Light detection device and electronic equipment

Abstract

[Problem] To provide a light detection device capable of achieving improved optical characteristics related to light reception of color light. [Solution] A light detection device according to an embodiment of the present disclosure comprises: a lens on which light is incident; a color filter that transmits specific color light included in the light transmitted through the lens; and a photoelectric conversion element that photoelectrically converts the specific color light received via the color filter. The color filter has a first portion having a first refractive index and a second portion having a second refractive index different from the first refractive index.

Description

Photodetector and electronic equipment

[0001] The present disclosure relates to photodetection devices and electronic equipment.

[0002] A CMOS (Complementary Metal Oxide Semiconductor) image sensor is known as a photodetector device, and includes a color filter that transmits specific colored light. In such a CMOS image sensor, the colored light transmitted through the color filter is received by a photoelectric conversion element. The photoelectric conversion element photoelectrically converts the received colored light.

[0003] International Publication No. 2019 / 124562

[0004] In a photodetection device in which pixels receive colored light through color filters, there is a demand for improvements in optical characteristics relating to the reception of colored light.

[0005] The present disclosure provides a photodetector and an electronic device that can improve optical characteristics related to receiving colored light.

[0006] A photodetector according to an embodiment of the present disclosure includes a lens onto which light is incident, a color filter that transmits specific colored light included in the light that has passed through the lens, and a photoelectric conversion element that photoelectrically converts the specific colored light received through the color filter, wherein the color filter has a first portion having a first refractive index and a second portion having a second refractive index different from the first refractive index.

[0007] The photoelectric conversion element may include: a first photoelectric conversion element; and a second photoelectric conversion element arranged alongside the first photoelectric conversion element and performing photoelectric conversion on color light of the same color as that of the first photoelectric conversion element.

[0008] The second portion may be a hemisphere.

[0009] The second portion may be a box-shaped body.

[0010] The second portion may be a diffraction grating.

[0011] The second portion may be a convex block.

[0012] The first portion and the second portion may be box-shaped bodies arranged side by side.

[0013] The second portion may be composed of a plurality of pillars having different widths, and the height of each of the plurality of pillars may be smaller than the wavelength of the colored light.

[0014] The first portion may also be composed of a plurality of pillars having different widths, and the pillars constituting the first portion and the pillars constituting the second portion may be arranged alternately.

[0015] The second portion may be a rod-shaped body provided in the center of the color filter, and the first portion may be an annular body surrounding the first portion.

[0016] The second portion may be a concave body.

[0017] The color filter may be a laminate in which the first portion is laminated between two of the second portions.

[0018] The color filter may be a laminate in which at least one portion having a third refractive index higher than the first refractive index and lower than the second refractive index is laminated between the first portion and the second portion.

[0019] One color filter may be provided for each of the first photoelectric conversion elements and the second photoelectric conversion elements.

[0020] The material of the first portion may be the same as the material of the second portion, and the concentration of the material of the first portion may be different from the concentration of the material of the second portion.

[0021] The first portion may be made of a material having the first refractive index, and the second portion may be made of a material having the second refractive index.

[0022] According to an embodiment of the present disclosure, an electronic device includes a light detection device having a lens onto which light is incident, a color filter that transmits specific color light contained in the light that has passed through the lens, and a photoelectric conversion element that photoelectrically converts the specific color light received through the color filter, wherein the color filter has a first portion having a first refractive index and a second portion having a second refractive index different from the first refractive index.

[0023] 1 is a chip layout diagram showing an example of a configuration of a photodetector according to the first embodiment. FIG. 2 is a block diagram showing an example of a configuration of a photodetector according to the first embodiment. FIG. 3 is an example of a circuit diagram of a pixel according to the first embodiment. FIG. 4 is a cross-sectional view showing the structure of a photodetector according to the first embodiment. FIG. 5 is a plan view of one pixel as seen from the second surface side. FIG. 6 is a plan view showing an example of a color arrangement of pixels in the first embodiment. FIG. 7 is a plan view showing another example of a color arrangement of pixels in the first embodiment. FIG. 8 is a cross-sectional view showing the structure of a photodetector according to a comparative example. FIG. 9 is a diagram showing changes in sensitivity of two photoelectric conversion elements with respect to the angle of incidence of light. FIG. 10 is a plan view showing an example of a color arrangement of pixels in the second embodiment. FIG. 11 is a plan view showing another example of a color arrangement of pixels in the second embodiment. FIG. 12 is a cross-sectional view showing the structure of a photodetector according to the second embodiment. FIG. 13 is a cross-sectional view showing the structure of a photodetector according to a third embodiment. FIG. 14 is a plan view showing an example of a color arrangement of pixels in the third embodiment. FIG. 15 is a cross-sectional view showing the structure of a photodetector according to a fourth embodiment. FIG. 16 is a cross-sectional view showing the structure of a photodetector according to a fifth embodiment. FIG. 17 is a cross-sectional view showing the structure of a photodetector according to a sixth embodiment. FIG. 18 is a cross-sectional view showing a part of the structure of a photodetector according to a seventh embodiment. FIG. 19 is a cross-sectional view showing the structure of another part of the photodetector according to the seventh embodiment. FIG. 20 is a diagram showing the sensitivity of a photoelectric conversion element to incident light of the color filter shown in FIG. 19 . FIG. 21 is a diagram showing the sensitivity of a photoelectric conversion element to incident light of the color filter shown in FIG. 20 . FIG. 22 is a cross-sectional view showing the structure of a photodetector according to an eighth embodiment. FIG. 23 is a cross-sectional view showing the structure of a photodetector according to a ninth embodiment. FIG. 24 is a cross-sectional view showing the structure of a photodetector according to a tenth embodiment. FIG. 25 is a cross-sectional view showing the structure of a photodetector according to an eleventh embodiment. FIG. 26 is a cross-sectional view showing the structure of a photodetector according to a twelfth embodiment. FIG. 27 is a cross-sectional view showing the structure of a photodetector according to a thirteenth embodiment. FIG. 28 is a cross-sectional view showing the structure of a photodetector according to a fourteenth embodiment. FIG. 29 is a cross-sectional view showing the structure of a photodetector according to a fifteenth embodiment. FIG. 29 is a cross-sectional view showing the structure of a photodetector according to a sixteenth embodiment. FIG. 29 is a cross-sectional view showing the structure of a photodetector according to an eighteenth embodiment. FIG. 30 is a block diagram showing an example configuration of an electronic device according to a nineteenth embodiment.It is a block diagram showing an example of a schematic configuration of a vehicle control system.It is an explanatory diagram showing an example of the installation positions of a vehicle outside information detection unit and an imaging unit.

[0024] First Embodiment Fig. 1 is a chip layout diagram showing an example of the configuration of a photodetector according to a first embodiment. As shown in Fig. 1, a photodetector 1 according to this embodiment is provided on a semiconductor chip 2. The semiconductor chip 2 has a pixel region 2A and a peripheral region 2B. The pixel region 2A is provided in the center of the semiconductor chip 2. On the other hand, the peripheral region 2B is provided on the outer periphery of the semiconductor chip 2 so as to surround the pixel region 2A.

[0025] The pixel region 2A is a light receiving region that receives incident light. The pixel region 2A is configured as a pixel array in which a plurality of pixels 3 are arranged in a matrix along the X direction (row direction) and the Y direction (column direction). In this embodiment, the X direction and the Y direction are orthogonal to each other. The direction orthogonal to both the X direction and the Y direction is the Z direction (thickness direction, stacking direction).

[0026] A plurality of bonding pads 14 are arranged in the peripheral region 2B. Each of the plurality of bonding pads 14 is arranged along each of the four sides of the rectangular pixel region 2A. Each of the plurality of bonding pads 14 is an input / output terminal used when electrically connecting the semiconductor chip 2 to an external device.

[0027] 2 is a block diagram showing an example of the configuration of the photodetector 1 according to the first embodiment. As shown in Fig. 2, the semiconductor chip 2 includes a logic circuit 13. The logic circuit 13 includes a vertical drive circuit 4, a column signal processing circuit 5, a horizontal drive circuit 6, an output circuit 7, and a control circuit 8. The logic circuit 13 is configured as a CMOS circuit having, for example, n-channel conductivity type MOS transistors and p-channel conductivity type MOS transistors as field effect transistors.

[0028] The vertical drive circuit 4 is configured, for example, by a shift register. The vertical drive circuit 4 sequentially selects a plurality of pixel drive lines 10 and supplies pulses to the selected pixel drive lines 10 to drive the pixels 3, thereby driving each pixel 3 row by row. Specifically, the vertical drive circuit 4 sequentially selects and scans each pixel 3 in the pixel region 2A row by row in the vertical direction. As a result, each pixel 3 generates a pixel signal based on a signal charge corresponding to the amount of light received. The generated pixel signal is input to the column signal processing circuit 5 via vertical signal lines 11.

