Image pickup element, manufacturing method, and electronic device

Abstract

The present disclosure relates to an imaging element, a manufacturing method, and an electronic device configured to improve the effect of reducing crosstalk. The present invention includes: a groove portion, which is arranged on the light receiving surface side of a semiconductor substrate, a photoelectric conversion portion for photoelectrically converting light incident thereon is formed on the semiconductor substrate, and the groove portion is arranged between a plurality of photoelectric conversion portions; and a protrusion in a part of the groove portion, the protrusion being provided with at least an inclined surface inclined relative to the side surface of the groove portion to widen the gap of the groove portion. The present invention can be applied, for example, to a back-illuminated solid-state imaging element.

Description

Technical Field

[0001] The present disclosure relates to an image pickup element, a manufacturing method, and an electronic device, and more particularly to an image pickup element, a manufacturing method, and an electronic device that enable an improved effect of reducing crosstalk. Background Art

[0002] Conventionally, in solid-state imaging devices, particularly backlit solid-state imaging devices, crosstalk is known to occur from adjacent pixels. In particular, in solid-state imaging devices having a global shutter function, crosstalk with a charge storage unit causes an increase in stored charge, thereby causing degradation of the global shutter function.

[0003] Therefore, in order to avoid degradation of resolution and color reproducibility due to the occurrence of crosstalk, brightness difference, and the like, a technique of providing an element separation portion to separate adjacent pixels is used.

[0004] For example, Patent Document 1 proposes a structure that realizes optical pixel separation by forming a groove from the photodiode side of the back side to provide a groove penetrating from the front side to the back side of the semiconductor substrate or by providing a groove that does not penetrate some parts.

[0005] Furthermore, Patent Document 2 proposes a structure in which a semiconductor substrate and a horizontal light shielding portion are provided at the tip of a trench.

[0006] Reference List

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Publication No. 2013-30803

[0009] Patent Document 2: Japanese Patent Application Publication No. 2013-98446 Summary of the invention

[0010] Technical Problems Solved by the Invention

[0011] However, in the structure disclosed in the above-mentioned patent document 1, crosstalk occurs when light leaks to adjacent pixels due to diffraction of light at the ends of the grooves, and the effect of suppressing crosstalk is insufficient. In addition, in the structure disclosed in the above-mentioned patent document 2, if the volume of the shading portion is too large, not only the area of ​​the photodiode becomes smaller and the sensitivity decreases, but also crystal defects appear as the shading area increases.

[0012] The present disclosure has been made in view of such circumstances, and makes it possible to improve the effect of reducing crosstalk.

[0013] Solutions to technical problems

[0014] An imaging element according to one aspect of the present disclosure includes: a semiconductor substrate in which a photoelectric conversion portion for photoelectrically converting emitted light is formed; a groove portion, which is arranged between a plurality of the photoelectric conversion portions from the light receiving surface side of the semiconductor substrate; and a protrusion, which is provided with at least an inclined surface inclined relative to the side surface of the groove portion to widen the interval of the groove portion in a portion of the groove portion. Here, the inclined surface is formed, for example, by performing crystal anisotropic etching on a Si substrate using an etching solution, the thickness direction of the Si substrate being defined as a first direction and having a first crystal plane, the first crystal plane being represented by a plane index {111} extending along a horizontal plane orthogonal to the first direction. For example, in the case of etching using an alkaline solution, etching starts with a reaction between Si dangling bonds and OH ions. Therefore, etching is easy to perform as the number of dangling bonds exposed on the surface increases, and etching is not easy to perform as the number of back bonds extending to the body side increases. That is, the inclined surface has less than three Si back bonds in a direction substantially horizontal to the substrate surface. At the same time, the inclined surface has three Si back bonds in a direction substantially perpendicular to the surface of the Si substrate. For example, if in Fig.26 As described in the schematic diagram of , when the Si dangling bond side is in the positive direction relative to the normal line of the Si{111} plane, the Si back bond refers to the bond extending in the negative direction on the opposite side. Fig.26 The example of shows three back bonds at angles of -19.47° to 19.47° relative to the {111} plane. Specifically, in the case where a photoelectric conversion unit, an inclined surface, and a charge retention unit are provided in a Si{111} substrate, the inclined surface includes a surface along a second crystal plane of the Si{111} substrate, the second crystal plane of the Si{111} substrate being inclined relative to a first direction being a thickness direction of the Si substrate and represented by a plane index {111}.

[0015] According to one aspect of the present disclosure, a manufacturing method includes: digging out a groove portion, which is arranged between a plurality of photoelectric conversion portions from a light receiving surface side of a semiconductor substrate having a photoelectric conversion portion for photoelectrically converting emitted light; and forming a protrusion, which is provided with at least an inclined surface inclined relative to a side surface of the groove portion to widen the spacing of the groove portion in a portion of the groove portion.

[0016] An electronic device according to one aspect of the present disclosure includes an imaging element, which includes: a semiconductor substrate in which a photoelectric conversion portion for photoelectrically converting emitted light is formed; a groove portion which is arranged between a plurality of the photoelectric conversion portions from the light receiving surface side of the semiconductor substrate; and a protrusion which is provided with at least an inclined surface inclined relative to a side surface of the groove portion so as to widen the spacing of the groove portion in a portion of the groove portion.

[0017] According to one aspect of the present disclosure, a groove portion is dug out, the groove portion is arranged between a plurality of photoelectric conversion portions from the light receiving surface side of a semiconductor substrate having a photoelectric conversion portion for photoelectric conversion of emitted light; and a protrusion portion is formed, the protrusion portion being provided with at least an inclined surface inclined relative to the side surface of the groove portion so as to widen the interval of the groove portion in a portion of the groove portion. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a diagram describing a basic configuration example of an element separation section included in an image pickup element to which the present technology is applied.

[0019] Figure 2 is a diagram showing a two-dimensional arrangement example of element separation parts.

[0020] Figure 3 is a cross-sectional view showing a first structural example of an image pickup element.

[0021] Figure 4 is a cross-sectional view showing a second configuration example of the image pickup element.

[0022] Figure 5 is a cross-sectional view showing a third structural example of the image pickup element.

[0023] Figure 6 is a cross-sectional view showing a fourth configuration example of the image pickup element.

[0024] Figure 7 It is a diagram showing a modified example of the element separation portion.

[0025] Figure 8 is a cross-sectional view showing a fifth structural example of the image pickup element.

[0026] Fig. 9 is a cross-sectional view showing a sixth structural example of the image pickup element.

[0027] Fig.10 It is a diagram describing the relationship between the protrusion and the opening when viewed two-dimensionally.

[0028] Fig.11 is a cross-sectional view showing a seventh structural example of the image pickup element.

[0029] Fig.12 is a cross-sectional view showing an eighth structural example of the image pickup element.

[0030] Fig.13 is a cross-sectional view showing a ninth structural example of the image pickup element.

[0031] Fig.14 It is a diagram showing an example of a two-dimensional arrangement of an element separation unit.

[0032] Fig.15 is a diagram for describing a first manufacturing method.

[0033] Fig.16 is a diagram for describing the second manufacturing method.

[0034] Fig.17 is a diagram for describing a third manufacturing method.

[0035] Fig.18 is a diagram for describing a fourth manufacturing method.

[0036] Fig.19 is a diagram for describing a fifth manufacturing method.

[0037] Fig. 20 is a diagram for describing a fifth manufacturing method.

[0038] Fig.21 is a diagram for describing a sixth manufacturing method.

[0039] Fig. 22 is a diagram for describing a seventh manufacturing method.

[0040] Fig.23 is a diagram for describing an eighth manufacturing method.

[0041] Fig.24 is a block diagram showing a configuration example of an image pickup apparatus.

[0042] Fig.25 is a diagram showing a usage example using an image sensor.

[0043] Fig.26 Schematic diagram illustrating back bonds on a crystal plane of a Si substrate of the present disclosure.

[0044] Fig. 27 is a schematic diagram for describing the deflection angle on the surface of the Si substrate of the present disclosure. DETAILED DESCRIPTION

[0045] Specific embodiments to which the present technology is applied will be described in detail below with reference to the drawings.

[0046] <Basic Configuration Example of Element Separation Section Including Protrusion>

[0047] refer to Figure 1 , a basic configuration example of an element separation section included in an image pickup element to which the present technology is applied will be described.

