Image capture device, production method for same, and electronic apparatus

Abstract

The present technology relates to: an image capture device that has multi–photoelectric conversion element pixels and achieves both improved sensitivity and reduced color mixing; a production method for the image capture device; and an electronic apparatus. According to the present invention, a semiconductor substrate has a two-dimensional array of pixels that have a plurality of photoelectric conversion elements. A color filter is formed on the semiconductor substrate at each photoelectric conversion element. A protective film is formed on the color filters. A lens is formed on the protective film at each photoelectric conversion element. A top surface and a bottom surface of the lenses have the same shape. Inter-pixel separation parts that are formed between the photoelectric conversion elements of adjacent pixels and / or inter-pixel wall parts that are formed between the color filters have portions that protrude toward the center of the pixels to form protruding parts. The present technology can be applied, for example, to CMOS image sensors.

Description

Imaging device, manufacturing method thereof, and electronic device

[0001] The present technology relates to an imaging device, a manufacturing method thereof, and an electronic device, and in particular to an imaging device having a plurality of photoelectric conversion element pixels that can achieve both improved sensitivity and reduced occurrence of color mixing, a manufacturing method thereof, and an electronic device.

[0002] In recent years, imaging devices have been proposed in which a convex lens is not formed as an on-chip lens on each pixel (see, for example, Patent Document 1).

[0003] International Publication No. 2023 / 042447

[0004] However, in such imaging devices, uncondensed light enters the pixel. Therefore, when the pixel is a multi-photoelectric conversion element pixel, it is difficult to achieve both improved sensitivity (Qe) and reduced color mixing. A multi-photoelectric conversion element pixel is a pixel having multiple photoelectric conversion elements. At least one of the inter-pixel separators formed between the photoelectric conversion elements of adjacent multi-photoelectric conversion element pixels and the inter-pixel wall portions formed between the color filters protrudes toward the center of the pixel to form a protrusion.

[0005] For these reasons, there is a demand for a method that can improve sensitivity and reduce the occurrence of color mixing in an imaging device having multiple photoelectric conversion element pixels, but this demand has not yet been fully met.

[0006] The present technology has been made in consideration of such circumstances, and makes it possible to achieve both improved sensitivity and reduced occurrence of color mixing in an imaging device having multiple photoelectric conversion element pixels.

[0007] An imaging device or electronic device according to a first aspect of the present technology is an imaging device or electronic device equipped with an imaging device, which includes: a semiconductor substrate on which pixels, each having a plurality of photoelectric conversion elements, are two-dimensionally arranged; a color filter formed on the semiconductor substrate for each of the photoelectric conversion elements; a protective film formed on the color filter; and a lens, the top and bottom of which have the same shape, formed on the protective film for each of the photoelectric conversion elements, wherein at least one of an inter-pixel separation portion formed between the photoelectric conversion elements of adjacent pixels and an inter-pixel wall portion formed between the color filters has a part that protrudes in a protruding shape toward the center of the pixel, thereby forming a protrusion.

[0008] In a first aspect of the present technology, a semiconductor substrate is provided on which pixels each having a plurality of photoelectric conversion elements are two-dimensionally arranged, a color filter is formed on the semiconductor substrate for each of the photoelectric conversion elements, a protective film is formed on the color filter, and a lens having the same shape on its top and bottom surfaces is formed on the protective film for each of the photoelectric conversion elements, wherein at least one of an inter-pixel separation portion formed between the photoelectric conversion elements of adjacent pixels and an inter-pixel wall portion formed between the color filters protrudes in a protruding shape toward the center of the pixel to form a protrusion.

[0009] A manufacturing method of a second aspect of the present technology is a manufacturing method for an imaging device that includes forming a protective film on color filters formed for each photoelectric conversion element on a semiconductor substrate on which pixels having a plurality of photoelectric conversion elements are two-dimensionally arranged, and forming lenses having the same shapes for their top and bottom surfaces on the protective film for each photoelectric conversion element, wherein at least one of inter-pixel separation portions formed between the photoelectric conversion elements of adjacent pixels and inter-pixel wall portions formed between the color filters has a part that protrudes in a protruding manner toward the center of the pixel, thereby forming a protrusion.

[0010] In a second aspect of the present technology, a protective film is formed on a semiconductor substrate on which pixels each having a plurality of photoelectric conversion elements are two-dimensionally arranged, the protective film is formed on the color filters formed for each of the photoelectric conversion elements, and a lens having the same shape on its top and bottom surfaces is formed on the protective film for each of the photoelectric conversion elements. Note that at least one of an inter-pixel separation portion formed between the photoelectric conversion elements of adjacent pixels and an inter-pixel wall portion formed between the color filters has a part that protrudes in a protruding shape toward the center of the pixel to form a protrusion.