[0029] A column signal processing circuit 5 is arranged for each column of pixels 3. The column signal processing circuit 5 performs signal processing such as noise removal for each pixel column on pixel signals output from one row of pixels 3. For example, the column signal processing circuit 5 performs signal processing such as CDS (Correlated Double Sampling) and AD (Analog-Digital) conversion to remove fixed pattern noise specific to the pixels. A horizontal selection switch (not shown) is provided at the output stage of the column signal processing circuit 5 and connected between the output stage and the horizontal signal line 12.

[0030] The horizontal drive circuit 6 is configured by, for example, a shift register. The horizontal drive circuit 6 sequentially outputs horizontal scanning pulses to the column signal processing circuits 5, thereby selecting each of the column signal processing circuits 5 in turn. As a result, pixel signals are output from each of the column signal processing circuits 5 to the horizontal signal line 12.

[0031] The output circuit 7 processes and outputs pixel signals sequentially input from each of the column signal processing circuits 5 via the horizontal signal line 12. This signal processing includes, for example, buffering, black level adjustment, column variation correction, various types of digital signal processing, and the like.

[0032] Based on the vertical synchronization signal, horizontal synchronization signal, and master clock signal, the control circuit 8 generates clock signals and control signals that serve as references for the operations of the vertical drive circuit 4, column signal processing circuit 5, horizontal drive circuit 6, etc. The control circuit 8 outputs the generated clock signals and control signals to the vertical drive circuit 4, column signal processing circuit 5, horizontal drive circuit 6, etc.

[0033] 3 is an example of a circuit diagram of a pixel 3 according to the first embodiment. As shown in FIG. 3 , the pixel 3 includes a photoelectric conversion unit 16. The photoelectric conversion unit 16 includes photoelectric conversion elements PD1 and PD2, charge accumulation regions (floating diffusions) FD1 and FD2 that accumulate (hold) signal charges photoelectrically converted by the photoelectric conversion elements PD1 and PD2, and transfer transistors TR1 and TR2 that transfer the signal charges photoelectrically converted by the photoelectric conversion elements PD1 and PD2 to the charge accumulation regions FD1 and FD2. The pixel 3 also includes a readout circuit 15 electrically connected to the photoelectric conversion unit 16, more specifically, to the charge accumulation regions FD1 and FD2.

[0034] The two photoelectric conversion elements PD1 and PD2 correspond to a first photoelectric conversion element and a second photoelectric conversion element, respectively, that generate signal charges according to the amount of received light. The photoelectric conversion elements PD1 and PD2 also temporarily accumulate (hold) the generated signal charges. The cathode side of the photoelectric conversion element PD1 is electrically connected to the source region of the transfer transistor TR1, and the anode side is electrically connected to a reference potential line (e.g., ground). The cathode side of the photoelectric conversion element PD2 is electrically connected to the source region of the transfer transistor TR2, and the anode side is electrically connected to a reference potential line (e.g., ground). The photoelectric conversion elements PD1 and PD2 are, for example, photodiodes.

[0035] Of the two transfer transistors TR1 and TR2, the drain region of the transfer transistor TR1 is electrically connected to the charge storage region FD1. The gate electrode of the transfer transistor TR1 is electrically connected to a transfer transistor drive line of the pixel drive lines 10 (see FIG. 2). The drain region of the transfer transistor TR2 is electrically connected to the charge storage region FD2. The gate electrode of the transfer transistor TR2 is electrically connected to a transfer transistor drive line of the pixel drive lines 10.

[0036] The charge storage region FD1 temporarily stores and holds the signal charge transferred from the photoelectric conversion element PD1 via the transfer transistor TR1, while the charge storage region FD2 temporarily stores and holds the signal charge transferred from the photoelectric conversion element PD2 via the transfer transistor TR2.

[0037] The readout circuit 15 reads out the signal charges accumulated in the charge accumulation regions FD1 and FD2 and outputs a pixel signal based on the signal charges. The readout circuit 15 includes pixel transistors, for example, an amplification transistor AMP, a selection transistor SEL, and a reset transistor RST. Note that the circuit configuration of the readout circuit 15 is not limited to the circuit diagram shown in FIG. 3.

[0038] The pixel transistors (AMP, SEL, RST) are configured as MOS transistors having a gate insulating film made of, for example, a silicon oxide film (SiO2 film), a gate electrode, and a pair of main electrode regions that function as a source region and a drain region. ３ N ４ Alternatively, a metal insulator semiconductor field effect transistor (MISFET) made of a laminated film such as a silicon nitride film and a silicon oxide film may be used.

[0039] The amplifier transistor AMP has a source region electrically connected to the drain region of the select transistor SEL, a drain region electrically connected to the power supply line Vdd and the drain region of the reset transistor RST, and a gate electrode electrically connected to the charge storage regions FD1 and FD2 and the source region of the reset transistor RST.

[0040] The selection transistor SEL has a source region electrically connected to the vertical signal line 11 (VSL), a drain electrically connected to the source region of the amplification transistor AMP, and a gate electrode electrically connected to a selection transistor drive line among the pixel drive lines 10 (see FIG. 2).

[0041] The reset transistor RST has a source region electrically connected to the charge storage regions FD1 and FD2 and the gate electrode of the amplifier transistor AMP, and a drain region electrically connected to the power supply line Vdd and the drain region of the amplifier transistor AMP. The gate electrode of the reset transistor RST is electrically connected to a reset transistor drive line among the pixel drive lines 10 (see FIG. 2).

[0042] The photodetector 1 has an autofocus function based on the phase difference between the signal charges accumulated in the two photoelectric conversion elements PD1 and PD2. When the focus is not correct, a phase difference occurs between the signal charge amount Q1 of the photoelectric conversion element PD1 and the signal charge amount Q2 of the photoelectric conversion element PD2. The focus is adjusted by reducing this phase difference.

[0043] After the focus adjustment is completed, an image is generated based on the sum of the signal charge amounts Q1 and Q2, that is, the sum of the signal charge amounts Q3 (Q3=Q1+Q2). That is, the sum of the signal charge amounts Q1 and Q2 corresponds to the pixel signal.

[0044] 4 is a cross-sectional view showing the structure of the photodetector 1 according to the first embodiment. As shown in FIG. 5, the photodetector 1 (semiconductor chip 2) includes a semiconductor layer 20, a fixed charge film 31, an anti-reflection film 32, an insulating film 33, a color filter layer 40, and a lens layer 50. A wiring layer (not shown) is stacked on a first surface S1, which is the bottom surface of the semiconductor layer 20. This wiring layer has a multilayer wiring structure. The multilayer wiring structure includes a plurality of wirings stacked via an insulating film and extending along the X and Y directions (horizontal directions), and a wiring extending along the Z direction (thickness direction) within the insulating film.

[0045] The semiconductor layer 20 is made of a semiconductor substrate such as single crystal silicon (Si). In a portion of the semiconductor layer 20 corresponding to the pixel region 2A, a plurality of cell regions 20a are provided in a matrix on a two-dimensional plane including the X direction and the Y direction. The cell region 20a is provided for each pixel 3. For example, an island-shaped cell region 20a partitioned by an isolation region 20b is provided for each pixel 3. Two pixels 3 are shown in FIG. 4.

[0046] The separation region 20b is provided with partition walls 21 having a trench structure. The partition walls 21 extend from the first surface S1 to the second surface S2 along the Z direction. The partition walls 21 can be formed by forming grooves along the Z direction in the separation region 20b of the semiconductor layer 20 and filling the formed grooves with a partition material. This partition material can be, for example, silicon oxide (SiO ２ ), air gap (air wall), polysilicon, metal material, high refractive index material, etc. can be used. High refractive index material includes, for example, titanium oxide (TiO ２ ), silicon nitride (Si ３ N ４ ), hafnium oxide (HfO ２ ), and tantalum oxide (Ta ２ O ５ ) can be used. Examples of the metal material that can be used include aluminum (Al), copper (Cu), titanium (Ti), and titanium nitride (TiN).

[0047] Fig. 5 is a plan view of one pixel 3 as viewed from the second surface S2 side. As shown in Fig. 5, the partition wall 21 surrounds the cell region 20a in plan view. A cross-sectional view of the pixel 3 taken along the cutting line A-A shown in Fig. 5 is shown in Fig. 4.