[0048] Figure 1 A shows an example of a cross-sectional structure of a general element separation portion. Figure 1 B shows an example of a cross-sectional structure of an element separation portion having a protruding shape, Figure 1 C shows an enlarged protrusion shape.

[0049] For example, Figure 1 As shown in A, the element separation part 21 is generally formed by vertically digging a groove obtained by digging the back side (or front side) of the semiconductor substrate 11. In addition, as shown in the figure, the two element separation parts 21a and 21b separate the pixel arranged therebetween from other adjacent pixels. In addition, in the element separation part 21, a groove side 22 substantially perpendicular to the back side of the semiconductor substrate 11 is formed, and a flat part 23 having a flat surface substantially perpendicular to the groove side 22 is formed on the bottom surface of the element separation part 21.

[0050] In contrast, Figure 1 As shown in FIG. 1B, at the tip of the element separation portion 31 to which the present technology is applied, a protrusion 33 having a substantially diamond shape when viewed from a cross section is formed to widen the space of the groove side 32 obtained by vertically digging the back side (or front side) of the semiconductor substrate 11. In addition, as shown in the figure, the two element separation portions 31a and 31b separate the pixel disposed therebetween from other adjacent pixels.

[0051] And, if Figure 1 As shown in FIG. 3C , when viewed in cross section, the protrusion 33 includes a plurality of inclined surfaces 41 to 44 that are inclined relative to the groove side surface 32 forming the element separation portion 31 .

[0052] For example, the inclined surfaces 41 and 42 are formed at a predetermined inclination angle relative to the bottom surface when the semiconductor substrate 11 is vertically dug to form the groove (for example, the surface that becomes the flat portion 23 in the element separation portion 21) so as to extend in an inclined direction on the far side of the groove. In addition, the inclined surfaces 43 and 44 are formed at a predetermined inclination angle relative to the bottom surface when the semiconductor substrate 11 is vertically dug to form the groove so as to extend in an inclined direction on the opening side of the groove.

[0053] Specifically, the protrusion 33 can be formed to have a substantially rhombus shape by performing silicon plane orientation selective etching on the Si substrate (100) using an alkaline chemical solution, thereby exposing the silicon plane (111) having a low etching rate. Through this operation, for example, the inclined surfaces 41 and 42 are formed at an inclination angle of 54.7° relative to the bottom surface when the semiconductor substrate 11 is vertically excavated to form a groove. That is, the protrusion 33 includes the inclined surfaces 41 to 44 inclined along the plane direction of the silicon plane (111) of the silicon crystal constituting the semiconductor substrate 11.

[0054] And, in Figure 1 In A and B of FIG. 1 , light incident on the semiconductor substrate 11 is represented by dotted arrows.

[0055] like Figure 1As shown in A of FIG. 1 , in a certain pixel, light traveling along the element separation portion 21 in the semiconductor substrate 11 is refracted toward another pixel adjacent to the pixel at the tip of the element separation portion 21. Therefore, in the solid-state imaging element including the element separation portion 21, color mixing (crosstalk) occurs due to light leakage to another pixel.

[0056] In contrast, Figure 1 As shown in B, in a certain pixel, light traveling along the element separation portion 31 in the semiconductor substrate 11 is refracted in the direction of the pixel itself at the protrusion 33 of the element separation portion 31. Therefore, in a solid-state imaging element including the element separation portion 31, it is possible to prevent light from leaking to another pixel and suppress the occurrence of color mixing.

[0057] <Two-dimensional layout example of component separation>

[0058] refer to Figure 2 , a two-dimensional arrangement of the element separation portion 31 including the protrusion 33 will be described.

[0059] A plurality of pixels that receive light transmitted through the color filter are arranged in a matrix on a light receiving surface of the solid-state imaging element. Figure 2 An example is shown in which one pixel R receiving red light, two pixels G receiving green light, and one pixel B receiving blue light are arranged in 2×2 according to the so-called Bayer array.

[0060] For example, Figure 2 As shown in FIG. 1A , the element separation portion 31 including the protrusion 33 may be arranged at the boundary of a plurality of pixels in a grid pattern to separate all the pixels R, G, and B.

[0061] In addition, if Figure 2 As shown in FIG. 1B, the element separation part 31 including the protrusion 33 can be arranged to surround the pixel R among the pixel R, the pixel G, and the pixel B. In such an arrangement example, the element separation part 21 including the flat part 23 is arranged at a position other than around the pixel R. That is, the red light penetrates deep into the semiconductor substrate 11, thereby easily causing color mixing. By arranging the element separation part 31 including the protrusion 33 to surround at least the pixel R, the occurrence of color mixing can be reduced.

[0062] In addition, if Figure 2 As shown in C and D of FIG. 1 , the element separation portion 31 including the protrusion 33 may be formed so as not to be continuous at the intersection of the grid shape that is the boundary of the plurality of pixels but to be discontinuous at the intersection. For example, in order to suppress the micro-loading effect caused by the difference in etching speed at the intersection, it is preferable to form the element separation portion 31 so as to be discontinuous at the intersection in this way.

[0063] Figure 2The element separation portion 31 shown in C is formed in a shape such that both end portions are flat when viewed two-dimensionally, and has a shape that prevents the element separation portions 31 from overlapping each other at intersections. Figure 2 The element separation portion 31 shown in D is formed to have a protruding shape so that both end portions are inclined at about 45 degrees when viewed two-dimensionally, and has a shape that reduces the overlapping portion of the element separation portion 31 at the intersection.

[0064] Note that except Figure 2 In addition to the arrangement example shown, for example, in the case where pixels exist in a single line or a single point, regardless of the micro-loading effect, the element separation section 31 may be continuously formed to surround each pixel (for example, without making the pixel Figure 2 B and C are shown as discontinuous at the intersection).

[0065] <Structure Example of Image Pickup Element>

[0066] refer to Figures 3 to 14 , a configuration example of an image pickup element including an element separation portion 31 having a protrusion 33 will be described.

[0067] Figure 3 A cross-sectional view showing a first configuration example of an image pickup element is shown.

[0068] like Figure 3 As shown, the imaging element 51 is structured such that a planarization film 12, a color filter layer 13, and an on-chip lens layer 14 are stacked on the back side of a semiconductor substrate 11, and a wiring layer 15 is stacked on the surface side of the semiconductor substrate 11. That is, the imaging element 51 is a backlight type that irradiates light to the back side of the semiconductor substrate 11. Here, for example, the semiconductor substrate 11 includes a Si{111} substrate. The Si{111} substrate is a single crystal silicon substrate having a crystal orientation of {111}.

[0069] In addition, the imaging element 51 has a structure in which a plurality of pixels 52 are arranged in a matrix form when viewed two-dimensionally. Figure 3 A cross section of two (pixels 52a and 52b) of the pixels 52 is shown. Furthermore, in the image pickup element 51 , in each pixel 52 , a color filter 53 is arranged in the color filter layer 13 , and a microlens 54 is arranged in the on-chip lens layer 14 .

[0070] And, if Figure 3 As shown in FIG. 1A , the image pickup element 51 - 1 has a structure in which the pixel 52 a and the pixel 52 b are separated by the element separation portion 31 including the protrusion 33 . Figure 1As described in B, the element separation portion 31 includes a rhombus-shaped protrusion 33, which is formed by digging a groove to form a groove side 32 perpendicular to the back side of the semiconductor substrate 11, and performing silicon plane orientation selective etching at the tip of the groove using an alkaline chemical solution. In addition, the element separation portion 31 has a structure including a light shielding portion 34, which is formed by burying a desired material such as a metal in the groove, and the material is two-dimensionally formed on the back side of the semiconductor substrate 11.

[0071] In this manner, in the imaging element 51-1 having a structure in which adjacent pixels 52 are separated from each other by the element separation section 31, light (dashed arrow) incident on the pixel 52a is refracted in the direction of the pixel 52a by the protrusion 33 of the element separation section 31. Therefore, the imaging element 51-1 can prevent light from leaking from the pixel 52a to the pixel 52b, that is, prevent the occurrence of color mixing.

[0072] at the same time, Figure 3 B shows an imaging element 51-2 having a structure in which the element separation section 21 including the flat portion 23 separates adjacent pixels 52 from each other. In addition, the element separation section 21 has a structure having a light shielding portion 24 similar to the element separation section 31. And, as shown in the figure, in the imaging element 51-2, light leaks to another adjacent pixel 52 at the tip portion of the element separation section 21.