[0011] 10 is a diagram illustrating an example of a circuit configuration of a CMOS image sensor that is a first embodiment of an imaging device to which the present technology is applied. FIG. 11 is a cross-sectional view showing an example of a configuration of a pixel array unit. FIG. 12 is a cross-sectional view showing an example of a structure of the CMOS image sensor of FIG. 1. FIG. 13 is a top view showing an example of a shape of the upper surface of a lens. FIG. 14 is a view explaining a first step of a manufacturing method in the first embodiment. FIG. 15 is a view explaining a second step of a manufacturing method in the first embodiment. FIG. 16 is a view explaining a third step of a manufacturing method in the first embodiment. FIG. 17 is a view explaining a fourth step of a manufacturing method in the first embodiment. FIG. 18 is a view explaining a fifth step of a manufacturing method in the first embodiment. FIG. 19 is a view explaining a sixth step of a manufacturing method in the first embodiment. FIG. 19 is an enlarged view of a rectangle S in FIG. 10. FIG. 11 is a cross-sectional view showing another example of a configuration of an inter-pixel wall portion. FIG. 12 is a cross-sectional view showing another example of a cross-sectional shape of a lens. FIG. 13 is a top view showing another example of a shape of the upper surface of a lens. FIG. 14 is a cross-sectional view showing an example of a structure of a CMOS image sensor that is a second embodiment of an imaging device to which the present technology is applied. FIG. 15 is a view explaining a third step of a manufacturing method in the second embodiment. FIG. 16 is a view explaining a fourth step of a manufacturing method in the second embodiment. FIG. 17 is a block diagram showing an example of a configuration of a digital camera as an electronic device to which the present technology is applied. FIG. 18 is a block diagram showing an example of a schematic configuration of a vehicle control system. FIG. 2 is an explanatory diagram showing an example of an installation position of an imaging unit.

[0012] Hereinafter, modes for carrying out the present technology (hereinafter referred to as embodiments) will be described. The description will be made in the following order: 1. First embodiment (CMOS image sensor having a lens and a protective film) 2. Second embodiment (CMOS image sensor having a resin film between a lens and a protective film) 3. Application example to electronic devices 4. Application example to mobile objects

[0013] In the drawings referred to in the following description, the same or similar parts are denoted by the same or similar reference numerals. However, the drawings are schematic, and the relationship between thickness and planar dimensions, the thickness ratio of each layer, etc. may differ from the actual ones. Furthermore, the drawings may include parts whose dimensional relationships and ratios differ from each other.

[0014] Furthermore, the definitions of directions such as up and down in the following description are merely for the convenience of explanation and do not limit the technical idea of ​​the present disclosure. For example, if an object is rotated 90 degrees and observed, up and down are converted to left and right and read, and if it is rotated 180 degrees and observed, up and down are read inverted.

[0015] 1. First Embodiment Example of a Circuit Configuration of a CMOS Image Sensor FIG. 1 is a diagram showing an example of a circuit configuration of a CMOS (Complementary Metal Oxide Semiconductor) image sensor that is a first embodiment of an imaging device to which the present technology is applied.

[0016] 1 is formed on a semiconductor substrate. The CMOS image sensor 10 converts the amount of incident light that is incident from a subject through an optical lens system (not shown) and forms an image on the imaging surface of the semiconductor substrate into an electrical signal for each photoelectric conversion element, and outputs the electrical signal.

[0017] The CMOS image sensor 10 includes a pixel array section 11 , a vertical drive circuit 12 , a column signal processing circuit 13 , a horizontal drive circuit 14 , an output circuit 15 , a control circuit 16 , and an input / output terminal 17 .

[0018] The pixel array unit 11 is configured by a plurality of photoelectric conversion element pixels 100 arranged two-dimensionally (in a matrix). Each pixel 100 has a photoelectric conversion element such as two photodiodes, and converts incident light into an electric charge on a photoelectric conversion element basis. Each pixel 100 also has a pixel circuit that generates an electric signal based on the electric charge converted by each photoelectric conversion element and outputs the electric signal to a vertical signal line 22 (described later).

[0019] In the pixel array section 11, pixel drive lines 21 that transmit control signals to the pixel circuits are arranged for each row of pixels 100, and the pixels 100 in the same row are connected to the same pixel drive line 21. In addition, in the pixel array section 11, vertical signal lines 22 that transmit electrical signals generated by the pixel circuits for each column of pixels 100 are arranged, and the same vertical signal line 22 is connected to the pixels 100 in the same column.

[0020] The vertical drive circuit 12 is configured by, for example, a shift register. The vertical drive circuit 12 sequentially selects pixel drive lines 21 and supplies drive signals for driving pixel circuits to the selected pixel drive lines 21. As a result, the pixel circuits of the pixels 100 to which the drive signals are supplied via the pixel drive lines 21 generate electrical signals for each photoelectric conversion element and output them to vertical signal lines 22.

[0021] The column signal processing circuit 13 has a circuit for each column of pixels 100. Each circuit is connected to a vertical signal line 22, and performs predetermined signal processing on the electrical signal of each photoelectric conversion element supplied via the vertical signal line 22. Examples of this signal processing include correlated double sampling and AD (Analog-Digital) conversion for removing fixed pattern noise specific to each pixel.

