Imaging device, method of manufacturing same, and electronic apparatus

Abstract

The present technology relates to: an imaging device having a plurality of photoelectric conversion element pixels while improving sensitivity and reducing the occurrence of color mixing; a method for manufacturing an imaging device; and an electronic device. According to the present invention, pixels are two-dimensionally arranged on a semiconductor substrate, and each pixel has a plurality of photoelectric conversion elements. A color filter is formed on the semiconductor substrate for each of the photoelectric conversion elements. The protective film is formed on the color filter. A lens is formed on the protective film for each of the photoelectric conversion elements. The upper surface and the lower surface of the lens have the same shape. At least one of an inter-pixel separation portion formed between the photoelectric conversion elements of adjacent pixels and a pixel partition wall portion formed between the color filters has a portion protruding toward the center of the pixel with a formed protruding portion. The present technology can be applied, for example, to a CMOS image sensor.

Description

Technical Field

[0001] This technology relates to camera devices, manufacturing methods thereof, and electronic devices, and particularly to camera devices, manufacturing methods thereof, and electronic devices that can simultaneously improve sensitivity and reduce color mixing in camera devices including pixels with multiple photoelectric conversion elements. Background Technology

[0002] In recent years, a camera device has been designed in which a convex lens as an on-chip lens is not formed on each pixel (see, for example, Patent Document 1). Citation List Patent documents

[0003] Patent Document 1: WO 2023 / 042447 Summary of the Invention Technical issues

[0004] However, in this imaging device, unfocused light enters the pixel. Therefore, when the pixel is a multi-electro-conversion element pixel, it is difficult to simultaneously improve sensitivity (Qe) and reduce color mixing. Note that a multi-electro-conversion element pixel is a pixel comprising multiple photoelectric conversion elements. At least a portion of at least one of the inter-pixel separation portion formed between the photoelectric conversion elements of adjacent multi-electro-conversion element pixels and the pixel wall portion formed between color filters protrudes in a convex manner toward the center of the pixel to form a protrusion.

[0005] As mentioned above, there is a need for a technology that can simultaneously improve sensitivity and reduce color mixing in a camera device that includes pixels with multiple photoelectric conversion elements, but this need has not yet been fully met.

[0006] This technology was developed in view of the above circumstances and aims to simultaneously improve sensitivity and reduce color mixing in a camera device that includes pixels with multiple photoelectric conversion elements. Solution to the problem

[0007] The imaging device or electronic device according to the first aspect of the present technology is an imaging device or an electronic device equipped with an imaging device, the imaging device comprising: a semiconductor substrate on which pixels are arranged in two dimensions, each pixel including a plurality of photoelectric conversion elements; a color filter formed on the semiconductor substrate in a manner corresponding to the photoelectric conversion elements respectively; a protective film formed on the color filter; and a lens formed on the protective film for each photoelectric conversion element, the upper and lower surfaces of the lens having the same shape, wherein a portion of at least one of the inter-pixel separation portion formed between the photoelectric conversion elements of adjacent pixels and the inter-pixel wall portion formed between the color filters protrudes in a protruding manner toward the center of each pixel and forms a protrusion.

[0008] In a first aspect of this technology, a semiconductor substrate is provided having pixels arranged in a two-dimensional pattern thereon, each pixel including a plurality of photoelectric conversion elements; color filters formed on the semiconductor substrate in a manner corresponding to the photoelectric conversion elements respectively; a protective film formed on the color filters; and a lens formed on the protective film for each photoelectric conversion element, the upper and lower surfaces of the lens having the same shape. A portion of at least one of an inter-pixel separation portion formed between the photoelectric conversion elements of adjacent pixels and a portion of an inter-pixel wall formed between the color filters protrudes in a protruding manner toward the center of each pixel, forming a protrusion.

[0009] A manufacturing method according to a second aspect of the present technology is a method for manufacturing an imaging device, the method comprising: forming a protective film on a color filter formed on a semiconductor substrate, wherein pixels are arranged in two dimensions on the semiconductor substrate, each pixel including a plurality of photoelectric conversion elements, the color filter being formed in such a manner corresponding to the photoelectric conversion elements respectively; and forming a lens on the protective film for each photoelectric conversion element, the upper surface and lower surface of the lens having the same shape, wherein a portion of 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 toward the center of each pixel in a protruding manner, and forming a protrusion.

[0010] In a second aspect of this technology, a protective film is formed on a color filter formed on a semiconductor substrate, on which pixels are arranged in a two-dimensional pattern. Each pixel includes a plurality of photoelectric conversion elements, and the color filter is formed in such a manner that it corresponds to each photoelectric conversion element. A lens is formed on the protective film for each photoelectric conversion element, and the upper and lower surfaces of the lens have the same shape. Note that at least a portion of at least one of the inter-pixel separation portion formed between the photoelectric conversion elements of adjacent pixels and the inter-pixel wall portion formed between the color filters protrudes towards the center of each pixel in a protruding manner, forming a protrusion. Attached Figure Description