[0073] Therefore, the image pickup element 51 - 1 can suppress the degradation of image quality due to the occurrence of color mixing better than the image pickup element 51 - 2 , and can capture a higher quality image.

[0074] Figure 4 A cross-sectional view showing a second configuration example of an image pickup element is shown. Figure 4 In the imaging element 51A shown in FIG. Figure 3 Configurations common to the imaging element 51 are denoted by the same reference numerals, and a detailed description thereof will be omitted.

[0075] like Figure 4 As shown, the imaging elements 51A-1 and 51A-2 have Figure 3 The imaging elements 51-1 and 51-2 are constructed differently, and in each pixel 52, an inner lens 55 is formed inside a planarization film 12A laminated on a semiconductor substrate 11A. In addition, a groove side surface 32 and a protrusion 33 are formed by digging the semiconductor substrate 11A, a light shielding portion 35 is formed on the back surface of the semiconductor substrate 11A, and an element separation portion 31A is formed between the light shielding portion 35 and the inner lens 55 of the color filter layer 13.

[0076] Therefore, if Figure 4As shown in A, the imaging element 51A-1 can prevent light from leaking from the pixel 52a to the pixel 52b by the element separation unit 31A.

[0077] At the same time, if Figure 4 As shown in FIG. 8B , in the imaging element 51A- 2 , light leaks to another adjacent pixel 52 at the tip portion of the element separation portion 21A.

[0078] The image pickup element 51A-1 constructed in this manner can be used in the same manner as Figure 3 The image pickup element 51 - 1 suppresses the degradation of image quality due to the occurrence of color mixing in a similar manner, and can capture an image of higher quality.

[0079] Figure 5 A cross-sectional view showing a third configuration example of an image pickup element is shown. Figure 5 In the imaging element 51B shown in FIG. Figure 3 Configurations common to the imaging element 51 are denoted by the same reference numerals, and detailed descriptions thereof will be omitted.

[0080] like Figure 5 As shown, the imaging element 51B-1 has Figure 3 The imaging element 51 - 1 has a different structure from that of the imaging element 51 - 1 , in which the element isolation portion 31B is formed in the semiconductor substrate 11B up to the vicinity of the wiring layer 15 .

[0081] Therefore, as Figure 5 In the imaging element 51B-1, the light incident on the pixel 52a (dashed arrow) is refracted by the protrusion 33 of the element separation section 31B in the direction of the pixel 52a. In addition, in the imaging element 51B-1, since the element separation section 31B is formed near the wiring layer 15, it is possible to make it difficult for the light incident on the pixel 52a to hit the wiring near the adjacent pixel 52b. Through this operation, the imaging element 51B-1 can more reliably prevent light from leaking from the pixel 52a to the pixel 52b, that is, the effect of preventing color mixing is improved.

[0082] In addition, if Figure 5 As shown in FIG. 1B , even in the imaging element 51B- 2 , the element isolation portion 21B is formed to reach the vicinity of the wiring layer 15 .

[0083] However, as shown in the figure, in the image pickup element 51B-2, light hits the wiring near the adjacent pixel 52b at the tip portion of the element separation portion 21B and is scattered by the wiring, and the scattered light is incident on the adjacent pixel 52b.

[0084] The image pickup element 51B-1 constructed in this manner can be used in the same manner as Figure 3The image pickup element 51 - 1 suppresses the degradation of image quality due to the occurrence of color mixing in a similar manner, and can capture an image of higher quality.

[0085] Figure 6 A cross-sectional view showing a fourth configuration example of an image pickup element is shown. Figure 6 In the imaging element 51C shown in FIG. Figure 4 Configurations common to the image pickup element 51A are denoted by the same reference numerals, and a detailed description thereof will be omitted.

[0086] That is, in the imaging elements 51C-1 and 51C-2, the inner lens 55 is formed in each pixel 52 in a manner similar to the imaging elements 51A-1 and 51A-2. Figure 5 In a similar manner to the imaging element 51B- 1 , the element separation portion 31C is formed up to the vicinity of the wiring layer 15 in the semiconductor substrate 11C.

[0087] The imaging element 51C-1 constructed in this manner can be used in the same manner as Figure 3 The imaging element 51A-1 and Figure 5 The image pickup element 51B-1 suppresses the degradation of image quality due to the occurrence of color mixing in a similar manner, and can capture an image of higher quality.

[0088] here, Figure 7 A modified example of the element separation unit 31 is shown.

[0089] Figure 7 The element separation portion 31' shown in A includes a groove side 32' formed to penetrate the semiconductor substrate 11, and includes a substantially triangular shape (for example, Figure 1 That is, the protrusion 33 is not limited to a substantially rhombus shape, and may adopt various shapes as long as the shape protrudes from the groove side 32 in the side direction.

[0090] Figure 7 The element separation portion 31" shown in B has a roughly diamond-shaped protrusion 33" in the middle section of the groove side 32" formed by digging the semiconductor substrate 11. That is, the protrusion 33 is not limited to being formed in the tip portion of the element separation portion 31, but at least needs to have a structure arranged between the light receiving surface of the semiconductor substrate 11 and the tip of the element separation portion 31" (i.e., the bottom of the groove).

[0091] Even in the element separation portion 31 ′ and the element separation portion 31 ″ of such a shape, in a manner similar to the above-described element separation portion 31 , light incident on the semiconductor substrate 11 can be prevented from leaking to another pixel, and the occurrence of color mixing can be suppressed.

[0092] Figure 8 A cross-sectional view showing a fifth configuration example of an image pickup element is shown. Figure 8 In the imaging element 51D shown in FIG. Figure 4 Configurations common to the image pickup element 51A are denoted by the same reference numerals, and a detailed description thereof will be omitted.

[0093] Right now, Figure 8 The imaging element 51D shown in FIG. 1 has a global shutter function of transferring charges from a photodiode to a charge storage unit 62 at substantially the same timing in all pixels, and has a configuration in which the photodiode and the charge storage unit 62 are arranged vertically. Also, the imaging element 51D has a configuration in which the charge storage unit 62 is shielded from light by a light shielding wall 61 extending in the horizontal direction within the semiconductor substrate 11D, and the charge storage unit 62 and the photodiode are separated from each other. In addition, an opening is provided in the light shielding wall 61, and the opening is used to provide a vertical transistor (not shown) for transferring charges from the photodiode to the charge storage unit 62.

[0094] Therefore, as Figure 8 The imaging element 51D- 1 can prevent the light reflected by the element separation portion 31D from leaking to the charge storage unit 62 , as indicated by the dotted arrow in A. The imaging element 51D- 1 can reflect the light reflected by the element separation portion 31D toward the horizontal light shielding wall 61 .

[0095] At the same time, if Figure 8 As shown in FIG. 8B , in the imaging element 51D- 2 , the light propagating along the element separation portion 21D reaches the charge storage unit 62 .

[0096] In the image pickup element 51D- 1 configured in this manner, the storage charge of the charge storage unit 62 can be prevented from increasing by preventing light from leaking to the charge storage unit 62 , and the global shutter function can be reliably realized.

[0097] Fig. 9 A cross-sectional view showing a sixth configuration example of an image pickup element is shown. Fig. 9 In the imaging element 51E shown in FIG. Figure 8 Configurations common to the image pickup element 51D are denoted by the same reference numerals, and a detailed description thereof will be omitted.

[0098] That is, the imaging element 51E is Figure 8The imaging element 51D has a global shutter function in a similar manner, and an opening is provided in the light shielding wall 61 , the opening being used to provide a vertical transistor (not shown) for transferring charges from the photodiode to the charge storage unit 62 .

[0099] Furthermore, in the imaging element 51E, the protrusion 33E of the element separation portion 31E is formed in the middle section of the groove side surface 32 such that the horizontal dimension of the protrusion 33E is larger than the opening of the light shielding wall 61 .

[0100] That is, Fig.10 As shown, when the imaging element 51E is viewed two-dimensionally, the protrusion 33E of the element separation section 31E is formed to be wider than the opening 63 of the light shielding wall 61. Note that in the region other than the opening 63 of the light shielding wall 61, the imaging element 51E is configured to separate adjacent pixels 52 by the element separation section 21 including the flat portion 23.

[0101] Through this construction, Figure 8 Compared with the imaging element 51D, the imaging element 51E can more reliably prevent light from leaking to the charge storage unit 62 .

[0102] Fig.11 A cross-sectional view showing a seventh configuration example of an image pickup element is shown. Fig.11 In the imaging element 51F shown in FIG. Figure 3 Configurations common to the imaging element 51 are denoted by the same reference numerals, and a detailed description thereof will be omitted.