[0022] The horizontal drive circuit 14 is configured by, for example, a shift register. The horizontal drive circuit 14 sequentially selects each circuit of the column signal processing circuit 13 and supplies a horizontal scanning signal to the selected circuit. As a result, each circuit of the column signal processing circuit 13 outputs an electrical signal after signal processing to a horizontal signal line 23.

[0023] The output circuit 15 performs predetermined processing on the electrical signals sequentially supplied from each circuit of the column signal processing circuit 13 via the horizontal signal line 23, and outputs the processed signals. This processing includes buffering, black level adjustment, column variation correction, various digital signal processing, etc. The electrical signals output from the output circuit 15 for each photoelectric conversion element are used for phase difference detection and for generating a captured image.

[0024] The control circuit 16 controls the entire CMOS image sensor 10. Specifically, the control circuit 16 generates clock signals and control signals that serve as references for the operations of the vertical drive circuit 12, the column signal processing circuit 13, and the horizontal drive circuit 14. The control circuit 16 outputs the generated clock signals and control signals to the vertical drive circuit 12, the column signal processing circuit 13, and the horizontal drive circuit 14.

[0025] The input / output terminal 17 exchanges signals with the outside.

[0026] <Configuration Example of Pixel Array Section> FIG. 2 is a cross-sectional view showing a configuration example of the pixel array section 11 of FIG. 1, taken along a plane parallel to the imaging surface of a semiconductor substrate on which the CMOS image sensor 10 is formed.

[0027] In FIG. 2, 4×4 (4 rows and 4 columns) pixels 100 are shown as representative examples of the plurality of pixels 100 arranged two-dimensionally in the pixel array section 11 .

[0028] 2 is a Bayer array. Specifically, for every 2×2 pixels 100, the colors of the color filters formed on the upper left pixel 100, the upper right pixel 100, the lower left pixel 100, and the lower right pixel 100 are red (R), green (G), green (G), and blue (B), respectively.

[0029] Each pixel 100 has two photoelectric conversion elements 112a and 112b that are physically separated by impurities 111 formed in the column direction within the semiconductor substrate. Hereinafter, unless there is a need to distinguish between the photoelectric conversion elements 112 and 112b, they will be collectively referred to as the photoelectric conversion element 112. Of two adjacent pixels 100, the photoelectric conversion element 112b of one pixel 100 and the photoelectric conversion element 112a of the other pixel 100 are physically separated within the semiconductor substrate by inter-pixel isolation portions 115 that are arranged in a grid pattern. The inter-pixel isolation portions 115 are formed of an oxide film, metal, or the like.

[0030] In each pixel 100, a portion of the inter-pixel separation portion 115 is formed so as to protrude in a protruding manner toward the center of the pixel 100. In the following description, this protruding portion is referred to as a protruding portion 115P. This protruding portion 115P can improve the accuracy of phase difference detection while suppressing a decrease in sensitivity and an increase in the occurrence of color mixing. Details of the protruding portion 115P are described in, for example, Japanese Patent Application Laid-Open No. 2018-201015.

[0031] 2, the protrusions 115P are formed in all the pixels 100, but the protrusions 115P may be formed only in the pixels 100 having a color filter of a predetermined color. The arrangement of the pixels 100 may be an arrangement other than the Bayer arrangement.

[0032] <Structural Example of CMOS Image Sensor> FIG. 3 is a cross-sectional view perpendicular to the imaging surface of the semiconductor substrate, showing a structural example of the CMOS image sensor 10 of FIG.

[0033] In Figure 3, in order to simplify the illustration, only the two pixels 100 at the center (center of the optical axis) of the CMOS image sensor 10 and a portion of the area of ​​each of the two pixels 100 and the two adjacent pixels 100 on the side away from the center are shown.

[0034] 3, the CMOS image sensor 10 is a back-illuminated CMOS image sensor, and therefore, in the CMOS image sensor 10, a wiring layer 131 is formed on the surface of the semiconductor substrate 130 opposite to the imaging surface (light incident surface).

[0035] The semiconductor substrate 130 is made of, for example, a silicon substrate. A pixel array section 11 is formed on the semiconductor substrate 130. Specifically, pixels 100, each of which includes photoelectric conversion elements 112a and 112b and a pixel circuit (not shown), are formed in a matrix on the semiconductor substrate 130. Of two adjacent pixels 100, an inter-pixel isolation section 115 is formed between the photoelectric conversion element 112b of one pixel 100 and the photoelectric conversion element 112a of the other pixel 100. A protrusion 115P is formed between the photoelectric conversion elements 112a and 112b within the same pixel 100.

[0036] Wiring such as pixel drive lines 21, vertical signal lines 22, and power supply lines Vdd are formed in the wiring layer 131. The wiring layer 131 and the pixel circuits are connected by via plugs. The wiring layer 131 is configured with multiple layers, and each layer is also connected by via plugs. The wiring of the wiring layer 131 can be made of metal such as Al or Cu. The via plug can be made of metal such as W or Cu. SiO2 or the like can be used to insulate the wiring layer 131.

