosure relates to a photodetector having a wavelength separation structure.

For example, Patent Document 1 discloses an image sensor that uses a nanopost structure to scatter or diffract light and spatially separate wavelengths to improve light utilization efficiency.

JP 2021-069119 A

However, there is a demand for improved color balance in light detection devices.

It is desirable to provide a photodetection device that can improve color balance while increasing sensitivity.

A first photodetector according to an embodiment of the present disclosure includes a semiconductor substrate having opposing first and second surfaces, on which a plurality of first and second pixels that selectively perform photoelectric conversion of wavelengths different from each other are arranged in a matrix, a wavelength separation structure in which media having different refractive indices are provided planarly and discretely on the first surface side of the first pixel and the second pixel, the first pixel separates the incident light into a first wavelength component and other wavelength components and selectively guides the first wavelength component to the first pixel, and the second pixel separates the incident light into a second wavelength component and other wavelength components and selectively guides the second wavelength component to the second pixel, and an aperture adjustment structure provided on the first surface side that makes the effective pixel aperture size of one of the first and second pixels, which has a relatively low photosensitivity, larger than that of the other pixel.

A second photodetector according to an embodiment of the present disclosure includes a semiconductor substrate having opposing first and second surfaces, in which a plurality of first and second pixels that selectively perform photoelectric conversion of wavelengths different from each other are arranged in a matrix, a wavelength separation structure in which media having different refractive indices are provided planarly and discretely on the first surface side of the first pixels and second pixels, in which the first pixels separate incident light into a first wavelength component and other wavelength components and selectively guide the first wavelength component to the first pixel, and the second pixels separate incident light into a second wavelength component and other wavelength components and selectively guide the second wavelength component to the second pixel, and a light-collecting element provided on the first surface side of the first and second pixels that have a relatively low photosensitivity.

A third photodetector according to an embodiment of the present disclosure includes a semiconductor substrate having opposing first and second surfaces, on which a plurality of first pixels and second pixels that selectively perform photoelectric conversion on wavelengths different from each other are arranged in a matrix, and a medium having a refractive index different from each other is provided planarly and discretely on the first surface side of the first pixel and the second pixel, respectively, and the first pixel separates incident light into a first wavelength component and other wavelength components and selectively guides the first wavelength component to the first pixel, and the second pixel separates incident light into a second wavelength component and other wavelength components and selectively guides the first wavelength component to the first pixel. The device includes a wavelength separation structure that separates the first wavelength component into a long wavelength component and a second wavelength component and selectively guides the second wavelength component to the second pixel, a frame body that is provided between the first surface and the wavelength separation structure at the boundary between the adjacent first pixel and second pixel and has an opening in each of the first pixel and the second pixel, and a color filter layer that is filled in the opening and is made of a color filter that selectively transmits the wavelength that is photoelectrically converted in each of the first pixel and the second pixel, and the size of the opening is larger for the pixel with relatively low photosensitivity than for the other pixels.

In a first photodetector according to an embodiment of the present disclosure, a wavelength separation structure and an aperture adjustment structure are provided on the first surface side, which is the light incident surface of a semiconductor substrate on which a plurality of first pixels and second pixels that selectively convert different wavelengths into electric signals are arranged in a matrix. In the wavelength separation structure, a medium having a different refractive index is provided planarly and discretely on each of the first pixel and the second pixel, and the first pixel separates the incident light into a first wavelength component and other wavelength components and selectively guides the first wavelength component to the first pixel, and the second pixel separates the incident light into a second wavelength component and other wavelength components and selectively guides the second wavelength component to the second pixel. The aperture adjustment structure is provided on the first surface side, and makes the effective pixel aperture size of one of the first and second pixels, which has a relatively low photosensitivity, larger than that of the other pixel. In a second photodetector according to an embodiment of the present disclosure, a light collecting element is provided on the pixel having a relatively low photosensitivity of the first and second pixels, as the aperture adjustment structure. In a third photodetector according to an embodiment of the present disclosure, a frame body is provided between the first surface and the wavelength separation structure at the boundary between the adjacent first and second pixels, and has an opening in each of the first and second pixels. The frame body and the color filter layer are filled in the openings and selectively transmit the wavelengths photoelectrically converted in the first and second pixels. The color filter layer is an aperture adjustment structure, and the aperture size of the pixel with a relatively low photosensitivity is made larger than the aperture size of the other pixels. This improves the quantum efficiency of the pixel with a relatively low photosensitivity.

1 is a schematic cross-sectional view illustrating an example of a configuration of a light detection device according to a first embodiment of the present disclosure. 2 is a block diagram showing an overall configuration of the photodetector shown in FIG. 1 . 2 is an equivalent circuit diagram of the unit pixel shown in FIG. 1 . 2 is a schematic diagram illustrating an example of a planar layout of the photodetector illustrated in FIG. 1 . 5 is a perspective view showing a schematic diagram of a light detection device having the planar layout shown in FIG. 4. FIG. 2 is a schematic cross-sectional view of a photodetector according to a first embodiment of the present invention; FIG. 11 is a schematic cross-sectional view of a photodetector according to a second embodiment of the present invention; 7 is a characteristic diagram showing the quantum efficiency of R, G, and B in the photodetector shown in FIG. 6. 8 is a characteristic diagram showing the quantum efficiency of R, G, and B in the photodetector shown in FIG. 7 . 2 is a characteristic diagram showing the quantum efficiency of R, G, and B in the photodetector shown in FIG. 1 . 1 is a schematic cross-sectional view illustrating an example of a configuration of a light detection device according to a first modified example of the present disclosure. 11 is a schematic cross-sectional view illustrating an example of a configuration of a light detection device according to a second modified example of the present disclosure. FIG. 11 is a schematic cross-sectional view illustrating an example of a configuration of a light detection device according to a third modified example of the present disclosure. FIG. 13 is a schematic cross-sectional view illustrating another example of the configuration of a light detection device according to Modification 3 of the present disclosure. FIG. 13 is a schematic cross-sectional view illustrating another example of the configuration of a light detection device according to Modification 3 of the present disclosure. FIG. 13 is a schematic cross-sectional view illustrating an example of a configuration of a light detection device according to a fourth modified example of the present disclosure. FIG. FIG. 11 is a schematic cross-sectional view illustrating an example of a configuration of a light detection device according to a second embodiment of the present disclosure. 18 is a schematic diagram illustrating an example of a planar layout of the photodetector shown in FIG. 17. 2 is a block diagram illustrating an example of the configuration of an electronic device having the photodetector shown in FIG. 1 . 2 is a schematic diagram illustrating an example of an overall configuration of a light detection system using the light detection device illustrated in FIG. 1 etc. 20B is a diagram illustrating an example of a circuit configuration of the light detection system illustrated in FIG. 20A. 1 is a block diagram showing an example of a schematic configuration of a vehicle control system; 4 is an explanatory diagram showing an example of the installation positions of an outside-vehicle information detection unit and an imaging unit; FIG. 1 is a diagram illustrating an example of a schematic configuration of an endoscopic surgery system. 2 is a block diagram showing an example of the functional configuration of a camera head and a CCU. FIG.

Hereinafter, an embodiment of the present disclosure will be described in detail with reference to the drawings. The following description is a specific example of the present disclosure, and the present disclosure is not limited to the following aspect. Furthermore, the present disclosure is not limited to the arrangement, dimensions, dimensional ratios, etc. of each component shown in each drawing. The order of description is as follows.
1. First embodiment (example in which an on-chip lens is used as an aperture adjustment structure)
2. Modifications 2-1. Modification 1 (Example of using an inner lens as the aperture adjustment structure)
2-2. Modification 2 (another example using an inner lens as the aperture adjustment structure)
2-3. Modification 3 (Example of using an on-chip lens and an inner lens as an aperture adjustment structure)
2-4. Modification 4 (Layout example of on-chip lenses in a layout in which pixels of the same color are adjacent to each other)
3. Second embodiment (example in which a color filter layer is used as an aperture adjustment structure)
4. Application examples 5. Application examples

1. First embodiment
Fig. 1 is a schematic diagram showing an example of a cross-sectional configuration of a photodetector (photodetector 1) according to a first embodiment of the present disclosure. Fig. 2 is a diagram showing an example of the overall configuration of the photodetector 1 shown in Fig. 1. The photodetector 1 is, for example, a CMOS (Complementary Metal Oxide Semiconductor) image sensor used in electronic devices such as digital still cameras and video cameras, and has a pixel section (pixel section 100A) in which a plurality of pixels are two-dimensionally arranged in a matrix as an imaging area. The photodetector 1 is, for example, a so-called back-illuminated photodetector in this CMOS image sensor or the like.

[Schematic configuration of the photodetector]
The photodetector 1 captures incident light (image light) from a subject via an optical lens system (e.g., a lens group 1001, see FIG. 19), converts the amount of incident light imaged on an imaging surface into an electrical signal on a pixel-by-pixel basis, and outputs the electrical signal as a pixel signal. The photodetector 1 has a pixel section 100A as an imaging area on a semiconductor substrate 11, and has, for example, a vertical drive circuit 111, a column signal processing circuit 112, a horizontal drive circuit 113, an output circuit 114, a control circuit 115, and an input/output terminal 116 in the peripheral region of the pixel section 100A.

In the pixel section 100A, for example, a plurality of unit pixels P are arranged two-dimensionally in a matrix. The plurality of unit pixels P photoelectrically converts the subject image formed by the imaging lens in a photodiode PD to generate a signal for generating an image.

In the unit pixel P, for example, a pixel drive line Lread (specifically, a row selection line and a reset control line) is wired for each pixel row, and a vertical signal line Lsig is wired for each pixel column. The pixel drive line Lread transmits a drive signal for reading out a signal from the pixel. One end of the pixel drive line Lread is connected to an output terminal of the vertical drive circuit 111 corresponding to each row.

The vertical drive circuit 111 is a pixel drive unit that is composed of a shift register, an address decoder, etc., and drives each unit pixel P of the pixel section 100A, for example, row by row. The signals output from each unit pixel P of the pixel row selected and scanned by the vertical drive circuit 111 are supplied to the column signal processing circuit 112 through each vertical signal line Lsig. The column signal processing circuit 112 is composed of an amplifier, a horizontal selection switch, etc., provided for each vertical signal line Lsig.