[0011] Figure 1 This is a diagram illustrating an example of the circuit construction of a CMOS image sensor, which is a first embodiment of a camera device to which this technology is applied. Figure 2 This is a cross-sectional view showing an example of the construction of the pixel array section. Figure 3 It is shown Figure 1 A cross-sectional view of an example structure of a CMOS image sensor. Figure 4 Includes a top view showing an example of the shape of the upper surface of the lens. Figure 5 The diagram includes a figure illustrating the first step of the manufacturing method according to the first embodiment. Figure 6 The diagram includes a figure illustrating the second step of the manufacturing method according to the first embodiment. Figure 7 This is a diagram illustrating the third step of the manufacturing method according to the first embodiment. Figure 8 This is a diagram illustrating the fourth step of the manufacturing method according to the first embodiment. Figure 9 This is a diagram illustrating the fifth step of the manufacturing method according to the first embodiment. Figure 10 This is a diagram illustrating the sixth step of the manufacturing method according to the first embodiment. Figure 11 yes Figure 10 An enlarged view of rectangle S in the image. Figure 12 Includes cross-sectional views showing other structural examples of pixel partitions. Figure 13 This is a cross-sectional view showing another example of the lens shape. Figure 14 This is a top view showing another example of the shape of the upper surface of a lens. Figure 15 This is a cross-sectional view showing an example of the structure of a CMOS image sensor, which is a second embodiment of a camera device to which this technology is applied. Figure 16 This is a diagram illustrating the third step of the manufacturing method according to the second embodiment. Figure 17 This is a diagram illustrating the fourth step of the manufacturing method according to the second embodiment. Figure 18 This is a block diagram illustrating an example of the construction of a digital camera as an electronic device applying this technology. Figure 19 This is a block diagram illustrating a schematic example of the construction of a vehicle control system. Figure 20 This is an explanatory diagram showing an example of the camera unit's mounting location. Detailed Implementation

[0012] The following will describe a mode for implementing this technology (hereinafter referred to as an embodiment). Note that the description will be given in the following order. 1. First embodiment (CMOS image sensor including lens and protective film) 2. Second embodiment (CMOS image sensor including a resin film between the lens and the protective film) 3. Examples of applications of electronic devices 4. Examples of applications of moving bodies

[0013] Note that in the accompanying drawings referenced in the following description, identical or similar parts are indicated by identical or similar reference numerals, and redundant descriptions are omitted where appropriate. However, the drawings are schematic, and the relationships between thicknesses and planar dimensions, the proportions of each layer thickness, etc., differ from reality. Furthermore, the drawings may include parts with different dimensional relationships or scales between figures.

[0014] Furthermore, the definitions of directions such as up and down in the following description are given for ease of explanation only and do not limit the technical concept of this disclosure. For example, when observing the target with a 90° rotation, up and down are converted and interpreted as left and right, and when observing the target with a 180° rotation, up and down are interpreted as reversed.

[0015] 1. First Embodiment Example of circuit construction for a CMOS image sensor Figure 1This is a diagram illustrating an example of the circuit construction of a complementary metal oxide semiconductor (CMOS) image sensor, which is a first embodiment of a camera device applying this technology.

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

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

[0018] The pixel array 11 is formed by arranging pixels 100 in a two-dimensional shape (matrix shape), these pixels 100 being multi-photoelectric conversion element pixels. Each pixel 100 includes two photoelectric conversion elements, such as photodiodes, and converts incident light into electrical charge on a per-photoelectric conversion element basis. Each pixel 100 also includes a pixel circuit that generates an electrical signal based on the charge converted by each photoelectric conversion element and outputs the electrical signal to the vertical signal line 22, which will be described later.

[0019] In the pixel array section 11, a pixel driving line 21 for transmitting control signals of the pixel circuit is arranged for each row of pixels 100, and the same pixel driving line 21 is connected to the same row of pixels 100. In the pixel array section 11, a vertical signal line 22 for transmitting electrical signals generated by the pixel circuit is arranged for each column of pixels 100, and the same vertical signal line 22 is connected to the same column of pixels 100.

[0020] For example, the vertical drive circuit 12 is formed by a shift register. The vertical drive circuit 12 sequentially selects pixel drive lines 21 and provides drive signals to the selected pixel drive lines 21 for driving the pixel circuits. Therefore, the pixel circuits of the pixel 100, which are provided with drive signals via the pixel drive lines 21, generate electrical signals in units of photoelectric conversion elements and output the electrical signals to the vertical signal line 22.

[0021] The column signal processing circuit 13 includes circuitry for each column of pixels 100. Each circuit is connected to each vertical signal line 22 and performs predetermined signal processing on the electrical signals provided via the vertical signal line 22 on a per-photoelectric conversion element basis. Examples of signal processing include correlated double sampling and analog-to-digital (AD) conversion for removing fixed-pattern noise inherent in the pixels.

[0022] For example, the horizontal drive circuit 14 is formed by a shift register. The horizontal drive circuit 14 sequentially selects each circuit of the column signal processing circuit 13 and provides a horizontal scan signal to the selected circuit. Therefore, each circuit of the column signal processing circuit 13 outputs the electrical signal obtained after signal processing to the 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 electrical signals. Examples of processing include buffering, black level adjustment, column difference correction, and various digital signal processing. The electrical signals output from the output circuit 15, on a per-photoelectric conversion element basis, are used for phase difference detection or image generation.

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

[0025] Input / output terminal 17 exchanges signals with external devices.

[0026] Example of pixel array construction Figure 2 This is a cross-sectional view parallel to the imaging surface of the semiconductor substrate on which the CMOS image sensor 10 is formed, and shows... Figure 1 Example of the construction of pixel array section 11.

[0027] exist Figure 2 In the example shown, 4×4 (4 rows and 4 columns) pixels 100 among the multiple pixels 100 arranged in two dimensions in the pixel array section 11 are shown as a representative example.

[0028] Figure 2 The arrangement of pixels 100 is a Bayer arrangement. Specifically, for each 2×2 pixels 100, the colors of the color filters formed on the top left pixel 100, top right pixel 100, bottom left pixel 100, and bottom right pixel 100 are red (R), green (G), green (G), and blue (B), respectively.

