Solid-state imaging device, manufacturing method of solid-state imaging device, and electronic device

Abstract

A solid-state imaging element (1) according to the present disclosure is provided with a semiconductor layer (20) and an isolation region (23). The semiconductor layer (20) comprises a plurality of photoelectric conversion parts which are arranged in a matrix form. The isolation region (23) isolates photoelectric conversion parts, which are adjacent to each other in the semiconductor layer (20), from each other. In addition, the isolation region (23) comprises a wall-like electrode (24) and a low absorption member (26). The wall-like electrode (24) is arranged in the form of a wall; and a negative bias voltage is applied thereto. The low absorption member (26) is arranged closer to the light incident side than the wall-like electrode (24), while having a lower optical absorptance than the wall-like electrode (24).

Description

[Technical Field]

[0001] The present disclosure relates to a solid-state imaging device, a method for manufacturing a solid-state imaging device, and an electronic device. [Background technology]

[0002] A solid-state imaging device has, for example, a plurality of photoelectric conversion units arranged along the light-incident surface of a semiconductor layer. In addition, a technique for forming a conductive light-shielding wall in an isolation region located between adjacent photoelectric conversion units in such a solid-state imaging device is known (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-88030 Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure proposes a solid-state imaging device capable of suppressing deterioration of the light-collection characteristics of a photoelectric conversion unit, a method for manufacturing the solid-state imaging device, and an electronic device. [Means for solving the problem]

[0005] According to the present disclosure, there is provided a solid-state imaging element. The solid-state imaging element includes a semiconductor layer and a separation region. The semiconductor layer has a plurality of photoelectric conversion units arranged in a matrix. The separation region separates adjacent photoelectric conversion units in the semiconductor layer. The separation region also includes a wall-shaped electrode and a low-absorption member. The wall-shaped electrode is arranged in a wall shape and a negative bias voltage is applied to the wall-shaped electrode. The low-absorption member is arranged closer to the light incident side than the wall-shaped electrode and has a lower light absorption rate than the wall-shaped electrode. [Brief explanation of the drawings]

[0006] [Figure 1]1 is a system configuration diagram illustrating a schematic configuration example of a solid-state imaging device according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a cross-sectional view schematically illustrating the structure of a pixel array unit according to an embodiment of the present disclosure. [Figure 3] 10A to 10C are diagrams for explaining a manufacturing process of a pixel array unit according to an embodiment of the present disclosure. [Figure 4] 10A to 10C are diagrams for explaining a manufacturing process of a pixel array unit according to an embodiment of the present disclosure. [Figure 5] 10A to 10C are diagrams for explaining a manufacturing process of a pixel array unit according to an embodiment of the present disclosure. [Figure 6] 10A to 10C are diagrams for explaining a manufacturing process of a pixel array unit according to an embodiment of the present disclosure. [Figure 7] 10A to 10C are diagrams for explaining a manufacturing process of a pixel array unit according to an embodiment of the present disclosure. [Figure 8] 10A to 10C are diagrams for explaining a manufacturing process of a pixel array unit according to an embodiment of the present disclosure. [Figure 9] FIG. 10 is a cross-sectional view schematically showing the structure of a pixel array section according to a first modified example of the embodiment of the present disclosure. [Figure 10] FIG. 10 is a diagram showing the relationship between the depth at which a low absorption member is disposed and the saturated charge amount of a light-receiving pixel in the first modified example of the embodiment of the present disclosure. [Figure 11] 10A to 10C are diagrams for explaining a manufacturing process of a pixel array unit according to Modification 1 of the embodiment of the present disclosure. [Figure 12] 10A to 10C are diagrams for explaining a manufacturing process of a pixel array unit according to Modification 1 of the embodiment of the present disclosure. [Figure 13] 10A to 10C are diagrams for explaining a manufacturing process of a pixel array unit according to Modification 1 of the embodiment of the present disclosure. [Figure 14] 10A to 10C are diagrams for explaining a manufacturing process of a pixel array unit according to Modification 1 of the embodiment of the present disclosure. [Figure 15] 10A to 10C are diagrams for explaining a manufacturing process of a pixel array unit according to Modification 1 of the embodiment of the present disclosure. [Figure 16]10A to 10C are diagrams for explaining a manufacturing process of a pixel array unit according to Modification 1 of the embodiment of the present disclosure. [Figure 17] 10A to 10C are diagrams for explaining a manufacturing process of a pixel array unit according to Modification 1 of the embodiment of the present disclosure. [Figure 18] FIG. 10 is a cross-sectional view schematically showing the structure of a pixel array section according to a second modification of the embodiment of the present disclosure. [Figure 19] FIG. 10 is a cross-sectional view schematically illustrating a structure of a pixel array section according to a third modification of the embodiment of the present disclosure. [Figure 20] FIG. 10 is a cross-sectional view schematically showing the structure of a pixel array section according to a fourth modification of the embodiment of the present disclosure. [Figure 21] FIG. 10 is a diagram showing a planar configuration of a pixel array unit according to a fifth modified example of the embodiment of the present disclosure. [Figure 22] FIG. 13 is a diagram showing a planar configuration of a pixel array unit according to a sixth modified example of the embodiment of the present disclosure. [Figure 23] FIG. 23 is a cross-sectional view taken along the line AA shown in FIG. 22. [Figure 24] FIG. 23 is a cross-sectional view taken along the line BB shown in FIG. 22. [Figure 25] 1 is a block diagram illustrating an example of the configuration of an imaging device as an electronic device to which the technology according to the present disclosure is applied. [Figure 26] 1 is a block diagram showing an example of a schematic configuration of a vehicle control system; [Figure 27] FIG. 2 is an explanatory diagram showing an example of the installation positions of an outside-vehicle information detection unit and an imaging unit. DETAILED DESCRIPTION OF THE INVENTION

[0007] Hereinafter, each embodiment of the present disclosure will be described in detail with reference to the drawings. In the following embodiments, the same components are designated by the same reference numerals, and redundant description will be omitted.

[0008] A solid-state imaging device has, for example, a plurality of photoelectric conversion units arranged along a light-incident surface of a semiconductor layer, and a technique for forming a conductive light-shielding wall in an isolation region located between adjacent photoelectric conversion units in such a solid-state imaging device is known.

[0009] Furthermore, by applying a negative bias voltage to such a light-shielding wall, holes can be collected near the interface between the photoelectric conversion section and the separation region, thereby suppressing the occurrence of dark current and white spots in the photoelectric conversion section.

[0010] On the other hand, in the above-described conventional technology, a considerable amount of light is absorbed at the light incident side of the light-shielding wall, which may reduce the amount of light incident on the photoelectric conversion section.

[0011] Therefore, it is desired to realize a technology that can overcome the above-mentioned problems and suppress the deterioration of the light-collecting characteristics of the photoelectric conversion section.

[0012] [Structure of solid-state imaging device] 1 is a system configuration diagram showing a schematic configuration example of a solid-state imaging device 1 according to an embodiment of the present disclosure. As shown in FIG. 1, the solid-state imaging device 1, which is a CMOS image sensor, includes a pixel array unit 10, a system control unit 12, a vertical drive unit 13, a column readout circuit unit 14, a column signal processing unit 15, a horizontal drive unit 16, and a signal processing unit 17.