The horizontal drive circuit 113 is composed of a shift register, an address decoder, etc., and drives each horizontal selection switch of the column signal processing circuit 112 in sequence while scanning them. Through selective scanning by this horizontal drive circuit 113, the signals of each pixel transmitted through each vertical signal line Lsig are output in sequence to the horizontal signal line 121, and transmitted to the outside of the semiconductor substrate 11 through the horizontal signal line 121.

The output circuit 114 processes and outputs the signals sequentially supplied from each of the column signal processing circuits 112 via the horizontal signal line 121. The output circuit 114 may perform only buffering, or may perform black level adjustment, column variation correction, various digital signal processing, etc., for example.

The circuit portion consisting of the vertical drive circuit 111, column signal processing circuit 112, horizontal drive circuit 113, horizontal signal line 121, and output circuit 114 may be formed directly on the semiconductor substrate 11, or may be disposed on an external control IC. In addition, these circuit portions may be formed on other substrates connected by cables or the like.

The control circuit 115 receives a clock and data instructing the operation mode provided from outside the semiconductor substrate 11, and also outputs data such as internal information of the photodetector 1. The control circuit 115 further has a timing generator that generates various timing signals, and controls the driving of peripheral circuits such as the vertical drive circuit 111, the column signal processing circuit 112, and the horizontal drive circuit 113 based on the various timing signals generated by the timing generator.

The input/output terminal 116 is used to exchange signals with the outside world.

[Circuit configuration of unit pixel]
Fig. 3 illustrates an example of a readout circuit of the unit pixel P of the photodetector 1 illustrated in Fig. 2. As illustrated in Fig. 3, the unit pixel P includes, for example, one photoelectric conversion unit 12, a transfer transistor TR, a floating diffusion FD, a reset transistor RST, an amplification transistor AMP, and a selection transistor SEL.

The photoelectric conversion unit 12 is a photodiode (PD). The anode of the photoelectric conversion unit 12 is connected to the ground voltage line, and the cathode is connected to the source of the transfer transistor TR1.

The transfer transistor TR1 is connected between the photoelectric conversion unit 12 and the floating diffusion FD. A drive signal TRsig is applied to the gate electrode of the transfer transistor TR. When this drive signal TRsig becomes active, the transfer gate of the transfer transistor TR becomes conductive, and the signal charge stored in the photoelectric conversion unit 12 is transferred to the floating diffusion FD via the transfer transistor TR.

The floating diffusion FD is connected between the transfer transistor TR and the amplification transistor AMP. The floating diffusion FD converts the signal charge transferred by the transfer transistor TR into a voltage signal and outputs it to the amplification transistor AMP.

The reset transistor RST is connected between the floating diffusion FD and the power supply unit. A drive signal RSTsig is applied to the gate electrode of the reset transistor RST. When this drive signal RSTsig becomes active, the reset gate of the reset transistor RST becomes conductive, and the potential of the floating diffusion FD is reset to the level of the power supply unit.

The amplifier transistor AMP has its gate electrode connected to the floating diffusion FD and its drain electrode connected to the power supply, and serves as the input of a readout circuit for the voltage signal held by the floating diffusion FD, a so-called source follower circuit. That is, the amplifier transistor AMP has its source electrode connected to the vertical signal line Lsig via the selection transistor SEL, and thus constitutes a constant current source and a source follower circuit connected to one end of the vertical signal line Lsig.

The selection transistor SEL is connected between the source electrode of the amplification transistor AMP and the vertical signal line Lsig. A drive signal SELsig is applied to the gate electrode of the selection transistor SEL. When this drive signal SELsig becomes active, the selection transistor SEL becomes conductive and the unit pixel P becomes selected. As a result, the read signal (pixel signal) output from the amplification transistor AMP is output to the vertical signal line Lsig via the selection transistor SEL.

[Configuration of unit pixel]
Fig. 4 is a schematic diagram showing an example of a planar layout of the photodetector 1 shown in Fig. 1, and Fig. 1 shows a cross-sectional configuration of the photodetector 1 corresponding to the line II' shown in Fig. 4. Fig. 5 is a schematic perspective view of the photodetector 1 having the planar layout shown in Fig. 4. As described above, the photodetector 1 is, for example, a back-illuminated photodetector, and each of the unit pixels P arranged two-dimensionally in a matrix in the pixel section 100A has a configuration in which, for example, a light receiving section 10, a light guide section 20 provided on the light incident side S1 of the light receiving section 10, and a multilayer wiring layer 30 provided on the side opposite to the light incident side S1 of the light receiving section 10 are stacked.

The light receiving unit 10 has a semiconductor substrate 11 having a first surface 11S1 and a second surface 11S2 facing each other, and a plurality of photoelectric conversion units 12 embedded in the semiconductor substrate 11. The semiconductor substrate 11 is, for example, made of a silicon substrate. The photoelectric conversion units 12 are, for example, PIN (Positive Intrinsic Negative) type photodiodes (PD), and have a pn junction in a predetermined region of the semiconductor substrate 11. As described above, one photoelectric conversion unit 12 is embedded in each unit pixel P.

The light receiving section 10 further has an element isolation section 13.

The element isolation section 13 is provided between adjacent unit pixels P. In other words, the element isolation section 13 is provided around the unit pixel P and is provided in a lattice pattern in the pixel section 100A. The element isolation section 13 is for electrically and optically isolating adjacent unit pixels P, and extends, for example, from the first surface 11S1 side of the semiconductor substrate 11 toward the second surface 11S2 side. The element isolation section 13 can be formed, for example, by diffusing p-type impurities. In addition, the element isolation section 13 may be, for example, an STI (Shallow Trench Isolation) structure or an FFTI (Full Trench Isolation) structure in which an opening is formed in the semiconductor substrate 11 from the first surface 11S1 side, the side and bottom surfaces of the opening are covered with a fixed charge layer 14, and an insulating layer is embedded. In addition, an air gap may be formed in the STI structure and the FFTI structure.

The first surface 11S1 of the semiconductor substrate 11 is further provided with a fixed charge layer 14 that also serves to prevent reflection on the first surface 11S1 of the semiconductor substrate 11. The fixed charge layer 14 may be a film having a positive fixed charge or a film having a negative fixed charge. Examples of the material of the fixed charge layer 14 include a semiconductor material or a conductive material having a band gap wider than the band gap of the semiconductor substrate 11. Specifically, for example, hafnium oxide (HfO _x ), aluminum oxide (AlO _x ), zirconium oxide (ZrO _x ), tantalum oxide (TaO _x ), titanium oxide (TiO _x ), lanthanum oxide (LaO _x ), praseodymium oxide (PrO _x ), cerium oxide (CeO _x ), neodymium oxide (NdO _x ), promethium oxide (PmO _x ), samarium oxide (SmO _x ), europium oxide (EuO _x ), gadolinium oxide (GdO _x ), terbium oxide (TbO _x ), dysprosium oxide (DyO _x ), holmium oxide (HoO _x ), thulium oxide (TmO _x ), ytterbium oxide (YbO _x ), lutetium oxide (LuO _x ), yttrium oxide (YO _x ), hafnium nitride (HfN _x ), aluminum nitride (AlN _x ), hafnium oxynitride (HfO _x N _y ), aluminum oxynitride (AlO _x N _y ), etc. The fixed charge layer 14 may be a single layer film or a laminated film made of different materials.

The light guide section 20 has, for example, a color filter layer 23 and a transparent layer 24 on the light incident side S1 of the light receiving section 10, and guides the light incident from the light incident side S1 to the light receiving section 10. The color filter layer 23 is composed of, for example, a partition wall 21 and a color filter 22. The transparent layer 24 has, within the layer, a wavelength separation layer 26 including a spectroscopic section 25 provided for each unit pixel P, and an on-chip lens 24L is provided on the surface of the light incident side S1.

The partition 21 is provided at the boundary between adjacent unit pixels P and is a frame having an opening 21H for each unit pixel P. In other words, the partition 21 is provided around the unit pixel P in the same manner as the element isolation section 13, and is provided in a lattice pattern in the pixel section 100A. The partition 21 is intended to prevent light obliquely incident from the light incident side S1 from leaking into an adjacent unit pixel P. The partition 21 can be formed, for example, using a material with a lower refractive index than the color filter 22.

The partition 21 may also serve as a light shield for the unit pixel P that determines the optical black level. The partition 21 may also serve as a light shield to suppress the generation of noise in a peripheral circuit provided in the peripheral region of the pixel unit 100A. In this case, the partition 21 may be formed, for example, using a material having light shielding properties. Examples of such materials include tungsten (W), silver (Ag), copper (Cu), titanium (Ti), aluminum (Al), or alloys thereof. Other examples include metal compounds such as TiN. The partition 21 may be formed, for example, as a single layer film or a laminated film. In the case of a laminated film, for example, a layer made of Ti, tantalum (Ta), W, cobalt (Co), or molybdenum (Mo), or an alloy, nitride, oxide, or carbide thereof may be provided as an underlayer.

The color filters 22 selectively transmit light of a predetermined wavelength, and include, for example, a red filter 22R that selectively transmits red light (R), a green filter 22G that selectively transmits green light (G), and a blue filter 22B that selectively transmits blue light (B). Each of the color filters 22R, 22G, and 22B is filled in the opening 21H of the partition 21. Specifically, for each of the color filters 22R, 22G, and 22B, two green filters 22G are arranged diagonally, and one red filter 22R and one blue filter 22B are arranged on the diagonal lines perpendicular to each other, for four unit pixels P arranged in two rows and two columns, as shown in FIG. 4. In the unit pixel P provided with each of the color filters 22R, 22G, and 22B, for example, the corresponding color light is selectively photoelectrically converted in each photoelectric conversion unit 12.

That is, in the pixel section 100A, unit pixels P (red pixels Pr) that selectively receive and photoelectrically convert red light (R), unit pixels P (green pixels Pg) that selectively receive and photoelectrically convert green light (G), and unit pixels P (blue pixels Pb) that selectively receive and photoelectrically convert blue light (B) are arranged in a Bayer pattern. The red pixels Pr, green pixels Pg, and blue pixels Pb generate pixel signals of the red light (R) component, the green light (G) component, and the blue light (B) component, respectively. The photodetection device 1 can obtain RGB pixel signals.

