Solid-state imaging element, manufacturing method, and electronic apparatus

Abstract

The present disclosure pertains to a solid-state imaging element, a manufacturing method, and an electronic device that make it possible to further improve image quality. The solid-state imaging element includes: a color filter provided on a light-irradiated rear surface side of a semiconductor substrate for each pixel via an insulating layer; a waveguide disposed between adjacent color filters and formed of a low refractive index material having a lower refractive index than the color filters; and a metal layer disposed on the semiconductor substrate side of the waveguide, the metal layer being disposed in the insulating layer closer to the semiconductor substrate side than the semiconductor substrate side surface of the color filter. The metal layer is configured in a shape in which a width of a lower portion closer to the semiconductor substrate side is narrower than a width of an upper portion closer to the waveguide side. The present technology can be applied, for example, to a backside illuminated CMOS image sensor.

Description

Technical Field

[0001] This disclosure relates to solid-state imaging elements, manufacturing methods, and electronic devices, and particularly to solid-state imaging elements, manufacturing methods, and electronic devices that can further improve image quality. Background Technology

[0002] In related technologies, in solid-state imaging elements such as complementary metal-oxide-semiconductor (CMOS) image sensors, image quality is degraded when color mixing occurs due to light passing through a color filter of a given pixel being incident on the photodiode of an adjacent pixel.

[0003] Therefore, Patent Document 1 proposes a solid-state imaging element having the following structure, wherein a blocking metal with a width narrower than the low-refractive-index wall is disposed below the low-refractive-index wall disposed between color filters, thereby suppressing the occurrence of color mixing between pixels.

[0004] Citation List

[0005] Patent documents

[0006] [Patent Document 1] JP 2023-006303 A Summary of the Invention

[0007] Technical issues

[0008] Compared with the structure disclosed in Patent Document 1 above, there is a need to improve image quality by, for example, suppressing the reduction of pixel sensitivity while suppressing the occurrence of color mixing between pixels.

[0009] This disclosure is made in view of this situation and is intended to further improve image quality.

[0010] Solution to the problem

[0011] A solid-state imaging element according to one aspect of this disclosure includes: color filters disposed on the light-illuminated back side of a semiconductor substrate for each pixel, separated by an insulating layer; a waveguide disposed between adjacent color filters and formed of a low-refractive-index material having a lower refractive index than the color filters; and a metal layer disposed on the semiconductor substrate side of the waveguide, wherein the metal layer is configured such that the lower portion closer to the semiconductor substrate side has a narrower width than the upper portion closer to the waveguide side in the insulating layer than the surface of the color filters on the semiconductor substrate side.

[0012] A method for manufacturing a solid-state imaging element according to one aspect of this disclosure includes: providing color filters disposed on a light-illuminated back side of a semiconductor substrate for each pixel, separated by an insulating layer; providing waveguides disposed between adjacent color filters and formed of a low-refractive-index material with a refractive index lower than that of the color filters; and providing a metal layer disposed on the semiconductor substrate side of the waveguide, wherein the metal layer is configured such that the width of the lower portion closer to the semiconductor substrate side is narrower than the width of the upper portion closer to the waveguide side in the insulating layer than the surface of the color filters on the semiconductor substrate side.

[0013] An electronic device according to one aspect of this disclosure includes a solid-state imaging element comprising: a color filter disposed for each pixel on a light-illuminated back side of a semiconductor substrate, separated by an insulating layer; a waveguide disposed between adjacent color filters and formed of a low-refractive-index material having a lower refractive index than the color filters; and a metal layer disposed on the semiconductor substrate side of the waveguide, wherein the metal layer is configured such that the width of the lower portion closer to the semiconductor substrate side is narrower than the width of the upper portion closer to the waveguide side in the insulating layer than the surface of the color filters on the semiconductor substrate side.

[0014] In one aspect of this disclosure, color filters are disposed for each pixel on the light-illuminated back side of a semiconductor substrate, separated by an insulating layer. Waveguides are disposed between adjacent color filters and are formed of a low-refractive-index material with a refractive index lower than that of the color filters. A metal layer is disposed on the semiconductor substrate side of the waveguides, and in the insulating layer closer to the semiconductor substrate side than the semiconductor substrate side of the color filters, the metal layer is configured such that the width of the lower portion closer to the semiconductor substrate side is narrower than the width of the upper portion closer to the waveguide side. Attached Figure Description

[0015] Figure 1 This is a cross-sectional view showing a configuration example of a first embodiment of an imaging element to which this technology is applicable.

[0016] Figure 2 It is used for explanation Figure 1 A diagram illustrating the manufacturing method of the imaging element in the image.

[0017] Figure 3 It is used for explanation Figure 1 A diagram illustrating the manufacturing method of the imaging element in the image.

[0018] Figure 4 This is a cross-sectional view showing a configuration example of a second embodiment of the imaging element.

[0019] Figure 5 It is used for explanation Figure 4 A diagram illustrating the manufacturing method of the imaging element in the image.

[0020] Figure 6 It is used for explanation Figure 4 A diagram illustrating the manufacturing method of the imaging element in the image.

