Imaging element and imaging device

Abstract

The imaging element includes: a plurality of photoelectric conversion element groups, each of which includes a plurality of photoelectric conversion elements and is arranged in a two-dimensional direction; a transparent layer that faces the plurality of photoelectric conversion element groups and extends with the two-dimensional direction as the plane direction; and a plurality of structural body groups that are arranged in the plane direction of the transparent layer corresponding to the plurality of photoelectric conversion element groups on or within the transparent layer. Each of the plurality of structural body groups includes a plurality of structural bodies arranged in the same pattern, and each of the plurality of structural body groups is configured to split incident light for the photoelectric conversion elements of the corresponding photoelectric conversion element group. In a plan view, the relative position between the corresponding photoelectric conversion element group and the structural body group is different according to the position in two dimensions.

Description

Technical Field

[0001] The present disclosure relates to an imaging element and an imaging device. Background Art

[0002] In an imaging device, it is known that the incident angles of light are different between the central portion and the outer peripheral portion of an imaging element (for example, see Patent Document 1).

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2006-528424 Summary of the Invention

[0006] Problems to be Solved by the Invention

[0007] If the incident angle is deviated, light cannot be efficiently guided to the conversion element, and there is a problem of reduced light reception efficiency.

[0008] According to one aspect of the present disclosure, the light reception efficiency can be improved.

[0009] Means for Solving the Problems

[0010] An imaging element according to one aspect of the present disclosure is characterized by including: a plurality of photoelectric conversion element groups each including a plurality of photoelectric conversion elements, the plurality of photoelectric conversion element groups being arranged in a two-dimensional direction; a transparent layer facing the plurality of photoelectric conversion element groups and extending in a two-dimensional direction as a plane direction; and a plurality of structure groups arranged in the plane direction of the transparent layer corresponding to the plurality of photoelectric conversion element groups on or in the transparent layer, each of the plurality of structure groups including a plurality of structures arranged in the same pattern, and each of the plurality of structure groups being configured to split incident light for the photoelectric conversion elements of the corresponding photoelectric conversion element group, and in a plan view, the relative positions between the corresponding photoelectric conversion element group and the structure group are different according to the positions in two dimensions.

[0011] An imaging device according to one aspect of the present disclosure is characterized by including the above-described imaging element and a signal processing unit that generates an image signal based on an electrical signal obtained from the imaging element.

[0012] Effects of the Invention

[0013] According to the present disclosure, the light reception efficiency can be improved. Brief Description of the Drawings

[0014] Figure 1 It is a diagram showing an example of a schematic configuration of the imaging element and the imaging device according to the embodiment.

[0015] Figure 2 This is a diagram showing an example of the schematic structure of an imaging element.

[0016] Figure 3 This is a diagram showing an example of the schematic structure of the central part of an imaging element.

[0017] Figure 4 This is a diagram showing an example of the schematic structure of the central part of an imaging element.

[0018] Figure 5 This is a diagram showing an example of the schematic structure of a structure body.

[0019] Figure 6 This is a diagram showing an example of the schematic structure of a structure body.

[0020] Figure 7 This is a diagram showing an example of the schematic structure of the outer peripheral part of an imaging element.

[0021] Figure 8 This is a diagram showing an example of the schematic structure of the outer peripheral part of an imaging element.

[0022] Figure 9 This is a diagram showing a comparative example.

[0023] Figure 10 This is a diagram showing an example of the schematic structure of the middle part of an imaging element.

[0024] Figure 11 This is a diagram showing an example of the schematic structure of the middle part of an imaging element.

[0025] Figure 12 This is a diagram showing an example of the schematic structure of the central part of an imaging element.

[0026] Figure 13 This is a diagram showing an example of the schematic structure of the outer peripheral part of an imaging element.

[0027] Figure 14 This is a diagram showing an example of the schematic structure of the middle part of an imaging element.

[0028] Figure 15 This is a diagram showing an example of the schematic structure of the outer peripheral part of an imaging element.

[0029] Figure 16 This is a diagram showing an example of the schematic structure of the middle part of an imaging element.

[0030] Figure 17 This is a diagram showing an example of the schematic structure of an imaging element.

[0031] Figure 18 This is a diagram showing an example of the schematic structure of a specific PD part of an imaging element. Detailed implementation manners

[0032] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The shapes, sizes, positional relationships, etc. shown in the drawings are merely schematic, and the present invention is not limited by them. The same parts are denoted by the same reference numerals, and repeated descriptions are omitted.

[0033] Figure 1 FIG. is an example showing a schematic structure of an imaging element and an imaging device according to an embodiment. The imaging device 10 captures an object 1 using light from the object 1 (subject) as incident light. In this example, the object 1 is illustrated as a hollow arrow. The incident light enters the imaging element 12 via the lens optical system 11. The signal processing unit 13 processes the electrical signal from the imaging element 12 to generate an image signal. As Figure 1 shown, the direction of the light incident on the imaging element 12 (the incident angle toward the imaging element 12) varies according to the position of the imaging element 12.