The color filter 22 may have filters that selectively transmit cyan, magenta, and yellow, respectively. In a unit pixel P in which each color filter 22R, 22G, and 22B is provided, for example, the corresponding color light is detected in each photoelectric conversion unit 12. The color filter 22 may be formed, for example, by dispersing a pigment or dye in a resin material. The film thickness of the color filter 22 may be different for each color, taking into account the color reproducibility and sensor sensitivity due to the spectral distribution.

The transparent layer 24 is a transparent layer that transmits light. The transparent layer 24 has a refractive index of, for example, 1.5 or less with respect to light (incident light) incident from the light incident side S1. The transparent layer 24 is formed using, for example, silicon oxide (SiO ₂ ), silicon oxide doped with fluorine (SiOF), fluororesin, porous silica, or a mixture of these materials.

As described above, the wavelength separation layer 26 including the spectroscopic section 25 is provided within the transparent layer 24. The wavelength separation layer 26 corresponds to one specific example of the "wavelength separation structure" of the present disclosure. The wavelength separation structure has a first medium and a second medium with mutually different refractive indices, and in this embodiment, for example, the spectroscopic section 25 provided for each unit pixel P corresponds to the "second medium", and the transparent layer 24 around the spectroscopic section 25 corresponds to the "first medium".

The wavelength separation layer 26 separates the incident light into a predetermined wavelength component and other wavelength components at each unit pixel P by using, for example, one or more spectroscopic sections 25 provided planarly and discretely for each unit pixel P, and selectively guides the predetermined wavelength component to the unit pixel P in which the spectroscopic section 25 is provided, and guides the other wavelength components to other unit pixels P. The wavelength separation layer 26 generates a phase delay in the incident light due to the difference between the refractive index of the spectroscopic section 25 and the refractive index of the surrounding medium (transparent layer 24), and affects the wavefront. The wavelength separation layer 26 can also be said to be a region (spectroscopic region) in which the incident light is spectroscopically separated by the spectroscopic section 25.

The spectroscopic section 25 is a minute structure, for example, one or more of which are provided for each unit pixel P, and has, for example, a columnar structure (pillar structure) with a size equal to or smaller than a predetermined wavelength of the incident light. The size, shape, refractive index, etc. of the spectroscopic section 25 are determined so that light of each wavelength range contained in the incident light branches and travels in the desired direction. Parameters related to the phase difference of the spectroscopic section 25 include the refractive index of the medium and the height and diameter of the spectroscopic section 25. For example, the spectroscopic section 25 provided for each color pixel Pr, Pg, Pb each has a diameter of, for example, 50 nm or more and 500 nm or less. The height of the spectroscopic section 25 may be about one frequency of the wavelength of the incident light, for example, 500 nm or more and 1500 nm or less.

In each of the light splitting sections 25 provided in each of the color pixels Pr, Pg, and Pb, the propagation direction of light changes for each wavelength range due to the occurrence of different phase delay amounts depending on the wavelength of light. For example, of the light incident on the red pixel Pr, red light (R) is guided directly to the photoelectric conversion section 12 of the red pixel Pr, and light of other wavelengths propagates toward the photoelectric conversion section 12 of the green pixel Pg and blue pixel Pb adjacent to the red pixel Pr. For example, of the light incident on the green pixel Pg, green light (G) is guided directly to the photoelectric conversion section 12 of the green pixel Pg, and light of other wavelengths propagates toward the photoelectric conversion section 12 of the red pixel Pr and blue pixel Pb adjacent to the green pixel Pg. For example, of the light incident on the blue pixel Pb, blue light (B) is guided directly to the photoelectric conversion section 12 of the blue pixel Pb, and light of other wavelengths propagates toward the photoelectric conversion section 12 of the red pixel Pr and green pixel Pg adjacent to the blue pixel Pb.

The spectroscopic section 25 has a refractive index higher than that of the surrounding transparent layer 24, and for example has a refractive index of 1.7 or higher for light (incident light) incident from the light incident side S1. The spectroscopic section 25 is formed using a material having a refractive index higher than that of the transparent layer 24. The spectroscopic section 25 is formed using, for example, titanium oxide (TiO ₂ ), aluminum oxide (Al ₂ O ₃ ), silicon nitride (Si ₃ N ₄ ), amorphous silicon (α-Si), or a mixture of these materials.

The spectroscopic sections 25 provided in each of the color pixels Pr, Pg, and Pb may be formed using the same material or different materials.

On the surface of the light incident side S1 of the transparent layer 24, an on-chip lens 24L is selectively provided as a light collecting element, for example, on the blue pixel Pb. This on-chip lens 24L corresponds to one specific example of the "aperture adjustment structure" of the present disclosure. The aperture adjustment structure makes the effective pixel aperture size of a color pixel (e.g., blue pixel Pb) having a relatively low light sensitivity among the color pixels Pr, Pg, Pb provided with a spectroscopic section 25 having a predetermined diameter larger than the other color pixels (e.g., red pixel Pr and green pixel Pg). By selectively providing the on-chip lens 24L on the blue pixel Pb, the sensitivity of the blue light (B) in the blue pixel Pb is improved, and the sensitivity balance of each color pixel Pr, Pg, Pb can be adjusted.

The on-chip lens 24L may be formed using the same material as the transparent layer 24, or may be formed using a different material. In addition to the materials listed for the transparent layer 24, the on-chip lens 24L may be formed using inorganic materials such as silicon nitride (Si ₃ N ₄ ), silicon oxynitride (SiON), and amorphous silicon (α-Si). In addition, the on-chip lens 24L may be formed using an organic material with a high refractive index, such as an episulfide resin, a thietane compound, or a resin thereof. The shape of the on-chip lens 24L is not particularly limited, and various lens shapes such as a hemispherical shape or a semicylindrical shape may be adopted.

The multi-layer wiring layer 30 is provided on the side opposite to the light incident side S1 of the light receiving section 10, specifically, on the second surface 11S2 side of the semiconductor substrate 11. The multi-layer wiring layer 30 has, for example, a configuration in which a plurality of wiring layers 31, 32, and 33 are stacked with an interlayer insulating layer 34 between them. In addition to the readout circuit described above, the multi-layer wiring layer 30 also has, for example, a vertical drive circuit 111, a column signal processing circuit 112, a horizontal drive circuit 113, an output circuit 114, a control circuit 115, and an input/output terminal 116 formed therein.

The wiring layers 31, 32, and 33 are formed using, for example, aluminum (Al), copper (Cu), or tungsten (W). Alternatively, the wiring layers 31, 32, and 33 may be formed using polysilicon (Poly-Si).

The interlayer insulating layer 34 is formed of, for example, a single layer film made of one of silicon oxide (SiO _x ), TEOS, silicon nitride (SiN _x ), silicon oxynitride (SiO _x N _y ), etc., or a laminate film made of two or more of these materials.

[Action and Effects]
In the photodetector 1 of this embodiment, a wavelength separation layer 26 including, for example, one or a plurality of spectroscopic sections 25 provided planarly and discretely for each unit pixel P is provided in the transparent layer 24. An on-chip lens 24L is selectively provided on the surface of the light incident side S1 of the transparent layer 24 in a color pixel having a relatively low light sensitivity (for example, a blue pixel Pb). This improves the sensitivity of the blue pixel Pb to blue light (B). This will be described below.

In recent years, as a countermeasure against the decrease in pixel sensitivity caused by miniaturization, a technology that uses nanopost structures to scatter light and spatially separate wavelengths, thereby making the effective light-collecting area of each color larger than that of a single pixel, has been attracting attention. The nanopost structure has a high refractive index compared to the surrounding medium, and a phase difference according to the wavelength occurs between the nanopost structure and the medium. Therefore, by optimizing the radius, length, and arrangement of the nanoposts, it is possible to distribute the visible wavelength band corresponding to each color pixel that makes up the pixel unit. This makes it possible to achieve higher sensitivity than full-color image sensors that obtain RGB color information using general color filters.

However, the nanopost structure is a microstructure on the subwavelength scale (e.g., diameter of tens to hundreds of nm) relative to the wavelength of light. Therefore, in order to maximize sensitivity while also improving the sensitivity ratio of the three colors, RGB, in a well-balanced manner, precise size and position control of the nanopost structure is required, which increases the difficulty of manufacturing and increases costs.

For example, in an image sensor that uses the nanopost structure described above to improve light utilization efficiency, a nanopost with a relatively thick diameter is placed in the center of each unit pixel, and thin nanoposts with different diameters are placed at the pixel boundaries. These nanopost structures use the wavelength dependency of the phase difference generated by the nanoposts to separate the incident light into spatially different positions for each color, but the separation distance is small. Therefore, the smaller the pixel size of the CMOS image sensor, the easier it is to apply. Specifically, it is effective for fine pixels with a pixel size of 1.0 μm or less.

As an example, if one nanopost is placed in the center of a pixel of 0.8 x 0.8 μm, the spacing between adjacent nanoposts in both the row and column directions will be 0.8 μm. If a nanopost is placed between them, the spacing will be very narrow at 0.4 μm. However, since the nanoposts are isolated, they must be placed with a spacing or diameter of at least about 100 nm. Furthermore, in order to use the relative refractive index difference between the surrounding medium and the nanopost to provide a phase difference of 2 pi for the desired wavelength, the nanopost must have a certain height of about 500 nm to 1500 nm. Therefore, in the case of thin nanoposts, the aspect ratio of the diameter to the height will be large, about 1:10, which poses significant technical challenges in manufacturing.

In contrast to this, in the present embodiment, a wavelength separation layer 26 having, for example, one spectroscopic section 25 for each unit pixel P is provided as a wavelength separation structure within the transparent layer 24 provided on the first surface 11S1 side (light incident side S1) of the semiconductor substrate 11, and an on-chip lens 24L is selectively provided on the surface of the light incident side S1 of the transparent layer 24 for a color pixel with a relatively low light sensitivity (for example, a blue pixel Pb), thereby increasing the effective pixel aperture size of the blue pixel Pb.