[0021] Figure 7 This is a cross-sectional view showing a configuration example of a third embodiment of the imaging element.

[0022] Figure 8 It is used for explanation Figure 7 A diagram illustrating the manufacturing method of the imaging element in the image.

[0023] Figure 9 It is used for explanation Figure 7 A diagram illustrating the manufacturing method of the imaging element in the image.

[0024] Figure 10 yes Figure 8 The plan view of the groove shown.

[0025] Figure 11 This is a cross-sectional view showing a first modified example of the imaging element.

[0026] Figure 12 This is a cross-sectional view showing a second modified example of the imaging element.

[0027] Figure 13 This is a cross-sectional view showing a third modified example of the imaging element.

[0028] Figure 14 This is a cross-sectional view showing a fourth modified example of the imaging element.

[0029] Figure 15 This is a cross-sectional view showing the fifth modified example of the imaging element.

[0030] Figure 16 This is a cross-sectional view showing the sixth modified example of the imaging element.

[0031] Figure 17 This is a block diagram illustrating an example of the configuration of an imaging device.

[0032] Figure 18 This is a diagram illustrating an example of the use of an image sensor. Detailed Implementation

[0033] The specific implementation schemes to which this technology applies will be described in detail below with reference to the accompanying drawings.

[0034] First example of an imaging element

[0035] Figure 1 This is a cross-sectional view showing a configuration example of a first embodiment of an imaging element to which this technology is applicable.

[0036] Figure 1 Figure A shows an example of the cross-sectional configuration of two adjacent pixels 12-1 and 12-2 in imaging element 11. Figure 1 The structure of metal layer 32, located between two pixels 12-1 and 12-2 and near metal layer 32, is shown in enlarged view in B.

[0037] like Figure 1 As shown in A, the imaging element 11 is constructed by stacking a semiconductor substrate 21, a high dielectric constant film 22, and an insulating layer 23, and by stacking color filters 24-1 and 24-2 and on-chip lenses 25-1 and 25-2 for pixels 12-1 and 12-2, respectively. Note that when there is no need to distinguish between pixels 12-1 and 12-2, color filters 24-1 and 24-2, and on-chip lenses 25-1 and 25-2, they are simply referred to as pixel 12, color filter 24, and on-chip lens 25, respectively. Furthermore, the imaging element 11 is constructed by providing waveguides 31 and metal layers 32 between pixels 12. For example, the imaging element 11 is a back-illuminated CMOS image sensor, in which the back side of the semiconductor substrate 21 is illuminated.

[0038] The semiconductor substrate 21 is formed from, for example, a single-crystal silicon wafer, and a photodiode is provided for each pixel 12. Furthermore, trenches are formed in the semiconductor substrate 21 that extend between adjacent pixels 12, a high-dielectric-constant film 22 is deposited on the sides of the trenches, and a component isolation structure in which a portion of an insulating layer 23 is embedded is provided inside the trenches. That is, the imaging element 11 is configured to have component isolation structures that provide electrical and optical isolation within the semiconductor substrate 21 between the plurality of pixels 12.

[0039] The high dielectric constant film 22 is formed of an insulator with a relative dielectric constant higher than that of silicon dioxide, such as aluminum oxide or hafnium oxide. The insulating layer 23 is formed of an insulator such as silicon dioxide.

[0040] Color filters 24 transmit light received by each pixel 12. In the example shown, color filter 24-1 transmits red light, and color filter 24-2 transmits green light. On-chip lens 25 collects light for the corresponding pixel 12.

[0041] Waveguide 31 is disposed between adjacent color filters 24. Waveguide 31 is formed of a low-refractive-index material (e.g., n = 1.0~1.5) with a refractive index lower than that of the color filters 24. Due to the refractive index difference between them, light traveling from the side of the color filter 24 of a given pixel 12 toward the adjacent pixel 12 can be totally internally reflected and guided into the given pixel 12. Furthermore, in the cross-sectional view shown, the top and bottom surfaces and both sides of waveguide 31 are surrounded by a thin film of insulating layer 23 to protect waveguide 31. Examples of low-refractive-index materials constituting waveguide 31 include inorganic films such as SiN, SiO2, and SiON, as well as resin-based materials (organic films) such as styrene-based resins, acrylic resins, styrene-acrylic copolymer resins, or siloxane resins.

[0042] Metal layer 32 is disposed below waveguide 31 and closer to semiconductor substrate 21 than color filter 24. Furthermore, in imaging element 11, metal layer 32 has a two-layer structure consisting of metal layer 32-1 and metal layer 32-2. Metal layer 32-1 and metal layer 32-2 are formed of different types of metals. For example, a combination of light-shielding metals such as Ti, TiN, and W can be used.

[0043] like Figure 1 As shown in Figure B, metal layer 32 is configured such that the width d1 of metal layer 32-1 is less than or equal to the width D of waveguide 31 (approximately the same as or narrower than the width D), and metal layer 32-2 is configured such that the width d2 of metal layer 32-2 is narrower than the width d1 of metal layer 32-1. Furthermore, as shown, metal layers 32-1 and 32-2 are disposed in insulating layer 23 on the semiconductor substrate 21 side below color filter 24.