[0037] An insulating film 132 made of SiO, SiON, SiN, or the like is formed on the semiconductor substrate 130. A color filter layer 133 is formed on the insulating film 132. In the color filter layer 133, color filters 151 that selectively transmit light of a predetermined color for each photoelectric conversion element 112 are formed. The color filters 151 of the photoelectric conversion elements 112a and 112b that constitute the same pixel 100 have the same color. Between adjacent color filters 151, inter-pixel walls 152 made of gaps with a lower refractive index than the color filters 151 are formed.

[0038] A protective film 134 (blocking film) is formed on the color filter 133 layer. Materials for the protective film 134 include SiO, SiON, SiN, etc., and it is desirable for the protective film 134 to have a refractive index close to that of the color filter 151. The optical path length through the thickness of the protective film 134 is desirably 1 / 2 the wavelength of the incident light. When the optical path length through the thickness of the protective film 134 is 1 / 2 the wavelength of the incident light, and the incident light is visible light with a wavelength of 400 nm to 700 nm, the optical path length through the thickness of the protective film 134 is greater than 200 nm (= 400 / 2) and less than 350 nm (= 700 / 2). For example, in this case, when the material of the protective film 134 is SiO, which has a refractive index n of 1.47, the thickness of the protective film 134 is approximately 136 nm (= 400 / (2 × 1.47)) to approximately 238 nm (= 700 / (2 × 1.47)).

[0039] An etch stop film 135 made of AlO or the like is formed on the protective film 134 .

[0040] A lens layer 136 is formed on the etch stop film 135. In the lens layer 136, lenses 161 having an upper surface 161a and a bottom surface 161b with the same shape are formed for each photoelectric conversion element 112. In the example of Fig. 3, the cross section of the lens 161 is rectangular. The lens 161 can be made of a material such as SiO, SiON, SiN, or a resin material.

[0041] The optical path length through the thickness of lens 161 is preferably ¼ of the wavelength of the incident light. When the optical path length through the thickness of lens 161 is ¼ of the wavelength of the incident light, and the incident light is visible light with a wavelength of 400 nm to 700 nm, the optical path length through the thickness of lens 161 is greater than 100 nm (= 400 / 4) and less than 175 nm (= 700 / 4). For example, in this case, when lens 161 is made of SiO with a refractive index n of 1.47, the thickness of lens 161 is approximately 68 nm (= 400 / (4 × 1.47)) to approximately 119 nm (= 700 / (4 × 1.47)). When the incident light is visible light, color filter 151 is preferably thicker than lens 161.

[0042] <Examples of Shape of Upper Surface of Lens> FIG. 4 is a top view of the CMOS image sensor 10, showing examples of the shape of the upper surface 161a of the lens 161. In FIG.

[0043] In FIG. 4, 2×2 lenses 161 formed in a partial region of the plurality of lenses 161 formed for each photoelectric conversion element 112 in the CMOS image sensor 10 are shown as a representative example.

[0044] In the example of Fig. 4A, the shape of the top surface 161a of the lens 161 is rectangular. In the example of Fig. 4B, the shape of the top surface 161a of the lens 161 is circular. In the example of Fig. 4C, the shape of the top surface 161a of the lens 161 is octagonal. Although not shown, the shapes of the top surface 161a and the bottom surface 161b are the same. The shapes of the top surface 161a and the bottom surface 161b of the lens 161 are not limited to the shapes of Figs. 4A to 4C, and can be any shape, such as a polygon other than a rectangle or an octagon.

[0045] <Description of Manufacturing Method> FIGS. 5 to 10 are diagrams illustrating a manufacturing method for the color filter layer 133, the protective film 134, the etch stop film 135, and the lens 161. FIG.

[0046] Fig. 5A and Fig. 6A are top views of the region of adjacent 2 x 2 photoelectric conversion elements 112 at the center of 2 x 2 pixels 100 of the CMOS image sensor 10. Fig. 5B, Fig. 6B, and Figs. 7 to 10 are cross-sectional views of the region from the center to the outer periphery of the CMOS image sensor 10. In Fig. 5B, Fig. 6B, and Figs. 7 to 10, the left side is the center side, and the right side is the outer periphery side.

[0047] 5A and 5B, in the first step, a color filter layer 133 is formed by temporary wall removal wet etching on the imaging surface of the semiconductor substrate 130 on which the wiring layer 131 has been formed, on the side opposite the wiring layer 131. As a result, an SiO layer 201 is formed on the color filter layer 133. The thickness of this SiO layer 201 is, for example, 60 nm.

[0048] The CMOS image sensor 10 has a pupil correction function. Therefore, as shown in Fig. 5B, the horizontal position of the color filter 151 deviates from the horizontal position of the photoelectric conversion element 112 corresponding to that color filter 151 as it moves away from the center of the CMOS image sensor 10. Fig. 5A shows the color filter 151 in a see-through manner.

[0049] 6A and 6B, a protective film 134 is formed on the color filter layer 133 by chemical vapor deposition (CVD) of, for example, 100 nm of TEOS (tetra ethoxy silane). As a result, for example, a 130 nm SiO film is formed as the protective film 134 on the color filter layer 133.