Figure 6 is a schematic diagram of a cross-sectional configuration of a photodetector 1000A as Reference Example 1. Figure 7 is a schematic diagram of a cross-sectional configuration of a photodetector 1000B as Reference Example 2. In the photodetector 1000A, a light receiving section 1010, a light guide section 1020 provided on the light incident side S1 of the light receiving section 1010, and a multilayer wiring layer 1030 provided on the opposite side of the light incident side S1 of the light receiving section 1010 are stacked, as in the photodetector 1. The light receiving section 1010 has a semiconductor substrate 1011 having a first surface 1011S1 and a second surface 1011S2 facing each other, a plurality of photoelectric conversion sections 1012 formed by embedding the semiconductor substrate 1011, and an element isolation section 1013 provided between adjacent photoelectric conversion sections 1012. The light guide section 1020 has a color filter layer 1023 consisting of a partition wall 1021 and a color filter 1022 having color filters 1022R, 1022G, and 1022B, and on the color filter layer 1023, an on-chip lens 1024L is provided for each of the color pixels Pr, Pg, and Pb. The multilayer wiring layer 1030 has a plurality of wiring layers 1031, 1032, and 1033 stacked with an interlayer insulating layer 1034 between them. The light detection device 1000B has a transparent layer 1024 provided on the color filter layer 1023 of the light detection device 1000A, and the transparent layer 1024 has a wavelength separation structure 1026 having a spectroscopic section 1025 for each of the color pixels Pr, Pg, and Pb, similar to the light detection device 1.

Figure 8 shows the quantum efficiency of red light (R), green light (G) and blue light (B) in the photodetector 1000A. Figure 9 shows the quantum efficiency of red light (R), green light (G) and blue light (B) in the photodetector 1000B. Figure 10 shows the quantum efficiency of red light (R), green light (G) and blue light (B) in the photodetector 1. From Figures 8 and 9, by providing a wavelength separation structure 1026 having one spectroscopic section 1025 for each color pixel Pr, Pg, Pb, the sensitivity of RGB is improved, but the balance of RGB is lost. In contrast, in the photodetector 1000B, in which an on-chip lens 24L is selectively provided on the surface of the light incident side S1 of the transparent layer 24 of the blue pixel Pb, which has a relatively low light sensitivity, the quantum efficiency for blue light (B) is improved and the quantum efficiency for red light (R) is reduced, improving the RGB balance.

This allows the RGB sensitivity to be improved by a simple wavelength separation structure, while the sensitivity variations can be corrected by the simple means of selectively providing an on-chip lens 24L as an aperture adjustment structure in color pixels with relatively low light sensitivity (e.g., blue pixel Pb).

As a result, the photodetector 1 of this embodiment can improve the color balance while also increasing sensitivity.

In addition, in the photodetector 1 of this embodiment, the sensitivity is improved by a simple wavelength separation structure having, for example, one spectroscopic section 25 for each unit pixel P, and the variation in sensitivity is corrected by a simple aperture adjustment structure in which an on-chip lens 24L is selectively provided for a color pixel with a relatively low light sensitivity (for example, a blue pixel Pb). This makes it possible to reduce the difficulty and cost of manufacturing compared to an image sensor that maximizes sensitivity using only a nanopost structure while improving the balance of the sensitivity ratios of the three colors RGB.

Next, we will explain modified examples 1 to 4 and the second embodiment of the present disclosure. In the following, the same components as those in the first embodiment above will be given the same reference numerals, and their explanation will be omitted as appropriate.

2. Modified Examples
(2-1. Modification 1)
11 is a schematic diagram illustrating an example of a cross-sectional configuration of a photodetector (photodetector 1A) according to Modification 1 of the present disclosure. The photodetector 1A is, for example, a CMOS image sensor used in electronic devices such as digital still cameras and video cameras, and is, for example, a so-called back-illuminated photodetector similar to the first embodiment.

In the first embodiment described above, an example was shown in which the color balance was improved by selectively providing on-chip lenses 24L on color pixels with relatively low photosensitivity (e.g., blue pixels Pb). In contrast, in the photodetector 1A of this modified example, an inner lens layer 27 is provided between the color filter layer 23 and the transparent layer 24 instead of the on-chip lenses 24L. An inner lens 27L is provided on the surface of the inner lens layer 27 for each of the color pixels Pr, Pg, and Pb. Except for these points, the photodetector 1A has a substantially similar configuration to the photodetector 1 according to the first embodiment described above.

The inner lens layer 27 corresponds to one specific example of the "aperture adjustment structure" of the present disclosure. The inner lens layer 27 is provided, for example, so as to cover the entire surface of the pixel section 100A, and has a plurality of inner lenses 27L provided, for example, gaplessly, on its surface. The inner lenses 27L are for guiding light incident from above to the photoelectric conversion section 12, and are provided for each of the color pixels Pr, Pg, and Pb, as shown in FIG. 11.

The inner lens layer 27 including the inner lens 27L can be formed using inorganic materials such as silicon oxide (SiO ₂ ), silicon nitride (Si ₃ N ₄ ), silicon oxynitride (SiON), and amorphous silicon (α-Si). In addition, the inner lens layer 27 may be formed using organic materials with high refractive index such as episulfide resin, thietane compound, and its resin. The shape of the inner lens 27L is not particularly limited, and various lens shapes such as a hemispherical shape or a semicylindrical shape can be adopted.

In this manner, in the light detection device 1A of this modified example, an inner lens layer 27 having an inner lens 27L for each of the color pixels Pr, Pg, and Pb is provided between the color filter layer 23 and the transparent layer 24. This makes it possible to obtain the same effect as in the first embodiment.

(2-2. Modification 2)
12 is a schematic diagram illustrating an example of a cross-sectional configuration of a photodetector (photodetector 1B) according to Modification 2 of the present disclosure. The photodetector 1B is, for example, a CMOS image sensor used in electronic devices such as digital still cameras and video cameras, and is, for example, a so-called back-illuminated photodetector, similar to the first embodiment.

In the above modification 1, an example was shown in which an inner lens layer 27 having an inner lens 27L is provided for each of the color pixels Pr, Pg, and Pb. In contrast, in the photodetector 1B of this modification, an inner lens 27L is selectively provided on the surface of the inner lens layer 27 of a color pixel with a relatively low light sensitivity (e.g., blue pixel Pb). Except for these points, the photodetector 1B has a configuration substantially similar to that of the photodetector 1A according to the above modification 1.

In this manner, in the light detection device 1B of this modified example, the inner lens 27L is selectively provided on the surface of the inner lens layer 27 of a color pixel (e.g., blue pixel Pb) that has a relatively low light sensitivity. Even with this configuration, it is possible to obtain the same effect as in the first embodiment.

(2-3. Modification 3)
Fig. 13 is a schematic diagram showing an example of a cross-sectional configuration of a photodetector (photodetector 1C) according to Modification 3 of the present disclosure. Fig. 14 is a schematic diagram showing another example of a cross-sectional configuration of the photodetector 1C according to Modification 3 of the present disclosure. The photodetector 1C is, for example, a CMOS image sensor used in electronic devices such as digital still cameras and video cameras, and is, for example, a so-called back-illuminated photodetector similar to the first embodiment.

The first embodiment and the first and second modifications can be appropriately combined. That is, both the on-chip lens 24L and the inner lens 27L (inner lens layer 27) can be used as the "aperture adjustment structure" of the present disclosure. For example, as shown in FIG. 13, an inner lens layer 27 having an inner lens 27L for each of the color pixels Pr, Pg, and Pb may be provided between the color filter layer 23 and the transparent layer 24, and an on-chip lens 24L may be selectively provided for a color pixel having a relatively low light sensitivity (e.g., a blue pixel Pb). For example, as shown in FIG. 14, an inner lens layer 27 having an inner lens 27L may be selectively provided for a color pixel having a relatively low light sensitivity (e.g., a blue pixel Pb) between the color filter layer 23 and the transparent layer 24, and an on-chip lens 24L may be selectively provided for a color pixel having a relatively low light sensitivity (e.g., a blue pixel Pb).

In addition, when the on-chip lens 24L and the inner lens 27L are selectively provided to any of the color pixels Pr, Pg, and Pb, it is not necessary to provide both to the same color pixel (e.g., blue pixel Pb). For example, as shown in FIG. 15, the on-chip lens 24L may be selectively provided to the blue pixel Pb, and the inner lens 27L may be selectively provided to the red pixel Pr.

Even with this configuration, the same effects as in the first embodiment can be obtained.

(2-4. Modification 4)
16 is a schematic diagram illustrating an example of a cross-sectional configuration of a photodetector (photodetector 1D) according to Modification 4 of the present disclosure. The photodetector 1D is, for example, a CMOS image sensor used in electronic devices such as digital still cameras and video cameras, and is, for example, a so-called back-illuminated photodetector similar to the first embodiment.

In the first embodiment, an example in which one color pixel Pr, Pg, Pb is arranged in a Bayer pattern is shown, but the arrangement of each color pixel Pr, Pg, Pb in the pixel unit 100A is not limited to this. For example, a color pixel group in which multiple color pixels Pr, Pg, Pb of the same color are arranged, for example, in 2 rows x 2 columns or 3 rows x 3 columns, may be a color pixel unit (red pixel unit Ur, green pixel unit Ug, blue pixel unit Ub), and these color pixel units (red pixel unit Ur, green pixel unit Ug, blue pixel unit Ub) may be arranged in a Bayer pattern. In this case, as shown in FIG. 16, one on-chip lens 24L is arranged for the adjacent color pixel unit (for example, blue pixel unit Ub) with relatively low photosensitivity. In other words, in a photodetector 1D in which color pixel units Ur, Ug, and Ub, each of which is made up of adjacent pixels of the same color, are arranged in a Bayer pattern, one on-chip lens 24L is arranged for each color pixel unit so that it is shared by adjacent color pixels (for example, blue pixels Pb arranged adjacently in 2 rows and 2 columns).

Even with this configuration, the same effects as in the first embodiment can be obtained.

3. Second embodiment
Fig. 17 is a schematic diagram showing an example of a cross-sectional configuration of a photodetector (photodetector 2) according to a second embodiment of the present disclosure. Fig. 18 is a schematic diagram showing an example of a planar layout of the photodetector 2 shown in Fig. 17, and Fig. 17 shows a cross-sectional configuration of the photodetector 2 corresponding to line II-II' shown in Fig. 18.