[0034] Figure 2 FIG. is an example showing a schematic structure of the imaging element. In the figure, an XYZ coordinate system is shown, and the traveling direction of the incident light is schematically shown by an arrow. The Z-axis direction corresponds to the stacking direction of the PD layer 4 and the transparent layer 5 described later. The XY plane direction corresponds to the plane direction of these layers. Hereinafter, "top view" means observing along the Z-axis direction (e.g., along the negative Z-axis direction), and "side view" means observing along the X-axis direction or the Y-axis direction (e.g., along the positive Y-axis direction). Figure 2 FIG. is a cross-sectional view showing an example of the schematic structure of the imaging element 12 in a side view.

[0035] The imaging element 12 includes a wiring layer 3, a PD (photodiode) layer 4, and a transparent layer 5.

[0036] If the description starts from the PD layer 4 in the wiring layer 3 and the PD layer 4, the PD layer 4 includes a plurality of PD groups 40 arranged in the plane direction of the layer (which can also be said to be arranged in a two-dimensional direction (in a two-dimensional shape)). Each PD group 40 includes a plurality of PDs arranged in the plane direction of the layer. The plurality of PDs are formed on the semiconductor substrate 100. The charges generated in each PD are converted into electrical signals that are the basis of pixel signals by transistors (not shown) and are output to the outside of the pixel 2 via the wiring layer 3. A plurality of wirings corresponding to each PD are illustrated as wirings 30.

[0037] The transparent layer 5 is an optical element that splits incident light for the photoelectric conversion elements facing multiple PD groups 40. An example of the optical element is a metasurface. Hereinafter, the case where the transparent layer 5 is a metasurface will be described. A metasurface is an element composed of multiple microstructures with widths below the wavelength of light, and it can be either a two-dimensional structure or a three-dimensional structure. By using a metasurface for the optical element, there is an effect that the phase and light intensity can be controlled according to the characteristics of light (wavelength / polarization / angle of incidence) only by changing the parameters of the microstructures. In the case of being configured as a three-dimensional structure, there is an effect of improving the above-mentioned design freedom. The transparent layer 5 is disposed opposite to the PD layer 4. In this example, the transparent layer 5 is disposed on the upper surface (the surface on the positive Z-axis side) of the PD layer 4. The transparent layer 5 extends with the surface direction of the PD layer 4 as the surface direction of the layer. The transparent layer 5 includes multiple structure groups 50 arranged in the surface direction of the layer. In Figure 2 In the example shown, the multiple structure groups 50 are disposed within the transparent layer 5. However, the multiple structure groups 50 can also be disposed on the transparent layer 5. The multiple structure groups 50 can be disposed on the lower surface of the transparent substrate. In this case, the transparent layer 5 is an air layer. The structures constituting the multiple structure groups 50 are microstructures having dimensions on the order of or smaller than the wavelength (nanoscale) of the incident light.

[0038] The portion of the transparent layer 5 where no structure is provided can have a refractive index lower than that of the structure. An example of the material of such a transparent layer 5 is SiO2, etc. The transparent layer 5 can also be a void. In this case, the refractive index of the transparent layer 5 is the refractive index of air.

[0039] As previously referred to Figure 1 As described, the angle of the incident light toward the imaging element 12 varies depending on the position on the imaging element 12. In Figure 2 In the example shown, the incident angle of the light toward the transparent layer 5 varies depending on the position in two dimensions (on the XY plane). In the imaging element 12, the incident angle of the central portion in two dimensions (hereinafter, sometimes simply referred to as the "central portion") is 0° in this example. Therefore, the light is incident perpendicularly to the transparent layer 5. In the imaging element 12, the incident angle of the peripheral portion in two dimensions (hereinafter, sometimes simply referred to as the "peripheral portion") deviates from the incident angle of the central portion. The deviation of the incident angle increases as it goes from the central portion toward the peripheral portion.

[0040] Figure 3 And Figure 4 is a diagram showing an example of the schematic structure of the central portion of the imaging element. Figure 3 is a cross-sectional view showing an example of the schematic structure of the imaging element 12 in side view. Figure 4This is a diagram showing an example of the schematic structure of the imaging element 12 when viewed from above. In addition, since the PD group 40 is located on the lower side (negative Z-axis direction side) of the structure group 50, the PD group 40 is shown by a dashed line in Figure 4 .

[0041] As the multiple diodes included in the PD group 40, PD41, PD42, and PD43 are illustrated. PD41, PD42, and PD43 are arranged in sequence in the plane direction of the PD layer 4 (in this example, the X-axis direction). It is assumed that PD41, PD42, and PD43 are incident with light in bands corresponding to the respective colors. For example, PD41, PD42, and PD43 correspond to red (R), green (G), and blue (B).