[0050] 7, an etch stop film 135 is formed on the protective film 134. In a fourth step, as shown in Fig. 8, a lens film 202 made of the material of the lens 161 is formed on the etch stop film 135. The lens film 202 is, for example, an LTO (SiO) film.

[0051] In the fifth step, as shown in Fig. 9 , a resist 203 is applied by lithography to the region on the lens film 202 where the lens 161 is to be formed. As described above, the CMOS image sensor 10 has a pupil correction function. Therefore, as shown in Fig. 9 , the horizontal position of the resist 203 corresponding to the lens 161 shifts from the horizontal position of the photoelectric conversion element 112 corresponding to that lens 161 with increasing distance from the center of the CMOS image sensor 10.

[0052] In the sixth step, the lens film 202 is removed by dry etching from the area where the resist 203 is not formed. At this time, since the etch stop film 135 is formed below the lens film 202, the dry etching is stopped by this etch stop film 135. After the dry etching, the resist 203 is removed, thereby forming the lens 161 as shown in FIG.

[0053] <Details of Etch Stop Film> FIG. 11 is an enlarged view of the rectangle S in FIG. 10 for explaining the details of the etch stop film 135. As shown in FIG.

[0054] In the sixth step, the etch stop film 135 is also etched by dry etching together with the lens film 202 in the region where the resist 203 is not formed. As a result, as shown in FIG. 11 , the thickness of the etch stop film 135 in the region where the lens 161 is not formed is thinner than the thickness of the etch stop film 135 below the lens 161.

[0055] <Another Configuration Example of Inter-Pixel Wall> FIG. 12 is a cross-sectional view showing another configuration example of the inter-pixel wall 152. In FIG.

[0056] In FIG. 12, parts corresponding to those in FIG. 2 are denoted by the same reference numerals.

[0057] In the example of FIG. 12A, the inter-pixel wall portion 152 is composed of a gap portion 231 and a barrier metal layer 232 formed on the inter-pixel wall portion 152 on the semiconductor substrate 130 side.

[0058] 12B, the inter-pixel wall portion 152 is configured, instead of the void portion 231, by a low refractive index layer 241 made of a material with a lower refractive index than the color filter 151, and a barrier metal layer 242 formed on the semiconductor substrate 130 side of the inter-pixel wall portion 152. Examples of materials for the barrier metal layers 232 and 242 include Ti and TiN.

[0059] 12C, the inter-pixel wall portion 152 is formed by forming, in order from the semiconductor substrate 130 side, a W (tungsten) layer 251 and a SiO layer 252. In the example of Fig. 12D, the inter-pixel wall portion 152 is formed by a W layer 261 formed only on a part of the semiconductor substrate 130 side between adjacent color filters 151.

[0060] <Other Examples of Lens Cross-Sectional Shapes> FIG. 13 is a cross-sectional view showing another example of the cross-sectional shape of the lens 161. In FIG.

[0061] In FIG. 13, parts corresponding to those in FIG. 3 are given the same reference numerals.

[0062] In the example of Figure 13, the upper surface of the color filter layer 133 is not flat. As a result, the upper surfaces of the protective film 134 formed on the color filter layer 133 and the etch stop film 135 formed on the protective film 134 are not flat. Therefore, the cross-sectional shape of the lens 161 formed on the upper surface of the etch stop film 135 is not rectangular. However, the shapes of the upper surface 161a and the bottom surface 161b of the lens 161 are the same. Although not shown in the figure, the corners of the lens 161 may be rounded.

[0063] <Other Shape Examples of the Upper Surface of the Lens> FIG. 14 is a top view of the CMOS image sensor 10, showing other shape examples of the upper surface 161a of the lens 161. In FIG.

[0064] In Fig. 14, the same reference numerals are used for the parts corresponding to those in Fig. 4. Fig. 14 shows, as a representative example, 4 × 4 lenses 161 formed in a partial region of the multiple lenses 161 formed for each photoelectric conversion element 112 in the CMOS image sensor 10.

[0065] 14, the shapes of the upper surfaces 161a of the 4×4 lenses 161 are all rectangular, but the sizes are different. Specifically, the sizes of the upper surfaces 161a of the 2×2 lenses 161 at the top left and bottom right of the 4×4 lenses 161 are larger than the sizes of the upper surfaces 161a of the 2×2 lenses 161 at the top right and bottom left.

[0066] Although not shown in the figures, the size of the lenses 161 and the spacing between adjacent lenses 161 may be changed for each color of the color filter 151 corresponding to the lens 161 or for each image height.

[0067] As described above, the CMOS image sensor 10 includes a semiconductor substrate 130 on which a plurality of photoelectric conversion element pixels, that is, pixels 100, are two-dimensionally arranged. A color filter 151 is formed for each photoelectric conversion element 112 on the semiconductor substrate 130, and a lens 161 is formed for each photoelectric conversion element 112 on the color filter 151. Therefore, light collected by the lens 161 is incident on the pixel 100.