[0048] Two photoelectric conversion elements, a photoelectric conversion element PD1 (first photoelectric conversion element) and a photoelectric conversion element PD2 (second photoelectric conversion element), are configured in each cell region 20a. In the cell region 20a, the photoelectric conversion elements PD1 and PD2 are arranged side by side along the X direction. Furthermore, transfer transistors TR1 and TR2 and charge accumulation regions FD1 and FD2 may be formed in the cell region 20a.

[0049] Within the cell region 20a, a central isolation region 22 is provided between the semiconductor region 23 in which the photoelectric conversion element PD1 is arranged and the semiconductor region 24 in which the photoelectric conversion element PD2 is arranged. As shown in FIGS. 4 and 5 , the central isolation region 22 extends along the Z direction and the Y direction. The central isolation region 22 electrically isolates the photoelectric conversion element PD1 from the photoelectric conversion element PD2. The central isolation region 22 can be formed by ion implantation of impurities. The conductivity type of the central isolation region 22 is different from the conductivity types of the semiconductor regions 23 and 24.

[0050] A fixed charge film 31 is provided on the second surface S2 of the semiconductor layer 20 configured as described above. The fixed charge film 31 is provided so as to cover the partition walls 21 and the semiconductor regions 23 and 24. The fixed charge film 31 is a film having, for example, a negative fixed charge, and suppresses the generation of dark current at the interface of the semiconductor layer 20. The fixed charge film 31 is made of a metal oxide. The fixed charge film 31 contains at least one oxide of, for example, hafnium (Hf), zirconium (Zr), aluminum (Al), titanium (Ti), tantalum (Ta), magnesium (Mg), yttrium (Y), lanthanoid (La), or the like.

[0051] The fixed charge film 31 may also be composed of a metal nitride film or a metal oxynitride film, such as an aluminum nitride film, a hafnium oxynitride film, an aluminum oxynitride film, etc. Furthermore, a film having a positive fixed charge may be provided as the fixed charge film 31.

[0052] An anti-reflection film 32 is provided on the fixed charge film 31. The anti-reflection film 32 reduces (suppresses) reflection of incident light that has passed through the lens layer 50 and the color filter layer 40. The anti-reflection film 32 is made of a metal oxide, such as tantalum oxide or hafnium oxide. The anti-reflection film 32 may also be made of another metal oxide film, or may be made of a metal nitride film or a metal oxynitride film. The anti-reflection film 32 may also be made of an insulating material, such as a silicon oxide film or a silicon nitride film, or may be made of other materials.

[0053] An insulating film 33 is provided on the anti-reflection film 32. The insulating film 33 is formed of, for example, a single layer film made of one of an oxide film (e.g., a silicon oxide film), a nitride film (e.g., a silicon nitride film), and an oxynitride film, or a stacked film made of two or more of these. The insulating film 33 can also be called a planarizing film. A color filter layer 40 is provided on the insulating film 33.

[0054] 4, the color filter layer 40 includes color filters 41 and partition walls 42 that separate the color filters 41. Furthermore, the color filters 41 include a first portion 41a and a second portion 41b.

[0055] The thickness (height in the Z direction) of each of the first portion 41 a and the second portion 41 b is, for example, 200 nm or more. In this case, the thickness of the color filter 41 is 400 nm or more. Furthermore, for example, when the wavelength of light transmitted through the color filter 41 is 530 nm, that is, when the color filter 41 transmits green light, the light transmittance of each of the first portion 41 a and the second portion 41 b is 50% or more.

[0056] Furthermore, in this embodiment, the refractive index differs between the first portion 41a and the second portion 41b. The difference in refractive index between the first portion 41a and the second portion 41b is, for example, greater than 1.1. In this embodiment, the second refractive index n2 of the second portion 41b is higher than the first refractive index n1 of the first portion 41a. In addition, in this embodiment, the second portion 41b is a hemisphere disposed below the first portion 41a. Furthermore, the material of the second portion 41b may be the same as or different from the material of the first portion 41a.

[0057] If the materials of each portion are the same, for example, pigment or dye, the concentration of the pigment or dye contained in the second portion 41b is higher than the concentration of the pigment or dye contained in the first portion 41a. If the materials of each portion are different, the second portion 41b contains a material with a higher refractive index than the material of the first portion 41a. If the materials of each portion are different, the first portion 41a is made of a material having a first refractive index n1, and the second portion 41b is made of a material having a second refractive index n2.

[0058] The partition walls 42 are provided to further facilitate focusing of incident light onto the pixels 3. The partition walls 42 are made of a material having a lower refractive index than the material of the first portion 41a of the color filter 41. This allows the partition walls 42 to guide light, making it possible to further facilitate focusing of light that has passed through the lens layer 50 onto the pixels 3. The partition walls 42 can be made of a material such as silicon oxide (SiO ２ ), air, and a low refractive index material can be used. Examples of the low refractive index material include filler-filled silica and known low refractive index resin materials. Furthermore, since a difference in refractive index produces a waveguiding effect, the height of the partition wall 42 may be smaller than the thickness of the color filter 41.

[0059] Fig. 6 is a plan view showing an example of a color arrangement of pixels in the first embodiment. In Fig. 6, each pixel 3 is arranged to receive incident light through one of a red light filter R that transmits red light, a green light filter G that transmits green light, or a blue light filter B that transmits blue light.

[0060] In FIG. 6 , the light-receiving color of each pixel 3 is set based on a Quad Bayer array. In this Quad Bayer array, color filters of the same color are arranged in pairs along the X-row direction. This Quad Bayer array also has a pixel row in which two pixels 3 set to receive red light and two pixels 3 set to receive green light are arranged along the X-row direction. This Quad Bayer array also has a pixel row in which two pixels 3 set to receive blue light and two pixels 3 set to receive green light are arranged along the X-row direction. However, the color arrangement of the pixels 3 is not limited to the Quad Bayer array shown in FIG. 6 .

[0061] 7 is a plan view showing another example of a color array of pixels in the first embodiment. In FIG. 7, color filters 41 for each color light are arranged based on a Bayer array. This Bayer array has pixel rows in which pixels 3 set to receive green light and pixels 3 set to receive red light are alternately arranged along the X direction. This Bayer array also has pixel rows in which pixels 3 set to receive blue light and pixels 3 set to receive green light are alternately arranged along the X direction.

[0062] Light is incident on the color filters 41 of each color described above via on-chip lenses (microlenses) 51. The on-chip lenses 51 are provided on the lens layer 50 as shown in FIG. 4. The lens layer 50 is disposed on the color filter layer 40. In this embodiment, one on-chip lens 51 is provided for one pixel 3 as shown in FIGS. 4, 6, and 7. The material of the on-chip lenses 51 is, for example, a transparent resin. The refractive index of this transparent resin is, for example, approximately 1.5 or more and 1.6 or less.

[0063] Here, the structure of a photodetector that is a comparison target to the photodetector 1 according to this embodiment will be described.

[0064] 8 is a cross-sectional view showing the structure of a photodetector according to a comparative example, in which the same components as those in the photodetector 1 according to the first embodiment are denoted by the same reference numerals, and redundant description will be omitted.

[0065] The photodetector according to this comparative example is a dual PD type photodetector, similar to the photodetector 1 according to the first embodiment. In the dual PD type, two photoelectric conversion elements PD1 and PD2 are provided in a pair on the left and right sides within one pixel. The pair of photoelectric conversion elements PD1 and PD2 share one on-chip lens 51.

[0066] The photoelectric conversion elements PD1 and PD2 each generate a signal charge according to the amount of incident light. The autofocus function can be realized by determining the phase difference between the output of the photoelectric conversion element PD1 and the output of the photoelectric conversion element PD2. The separation ratio is one index that represents the autofocus performance that utilizes the phase difference between the two photoelectric conversion elements.

[0067] 9 is a diagram showing changes in the sensitivity of two photoelectric conversion elements with respect to the angle of incidence of light. In FIG. 9, the horizontal axis represents the angle of incidence of light incident on the on-chip lens 51. The vertical axis represents the sensitivity of the photoelectric conversion elements PD1 and PD2 to the incident light. This sensitivity is, for example, the ratio of the amount of light received by the photoelectric conversion elements PD1 and PD2 to the amount of incident light.

[0068] The separation ratio is the sensitivity difference S between the sensitivity of the photoelectric conversion element PD1 and the sensitivity of the photoelectric conversion element PD2. However, the separation ratio may also be the ratio obtained by dividing one sensitivity by the other sensitivity. In FIG. 9, the larger this sensitivity difference S, the higher the separation ratio. In other words, the larger the sensitivity difference S, the higher the autofocus performance.