[0042] As the multiple structures included in the structure group 50, the structure 51, the structure 52, and the structure 53 are illustrated. The structure 51, the structure 52, and the structure 53 are each a multiple of structures configured in the same pattern. The so-called same pattern means, for example, that the sizes (widths) and intervals of the respective structures in the plane direction of the transparent layer 5 are the same. The sizes (heights) of the respective structures in the stacking direction may also be the same. The structure 51, the structure 52, and the structure 53 are configured to split the incident light toward the PD41, PD42, and PD43 in the corresponding PD group 40, respectively. More specifically, the structure 51, the structure 52, and the structure 53 are configured to split the incident light toward the centers of PD41, PD42, and PD43, respectively. The incident light is, for example, split into light in bands corresponding to the respective RGB colors as described above and reaches the corresponding PD41, PD42, and 43. In addition, in Figure 3 and Figure 4 the example shown, the center of the structure group 50 is located on the center of the PD group 40 (on PD42 in this example).

[0043] Refer to Figure 5 and Figure 6 to explain the light splitting principle of the structure 51, the structure 52, and the structure 53. Hereinafter, the structure 51 will be taken as an example for explanation. The same explanation can also be made for the structure 52 and the structure 53.

[0044] Figure 5 and Figure 6 are diagrams showing examples of the schematic structure of the structure. An example of the top view of the structure 51 is shown in Figure 5 . An example of the side view of the structure 51 is shown in Figure 6 .

[0045] In this example, the structure 51 is a fine columnar structure. The structure 51 is formed of a material such as SiN having a refractive index n1 higher than the refractive index n0 of the other parts of the transparent layer 5, and the thickness h (length in the Z-axis direction) of the structure is constant.

[0046] The bottom surface and the upper surface of the structure 51 are square. The structure 51 functions as an optical waveguide that confines light in the structure according to the above-mentioned refractive index difference and propagates it. Therefore, when light is incident from the upper surface side, the light is strongly confined and propagated in the structure 51, and is emitted from the bottom surface side due to the optical phase delay effect determined by the effective refractive index n eff of the optical waveguide. Specifically, when the phase of the light that has propagated a length corresponding to the thickness of the transparent layer 5 is taken as a reference, if the wavelength of the light in a vacuum is set to λ, the optical phase delay amount φ based on the structure 51 is represented by φ = (n eff - n0) × 2πh / λ. Since this optical phase delay amount varies according to the wavelength λ, for light incident on the same structure 51, different optical phase delay amounts are given according to the wavelength band (color). Since the bottom surface and the upper surface of the structure 51 are square, the optical characteristics including the optical phase delay effect do not change even when the polarization direction is changed. It is known that n eff is a function of the structural dimensions, and takes values of n0 < n eff < n1. Therefore, by changing the width W of the structure 51, any optical phase delay amount can be set. By changing the refractive index of the structure 51, any optical phase delay amount can also be set. The structures 51 having different refractive indices can be made of materials having different refractive indices. The same applies to the structure 52 and the structure 53.

[0047] Refer to Figure 3 and Figure 4 simultaneously. The structure 51, the structure 52, and the structure 53 have different widths so as to give different optical phase delay distributions for each wavelength region to the light transmitted through the structure group 50 to change the wavefront of the light wave. Since the emission direction (propagation direction) of the light is determined by the wavefront, the light transmitted through the structure group 50 is spatially separated according to the colors (wavelength bands) corresponding to PD41, PD42, and PD43. In this way, the incident light is spectroscopically separated toward PD41, PD42, and PD43, respectively.

[0048] In multiple structural body groups 50, the structural bodies 51, 52, and 53 are all configured in the same pattern. Therefore, the relationship between the incident angle and the exit angle of light in each structural body group 50 is also the same. If the incident angle is different, the exit angle is also different. As described above, since the incident angle of the outer peripheral portion deviates from the incident angle of the central portion, the exit angle of the light emitted from the transparent layer 5 to the PD layer 4 also shifts. When the exit angle shifts, the light cannot be efficiently guided to the PDs 41, 42, and 43 in the corresponding PD group 40. Therefore, in the imaging element 12, the relative position between the PD group 40 and the structural body group 50 is set corresponding to the shift of the incident angle (which can also be said to be the exit angle caused by the shift of the incident angle).

[0049] Figure 7 and Figure 8 is a diagram showing an example of the schematic structure of the outer peripheral portion of the imaging element. Figure 7 is a cross-sectional view showing an example of the schematic structure of the imaging element 12 when viewed from the side. Figure 8 is a diagram showing an example of the schematic structure of the imaging element 12 when viewed from above.

[0050] In the outer peripheral portion, the incident angle of the light incident on the structural body group 50 deviates from the incident angle of the central portion ( Figure 3 ). Since the incident angle shifts, the exit angle of the light emitted from the structural body group 50 toward the PD group 40 also shifts. However, the relative position between the PD group 40 and the structural body group 50 also deviates from the relative position at the central portion ( Figure 3 and Figure 4 ). In this example, the position of the structural body group 50 relative to the PD group 40 shifts toward the PD41 side in the PD group 40. Specifically, the central position of the structural body group 50 is located above the PD41 side portion in the PD group 40 (above PD41 in this example). As the relative position between the PD group 40 and the structural body group 50 shifts, the direction (angle) of observing the PD group 40 from the structural body group 50 also shifts accordingly. The relative position between the PD group 40 and the structural body group 50 is set so that the shift in the direction (angle) of observing the PD group 40 from the structural body group 50 cancels out the above-mentioned shift in the exit angle. As a result, in the outer peripheral portion, the structural body group 50 also splits the incident light toward the centers of the PD41, PD42, and PD43 respectively.