[0103] The image pickup element 51F has a global shutter function, and has a configuration in which a photodiode and a charge storage unit 62 are arranged in the horizontal direction.

[0104] In the image pickup element 51F having such a configuration, the charge storage unit 62 is shielded from light by the light shielding portion 36 and the light shielding wall 37 , and the element separation portion 31 including the protrusion 33 is formed between the photodiode and the charge storage unit 62 .

[0105] Therefore, as Fig.11 The imaging element 51F- 1 can prevent the light indicated by the dotted arrow in A from leaking to the charge storage unit 62 by reflecting the light reflected by the element separation unit 31F toward the photodiode side.

[0106] At the same time, if Fig.11 As shown in FIG. 8B , in the imaging element 51F- 2 , light propagating along the element separation portion 21F including the flat portion 23 is diffracted at the tip of the element separation portion 21F and leaks to the charge storage unit 62 .

[0107] In the image pickup element 51F- 1 configured in this manner, the storage charge of the charge storage unit 62 can be prevented from increasing by preventing light from leaking to the charge storage unit 62 , and the global shutter function can be reliably realized.

[0108] Fig.12 A cross-sectional view showing an eighth configuration example of an image pickup element is shown. Fig.12 In the imaging element 51G shown in FIG. Figure 3 Configurations common to the imaging element 51 are denoted by the same reference numerals, and a detailed description thereof will be omitted.

[0109] The imaging element 51G has a global shutter function, and the floating diffusion (FD) portion 64 is used as a charge storage unit for storing charges transferred from the photodiode. Also, in the imaging element 51G, the light shielding portion 36 is provided to shield the FD portion 64 from light, and the element separation portion 31 including the protrusion 33 is formed to surround the FD portion 64 from the light shielding portion 36.

[0110] Therefore, as Fig.12 The imaging element 51G- 1 can prevent the light indicated by the dotted arrow in A from leaking to the FD portion 64 by reflecting the light reflected by the element isolation portion 31G toward the photodiode side.

[0111] At the same time, if Fig.12 As shown in FIG. 8B , in the imaging element 51G- 2 , light propagating along the element separation portion 21G including the flat portion 23 is diffracted at the tip of the element separation portion 21G and leaks to the FD portion 64 .

[0112] In the image pickup element 51G- 1 configured in this manner, the storage charge of the FD portion 64 can be prevented from increasing by preventing light from leaking to the FD portion 64 , and the global shutter function can be reliably realized.

[0113] Fig.13 A cross-sectional view showing a ninth configuration example of an image pickup element is shown. Fig.13 In the imaging element 51H shown in FIG. Figure 3 Configurations common to the imaging element 51 are denoted by the same reference numerals, and a detailed description thereof will be omitted.

[0114] The imaging element 51H has a structure in which two photodiodes are formed in one pixel 52. In addition to the separation of adjacent pixels 52 by the element separation unit 31, the two photodiodes in the pixel 52 are also separated.

[0115] In a manner similar to the element separation portion 31, Fig.13A shows an image pickup element 51H-1 having a configuration in which two photodiodes in a pixel 52 are separated by an element separation unit 71 including a protrusion 73. At the same time, in a manner similar to the element separation unit 21, Fig.13 B shows an image pickup element 51H- 2 having a configuration in which two photodiodes in a pixel 52 are separated by an element separation portion 81 including a flat portion 83 .

[0116] For example, something like Fig.13 Regarding the light indicated by the dotted arrow in A, there is a concern that the light reflected by the protrusion 73 of the element isolation portion 71 that isolates the photodiode in the imaging element 51H- 1 may leak to the adjacent pixel 52 .

[0117] On the contrary, something like Fig.13 The light indicated by the dotted arrow in B is reflected by the element isolation portion 81 that separates the photodiode in the imaging element 51H- 2 and does not leak to the adjacent pixel 52 .

[0118] Therefore, in a structure in which two photodiodes are formed in one pixel 52 as in the imaging element 51H- 2 , it is preferable to separate the photodiodes using an element separation portion 81 including a flat portion 83 , and to separate the pixels 52 from each other using an element separation portion 31 including a protrusion 33 .

[0119] refer to Fig.14 , a two-dimensional arrangement of the element separation portion 31 including the protrusion 33 will be described.

[0120] As mentioned above Fig. 9 The imaging element 51E, Fig.14 A shows an arrangement example: in a configuration in which an opening 63 is formed on a light shielding wall 61, the element separation portion 31 including the protrusion 33 is arranged only at a position passing through the opening 63. In addition, in this arrangement example, the element separation portion 21 including the flat portion 23 is provided outside the position passing through the opening 63.

[0121] As mentioned above Fig.11 As in the imaging element 51F, in a configuration in which the photodiode PD and the charge storage unit 62 are arranged in the horizontal direction, Fig.14 B shows an arrangement example: the element separation section 31F including the protruding portion 33 is arranged only at a position where the photodiode PD and the charge storage unit 62 are separated. Furthermore, in this arrangement example, the element separation section 21 including the flat portion 23 is provided between pixels.

[0122] Similar to the above Fig.12 The imaging element 51G, Fig.14C shows an arrangement example: in a configuration in which the FD portion 64 is formed, the element separation portion 31G including the protruding portion 33 is arranged only at a position around the FD. In addition, in this arrangement example, the element separation portion 21 including the flat portion 23 is provided between pixels.

[0123] <Method for Manufacturing Imaging Element>

[0124] refer to Figures 15 to 23 , a process of forming an element separation portion 31 or an element separation portion 21 in a method for manufacturing an imaging element to which the present technology is applied will be described. Note that the following manufacturing method uses a Si{111} substrate as a semiconductor substrate, the thickness direction of the Si{111} substrate being defined as a first direction, having a first crystal plane represented by a plane index {111} extending along a horizontal plane perpendicular to the first direction. And, the inclined surface of the protrusion is formed by performing crystal anisotropic etching on the silicon {111} substrate using an etching solution so that it includes a plane along a second crystal plane of the Si{111} substrate represented by a plane index {111} and inclined relative to the first direction. In addition, in the Si{111} substrate, <110> The etching rate in the direction (i.e., in the direction with one or two Si back bonds) is higher than that in the <111> The etching rate in the direction (ie, in the direction with three Si back bonds) is sufficiently high.

[0125] refer to Fig.15 , the first manufacturing method will be described.

[0126] In the first step, if Fig.15 As shown in the first row from the top, a silicon nitride (Si3N4) film is formed on the entire back surface of the semiconductor substrate 11, and the silicon nitride film is removed only in the region where the groove 102 is formed, thereby forming a hard mask 101. Then, the groove 102 is processed by etching the semiconductor substrate 11 using the hard mask 101. Through this operation, the side surface 103 of the groove 102 is formed to be approximately perpendicular to the back surface of the semiconductor substrate 11, and the bottom surface 104 of the groove 102 is formed to be flat.

[0127] In the second step, if Fig.15 As shown in the second row from the top, a sidewall film 105 is formed on the side 103 of the trench 102. For example, the sidewall 105 is formed by forming a silicon nitride film on the entire inner surface of the trench 102 and then etching back the bottom surface portion of the trench 102 to remove the silicon nitride film.

[0128] In the third step, if Fig.15 As shown in the third row from the top, the semiconductor substrate 11 is etched back to dig down the bottom surface 104 of the trench 102 to form a bottom surface 106 of the trench 102 so as to be deeper than the sidewall 105. Note that the etch back in the third step may be optional.

[0129] In the fourth step, if Fig.15 As shown in the fourth row from the top, alkaline etching is performed on the semiconductor substrate 11 to form a protrusion 107 extending in a rhombus shape at the bottom of the trench 102. That is, by using an alkaline chemical solution to perform silicon plane-oriented selective etching to expose a silicon surface (111) with a low etching rate, the protrusion 107 of the trench 102 can be formed into a rhombus shape extending beyond the side 103.

[0130] In the fifth step, if Fig.15 As shown in the fifth row from the top, by burying a desired material such as metal in the trench 102, an element separation portion 31 including a rhombus-shaped protrusion 33 protruding in the side direction from the trench side 32 is formed.

[0131] refer to Fig.16 , the second manufacturing method will be described. For example, the second manufacturing method is a manufacturing method of separately manufacturing the element separation portion 31 including the protruding portion 33 and the element separation portion 21 including the flat portion 23 .