The photodetector 2 of this embodiment does not have an on-chip lens 24L, and uses a color filter layer 43 as a specific example of the "aperture adjustment structure" of the present disclosure. Except for this point, the photodetector 2 has a configuration substantially similar to that of the photodetector 1 according to the first embodiment.

As in the first embodiment, the color filter layer 43 is composed of, for example, a partition wall 41 and a color filter 42.

The partition 41 is provided at the boundary between adjacent unit pixels P, and is a frame having an opening 41H for each unit pixel P. In other words, the partition 41 is provided around the unit pixel P, similar to the element isolation section 13, and is provided in a lattice pattern in the pixel section 100A. The partition 41 is intended to prevent light obliquely incident from the light incident side S1 from leaking into an adjacent unit pixel P. For example, it can be formed using a material with a lower refractive index than the color filter 42.

The partition 41 may also serve as a light shield for the unit pixel P that determines the optical black level. The partition 41 may also serve as a light shield to suppress the generation of noise in a peripheral circuit provided in the peripheral region of the pixel unit 100A. In this case, the partition 41 can be formed, for example, using a material having light shielding properties. Examples of such materials include tungsten (W), silver (Ag), copper (Cu), titanium (Ti), aluminum (Al), or alloys thereof. Other examples include metal compounds such as TiN. The partition 41 may be formed, for example, as a single layer film or a laminated film. In the case of a laminated film, for example, a layer made of Ti, tantalum (Ta), W, cobalt (Co), or molybdenum (Mo), or an alloy, nitride, oxide, or carbide thereof may be provided as an underlayer.

In this embodiment, the opening 41H of the partition 41 has a different size depending on the light sensitivity of each color pixel Pr, Pg, Pb. For example, as shown in Figures 17 and 18, the opening 41Hb of the blue pixel Pb, which has a relatively low light sensitivity, is larger than the openings 41Hr, 41Hg of the red pixel Pr and green pixel Pg, and the opening 41Hr of the red pixel Pr, which has a relatively high light sensitivity, is smaller than the openings 41Hg, 41Hb of the green pixel Pg and blue pixel Pb. In other words, the size of the openings 41Hr, 41Hg, 41Hb in each color pixel Pr, Pg, Pb is 41Hr < 41Hg < 41Hb.

The color filters 42 selectively transmit light of a predetermined wavelength, and include, for example, a red filter 42R that selectively transmits red light (R), a green filter 42G that selectively transmits green light (G), and a blue filter 42B that selectively transmits blue light (B). Each of the color filters 42R, 42G, and 42B is filled in the opening 41H of the partition wall 41. Specifically, for each of the color filters 42R, 42G, and 42B, two green filters 42G are arranged diagonally for four unit pixels P arranged in two rows and two columns, as shown in FIG. 18, and one red filter 42R and one blue filter 42B are arranged on the diagonal lines perpendicular to each other. In the unit pixel P provided with each of the color filters 42R, 42G, and 42B, for example, the corresponding color light is selectively photoelectrically converted in each photoelectric conversion unit 12.

That is, in the pixel section 100A, unit pixels P (red pixels Pr) that selectively receive and photoelectrically convert red light (R), unit pixels P (green pixels Pg) that selectively receive and photoelectrically convert green light (G), and unit pixels P (blue pixels Pb) that selectively receive and photoelectrically convert blue light (B) are arranged in a Bayer pattern. The red pixels Pr, green pixels Pg, and blue pixels Pb generate pixel signals of the red light (R) component, the green light (G) component, and the blue light (B) component, respectively. The photodetector 2 can obtain RGB pixel signals.

The color filter 42 may have filters that selectively transmit cyan, magenta, and yellow, respectively. In a unit pixel P in which each color filter 42R, 42G, and 42B is provided, for example, the corresponding color light is detected in each photoelectric conversion unit 12. The color filter 42 may be formed, for example, by dispersing a pigment or dye in a resin material. The film thickness of the color filter 42 may be different for each color, taking into account the color reproducibility and sensor sensitivity due to the spectral distribution.

In this manner, in the present embodiment, a wavelength separation layer 26 having, for example, one light-splitting section 25 is provided for each unit pixel P as a wavelength separation structure within the transparent layer 24 provided on the first surface 11S1 side (light incident side S1) of the semiconductor substrate 11, and the size of the opening 41H of the partition 41 formed for each unit pixel P in the color filter layer 43 is made larger for color pixels Pr, Pg, Pb with relatively low light sensitivity (e.g., blue pixel Pb) and smaller for color pixels with relatively high light sensitivity (e.g., red pixel Pr). This allows the sensitivity of RGB to be improved by a simple wavelength separation structure, while sensitivity variations are corrected by simple means.

As a result, the photodetector 2 of this embodiment can improve the color balance while also increasing sensitivity.

In addition, in the photodetector 2 of this embodiment, the sensitivity is improved by a simple wavelength separation structure having, for example, one spectroscopic section 25 for each unit pixel P, and the size of the opening 41H of the partition 41 formed for each unit pixel P in the color filter layer 43 is larger for color pixels Pr, Pg, Pb with relatively low light sensitivity and smaller for color pixels with relatively high light sensitivity, thereby correcting the variation in sensitivity with a simple opening adjustment structure. This makes it possible to reduce the difficulty and cost of manufacturing compared to an image sensor that maximizes sensitivity using only a nanopost structure while improving the balance of the sensitivity ratios of the three colors RGB.

4. Application Examples
(Application Example 1)
The photodetector 1 and the like can be applied to any type of electronic device equipped with an imaging function, for example, a camera system such as a digital still camera or a video camera, a mobile phone equipped with an imaging function, etc. Fig. 19 shows a schematic configuration of an electronic device 1000.

The electronic device 1000 includes, for example, a lens group 1001, a photodetector 1, a DSP (Digital Signal Processor) circuit 1002, a frame memory 1003, a display unit 1004, a recording unit 1005, an operation unit 1006, and a power supply unit 1007, which are interconnected via a bus line 1008.

The lens group 1001 captures incident light (image light) from a subject and forms an image on the imaging surface of the photodetector 1. The photodetector 1 converts the amount of incident light formed on the imaging surface by the lens group 1001 into an electrical signal on a pixel-by-pixel basis and supplies the signal as a pixel signal to the DSP circuit 1002.

The DSP circuit 1002 is a signal processing circuit that processes the signal supplied from the photodetection device 1. The DSP circuit 1002 outputs image data obtained by processing the signal from the photodetection device 1. The frame memory 1003 temporarily holds the image data processed by the DSP circuit 1002.

The display unit 1004 is, for example, a panel-type display device such as a liquid crystal panel or an organic EL (Electro Luminescence) panel, and records the image data of moving images or still images captured by the light detection device 1 on a recording medium such as a semiconductor memory or a hard disk.

The operation unit 1006 outputs operation signals for various functions of the electronic device 1000 in accordance with operations by the user. The power supply unit 1007 appropriately supplies various types of power to the DSP circuit 1002, frame memory 1003, display unit 1004, recording unit 1005, and operation unit 1006 to these power sources.

(Application Example 2)
Fig. 20A is a schematic diagram showing an example of the overall configuration of a light detection system 2000 including a light detection device 1. Fig. 20B is a diagram showing an example of the circuit configuration of the light detection system 2000. The light detection system 2000 includes a light emitting device 2001 as a light source unit that emits infrared light L2, and a light detection device 2002 as a light receiving unit having a photoelectric conversion element. The light detection device 1 described above can be used as the light detection device 2002. The light detection system 2000 may further include a system control unit 2003, a light source driving unit 2004, a sensor control unit 2005, a light source side optical system 2006, and a camera side optical system 2007.

The light detection device 2002 can detect light L1 and light L2. Light L1 is external ambient light reflected by the subject (measurement object) 2100 (FIG. 20A). Light L2 is light emitted by the light emitting device 2001 and then reflected by the subject 2100. Light L1 is, for example, visible light, and light L2 is, for example, infrared light. Light L1 can be detected by the photoelectric conversion unit in the light detection device 2002, and light L2 can be detected by the photoelectric conversion region in the light detection device 2002. Image information of the subject 2100 can be obtained from the light L1, and distance information between the subject 2100 and the light detection system 2000 can be obtained from the light L2. The light detection system 2000 can be mounted on, for example, an electronic device such as a smartphone or a moving object such as a car. The light emitting device 2001 can be configured, for example, by a semiconductor laser, a surface-emitting semiconductor laser, or a vertical-cavity surface-emitting laser (VCSEL). The detection method of the light L2 emitted from the light emitting device 2001 by the light detection device 2002 may be, for example, an iTOF method, but is not limited thereto. In the iTOF method, the photoelectric conversion unit can measure the distance to the subject 2100 by, for example, the time-of-flight (TOF). The detection method of the light L2 emitted from the light emitting device 2001 by the light detection device 2002 may be, for example, a structured light method or a stereo vision method. For example, in the structured light method, a predetermined pattern of light is projected onto the subject 2100, and the distance between the light detection system 2000 and the subject 2100 can be measured by analyzing the degree of distortion of the pattern. In addition, in the stereo vision method, for example, two or more cameras are used to obtain two or more images of the subject 2100 viewed from two or more different viewpoints, thereby measuring the distance between the light detection system 2000 and the subject. The light emitting device 2001 and the light detection device 2002 can be synchronously controlled by the system control unit 2003.

<5. Application Examples>
(Application example to endoscopic surgery system)
The technology according to the present disclosure (the present technology) can be applied to various products. For example, the technology according to the present disclosure may be applied to an endoscopic surgery system.

Figure 21 is a diagram showing an example of the general configuration of an endoscopic surgery system to which the technology disclosed herein (the present technology) can be applied.

Figure 21 shows an operator (doctor) 11131 performing surgery on a patient 11132 on a patient bed 11133 using an endoscopic surgery system 11000. As shown in the figure, the endoscopic surgery system 11000 is composed of an endoscope 11100, other surgical tools 11110 such as an insufflation tube 11111 and an energy treatment tool 11112, a support arm device 11120 that supports the endoscope 11100, and a cart 11200 on which various devices for endoscopic surgery are mounted.