[0051] In addition, assuming that the relative position between the PD group 40 and the structural body group 50 at the outer peripheral portion is the same as the relative position at the central portion, the light split by the structural body group 50 does not face the centers of the PD41, PD42, and PD43. Regarding this, refer to Figure 9 for an explanation.

[0052] Figure 9 This is a diagram showing a comparative example. In the illustrated imaging element 12E, the relative position between the PD group 40 and the structure group 50E is the same as the relative position at the central portion. The light split by the structures 51E, 52E, and 53E reaches positions deviated from the centers of the PDs 41, 42, and 43, where the degree of deviation from the centers of the PDs 41, 42, and 43 corresponds to the degree of deviation of the emission angle due to the deviation of the incident angle. As previously referred to Figure 7 and Figure 8 As described, this problem is reduced or eliminated by the imaging element 12 of the embodiment.

[0053] Figure 10 and Figure 11 This is a diagram showing an example of the schematic structure of the middle portion of the imaging element. The middle portion is the portion between the central portion and the outer peripheral portion. Figure 10 This is a cross-sectional view showing an example of the schematic structure of the imaging element 12 when viewed from the side. Figure 11 This is a diagram showing an example of the schematic structure of the imaging element 12 when viewed from above.

[0054] In the middle portion, the deviation of the incident angle is smaller than the deviation of the incident angle in the outer peripheral portion ( Figure 7 ). The deviation of the emission angle caused by the deviation of the incident angle is also smaller than the deviation of the emission angle in the outer peripheral portion. Therefore, the deviation of the relative position between the PD group 40 and the structure group 50 is also smaller than the deviation of the relative position in the outer peripheral portion. In the middle portion, the structure group 50 also splits the incident light toward the centers of the PDs 41, 42, and 43 respectively.

[0055] For example, as described above, in the imaging element 12, the relative position between the corresponding PD group 40 and the structure group 50 varies according to the two-dimensional (XY planar) position. More specifically, with the relative position between the PD group 40 and the structure group 50 at the central portion as a reference, the deviation of the relative position becomes larger as it moves toward the outer peripheral portion. Assuming that the relative position is the same at any position, as previously referred to Figure 9 As described, the light split by the structure group 50 reaches positions deviated from the centers of the PDs 41, 42, and 43. As a result, the light cannot be efficiently incident on the PDs 41, 42, and 43, and problems such as deterioration of light reception sensitivity may occur. In response to this, in the imaging element 12, by staggering the relative position between the corresponding PD group 40 and the structure group 50, the splitting direction based on the structure group 50 can be made closer to the centers of the PDs 41, 42, and 43. Therefore, the light reception efficiency can be improved.

[0056] Refer again toFigure 1 , the signal processing unit 13 of the imaging device 10 will be described. The signal processing unit 13 generates pixel signals based on the electrical signals obtained from the imaging element 12. To obtain the electrical signals, the signal processing unit 13 also controls the imaging element 12. The control of the imaging element 12 includes the exposure of the pixels 2 of the imaging element 12, the conversion of the charges accumulated in the PD layer 4 into electrical signals, the reading out of the electrical signals, etc.

[0057] As described above, one embodiment of the present disclosure has been described. However, the imaging element and the imaging device of the embodiment can be variously modified without departing from the gist of the embodiment. Some modification examples will be described.

[0058] In the above embodiment, a method of using the relative position between the PD group 40 and the structure group 50 to cope with the problem caused by the shift of the incident light has been described. Various other methods can also be used together with or instead of this method.

[0059] For example, it is also possible to make the incident angles of the light incident on the transparent layer 5 in the peripheral part and the middle part closer to the incident angle in the central part. For this, refer to Figures 12 to 16 for description.

[0060] Figure 12 is a diagram showing an example of the schematic structure of the central part of the imaging element. The illustrated imaging element 12A is different from the imaging element 12 ( Figure 3 etc.) in that it includes a transparent layer 5A instead of the transparent layer 5 and also includes a plurality of lenses 61. The transparent layer 5A includes a plurality of structure groups 50A.

[0061] Each of the plurality of lenses 61 is a microlens provided for each of the plurality of structure groups 50A. The lens 61 has a shape corresponding to the position in two dimensions. In this example, the lens 61 does not change the direction of the incident light. The structures 51A, 52A, and 53A in the structure group 50A are configured to split the light from the lens 61 toward the centers of the PDs 41, 42, and 43, respectively.