[0013] The pixel array section 10, system control section 12, vertical drive section 13, column readout circuit section 14, column signal processing section 15, horizontal drive section 16 and signal processing section 17 are provided on the same semiconductor substrate or on multiple electrically connected stacked semiconductor substrates.

[0014] The pixel array section 10 has light-receiving pixels 11 arranged two-dimensionally in a matrix, each having a photoelectric conversion element (photodiode PD (see Figure 2)) that can photoelectrically convert an amount of charge corresponding to the amount of incident light, store it internally, and output it as a signal.

[0015] In addition to the light-receiving pixels 11, the pixel array section 10 may include an area in which dummy pixels having a structure that does not have a photodiode PD, light-shielding pixels that block light incident from outside by shading the light-receiving surface, etc. are arranged in rows and / or columns.

[0016] The light-shielding pixels may have the same configuration as the light-receiving pixels 11, except that the light-receiving surfaces are structured so as to be light-shielded. In the following description, the photocharges corresponding to the amount of incident light may also be simply referred to as "charges," and the light-receiving pixels 11 may also be simply referred to as "pixels."

[0017] In the pixel array unit 10, pixel drive lines LD are formed for each row along the left-right direction in the drawing (the direction in which pixels in a pixel row are arranged) for the matrix-like pixel arrangement, and vertical pixel wiring LV is formed for each column along the up-down direction in the drawing (the direction in which pixels in a pixel column are arranged). One end of the pixel drive line LD is connected to an output terminal of the vertical drive unit 13 corresponding to each row.

[0018] The column readout circuit unit 14 includes at least a circuit that supplies a constant current to the light-sensitive pixels 11 in a selected row in the pixel array unit 10 for each column, a current mirror circuit, and a switch for selecting the light-sensitive pixel 11 to be read out.

[0019] The column readout circuit unit 14 forms an amplifier together with the transistor in the selected pixel in the pixel array unit 10, converts the photocharge signal into a voltage signal, and outputs it to the vertical pixel line LV.

[0020] The vertical drive unit 13 includes a shift register, an address decoder, etc., and drives each of the light-receiving pixels 11 in the pixel array unit 10, either all pixels at the same time or row by row, etc. Although the specific configuration of this vertical drive unit 13 is not shown in the figure, it is configured to have a readout scanning system and a sweep scanning system or a batch sweep and batch transfer system.

[0021] The readout scanning system sequentially selects and scans the light-receiving pixels 11 of the pixel array unit 10 row by row to read out pixel signals from the light-receiving pixels 11. In the case of row driving (rolling shutter operation), for the readout row on which the readout scanning system is to perform readout scanning, the readout scanning is performed in advance of the readout scanning by the shutter speed.

[0022] In the case of global exposure (global shutter operation), a collective discharge is performed prior to the collective transfer by the time of the shutter speed. This discharge discharges (resets) unnecessary charges from the photodiodes PD of the light-receiving pixels 11 in the readout row. The discharge (reset) of unnecessary charges then performs a so-called electronic shutter operation.

[0023] Here, the electronic shutter operation refers to an operation of discarding unnecessary photocharges that have been accumulated in the photodiode PD until just before, and starting new exposure (starting accumulation of photocharges).

[0024] The signal read by the readout operation by the readout scanning system corresponds to the amount of light that has entered since the previous readout operation or electronic shutter operation. In the case of row driving, the period from the readout timing of the previous readout operation or the sweep timing of the electronic shutter operation to the readout timing of the current readout operation is the accumulation time (exposure time) of the photocharges in the light-sensitive pixels 11. In the case of global exposure, the time from the collective sweep to the collective transfer is the accumulation time (exposure time).

[0025] The pixel signals output from each of the light-receiving pixels 11 in a pixel row selected and scanned by the vertical drive unit 13 are supplied through each of the vertical pixel wirings LV to a column signal processing unit 15. The column signal processing unit 15 performs predetermined signal processing on the pixel signals output from each of the light-receiving pixels 11 in the selected row through the vertical pixel wirings LV for each pixel column in the pixel array unit 10, and temporarily stores the pixel signals after signal processing.

[0026] Specifically, the column signal processing unit 15 performs at least noise removal processing, such as CDS (Correlated Double Sampling) processing, as signal processing. The CDS processing by the column signal processing unit 15 removes pixel-specific fixed pattern noise such as reset noise and threshold variation of the amplification transistor AMP.

[0027] In addition to the noise removal processing, the column signal processing unit 15 may be configured to have, for example, an AD conversion function so as to output pixel signals as digital signals.

[0028] The horizontal driving unit 16 includes a shift register, an address decoder, etc., and sequentially selects unit circuits corresponding to pixel columns in the column signal processing unit 15. By selective scanning by this horizontal driving unit 16, pixel signals that have been signal-processed by the column signal processing unit 15 are output sequentially to the signal processing unit 17.

[0029] The system control unit 12 includes a timing generator that generates various timing signals, and controls the driving of the vertical driving unit 13, column signal processing unit 15, horizontal driving unit 16, etc. based on the various timing signals generated by the timing generator.

[0030] The solid-state imaging device 1 further includes a signal processing unit 17 and a data storage unit (not shown). The signal processing unit 17 has at least an addition processing function and performs various signal processing such as addition processing on the pixel signals output from the column signal processing unit 15.

[0031] The data storage unit temporarily stores data necessary for signal processing in the signal processing unit 17. The signal processing unit 17 and the data storage unit may be an external signal processing unit provided on a board separate from the solid-state imaging device 1, such as a DSP (Digital Signal Processor) or software processing, or may be mounted on the same board as the solid-state imaging device 1.

[0032] [Embodiment] Next, a detailed configuration of the pixel array section 10 according to the embodiment will be described with reference to Fig. 2. Fig. 2 is a cross-sectional view schematically showing the structure of the pixel array section 10 according to the embodiment of the present disclosure.

[0033] 2, the pixel array section 10 according to the embodiment includes a semiconductor layer 20, a wiring layer 30, and an optical layer 40. In the pixel array section 10, the optical layer 40, the semiconductor layer 20, and the wiring layer 30 are stacked in this order from the side where light L from the outside is incident (hereinafter also referred to as the light incident side).

[0034] In the semiconductor layer 20, a photodiode PD is formed by a first region 21 which is a semiconductor region of a first conductivity type (for example, N type) and a semiconductor region of a second conductivity type (for example, P type) (not shown) adjacent to the first region 21. The photodiode PD is an example of a photoelectric conversion unit.

[0035] Furthermore, a second region 22, which is a semiconductor region of a second conductivity type, is provided in a portion of the semiconductor layer 20 closer to the light incident side than the first region 21. That is, the second region 22, which has a lower impurity concentration than the first region 21, is provided in a portion of the semiconductor layer 20 closer to the light incident side than the first region 21.

[0036] Furthermore, in the semiconductor layer 20, isolation regions 23 are provided between adjacent photodiodes PD. The isolation regions 23 electrically and optically isolate the adjacent photodiodes PD. The isolation regions 23 are arranged, for example, in a grid pattern in the pixel array section 10 in a planar view.