[0069] In recent years, pixel miniaturization has been progressing in CMOS image sensors. Therefore, in the photodetector device according to the comparative example, the effect of light diffraction by the on-chip lens 51 may be insufficient when focusing incident light within the pixel 300. For example, as shown in FIG. 8 , when light L enters the pixel 300 from the upper right to the lower left of the page, it becomes difficult to sufficiently reduce the size of the focused spot. In this case, a portion of the light L intended to be received by the semiconductor region 23 in which the photoelectric conversion element PD1 is disposed leaks into the semiconductor region 24, which is not intended to be received. As a result, as shown in FIG. 9 , the sensitivity of the photoelectric conversion elements PD1 and PD2 changes from the state indicated by the dotted line to the state indicated by the solid line, and the sensitivity difference S decreases.

[0070] In contrast, in the photodetector 1 according to this embodiment, as shown in Fig. 4, each color filter 41 is provided with a first portion 41a and a second portion 41b having different refractive indices. The second portion 41b, which has a higher refractive index, functions as a convex lens. This enhances the concentration of incident light, making it less likely for the incident light to leak into semiconductor regions that are not intended for light detection.

[0071] Therefore, according to the photodetector 1 of this embodiment, the color filter 41 can adjust the color light receiving range even if the pixel 3 is miniaturized, which makes it possible to improve the autofocus function, which is one of the optical characteristics related to the reception of color light.

[0072] Hereinafter, several other embodiments of the present disclosure will be described. In the following description, the same components as those in the photodetector 1 according to the first embodiment described above will be denoted by the same reference numerals, and redundant description will be omitted.

[0073] Second Embodiment Fig. 10 is a plan view showing an example of a color array of pixels in a second embodiment. Fig. 10 shows an array in which a color filter 41 and an on-chip lens 51 are shared by two pixels 3. With this array, an autofocus function can be realized by calculating the phase difference between the two shared pixels 3.

[0074] This array has four types of pixel rows in which the light-receiving colors of the pixels 3 are different. In a first pixel row of the four types of pixel rows, four pixels 3 set to receive green light and two pixels 3 set to receive red light are alternately arranged along the X direction. In a second pixel row, two pixels 3 set to receive green light and four pixels 3 set to receive red light are alternately arranged along the X direction. In a third pixel row, four pixels 3 set to receive green light and two pixels 3 set to receive blue light are alternately arranged along the X direction. In a fourth pixel row, two pixels 3 set to receive green light and four pixels 3 set to receive blue light are alternately arranged along the X direction.

[0075] 10 , one on-chip lens 51 is provided for two pixels 3 that are adjacent in the X direction and have the same light-receiving color. Therefore, light that has passed through the on-chip lens 51 is incident on the color filters 41 of the same color for two pixels. Note that the relationship between the color array of the pixels 3 and the on-chip lenses 51 in the second embodiment is not limited to the example shown in FIG.

[0076] FIG. 11 is a plan view showing another example of a color array of pixels in the second embodiment. FIG. 11 shows an array in which four pixels 3 share a color filter 41 and an on-chip lens 51. With this array, an autofocus function can be achieved by calculating the phase difference between the two shared pixels 3. In this array, the light-receiving colors of the pixels 3 are set based on the same array as in the first embodiment shown in FIG. 6. However, in this embodiment, one on-chip lens 51 is provided for four pixels 3 that are adjacent in the X and Y directions and have the same light-receiving color. Therefore, light incident on the on-chip lens 51 passes through the color filters 41 of the same color for four pixels. Note that the relationship between the color array of the pixels 3 and the on-chip lens 51 in the second embodiment is not limited to the examples shown in FIGS. 10 and 11 .

[0077] Fig. 12 is a plan view showing yet another example of a color array of pixels in the second embodiment. In Fig. 12, the light-receiving colors of the pixels 3 are set based on the Quad Bayer array similar to that of the first embodiment shown in Fig. 6, except for the central region of the pixel array. In the central region of the pixel array, two pixels 3 set to receive green light are adjacent to each other in the X direction.

[0078] 12 , in the region excluding the central region of the pixel array, one on-chip lens 51a is provided for one pixel 3. On the other hand, in the central region of the pixel array, one on-chip lens 51b is provided for two pixels 3. That is, in the example shown in FIG. 12 , two types of on-chip lenses 51a and 51b having different shapes are provided on the color filter 41.

[0079] Fig. 13 is a cross-sectional view showing the structure of a photodetector according to the second embodiment. Two pixels 3 shown in Fig. 13 have color filters 41 that transmit green light. When the pixels 3 have the color arrangement shown in Fig. 12, Fig. 13 shows a cross section of the central region of the pixel array.

[0080] In the semiconductor layer 20 of the second embodiment, the cell region 20a1 and the cell region 20a2 adjacent to each other with the partition wall 21 in between are not provided with the central isolation region 22 described in the first embodiment. Therefore, a photoelectric conversion element PD1 is arranged in the cell region 20a1, and a photoelectric conversion element PD2 is arranged in the cell region 20a2. That is, a photoelectric conversion element PD is provided for each pixel 3.

[0081] Furthermore, in the color filter layer 40 of the second embodiment, the partition wall 42 described in the first embodiment is not provided between two pixels 3 adjacent in the X direction. Therefore, the first portion 41 a and the second portion 41 b are formed continuously across two pixels 3 adjacent in the X direction. Note that, for example, when the pixels 3 have the color arrangement shown in FIG. 11 , the partition wall 42 does not need to be provided not only between two pixels 3 adjacent in the X direction, but also between two pixels 3 adjacent in the Y direction. In this case, the first portion 41 a and the second portion 41 b are formed continuously across four pixels 3 adjacent in the X direction and four pixels 3 adjacent in the Y direction.

[0082] In the photodetector according to the present embodiment described above, an autofocus function can be realized by determining the phase difference between the output of the photoelectric conversion element PD1 arranged in the cell region 20a1 and the output of the photoelectric conversion element PD2 arranged in the cell region 20a2. In this case, as in the first embodiment, the color filter 41 of each color is provided with a first portion 41a and a second portion 41b having different refractive indices, so that the optical path of the incident light can be controlled.

[0083] Therefore, according to this embodiment, even if the pixel 3 is miniaturized, the incident light is less likely to leak into the cell region that is not the light receiving target. This improves the separation ratio of the incident light, and makes it possible to improve the autofocus function.

[0084] 14 is a cross-sectional view showing the structure of a photodetector according to a third embodiment, which will be described in comparison with the second embodiment described above.

[0085] In the semiconductor layer 20 of this embodiment, as in the second embodiment, one photoelectric conversion element PD is provided for one pixel 3. That is, a photoelectric conversion element PD1 is arranged in the cell region 20a1, and a photoelectric conversion element PD2 is arranged in the cell region 20a2. Furthermore, the central isolation region 22 is not provided in either the cell region 20a1 or the cell region 20a2.

[0086] Also in the color filter layer 40 of this embodiment, as in the second embodiment, one color filter 41 is shared by two pixels 3 adjacent to each other in the X direction, so that the first portion 41 a and the second portion 41 b are formed continuously across the two pixels 3 adjacent to each other in the X direction.

[0087] On the other hand, in this embodiment, an on-chip lens 51 is provided for each pixel 3. In other words, an on-chip lens 51 is provided for each cell region.

[0088] Fig. 15 is a plan view showing an example of a color arrangement of pixels in the third embodiment. The color arrangement shown in Fig. 15 is the same as the color arrangement of the second embodiment shown in Fig. 12. However, in this embodiment, as described above, an on-chip lens 51 is provided for each pixel 3. Therefore, one type of on-chip lens 51 is disposed in each pixel 3. In other words, the shape of the on-chip lens 51 disposed in the central region of the pixel array is the same as the shape of the on-chip lens 51 disposed in regions other than the central region.

[0089] According to the present embodiment described above, as in the second embodiment, the color filters 41 of each color are provided with first portions 41a and second portions 41b having different refractive indices, thereby controlling the optical path of incident light. This reduces the likelihood of incident light leaking into cell regions that are not intended for light reception, improving the separation ratio of incident light. As a result, the autofocus function can be improved.

[0090] Furthermore, in this embodiment, the shape of the on-chip lens 51 is common to each pixel 3. Therefore, even if the color arrangement of the pixels 3 is set to the color arrangement shown in FIG. 15 , it is not necessary to separately manufacture a plurality of types of on-chip lenses. This makes it possible to save the effort of manufacturing the on-chip lenses. However, in this embodiment, the color arrangement of the pixels 3 is not limited to the color arrangement shown in FIG. 15 , and may be the color arrangement shown in FIG. 6 .

[0091] 16 is a cross-sectional view showing the structure of a photodetector according to a fourth embodiment. Here, differences from the first embodiment will be mainly described.