The endoscope 11100 is composed of a lens barrel 11101, the tip of which is inserted into the body cavity of the patient 11132 at a predetermined length, and a camera head 11102 connected to the base end of the lens barrel 11101. In the illustrated example, the endoscope 11100 is configured as a so-called rigid scope having a rigid lens barrel 11101, but the endoscope 11100 may also be configured as a so-called flexible scope having a flexible lens barrel.

The endoscope 11100 has an opening at the tip of the tube 11101 into which an objective lens is fitted. A light source device 11203 is connected to the endoscope 11100, and light generated by the light source device 11203 is guided to the tip of the tube by a light guide extending inside the tube 11101, and is irradiated via the objective lens toward an object to be observed inside the body cavity of the patient 11132. The endoscope 11100 may be a direct-viewing endoscope, an oblique-viewing endoscope, or a side-viewing endoscope.

An optical system and an image sensor are provided inside the camera head 11102, and reflected light (observation light) from the object being observed is focused onto the image sensor by the optical system. The observation light is photoelectrically converted by the image sensor to generate an electrical signal corresponding to the observation light, i.e., an image signal corresponding to the observed image. The image signal is sent to the camera control unit (CCU) 11201 as RAW data.

The CCU 11201 is configured with a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), etc., and performs overall control of the operations of the endoscope 11100 and the display device 11202. Furthermore, the CCU 11201 receives an image signal from the camera head 11102, and performs various types of image processing on the image signal, such as development processing (demosaic processing), for displaying an image based on the image signal.

Under the control of the CCU 11201, the display device 11202 displays an image based on an image signal that has been subjected to image processing by the CCU 11201.

The light source device 11203 is composed of a light source such as an LED (light emitting diode) and supplies illumination light to the endoscope 11100 when photographing the surgical site, etc.

The input device 11204 is an input interface for the endoscopic surgery system 11000. A user can input various information and instructions to the endoscopic surgery system 11000 via the input device 11204. For example, the user inputs an instruction to change the imaging conditions (type of irradiation light, magnification, focal length, etc.) of the endoscope 11100.

The treatment tool control device 11205 controls the operation of the energy treatment tool 11112 for cauterizing tissue, incising, sealing blood vessels, etc. The insufflation device 11206 sends gas into the body cavity of the patient 11132 via the insufflation tube 11111 to inflate the body cavity in order to ensure a clear field of view for the endoscope 11100 and to ensure a working space for the surgeon. The recorder 11207 is a device capable of recording various types of information related to the surgery. The printer 11208 is a device capable of printing various types of information related to the surgery in various formats such as text, images, or graphs.

The light source device 11203 that supplies irradiation light to the endoscope 11100 when photographing the surgical site can be composed of a white light source composed of, for example, an LED, a laser light source, or a combination of these. When the white light source is composed of a combination of RGB laser light sources, the output intensity and output timing of each color (each wavelength) can be controlled with high precision, so that the white balance of the captured image can be adjusted in the light source device 11203. In this case, it is also possible to capture images corresponding to each of the RGB colors in a time-division manner by irradiating the observation object with laser light from each of the RGB laser light sources in a time-division manner and controlling the drive of the image sensor of the camera head 11102 in synchronization with the irradiation timing. According to this method, a color image can be obtained without providing a color filter to the image sensor.

The light source device 11203 may be controlled to change the intensity of the light it outputs at predetermined time intervals. The image sensor of the camera head 11102 may be controlled to acquire images in a time-division manner in synchronization with the timing of the change in the light intensity, and the images may be synthesized to generate an image with a high dynamic range that is free of so-called blackout and whiteout.

The light source device 11203 may be configured to supply light in a predetermined wavelength range corresponding to the special light observation. In the special light observation, for example, by utilizing the wavelength dependency of light absorption in body tissue, a narrow band light is irradiated compared to the irradiation light (i.e., white light) during normal observation, and a predetermined tissue such as blood vessels on the mucosal surface is photographed with high contrast, so-called narrow band imaging is performed. Alternatively, in the special light observation, a fluorescent observation may be performed in which an image is obtained by fluorescence generated by irradiating an excitation light. In the fluorescent observation, an excitation light is irradiated to a body tissue and the fluorescence from the body tissue is observed (autofluorescence observation), or a reagent such as indocyanine green (ICG) is locally injected into the body tissue and an excitation light corresponding to the fluorescent wavelength of the reagent is irradiated to the body tissue to obtain a fluorescent image. The light source device 11203 may be configured to supply narrow band light and/or excitation light corresponding to such special light observation.

Figure 22 is a block diagram showing an example of the functional configuration of the camera head 11102 and CCU 11201 shown in Figure 21.

The camera head 11102 has a lens unit 11401, an imaging unit 11402, a drive unit 11403, a communication unit 11404, and a camera head control unit 11405. The CCU 11201 has a communication unit 11411, an image processing unit 11412, and a control unit 11413. The camera head 11102 and the CCU 11201 are connected to each other via a transmission cable 11400 so that they can communicate with each other.

The lens unit 11401 is an optical system provided at the connection with the lens barrel 11101. Observation light taken in from the tip of the lens barrel 11101 is guided to the camera head 11102 and enters the lens unit 11401. The lens unit 11401 is composed of a combination of multiple lenses including a zoom lens and a focus lens.

The imaging element constituting the imaging unit 11402 may be one (so-called single-plate type) or multiple (so-called multi-plate type). When the imaging unit 11402 is configured as a multi-plate type, for example, each imaging element may generate an image signal corresponding to each of RGB, and a color image may be obtained by combining them. Alternatively, the imaging unit 11402 may be configured to have a pair of imaging elements for acquiring image signals for the right eye and the left eye corresponding to 3D (dimensional) display. By performing 3D display, the surgeon 11131 can more accurately grasp the depth of the biological tissue in the surgical site. In addition, when the imaging unit 11402 is configured as a multi-plate type, the lens unit 11401 may also be provided in multiple systems corresponding to each imaging element.

Furthermore, the imaging unit 11402 does not necessarily have to be provided in the camera head 11102. For example, the imaging unit 11402 may be provided inside the lens barrel 11101, immediately after the objective lens.

The drive unit 11403 is composed of an actuator, and moves the zoom lens and focus lens of the lens unit 11401 a predetermined distance along the optical axis under the control of the camera head control unit 11405. This allows the magnification and focus of the image captured by the imaging unit 11402 to be appropriately adjusted.

The communication unit 11404 is configured with a communication device for transmitting and receiving various information to and from the CCU 11201. The communication unit 11404 transmits the image signal obtained from the imaging unit 11402 as RAW data to the CCU 11201 via the transmission cable 11400.

The communication unit 11404 also receives control signals for controlling the operation of the camera head 11102 from the CCU 11201 and supplies them to the camera head control unit 11405. The control signals include information on the imaging conditions, such as information specifying the frame rate of the captured image, information specifying the exposure value during imaging, and/or information specifying the magnification and focus of the captured image.

The above-mentioned frame rate, exposure value, magnification, focus, and other imaging conditions may be appropriately specified by the user, or may be automatically set by the control unit 11413 of the CCU 11201 based on the acquired image signal. In the latter case, the endoscope 11100 is equipped with so-called AE (Auto Exposure) function, AF (Auto Focus) function, and AWB (Auto White Balance) function.

The camera head control unit 11405 controls the operation of the camera head 11102 based on a control signal from the CCU 11201 received via the communication unit 11404.

The communication unit 11411 is configured with a communication device for transmitting and receiving various information to and from the camera head 11102. The communication unit 11411 receives an image signal transmitted from the camera head 11102 via the transmission cable 11400.

The communication unit 11411 also transmits a control signal to the camera head 11102 for controlling the driving of the camera head 11102. The image signal and the control signal can be transmitted by electrical communication, optical communication, etc.

The image processing unit 11412 performs various image processing operations on the image signal, which is the RAW data transmitted from the camera head 11102.

The control unit 11413 performs various controls related to the imaging of the surgical site, etc. by the endoscope 11100, and the display of the captured images obtained by imaging the surgical site, etc. For example, the control unit 11413 generates a control signal for controlling the driving of the camera head 11102.

The control unit 11413 also displays the captured image showing the surgical site on the display device 11202 based on the image signal that has been image-processed by the image processing unit 11412. At this time, the control unit 11413 may recognize various objects in the captured image using various image recognition techniques. For example, the control unit 11413 can recognize surgical tools such as forceps, specific body parts, bleeding, mist generated when using the energy treatment tool 11112, and the like, by detecting the shape and color of the edges of objects included in the captured image. When the control unit 11413 displays the captured image on the display device 11202, it may use the recognition result to superimpose various types of surgical support information on the image of the surgical site. By superimposing the surgical support information and presenting it to the surgeon 11131, the burden on the surgeon 11131 can be reduced and the surgeon 11131 can proceed with the surgery reliably.

The transmission cable 11400 connecting the camera head 11102 and the CCU 11201 is an electrical signal cable for electrical signal communication, an optical fiber for optical communication, or a composite cable of these.

In the illustrated example, communication is performed wired using a transmission cable 11400, but communication between the camera head 11102 and the CCU 11201 may also be performed wirelessly.

An example of an endoscopic surgery system to which the technology disclosed herein can be applied has been described above. The technology disclosed herein can be applied to the imaging unit 11402 of the configuration described above. By applying the technology disclosed herein to the imaging unit 11402, detection accuracy is improved.

Note that, although an endoscopic surgery system has been described here as an example, the technology disclosed herein may also be applied to other systems, such as a microsurgery system.

(Example of application to moving objects)
The technology according to the present disclosure can be applied to various products. For example, the technology according to the present disclosure may be realized as a device mounted on any type of moving body, such as an automobile, an electric vehicle, a hybrid electric vehicle, a motorcycle, a bicycle, a personal mobility device, an airplane, a drone, a ship, a robot, a construction machine, or an agricultural machine (tractor).

Figure 23 is a block diagram showing a schematic configuration example of a vehicle control system, which is an example of a mobile object control system to which the technology disclosed herein can be applied.