[0037] The separation region 23 according to the embodiment includes a wall-shaped electrode 24, an insulating film 25, and a low-absorption member 26. The wall-shaped electrode 24 is made of a conductive material and is a wall-shaped electrode provided along the separation region 23 in a plan view. The wall-shaped electrode 24 is made of, for example, one selected from polysilicon, tungsten, and aluminum as a main component.

[0038] The wall-shaped electrode 24 is disposed in the semiconductor layer 20 from the surface 20b opposite to the light incident side (hereinafter also referred to as the opposite surface 20b) to a given depth X. The wall-shaped electrode 24 is also disposed adjacent to the first region 21. That is, the first region 21 is disposed in the semiconductor layer 20 from the opposite surface 20b to a given depth X.

[0039] An insulating film 25 is disposed between the wall-shaped electrode 24 and the first region 21. The insulating film 25 is made of an insulating material (for example, silicon oxide (SiO2) or the like).

[0040] Furthermore, wiring 32a located in the wiring layer 30 is connected to the wall-shaped electrode 24, and a negative bias voltage is applied via the wiring 32a. By applying a negative bias voltage to the wall-shaped electrode 24, holes can be collected near the interface between the photodiode PD and the isolation region 23. This makes it possible to suppress the generation of dark current and white spots in the photodiode PD in this embodiment.

[0041] On the other hand, since the wall-shaped electrode 24 has a relatively high absorption rate for light L, if it is positioned close to the light incident surface 20a (hereinafter also referred to as the light incident surface 20a) of the semiconductor layer 20, there is a risk that the wall-shaped electrode 24 will absorb light L in the vicinity of the light incident surface 20a.

[0042] 2, a low-absorption member 26 is disposed in a portion of the separation region 23 closer to the light incident side than the wall-shaped electrode 24. The low-absorption member 26 has, for example, approximately the same thickness as the wall-shaped portion formed by the wall-shaped electrode 24 and the insulating film 25.

[0043] The low absorption member 26 is made of a material that has a lower absorptivity for light L than the wall-shaped electrode 24 (for example, silicon oxide, hafnium oxide (HfO2), aluminum oxide (Al2O3), titanium oxide (TiO2), etc.).

[0044] This makes it possible to prevent the light L from being absorbed in the portion of the light incident side of the separation region 23. Therefore, according to the embodiment, it is possible to prevent deterioration of the light collection characteristics of the photodiode PD.

[0045] In addition, in the embodiment, the second region 22, which has a lower impurity concentration than the first region 21, may be disposed adjacent to the low absorption member 26. This makes it possible to suppress the generation of abnormal charges due to defects in the semiconductor layer 20, even near the interface between the low absorption member 26 and the second region 22, where no negative bias voltage is applied.

[0046] Therefore, according to the embodiment, it is possible to suppress the occurrence of white spots in the photodiode PD.

[0047] In the example of Figure 2, the second region 22 is shown as a semiconductor region of the second conductivity type, but the second region 22 is not limited to a semiconductor region of the second conductivity type, and may be composed of, for example, an impurity region of the first conductivity type having a lower impurity concentration than the first region 21.

[0048] In the embodiment, the wall-shaped electrode 24 may be mainly made of one selected from polysilicon, tungsten, and aluminum, which allows holes to be stably collected near the interface between the photodiode PD and the isolation region 23.

[0049] Therefore, according to the embodiment, it is possible to further suppress the occurrence of dark current and white spots in the photodiode PD.

[0050] In the embodiment, the wall-shaped electrodes 24 are preferably made of polysilicon, which can prevent the wall-shaped electrodes 24 from deteriorating even when the wall-shaped electrodes 24 are exposed to a high-temperature environment during the manufacturing process of the pixel array unit 10, which will be described later.

[0051] In addition, in the embodiment, it is preferable that the low absorption member 26 is mainly composed of one selected from silicon oxide, hafnium oxide, aluminum oxide, and titanium oxide. For example, by making the low absorption member 26 from silicon oxide, such a low absorption member 26 can be easily formed.

[0052] Furthermore, by making the low absorption member 26 from hafnium oxide, aluminum oxide, or titanium oxide, the difference in refractive index between the low absorption member 26 and the second region 22 made of silicon can be reduced.

[0053] Therefore, according to the embodiment, scattering of the light L can be suppressed at the end of the low absorption member 26 on the light incident side, and therefore deterioration of the light collection characteristics for the photodiode PD can be further suppressed.

[0054] Continuing with the description of other parts of the pixel array section 10, a wiring layer 30 is disposed on the opposite surface 20b of the semiconductor layer 20. The wiring layer 30 is configured by forming multiple layers of wiring 32 and multiple pixel transistors 33 within an interlayer insulating film 31.

[0055] The wiring 32 includes a wiring 32a electrically connected to the wall-like electrode 24. Furthermore, the plurality of pixel transistors 33 read out the electric charges accumulated in the photodiode PD.

[0056] An optical layer 40 is disposed on the light incident surface 20a of the semiconductor layer 20. The optical layer 40 includes a planarization film 41, a color filter 42, a light-shielding wall 43, and an OCL (On-Chip Lens) 44.

[0057] The planarization film 41 is provided to planarize the surface on which the color filters 42 and the OCL 44 are formed, and to prevent unevenness from occurring in the spin coating process when the color filters 42 and the OCL 44 are formed.

[0058] The planarization film 41 is made of, for example, an organic material (for example, acrylic resin). Note that the planarization film 41 is not limited to being made of an organic material, and may be made of silicon oxide, silicon nitride (SiN), or the like.

[0059] The color filter 42 is an optical filter that transmits light of a predetermined wavelength out of the light L collected by the OCL 44. The color filter 42 is disposed on the surface of the planarizing film 41 on the light incident side.

[0060] The color filters 42 include, for example, a color filter that transmits red light, a color filter that transmits green light, and a color filter that transmits blue light.

[0061] The light-shielding wall 43 is disposed, for example, between adjacent color filters 42. The light-shielding wall 43 is a wall-shaped film that blocks light that is obliquely incident from the adjacent color filter 42. The light-shielding wall 43 is made of, for example, aluminum or tungsten.

[0062] The OCL 44 is a lens provided for each light receiving pixel 11, and focuses the light L onto the photodiode PD of each light receiving pixel 11. The OCL 44 is made of, for example, an acrylic resin or the like.

[0063] [Pixel array manufacturing process] Next, a manufacturing process of the pixel array unit 10 according to the embodiment will be described with reference to Figures 3 to 8. Figures 3 to 8 are diagrams for explaining the manufacturing process of the pixel array unit 10 according to the embodiment of the present disclosure.

[0064] 3, in the manufacturing process of the pixel array unit 10, first, impurities of a second conductivity type are ion-implanted with high energy from the opposite surface 20b side of the semiconductor substrate 120, which contains impurities of a first conductivity type and will eventually become the semiconductor layer 20. As a result, a second region 22 is formed in a region deeper than a given depth X with respect to the opposite surface 20b.

[0065] At this time, a region of the semiconductor substrate 120 (semiconductor layer 20) closer to the opposite surface 20b than the second region 22 becomes the first region 21 of the first conductivity type.

[0066] Furthermore, a trench T1 is formed on the opposite surface 20b of the semiconductor substrate 120 (semiconductor layer 20) by a conventionally known method. The trench T1 is formed to penetrate the first region 21 and reach partway through the second region 22, and is formed in a portion where the separation region 23 is to be provided in plan view.