[0044] By providing a metal layer 32 with this configuration below the waveguide 31, light incident along the oblique direction indicated by the hollow arrow can be reflected by the metal layer 32, and color mixing between pixels 12 can be suppressed. Furthermore, by having a narrower shape on the semiconductor substrate 21 side, the metal layer 32 can improve quantum efficiency Qe by reducing light absorption and suppress the decrease in sensitivity of pixel 12.

[0045] In this way, the imaging element 11 suppresses color mixing between pixels 12 and suppresses the reduction in sensitivity of pixels 12, thereby further improving image quality.

[0046] Reference Figure 2 and Figure 3 The manufacturing method of imaging element 11 is explained.

[0047] In the first step, such as Figure 2As shown in the first row, a high dielectric constant film 22 is deposited on the back side of the semiconductor substrate 21, and the high dielectric constant film 22 is deposited on the side of the trench formed between the pixels 12 in the semiconductor substrate 21. In addition, an insulator 23a, which serves as part of the insulating layer 23, is stacked on the back side of the semiconductor substrate 21 through the high dielectric constant film 22 and is embedded in the trench in the semiconductor substrate 21.

[0048] In the second step, such as Figure 2 As shown in the second row, a metal film 41-2 serving as a metal layer 32-2, a metal film 41-1 serving as a metal layer 32-1, and an insulating film 23b serving as part of the insulating layer 23 are deposited on the insulator 23a.

[0049] In the third step, such as Figure 2 As shown in the third row, a waveguide component 42 serving as a waveguide 31 is stacked on the insulating film 23b.

[0050] In the fourth step, waveguide component 42, insulating film 23b, metal film 41-1, and metal film 41-2 are processed by, for example, wet etching. The result is as follows: Figure 3 As shown in the first row, waveguide 31 and metal layer 32 are formed between pixels 12. At this time, by optimizing the type, ratio, and rate of the chemical solution used for wet etching, the metal layer 32 is processed such that the width d2 of metal layer 32-2 is narrower than the width d1 of metal layer 32-1, as shown... Figure 1 As shown in B in the diagram.

[0051] In the fifth step, an insulating film is deposited, stacked on the insulator 23a, surrounding both sides and the top of the waveguide 31, and connected to the insulating film 23b, thereby forming an insulating layer 23 protecting the waveguide 31, as shown below. Figure 3 As shown in the second line of the diagram. Note that the insulating layer 23, which is constructed by depositing insulating films in multiple steps, can be formed from insulating films deposited using different deposition methods in each step.

[0052] In the sixth step, as Figure 3 As shown in the third row, color filters 24-1 and 24-2 are formed, with waveguide 31 positioned between them. Subsequently, on-sheet lens 25 is stacked, thereby creating a structure as shown in the image. Figure 1 The imaging element 11 shown.

[0053] By using the manufacturing method described above, an imaging element 11 that can suppress color mixing between pixels 12 and suppress the decrease in sensitivity of pixels 12 can be manufactured.

[0054] Note that in the imaging element 11, the trenches formed between the pixels 12 in the semiconductor substrate 21 can be formed by excavating from the back side or the front side of the semiconductor substrate 21, and can be formed to penetrate the semiconductor substrate 21.

[0055] Second configuration example of imaging element

[0056] Figure 4 This is a cross-sectional view illustrating a configuration example of a second embodiment of an imaging element to which this technology is applicable. Figure 4 In the imaging element 11A shown, with Figure 1 The same configuration as the imaging element 11 in the figure is indicated by the same reference numerals, and its detailed description will be omitted.

[0057] like Figure 4 As shown, the imaging element 11A comprises a semiconductor substrate 21, a high dielectric constant film 22, an insulating layer 23, a color filter 24, an on-chip lens 25, and a waveguide 31, which are connected to... Figure 1 The imaging element 11 is constructed in the same manner. On the other hand, the metal layer 32A of the imaging element 11A has the same... Figure 1 The metal layer 32 of the imaging element 11 has different configurations.

[0058] Right now, Figure 1 Metal layer 32 has a two-layer structure formed of different types of metals, while metal layer 32A has a single-layer structure formed of a single type of metal, resulting in different widths at the top and bottom. That is, as... Figure 4 As shown in B in the figure, the metal layer 32A is formed in a T-shape in the cross-sectional view, wherein the portion closer to the waveguide 31 used as the upper part is formed with a wide width d1 (below the width D of the waveguide 31), and the portion closer to the semiconductor substrate 21 used as the lower part is formed with a narrow width d2.

[0059] With Figure 1 In a similar manner to the imaging element 11 in the image, the imaging element 11A with this configuration suppresses the occurrence of color mixing between pixels 12 and suppresses the reduction of sensitivity of pixels 12, thereby further improving image quality.

[0060] Reference Figure 5 and Figure 6 The manufacturing method of imaging element 11A is described.