[0062] In the peripheral part and the middle part, the incident angles of the light incident on the structure group 50A deviate from the incident angle in the central part ( Figure 12 ). As examples of methods for reducing this deviation, two methods will be described. In the first method, the principle of shifting the position of the structure group relative to the PD group described above is also applied to the plurality of lenses 61. Refer to Figure 13 and Figure 14 for description of the first method.

[0063] Figure 13This is a diagram showing an example of the schematic structure of the outer peripheral portion of the imaging element. Compared with the central portion ( Figure 12 ), the relative positions between the plurality of lenses 61 and the structural body group 50 deviate from the relative positions at the central portion. In this example, the positions of the plurality of lenses 61 are shifted toward the PD41 side with respect to the structural body group 50A. The lenses 61 are configured to make the incident angle of the light toward the structural body group 50A close to the incident angle at the central portion. The structural bodies 51A, 52A, and 53A in the structural body group 50A are configured to split the light from the lens 62 toward the centers of the respective PD41, PD42, and PD43.

[0064] Figure 14 This is a diagram showing an example of the schematic structure of the middle portion of the imaging element. Compared with the central portion ( Figure 12 ), the relative positions between the plurality of lenses 61 and the structural body group 50 deviate from the relative positions at the central portion. This deviation is smaller than the deviation at the outer peripheral portion ( Figure 13 ). The lenses 61 are configured to make the incident angle of the light toward the structural body group 50A close to the incident angle at the central portion. The structural bodies 51A, 52A, and 53A in the structural body group 50A are configured to split the light from the lens 62 toward the centers of the respective PD41, PD42, and PD43.

[0065] The second method is a method of providing lenses having a shape corresponding to positions in two dimensions. In this regard, reference is made to Figure 15 and Figure 16 for explanation.

[0066] Figure 15 This is a diagram showing an example of the schematic structure of the outer peripheral portion of the imaging element. Compared with the central portion ( Figure 12 ), the imaging element 12A includes a plurality of lenses 62 instead of the plurality of lenses 61. Each of the plurality of lenses 62 is a microlens provided for each of the plurality of structural body groups 50A. The lenses 62 are configured to make the incident angle of the light toward the structural body group 50 close to the incident angle at the central portion. The lenses 62 have a shape corresponding to positions in two dimensions, and the lenses 62 have a shape deformed from the shape of the lens 61 ( Figure 12 ). The structural bodies 51A, 52A, and 53A in the structural body group 50A are configured to split the light from the lens 62 toward the centers of the respective PD41, PD42, and PD43.

[0067] Figure 16 This is a diagram showing an example of the schematic structure of the middle portion of the imaging element. Compared with the central portion ( Figure 12) In contrast, the imaging element 12A includes a plurality of lenses 63 instead of the plurality of lenses 61. Each lens 63 among the plurality of lenses 63 is a microlens provided for each structural body group 50A among the plurality of structural body groups 50A. The lens 63 is configured to make the incident angle of the light toward the structural body group 50 close to the incident angle of the central portion. The lens 63 has a shape corresponding to the position in two dimensions, and the lens 63 has a shape deformed from the shape of the lens 61 ( Figure 12 ) The degree of this deformation is smaller than the degree of deformation of the lens 62 ( Figure 15 ). The structural bodies 51A, 52A, and 53A in the structural body group 50A are configured to split the light from the lens 63 toward the centers of the PD41, PD42, and PD43, respectively.

[0068] As described above, as Figures 12 to 16 shown, by making the relative position between the corresponding plurality of lenses 61 and the structural body group 50 different according to the position in two dimensions, or by providing the lenses 61, 62, and 63 having shapes corresponding to the position in two dimensions, it is possible to make the incident angle of the light incident on the transparent layer 5 in the peripheral portion and the middle portion close to the incident angle of the central portion. Thus, for example, compared with the case of using only the plurality of structural body groups 50A, it is easier to split the light toward the centers of the PD41, PD42, and PD43 in the PD group 40. In addition, for example, if the incident angles of the peripheral portion and the middle portion can be made sufficiently close to the incident angle of the central portion only by the lens 61 or the like, the relative position between the corresponding structural body group 50A and the PD group 40 may not shift. This is because each structural body group 50A splits the light toward the centers of the PD41, PD42, and PD43, respectively.

[0069] For example, in order to suppress the reflection of the incident light to the PD, a reflection suppression layer may be provided. Regarding this, reference is made to Figure 17 and Figure 18 for description.

[0070] Figure 17 is a diagram showing an example of the schematic structure of the imaging element. The illustrated imaging element 12B is different from the imaging element 12 ( Figure 2 ) in that it further includes a reflection suppression layer 7.

[0071] The reflection suppression layer 7 is provided to cover the PD layer 4 and suppress the reflection of the light incident on the PD layer 4. In this example, the reflection suppression layer 7 is provided between the PD layer 4 and the transparent layer 5.