[0092] In the color filter 41 according to this embodiment, the second portion 41b is a box-shaped body. This box-shaped body includes a rectangular parallelepiped and a square. In addition, a recess is provided in the lower part of the first portion 41a so as to surround the second portion 41b.

[0093] Even if the second part 41b of the color filter 41 is formed in a box shape, the light that passes through the on-chip lens 51 is refracted in the second part 41b and is focused toward the semiconductor region 23 or the semiconductor region 24 that is the light receiving target, depending on the angle of incidence.

[0094] Therefore, according to this embodiment, the optical path of the incident light can be controlled by the color filter 41. As a result, the incident light is less likely to leak into semiconductor regions that are not the light-receiving target. This improves the separation ratio of the incident light, thereby enabling an improved autofocus function.

[0095] 17 is a cross-sectional view showing the structure of a photodetector according to a fifth embodiment. The following description focuses on differences from the second embodiment. In the fifth embodiment, the shape of the second portion 41b of the color filter 41 differs from that of the second embodiment.

[0096] 17, in the color filter 41 according to this embodiment, the second portion 41b is formed in a box shape. A recess is provided at the bottom of the first portion 41a, surrounding the second portion 41b. In this case, as in the second embodiment, incident light is refracted by the second portion 41b and focused toward the target cell region, either the cell region 20a1 or the cell region 20a2, depending on the angle of incidence.

[0097] Therefore, in this embodiment, the color filter 41 can control the optical path of the incident light, so that the incident light is less likely to leak into cell regions that are not intended for receiving light even when the pixel 3 is miniaturized. This improves the separation ratio of the incident light, making it possible to improve the autofocus function.

[0098] 18 is a cross-sectional view showing the structure of a photodetector according to a sixth embodiment. The following description focuses on differences from the third embodiment. In the sixth embodiment, the shape of the second portion 41b of the color filter 41 differs from that of the third embodiment.

[0099] 18, in the color filter 41 according to this embodiment, the second portion 41b is formed in a box shape. A recess is provided at the bottom of the first portion 41a, surrounding the second portion 41b. In this case, as in the third embodiment, incident light is refracted at the second portion 41b and focused toward the target cell region, either the cell region 20a1 or the cell region 20a2, depending on the angle of incidence.

[0100] Therefore, according to this embodiment, the color filter 41 can control the optical path of the incident light, so that the incident light is less likely to leak into cell regions that are not intended for light reception even when the pixel 3 is miniaturized. This improves the separation ratio of the incident light, making it possible to improve the autofocus function.

[0101] Furthermore, the shape of the on-chip lens 51 is the same for each pixel 3. Therefore, even if the color arrangement of the pixels 3 is set to the color arrangement shown in Fig. 15, it is not necessary to fabricate a plurality of different types of on-chip lenses. Therefore, it is possible to save the effort of manufacturing the on-chip lenses.

[0102] 19 is a cross-sectional view showing a structure of a part of a photodetector according to a seventh embodiment. Here, differences from the first embodiment will be mainly described. In the seventh embodiment, the shape of the color filter 41 is different from that of the first embodiment.

[0103] In the color filter 41 of the pixel 3a according to this embodiment, the second portion 41b of the box-shaped body is disposed on one side in the X direction (the left side in FIG. 19 ), and the first portion 41a of the box-shaped body is disposed on the opposite side in the X direction from the second portion 41b (the right side in FIG. 19 ). That is, the first portion 41a and the second portion 41b are disposed side by side in the X direction in a box-shaped body.

[0104] In the color filter 41 according to the present embodiment configured as described above, light that has passed through the on-chip lens 51 is attracted to the second portion 41 b, which has a high refractive index. The attracted light is then distributed to the semiconductor region 23 or the semiconductor region 24 depending on the angle of incidence on the on-chip lens 51.

[0105] FIG. 20 is a cross-sectional view showing the structure of another part of the photodetector according to the seventh embodiment.

[0106] 20, the first portion 41a is disposed on one side in the X direction (the left side), and the second portion 41b is disposed on the opposite side in the X direction (the right side) of the first portion 41a. That is, the color filter 41 of the pixel 3b has the first portion 41a and the second portion 41b disposed laterally opposite to the color filter 41 of the pixel 3a.

[0107] Fig. 21 is a diagram showing the sensitivity of the photoelectric conversion elements PD1 and PD2 to incident light on the color filter 41 shown in Fig. 19. Fig. 22 is a diagram showing the sensitivity of the photoelectric conversion elements PD1 and PD2 to incident light on the color filter 41 shown in Fig. 20.

[0108] 19, photoelectric conversion element PD1 is arranged in semiconductor region 23 on the left side, and photoelectric conversion element PD2 is arranged in semiconductor region 24 on the right side. In addition, in color filter 41, second portion 41b with a high refractive index is arranged on the left side (semiconductor region 23 side), and first portion 41a with a low refractive index is arranged on the right side (semiconductor region 24 side). Therefore, as shown in FIG. 21, in a range where the incident angle of light is smaller than 0°, the sensitivity of photoelectric conversion element PD1 is higher than the sensitivity of photoelectric conversion element PD2, and the difference in sensitivity (separation ratio) also becomes large.

[0109] 20, the second portion 41b with a high refractive index is disposed on the right side (semiconductor region 24 side), and the first portion 41a with a low refractive index is disposed on the left side (semiconductor region 23 side). Therefore, as shown in Fig. 22, in the range where the incident angle of light is greater than 0°, the sensitivity of the photoelectric conversion element PD2 is higher than the sensitivity of the photoelectric conversion element PD1, and the sensitivity difference (separation ratio) also becomes large.

[0110] Therefore, according to this embodiment, the optical characteristics shown in Figures 21 and 22 can be combined by combining the color filters 41 shown in Figures 19 and 20. This makes it possible to improve the separation ratio over the range from negative incident angles to positive incident angles, thereby improving the autofocus function.

[0111] 23 is a cross-sectional view showing the structure of a photodetector according to an eighth embodiment. Here, differences from the first embodiment will be mainly described.

[0112] In the semiconductor layer 20 according to this embodiment, the photoelectric conversion element PD1 is arranged in the cell region 20a1, and the photoelectric conversion element PD2 is arranged in the cell region 20a2.

[0113] Furthermore, in the color filter layer 40 according to this embodiment, the second portion 41b of the color filter 41 has a shape that utilizes a so-called metasurface. That is, the second portion 41b is composed of a plurality of columns having different widths w and arranged along the X direction. The height h of each column is smaller than the wavelength of light transmitted through the color filter 41. Furthermore, in this embodiment, in order to focus light L toward the central regions of each of the cell regions 20a1 and 20a2, the width W of the central column among the plurality of columns arranged in the X direction is the widest.

[0114] According to the color filter 41 of this embodiment configured as described above, the second portion 41b refracts light incident on the on-chip lens 51 toward the center of the cell region 20a1 or 20a2 that is the light-receiving target, depending on the angle of incidence. This makes it less likely that the incident light will leak into cell regions that are not the light-receiving target. As a result, the separation ratio of the incident light is improved, which makes it possible to improve the autofocus function.

[0115] 24 is a cross-sectional view showing the structure of a photodetector according to a ninth embodiment. The following description will focus on the differences from the eighth embodiment.

[0116] In this embodiment, as shown in Fig. 24, not only the second portion 41b but also the first portion 41a is configured with a plurality of pillars having different widths extending in the Z direction. The height of the pillars constituting the first portion 41a is the same as the height h of each pillar constituting the second portion 41b. In other words, the pillars constituting the first portion 41a and the pillars constituting the second portion 41b are arranged alternately along the X direction.

[0117] In this embodiment as well, the height h of each column is smaller than the wavelength of light transmitted through the color filter 41. Therefore, in the color filter 41 according to this embodiment as well, the second portion 41b can refract light incident on the on-chip lens 51 toward the central region of the cell region 20a1 or the cell region 20a2 depending on the angle of incidence. This makes it less likely that incident light will leak into cell regions that are not intended for light reception, improving the separation ratio of the incident light and, as a result, enabling an improved autofocus function.

[0118] 25 is a cross-sectional view showing the structure of a photodetector according to a tenth embodiment. The following description focuses on the differences from the first embodiment. In this embodiment, photoelectric conversion element PD1 is disposed in cell region 20a1, and photoelectric conversion element PD2 is disposed in cell region 20a2.