[0061] In step eleven, as Figure 5As shown in the first row, a high dielectric constant film 22 is deposited on the back side of the semiconductor substrate 21, and the high dielectric constant film 22 is deposited on the side of the trench formed between the pixels 12 in the semiconductor substrate 21. In addition, an insulator 23a, which serves as part of the insulating layer 23, is stacked on the back side of the semiconductor substrate 21 through the high dielectric constant film 22 and is embedded in the trench in the semiconductor substrate 21.

[0062] In the twelfth step, as Figure 5 As shown in the second row, a metal film 41A serving as a metal layer 32A and an insulating film 23b serving as part of the insulating layer 23 are deposited on the insulator 23a.

[0063] In the thirteenth step, as Figure 5 As shown in the third row, a waveguide component 42 serving as a waveguide 31 is stacked on the insulating film 23b.

[0064] In the fourteenth step, the waveguide component 42, the insulating film 23b, and the metal film 41A are processed by, for example, wet etching. The result is as follows: Figure 6 As shown in the first row, waveguide 31 and metal layer 32A are formed between pixels 12. At this time, by optimizing the type, ratio, and rate of the chemical solution used for wet etching, metal layer 32A is processed such that the lower width d2 of metal layer 32A is narrower than the upper width d1 of metal layer 32A, as shown in the first row. Figure 4 As shown in B in the diagram.

[0065] In the fifteenth step, an insulating film is deposited, stacked on the insulator 23a, surrounding both sides and the top of the waveguide 31, and connected to the insulating film 23b, thereby forming an insulating layer 23 protecting the waveguide 31, as shown below. Figure 6 As shown in the second line of the document.

[0066] In the sixteenth step, as Figure 6 As shown in the third row, color filters 24-1 and 24-2 are formed, with waveguide 31 positioned between them. Subsequently, on-sheet lens 25 is stacked, thereby creating a structure as shown in the image. Figure 1 The imaging element 11 shown.

[0067] By using the manufacturing method described above, an imaging element 11A can be manufactured that can suppress color mixing between pixels 12 and suppress the decrease in sensitivity of pixels 12.

[0068] Third configuration example of imaging element

[0069] Figure 7 This is a cross-sectional view illustrating a configuration example of a third embodiment of an imaging element to which this technology is applicable. Figure 7 In the imaging element 11B shown, with Figure 1The same configuration as the imaging element 11 in the figure is indicated by the same reference numerals, and its detailed description will be omitted.

[0070] like Figure 7 As shown, the imaging element 11B comprises a semiconductor substrate 21, a high dielectric constant film 22, an insulating layer 23, a color filter 24, an on-chip lens 25, and a waveguide 31, which are connected to... Figure 1 The imaging element 11 is constructed in the same manner. On the other hand, the metal layer 32B of the imaging element 11B has the same... Figure 1 The metal layer 32 of the imaging element 11 has different configurations.

[0071] Right now, Figure 1 Metal layers 32-1 and 32-2 of the metal layer 32 have approximately the same thickness, however, metal layer 32B has a structure in which metal layer 32B-2 is formed to have a greater thickness (length in the depth direction toward the semiconductor substrate 21) than metal layer 32-1. For example, metal layer 32B-2 is formed to reach a depth near the semiconductor substrate 21.

[0072] Imaging element 11B with this configuration can be compared to Figure 1 The imaging element 11 in the image can more effectively suppress color mixing and further improve image quality.

[0073] Reference Figures 8 to 10 The manufacturing method of imaging element 11B is described.

[0074] In step thirty-one, as Figure 8 As shown in the first row, a high dielectric constant film 22 is deposited on the back side of the semiconductor substrate 21, and the high dielectric constant film 22 is deposited on the sidewalls of the trenches formed between the pixels 12 in the semiconductor substrate 21. In addition, an insulator 23a, which serves as part of the insulating layer 23, is stacked on the back side of the semiconductor substrate 21 through the high dielectric constant film 22 and is embedded inside the trenches in the semiconductor substrate 21.

[0075] In step thirty-two, as Figure 8 As shown in the second row, the trench 43 is processed in the insulator 23a between pixels 12. For example, the trench 43 is processed to a depth near the semiconductor substrate 21, depending on the thickness of the metal layer 32B-2. Figure 10 As shown in a planar manner, the groove 43 is formed in the insulator 23a at intervals corresponding to the width of the pixel 12.

[0076] In step thirty-three, as Figure 8As shown in the third row, a metal film 41B-2, serving as a metal layer 32B-2, is deposited on the insulator 23a, and at this time, the metal film 41B-2 is embedded in the trench 43. In addition, a metal film 41-1, serving as a metal layer 32-1, and an insulating film 23b, serving as part of the insulating layer 23, are deposited, and a waveguide member 42, serving as a waveguide 31, is stacked.

[0077] In step thirty-four, waveguide component 42, insulating film 23b, metal film 41-1, and metal film 41B-2 are processed by, for example, wet etching. The result is as follows: Figure 9 As shown in the first row, waveguide 31 and metal layer 32B are formed between pixels 12. At this time, by optimizing the type, ratio, and rate of the chemical solution used for wet etching, metal layer 32B is processed such that the width d2 of metal layer 32B-2 is narrower than the width d1 of metal layer 32-1, as shown... Figure 7 As shown in B in the diagram.