[0067] Next, as shown in FIG. 4, the trench T1 is filled with a low absorption member 26 from the bottom to a given depth X by a conventionally known method.

[0068] Next, as shown in FIG. 5, an insulating film 25 is formed on the side surface T1a of the trench T1 from a given depth X to the opening by a conventionally known method, and a wall-shaped electrode 24 is further formed by a conventionally known method so as to fill the remaining space of the trench T1.

[0069] 6, a wiring layer 30 is formed on the surface of the opposite surface 20b of the semiconductor substrate 120 (semiconductor layer 20). The wiring layer 30 is configured by providing multiple layers of wiring 32 and multiple pixel transistors 33 within an interlayer insulating film 31, and is formed by a conventionally known method.

[0070] 7, the surface of the semiconductor substrate 120 opposite to the opposite surface 20b is ground to thin the surface so as to expose the second region 22 and the low absorption member 26. This forms the semiconductor layer 20 and the light incident surface 20a.

[0071] Next, as shown in FIG. 8, on the surface of the light incident surface 20a of the semiconductor layer 20, a planarization film 41, a plurality of color filters 42, a plurality of light-shielding walls 43, and a plurality of OCLs 44 are formed in this order.

[0072] As described above, in the manufacturing process of the pixel array section 10 according to the embodiment, the isolation region 23 is formed by filling the trench T1 formed from the opposite surface 20b of the semiconductor layer 20 with a low-absorption member 26, an insulating film 25 and a wall-shaped electrode 24.

[0073] This allows the low absorption member 26, the insulating film 25, and the wall-like electrode 24 to be formed in a simple process, and also prevents misalignment between the low absorption member 26 and the wall-like electrode 24.

[0074] [Various variations] Next, various modifications of the embodiment will be described with reference to FIGS.

[0075] <Variation 1> 9 is a cross-sectional view schematically illustrating the structure of the pixel array section 10 according to Modification 1 of the embodiment of the present disclosure. Modification 1 differs from the above embodiment in the configuration of the low-absorption member 26 and its surroundings.

[0076] 9, in Modification 1, a fixed charge film 27 is disposed between the low absorption member 26 and the second region 22 and wall-like electrode 24. The fixed charge film 27 has the function of fixing charges (here, holes) at the interface between the separation region 23 and the second region 22.

[0077] A high-dielectric material having a large amount of fixed charge is preferably used as the material for the fixed charge film 27. The fixed charge film 27 is made of, for example, hafnium oxide, aluminum oxide, tantalum oxide, zirconium oxide (ZrO2), titanium oxide, magnesium oxide (MgO2), lanthanum oxide (La2O3), or the like.

[0078] The fixed charge film 27 may also be made of praseodymium oxide (Pr2O3), cerium oxide (CeO2), neodymium oxide (Nd2O3), promethium oxide (Pm2O3), samarium oxide (Sm2O3), europium oxide (Eu2O3), or the like.

[0079] The fixed charge film 27 may also be made of gadolinium oxide (Gd2O3), terbium oxide (Tb2O3), dysprosium oxide (Dy2O3), holmium oxide (Ho2O3), erbium oxide (Er2O3), thulium oxide (Tm2O3), or the like.

[0080] The fixed charge film 27 may also be made of ytterbium oxide (Yb2O3), lutetium oxide (Lu2O3), yttrium oxide (Y2O3), aluminum nitride (AlN), hafnium oxynitride (HfON), aluminum oxynitride film (AlON), or the like.

[0081] By arranging such a fixed charge film 27, in variant example 1, the generation of abnormal charges due to defects in the semiconductor layer 20 can be further suppressed near the interface between the low absorption member 26 and the second region 22, where no negative bias voltage is applied.

[0082] Therefore, according to the first modification, the occurrence of white spots in the photodiode PD can be further suppressed.

[0083] FIG. 10 is a diagram showing the relationship between the depth D at which the low absorption member 26 is disposed and the saturated charge amount of the light-sensitive pixel 11 in the first modification of the embodiment of the present disclosure.

[0084] 10 is data obtained from a simulation in which the fixed charge film 27 is made of a multilayer film of aluminum oxide and tantalum oxide, and the low absorption member 26 is made of silicon oxide. The reference example in FIG. 10 is data in which the low absorption member 26 and the fixed charge film 27 are not provided, and the wall-like electrode 24 penetrates the entire separation region 23.

[0085] 10, in Modification 1, it is more preferable that the low absorption member 26 is disposed to a depth D of 800 nm or more from the light incident surface 20a of the semiconductor layer 20. This makes it possible to greatly increase the amount of saturated charge compared to the reference example. That is, in Modification 1, by disposing the low absorption member 26 to a depth D of 800 nm or more, it is possible to further improve the light collection characteristics.

[0086] 10 is a result of simulating the configuration of Modified Example 1, but the results of simulating the configuration of the above embodiment are also similar to those of Fig. 10. That is, even in the above embodiment, the light-collecting characteristics can be further improved by arranging the low absorption member 26 to a depth D of 800 (nm) or more.

[0087] <Manufacturing Process of Modified Example 1> Next, a manufacturing process of the pixel array unit 10 according to Modification 1 will be described with reference to Figures 11 to 17. Figures 11 to 17 are diagrams for explaining the manufacturing process of the pixel array unit 10 according to Modification 1 of the embodiment of the present disclosure.

[0088] 11, in the manufacturing process of the first modification, first, impurities of the second conductivity type are ion-implanted with high energy from the opposite surface 20b side of the semiconductor substrate 120, which contains impurities of the first conductivity type and will eventually become the semiconductor layer 20. As a result, a second region 22 is formed in a region deeper than a given depth X with respect to the opposite surface 20b.

[0089] At this time, a region of the semiconductor substrate 120 (semiconductor layer 20) closer to the opposite surface 20b than the second region 22 becomes the first region 21 of the first conductivity type.

[0090] Furthermore, a trench T1 is formed by a conventionally known method on the opposite surface 20b of the semiconductor substrate 120 (semiconductor layer 20). The trench T1 is formed to penetrate the first region 21 and is formed in a portion where the isolation region 23 is to be provided in plan view.

[0091] Next, as shown in FIG. 12, an insulating film 25 is formed on the side surface T1a of the trench T1 from the bottom to the opening using a conventionally known method, and a wall-shaped electrode 24 is further formed using a conventionally known method so as to fill the remaining space of the trench T1.

[0092] 13, a wiring layer 30 is formed on the surface of the opposite surface 20b of the semiconductor substrate 120 (semiconductor layer 20). The wiring layer 30 is configured by providing multiple layers of wiring 32 and multiple pixel transistors 33 in an interlayer insulating film 31, and is formed by a conventionally known method.

[0093] 14, the surface of the semiconductor substrate 120 opposite to the opposite surface 20b is ground to be thinned so as to expose the second region 22. This forms the semiconductor layer 20 and the light incident surface 20a.

[0094] 15, a trench T2 is formed by a conventionally known method on the light incident surface 20a side of the semiconductor layer 20. The trench T2 is formed to penetrate the second region 22 and is formed in a portion where the separation region 23 is to be provided in plan view. That is, the trench T2 is formed so as to expose the wall-shaped electrode 24 and the insulating film 25 at the bottom.