[0068] As a result, it is possible to achieve both improved sensitivity and reduced color mixing in the CMOS image sensor 10 having the pixel 100, which is a pixel having multiple photoelectric conversion elements. Also, it is possible to improve the separation ratio of the electrical signals corresponding to the photoelectric conversion elements 112a and 112b at high image heights compared to a CMOS image sensor having an on-chip lens that is taller and has a higher curvature than the lens 161. Furthermore, it is possible to improve the separation ratio of the electrical signals corresponding to the photoelectric conversion elements 112a and 112b at the center of the image height compared to a CMOS image sensor having an on-chip lens or a CMOS image sensor having no lens.

[0069] In the CMOS image sensor 10, a protective film 134 is formed between the color filter 151 and the lens 161. This prevents degradation of the spectral characteristics due to decomposition of the material of the color filter 151, thereby improving the reliability of the CMOS image sensor 10.

[0070] In the CMOS image sensor 10, an etch stop film 135 is formed between the protective film 134 and the lens 161. Therefore, when the lens 161 is formed by dry etching, the protective film 134 in the area where the lens 161 is not formed can be prevented from being dry etched. Also, the reliability of the CMOS image sensor 10 can be improved.

[0071] 2. Second Embodiment <Structural Example of CMOS Image Sensor> FIG. 15 is a cross-sectional view perpendicular to the imaging surface of a semiconductor substrate, showing a structural example of a CMOS image sensor that is a second embodiment of an imaging device to which the present technology is applied.

[0072] In Figure 15, in order to simplify the illustration, only the two central pixels 100 of the CMOS image sensor 300 and a portion of the area of ​​each of the two pixels 100 adjacent to the two pixels 100 on the side away from the center are shown.

[0073] In the CMOS image sensor 300 in Fig. 15, parts corresponding to those in the CMOS image sensor 10 in Fig. 3 are denoted by the same reference numerals. Therefore, the description of those parts will be omitted as appropriate, and the description will focus on parts that differ from the CMOS image sensor 10. The CMOS image sensor 300 in Fig. 15 differs from the CMOS image sensor 10 in that a resin layer 301 is formed on the protective film 134, but is otherwise configured in the same way as the CMOS image sensor 10.

[0074] The resin layer 301 is made of STSR or the like, and is formed between the protective film 134 and the etch stop film 135 .

[0075] <Description of Manufacturing Method> FIGS. 16 and 17 are diagrams illustrating a manufacturing method of the resin layer 301 and the etch stop film 135. FIG.

[0076] 16 and 17 are cross-sectional views of the region from the center to the outer periphery of the CMOS image sensor 300. In Fig. 16 and Fig. 17, the left side is the center side and the right side is the outer periphery side.

[0077] 5 and 6 are performed, in a third step, the protective film 134 is planarized, and a resin material is applied onto the protective film 134 to form a resin layer 301, as shown in Fig. 16. In a fourth step, an etch stop film 135 is formed on the resin layer 301, as shown in Fig. 17.

[0078] After the fourth step, the fourth to sixth steps described with reference to FIGS. 8 to 10 are carried out, and a lens layer 136 is formed on the etch stop film 135 .

[0079] As described above, the CMOS image sensor 300, like the CMOS image sensor 10, includes the semiconductor substrate 130 on which the pixels 100 are two-dimensionally arranged, the color filter 151, the protective film 134, the etch stop film 135, and the lens 161. Therefore, the CMOS image sensor 300 can have the same effects as the CMOS image sensor 10.

[0080] The etch stop film 135 does not have to be formed in the CMOS image sensor 300. In this case, the dry etching performed when forming the lens 161 stops at the resin layer 301. Therefore, it is possible to prevent the protective film 134 in the area where the lens 161 is not formed from being dry etched.

[0081] In the CMOS image sensor 10 (300), the inter-pixel separator 115 has the protrusion 115P, but at least one of the inter-pixel separator 115 and the inter-pixel wall 152 may have a protrusion.

[0082] When the inter-pixel wall portion 152 has a protrusion, the color filters 151 of adjacent pixels 100 are separated by the inter-pixel wall portion 152 arranged in a grid pattern. Specifically, of two adjacent pixels 100, the inter-pixel wall portion 152 is formed between the color filter 151 corresponding to the photoelectric conversion element 112b of one pixel 100 and the color filter 151 corresponding to the photoelectric conversion element 112a of the other pixel 100. In each pixel 100, a part of the inter-pixel wall portion 152 is formed so as to protrude in a protruding manner toward the center of the pixel 100. The protruding portion, which is the protruding portion, separates the color filters 151 corresponding to the photoelectric conversion elements 112a and 112b within the same pixel 100.

[0083] Like the protrusion 115P, the protrusion of the inter-pixel wall portion 152 may not be formed for all the pixels 100, but may be formed only for the pixels 100 having a color filter 151 of a predetermined color.

[0084] 3. Application Examples to Electronic Devices The above-described CMOS image sensor 10 (300) can be applied to various electronic devices, such as digital cameras such as digital still cameras and digital video cameras, and mobile phones with imaging functions.

[0085] FIG. 18 is a block diagram showing an example configuration of a digital camera as an electronic device to which the present technology is applied.