[0078] In step thirty-five, an insulating film is deposited, stacked on the insulator 23a, surrounding both sides and the top of the waveguide 31, and connected to the insulating film 23b, thereby forming an insulating layer 23 protecting the waveguide 31, as shown below. Figure 9 As shown in the second line of the document.

[0079] In step thirty-six, as Figure 9 As shown in the third row, color filters 24-1 and 24-2 are formed, with waveguide 31 positioned between them. Subsequently, on-sheet lens 25 is stacked, thereby creating a structure as shown in the image. Figure 7 The imaging element 11B shown.

[0080] By using the manufacturing method described above, an imaging element 11B that can suppress color mixing between pixels 12 and suppress the decrease in sensitivity of pixels 12 can be manufactured.

[0081] The first to sixth variations of the imaging element

[0082] Reference Figures 11 to 16 Explain the first to sixth variations of the imaging element.

[0083] Figure 11 This is a cross-sectional view showing a configuration example of the imaging element 11C according to the first modified example. Figure 11 In the imaging element 11C shown, with Figure 1 The same configuration as the imaging element 11 in the figure is indicated by the same reference numerals, and its detailed description will be omitted.

[0084] like Figure 11 As shown, the imaging element 11C comprises a semiconductor substrate 21, a high dielectric constant film 22, an insulating layer 23, a color filter 24, an on-chip lens 25, and a waveguide 31, which are connected to... Figure 1The imaging element 11 is constructed in the same manner. On the other hand, the metal layer 32C of the imaging element 11C has the same... Figure 1 The metal layer 32 of the imaging element 11 has different configurations.

[0085] That is, in the imaging element 11C, the metal layer 32C is formed such that the width d2 of the metal layer 32C-2 is narrower than the trench formed in the semiconductor substrate 21, and the metal layer 32C-2 is formed deep enough to be located inside the trench. That is, the metal layer 32C is formed such that the distal end of the metal layer 32C-2 enters into the trench of the semiconductor substrate 21.

[0086] Imaging element 11C with this configuration can be compared to Figure 7 The imaging element 11B in the image can more effectively suppress color mixing and further improve image quality.

[0087] Figure 12 This is a cross-sectional view showing a configuration example of the imaging element 11D according to the second modified example. Figure 12 In the imaging element 11D shown, with Figure 1 The same configuration as the imaging element 11 in the figure is indicated by the same reference numerals, and its detailed description will be omitted.

[0088] like Figure 12 As shown, the imaging element 11D comprises a semiconductor substrate 21, a high dielectric constant film 22, an insulating layer 23, an on-chip lens 25, and a metal layer 32, which are in conjunction with... Figure 1 The imaging element 11 is constructed in the same manner. On the other hand, the color filter 24D and waveguide 31D of the imaging element 11D have the same... Figure 1 The color filter 24 and waveguide 31 of the imaging element 11 have different configurations.

[0089] That is, in the imaging element 11D, the height of the waveguide 31D is formed to be lower than Figure 1 The height of waveguide 31, and the upper parts of color filters 24D-1 and 24D-2 are formed to protrude from both sides toward the space above waveguide 31D. That is, imaging element 11D is formed such that waveguide 31D is shorter than color filters 24D-1 and 24D-2.

[0090] With Figure 1 In a similar manner to the imaging element 11 in the image, the imaging element 11D with this configuration suppresses the occurrence of color mixing between pixels 12 and suppresses the reduction of sensitivity of pixels 12, thereby further improving image quality.

[0091] Figure 13 This is a cross-sectional view showing a configuration example of the imaging element 11E according to the third modified example. Figure 13 In the imaging element 11E shown, with Figure 1 The same configuration as the imaging element 11 in the figure is indicated by the same reference numerals, and its detailed description will be omitted.

[0092] like Figure 13 As shown, the imaging element 11E comprises a semiconductor substrate 21, a high dielectric constant film 22, an insulating layer 23, a color filter 24, an on-chip lens 25, and a waveguide 31, which are connected to... Figure 1 The imaging element 11 is constructed in the same manner. On the other hand, the metal layer 32E of the imaging element 11E has the same... Figure 1 The metal layer 32 of the imaging element 11 has different configurations.

[0093] That is, in the imaging element 11E, the metal layer 32E is formed from a single type of metal, such that the upper and lower parts have different widths, and is configured as a downwardly convex curved shape. Specifically, by forming the upper part as a downwardly concave curved surface and the lower part as a downwardly convex curved surface, the metal layer 32E presents an overall curved shape. The two sides of the metal layer 32E are also formed as inwardly concave curved surfaces.

[0094] like Figure 13 As shown in B, the metal layer 32E with this curved shape is configured such that the width d1 of the upper part of the metal layer 32E is less than the width E of the waveguide 31, and is configured such that the width d2 of the lower part of the metal layer 32E is narrower than the width d1 of the upper part of the metal layer 32E.

[0095] With Figure 1 In a similar manner to the imaging element 11 in the image, the imaging element 11E with this configuration suppresses the occurrence of color mixing between pixels 12 and suppresses the reduction of sensitivity of pixels 12, thereby further improving image quality.