[0029] Pixel 100 has two photoelectric conversion elements 112a and 112b, which are physically separated in the semiconductor substrate by impurities 111 formed along the column direction. Note that in the following description, when it is not necessary to distinguish between photoelectric conversion elements 112 and 112b, they are collectively referred to as photoelectric conversion element 112. The photoelectric conversion element 112b of one pixel in two adjacent pixels 100 and the photoelectric conversion element 112a of the other pixel in those two pixels are physically separated from each other in the semiconductor substrate by inter-pixel separation portions 115 arranged in a lattice shape. The inter-pixel separation portions 115 are formed of an oxide film or a metal, etc.

[0030] In each pixel 100, a portion of the inter-pixel separation portion 115 is formed as a protrusion toward the center of the pixel 100. In the following description, the protruding portion is referred to as the protrusion portion 115P. The protrusion portion 115P can improve the accuracy of phase difference detection while suppressing the decrease in sensitivity and the increase in the occurrence of color mixing. For example, the details of the protrusion portion 115P are described in JP 2018-201015 A.

[0031] Note that in Figure 2 In the example shown, protrusion 115P is formed in all pixels 100, but protrusion 115P may also be formed only in pixels 100 that include a color filter of a predetermined color. The arrangement of pixels 100 may be different from the Bayer arrangement.

[0032] Example of CMOS image sensor structure Figure 3 It is a cross-sectional view of the imaging plane perpendicular to the semiconductor substrate, and shows... Figure 1 Example of the structure of the CMOS image sensor 10.

[0033] exist Figure 3 For the sake of simplicity, only two pixels 100 at the center (optical axis center) of the CMOS image sensor 10 and a portion of two pixels 100 adjacent to these two central pixels 100 on the side away from the center are shown.

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

[0035] For example, the semiconductor substrate 130 is formed of a silicon substrate. A pixel array portion 11 is formed on the semiconductor substrate 130. Specifically, pixels 100, each including photoelectric conversion elements 112a and 112b, and pixel circuits (not shown) are formed in a matrix shape on the semiconductor substrate 130. A pixel separation portion 115 is formed between the photoelectric conversion elements 112b of one pixel 100 and the photoelectric conversion element 112a of the other pixel 100 in two adjacent pixels 100. A protrusion 115P is formed between the photoelectric conversion elements 112a and 112b in the same pixel 100.

[0036] Wiring layer 131 includes wiring such as pixel drive lines 21, vertical signal lines 22, and power lines Vdd. Wiring layer 131 and pixel circuitry are interconnected via via plugs. Wiring layer 131 is formed of multiple layers, and these layers are interconnected via via plugs. For example, the wiring in wiring layer 131 can be formed of a metal such as Al or Cu. For example, the via plugs can be formed of a metal such as W or Cu. Insulation of wiring layer 131 can be provided using materials such as SiO2.

[0037] An insulating film 132 made of SiO, SiON, or SiN is formed on a semiconductor substrate 130. A color filter layer 133 is formed on the insulating film 132. In the color filter layer 133, a color filter 151 is formed for each photoelectric conversion element 112, selectively transmitting light of a predetermined color. The color filters 151 of photoelectric conversion elements 112a and 112b included in the same pixel 100 have the same color. A pixel partition 152 formed by a void section is formed between adjacent color filters 151, and the refractive index of the void section is lower than that of the color filter 151.

[0038] A protective film 134 (blocking film) is formed on the color filter 133 layer. The material of the protective film 134 can be SiO, SiON, or SiN, and it is desirable that the refractive index is close to that of the color filter 151. The optical path length of the thickness of the protective film 134 is desirable to be half the wavelength of the incident light. When the optical path length of the thickness of the protective film 134 is half the wavelength of the incident light, and the incident light is visible light with a wavelength between 400 nm and 700 nm, the optical path length of 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 with 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] Lens layer 136 is formed on etch stop film 135. Within lens layer 136, a lens 161 is formed for each photoelectric conversion element 112, the lens 161 having an upper surface 161a and a lower surface 161b of identical shape. Figure 3 In the example, lens 161 has a rectangular cross-sectional shape. Examples of materials for lens 161 include SiO, SiON, SiN, and resin materials.

[0041] The optical path length of the thickness of lens 161 is preferably one-quarter of the wavelength of the incident light. When the optical path length of the thickness of lens 161 is one-quarter of the wavelength of the incident light, and the incident light is visible light with a wavelength between 400 nm and 700 nm, the optical path length of 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 the material of lens 161 is 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] Example of the shape of the upper surface of the lens Figure 4 The image includes a top view of the CMOS image sensor 10 and shows the shape of the upper surface 161a of the lens 161.

[0043] exist Figure 4 In the example shown, a 2×2 lens 161 formed in a portion of the plurality of lenses 161 formed for each photoelectric conversion element 112 in the CMOS image sensor 10 is shown as a representative example.

[0044] exist Figure 4 In example A, the upper surface 161a of lens 161 has a rectangular shape. Figure 4 In example B, the upper surface 161a of lens 161 is circular in shape. Figure 4 In example C, the upper surface 161a of lens 161 is octagonal in shape. Although not shown in the figure, the upper surface 161a and the lower surface 161b have the same shape. The shapes of the upper surface 161a and the lower surface 161b of lens 161 are not limited to... Figure 4 The shapes shown in A through C can be any shape other than a polygon, such as a rectangle or an octagon.

[0045] Description of manufacturing method Figures 5 to 10 This is a diagram illustrating the manufacturing method of the color filter layer 133, the protective film 134, the etch stop film 135, and the lens 161.