[0095] Next, as shown in FIG. 16, a fixed charge film 27 is formed on the side surface T2a and bottom surface T2b of the trench T2 by a conventionally known method, and further, a low absorption member 26 is formed by a conventionally known method so as to fill the remaining space of the trench T2.

[0096] Next, as shown in FIG. 17, a planarizing film 41, a plurality of color filters 42, a plurality of light-shielding walls 43, and a plurality of OCLs 44 are formed in this order on the surface of the light-incident surface 20a of the semiconductor layer 20.

[0097] Thus, in the manufacturing process of variant example 1, the trench T1 formed from the opposite surface 20b is filled with an insulating film 25 and a wall-shaped electrode 24, and the trench T2 formed from the light incident surface 20a is filled with a fixed charge film 27 and a low-absorption member 26, thereby forming the separation region 23.

[0098] Therefore, according to the first modification, the low absorption member 26 is not exposed to a high-temperature environment during the process of forming the wiring layer 30, and therefore, deterioration of the low absorption member 26 can be suppressed.

[0099] In the manufacturing process of the above-described embodiment and variant example 1, an example is shown in which the first region 21 and the second region 22 are formed by ion-implanting second conductivity type impurities into the first conductivity type semiconductor substrate 120 with high energy, but the present disclosure is not limited to such an example.

[0100] For example, in the technique of the present disclosure, the first region 21 and the second region 22 may be formed by ion-implanting a first conductivity type impurity with relatively low energy from the opposite surface 20b side of the second conductivity type semiconductor substrate 120.

[0101] <Variation 2> 18 is a cross-sectional view schematically illustrating the structure of the pixel array section 10 according to Modification 2 of the embodiment of the present disclosure. Modification 2 differs from Modification 1 above in the configuration of the second region 22.

[0102] Specifically, as shown in FIG. 18, in the second modification, the second region 22 has a first portion 22a arranged on the first region 21 side and a second portion 22b arranged on the light incident surface 20a side.

[0103] The first portion 22a is a region having a lower impurity concentration than the first region 21, and is, for example, a first conductivity type impurity region having a lower impurity concentration than the first region 21. The second portion 22b is a region having a lower impurity concentration than the first portion 22a, and is, for example, a second conductivity type impurity region.

[0104] This also makes it possible to further suppress the generation of abnormal charges due to defects in the semiconductor layer 20 near the interface between the low absorption member 26, to which no negative bias voltage is applied, and the second region 22. Therefore, according to the second modification, the generation of white spots in the photodiode PD can be further suppressed.

[0105] <Variation 3> 19 is a cross-sectional view schematically illustrating the structure of the pixel array section 10 according to Modification 3 of the embodiment of the present disclosure. Modification 3 differs from Modification 1 above in the configuration around the low-absorption member 26.

[0106] 19, in Modification 3, a stopper film 28 is disposed between the low absorption member 26 and the fixed charge film 27 and the wall-like electrode 24 and the insulating film 25. The stopper film 28 is formed so as to fill the bottom of the trench T1 after the trench T1 is formed and before the insulating film 25 and the wall-like electrode 24 are formed in the manufacturing process shown in FIG.

[0107] The stopper film 28 is made of a material (such as silicon oxide or silicon nitride) that has a high etching selectivity with respect to the material of the semiconductor layer 20 (such as silicon).

[0108] In the third modification, by disposing such a stopper film 28, the stopper film 28 can be used as an etching stopper in the step of forming the trench T2 shown in Fig. 15. Therefore, according to the third modification, the trench T2 can be formed with high precision.

[0109] <Variation 4> 20 is a cross-sectional view schematically illustrating the structure of the pixel array section 10 according to Modification 4 of the embodiment of the present disclosure. In Modification 4, the sizes of the low absorption member 26 and the fixed charge film 27 are different from those of Modification 1 described above.

[0110] Specifically, as shown in FIG. 20, in the fourth modification, the wall-like portion formed by the low absorption member 26 and the fixed charge film 27 is thicker than the wall-like portion formed by the wall-like electrode 24 and the insulating film 25. In the fourth modification, as shown in FIG.

[0111] As a result, even if the trench T2 is misaligned with respect to the trench T1 during the formation process of the trench T2, the wall-like portion formed by the low absorption member 26 and the fixed charge film 27 can be connected to the wall-like portion formed by the wall-like electrode 24 and the insulating film 25.

[0112] Therefore, according to the fourth modification, even if the trench T2 is misaligned with respect to the trench T1, the adjacent photodiodes PD can be reliably isolated by the isolation region 23.

[0113] <Variation 5> 21 is a cross-sectional view schematically illustrating the structure of the pixel array section 10 according to Modification 5 of the embodiment of the present disclosure. Modification 5 differs from Modification 1 above in the configurations of the low absorption member 26 and the fixed charge film 27.

[0114] 21, in Modification 5, the low absorption member 26A is made of a conductive material (for example, tungsten or aluminum), and the fixed charge film 27A is made of an insulating material (for example, silicon oxide). Also, in Modification 5, the low absorption member 26A and the wall-like electrode 24 are electrically connected to each other.

[0115] As a result, a negative bias voltage is also applied to the low absorption member 26A via the wall-like electrode 24, and holes can be collected also near the interface between the second region 22 and the separation region 23. Therefore, according to the fifth modification, it is possible to further suppress the occurrence of dark current and white spots in the photodiode PD.

[0116] <Variation 6> Fig. 22 is a diagram showing a planar configuration of a pixel array section 10 according to Modification 6 of the embodiment of the present disclosure. Fig. 23 is a cross-sectional view taken along line AA in Fig. 22, and Fig. 24 is a cross-sectional view taken along line BB in Fig. 22.

[0117] 22 and other figures, in the pixel array section 10 of Modification 6, a pair of photodiodes PD (hereinafter also referred to as photodiodes PD1 and PD2) is provided in one light receiving pixel 11. For example, the light receiving pixel 11 has a substantially square shape in a plan view, and the photodiode PD has a substantially rectangular shape in a plan view.

[0118] Furthermore, the light receiving pixel 11 has a first isolation region 23a, a second isolation region 23b, and an impurity region 23c as the isolation region 23. As shown in FIG. 22, the first isolation region 23a is arranged so as to surround the pair of photodiodes PD1 and PD2 in one light receiving pixel 11.

[0119] The second isolation region 23b is disposed between a pair of adjacent photodiodes PD1 and PD2 in one light-receiving pixel 11. The second isolation region 23b optically and electrically isolates the pair of adjacent photodiodes PD1 and PD2.

[0120] That is, in the light-receiving pixel 11 of the sixth modification, the first isolation region 23a separates the photodiodes PD on which light L is incident via different OCLs 44. The second isolation region 23b separates the pair of photodiodes PD1 and PD2 on which light L is incident via the same OCL 44.

[0121] In this way, in variant 6, the pair of photodiodes PD1 and PD2 can be separated from each other using the second isolation region 23b, and therefore the phase difference of the incident light L can be detected using the pair of photodiodes PD1 and PD2.