[0096] Figure 14 This is a cross-sectional view showing a configuration example of the imaging element 11F according to the fourth modified example. Figure 14 In the imaging element 11F shown, with Figure 1 The same configuration as the imaging element 11 in the figure is indicated by the same reference numerals, and its detailed description will be omitted.

[0097] like Figure 14 As shown, the imaging element 11F comprises a semiconductor substrate 21, a high dielectric constant film 22, an insulating layer 23, a color filter 24, an on-chip lens 25, and a waveguide 31, which are connected to... Figure 1 The imaging element 11 is constructed in the same manner. On the other hand, the metal layer 32F of the imaging element 11F has the same... Figure 1 The metal layer 32 of the imaging element 11 has different configurations.

[0098] Right now, Figure 1The metal layer 32 is formed such that the width d1 of the metal layer 32-1 is less than the width D of the waveguide 31, while the metal layer 32F is constructed such that the width d1 of the metal layer 32F-1 is narrower than the width D of the waveguide 31, as shown in the figure. Figure 13 As shown in B in the figure. In addition, the width d2 of metal layer 32F-2 is formed to be narrower than the width d1 of metal layer 32F-1.

[0099] With Figure 1 In a similar manner to the imaging element 11 in the image, the imaging element 11F with this configuration suppresses the occurrence of color mixing between pixels 12 and suppresses the reduction of sensitivity of pixels 12, thereby further improving image quality.

[0100] Figure 15 This is a cross-sectional view showing a configuration example of the imaging element 11G according to the fifth modified example. Figure 15 In the imaging element 11G shown, with Figure 1 The same configuration as the imaging element 11 in the figure is indicated by the same reference numerals, and its detailed description will be omitted.

[0101] like Figure 15 As shown, the imaging element 11G comprises a semiconductor substrate 21, a high dielectric constant film 22, an insulating layer 23, a color filter 24, an on-chip lens 25, and a metal layer 32, which are in conjunction with... Figure 1 The imaging element 11 is configured in the same manner. On the other hand, the waveguide 31G of the imaging element 11G has the same... Figure 1 The waveguide 31 of the imaging element 11 has different configurations.

[0102] For example, the imaging element 11G is configured such that the waveguide 31G is hollow, and air is used as the low refractive index material of the waveguide 31G.

[0103] With Figure 1 In a similar manner to the imaging element 11 in the image, the imaging element 11G with this configuration suppresses the occurrence of color mixing between pixels 12 and suppresses the reduction of sensitivity of pixels 12, thereby further improving image quality.

[0104] Figure 16 This is a cross-sectional view showing a configuration example of the imaging element 11H according to the sixth modified example. Figure 16 In the imaging element 11H shown, with Figure 1 The same configuration as the imaging element 11 in the figure is indicated by the same reference numerals, and its detailed description will be omitted.

[0105] like Figure 16 As shown, the imaging element 11H comprises a semiconductor substrate 21, a high dielectric constant film 22, an insulating layer 23, a color filter 24, an on-chip lens 25, and a metal layer 32, which are in conjunction with... Figure 1The imaging element 11 is constructed in the same manner. On the other hand, the waveguide 31H of the imaging element 11H has the same... Figure 1 The waveguide 31 of the imaging element 11 has different configurations.

[0106] For example, the imaging element 11H is configured such that the waveguide 31H is hollow, the top surface of the waveguide 31H is formed into a V-shaped concave shape, and air is used as the low refractive index material of the waveguide 31H. Note that the top surface of the waveguide 31H can be formed into any shape of concave depression other than V-shape.

[0107] With Figure 1 In a similar manner to the imaging element 11 in the image, the imaging element 11H with this configuration suppresses the occurrence of color mixing between pixels 12 and suppresses the reduction of sensitivity of pixels 12, thereby further improving image quality.

[0108] Examples of the composition of electronic devices

[0109] The imaging element 11 described above can be applied to various electronic devices, such as imaging systems like digital still cameras or digital video cameras, mobile phones with imaging capabilities, and other devices with imaging capabilities.

[0110] Figure 17 This is a block diagram illustrating an example of the configuration of an imaging device installed in an electronic device.

[0111] like Figure 17 As shown, the imaging device 101 includes an optical system 102, an imaging element 103, a signal processing circuit 104, a monitor 105, and a memory 106, which can capture still images and moving images.

[0112] The optical system 102 includes one or more lenses that guide image light (incident light) from the subject to the imaging element 103 and form an image on the light receiving surface (sensor unit) of the imaging element 103.

[0113] The imaging element 11 described above is used as the imaging element 103. Electrons accumulate in the imaging element 103 for a certain period of time based on the image formed on the light receiving surface via the optical system 102. Then, a signal corresponding to the electrons accumulated in the imaging element 103 is supplied to the signal processing circuit 104.

[0114] The signal processing circuit 104 performs various types of signal processing on the pixel signals output from the imaging element 103. The image (image data) obtained by the signal processing circuit 104 is supplied to the monitor 105 and displayed on the monitor 105, or supplied to the memory 106 and stored (recorded) in the memory 106.