[0119] In this embodiment, the second portion 41b is a rod-shaped body extending along the Z direction through the center of the color filter 41, and the first portion 41a is an annular body surrounding the second portion 41b. That is, the color filter 41 according to this embodiment has a core configuration similar to that of an optical fiber. This allows the second portion 41b to function as an optical waveguide, so that light incident on the on-chip lens 51 can be more strongly focused toward the central regions of the cell regions 20a1 and 20a2.

[0120] Therefore, according to this embodiment, the color filter 41 prevents incident light from leaking into cell regions that are not intended for light reception. This improves the separation ratio of incident light, thereby improving the autofocus function. Furthermore, the second portion 41b guides incident light to the cell regions corresponding to each color, thereby improving color mixing of light.

[0121] 26 is a cross-sectional view showing the structure of a photodetector according to an eleventh embodiment. The following description will focus on the differences from the first embodiment.

[0122] In the semiconductor layer 20 according to this embodiment, the photoelectric conversion element PD1 is arranged in the cell region 20a1, and the photoelectric conversion element PD2 is arranged in the cell region 20a2.

[0123] In the color filter layer 40 according to this embodiment, one color filter 41 is provided for each of the two cell regions 20a1 and 20a2. That is, no partition wall 42 is provided between the color filters 41 of the same color. In the color filter 41, the first portion 41a is formed as a convex body that protrudes downward (toward the cell region). Furthermore, the second portion 41b is formed as a concave body corresponding to the first portion 41a.

[0124] If the color filter 41 were composed of only the first portion 41a, the light L incident on the on-chip lens 51 might travel toward the boundary between the cell region 20a1 and the cell region 20a2 as shown by the dotted line in Fig. 31. In this case, there is a possibility that the light L will not reach the cell region to be received.

[0125] In contrast, in the color filter 41 according to this embodiment, a second portion 41b is provided below the first portion 41a. By adjusting the refractive index of the second portion 41b, it is possible to control the optical path so that the light L travels to the cell region to be received.

[0126] Therefore, according to this embodiment, the color filter 41 makes it difficult for incident light to leak into cell regions that are not intended for light reception, even when the pixels 3 are miniaturized. As a result, the second portion 41b guides the incident light to the cell regions corresponding to each color, thereby improving the color mixing of light, ensuring the separation ratio of the incident light, and providing an autofocus function.

[0127] 27 is a cross-sectional view showing the structure of a photodetector according to a twelfth embodiment. The following description focuses on differences from the second embodiment. The twelfth embodiment differs from the second embodiment in the shape of the second portion 41b of the color filter 41.

[0128] In the color filter 41 according to this embodiment, the second portion 41b is formed as a diffraction grating, as shown in Fig. 27. In this case, when incident light is diffracted by the second portion 41b, part of the incident light is directed toward the cell region 20a1 or 20a2 that is the light-receiving target, depending on the angle of incidence.

[0129] Therefore, according to this embodiment, the color filter 41 can control the optical path of incident light, so that even when the pixels 3 are miniaturized, the incident light is less likely to leak into cell regions that are not intended to receive light. This improves the separation ratio of the incident light, making it possible to improve the autofocus function. Furthermore, because the color filter 41 guides the incident light to the cell regions corresponding to each color, it is possible to prevent color mixing while maintaining the separation ratio of the incident light, or more precisely, to suppress the occurrence of sensitivity differences between the same colors.

[0130] 28 is a cross-sectional view showing the structure of a photodetector according to a thirteenth embodiment. The following description focuses on differences from the third embodiment. The thirteenth embodiment differs from the third embodiment in the shape of the second portion 41b of the color filter 41.

[0131] In the color filter 41 according to this embodiment, the second portion 41b is formed as a diffraction grating, as shown in Fig. 28. In this case, when incident light is diffracted by the second portion 41b, part of the incident light is directed toward the cell region 20a1 or 20a2 that is the light-receiving target, depending on the angle of incidence.

[0132] Therefore, according to this embodiment, the color filter 41 can control the optical path of incident light, so that even when the pixels 3 are miniaturized, incident light is less likely to leak into cell regions that are not intended for light reception. This improves the separation ratio of incident light, making it possible to improve the autofocus function. Furthermore, because the color filter 41 guides incident light to the cell regions corresponding to each color, it is possible to prevent color mixing while maintaining the separation ratio of incident light, or more precisely, to suppress the occurrence of sensitivity differences between the same colors.

[0133] Furthermore, in this embodiment, the shape of the on-chip lens is common to each pixel 3. Therefore, even if the color arrangement of the pixels 3 is set to the color arrangement shown in Fig. 15, it is not necessary to fabricate a plurality of different types of on-chip lenses. Therefore, it is possible to save the effort of manufacturing the on-chip lenses.

[0134] 29 is a cross-sectional view showing the structure of a photodetector according to a fourteenth embodiment. The following description focuses on differences from the second embodiment. The fourteenth embodiment differs from the second embodiment in the shape of the second portion 41 b of the color filter 41.

[0135] In the color filter 41 according to this embodiment, the second portion 41b is formed as a convex block, as shown in Fig. 29. In this case, incident light is refracted by the first portion 41a and the second portion 41b, and is directed toward the cell region 20a1 or the cell region 20a2 depending on the angle of incidence.

[0136] Therefore, according to this embodiment, the color filter 41 can control the optical path of incident light, so that even when the pixels 3 are miniaturized, the incident light is less likely to leak into cell regions that are not intended to receive light. This improves the separation ratio of the incident light, making it possible to improve the autofocus function. Furthermore, because the color filter 41 guides the incident light to the cell regions corresponding to each color, it is possible to prevent color mixing while maintaining the separation ratio of the incident light, or more precisely, to suppress the occurrence of sensitivity differences between the same colors.

[0137] 30 is a cross-sectional view showing the structure of a photodetector according to a fifteenth embodiment. The following description focuses on differences from the third embodiment. The fifteenth embodiment differs from the third embodiment in the shape of the second portion 41b of the color filter 41.

[0138] In the color filter 41 according to this embodiment, the second portion 41b is formed as a convex block, as shown in Fig. 30. In this case, incident light is refracted by the first portion 41a and the second portion 41b, and is directed toward the cell region 20a1 or the cell region 20a2 depending on the angle of incidence.

[0139] Therefore, according to this embodiment, since the color filter 41 can control the optical path of incident light, even when the pixel 3 is miniaturized, incident light is less likely to leak into cell regions that are not intended for light reception. This improves the separation ratio of incident light, making it possible to improve the autofocus function. Furthermore, since the color filter 41 guides incident light to the cell regions corresponding to each color, it is possible to prevent color mixing while maintaining the separation ratio of incident light, or more precisely, to suppress the occurrence of sensitivity differences between the same colors.

[0140] Furthermore, in this embodiment, the shape of the on-chip lens is common to each pixel 3. Therefore, even if the color arrangement of the pixels 3 is set to the color arrangement shown in Fig. 15, it is not necessary to fabricate a plurality of different types of on-chip lenses. Therefore, it is possible to save the effort of manufacturing the on-chip lenses.

[0141] 31 is a cross-sectional view showing the structure of a photodetector according to a sixteenth embodiment. The following description will focus on the differences from the eleventh embodiment.

[0142] In the lens layer 50 according to this embodiment, one on-chip lens 51 is provided for two cell regions (pixels) of the same color that are adjacent in the X direction. Therefore, light that has passed through the on-chip lens 51 is incident on one color filter 41 that is provided directly below the on-chip lens 51.

[0143] In the color filter 41, as in the eighteenth embodiment, a second portion 41b formed in a concave body is disposed below a first portion 41a formed in a convex body. By adjusting the refractive index of this second portion 41b, it is possible to control the optical path of light incident on the color filter 41 so that it proceeds to the cell region to be detected.

[0144] Therefore, according to this embodiment, even if the pixel 3 is miniaturized, incident light is less likely to leak into cell regions that are not intended for light reception. This improves the separation ratio of incident light, making it possible to improve the autofocus function. Furthermore, because the second portion 41b guides incident light to the cell regions corresponding to each color, it is possible to improve the separation ratio of incident light while improving light mixing, thereby ensuring the autofocus function.

[0145] 32 is a cross-sectional view showing the structure of a photodetector according to a seventeenth embodiment. The following description will focus on the differences from the first embodiment described above.

[0146] In the semiconductor layer 20 according to this embodiment, the photoelectric conversion element PD1 is arranged in the cell region 20a1, and the photoelectric conversion element PD2 is arranged in the cell region 20a2.

[0147] In the color filter layer 40 according to this embodiment, the color filter 41 has a so-called Fabry-Perot structure and is configured as a laminate in which a first portion 41 a and a second portion 41 b are stacked in the Z direction. Specifically, the first portion 41 a is stacked between two second portions 41 b that face each other in the Z direction.