[0072] In Figure 17In the example shown, the reflection suppression layer 7 includes a plurality of diffraction gratings 70. The plurality of diffraction gratings 70 are periodically arranged in the plane direction of the reflection suppression layer 7. The plurality of diffraction gratings 70 have an effective refractive index with a size different from that of the refractive index of the PD layer 4. The effective refractive index is the value of the refractive index when it is assumed that the diffraction grating gives a hypothetical refractive index, and the reflection suppression layer 7 functions as a part (which may also be referred to as a material, component, etc.) having the effective refractive index. The method of achieving a desired effective refractive index by periodically arranging a plurality of diffraction gratings is well-known, and thus will not be described herein in detail. The effective refractive index is determined by the grating period (the arrangement interval of the diffraction gratings 70 in the XY plane direction), the grating height (the length of the diffraction gratings 70 in the Z-axis direction), etc. The grating period can be set to be less than the wavelength of the incident light. Examples of the material of the diffraction grating 70 are, for example, resins such as plastics, glass, etc.

[0073] The diffraction grating 70 has an effective refractive index with a size between the refractive index of the PD layer 4 and the refractive index of the portion located on the side opposite to the PD layer 4 across the diffraction grating 70. Since the PD layer 4 is formed on the semiconductor substrate 100, the refractive index of the PD layer 4 can be the same as the refractive index of the semiconductor substrate 100. The refractive index of the portion on the opposite side is the refractive index of the transparent layer 5 in this example. By the diffraction grating 70 having an effective refractive index with a size between these refractive indices, the reflection suppression layer 7 reduces the discontinuity between the refractive index of the PD layer 4 and the refractive index of the transparent layer 5, and suppresses the reflection of light incident on the PD layer 4.

[0074] As Figure 17 shown, by providing the reflection suppression layer 7, it is possible to suppress the reflection of light and make the light efficiently incident on the PD41, PD42, and PD43.

[0075] In addition, in the above, an example in which the reflection suppression layer 7 is used in combination with the transparent layer 5 including a plurality of structural body groups 50 has been described. However, if the light can be efficiently incident to some extent only by the reflection suppression layer 7, the plurality of structural body groups 50 may not be provided. In this case, various known spectroscopic elements can be used instead of the structural body group 50.

[0076] In the above-described imaging element 12B, a specific PD may not be covered by the diffraction grating 70. Examples of the specific PD are, for example, a PD located directly below the structural body group 50 and perpendicularly incident with light from the structural body group 50. For such a specific PD, a reflection suppression film can be used to cover it instead of the diffraction grating 70. Regarding this, reference is made to Figure 18 for description.

[0077] Figure 18It is a diagram showing an example of the schematic structure of a specific PD portion of an imaging element. The illustrated imaging element 12B-2 is different from the imaging element 12B ( Figure 17 ) in that it has a reflection suppression layer 7A instead of the reflection suppression layer 7.

[0078] The reflection suppression layer 7A includes, in addition to a plurality of diffraction gratings 70A, a reflection suppression film 71. The plurality of diffraction gratings 70A cover PD41 and PD43, but do not cover PD42 and expose it. Since the structure of the diffraction grating 70A is the same as that of the diffraction grating 70, it will not be described repeatedly. The reflection suppression film 71 is provided to cover the exposed PD42 without a gap. The reflection suppression film 71 has a refractive index different from that of the PD group 40. PD42 is, for example, a photoelectric conversion element corresponding to green (G). As an example of the material of the reflection suppression film 71, for example, resins such as plastics, glass, etc.

[0079] As Figure 18 shown, by using the reflection suppression layer 7A having two types of reflection suppression components, namely, a plurality of diffraction gratings 70 and a reflection suppression film 71, it is possible to adjust the reflection suppression amount for each of PD41, PD42, and PD43, for example.

[0080] Above, one embodiment of the present disclosure has been described, but the imaging element and imaging device of the embodiment can be variously modified without departing from the gist of the embodiment.

[0081] In the above embodiment, an example in which a plurality of structural body groups 50 are provided in the transparent layer 5 has been described. However, the plurality of structural body groups 50 may also be provided on the transparent layer 5 (for example, on the surface on the positive Z-axis side).

[0082] In the above embodiment, SiN and TiO2 are cited as the materials of the structural body 51, etc., but it is not limited thereto. For example, for light with a wavelength of 380 nm to 1000 nm (visible light to near-infrared light), SiN, SiC, TiO2, GaN, etc. can be used as the materials of the structural body 51, etc. Since they have a high refractive index and little absorption loss, they are suitable. When used for light with a wavelength of 800 to 1000 nm (near-infrared light), Si, SiC, SiN, TiO2, GaAs, GaN, etc. can be used as the materials of the structural body 51, etc. Since they have low loss, they are suitable. For light in the long-wavelength near-infrared region (such as 1.3 μm and 1.55 μm as communication wavelengths), in addition to the above materials, InP, etc. can also be used as the materials of the structural body 51, etc.

[0083] In the case where the structure 51 etc. are formed by pasting, coating, etc., examples of the material include polyimides such as fluorinated polyimide, BCB (benzocyclobutene), photocurable resin, UV epoxy resin, acrylic resins such as PMMA, and polymers such as the entire resist.