[0115] By applying the imaging element 11 described above, the imaging device 101 configured in this way can, for example, capture images with higher image quality.

[0116] Examples of Image Sensor Use

[0117] Figure 18 This is a diagram illustrating an example of using the image sensor (imaging element) described above.

[0118] For example, the image sensor described above can be used to sense various types of light, such as visible light, infrared light, ultraviolet light, and X-rays.

[0119] • A device for taking images for appreciation, such as a digital camera, a portable device with camera functions, etc.

[0120] • Devices used in transportation, such as those for safe driving (e.g., automatic stopping) and driver status detection, include onboard sensors that capture images of the front, rear, surroundings, and interior of a vehicle, surveillance cameras that monitor vehicles and roads, and distance sensors that measure distances between vehicles.

[0121] • Devices for home appliances, such as televisions, refrigerators, or air conditioners, to capture images of user gestures and operate the device based on those gestures.

[0122] • Devices used in healthcare, such as endoscopes or devices that perform angiography by receiving infrared light.

[0123] • Security devices, such as surveillance cameras used for crime prevention or cameras used for personal identification.

[0124] • Devices used for beauty purposes, such as skin measuring instruments for photographing the skin or microscopes for photographing the scalp.

[0125] • Devices for sports, such as action cameras or wearable cameras for sports applications.

[0126] • Devices used in agriculture, such as cameras, for monitoring the condition of fields or crops.

[0127] Examples of combinations

[0128] Note that this technology may also have the following configurations.

[0129] (1) A solid-state imaging element, comprising:

[0130] Color filters, which are disposed on the back side of the semiconductor substrate that is exposed to light, with an insulating layer between them;

[0131] A waveguide, disposed between adjacent color filters, and formed of a low-refractive-index material with a refractive index lower than that of the color filters; and

[0132] A metal layer disposed on the semiconductor substrate side of the waveguide, and in the insulating layer closer to the semiconductor substrate side than the semiconductor substrate side of the color filter, the metal layer is configured such that the width of the lower portion closer to the semiconductor substrate side is narrower than the width of the upper portion closer to the waveguide side.

[0133] (2) The solid-state imaging element according to (1) above, wherein

[0134] The metal layer is configured such that the width of the upper portion is less than the width of the waveguide.

[0135] (3) The solid-state imaging element according to (1) or (2) above, wherein

[0136] The metal layer has a two-layer structure in which the upper and lower parts are formed of different kinds of metals.

[0137] (4) The solid-state imaging element according to (1) or (2) above, wherein

[0138] The metal layer has a single-layer structure in which the upper and lower portions are formed of the same type of metal.

[0139] (5) The solid-state imaging element according to any one of (1) to (4) above, wherein

[0140] The metal layer has a two-layer structure with a first metal layer and a second metal layer. The width of the first metal layer is less than the width of the waveguide, and the width of the second metal layer is narrower than the width of the first metal layer.

[0141] The second metal layer is formed to a depth near the semiconductor substrate.

[0142] (6) The solid-state imaging element according to any one of (1) to (5) above, wherein

[0143] The metal layer has a two-layer structure with a first metal layer and a second metal layer. The width of the first metal layer is less than the width of the waveguide, and the width of the second metal layer is narrower than the width of the first metal layer.

[0144] The metal layer is formed such that the width of the second metal layer is narrower than the width of the trench disposed between the pixels of the semiconductor substrate, and extends into the trench until the distal end of the second metal layer extends into the trench.

[0145] (7) The solid-state imaging element according to any one of (1) to (6) above, wherein

[0146] The height of the waveguide is lower than the height of the color filter.

[0147] (8) The solid-state imaging element according to any one of (1) to (7) above, wherein

[0148] The metal layer is configured in a curved shape that convexes toward the semiconductor substrate.

[0149] (9) The solid-state imaging element according to any one of (3) to (8) above, wherein

[0150] The metal layer is configured such that the width of the upper portion is narrower than the width of the waveguide.

[0151] (10) The solid-state imaging element according to any one of (1) to (9) above, wherein

[0152] The waveguide is configured to use air as the low refractive index material.

[0153] (11) The solid-state imaging element according to (10) above, wherein

[0154] The top surface of the waveguide is formed into a concave shape.

[0155] (12) The solid-state imaging element according to any one of (1) to (11) above, wherein

[0156] Trenches are formed in the semiconductor substrate to separate the pixels from each other, and an insulator is embedded in the trenches.

[0157] (13) The solid-state imaging element according to (12) above, wherein

[0158] The trench is formed by excavating from the back or front side of the semiconductor substrate.

[0159] (14) A method for manufacturing a solid-state imaging element, the method comprising:

[0160] Color filters are set up on the back side of the semiconductor substrate that is exposed to light, with an insulating layer between them;

[0161] A waveguide is provided, which is disposed between adjacent color filters and is formed of a low-refractive-index material with a refractive index lower than that of the color filters; and

[0162] A metal layer is disposed on the semiconductor substrate side of the waveguide, and in the insulating layer closer to the semiconductor substrate side than the semiconductor substrate side of the color filter, the metal layer is configured such that the width of the lower portion closer to the semiconductor substrate side is narrower than the width of the upper portion closer to the waveguide side.