[0046] Figure 5 A and Figure 6 A is a top view of the area of ​​2×2 photoelectric conversion elements 112 located at the center of the 2×2 pixels 100 of the CMOS image sensor 10 and adjacent to each other, as viewed from above. Figure 5 B Figure 6 B and Figures 7 to 10 This is a cross-sectional view of the region extending from the center of the CMOS image sensor 10 to its outer periphery. Figure 5 B Figure 6 B and Figures 7 to 10 In the middle, the left side is the central side, and the right side is the peripheral area side.

[0047] like Figure 5 As shown in A and B, in the first step, a color filter layer 133 is formed on the imaging surface of the semiconductor substrate 130 (located on the opposite side of the wiring layer 131 formed on the semiconductor substrate 130) by wet etching for temporary wall removal. Therefore, a SiO layer 201 is formed on the color filter layer 133. For example, the thickness of the SiO layer 201 is 60 nm.

[0048] Note that the CMOS image sensor 10 has pupil correction functionality. Therefore, as... Figure 5 As shown in Figure B, as the distance from the center of the CMOS image sensor 10 increases, the horizontal position of the color filter 151 shifts relative to the horizontal position of the photoelectric conversion element 112 corresponding to the color filter 151. Figure 5 In A, the color filter 151 is shown in perspective.

[0049] In the second step, such as Figure 6 As shown in A and B, for example, a protective film 134 is formed on the color filter layer 133 by chemical vapor deposition (CVD) of 100 nm tetraethoxysilane. Thus, for example, a 130 nm SiO film is formed on the color filter layer 133 as the protective film 134.

[0050] In the third step, such as Figure 7As shown, an etch stop film 135 is formed on the protective film 134. In the fourth step, as... Figure 8 As shown, a lens film 202 formed of the material of lens 161 is formed on the etching stop film 135. For example, the lens film 202 is an LTO (SiO) film.

[0051] In the fifth step, such as Figure 9 As shown, resist 203 is applied to the area on the lens film 202 where the lens 161 will be formed by photolithography. As described above, the CMOS image sensor 10 has a pupil correction function. Therefore, as... Figure 9 As shown, as the distance from the center of the CMOS image sensor 10 increases, the position of the resist 203 corresponding to the lens 161 in the horizontal direction shifts relative to the position of the photoelectric conversion element 112 corresponding to the lens 161 in the horizontal direction.

[0052] In the sixth step, the lens film 202 in the areas where the resist 203 was not formed is removed by dry etching. At this time, since the etch stop film 135 is formed beneath the lens film 202, the dry etching is stopped by the etch stop film 135. After dry etching, the resist 203 is removed, thereby forming... Figure 10 Lens 161 is shown.

[0053] Details of the etching stop film Figure 11 yes Figure 10 An enlarged view of rectangle S in the image is provided to illustrate the details of the etch stop film 135.

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

[0055] Other examples of pixel wall structures Figure 12 Cross-sectional views are included, showing other structural examples of the pixel partition 152.

[0056] Note that in Figure 12 In, with Figure 2 The corresponding parts are given the same reference numerals.

[0057] exist Figure 12 In example A, the pixel wall portion 152 is formed by a gap portion 231 and a blocking metal layer 232 formed on the semiconductor substrate 130 side of the pixel wall portion 152.

[0058] exist Figure 12 In example B, the pixel wall portion 152 is formed by a low refractive index layer 241 and a barrier metal layer 242 formed on the semiconductor substrate 130 side of the pixel wall portion 152. The low refractive index layer 241 is made of a material with a refractive index lower than that of the color filter 151. Examples of materials for the barrier metal layers 232 and 242 include Ti and TiN.

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

[0060] Another example of the cross-sectional shape of a lens Figure 13 This is a cross-sectional view showing an example of the cross-sectional shape of lens 161.

[0061] exist Figure 13 In, with Figure 3 The corresponding parts are given the same reference numerals.

[0062] exist Figure 13 In the example, the upper surface of the color filter layer 133 is not flat. Therefore, the shape of the upper surface of the protective film 134 formed on the color filter layer 133 and the shape of the upper surface of the etch stop film 135 formed on the protective film 134 are also 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 lower surface 161b of the lens 161 are the same. Although not shown, the corners of the lens 161 can be rounded.

[0063] Another example of the shape of the upper surface of a lens Figure 14 This is a top view of the CMOS image sensor 10, and shows another example of the shape of the upper surface 161a of the lens 161.

[0064] exist Figure 14 In, with Figure 4 Corresponding parts are given the same reference numerals. Figure 14 In the example shown, a 4×4 lens 161 formed in a portion of the plurality of lenses 161 formed for each photoelectric conversion element 112 in the CMOS image sensor 10 is shown as a representative example.

[0065] exist Figure 14In the example, the upper surface 161a of the 4×4 lenses 161 are all rectangular in shape, but their sizes are different. Specifically, among the 4×4 lenses 161, the upper surface 161a of the 2×2 lenses 161 at the upper left and lower right corners is larger than the upper surface 161a of the 2×2 lenses 161 at the upper right and lower left corners.

[0066] Although not shown, the size of the lens 161 and the spacing between adjacent lenses 161 can 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 pixels 100, serving as multiple photoelectric conversion elements, are arranged in a two-dimensional manner. A color filter 151 is formed on the semiconductor substrate 130 for each photoelectric conversion element 112, and a lens 161 is formed on the color filter 151 for each photoelectric conversion element 112. Therefore, light focused by the lens 161 enters the pixel 100.