The vehicle control system 12000 includes a plurality of electronic control units connected via a communication network 12001. In the example shown in FIG. 23, the vehicle control system 12000 includes a drive system control unit 12010, a body system control unit 12020, an outside vehicle information detection unit 12030, an inside vehicle information detection unit 12040, and an integrated control unit 12050. In addition, the functional configuration of the integrated control unit 12050 includes a microcomputer 12051, an audio/video output unit 12052, and an in-vehicle network I/F (interface) 12053.

The drive system control unit 12010 controls the operation of devices related to the drive system of the vehicle according to various programs. For example, the drive system control unit 12010 functions as a control device for a drive force generating device for generating a drive force for the vehicle, such as an internal combustion engine or a drive motor, a drive force transmission mechanism for transmitting the drive force to the wheels, a steering mechanism for adjusting the steering angle of the vehicle, and a braking device for generating a braking force for the vehicle.

The body system control unit 12020 controls the operation of various devices installed in the vehicle body according to various programs. For example, the body system control unit 12020 functions as a control device for a keyless entry system, a smart key system, a power window device, or various lamps such as headlamps, tail lamps, brake lamps, turn signals, and fog lamps. In this case, radio waves or signals from various switches transmitted from a portable device that replaces a key can be input to the body system control unit 12020. The body system control unit 12020 receives these radio waves or signal inputs and controls the vehicle's door lock device, power window device, lamps, etc.

The outside-vehicle information detection unit 12030 detects information outside the vehicle equipped with the vehicle control system 12000. For example, the image capturing unit 12031 is connected to the outside-vehicle information detection unit 12030. The outside-vehicle information detection unit 12030 causes the image capturing unit 12031 to capture images outside the vehicle and receives the captured images. The outside-vehicle information detection unit 12030 may perform object detection processing or distance detection processing for people, cars, obstacles, signs, or characters on the road surface based on the received images.

The imaging unit 12031 is an optical sensor that receives light and outputs an electrical signal according to the amount of light received. The imaging unit 12031 can output the electrical signal as an image, or as distance measurement information. The light received by the imaging unit 12031 may be visible light, or may be invisible light such as infrared light.

The in-vehicle information detection unit 12040 detects information inside the vehicle. For example, a driver state detection unit 12041 that detects the state of the driver is connected to the in-vehicle information detection unit 12040. The driver state detection unit 12041 includes, for example, a camera that captures an image of the driver, and the in-vehicle information detection unit 12040 may calculate the driver's degree of fatigue or concentration based on the detection information input from the driver state detection unit 12041, or may determine whether the driver is dozing off.

The microcomputer 12051 can calculate the control target values of the driving force generating device, steering mechanism, or braking device based on the information inside and outside the vehicle acquired by the outside vehicle information detection unit 12030 or the inside vehicle information detection unit 12040, and output a control command to the drive system control unit 12010. For example, the microcomputer 12051 can perform cooperative control aimed at realizing the functions of an ADAS (Advanced Driver Assistance System), including avoiding or mitigating vehicle collisions, following based on the distance between vehicles, maintaining vehicle speed, vehicle collision warning, or vehicle lane departure warning.

The microcomputer 12051 can also perform cooperative control for the purpose of autonomous driving, which allows the vehicle to travel autonomously without relying on the driver's operation, by controlling the driving force generating device, steering mechanism, braking device, etc. based on information about the surroundings of the vehicle acquired by the outside vehicle information detection unit 12030 or the inside vehicle information detection unit 12040.

The microcomputer 12051 can also output control commands to the body system control unit 12020 based on information outside the vehicle acquired by the outside-vehicle information detection unit 12030. For example, the microcomputer 12051 can control the headlamps according to the position of a preceding vehicle or an oncoming vehicle detected by the outside-vehicle information detection unit 12030, and perform cooperative control aimed at preventing glare, such as switching high beams to low beams.

The audio/image output unit 12052 transmits at least one output signal of audio and image to an output device capable of visually or audibly notifying information to vehicle occupants or the outside of the vehicle. In the example of FIG. 23, an audio speaker 12061, a display unit 12062, and an instrument panel 12063 are exemplified as output devices. The display unit 12062 may include, for example, at least one of an on-board display and a head-up display.

Figure 24 shows an example of the installation position of the imaging unit 12031.

In FIG. 24, the imaging unit 12031 includes imaging units 12101, 12102, 12103, 12104, and 12105.

The imaging units 12101, 12102, 12103, 12104, and 12105 are provided, for example, at the front nose, side mirrors, rear bumper, back door, and upper part of the windshield inside the vehicle cabin of the vehicle 12100. The imaging unit 12101 provided at the front nose and the imaging unit 12105 provided at the upper part of the windshield inside the vehicle cabin mainly acquire images of the front of the vehicle 12100. The imaging units 12102 and 12103 provided at the side mirrors mainly acquire images of the sides of the vehicle 12100. The imaging unit 12104 provided at the rear bumper or back door mainly acquires images of the rear of the vehicle 12100. The imaging unit 12105 provided at the upper part of the windshield inside the vehicle cabin is mainly used to detect leading vehicles, pedestrians, obstacles, traffic lights, traffic signs, lanes, etc.

In addition, FIG. 24 shows an example of the imaging ranges of the imaging units 12101 to 12104. Imaging range 12111 indicates the imaging range of the imaging unit 12101 provided on the front nose, imaging ranges 12112 and 12113 indicate the imaging ranges of the imaging units 12102 and 12103 provided on the side mirrors, respectively, and imaging range 12114 indicates the imaging range of the imaging unit 12104 provided on the rear bumper or back door. For example, an overhead image of the vehicle 12100 viewed from above is obtained by superimposing the image data captured by the imaging units 12101 to 12104.

At least one of the imaging units 12101 to 12104 may have a function of acquiring distance information. For example, at least one of the imaging units 12101 to 12104 may be a stereo camera consisting of multiple imaging elements, or may be an imaging element having pixels for phase difference detection.

For example, the microcomputer 12051 can extract, as a preceding vehicle, the closest three-dimensional object on the path of the vehicle 12100 that is traveling in approximately the same direction as the vehicle 12100 at a predetermined speed (e.g., 0 km/h or faster) by calculating the distance to each three-dimensional object within the imaging range 12111 to 12114 and the change in this distance over time (relative speed with respect to the vehicle 12100) based on the distance information obtained from the imaging units 12101 to 12104. Furthermore, the microcomputer 12051 can set the distance to be secured in advance in front of the preceding vehicle, and perform automatic brake control (including follow-up stop control) and automatic acceleration control (including follow-up start control). In this way, cooperative control can be performed for the purpose of autonomous driving, which runs autonomously without relying on the driver's operation.

For example, the microcomputer 12051 classifies and extracts three-dimensional object data on three-dimensional objects, such as two-wheeled vehicles, ordinary vehicles, large vehicles, pedestrians, utility poles, and other three-dimensional objects, based on the distance information obtained from the imaging units 12101 to 12104, and can use the data to automatically avoid obstacles. For example, the microcomputer 12051 distinguishes obstacles around the vehicle 12100 into obstacles that are visible to the driver of the vehicle 12100 and obstacles that are difficult to see. Then, the microcomputer 12051 determines the collision risk, which indicates the risk of collision with each obstacle, and when the collision risk is equal to or exceeds a set value and there is a possibility of a collision, the microcomputer 12051 can provide driving assistance for collision avoidance by outputting an alarm to the driver via the audio speaker 12061 or the display unit 12062, or by performing forced deceleration or avoidance steering via the drive system control unit 12010.

At least one of the imaging units 12101 to 12104 may be an infrared camera that detects infrared rays. For example, the microcomputer 12051 can recognize a pedestrian by determining whether or not a pedestrian is present in the captured images of the imaging units 12101 to 12104. The recognition of such a pedestrian is performed, for example, by a procedure of extracting feature points in the captured images of the imaging units 12101 to 12104 as infrared cameras, and a procedure of performing pattern matching processing on a series of feature points that indicate the contour of an object to determine whether or not the object is a pedestrian. When the microcomputer 12051 determines that a pedestrian is present in the captured images of the imaging units 12101 to 12104 and recognizes the pedestrian, the audio/image output unit 12052 controls the display unit 12062 to superimpose a rectangular contour line for emphasis on the recognized pedestrian. The audio/image output unit 12052 may also control the display unit 12062 to display an icon or the like indicating a pedestrian at a desired position.

An example of a mobile object control system to which the technology according to the present disclosure can be applied has been described above. The technology according to the present disclosure can be applied to the imaging unit 12031 of the configuration described above. Specifically, the light detection devices according to the first and second embodiments and their modifications 1 to 4 (e.g., light detection device 1) can be applied to the imaging unit 12031. By applying the technology according to the present disclosure to the imaging unit 12031, a high-definition captured image with little noise can be obtained, and therefore high-precision control using the captured image can be performed in the mobile object control system.

Although the present disclosure has been described above with reference to the first and second embodiments, modifications 1 to 4, and application examples, the present technology is not limited to the above-mentioned embodiments, and various modifications are possible. For example, modifications 1 to 4 described above have been described as modifications of the first embodiment, but the configurations of each modification and the second embodiment can be appropriately combined. For example, the "aperture adjustment structure" of the present disclosure may be configured by combining the color filter layer 23 with the on-chip lens 24L or the inner lens 27L.

Note that the effects described in this specification are merely examples and are not limited to those described, and other effects may also be present.