[0132] In the eleventh step, if Fig.16 The first row from the top is shown in the same way as above. Fig.15 The first step processes the grooves 102-1 and 102-2 in a similar manner.

[0133] In the twelfth step, if Fig.16 As shown in the second row from the top, a silicon nitride film is formed on the entire inner surface of the trenches 102-1 and 102-2. Through this operation, a side wall 105-1 is formed on the side 103-1 of the trench 102-1, and a mask 108-1 is formed on the bottom surface 104-1 of the trench 102-1. At the same time, a side wall 105-2 is formed on the side 103-2 of the trench 102-2, and a mask 108-2 is formed on the bottom surface 104-2 of the trench 102-2. In addition, a resist 111 is applied so as to be buried in the trench 102-2.

[0134] In the thirteenth step, if Fig.16 As shown in the third row from the top, the bottom surface portion of the trench 102-1 is etched back to remove the mask 108-1, and then the resist 111 is removed. Through this operation, the semiconductor substrate 11 is exposed on the bottom surface 104-1 of the trench 102-1.

[0135] In the fourteenth step, if Fig.16 As shown in the fourth row from the top, alkaline etching is performed on the semiconductor substrate 11 to form a protrusion 107 extending in a rhombus shape at the bottom of the trench 102-1. At this time, the bottom of the trench 102-2 is not processed due to the mask 108-2.

[0136] Thereafter, by removing the silicon nitride film and burying a desired material such as metal in the trenches 102 - 1 and 102 - 2 , the element separation portions 31 - 1 and 31 - 2 including the protrusions 33 - 1 and 33 - 2 are formed to different depths, respectively.

[0137] refer to Fig.17 , the third manufacturing method will be described. For example, the third manufacturing method is to separately manufacture the element separation part 31E including the protrusion 33E in the middle section (see Fig. 9 ) and a method for manufacturing an element separation portion 21 including a flat portion 23.

[0138] In the twenty-first step, a silicon oxide (SiO2) film is formed on the back side of the semiconductor substrate 11 to form a hard mask 101, and the semiconductor substrate 11 is etched, thereby processing the trenches 102-1 and 102-2. Subsequently, a silicon oxide film is formed inside the trenches 102-1 and 102-2, and the silicon oxide film on the bottom surface 104-1 of the trench 102-1 and the bottom surface 104-2 of the trench 102-2 is removed by etching back. Through this operation, a side wall 105-1 is formed on the side surface 103-1 of the trench 102-1, and a side wall 105-2 is formed on the side surface 103-2 of the trench 102-2.

[0139] Then, a resist (not shown) is applied so as to be buried in the trench 102-2, and the semiconductor substrate 11 is etched so as to dig down only the bottom surface 104-1 of the trench 102-1. Furthermore, the resist is removed from the trench 102-2, a silicon nitride film is formed inside the trenches 102-1 and 102-2, and the silicon nitride film on the bottom surface 104-1 of the trench 102-1 and the bottom surface 104-2 of the trench 102-2 is removed by etching back.

[0140] By doing this, Fig.17 As shown in the first row from the top, a silicon nitride film 112-1 is formed on the side 103-1 of the trench 102-1, and a silicon nitride film 112-2 is formed on the side 103-2 of the trench 102-2.

[0141] In the 22nd step, the bottom surface 104-1 of the trench 102-1 and the bottom surface 104-2 of the trench 102-2 are dug downward by etching the semiconductor substrate 11, and a silicon oxide film is formed on the dug portions. Fig.17 As shown in the second row from the top, a hard mask 113-1 is formed in a region in the trench 102-1 where the silicon nitride film 112-1 is not formed, and a hard mask 113-2 is formed in a region in the trench 102-2 where the silicon nitride film 112-2 is not formed.

[0142] In the twenty-third step, if Fig.17 As shown in the third row from the top, the silicon nitride film 112-1 and the silicon nitride film 112-2 are washed away. By this operation, the semiconductor substrate 11 is exposed in the middle section of the side 103-1 of the trench 102-1, while the side 103-2 of the trench 102-2 is covered by the side wall 105-2 and the hard mask 113-2.

[0143] In the twenty-fourth step, the semiconductor substrate 11 is alkali etched, and the semiconductor substrate 11 exposed in the middle section of the side surface 103-1 of the groove 102-1 is etched selectively in the silicon plane orientation to form the protrusion 109-1. Then, by removing the silicon oxide film, as shown in FIG. Fig.17 As shown in the fourth row from the top, the groove 102-1 including the protrusion 109-1 in the middle section and the groove 102-2 including the bottom surface 104 formed flat can be manufactured respectively.

[0144] Thereafter, by burying a desired material such as metal in the grooves 102-1 and 102-2, an element separation portion 31E including a protrusion 33E in the middle section is formed (see FIG. Fig. 9 ) and an element separation portion 21 including a flat portion 23.

[0145] refer to Fig.18 , a fourth manufacturing method will be described. For example, the fourth manufacturing method is a manufacturing method of manufacturing the element separation portions 31 including the protrusions 33 of different sizes, respectively.

[0146] In the thirty-first step, a silicon oxide film is formed on the back surface of the semiconductor substrate 11 to form a hard mask 101, and the semiconductor substrate 11 is etched, thereby processing the trenches 102-1 and 102-2. Subsequently, a silicon oxide film is formed inside the trenches 102-1 and 102-2, and the silicon oxide film on the bottom surface 104-1 of the trench 102-1 and the bottom surface 104-2 of the trench 102-2 is removed by etching back. Through this operation, a side wall 105-1 is formed on the side surface 103-1 of the trench 102-1, and a side wall 105-2 is formed on the side surface 103-2 of the trench 102-2.

[0147] Then, silicon nitride films are formed inside the trenches 102-1 and 102-2. At this time, in the trench 102-1, a silicon nitride film 112 is formed on the side surface 103-1, and in the trench 102-2, a silicon nitride film 114 is formed so as to be buried inside the trench 102-2. Fig.18 As shown in the first row from the top, resist 115 is applied to the side of trench 102-2.

[0148] In the thirty-second step, after removing the resist 115, the semiconductor substrate 11 is etched. Fig.18As shown in the second row from the top, the trench 102 - 1 is dug downward to form a bottom surface 106 - 1 .

[0149] In the thirty-third step, the silicon nitride film 112 and the silicon nitride film 114 are removed. By this operation, Fig.18 As shown in the third row from the top, in the trench 102-1, the semiconductor substrate 11 is exposed at the tip portion of the side surface 103-1 and the bottom surface 106-1, and in the trench 102-2, the semiconductor substrate 11 is exposed only on the bottom surface 104-2.

[0150] In the thirty-fourth step, the semiconductor substrate 11 is alkali-etched, and the semiconductor substrate 11 exposed at the tip of the side surface 103-1 and the bottom surface 106-1 in the groove 102-1 is etched selectively in the silicon plane orientation to form the protrusion 107-1. At the same time, the semiconductor substrate 11 exposed on the bottom surface 106-1 in the groove 102-2 is etched selectively in the silicon plane orientation to form the protrusion 107-2.

[0151] That is, Fig.18 As shown in the fourth row from the top, a protrusion 107-1 having a larger shape in the tip portion of the groove 102-1 and a protrusion 107-2 having a smaller shape in the tip portion of the groove 102-2 may be manufactured, respectively.

[0152] Thereafter, by burying a desired material such as metal in the trenches 102 - 1 and 102 - 2 , the element separation portion 31 including the protrusions 33 each having a different size is formed.

[0153] refer to Fig.19 and Fig. 20 , a fifth manufacturing method will be described. For example, the fifth manufacturing method is a method of manufacturing the element separation portion 31 including a plurality of protrusions 33 .

[0154] In the forty-first step, a silicon oxide film is formed on the back surface of the semiconductor substrate 11 to form a hard mask 101, and the semiconductor substrate 11 is etched to process the trench 102. Fig.19 As shown in the first row from the top, a silicon oxide film is formed inside the trench 102 , and the silicon oxide film on the bottom surface 104 of the trench 102 is removed by etching back, thereby forming a sidewall 105 on the side surface 103 of the trench 102 .

[0155] In the forty-second step, the bottom surface 104 of the trench 102 is dug downward by etching the semiconductor substrate 11, and a silicon nitride film is formed inside the trench 102, and the silicon nitride film on the bottom surface 104 of the trench 102-1 is removed by etching back. Fig.19As shown in the second row from the top, a silicon nitride film 112 is formed on the side surface 103 of the trench 102 .