[0122] The impurity region 23c is disposed between the pair of photodiodes PD1 and PD2 at a position different from the second isolation region 23b in plan view, and contains impurities of the second conductivity type.

[0123] The impurity region 23c functions as an overflow path between the photodiode PD1 and the photodiode PD2, thereby making it possible in the sixth modification to equalize the amount of charge stored in both the photodiodes PD1 and PD2.

[0124] Here, in the sixth modification, as shown in FIG. 23, similar to the first modification, the first isolation region 23a and the second isolation region 23b have a wall-shaped electrode 24, an insulating film 25, a low absorption member 26, and a fixed charge film 27.

[0125] As a result, in variant example 6, it is possible to impart good separation characteristics to the first separation region 23a and the second separation region 23b, and to suppress absorption of light L in the light incident side portions of the first separation region 23a and the second separation region 23b.

[0126] Therefore, according to the sixth modification, in the light-receiving pixel 11 that can detect the phase difference of the light L, it is possible to suppress deterioration of the light-collection characteristics of the pair of photodiodes PD1 and PD2.

[0127] In addition, in variant example 6, as shown in Figure 23, the depth D2 at which the low absorption member 26 and the fixed charge film 27 are arranged in the second isolation region 23b is preferably deeper than the depth D1 at which the low absorption member 26 and the fixed charge film 27 are arranged in the first isolation region 23a.

[0128] As a result, since the second separation region 23b is positioned near the optical axis of the OCL 44, it is possible to effectively prevent light L from being absorbed in the area on the light incident side in the second separation region 23b, which collects more light L than the first separation region 23a.

[0129] Therefore, according to the sixth modification, in the light-receiving pixel 11 that can detect the phase difference of the light L, it is possible to further suppress deterioration of the light-collection characteristics of the pair of photodiodes PD1 and PD2.

[0130] In the examples of FIGS. 22 to 24, a phase difference pixel in which an overflow path (impurity region 23c) is arranged between a pair of photodiodes PD1 and PD2 is shown, but the present disclosure is not limited to such an example.

[0131] For example, in a phase difference pixel in which a pair of photodiodes PD1 and PD2 are completely separated by a second separation region 23b, the first separation region 23a and the second separation region 23b may have a wall-shaped electrode 24, an insulating film 25, a low absorption member 26, and a fixed charge film 27.

[0132] This makes it possible to suppress deterioration of the light-collecting characteristics of the pair of photodiodes PD1 and PD2 in the light-receiving pixel 11 that can detect the phase difference of the light L.

[0133] Furthermore, in this phase difference pixel, the depth D2 at which the low absorption member 26 and the fixed charge film 27 are arranged in the second isolation region 23b may be deeper than the depth D1 at which the low absorption member 26 and the fixed charge film 27 are arranged in the first isolation region 23a. This makes it possible to further suppress deterioration of the light-collecting characteristics of the pair of photodiodes PD1 and PD2.

[0134] [effect] The solid-state imaging element 1 according to the embodiment includes a semiconductor layer 20 and an isolation region 23. The semiconductor layer 20 has a plurality of photoelectric conversion units (photodiodes PD) arranged in a matrix. The isolation region 23 separates adjacent photoelectric conversion units (photodiodes PD) in the semiconductor layer 20. The isolation region 23 also has a wall-like electrode 24 and a low absorption member 26. The wall-like electrode 24 is arranged in a wall shape, and a negative bias voltage is applied to the wall-like electrode 24. The low absorption member 26 is arranged closer to the light incident side than the wall-like electrode 24, and has a lower light absorption rate than the wall-like electrode 24.

[0135] This makes it possible to suppress deterioration of the light-collecting characteristics of the photodiode PD.

[0136] In the solid-state imaging device 1 according to the embodiment, the photoelectric conversion unit (photodiode PD) has a first region 21 adjacent to the wall-shaped electrode 24 and a second region 22 adjacent to the low absorption member 26. The impurity concentration of the second region 22 is lower than the impurity concentration of the first region 21.

[0137] This makes it possible to suppress the occurrence of white spots in the photodiode PD.

[0138] In the solid-state imaging device 1 according to the embodiment, the low absorption member 26 is disposed to a depth D of 800 (nm) or more from the surface 20a of the semiconductor layer 20 on the light incident side.

[0139] This makes it possible to further improve the light-collecting characteristics for the photodiode PD.

[0140] In the solid-state imaging device 1 according to the embodiment, the wall-shaped electrodes 24 are mainly made of one material selected from polysilicon, tungsten, and aluminum.

[0141] This makes it possible to further suppress the occurrence of dark current and white spots in the photodiode PD.

[0142] In the solid-state imaging device 1 according to the embodiment, the low-absorption member 26 is mainly composed of one material selected from silicon oxide, hafnium oxide, aluminum oxide, and titanium oxide.

[0143] This allows the low absorption member 26 to be easily formed, or makes it possible to suppress scattering of the light L at the end of the low absorption member 26 on the light incident side.

[0144] The solid-state imaging device 1 according to the embodiment further includes a plurality of on-chip lenses (OCLs 44) that allow light L to be incident on corresponding photoelectric conversion units (photodiodes PD). The isolation region 23 includes a first isolation region 23a and a second isolation region 23b. The first isolation region 23a separates the plurality of photoelectric conversion units (photodiodes PD) onto which light L is incident via different on-chip lenses (OCLs 44). The second isolation region 23b separates the plurality of photoelectric conversion units (photodiodes PD) onto which light L is incident via the same on-chip lens (OCLs 44). The low absorption members 26 located in the second isolation region 23b are disposed to a deeper position than the low absorption members 26 located in the first isolation region 23a.

[0145] This makes it possible to further suppress deterioration of the light-collecting characteristics of the pair of photodiodes PD1 and PD2 in the light-receiving pixel 11 that can detect the phase difference of the light L.

[0146] Furthermore, the manufacturing method of the solid-state imaging device 1 according to the embodiment includes the steps of forming a trench T1, filling the trench with a low-absorption member 26, forming an insulating film 25, and filling the trench with a wall-shaped electrode 24. In the step of forming the trench T1, the trench T1 is formed on the surface 20b opposite the light incident side of the semiconductor substrate 120. In the step of filling the trench with the low-absorption member 26, the trench is filled with the low-absorption member 26 from the bottom to a given depth X. In the step of forming the insulating film 25, the insulating film 25 is formed on the side surface T1a of the trench T1 from the given depth X to the opening. In the step of filling the trench with the wall-shaped electrode 24, the remaining portion of the trench T1 is filled with the conductive wall-shaped electrode 24. In addition, the wiring 32a formed in the wiring layer 30 is connected to the wall-shaped electrode 24, and the low-absorption member 26 has a lower light absorption rate than the wall-shaped electrode 24.

[0147] This makes it possible to easily form the solid-state imaging device 1 in which deterioration of the light-collecting characteristics for the photodiode PD is suppressed, and also makes it possible to prevent misalignment between the low absorption member 26 and the wall-like electrode 24.

[0148] The manufacturing method of the solid-state imaging device 1 according to the embodiment further includes a step of reducing the impurity concentration in a region from a depth corresponding to the bottom of the trench T1 to a given depth X, the impurity concentration of which is lower than that of a region from the given depth X to the surface 20b of the semiconductor substrate 120 opposite to the light incident side.