The present disclosure may also be configured as follows. According to the present technology having the following configuration, the quantum efficiency of pixels having relatively low light sensitivity is improved. This makes it possible to improve the color balance as well as the sensitivity.
(1)
a semiconductor substrate having a first surface and a second surface opposed to each other, and a plurality of first pixels and second pixels that selectively perform photoelectric conversion on wavelengths different from each other and are arranged in a matrix;
a wavelength separation structure in which media having mutually different refractive indices are provided planarly and discretely on the first surface side of the first pixel and the second pixel, the first pixel separates incident light into a first wavelength component and other wavelength components and selectively guides the first wavelength component to the first pixel, and the second pixel separates incident light into a second wavelength component and other wavelength components and selectively guides the second wavelength component to the second pixel;
an aperture adjustment structure provided on the first surface side and configured to make an effective pixel aperture size of one of the first pixels and the second pixels, which has a relatively low light sensitivity, larger than that of the other pixel.
(2)
the wavelength separation structure includes a first medium formed as a common layer for the first pixel and the second pixel, and a second medium provided in each of the first pixel and the second pixel;
The optical detection device according to (1), wherein the second medium has a columnar structure having a size equal to or smaller than a predetermined wavelength of the incident light and has a refractive index higher than that of the first medium.
(3)
The photodetector according to (2), wherein the second medium is provided in one or more of the first pixel and the second pixel, and has a different diameter in the first pixel and the second pixel.
(4)
The optical detection device according to (2) or (3), wherein the first medium has a refractive index of 1.5 or less for the incident light.
(5)
The optical detection device according to any one of (2) to (4), wherein the first medium is made of silicon oxide, silicon oxide doped with fluorine, fluororesin, porous silica, or a mixture of these materials.
(6)
The optical detection device according to any one of (2) to (5), wherein the second medium has a refractive index of 1.7 or more for the incident light.
(7)
The optical detection device according to any one of (2) to (6), wherein the second medium is made of titanium oxide, aluminum oxide, silicon nitride, amorphous silicon, or a mixture thereof.
(8)
The light detection device according to any one of (1) to (7), wherein the aperture adjustment structure is composed of a light-collecting element selectively provided in the one pixel.
(9)
The photodetector according to (8), wherein the light-collecting element is an on-chip lens that is arranged on the light incident side of the wavelength separation structure.
(10)
The optical detection device according to (8) or (9), wherein the light-collecting element is an inner lens disposed between the first surface and the wavelength separation structure.
(11)
the first pixels and the second pixels are arranged adjacent to each other in a row direction and a column direction on the semiconductor substrate,
The optical detection device according to any one of (8) to (10), wherein the light-collecting elements are provided in one of a first pixel group consisting of a plurality of adjacently arranged first pixels or a second pixel group consisting of a plurality of adjacently arranged second pixels, whichever has a relatively lower optical sensitivity.
(12)
the aperture adjustment structure is provided at a boundary between the first pixel and the second pixel adjacent to each other between the first surface and the wavelength separation structure, and is composed of a frame having an aperture in each of the first pixel and the second pixel;
an aperture size of the one pixel is larger than an aperture size of the other pixel,
The light detection device described in any one of (1) to (11), wherein the openings are filled with color filters that selectively transmit wavelengths that are photoelectrically converted in the first pixel and the second pixel, respectively.
(13)
The light detection device according to (12), wherein the frame is made of a material having a lower refractive index than the color filter.
(14)
a semiconductor substrate having a first surface and a second surface opposed to each other, the semiconductor substrate having a plurality of first pixels and second pixels arranged in a matrix, the first pixels and second pixels selectively performing photoelectric conversion on wavelengths different from each other;
a wavelength separation structure in which media having mutually different refractive indices are provided planarly and discretely on the first surface side of the first pixel and the second pixel, the first pixel separates incident light into a first wavelength component and other wavelength components and selectively guides the first wavelength component to the first pixel, and the second pixel separates incident light into a second wavelength component and other wavelength components and selectively guides the second wavelength component to the second pixel;
a light-collecting element provided on the first surface side in a pixel having a relatively low light sensitivity out of the first pixels and the second pixels.
(15)
The photodetector according to (14), wherein the light-collecting element is an on-chip lens arranged on the light incident side of the wavelength separation structure.
(16)
The optical detection device according to (14) or (15), wherein the light-collecting element is an inner lens disposed between the first surface and the wavelength separation structure.
(17)
a semiconductor substrate having a first surface and a second surface opposed to each other, and a plurality of first pixels and second pixels that selectively perform photoelectric conversion on wavelengths different from each other and are arranged in a matrix;
a wavelength separation structure in which media having mutually different refractive indices are provided planarly and discretely on the first surface side of the first pixel and the second pixel, the first pixel separates incident light into a first wavelength component and other wavelength components and selectively guides the first wavelength component to the first pixel, and the second pixel separates incident light into a second wavelength component and other wavelength components and selectively guides the second wavelength component to the second pixel;
a frame body provided at a boundary between the first pixel and the second pixel adjacent to each other between the first surface and the wavelength separation structure, the frame body having an opening at each of the first pixel and the second pixel, and a color filter layer including a color filter filled in the opening and selectively transmitting a wavelength that is photoelectrically converted in each of the first pixel and the second pixel;
The size of the aperture of a pixel having a relatively low light sensitivity is larger than the size of the aperture of other pixels.
(18)
The light detection device according to (17), wherein the frame is made of a material having a lower refractive index than the color filter.

1, 1A, 1B, 1C, 1D, 2...photodetector, 10...light-receiving section, 11...semiconductor substrate, 12...photoelectric conversion section, 13...element isolation section, 14...fixed charge layer, 20...light-guiding section, 21...partition, 22...color filter, 22B...blue filter, 33G...green filter, 22R...red filter, 23...color filter layer, 24...transparent layer, 24L...on-chip lens, 25...spectroscopic section, 26...wavelength separation layer, 27...inner lens layer, 27L...inner lens, 30...multilayer wiring layer, 31, 32, 33...wiring layer, 34...interlayer insulating layer, 11S1...first surface, 11S2...second surface, S1...light incident side.

Claims (18)

a semiconductor substrate having a first surface and a second surface opposed to each other, the semiconductor substrate having a plurality of first pixels and second pixels arranged in a matrix, the first pixels and second pixels selectively performing photoelectric conversion on wavelengths different from each other;
a wavelength separation structure in which media having mutually different refractive indices are provided planarly and discretely on the first surface side of the first pixel and the second pixel, the first pixel separates incident light into a first wavelength component and other wavelength components and selectively guides the first wavelength component to the first pixel, and the second pixel separates incident light into a second wavelength component and other wavelength components and selectively guides the second wavelength component to the second pixel;
an aperture adjustment structure provided on the first surface side and configured to make an effective pixel aperture size of one of the first pixels and the second pixels, which has a relatively low light sensitivity, larger than that of the other pixel. the wavelength separation structure includes a first medium formed as a common layer for the first pixel and the second pixel, and a second medium provided in each of the first pixel and the second pixel;
2. The optical detection device according to claim 1, wherein the second medium has a columnar structure having a size equal to or smaller than a predetermined wavelength of the incident light, and has a refractive index higher than that of the first medium. The photodetector according to claim 2, wherein one or more second media are provided for each of the first pixel and the second pixel, and the first pixel and the second pixel have different diameters. The optical detection device according to claim 2, wherein the first medium has a refractive index of 1.5 or less for the incident light. The optical detection device according to claim 2, wherein the first medium is made of silicon oxide, silicon oxide doped with fluorine, fluororesin, porous silica, or a mixture of these materials. The optical detection device according to claim 2, wherein the second medium has a refractive index of 1.7 or more for the incident light. The optical detection device according to claim 2, wherein the second medium is made of titanium oxide, aluminum oxide, silicon nitride, amorphous silicon, or a mixture thereof. The optical detection device according to claim 1, wherein the aperture adjustment structure is composed of a light-collecting element selectively provided in one of the pixels. The optical detection device according to claim 8, wherein the light-collecting element is an on-chip lens arranged on the light-incident side of the wavelength separation structure. The optical detection device according to claim 8, wherein the focusing element is an inner lens disposed between the first surface and the wavelength separation structure. the first pixels and the second pixels are arranged adjacent to each other in a row direction and a column direction on the semiconductor substrate,
9. The photodetection device according to claim 8, wherein the light-collecting elements are provided in one pixel group having a relatively lower light sensitivity out of a first pixel group consisting of a plurality of the first pixels arranged adjacent to each other or a second pixel group consisting of a plurality of the second pixels arranged adjacent to each other. the aperture adjustment structure is provided at a boundary between the first pixel and the second pixel adjacent to each other between the first surface and the wavelength separation structure, and is composed of a frame having an aperture in each of the first pixel and the second pixel;
an aperture size of the one pixel is larger than an aperture size of the other pixel,
The photodetector according to claim 1 , wherein the openings are filled with color filters that selectively transmit wavelengths that are photoelectrically converted in the first pixel and the second pixel, respectively. The light detection device according to claim 12, wherein the frame is made of a material having a lower refractive index than the color filter. a semiconductor substrate having a first surface and a second surface opposed to each other, the semiconductor substrate having a plurality of first pixels and second pixels arranged in a matrix, the first pixels and second pixels selectively performing photoelectric conversion on wavelengths different from each other;
a wavelength separation structure in which media having mutually different refractive indices are provided planarly and discretely on the first surface side of the first pixel and the second pixel, the first pixel separates incident light into a first wavelength component and other wavelength components and selectively guides the first wavelength component to the first pixel, and the second pixel separates incident light into a second wavelength component and other wavelength components and selectively guides the second wavelength component to the second pixel;
a light-collecting element provided on the first surface side in a pixel having a relatively low light sensitivity out of the first pixels and the second pixels. The optical detection device according to claim 14, wherein the light-collecting element is an on-chip lens arranged on the light-incident side of the wavelength separation structure. The optical detection device according to claim 14, wherein the focusing element is an inner lens disposed between the first surface and the wavelength separation structure. a semiconductor substrate having a first surface and a second surface opposed to each other, the semiconductor substrate having a plurality of first pixels and second pixels arranged in a matrix, the first pixels and second pixels selectively performing photoelectric conversion on wavelengths different from each other;
a wavelength separation structure in which media having mutually different refractive indices are provided planarly and discretely on the first surface side of the first pixel and the second pixel, the first pixel separates incident light into a first wavelength component and other wavelength components and selectively guides the first wavelength component to the first pixel, and the second pixel separates incident light into a second wavelength component and other wavelength components and selectively guides the second wavelength component to the second pixel;
a frame body provided at a boundary between the first pixel and the second pixel adjacent to each other between the first surface and the wavelength separation structure, the frame body having an opening at each of the first pixel and the second pixel, and a color filter layer including a color filter filled in the opening and selectively transmitting a wavelength that is photoelectrically converted in each of the first pixel and the second pixel;
The size of the aperture of a pixel having a relatively low light sensitivity is larger than the size of the aperture of other pixels. The light detection device according to claim 17 , wherein the frame is made of a material having a refractive index lower than that of the color filter.

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