[0148] In the color filter 41 configured as described above, light incident on the on-chip lens 51 is repeatedly refracted at the first portion 41 a and the second portion 41 b, resulting in multiple reflections. This improves the light absorption characteristics of the color filter 41. In addition, by transmitting or reflecting light of a specific wavelength, it is possible to narrow the wavelength band of light to be transmitted or reflected. This makes it possible to prevent color mixing of colored light received in the cell region.

[0149] 18th Embodiment Fig. 33 is a cross-sectional view showing the structure of a photodetector according to the 18th embodiment. Here, differences from the above-described 17th embodiment will be mainly described. In this embodiment, the layered structure of the color filter 41 differs from that of the 17th embodiment. In the color filter 41 according to this embodiment, as shown in Fig. 33, a third portion 41c and a fourth portion 41d are layered between a first portion 41a and a second portion 41b.

[0150] The third portion 41c is disposed between the first portion 41a and the fourth portion 41d. The refractive index of the third portion 41c is higher than that of the first portion 41a and lower than that of the second portion 41b. The fourth portion 41d is disposed between the third portion 41c and the second portion 41b. The refractive index of the fourth portion 41d is higher than that of the third portion 41c and lower than that of the second portion 41b.

[0151] The color filter 41 configured as described above also has a so-called Fabry-Perot structure. Therefore, light incident on the on-chip lens 51 is repeatedly refracted not only by the first portion 41a and the second portion 41b but also by the third portion 41c and the fourth portion 41d. This improves the light absorption characteristics of the color filter 41. In addition, by transmitting or reflecting light of a specific wavelength, it is possible to narrow the wavelength band of light to be transmitted or reflected. This makes it possible to prevent color mixing of colored light received in the cell region.

[0152] The color filter 41 according to this embodiment has a four-layer structure in which the refractive index increases from the top layer to the bottom layer. However, the number of layers in the color filter 41 is not limited to four, and may be three or five or more. That is, the color filter 41 may be a laminate in which at least one portion having a third refractive index higher than the refractive index of the first portion 41a and lower than the refractive index of the second portion 41b is stacked between the first portion 41a and the second portion 41b.

[0153] Nineteenth Embodiment FIG. 34 is a block diagram showing an example of the configuration of an electronic device according to a nineteenth embodiment.

[0154] 34 is a video camera, a digital still camera, or the like. The electronic device 1000 includes a lens group 1001, a solid-state image sensor 1002, a DSP circuit 1003, a frame memory 1004, a display unit 1005, a recording unit 1006, an operation unit 1007, and a power supply unit 1008. The DSP circuit 1003, the frame memory 1004, the display unit 1005, the recording unit 1006, the operation unit 1007, and the power supply unit 1008 are connected to one another via a bus line 1009.

[0155] The lens group 1001 takes in incident light (image light) from a subject and forms an image on the imaging surface of the solid-state imaging device 1002 .

[0156] The solid-state imaging device 1002 is any one of the photodetector devices according to the above-described embodiments. The solid-state imaging device 1002 converts the amount of incident light that is imaged on the imaging surface by the lens group 1001 into an electrical signal on a pixel-by-pixel basis and supplies the pixel signal to the DSP circuit 1003.

[0157] The DSP circuit 1003 performs predetermined image processing on the pixel signals supplied from the solid-state image sensor 1002, and supplies the processed image signals to a frame memory 1004 on a frame-by-frame basis for temporary storage.

[0158] The display unit 1005 is formed of a panel display device such as a liquid crystal panel or an organic EL (Electro Luminescence) panel, and displays an image based on pixel signals in frame units that are temporarily stored in the frame memory 1004 .

[0159] The recording unit 1006 is made up of a DVD (Digital Versatile Disk), a flash memory, or the like, and reads out and records the pixel signals in units of frames that are temporarily stored in the frame memory 1004 .

[0160] An operation unit 1007, under user operation, issues operation commands for various functions of the electronic device 1000. A power supply unit 1008 supplies power to the DSP circuit 1003, frame memory 1004, display unit 1005, recording unit 1006, and operation unit 1007.

[0161] The electronic device to which this technology can be applied may be any device that uses a photodetector in the image capture section (photoelectric conversion section), and in addition to the electronic device 1000, includes a portable terminal device with an imaging function and a copier that uses a photodetector in the image reading section.

[0162] The electronic device 1000 according to the present embodiment described above is equipped with any one of the photodetector devices according to the above-described embodiments as the solid-state imaging element 1002. This improves the optical characteristics of the solid-state imaging element 1002, thereby enabling the performance of the electronic device 1000 to be improved.

[0163] <Application to a Mobile Body> 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 realized as a device mounted on any type of mobile body, such as an automobile, an electric vehicle, a hybrid electric vehicle, a motorcycle, a bicycle, personal mobility, an airplane, a drone, a ship, or a robot.

[0164] FIG. 35 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 according to the present disclosure can be applied.

[0165] The vehicle control system 12000 includes a plurality of electronic control units connected via a communication network 12001. In the example shown in Fig. 35, 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. Also shown as functional components of the integrated control unit 12050 are a microcomputer 12051, an audio / video output unit 12052, and an in-vehicle network I / F (interface) 12053.

[0166] The drivetrain control unit 12010 controls the operation of devices related to the drivetrain of the vehicle in accordance with various programs. For example, the drivetrain control unit 12010 functions as a control device for a drive force generating device for generating a drive force of 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 of the vehicle.

[0167] The body system control unit 12020 controls the operation of various devices equipped 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, backup lamps, brake lamps, turn signals, and fog lamps. In this case, radio waves transmitted from a portable device that serves as a key or signals from various switches can be input to the body system control unit 12020. The body system control unit 12020 receives these radio waves or signals and controls the vehicle's door lock device, power window device, lamps, etc.

[0168] The outside-vehicle information detection unit 12030 detects information outside the vehicle equipped with the vehicle control system 12000. For example, an imaging unit 12031 is connected to the outside-vehicle information detection unit 12030. The outside-vehicle information detection unit 12030 causes the imaging 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, characters on the road surface, etc. based on the received images.

[0169] The imaging unit 12031 is an optical sensor that receives light and outputs an electrical signal corresponding 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 invisible light such as infrared light.

[0170] 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 degree of fatigue or concentration of the driver based on the detection information input from the driver state detection unit 12041, or may determine whether the driver is dozing off.

[0171] The microcomputer 12051 can calculate control target values ​​for 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 control commands 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 vehicle collision avoidance or impact mitigation, following driving based on the inter-vehicle distance, vehicle speed maintenance driving, vehicle collision warning, vehicle lane departure warning, etc.

[0172] In addition, the microcomputer 12051 can perform cooperative control for the purpose of autonomous driving, which allows the vehicle to travel autonomously without relying on driver operation, by controlling the driving force generating device, steering mechanism, braking device, etc. based on information about the surroundings of the vehicle obtained by the outside vehicle information detection unit 12030 or the inside vehicle information detection unit 12040.

[0173] Furthermore, the microcomputer 12051 can output a control command to the body system control unit 12020 based on the information outside the vehicle acquired by the outside 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 information detection unit 12030, and perform cooperative control aimed at preventing glare, such as switching from high beams to low beams.

[0174] The audio / video output unit 12052 transmits at least one of audio and video output signals to an output device capable of visually or audibly notifying the passengers of the vehicle or the outside of the vehicle of information. In the example of Fig. 37, the output devices are exemplified by an audio speaker 12061, a display unit 12062, and an instrument panel 12063. The display unit 12062 may include, for example, at least one of an on-board display and a head-up display.

[0175] FIG. 36 is a diagram showing an example of the installation position of the imaging unit 12031.

[0176] In FIG. 36 , a vehicle 12100 has imaging units 12101, 12102, 12103, 12104, and 12105 as the imaging unit 12031.

[0177] The imaging units 12101, 12102, 12103, 12104, and 12105 are provided, for example, at positions such as the front nose, side mirrors, rear bumper, back door, and the top of the windshield inside the vehicle cabin of the vehicle 12100. The imaging unit 12101 provided on the front nose and the imaging unit 12105 provided on the top of the windshield inside the vehicle cabin mainly acquire images of the front of the vehicle 12100. The imaging units 12102 and 12103 provided on the side mirrors mainly acquire images of the sides of the vehicle 12100. The imaging unit 12104 provided on the rear bumper or back door mainly acquires images of the rear of the vehicle 12100. The forward images acquired by the imaging units 12101 and 12105 are mainly used to detect preceding vehicles, pedestrians, obstacles, traffic lights, traffic signs, lanes, etc.