[0086] The digital camera 1001 shown in Figure 18 is configured with an optical system 1002, a shutter device 1003, a solid-state image sensor 1004, a control circuit 1005, a signal processing circuit 1006, a monitor 1007, and a memory 1008, and is capable of capturing still images and moving images.

[0087] The optical system 1002 is configured with one or more lenses, and guides light from a subject (incident light) to the solid-state image sensor 1004 to form an image on the light-receiving surface of the solid-state image sensor 1004 .

[0088] The shutter device 1003 is disposed between the optical system 1002 and the solid-state image sensor 1004 , and controls the light irradiation period and light blocking period for the solid-state image sensor 1004 under the control of the control circuit 1005 .

[0089] The solid-state imaging element 1004 is configured by the above-mentioned CMOS image sensor 10 (300). The solid-state imaging element 1004 accumulates signal charges for a certain period of time in response to light that is imaged on the light-receiving surface via the optical system 1002 and the shutter device 1003. The signal charges accumulated in the solid-state imaging element 1004 are transferred in accordance with a drive signal (timing signal) supplied from the control circuit 1005.

[0090] The control circuit 1005 outputs a drive signal that controls the transfer operation of the solid-state image sensor 1004 and the shutter operation of the shutter device 1003 , thereby driving the solid-state image sensor 1004 and the shutter device 1003 .

[0091] The signal processing circuit 1006 performs various signal processing on the signal charges output from the solid-state imaging device 1004. The image (image data) obtained by the signal processing performed by the signal processing circuit 1006 is supplied to a monitor 1007 for display, or supplied to a memory 1008 for storage (recording).

[0092] The digital camera 1001 configured in this manner can also achieve the above-described effects by applying the CMOS image sensor 10 (300) as the solid-state imaging element 1004. Specifically, for example, in a solid-state imaging element 1004 having a plurality of photoelectric conversion element pixels, it is possible to achieve both improved sensitivity and reduced color mixing.

[0093] 4. Application Examples to Mobile Bodies 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.

[0094] FIG. 19 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.

[0095] The vehicle control system 12000 includes a plurality of electronic control units connected via a communication network 12001. In the example shown in Fig. 19, 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.

[0096] 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.

[0097] 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.

[0098] 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.

[0099] 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.

[0100] 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.

[0101] 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.

[0102] 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.

[0103] 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.

[0104] 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. 19, 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.

[0105] FIG. 20 is a diagram showing an example of the installation position of the imaging unit 12031.

[0106] In FIG. 20 , a vehicle 12100 has imaging units 12101, 12102, 12103, 12104, and 12105 as an imaging unit 12031.

[0107] 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.

[0108] 20 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.

[0109] 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.

[0110] 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.

[0111] 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 a collision risk that 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.

[0112] 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.

[0113] The foregoing describes an example of a vehicle control system to which the technology according to the present disclosure can be applied. The technology according to the present disclosure can be applied to the imaging unit 12031 of the above-described configuration. Specifically, the CMOS image sensor 10 (300) can be applied to the imaging unit 12031. By applying the technology according to the present disclosure to the imaging unit 12031, it is possible to improve sensitivity and reduce color mixing in the imaging unit 12031 having multiple photoelectric conversion element pixels. As a result, it is possible to obtain a captured image that is easier to see, thereby reducing driver fatigue.

[0114] The embodiments of the present technology are not limited to the above-described embodiments, and various modifications are possible without departing from the spirit of the present technology.

[0115] For example, it is possible to adopt a configuration in which all or part of the above-described embodiments are combined.

[0116] The effects described in this specification are merely examples and are not intended to be limiting, and there may be effects other than those described in this specification.

[0117] The present technology can have the following configurations. (1) An imaging device including: a semiconductor substrate on which pixels, each having a plurality of photoelectric conversion elements, are two-dimensionally arranged; a color filter formed on the semiconductor substrate for each of the photoelectric conversion elements; a protective film formed on the color filter; and a lens, the top and bottom of which have the same shape, formed on the protective film for each of the photoelectric conversion elements, wherein at least one of an inter-pixel separator formed between the photoelectric conversion elements of adjacent pixels and an inter-pixel wall formed between the color filters has a part that protrudes in a protruding shape toward the center of the pixel to form a protrusion. (2) The imaging device according to (1), wherein the cross-sectional shape of the lens is rectangular. (3) The imaging device according to (1) or (2), wherein the optical path length through the thickness of the protective film is ½ the wavelength of incident light. (4) The imaging device according to any of (1) to (3), wherein the optical path length through the thickness of the lens is ¼ the wavelength of incident light. (5) The imaging device according to any one of (1) to (4), wherein the optical path length of the thickness of the protective film is greater than 200 nm and less than 350 nm. (6) The imaging device according to any one of (1) to (5), wherein the optical path length of the thickness of the lens is greater than 100 nm and less than 175 nm. (7) The imaging device according to any one of (1) to (6), wherein the color filter is thicker than the lens. (8) The imaging device according to any one of (1) to (7), wherein the inter-pixel wall portion is composed of a gap, a material having a lower refractive index than the color filter, SiO, or W. (9) The imaging device according to any one of (1) to (7), wherein the inter-pixel wall portion is composed of a gap or a material having a lower refractive index than the color filter, and a barrier metal layer formed on the semiconductor substrate side of the inter-pixel wall portion. (10) The imaging device according to any one of (1) to (9), further comprising an etch stop film formed between the lens and the protective film.(11) The imaging device according to any one of (1) to (10), further comprising a resin layer formed between the protective film and the lens. (12) A method for manufacturing an imaging device, comprising: forming a protective film on a color filter formed for each photoelectric conversion element on a semiconductor substrate on which pixels having a plurality of photoelectric conversion elements are two-dimensionally arranged, and forming a lens having the same shape for its top and bottom surfaces on the protective film for each photoelectric conversion element, wherein at least one of an inter-pixel separation portion formed between the photoelectric conversion elements of adjacent pixels and an inter-pixel wall portion formed between the color filters has a part that protrudes in a protruding shape toward the center of the pixel to form a protrusion. (13) An electronic device equipped with an imaging device comprising: a semiconductor substrate on which pixels, each having a plurality of photoelectric conversion elements, are two-dimensionally arranged; a color filter formed on the semiconductor substrate for each of the photoelectric conversion elements; a protective film formed on the color filter; and a lens, the top and bottom of which have the same shape, formed on the protective film for each of the photoelectric conversion elements, wherein at least one of an inter-pixel separation portion formed between the photoelectric conversion elements of adjacent pixels and an inter-pixel wall portion formed between the color filters has a part that protrudes in a protruding shape toward the center of the pixel to form a protrusion.