[0084] In the above-described embodiment, an example in which SiO2 and an air layer are assumed as the material of the transparent layer 5 is shown, but it is not limited thereto. It also includes general glass materials, etc., as long as it has a refractive index smaller than that of the material of the structure 51 etc. and has low loss with respect to the wavelength of the incident light. The transparent layer 5 may also be a transparent layer having a laminated structure composed of multiple materials. In addition, as long as the transparent layer 60 has sufficiently low loss for the wavelength corresponding to the PD to which it should reach, it can be the same material as the color filter, and for example, it can also be an organic material such as resin.

[0085] In the above-described embodiment, the colors corresponding to PD41, PD42, and PD43 are described by taking the RGB primary colors as an example, but it can also correspond to light of wavelengths other than the primary colors (for example, infrared light, ultraviolet light).

[0086] In the above-described embodiment, an example in which one PD group 40 includes 3 PDs, namely PD41, PD42, and PD43, is described, but one PD group may also include 2 or 4 or more PDs. These PDs can be arranged in a one-dimensional direction (for example, in the X-axis direction or the Y-axis direction), or can be arranged in a two-dimensional direction (for example, in the X-axis direction and the Y-axis direction).

[0087] As described above, the present invention has been described based on specific embodiments, but the present invention is not limited to the above-described embodiments, and various modifications can of course be made without departing from its gist.

[0088] The imaging element described above is determined, for example, in the following manner. As referred to Figures 1 to 11As described above, the imaging element 12 includes a plurality of PD groups 40, a transparent layer 5, and a plurality of structure groups 50. The plurality of PD groups 40 each include PD41, PD42, and PD43, and the plurality of PD groups 40 are respectively arranged in a two-dimensional direction (XY plane direction). The transparent layer 5 faces the plurality of PD groups 40, and the transparent layer 5 extends with the two-dimensional direction as the plane direction. The plurality of structure groups 50 are arranged on or within the transparent layer 5 corresponding to the plurality of PD groups 40 in the plane direction of the transparent layer 5. Each of the plurality of structure groups 50 in the plurality of structure groups 50 includes structures 51, 52, and 53 arranged in the same pattern, and each of the plurality of structure groups 50 in the plurality of structure groups 50 is arranged to split incident light toward PD41, PD42, and PD43 in the corresponding PD group 40, respectively. When viewed from above, the relative position between the corresponding PD group 40 and the structure group 50 varies according to the position in two dimensions (on the XY plane).

[0089] In the above-described imaging element 12, the relative position between the corresponding PD group 40 and the structure group 50 varies according to the position in two dimensions. If it is assumed that the relative position is the same at any position in two dimensions, then as previously referred to Figure 9 As described above, the light split by the structure group 50 reaches a position deviated from the centers of PD41, PD42, and PD43. As a result, the light cannot be efficiently incident on PD41, PD42, and PD43, and for example, problems such as deterioration of light reception sensitivity occur. In response to this, in the imaging element 12, by staggering the relative position between the corresponding PD group 40 and the structure group 50, the splitting direction based on the structure group 50 can be made closer to the centers of PD41, PD42, and PD43. Therefore, the light reception sensitivity can be improved.

[0090] When taking the relative position at the central portion in two dimensions in the imaging element 12 as a reference, the offset of the relative position can increase as it approaches the peripheral portion in two dimensions. Thereby, a relative position corresponding to the offset of the incident angle that increases as it approaches the peripheral portion can be set.

[0091] As referred to Figure 5 and Figure 6As described with reference to etc., the columnar structures 51, 52, and 53 are columnar structures having a refractive index higher than that of the portions between them. When viewed from above, at least some of the columnar structures 51, 52, and 53 have different widths from each other. When viewed from the side, the columnar structures 51, 52, and 53 may have the same height. At least some of the columnar structures 51, 52, and 53 may have different refractive indices from each other. For example, by disposing such columnar structures 51, 52, and 53, the structure group 50 (transparent layer 5) can have a spectroscopic function, and incident light can be spectroscopically separated toward the PD41, PD42, and PD43, respectively. In addition, for example, it can be manufactured more easily than in the case of providing a plurality of columnar structures having different heights.

[0092] As described with reference to Figures 12 to 14 etc., the imaging element 12A includes a plurality of lenses 61 provided corresponding to the plurality of structure groups 50A, respectively. When viewed from above, the relative positions between the corresponding structure groups 50A and the lenses 61 may be different depending on the two-dimensional position. Alternatively, as described with reference to Figure 12 , Figure 15 and Figure 16 etc., the imaging element 12A may include lenses 61, 62, and 63 provided for the plurality of structure groups 50A, respectively, and having shapes corresponding to the two-dimensional positions. Thereby, the incident angles of light incident on the transparent layer 5A in the outer peripheral portion and the intermediate portion can be made close to the incident angle in the central portion. For example, compared with the case of using only the plurality of structure groups 50, it is easier to spectroscopically separate light toward the centers of the PD41, PD42, and PD43 in the PD group 40, respectively.