[0178] 38 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, by overlaying the image data captured by the imaging units 12101 to 12104, an overhead image of the vehicle 12100 viewed from above can be obtained.

[0179] At least one of the image capturing units 12101 to 12104 may have a function of acquiring distance information. For example, at least one of the image capturing units 12101 to 12104 may be a stereo camera made up of multiple image capturing elements, or may be an image capturing element having pixels for phase difference detection.

[0180] For example, based on the distance information obtained from the imaging units 12101 to 12104, the microcomputer 12051 can calculate the distance to each three-dimensional object within the imaging ranges 12111 to 12114 and the change in this distance over time (relative speed with respect to the vehicle 12100), thereby extracting as a preceding vehicle, in particular, the three-dimensional object that is the closest three-dimensional object on the path of the vehicle 12100 and traveling in approximately the same direction as the vehicle 12100 at a predetermined speed (e.g., 0 km / h or higher). Furthermore, the microcomputer 12051 can set a vehicle-to-vehicle distance to be maintained in advance in front of the preceding vehicle, and perform automatic braking control (including follow-up stop control), automatic acceleration control (including follow-up start control), etc. In this way, cooperative control can be performed for the purpose of autonomous driving, which runs autonomously without relying on driver operation.

[0181] For example, the microcomputer 12051 classifies and extracts three-dimensional object data regarding three-dimensional objects into two-wheeled vehicles, ordinary vehicles, large vehicles, pedestrians, utility poles, and other three-dimensional objects based on distance information obtained from the imaging units 12101 to 12104, and can use the data for automatic obstacle avoidance. 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. 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 greater than a set value and a collision is possible, 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.

[0182] At least one of the image capturing 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 a pedestrian is present in the images captured by the image capturing units 12101 to 12104. Such pedestrian recognition is performed, for example, by extracting feature points from the images captured by the image capturing units 12101 to 12104 as infrared cameras and performing pattern matching on a series of feature points that indicate the outline of an object to determine whether the object is a pedestrian. When the microcomputer 12051 determines that a pedestrian is present in the images captured by the image capturing units 12101 to 12104 and recognizes the pedestrian, the audio / image output unit 12052 controls the display unit 12062 to superimpose a rectangular outline on the recognized pedestrian for emphasis. The audio / image output unit 12052 may also control the display unit 12062 to display an icon or the like indicating the pedestrian at a desired position.

[0183] An example of a vehicle 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, for example, the image capture unit 12031 among the above-described configurations. Specifically, the image capture unit 12031 can be equipped with any of the photodetector devices according to the above-described embodiments. By applying the technology according to the present disclosure to the image capture unit 12031, optical characteristics are improved. As a result, the performance of the vehicle 12100 can be improved.

[0184] Note that the above-described embodiments are examples for realizing the present technology, and the matters in the embodiments correspond to the matters specifying the invention in the claims. Similarly, the matters specifying the invention in the claims correspond to the matters in the embodiments of the present technology having the same names. However, the present technology is not limited to the embodiments, and can be realized by applying various modifications to the embodiments within the scope of the gist of the present technology.

[0185] The present technology can be configured as follows:

[0186] (1) A photodetector comprising: a lens onto which light is incident; a color filter that transmits specific colored light contained in the light that has passed through the lens; and a photoelectric conversion element that photoelectrically converts the specific colored light received through the color filter, wherein the color filter has a first portion having a first refractive index and a second portion having a second refractive index different from the first refractive index.

[0187] (2) The light detection device according to (1), wherein the photoelectric conversion element includes: a first photoelectric conversion element; and a second photoelectric conversion element arranged alongside the first photoelectric conversion element and performing photoelectric conversion on color light of the same color as that of the first photoelectric conversion element.

[0188] (3) The light detection device according to (1) or (2), wherein the second portion is a hemisphere.

[0189] (4) The light detection device according to (1) or (2), wherein the second portion is a box-shaped body.

[0190] (5) The photodetector according to (1) or (2), wherein the second portion is a diffraction grating.

[0191] (6) The light detection device according to (1) or (2), wherein the second portion is a convex block.

[0192] (7) The light detection device according to (1) or (2), wherein the first portion and the second portion are box-shaped bodies arranged side by side.

[0193] (8) The photodetector according to (1) or (2), wherein the second portion is composed of a plurality of pillars having different widths, and the height of each of the plurality of pillars is smaller than the wavelength of the color light.

[0194] (9) The photodetector according to (8), wherein the first portion is also composed of a plurality of pillars having different widths, and the pillars constituting the first portion and the pillars constituting the second portion are arranged alternately.

[0195] (10) The photodetector according to (1) or (2), wherein the second portion is a rod-shaped body provided at the center of the color filter, and the first portion is an annular body surrounding the first portion.

[0196] (11) The light detection device according to (1) or (2), wherein the second portion is a concave body.

[0197] (12) The photodetector according to (1) or (2), wherein the color filter is a laminate in which the first portion is laminated between two of the second portions.

[0198] (13) The photodetector according to (1) or (2), wherein the color filter is a laminate in which at least one portion having a third refractive index higher than the first refractive index and lower than the second refractive index is laminated between the first portion and the second portion.

[0199] (14) The photodetector according to (2), wherein one color filter is provided for each of the first photoelectric conversion element and the second photoelectric conversion element.

[0200] (15) The photodetector according to (1) or (2), wherein the material of the first portion is the same as the material of the second portion, and the material concentration of the first portion is different from the material concentration of the second portion.

[0201] (16) The photodetector according to (1) or (2), wherein the first portion is made of a material having the first refractive index, and the second portion is made of a material having the second refractive index.

[0202] (17) An electronic device comprising a photodetector having a lens onto which light is incident, a color filter that transmits specific colored light contained in the light that has passed through the lens, and a photoelectric conversion element that photoelectrically converts the specific colored light received through the color filter, wherein the color filter has a first portion having a first refractive index and a second portion having a second refractive index different from the first refractive index.

[0203] 1: Photodetector 41: Color filter 41a: First portion 41b: Second portion 51: On-chip lens PD1: First photoelectric conversion element PD2: Second photoelectric conversion element 1000: Electronic device

Claims

1. A light detection device comprising: a lens into which light is incident; a color filter that transmits a specific color of light contained in the light that passes through said lens; and a photoelectric conversion element that photoelectrically converts the specific color of light received through said color filter, wherein the color filter has a first portion having a first refractive index and a second portion having a second refractive index different from the first refractive index.

2. The light detection device according to claim 1, wherein the photoelectric conversion element includes: a first photoelectric conversion element; and a second photoelectric conversion element arranged alongside the first photoelectric conversion element and performing photoelectric conversion on color light of the same color as the first photoelectric conversion element.

3. The optical detection device of claim 1, wherein said second portion is a hemisphere.

4. The optical detection device of claim 1, wherein the second portion is a box-shaped body.

5. The optical detection device of claim 1, wherein said second portion is a diffraction grating.

6. The optical detection device of claim 1, wherein said second portion is a convex block.

7. The optical detection device of claim 1, wherein said first portion and said second portion are box-shaped bodies arranged side by side with each other.

8. The optical detection device of claim 1, wherein the second portion is composed of a plurality of pillars having different widths, and the height of each of the plurality of pillars is smaller than the wavelength of the color light.

9. The optical detection device of claim 8, wherein the first portion is also composed of a plurality of pillars having different widths, and the pillars constituting the first portion and the pillars constituting the second portion are arranged alternately.

10. The photodetection device according to claim 1, wherein the second portion is a rod-shaped body provided in the center of the color filter, and the first portion is an annular body surrounding the first portion.

11. The optical detection device of claim 1, wherein said second portion is a concave body.

12. The photodetection device of claim 1, wherein said color filter is a laminate in which said first portion is laminated between two of said second portions.

13. The optical detection device of claim 1, wherein the color filter is a laminate having at least one portion having a third refractive index higher than the first refractive index and lower than the second refractive index stacked between the first portion and the second portion.

14. The light detection device according to claim 2, wherein one of the color filters is provided for the first photoelectric conversion element and the second photoelectric conversion element.

15. The optical detection device of claim 1, wherein the material of said first portion is the same as the material of said second portion, and the concentration of material in said first portion is different from the concentration of material in said second portion.

16. The optical detection device of claim 1, wherein said first portion is comprised of a material having said first refractive index and said second portion is comprised of a material having said second refractive index.

17. An electronic device equipped with a photodetector having a lens into which light is incident, a color filter that transmits specific colored light contained in the light that passes through the lens, and a photoelectric conversion element that photoelectrically converts the specific colored light received through the color filter, wherein the color filter has a first portion having a first refractive index, and a second portion having a second refractive index different from the first refractive index.

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