[0156] In the forty-third step, the trench 102 is further excavated downward to form a bottom surface 106 by etching the semiconductor substrate 11, a silicon oxide film is formed on the excavated portion, and the silicon oxide film on the bottom surface 106 is removed by etching back. Fig.19 As shown in the third row from the top, a hard mask 113 is formed in a region within the trench 102 where the silicon nitride film 112 is not formed.

[0157] In the forty-fourth step, the bottom surface 106 of the trench 102 is further dug downward by etching the semiconductor substrate 11, and the silicon nitride film 112 is washed away. Fig. 20 As shown in the first row from the top, the semiconductor substrate 11 is exposed on a portion of a middle section of the side surface 103 of the trench 102 and on a tip portion and a bottom surface 106 of the side surface 103 of the trench 102 .

[0158] In the forty-fifth step, the semiconductor substrate 11 is alkali etched, and the semiconductor substrate 11 exposed in the middle section and at the tip of the trench 102 is selectively etched in the silicon plane orientation. Through this operation, a protrusion 109 is formed in the middle section of the trench 102, and a protrusion 107 is formed at the tip of the trench 102.

[0159] Thereafter, the element separation portion 31 including two protrusions 33 is formed by burying a desired material such as metal in the groove 102. Of course, by repeating similar steps, the element separation portion 31 including three or more protrusions 33 can be formed.

[0160] refer to Fig.21 , a sixth manufacturing method will be described. For example, the sixth manufacturing method is a manufacturing method of manufacturing the element separation parts 31 including the protrusions 33 at different depths, respectively.

[0161] In the fifty-first step, a silicon oxide film is formed on the back surface of the semiconductor substrate 11 to form a hard mask 101, and the semiconductor substrate 11 is etched, thereby processing the trenches 102-1 and 102-2. Subsequently, a silicon oxide film is formed inside the trenches 102-1 and 102-2, and the silicon oxide film on the bottom surface 104-1 of the trench 102-1 and the bottom surface 104-2 of the trench 102-2 is removed by etching back. Through this operation, a side wall 105-1 is formed on the side surface 103-1 of the trench 102-1, and a side wall 105-2 is formed on the side surface 103-2 of the trench 102-2.

[0162] Then, by etching the semiconductor substrate 11, the bottom surface 104-1 of the trench 102-1 is dug out, and the bottom surface 104-2 of the trench 102-2 is dug out, and silicon nitride films are formed inside the trenches 102-1 and 102-2. At this time, in the trench 102-1, the silicon nitride film 112 is formed on the side surface 103-1, and in the trench 102-2, the silicon nitride film 114 is formed so as to be buried inside the trench 102-2. In addition, as Fig.21 As shown in the first row from the top, resist 115 is applied to the side of trench 102-2.

[0163] In the fifty-second step, after removing the resist 115, the bottom surface 104-1 of the trench 102-1 is further excavated downward by etching the semiconductor substrate 11. Then, a silicon oxide film is formed inside the trench 102-1 by chemical vapor deposition (CVD), and the silicon oxide film on the bottom surface 104-1 of the trench 102-1 is removed by etching back. By this operation, as shown in FIG. Fig.21 As shown in the second row from the top, a silicon oxide film 116 is formed.

[0164] In the fifty-third step, after the trench 102-1 is dug out to form the bottom surface 106-1 by etching the semiconductor substrate 11, the silicon nitride film 114 is washed away. Fig.21 As shown in the third row from the top, a trench 102-1 having a deep bottom surface 106-1 and a trench 102-2 having a shallow bottom surface 104-2 are formed.

[0165] In the fifty-fourth step, the semiconductor substrate 11 is alkali-etched, and the semiconductor substrate 11 exposed at the tip of the side surface 103-1 and the bottom surface 106-1 in the groove 102-1 is etched selectively in the silicon plane orientation to form the protrusion 107-1. Similarly, the semiconductor substrate 11 exposed at the tip of the side surface 103-2 and the bottom surface 106-2 in the groove 102-2 is etched selectively in the silicon plane orientation to form the protrusion 107-2.

[0166] That is, Fig.21 As shown in the fourth row from the top, the trench 102-1 having the protrusion 107-1 formed in the deep region and the trench 102-2 having the protrusion 107-2 formed in the shallow region can be manufactured separately.

[0167] Thereafter, by removing the silicon nitride film and the silicon oxide film and burying a desired material such as metal in the trenches 102-1 and 102-2, element separation portions 31-1 and 31-2 including protrusions 33-1 and 33-2 at different depths are formed, respectively.

[0168] Note that the steps for forming silicon nitride and silicon oxide may be reversed. If etching selectivity during rinsing can be ensured, other film type combinations may be selected.

[0169] refer to Fig. 22 , a seventh manufacturing method will be described. For example, the seventh manufacturing method is a manufacturing method of the element separation portion 31 including the protrusion 33 formed by isotropic etching using an acidic etching chemical solution.

[0170] In the sixty-first step, if Fig. 22 As shown in the first row from the top, a silicon oxide film is formed on the back surface of the semiconductor substrate 11 to form a hard mask 101, and the semiconductor substrate 11 is etched, thereby processing the trench 102.

[0171] In step sixty-second, if Fig. 22 As shown in the second row from the top, a sidewall film 105 is formed on the side 103 of the trench 102. For example, the sidewall 105 is formed by forming a silicon nitride film on the entire inner surface of the trench 102 and then etching back the bottom surface portion of the trench 102 to remove the silicon nitride film.

[0172] In the sixty-third step, if Fig. 22 As shown in the third row from the top, isotropic etching is performed on the semiconductor substrate 11 using an acidic chemical solution to form a bottom surface 110 extending substantially in a spherical shape at the bottom of the trench 102.

[0173] In step sixty-four, if Fig. 22 As shown in the fourth row from the top, the silicon nitride film is removed.

[0174] Thereafter, by burying a desired material such as metal in the trench 102 , the element separation portion 31 including the protrusion 33 formed by isotropic etching is formed.

[0175] refer to Fig.23 , an eighth manufacturing method will be described. For example, the eighth manufacturing method is a manufacturing method of the element separation portion 31 including the protrusion 33 having a different type of material buried.

[0176] First, by executing the reference Fig.15 The first to fourth steps described form the protrusions 107 of the groove 102 in a rhombus shape extending beyond the side surface 103 .

[0177] Thereafter, in the seventy-first step, if Fig.23 As shown in the first row from the top, tungsten 121 is buried in the trench 102.

[0178] In the seventy-second step, tungsten 121 in the trench 102 except for the protrusion is removed by performing etching back, so that tungsten 122 remains in the protrusion protruding in the side direction from the side surface 103 in the trench 102. Fig.23 As shown in the second row from the top, it is assumed that tungsten 122 is buried only in the protruding portion of the trench 102 .

[0179] In the seventy-third step, if Fig.23 As shown in the third row from the top, aluminum 123 is buried in the groove 102, and the semiconductor substrate 11 is flattened by chemical mechanical polishing (CMP) and dry etching. Through this operation, the element separation portion 31 is formed, in which tungsten 122 is buried in the protrusion of the protrusion 33, and aluminum 123 is buried in the portion other than the protrusion of the protrusion 33.

[0180] Here, the tungsten 122 embedded in the protrusion of the protrusion 33 is a material that absorbs light relatively more easily than the aluminum 123 embedded in the portion other than the protrusion in the groove 102 (hereinafter referred to as a high absorption material). That is, in the protrusion of the protrusion 33, a high absorption material having a higher absorption coefficient than the absorption coefficient of the material embedded in the portion other than the protrusion in the groove 102 is embedded. In addition, the aluminum 123 embedded in the portion other than the protrusion of the protrusion 33 in the groove 102 is a material that reflects light more easily than the tungsten 122 embedded in the protrusion of the protrusion 33 (hereinafter referred to as a high reflection material). That is, in the portion other than the protrusion of the protrusion 33 in the groove 102, a high reflection material having a higher reflectivity than the reflectivity of the material embedded in the protrusion of the protrusion 33 is embedded.