[0068] Therefore, in the CMOS image sensor 10, which includes pixels 100 as multiple photoelectric conversion elements, sensitivity can be improved and color mixing can be reduced simultaneously. Furthermore, compared to a CMOS image sensor including an on-chip lens that is taller and has a greater curvature than lens 161, the separation ratio of electrical signals corresponding to photoelectric conversion elements 112a and 112b at higher image heights can be improved. Moreover, compared to a CMOS image sensor including an on-chip lens and a CMOS image sensor without a lens, the separation ratio of electrical signals corresponding to photoelectric conversion elements 112a and 112b at the center of the image height can be improved.

[0069] In the CMOS image sensor 10, a protective film 134 is formed between the color filter 151 and the lens 161. Therefore, it is possible to prevent the degradation of spectral characteristics due to material decomposition of the color filter 151 and improve 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. In addition, the reliability of the CMOS image sensor 10 can be improved.

[0071] 2. Second Embodiment Example of CMOS image sensor structure Figure 15This is a cross-sectional view of the imaging surface perpendicular to the semiconductor substrate, and shows a structural example of a CMOS image sensor according to a second embodiment of an imaging device applying the present technology.

[0072] Note that in Figure 15 For the sake of simplicity, only the two central pixels 100 and a portion of the two adjacent pixels 100 on the side away from the center of the CMOS image sensor 300 are shown.

[0073] exist Figure 15 In the CMOS image sensor 300, with Figure 3 The parts corresponding to the CMOS image sensor 10 in the figure are given the same reference numerals. Therefore, the description of these parts is omitted as appropriate, and the parts that are different from the CMOS image sensor 10 will be described in detail. Figure 15 The difference between the CMOS image sensor 300 and the CMOS image sensor 10 is that a resin layer 301 is formed on the protective film 134, but the other structures are formed in a manner similar to those of 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 Figure 16 and Figure 17 This is a schematic diagram illustrating the manufacturing method of resin layer 301 and etch stop film 135.

[0076] Figure 16 and Figure 17 This is a cross-sectional view of the region from the center to the outer periphery of the CMOS image sensor 300. Figure 16 and Figure 17 In the middle, the left side is the central side, and the right side is the peripheral area side.

[0077] After executing the reference Figure 5 and Figure 6 After explaining the first and second steps, in the third step, as follows: Figure 16 As shown, the protective film 134 is planarized, and a resin material is coated onto the protective film 134 to form a resin layer 301. In the fourth step, as... Figure 17 As shown, an etch stop film 135 is formed on the resin layer 301.

[0078] After the fourth step, perform the above-mentioned reference. Figures 8 to 10 The fourth to sixth steps are described, and a lens layer 136 is formed on the etch stop film 135.

[0079] As described above, similar to the CMOS image sensor 10, the CMOS image sensor 300 includes a semiconductor substrate 130 on which pixels 100 are arranged in two dimensions, a color filter 151, a protective film 134, an etch stop film 135, and a lens 161. Therefore, the same effect as that of the CMOS image sensor 10 can be obtained.

[0080] Note that an etch stop film 135 is not necessarily formed in the CMOS image sensor 300. In this case, the dry etching performed during the formation of the lens 161 stops at the resin layer 301. Therefore, the protective film 134 in the area where the lens 161 is not formed can be prevented from being dry etched.

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

[0082] When the pixel partition 152 includes a protrusion, the color filters 151 of adjacent pixels 100 are separated by the pixel partition 152 arranged in a grid shape. Specifically, the pixel partition 152 is formed between the color filter 151 of one pixel 100 corresponding to the photoelectric conversion element 112b and the color filter 151 of the other pixel 100 corresponding to the photoelectric conversion element 112a. Then, in each pixel 100, a portion of the pixel partition 152 is formed to protrude toward the center of the pixel 100 in a protruding manner. The color filters 151 corresponding to the photoelectric conversion elements 112a and 112b in the same pixel 100 are separated from each other by the protrusion, which is a portion that protrudes in a protruding manner.

[0083] Note that, similar to the protrusion 115P, the protrusion of the pixel partition 152 may be formed only for the pixels 100 that include the color filter 151 of the predetermined color, rather than for all pixels 100.

[0084] 3. Examples of applications of electronic devices For example, the aforementioned CMOS image sensor 10 (300) can be applied to various electronic devices such as digital cameras (e.g., digital still cameras and digital video cameras) and mobile phones with camera functions.

[0085] Figure 18 This is a block diagram illustrating an example of the construction of a digital camera as an electronic device applying this technology.

[0086] like Figure 18As shown, the digital camera 1001 includes an optical system 1002, a shutter device 1003, a solid-state imaging element 1004, a control circuit 1005, a signal processing circuit 1006, a monitor 1007, and a memory 1008, and can capture still images and moving images.

[0087] The optical system 1002 includes one or more lenses that guide light (incident light) from the subject to the solid-state imaging element 1004 and form an image on the light-receiving surface of the solid-state imaging element 1004.

[0088] The shutter device 1003 is arranged between the optical system 1002 and the solid-state imaging element 1004, and under the control of the control circuit 1005, it controls the illumination period and the shading period of the solid-state imaging element 1004.

[0089] The solid-state imaging element 1004 is formed from the aforementioned CMOS image sensor 10 (300). The solid-state imaging element 1004 accumulates signal charge within a specific period based on the light that forms an image on the light-receiving surface via the optical system 1002 and the shutter device 1003. The accumulated signal charge in the solid-state imaging element 1004 is transmitted according to a drive signal (timing signal) provided from the control circuit 1005.

[0090] The control circuit 1005 outputs drive signals for controlling the transmission operation of the solid-state imaging element 1004 and the shutter operation of the shutter device 1003, and drives the solid-state imaging element 1004 and the shutter device 1003.