[0118] 10 CMOS image sensor, 112a, 112b photoelectric conversion element, 115 inter-pixel separation portion, 115P protrusion portion, 130 semiconductor substrate, 134 protective film, 135 etch stop film, 136 lens, 151 color filter, 152 inter-pixel wall portion, 231 gap portion, 232 barrier metal layer, 241 low refractive index layer, 242 barrier metal layer, 251 W layer, 252 SiO layer, 261 W layer, 300 CMOS image sensor, 301 resin layer, 1001 digital camera, 1004 solid-state imaging element

Claims

1. An imaging device comprising: a semiconductor substrate on which pixels, each having a plurality of photoelectric conversion elements, are arranged in a two-dimensional array; a color filter formed on the semiconductor substrate for each of the photoelectric conversion elements; a protective film formed on the color filter; and a lens, the top and bottom of which have the same shape, formed on the protective film for each of the photoelectric conversion elements, wherein at least one of an inter-pixel separation portion formed between the photoelectric conversion elements of adjacent pixels and an inter-pixel wall portion formed between the color filters has a part that protrudes in a protruding manner toward the center of the pixel to form a protrusion.

2. The imaging device according to claim 1, wherein the cross-sectional shape of the lens is rectangular.

3. The imaging device according to claim 1, wherein the optical path length of the thickness of the protective film is configured to be 1 / 2 the wavelength of the incident light.

4. The imaging device according to claim 1, wherein the optical path length of the thickness of the lens is configured to be 1 / 4 of the wavelength of the incident light.

5. The imaging device according to claim 1, wherein the optical path length of the thickness of the protective film is greater than 200 nm and less than 350 nm.

6. The imaging device according to claim 1, wherein the optical path length of the thickness of the lens is greater than 100 nm and smaller than 175 nm.

7. The imaging device according to claim 1, wherein the color filter is thicker than the lens.

8. The imaging device according to claim 1, wherein the inter-pixel wall portion is made of a void portion, a material having a lower refractive index than the color filter, SiO, or W.

9. The imaging device according to claim 1, wherein the inter-pixel wall portion is composed of a material having a lower refractive index than the void portion or the color filter, and a barrier metal layer formed on the semiconductor substrate side of the inter-pixel wall portion.

10. The imaging device according to claim 1, further comprising an etch stop film formed between the lens and the protective film.

11. The imaging device according to claim 1, further comprising a resin layer formed between the protective film and the lens.

12. A method for manufacturing an imaging device comprising: forming a protective film on a color filter formed for each photoelectric conversion element on a semiconductor substrate on which pixels having a plurality of photoelectric conversion elements are two-dimensionally arranged; and forming a lens having the same shape for its top and bottom on the protective film for each photoelectric conversion element, wherein at least one of an inter-pixel separation portion formed between the photoelectric conversion elements of adjacent pixels and an inter-pixel wall portion formed between the color filters has a part that protrudes in a protruding manner toward the center of the pixel to form a protrusion.

13. An electronic device equipped with an imaging device comprising: a semiconductor substrate on which pixels, each having a plurality of photoelectric conversion elements, are arranged in a two-dimensional array; a color filter formed on the semiconductor substrate for each of the photoelectric conversion elements; a protective film formed on the color filter; and a lens having the same shape for its top and bottom surfaces formed on the protective film for each of the photoelectric conversion elements, wherein at least one of an inter-pixel separation portion formed between the photoelectric conversion elements of adjacent pixels and an inter-pixel wall portion formed between the color filters has a part that protrudes in a protruding manner toward the center of the pixel to form a protrusion.

Images