[0181] For example, it is known that reflected light generated at a deeper depth of the element separation portion 31 easily causes color mixing with the adjacent pixel 52. Therefore, by embedding tungsten 122, which is a highly absorbing material, in the protruding portion of the protruding portion 33, and by embedding aluminum 123, which is a highly reflecting material, in the protruding portion 33 other than the protruding portion, it is possible to suppress color mixing with the adjacent pixel 52. That is, by embedding tungsten 122 having a lower light reflectivity and a higher absorption coefficient in the protruding portion of the protruding portion 33 than the aluminum 123 embedded in the portion other than the protruding portion of the protruding portion 33 in the groove 102, it is possible to suppress color mixing with the adjacent pixel 52.

[0182] Note that the material embedded in the protrusion of the protrusion 33 needs to have a relatively lower reflectivity than the material of the portion other than the protrusion of the protrusion 33 embedded in the groove 102, and is not limited to the combination of tungsten 122 and aluminum 123 as described above. Specifically, as a high-reflection material, in addition to aluminum, silver, gold, copper, cobalt, etc. can be used. As a high-absorption material, in addition to tungsten, tantalum (tantalum nitride), titanium (titanium nitride), chromium, molybdenum, nickel, platinum, etc. can be used.

[0183] <Configuration Example of Electronic Equipment>

[0184] The imaging element 51 as described above can be applied to various electronic devices, for example, an imaging system such as a digital camera or a digital video camera, a mobile phone having an imaging function, or other devices having an imaging function.

[0185] Fig.24 is a block diagram showing a configuration example of an imaging apparatus mounted on an electronic device.

[0186] like Fig.24 As shown, the imaging apparatus 201 includes an optical system 202, an imaging element 203, a signal processing circuit 204, a monitor 205, and a memory 206, and can capture still images and moving images.

[0187] The optical system 202 includes one or more lenses, guides image light (incident light) from a subject to the imaging element 203 , and forms an image on a light receiving surface of the imaging element 203 (sensor unit).

[0188] As the imaging element 203, the above-described imaging element 51 is applied. Electrons are stored in the imaging element 203 for a certain time according to an image formed on the light receiving surface via the optical system 202. Then, a signal corresponding to the electrons stored in the imaging element 203 is supplied to the signal processing circuit 204.

[0189] The signal processing circuit 204 performs various types of signal processing on the pixel signal output from the imaging element 203. An image (image data) obtained by the signal processing by the signal processing circuit 204 is supplied to the monitor 205 for display or supplied to the memory 206 for storage (recording).

[0190] The image pickup apparatus 201 configured in this manner can capture a higher quality image with suppressed crosstalk, for example, by applying the above-described image pickup element 51 .

[0191] <Examples of using image sensors>

[0192] Fig.25 The diagram shows a usage example of the above-mentioned image sensor (imaging element).

[0193] The above-mentioned image sensors can be used to sense light in various situations, for example, as described below, to sense visible light, infrared light, ultraviolet light, X-rays, etc.

[0194] · Devices for capturing images for viewing, such as digital cameras and mobile devices with camera functions.

[0195] Equipment for transportation, such as on-board sensors that capture the front, rear, surroundings, and interior of a car, surveillance cameras that monitor moving vehicles and roads, and distance sensors that measure the distance between vehicles for safe driving (such as automatic stopping and recognition of the driver's condition, etc.).

[0196] Devices for home appliances such as TVs, refrigerators, and air conditioners to capture user gestures and operate the device based on the gestures.

[0197] Equipment used in medical and health care, such as endoscopes and equipment for angiography by receiving infrared rays.

[0198] ・Equipment for security, such as surveillance cameras for crime prevention and cameras for personnel authentication.

[0199] Equipment used for beauty treatments, such as skin measurement equipment for capturing skin images and microscopes for capturing scalp images.

[0200] Equipment used for sports, such as action cameras and wearable cameras in sports applications.

[0201] Equipment used in agriculture, such as cameras used to monitor the condition of fields and crops.

[0202] The Si{111} substrate in the present disclosure is a substrate or wafer including a silicon single crystal and having a crystal plane represented as {111} in Miller index notation. The Si{111} substrate in the present disclosure also includes a substrate or wafer whose crystal orientation deviates by several degrees, for example, a few degrees from the {111} plane in the nearest

[110] direction. In addition, it also includes a substrate or wafer obtained by growing a silicon single crystal on a part or the entire surface of a substrate or wafer by epitaxy or the like.

[0203] In addition, in the symbols of the present disclosure, the {111} plane is a general term for the (111) plane, (-111) plane, (1-11) plane, (11-1) plane, (-1-11) plane, (-11-1) plane, (1-1-1) plane, and (-1-1-1) plane, which are crystal planes that are symmetric to each other. Therefore, the description of the Si{111} substrate in the specification of the present disclosure, etc. can be understood as, for example, a Si(1-11) substrate. Here, the bar symbol representing the negative index of the Miller index is replaced by a minus sign.

[0204] In addition, in this embodiment <110> Direction is a general term for

[110] direction,

[101] direction,

[011] direction, [-110] direction, [1-10] direction, [-101] direction, [10-1] direction, [0-11] direction, [01-1] direction, [-1-10] direction, [-10-1] direction and [0-1-1] direction, which are crystal plane directions that are equivalent to each other in symmetry and can be understood as any one. However, the present disclosure performs etching in a direction orthogonal to the plane formed by the element and in a direction further orthogonal to the direction orthogonal to the plane formed by the element (i.e., a direction parallel to the plane formed by the element).

[0205] Table 1 shows the <111> The specific combination of the plane and direction in which etching is performed, the {111} plane is the crystal plane of the Si{111} substrate in this embodiment.

[0206] Table 1

[0207]

[0208] As shown in Table 1, the {111} plane and <110> There are 96 (=8×12) combinations of directions. <110> The direction is limited to the direction orthogonal to the {111} plane as the element formation plane and the direction parallel to the element formation plane. That is, the combination of the element formation plane on the Si{111} substrate of the present disclosure and the direction of etching on the Si{111} substrate is selected from any of the combinations indicated by circles in Table 1.

[0209] In addition, the above embodiment shows the case where etching is performed in the X-axis direction by using a Si{111} substrate and etching is not performed in the Y-axis direction and the Z-axis direction. However, the present disclosure is not limited to this case, and only requires that the etching progress orientation is in both the X-axis direction and the Y-axis direction, or in either the X-axis direction or the Y-axis direction. In addition, as Fig. 27 As shown, the Si{111} substrate includes, for example, treating the surface of the substrate so that it is <112> When the deflection angle is less than 19.47°, even when using a substrate with a deflection angle, it is necessary to maintain <110> The etching rate in the direction (i.e., in the direction with a Si back bond) is higher than that in the <111> The etching rate in the direction (i.e., in the direction with three Si back bonds) is sufficiently high. As the deflection angle increases, the number of steps increases and the density of micro-steps increases, so it is preferably 5° or less. Note that Fig. 27The example mentioned that the substrate surface is <112> In the case of a deflection angle in the direction, however, <110> It does not matter if there is a deflection angle in the direction, and the direction of the deflection angle does not matter. In addition, the Si plane orientation can be analyzed by using X-ray diffraction, electron beam diffraction, electron beam backscattering diffraction, etc. Since the number of Si back bonds is determined by the crystal structure of Si, the number of back bonds can also be analyzed by analyzing the Si plane orientation.

[0210] <Example of combination of structures>

[0211] Note that the present technology may also have the following configurations. (1)

[0213] A camera element, comprising:

[0214] a semiconductor substrate in which a photoelectric conversion unit for photoelectrically converting emitted light is formed;

[0215] a groove portion provided between the plurality of the photoelectric conversion portions from the light receiving surface side of the semiconductor substrate; and

[0216] A protrusion is provided with at least an inclined surface inclined with respect to a side surface of the groove portion so as to widen an interval of the groove portion in a part of the groove portion. (2)

[0218] The imaging device according to (1) above, wherein:

[0219] The protruding portion is constituted by the inclined surface oriented along a predetermined plane of a crystal constituting the semiconductor substrate. (3)

[0221] The imaging element according to (1) or (2) above, wherein:

[0222] The protrusion is provided at the tip of the groove portion. (4)

[0224] The imaging device according to any one of (1) to (3) above, wherein:

[0225] The protrusion is provided at an intermediate section from the light receiving surface of the semiconductor substrate to the tip of the groove portion. (5)

[0227] The imaging device according to any one of (1) to (4) above, wherein:

[0228] The protrusions are provided at a plurality of locations from a light receiving surface of the semiconductor substrate to a tip end of the groove portion. (6)

[0230] The imaging device according to any one of (1) to (5) above, wherein:

[0231] A material that prevents light transmission is buried in the groove portion and the protrusion portion. (7)

[0233] The imaging element according to (6) above,

[0234] The first material buried in the protrusion of the protruding portion that protrudes laterally from the side surface of the groove portion and the second material buried in the groove portion outside the protrusion have different properties. (8)

[0236] The imaging element according to (7) above, wherein:

[0237] The first material has a higher light absorption coefficient than the second material, and

[0238] The second material has a higher light reflectivity than the first material. (9)

[0240] The imaging device according to any one of (1) to (8) above, wherein:

[0241] The semiconductor substrate is a Si{111} substrate having a thickness direction defined as a first direction and having a first crystal plane represented by a plane index {111} extending along a horizontal plane orthogonal to the first direction, and

[0242] The inclined surface of the protrusion includes a surface along a crystal plane of the Si{111} substrate, the crystal plane of the Si{111} substrate being inclined with respect to the first direction and represented by a plane index {111}. (10)

[0244] A camera element, comprising:

[0245] A Si substrate, a thickness direction of which is defined as a first direction and extends along a horizontal plane orthogonal to the first direction;

[0246] a photoelectric conversion unit that is provided in the Si substrate and generates charges corresponding to the amount of received light by photoelectric conversion; and

[0247] a protrusion having at least an inclined surface inclined with respect to a side surface of the groove portion so as to widen the interval of the groove portion in a part of the groove portion provided between the plurality of the photoelectric conversion portions,

[0248] The protrusion includes a plane along a second crystal plane that is inclined relative to the first direction and has three Si back bonds. (11)

[0250] A manufacturing method comprising:

[0251] A groove portion is dug out using a manufacturing apparatus for manufacturing an image pickup element, the groove portion being provided between a plurality of photoelectric conversion portions from a light receiving surface side of a semiconductor substrate having a photoelectric conversion portion for photoelectrically converting emitted light formed thereon, and

[0252] A protrusion is formed, the protrusion being provided with at least an inclined surface inclined with respect to a side surface of the groove portion so as to widen an interval of the groove portion in a part of the groove portion. (12)

[0254] An electronic device including an imaging element, the imaging element comprising:

[0255] a semiconductor substrate in which a photoelectric conversion portion for photoelectrically converting emitted light is formed;

[0256] a groove portion provided between the plurality of the photoelectric conversion portions from the light receiving surface side of the semiconductor substrate; and

[0257] A protrusion is provided with at least an inclined surface inclined with respect to a side surface of the groove portion so as to widen an interval of the groove portion in a part of the groove portion. (13)

[0259] The manufacturing method according to the above (11), further comprising:

[0260] The protrusions are formed by silicon plane-oriented selective etching using an alkaline chemical solution.

[0261] Note that the present embodiment is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present disclosure. In addition, the effects described in this specification are merely illustrative and not restrictive, and other effects can be produced.

[0262] Reference numerals list

[0263] 11 Semiconductor substrate

[0264] 12. Planarization film

[0265] 13 Color filter layer

[0266] 14 On-chip lens layer

[0267] 15 Wiring Layer

[0268] 21 Component separation

[0269] 22 Groove side

[0270] 23 Flat part

[0271] 24, 25 shading part

[0272] 31 Component separation unit

[0273] 32 Groove side

[0274] 33 Protrusion

[0275] 34, 35 light shielding part

[0276] 51 Camera Components

[0277] 52 pixels

[0278] 53 Color Filters

[0279] 54 Microlens

[0280] 55 Inner lens

[0281] 61 blackout wall

[0282] 62 Charge storage unit

[0283] 63 Opening

[0284] 64 FD Department

Claims

1. An imaging element, comprising: a semiconductor substrate in which a photoelectric conversion portion for photoelectrically converting emitted light is formed; a charge storage unit, which is arranged below the photoelectric conversion unit; a light shielding wall, which is disposed between the photoelectric conversion unit and the charge storage unit and extends in a horizontal direction so that the charge storage unit is shielded from light; a groove portion provided between the plurality of the photoelectric conversion portions from the light receiving surface side of the semiconductor substrate; as well as a protrusion provided with an inclined surface inclined with respect to a side surface of the groove portion in a middle section from the light receiving surface of the semiconductor substrate to the tip of the groove portion so as to widen the interval of the groove portion in a part of the groove portion, The light shielding wall is provided with an opening, and the charge from the photoelectric conversion unit is transmitted to the charge storage unit through the opening. The horizontal dimension of the protrusion is larger than the opening of the light shielding wall, and In a region where the opening of the light-shielding wall is provided, adjacent photoelectric conversion units are separated by the groove portion including the protrusion, and in a region other than the opening of the light-shielding wall, adjacent photoelectric conversion units are separated by the groove portion not including the protrusion.

2. The imaging element according to claim 1, wherein: The protruding portion is constituted by the inclined surface oriented along a predetermined plane of a crystal constituting the semiconductor substrate.

3. The imaging element according to claim 1 or 2, wherein: A material that prevents light transmission is buried in the groove portion and the protrusion portion.

4. The imaging element according to claim 3, wherein: The first material buried in the protrusion of the protruding portion that protrudes laterally from the side surface of the groove portion and the second material buried in the groove portion outside the protrusion have different properties.

5. The imaging element according to claim 4, wherein: The first material has a higher light absorption coefficient than the second material, and The second material has a higher light reflectivity than the first material.

6. The imaging element according to claim 1 or 2, wherein: The semiconductor substrate is a Si{111} substrate having a thickness direction defined as a first direction and having a first crystal plane represented by a plane index {111} extending along a horizontal plane orthogonal to the first direction, and The inclined surface of the protrusion includes a surface along a crystal plane of the Si{111} substrate, the crystal plane of the Si{111} substrate being inclined with respect to the first direction and represented by a plane index {111}.

7. An imaging element, comprising: A Si substrate, a thickness direction of which is defined as a first direction and extends along a horizontal plane orthogonal to the first direction; a photoelectric conversion unit which is provided in the Si substrate and generates charges corresponding to the amount of received light by photoelectric conversion; a charge storage unit, which is arranged below the photoelectric conversion unit; a light shielding wall, which is disposed between the photoelectric conversion unit and the charge storage unit and extends in a horizontal direction so that the charge storage unit is shielded from light; a groove portion provided between the plurality of photoelectric conversion portions from the light receiving surface side of the Si substrate; as well as a protrusion provided with an inclined surface inclined with respect to a side surface of the groove portion in a middle section from the light receiving surface of the Si substrate to the tip of the groove portion so as to widen the interval of the groove portion in a part of the groove portion, wherein the protrusion includes a plane along a second crystal plane inclined relative to the first direction and having three Si back bonds, The light shielding wall is provided with an opening, and the charge from the photoelectric conversion unit is transmitted to the charge storage unit through the opening. The horizontal dimension of the protrusion is larger than the opening of the light shielding wall, and In a region where the opening of the light-shielding wall is provided, adjacent photoelectric conversion units are separated by the groove portion including the protrusion, and in a region other than the opening of the light-shielding wall, adjacent photoelectric conversion units are separated by the groove portion not including the protrusion.

8. A manufacturing method, comprising: digging a groove portion provided between a plurality of photoelectric conversion portions that photoelectrically convert emitted light from a light receiving surface side of a semiconductor substrate on which a photoelectric conversion portion that photoelectrically converts emitted light is formed using a manufacturing apparatus for manufacturing an image pickup element; forming a charge storage unit, wherein the charge storage unit is disposed below the photoelectric conversion unit; forming a light shielding wall, the light shielding wall being disposed between the photoelectric conversion unit and the charge storage unit and extending in a horizontal direction so that the charge storage unit is shielded from light; and forming a protrusion provided with an inclined surface inclined with respect to a side surface of the groove portion in a middle section from the light receiving surface of the semiconductor substrate to the tip of the groove portion so as to widen the interval of the groove portion in a part of the groove portion, The light shielding wall is provided with an opening, and the charge from the photoelectric conversion unit is transmitted to the charge storage unit through the opening. The horizontal dimension of the protrusion is larger than the opening of the light shielding wall, and In a region where the opening of the light-shielding wall is provided, adjacent photoelectric conversion units are separated by the groove portion including the protrusion, and in a region other than the opening of the light-shielding wall, adjacent photoelectric conversion units are separated by the groove portion not including the protrusion. 9 . An electronic device comprising an imaging element, wherein the imaging element is the imaging element according to claim 1 .

Images