[0091] The signal processing circuit 1006 performs various signal processing on the signal charge output from the solid-state imaging element 1004. The image (image data) obtained after the signal processing is performed by the signal processing circuit 1006 is provided to the monitor 1007 and displayed on the monitor 1007, or provided to the memory 1008 and stored (recorded) in the memory 1008.

[0092] In the digital camera 1001 formed as described above, a CMOS image sensor 10 (300) is used as a solid-state imaging element 1004, thereby achieving the aforementioned effects. Specifically, for example, in a solid-state imaging element 1004 that includes multiple photoelectric conversion element pixels, sensitivity can be improved and color mixing can be reduced simultaneously.

[0093] 4. Examples of applications of moving bodies The technology disclosed herein (the Technology) can be applied to a variety of products. For example, the Technology disclosed herein can be implemented as a device mounted on any type of mobile body, such as automobiles, electric vehicles, hybrid vehicles, motorcycles, bicycles, personal motor vehicles, airplanes, unmanned aerial vehicles, ships, and robots.

[0094] Figure 19 This is a block diagram illustrating an example of a schematic construction of a vehicle control system, which is an example of a mobile body control system to which the technology according to embodiments of this disclosure can be applied.

[0095] The vehicle control system 12000 includes multiple electronic control units interconnected via a communication network 12001. Figure 19 In the example shown, the vehicle control system 12000 includes a drive system control unit 12010, a body system control unit 12020, an external information detection unit 12030, an internal information detection unit 12040, and an integrated control unit 12050. Furthermore, a microcomputer 12051, an audio / image output unit 12052, and an in-vehicle network interface (I / F) 12053 are shown as functional components of the integrated control unit 12050.

[0096] The drive system control unit 12010 controls the operation of devices related to the vehicle's drive system according to various programs. For example, the drive system control unit 12010 acts as a control device for devices such as: a drive force generating device (e.g., an internal combustion engine, drive motor, etc.) for generating vehicle driving force, a drive force transmission mechanism for transmitting driving force to the wheels, a steering mechanism for adjusting the vehicle's steering angle, and a braking device for generating vehicle braking force.

[0097] The body system control unit 12020 controls the operation of various devices installed on the vehicle body according to various programs. For example, the body system control unit 12020 acts as a control device for devices such as keyless entry systems, smart key systems, power windows, or various lights such as headlights, reversing lights, brake lights, turn signals, or fog lights. In this case, radio waves or signals from various switches transmitted from a portable device that serves as a key alternative can be input to the body system control unit 12020. The body system control unit 12020 receives these input radio waves or signals and controls the vehicle's door locking devices, power windows, or lights, etc.

[0098] The exterior information detection unit 12030 detects information about the exterior of the vehicle, including the vehicle control system 12000. For example, the exterior information detection unit 12030 is connected to the camera unit 12031. The exterior information detection unit 12030 causes the camera unit 12031 to capture images of the exterior of the vehicle and receives the captured images. Based on the received images, the exterior information detection unit 12030 can perform processing for detecting objects such as people, vehicles, obstacles, signs, or characters on the road surface, or processing for detecting their distance.

[0099] The camera unit 12031 is an optical sensor that receives light and outputs an electrical signal corresponding to the amount of light received. The camera unit 12031 may also output an electrical signal as an image, or an electrical signal as distance measurement information. Furthermore, the light received by the camera unit 12031 can be visible light, or it may be invisible light such as infrared light.

[0100] The in-vehicle information detection unit 12040 detects information about the interior of the vehicle. For example, the in-vehicle information detection unit 12040 is connected to a driver state detection unit 12041 for detecting the driver's state. The driver state detection unit 12041 includes, for example, a camera for capturing images of the driver. Based on the detection information input from the driver state detection unit 12041, the in-vehicle information detection unit 12040 can calculate the driver's fatigue level or the driver's concentration level, or determine whether the driver is dozing off.

[0101] The microcomputer 12051 can calculate target control values ​​for the drive force generating device, steering mechanism, or braking device based on information about the vehicle's interior and exterior obtained by the external information detection unit 12030 or the internal information detection unit 12040, and output control commands to the drive system control unit 12010. For example, the microcomputer 12051 can perform coordinated control to realize functions of advanced driver assistance systems (ADAS), including collision avoidance or shock absorption, following distance-based driving, speed maintenance driving, collision warning, or lane departure warning.

[0102] In addition, based on the environmental information about the vehicle obtained by the external information detection unit 12030 or the internal information detection unit 12040, the microcomputer 12051 can perform coordinated control for autonomous driving by controlling the drive force generating device, steering mechanism or braking device, etc., which enables the vehicle to drive automatically without relying on the driver's operation.

[0103] Furthermore, the microcomputer 12051 can output control commands to the body system control unit 12020 based on information about the vehicle's exterior obtained by the exterior information detection unit 12030. For example, the microcomputer 12051 can perform coordinated control aimed at preventing glare by controlling the headlights to switch from high beams to low beams, for example, based on the position of the vehicle ahead or oncoming vehicle detected by the exterior information detection unit 12030.

[0104] The sound / image output unit 12052 transmits an output signal of at least one of sound and image to an output device capable of visually or audibly notifying vehicle occupants or the outside of the vehicle. Figure 19In the example, audio speaker 12061, display unit 12062, and instrument panel 12063 are shown as output devices. Display unit 12062 may include, for example, at least one of a vehicle display and a head-up display.

[0105] Figure 20 This is a diagram showing an example of the mounting position of the camera unit 12031.

[0106] exist Figure 20 In the middle, the camera unit 12031 includes camera units 12101, 12102, 12103, 12104 and 12105.