[0149] This makes it possible to form a solid-state imaging device 1 in which the occurrence of white spots in the photodiodes PD is suppressed.

[0150] [Electronic equipment] Note that the present disclosure is not limited to application to solid-state imaging elements, and can be applied to all electronic devices that have solid-state imaging elements, such as camera modules, imaging devices, portable terminal devices with imaging functions, and copiers that use solid-state imaging elements in their image reading units.

[0151] Examples of such imaging devices include digital still cameras and video cameras, while examples of mobile terminal devices with imaging capabilities include smartphones and tablet terminals.

[0152] Fig. 25 is a block diagram showing a configuration example of an imaging device serving as electronic device 1000 to which the technology according to the present disclosure is applied. Electronic device 1000 in Fig. 25 is, for example, an imaging device such as a digital still camera or a video camera, or a mobile terminal device such as a smartphone or a tablet terminal.

[0153] In FIG. 25, electronic device 1000 comprises a lens group 1001 , a solid-state imaging device 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 .

[0154] In the electronic device 1000 , the DSP circuit 1003 , frame memory 1004 , display unit 1005 , recording unit 1006 , operation unit 1007 , and power supply unit 1008 are interconnected via a bus line 1009 .

[0155] The lens group 1001 captures incident light (image light) from a subject and forms an image on the imaging surface of the solid-state imaging element 1002. The solid-state imaging element 1002 corresponds to the solid-state imaging element 1 according to the above-described embodiment, and 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 outputs the signal as a pixel signal.

[0156] The DSP circuit 1003 is a camera signal processing circuit that processes signals supplied from the solid-state image sensor 1002. The frame memory 1004 temporarily stores image data processed by the DSP circuit 1003 on a frame-by-frame basis.

[0157] 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 moving or still images captured by the solid-state imaging element 1002. The recording unit 1006 records image data of the moving or still images captured by the solid-state imaging element 1002 on a recording medium such as a semiconductor memory or a hard disk.

[0158] In response to user operations, the operation unit 1007 issues operation commands for the various functions of the electronic device 1000. The power supply unit 1008 appropriately supplies various types of power to the DSP circuit 1003, frame memory 1004, display unit 1005, recording unit 1006, and operation unit 1007 as operating power sources.

[0159] In the electronic device 1000 configured as above, by applying the solid-state imaging element 1 of each of the above-described embodiments as the solid-state imaging element 1002, it is possible to suppress deterioration of the light-collecting characteristics of the photodiode PD.

[0160] [Application to mobile devices] 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 moving 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.

[0161] FIG. 26 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.

[0162] The vehicle control system 12000 includes a plurality of electronic control units connected via a communication network 12001. In the example shown in Fig. 26, 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.

[0163] 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, a braking device for generating a braking force of the vehicle, etc.

[0164] 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 may 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.

[0165] 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.

[0166] 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 invisible light such as infrared light.

[0167] 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.

[0168] 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 drivetrain 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 collisions between vehicles, following based on the distance between vehicles, maintaining vehicle speed, warning of vehicle collisions, or warning of vehicle lane departure.

[0169] 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.

[0170] Furthermore, the microcomputer 12051 can output a control command to the body system control unit 12020 based on the information about the outside of 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 for the purpose of preventing glare, such as switching from high beams to low beams.

[0171] 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 information to passengers in the vehicle or to the outside of the vehicle. In the example of Fig. 26, 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.

[0172] FIG. 27 is a diagram showing an example of the installation position of the imaging unit 12031.

[0173] In FIG. 27, the imaging unit 12031 includes imaging units 12101, 12102, 12103, 12104, and 12105.

[0174] 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 at the front nose and the imaging unit 12105 provided at 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 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 top of the windshield inside the vehicle cabin is mainly used to detect preceding vehicles, pedestrians, obstacles, traffic lights, traffic signs, lanes, etc.

[0175] 27 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, a bird's-eye view image of the vehicle 12100 viewed from above can be obtained.

[0176] 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 made up of multiple imaging elements, or may be an imaging element having pixels for phase difference detection.

[0177] For example, 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) based on the distance information obtained from the imaging units 12101 to 12104, 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 (for example, 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 automatic driving, which runs autonomously without relying on driver operation.

[0178] 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 then determines the collision risk, which indicates the degree of 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 drivetrain control unit 12010.

[0179] 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 or not a pedestrian is present in the images captured by the image capturing units 12101 to 12104. The pedestrian recognition is performed, for example, by extracting feature points from the images captured by the image capturing units 12101 to 12104, which are infrared cameras, and then performing pattern matching on a series of feature points that indicate the outline 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 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.

[0180] 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 the imaging unit 12031 in the configuration described above. Specifically, the solid-state imaging element 1 in FIG. 1 can be applied to the imaging unit 12031. By applying the technology according to the present disclosure to the imaging unit 12031, high-quality images can be acquired from the imaging unit 12031.

[0181] Although the embodiments of the present disclosure have been described above, the technical scope of the present disclosure is not limited to the above-described embodiments, and various modifications are possible within the scope of the gist of the present disclosure. Furthermore, components of different embodiments and modifications may be combined as appropriate.

[0182] Furthermore, the effects described in this specification are merely examples and are not limiting, and other effects may also be present.