[0163] (15) An electronic device comprising:

[0164] Solid-state imaging element, the solid-state imaging element comprising

[0165] Color filters, which are disposed on the back side of the semiconductor substrate that is exposed to light, with an insulating layer between them;

[0166] A waveguide, disposed between adjacent color filters, and formed of a low-refractive-index material with a refractive index lower than that of the color filters; and

[0167] A metal layer disposed on the semiconductor substrate side of the waveguide, and in the insulating layer closer to the semiconductor substrate side than the semiconductor substrate side of the color filter, the metal layer is configured such that the width of the lower portion closer to the semiconductor substrate side is narrower than the width of the upper portion closer to the waveguide side.

[0168] Note that this implementation scheme is not limited to the above-described scheme, and various modifications can be made without departing from the spirit of this disclosure. Furthermore, the effects described in this specification are merely illustrative and not restrictive; other effects may also exist.

[0169] List of reference numerals

[0170] 11 Imaging element, 12 Pixel, 21 Semiconductor substrate, 22 High dielectric constant film, 23 Insulating layer, 24 Color filter, 25 On-chip lens, 31 Waveguide, 32 Metal layer, 41 Metal film, 42 Waveguide component, 43 Groove

Claims

1. A solid-state imaging element, comprising: Color filters, which are disposed on the back side of the semiconductor substrate that is exposed to light, with an insulating layer between them; A waveguide, disposed between adjacent color filters, and formed of a low-refractive-index material with a refractive index lower than that of the color filters; and A metal layer disposed on the semiconductor substrate side of the waveguide, and in the insulating layer closer to the semiconductor substrate side than the semiconductor substrate side of the color filter, the metal layer is configured such that the width of the lower portion closer to the semiconductor substrate side is narrower than the width of the upper portion closer to the waveguide side.

2. The solid-state imaging element according to claim 1, wherein... The metal layer is configured such that the width of the upper portion is less than the width of the waveguide.

3. The solid-state imaging element according to claim 1, wherein... The metal layer has a two-layer structure in which the upper and lower parts are formed of different kinds of metals.

4. The solid-state imaging element according to claim 1, wherein... The metal layer has a single-layer structure in which the upper and lower portions are formed of the same type of metal.

5. The solid-state imaging element according to claim 1, wherein... The metal layer has a two-layer structure with a first metal layer and a second metal layer. The width of the first metal layer is less than the width of the waveguide, and the width of the second metal layer is narrower than the width of the first metal layer. The second metal layer is formed to a depth near the semiconductor substrate.

6. The solid-state imaging element according to claim 1, wherein... The metal layer has a two-layer structure with a first metal layer and a second metal layer. The width of the first metal layer is less than the width of the waveguide, and the width of the second metal layer is narrower than the width of the first metal layer. The metal layer is formed such that the width of the second metal layer is narrower than the width of the trench disposed between the pixels of the semiconductor substrate, and extends into the trench until the distal end of the second metal layer extends into the trench.

7. The solid-state imaging element according to claim 1, wherein... The height of the waveguide is lower than the height of the color filter.

8. The solid-state imaging element according to claim 1, wherein... The metal layer is configured in a curved shape that convexes toward the semiconductor substrate.

9. The solid-state imaging element according to claim 1, wherein... The metal layer is configured such that the width of the upper portion is narrower than the width of the waveguide.

10. The solid-state imaging element according to claim 1, wherein The waveguide is configured to use air as the low refractive index material.

11. The solid-state imaging element according to claim 10, wherein The top surface of the waveguide is formed into a concave shape.

12. The solid-state imaging element according to claim 1, wherein Trenches are formed in the semiconductor substrate to separate the pixels from each other, and an insulator is embedded in the trenches.

13. The solid-state imaging element according to claim 12, wherein... The trench is formed by excavating from the back or front side of the semiconductor substrate.

14. A method for manufacturing a solid-state imaging element, the method comprising: Color filters are set up on the back side of the semiconductor substrate that is exposed to light, with an insulating layer between them; A waveguide is provided, which is disposed between adjacent color filters and is formed of a low-refractive-index material with a refractive index lower than that of the color filters; and A metal layer is disposed on the semiconductor substrate side of the waveguide, and in the insulating layer closer to the semiconductor substrate side than the semiconductor substrate side of the color filter, the metal layer is configured such that the width of the lower portion closer to the semiconductor substrate side is narrower than the width of the upper portion closer to the waveguide side.

15. An electronic device comprising: Solid-state imaging element, the solid-state imaging element comprising Color filters, which are disposed on the back side of the semiconductor substrate that is exposed to light, with an insulating layer between them; A waveguide, disposed between adjacent color filters, and formed of a low-refractive-index material with a refractive index lower than that of the color filters; and A metal layer disposed on the semiconductor substrate side of the waveguide, and in the insulating layer closer to the semiconductor substrate side than the semiconductor substrate side of the color filter, the metal layer is configured such that the width of the lower portion closer to the semiconductor substrate side is narrower than the width of the upper portion closer to the waveguide side.

Images