[0107] Cameras 12101, 12102, 12103, 12104, and 12105 are installed in locations such as the front nose, rearview mirrors, rear bumper, rear door, and upper part of the interior windshield of vehicle 12100. Camera 12101 at the front nose and camera 12105 at the upper part of the interior windshield primarily acquire images of the front of vehicle 12100. Cameras 12102 and 12103 at the rearview mirrors primarily acquire images of the sides of vehicle 12100. Camera 12104 at the rear bumper or rear door primarily acquires images of the rear of vehicle 12100. Camera 12105 at the upper part of the interior windshield is primarily used to detect vehicles, pedestrians, obstacles, traffic lights, traffic signs, or lanes ahead.

[0108] Notice, Figure 20 Examples of the camera ranges of camera units 12101 to 12104 are shown. Camera range 12111 represents the camera range of camera unit 12101 located at the front nose. Camera ranges 12112 and 12113 represent the camera ranges of camera units 12102 and 12103 located at the rearview mirrors, respectively. Camera range 12114 represents the camera range of camera unit 12104 located at the rear bumper or rear door. For example, a bird's-eye view image of vehicle 12100 is obtained by overlaying image data captured by camera units 12101 to 12104.

[0109] At least one of the camera units 12101 to 12104 may have the function of obtaining distance information. For example, at least one of the camera units 12101 to 12104 may be a stereo camera composed of multiple camera elements, or may be a camera element having pixels for phase difference detection.

[0110] For example, the microcomputer 12051 can determine the distance and time-varying distance (relative speed to the vehicle 12100) of each three-dimensional object within the camera range 12111 to 12114 based on distance information obtained from camera units 12101 to 12104, and extract the nearest three-dimensional object as the preceding vehicle, specifically existing on the driving path of the vehicle 12100 and traveling in approximately the same direction as the vehicle 12100 at a predetermined speed (e.g., equal to or greater than 0 km / h). Furthermore, the microcomputer 12051 can pre-set a following distance to be maintained in front of the preceding vehicle and execute automatic braking control (including follow-stop control), automatic acceleration control (including follow-start control), etc. Therefore, coordinated control for autonomous driving can be performed, enabling the vehicle to drive automatically without relying on driver operation, etc.

[0111] For example, microcomputer 12051 can classify three-dimensional object data of three-dimensional objects into two-wheeled vehicles, standard-sized vehicles, large vehicles, pedestrians, utility poles, and other three-dimensional objects based on distance information obtained from cameras 12101 to 12104, extract the classified three-dimensional object data, and use the extracted three-dimensional object data for automatic obstacle avoidance. For example, microcomputer 12051 identifies obstacles around vehicle 12100 as obstacles that can be visually recognized by the driver of vehicle 12100 and obstacles that are difficult to visually recognize by the driver of vehicle 12100. Then, microcomputer 12051 determines the collision risk to indicate the risk of collision with each obstacle. If the collision risk is equal to or higher than a set value and therefore there is a possibility of collision, microcomputer 12051 outputs a warning to the driver through audio speaker 12061 or display unit 12062, and executes forced deceleration or evasive steering through driving system control unit 12010. Microcomputer 12051 can thus assist driving to avoid collisions.

[0112] At least one of the camera units 12101 to 12104 can be an infrared camera that detects infrared light. For example, the microcomputer 12051 can identify a pedestrian by determining whether a pedestrian exists in the images captured by the camera units 12101 to 12104. This pedestrian identification is performed, for example, by extracting feature points from the images captured by the camera units 12101 to 12104, which are infrared cameras; and by performing pattern matching processing on a series of feature points representing the outline of an object to determine whether it is a pedestrian. When the microcomputer 12051 determines that a pedestrian exists in the images captured by the camera units 12101 to 12104 and thus identifies the pedestrian, the sound / image output unit 12052 controls the display unit 12062 to overlay a square outline for emphasis on the identified pedestrian. In addition, the sound / image output unit 12052 can control the display unit 12062 to display icons or the like for indicating pedestrians at a desired location.

[0113] Examples of vehicle control systems to which the technology according to this disclosure can be applied have been described above. The technology according to this disclosure can be applied to the camera unit 12031 in the above-described configuration. Specifically, a CMOS image sensor 10 (300) can be applied to the camera unit 12031. By applying the technology according to this disclosure to the camera unit 12031, sensitivity can be simultaneously improved and color mixing reduced in the camera unit 12031, which includes pixels with multiple photoelectric conversion elements. This results in more easily viewable captured images, thereby reducing driver fatigue.

[0114] The embodiments of this technology are not limited to the above embodiments, and various modifications can be made without departing from the spirit of this technology.

[0115] For example, a combination of all or part of the above embodiments can be used.

[0116] The effects described in this specification are merely illustrative and are not limited thereto; other effects besides those described in this specification may also be provided.