[0183] The present technology can also be configured as follows. (1) a semiconductor layer having a plurality of photoelectric conversion units arranged in a matrix; an isolation region that isolates adjacent photoelectric conversion units from each other in the semiconductor layer; Equipped with The separation region is a wall-shaped electrode disposed in a wall shape and to which a negative bias voltage is applied; a low-absorption member that is disposed on the light incident side of the wall-shaped electrode and has a lower light absorption rate than the wall-shaped electrode; A solid-state imaging element having (2) the photoelectric conversion section has a first region adjacent to the wall-shaped electrode and a second region adjacent to the low absorption member, The impurity concentration of the second region is lower than the impurity concentration of the first region. The solid-state imaging device according to (1) above. (3) The low absorption member is disposed to a depth of 800 nm or more from the light incident surface of the semiconductor layer. The solid-state imaging device according to (1) or (2) above. (4) The wall-shaped electrode is mainly composed of one material selected from polysilicon, tungsten, and aluminum. The solid-state imaging device according to any one of (1) to (3) above. (5) The low-absorption member is mainly composed of one selected from silicon oxide, hafnium oxide, aluminum oxide, and titanium oxide. The solid-state imaging device according to any one of (1) to (4) above. (6) a plurality of on-chip lenses that allow light to be incident on the corresponding photoelectric conversion units; Furthermore, The separation region is a first isolation region that isolates the plurality of photoelectric conversion units to which light is incident via different on-chip lenses; a second isolation region that isolates the plurality of photoelectric conversion units to which light is incident via the same on-chip lens; and The low-absorbency member located in the second separation region is disposed to a deeper position than the low-absorbency member located in the first separation region. The solid-state imaging device according to any one of (1) to (5) above. (7) forming a trench on a surface of a semiconductor substrate opposite to a light incident side; Filling the trench from the bottom to a given depth with a low-absorption material; forming an insulating film on a side surface of the trench from the given depth to an opening; filling the remaining portion of the trench with a conductive wall electrode; forming a wiring layer on a light incident side surface of the semiconductor substrate; Including, a wiring formed in the wiring layer is connected to the wall-like electrode; The low absorption member has a lower light absorption rate than the wall-shaped electrode. A method for manufacturing a solid-state imaging device. (8) The method further includes a step of making the impurity concentration in a region from a depth corresponding to the bottom of the trench to the given depth lower than that in a region from the given depth to a surface of the semiconductor substrate opposite to the light incident side. A method for manufacturing a solid-state imaging device according to (7) above. (9) a solid-state imaging element; an optical system that captures incident light from a subject and forms an image on an imaging surface of the solid-state imaging device; a signal processing circuit that processes an output signal from the solid-state imaging device, The solid-state imaging device is a semiconductor layer having a plurality of photoelectric conversion units arranged in a matrix; an isolation region that isolates adjacent photoelectric conversion units from each other in the semiconductor layer; and The separation region is a wall-shaped electrode disposed in a wall shape and to which a negative bias voltage is applied; a low-absorption member that is disposed on the light incident side of the wall-shaped electrode and has a lower light absorption rate than the wall-shaped electrode; An electronic device having: (10) the photoelectric conversion section has a first region adjacent to the wall-shaped electrode and a second region adjacent to the low absorption member, The impurity concentration of the second region is lower than the impurity concentration of the first region. The electronic device according to (9) above. (11) The low absorption member is disposed to a depth of 800 nm or more from the light incident surface of the semiconductor layer. The electronic device according to (9) or (10) above. (12) The wall-shaped electrode is mainly composed of one material selected from polysilicon, tungsten, and aluminum. The electronic device according to any one of (9) to (11) above. (13) The low-absorption member is mainly composed of one selected from silicon oxide, hafnium oxide, aluminum oxide, and titanium oxide. The electronic device according to any one of (9) to (12) above. (14) a plurality of on-chip lenses that allow light to be incident on the corresponding photoelectric conversion units; Furthermore, The separation region is a first isolation region that isolates the plurality of photoelectric conversion units to which light is incident via different on-chip lenses; a second isolation region that isolates the plurality of photoelectric conversion units to which light is incident via the same on-chip lens; and The low-absorbency member located in the second separation region is disposed to a deeper position than the low-absorbency member located in the first separation region. The electronic device according to any one of (9) to (13) above. [Explanation of symbols]

[0184] 1. Solid-state imaging element 10 Pixel array section 11 photosensitive pixels 20 Semiconductor layer 21 First area 22 Second area 23 Separation area 23a 1st separation area 23b 2nd separation area 24 wall electrode 25 insulating film 26, 26A Low absorption material 27, 27A fixed charge membrane 30 wiring layer 32, 32a wiring 1000 electronic equipment PD, PD1, PD2 Photodiodes (examples of photoelectric conversion units)

Claims

1. a semiconductor layer having a plurality of photoelectric conversion units arranged in a matrix; an isolation region that isolates adjacent photoelectric conversion units from each other in the semiconductor layer; Equipped with The separation region is a wall-shaped electrode disposed in a wall shape and to which a negative bias voltage is applied; a low-absorption member that is disposed on the light incident side of the wall-shaped electrode and has a lower light absorption rate than the wall-shaped electrode; and the photoelectric conversion portion has a first region adjacent to the wall-shaped electrode and a second region adjacent to the low absorption member, The impurity concentration of the second region is lower than the impurity concentration of the first region. Solid-state imaging element.

2. The low absorption member is disposed to a depth of 800 nm or more from the light incident surface of the semiconductor layer. The solid-state imaging device according to claim 1 .

3. The wall-shaped electrode is mainly composed of one material selected from polysilicon, tungsten, and aluminum.

3. The solid-state imaging device according to claim 1.

4. The low-absorption member is mainly composed of one selected from silicon oxide, hafnium oxide, aluminum oxide, and titanium oxide.

4. The solid-state imaging device according to claim 1.

5. A semiconductor layer having a plurality of photoelectric conversion units arranged in a matrix; an isolation region that isolates adjacent photoelectric conversion units from each other in the semiconductor layer; a plurality of on-chip lenses that allow light to be incident on the corresponding photoelectric conversion units; Equipped with The separation region is a wall-shaped electrode disposed in a wall shape and to which a negative bias voltage is applied; a low-absorption member that is disposed on the light incident side of the wall-shaped electrode and has a lower light absorption rate than the wall-shaped electrode; a first isolation region that isolates the plurality of photoelectric conversion units to which light is incident via different on-chip lenses; a second isolation region that isolates the plurality of photoelectric conversion units to which light is incident via the same on-chip lens; and The low-absorbency member located in the second separation region is disposed to a deeper position than the low-absorbency member located in the first separation region. Solid-state imaging element.

6. forming a trench on a surface of a semiconductor substrate opposite to a light incident side; Filling the trench from the bottom to a given depth with a low-absorption material; forming an insulating film on a side surface of the trench from the given depth to an opening; filling the remaining portion of the trench with a conductive wall electrode; forming a wiring layer on a light incident side surface of the semiconductor substrate; Including, a wiring formed in the wiring layer is connected to the wall-like electrode; the low absorption member has a lower light absorption rate than the wall-shaped electrode, The method further includes a step of making the impurity concentration in a region from a depth corresponding to the bottom of the trench to the given depth lower than that in a region from the given depth to a surface of the semiconductor substrate opposite to the light incident side. A method for manufacturing a solid-state imaging device.

7. a solid-state imaging element; an optical system that captures incident light from a subject and forms an image on an imaging surface of the solid-state imaging device; a signal processing circuit that processes an output signal from the solid-state imaging device, The solid-state imaging device is a semiconductor layer having a plurality of photoelectric conversion units arranged in a matrix; an isolation region that isolates adjacent photoelectric conversion units from each other in the semiconductor layer; and The separation region is a wall-shaped electrode disposed in a wall shape and to which a negative bias voltage is applied; a low-absorption member that is disposed on the light incident side of the wall-shaped electrode and has a lower light absorption rate than the wall-shaped electrode; and the photoelectric conversion portion has a first region adjacent to the wall-shaped electrode and a second region adjacent to the low absorption member, The impurity concentration of the second region is lower than the impurity concentration of the first region. electronic equipment.

8. A solid-state imaging element; an optical system that captures incident light from a subject and forms an image on an imaging surface of the solid-state imaging device; a signal processing circuit that processes an output signal from the solid-state imaging device, The solid-state imaging device is a semiconductor layer having a plurality of photoelectric conversion units arranged in a matrix; an isolation region that isolates adjacent photoelectric conversion units from each other in the semiconductor layer; a plurality of on-chip lenses that allow light to be incident on the corresponding photoelectric conversion units; and The separation region is a wall-shaped electrode disposed in a wall shape and to which a negative bias voltage is applied; a low-absorption member that is disposed on the light incident side of the wall-shaped electrode and has a lower light absorption rate than the wall-shaped electrode; a first isolation region that isolates the plurality of photoelectric conversion units to which light is incident via different on-chip lenses; a second isolation region that isolates the plurality of photoelectric conversion units to which light is incident via the same on-chip lens; and The low-absorbency member located in the second separation region is disposed to a deeper position than the low-absorbency member located in the first separation region. electronic equipment.

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