[0117] This technology can be constructed in the following ways. (1) A camera device, comprising: A semiconductor substrate having pixels arranged in a two-dimensional pattern thereon, each pixel including multiple photoelectric conversion elements; Color filters are formed on the semiconductor substrate in a manner that corresponds to the photoelectric conversion elements respectively; A protective film is formed on the color filter; and A lens, formed on the protective film for each of the photoelectric conversion elements, wherein the upper and lower surfaces of the lens have the same shape, A portion of at least one of the inter-pixel separation portion formed between the photoelectric conversion elements of the adjacent pixels and the inter-pixel wall portion formed between the color filters protrudes in a protruding manner toward the center of each pixel, forming a protrusion. (2) The camera device according to (1) above, wherein, The lens has a rectangular cross-sectional shape. (3) The camera device according to (1) or (2) above, wherein, The optical path length of the thickness of the protective film is half the wavelength of the incident light. (4) The camera device according to any one of (1) to (3) above, wherein, The optical path length of the lens thickness is one-quarter of the wavelength of the incident light. (5) The camera device according to any one of (1) to (4) above, wherein, The optical path length of the protective film is greater than 200 nm and less than 350 nm. (6) The camera device according to any one of (1) to (5) above, wherein, The optical path length of the lens thickness is greater than 100 nm and less than 175 nm. (7) The camera device according to any one of (1) to (6) above, wherein, Each of the color filters is formed to be thicker than the lens. (8) The camera device according to any one of (1) to (7) above, wherein, The pixel partition is formed of a void, a material with a refractive index lower than that of each color filter, or SiO or W. (9) The camera device according to any one of (1) to (7) above, wherein, The pixel wall portion is formed by a void portion or a material with a refractive index lower than that of each color filter, and a barrier metal layer formed on the semiconductor substrate side of the pixel wall portion. (10) The camera device according to any one of (1) to (9) above further includes: An etch stop film is formed between the lens and the protective film. (11) The camera device according to any one of (1) to (10) above further includes: A resin layer is formed between the protective film and the lens. (12) A method for manufacturing a camera device, the method comprising: A protective film is formed on a color filter formed on a semiconductor substrate, on which pixels are arranged in a two-dimensional manner. Each pixel includes multiple photoelectric conversion elements, and the color filter is formed in such a way that it corresponds to each of the photoelectric conversion elements. A lens is formed on the protective film for each of the photoelectric conversion elements, wherein the upper and lower surfaces of the lens have the same shape. A portion of at least one of the inter-pixel separation portion formed between the photoelectric conversion elements of the adjacent pixels and the inter-pixel wall portion formed between the color filters protrudes in a protruding manner toward the center of each pixel, forming a protrusion. (13) An electronic device equipped with a camera, the camera comprising: A semiconductor substrate having pixels arranged in a two-dimensional pattern thereon, each pixel including multiple photoelectric conversion elements; Color filters are formed on the semiconductor substrate in a manner that corresponds to the photoelectric conversion elements respectively; A protective film is formed on the color filter; and A lens, formed on the protective film for each of the photoelectric conversion elements, wherein the upper and lower surfaces of the lens have the same shape, A portion of at least one of the inter-pixel separation portion formed between the photoelectric conversion elements of the adjacent pixels and the inter-pixel wall portion formed between the color filters protrudes in a protruding manner toward the center of each pixel, forming a protrusion. List of reference numerals

[0118] 10: CMOS image sensor; 112a, 112b: photoelectric conversion element; 115: pixel separation part; 115P: protrusion; 130: semiconductor substrate; 134: protective film; 135: etch stop film; 136: lens; 151: color filter; 152: pixel wall part; 231: gap; 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. A camera device, comprising: A semiconductor substrate having pixels arranged in a two-dimensional pattern thereon, each pixel including multiple photoelectric conversion elements; Color filters are formed on the semiconductor substrate in a manner that corresponds to the photoelectric conversion elements respectively; A protective film is formed on the color filter; and A lens, formed on the protective film for each of the photoelectric conversion elements, wherein the upper and lower surfaces of the lens have the same shape, A portion of at least one of the inter-pixel separation portion formed between the photoelectric conversion elements of the adjacent pixels and the inter-pixel wall portion formed between the color filters protrudes in a protruding manner toward the center of each pixel, forming a protrusion.

2. The camera device according to claim 1, wherein, The lens has a rectangular cross-sectional shape.

3. The camera device according to claim 1, wherein, The optical path length of the thickness of the protective film is half the wavelength of the incident light.

4. The camera device according to claim 1, wherein, The optical path length of the lens thickness is one-quarter of the wavelength of the incident light.

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

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

7. The camera device according to claim 1, wherein, Each of the color filters is formed to be thicker than the lens.

8. The camera device according to claim 1, wherein, The pixel partition is formed of a void, a material with a refractive index lower than that of each color filter, or SiO or W.

9. The camera device according to claim 1, wherein, The pixel wall portion is formed by a void portion or a material with a refractive index lower than that of each color filter, and a barrier metal layer formed on the semiconductor substrate side of the pixel wall portion.

10. The camera device according to claim 1, further comprising: An etch stop film is formed between the lens and the protective film.

11. The camera device according to claim 1, further comprising: A resin layer is formed between the protective film and the lens.

12. A method for manufacturing a camera device, the method comprising: A protective film is formed on a color filter formed on a semiconductor substrate, on which pixels are arranged in a two-dimensional manner. Each pixel includes multiple photoelectric conversion elements, and the color filter is formed in such a way that it corresponds to each of the photoelectric conversion elements. A lens is formed on the protective film for each of the photoelectric conversion elements, wherein the upper and lower surfaces of the lens have the same shape. A portion of at least one of the inter-pixel separation portion formed between the photoelectric conversion elements of the adjacent pixels and the inter-pixel wall portion formed between the color filters protrudes in a protruding manner toward the center of each pixel, forming a protrusion.

13. An electronic device equipped with a camera, the camera comprising: A semiconductor substrate having pixels arranged in a two-dimensional pattern thereon, each pixel including multiple photoelectric conversion elements; Color filters are formed on the semiconductor substrate in a manner that corresponds to the photoelectric conversion elements respectively; A protective film is formed on the color filter; and A lens, formed on the protective film for each of the photoelectric conversion elements, wherein the upper and lower surfaces of the lens have the same shape, A portion of at least one of the inter-pixel separation portion formed between the photoelectric conversion elements of the adjacent pixels and the inter-pixel wall portion formed between the color filters protrudes in a protruding manner toward the center of each pixel, forming a protrusion.

Images