[0093] As described with reference to Figure 17 etc., the imaging element 12B may include a plurality of diffraction gratings 70. The plurality of diffraction gratings 70 are periodically provided so as to cover at least a part of the plurality of PD groups 40, and the plurality of diffraction gratings 70 have effective refractive indices having different magnitudes from the refractive indices of the plurality of PD groups 40. Thereby, reflection of light can be suppressed, and light can be efficiently incident on the PD41, PD42, and PD43.

[0094] As described with reference to Figure 18As described above, the plurality of diffraction gratings 70 may expose the PD42 among the PD41, PD42, and PD43 included in each of the plurality of PD groups 40 without covering it. The imaging element 12 may include an anti-reflection film 71. The anti-reflection film 71 is provided to cover the exposed PD42 without a gap, and the anti-reflection film 71 has a refractive index with a magnitude different from that of the plurality of PD groups 40. For example, by using the anti-reflection layer 7A including such two anti-reflection components as the plurality of diffraction gratings 70 and the anti-reflection film 71, the anti-reflection amount can be adjusted for each of the PD41, PD42, and PD43.

[0095] Refer to Figure 1 The imaging device 10 described above is also an aspect of the present disclosure. That is, the imaging device 10 includes an imaging element 12 and a signal processing unit 13 that generates an image signal based on an electrical signal obtained from the imaging element 12. Thereby, the imaging device 10 capable of improving the light reception efficiency is obtained.

[0096] Description of reference numerals

[0097] 3 Wiring layer

[0098] 4 PD layer

[0099] 5 Transparent layer

[0100] 7 Anti-reflection layer

[0101] 10 Imaging device

[0102] 12 Imaging element

[0103] 13 Signal processing unit

[0104] 40 PD group

[0105] 41 PD

[0106] 42 PD

[0107] 43 PD

[0108] 50 Structure group

[0109] 51 Structure

[0110] 52 Structure

[0111] 53 Structure

[0112] 61 Lens

[0113] 62 Lens

[0114] 63 Lens

[0115] 70 Diffraction grating

[0116] 71 Reflective Inhibiting Film

Claims

1. An imaging element, characterized in that, Comprising: A plurality of photoelectric conversion element groups, each of which includes a plurality of photoelectric conversion elements, and the plurality of photoelectric conversion element groups are arranged in a two-dimensional direction; A transparent layer, which faces the plurality of photoelectric conversion element groups and extends in the two-dimensional direction as a plane direction; And A plurality of structure groups, which are arranged in the plane direction of the transparent layer corresponding to the plurality of photoelectric conversion element groups on or within the transparent layer, Each of the plurality of structure groups includes a plurality of structures arranged in the same pattern, and each of the plurality of structure groups is configured to split incident light for the photoelectric conversion elements of the corresponding photoelectric conversion element group, In a plan view, the relative position between the corresponding photoelectric conversion element group and the structure group is different according to the position in two dimensions.

2. The imaging element according to claim 1, wherein Based on the relative position at the central portion in two dimensions, the offset of the relative position becomes larger as it approaches the peripheral portion in two dimensions.

3. The imaging element according to claim 1 or 2, wherein The plurality of structures are columnar structures having a refractive index higher than that of the portions between the plurality of structures, In a plan view, at least some of the plurality of structures have different widths from each other, In a side view, the plurality of structures have the same height.

4. The imaging element according to claim 1 or 2, wherein The plurality of structures are columnar structures having a refractive index higher than that of the portions between the plurality of structures, At least some of the plurality of structures have different refractive indices from each other, In a side view, the plurality of structures have the same height.

5. The imaging element according to claim 1 or 2, wherein The imaging element has a plurality of lenses, and the plurality of lenses are provided corresponding to the plurality of structure groups respectively, In a plan view, the relative position between the corresponding structure group and the lens is different according to the position in two dimensions.

6. The imaging element according to claim 1 or 2, wherein The imaging element has a plurality of lenses, and the plurality of lenses are provided corresponding to the plurality of structure groups respectively, and the plurality of lenses have shapes corresponding to the positions in two dimensions.

7. The imaging element according to claim 1 or 2, wherein The imaging element has a plurality of diffraction gratings, which are periodically arranged to cover at least a part of the plurality of photoelectric conversion element groups, and the plurality of diffraction gratings have effective refractive indices of different magnitudes from the refractive indices of the plurality of photoelectric conversion element groups.

8. The imaging element according to claim 7, wherein The plurality of diffraction gratings do not cover a specific photoelectric conversion element among the plurality of photoelectric conversion elements included in each of the plurality of photoelectric conversion element groups, but expose the specific photoelectric conversion element, The imaging element includes a film that is provided to cover the exposed photoelectric conversion elements without a gap, and the film has a refractive index different in magnitude from that of the plurality of photoelectric conversion element groups.

9. An imaging device, characterized in that, Comprising: The imaging element according to any one of claims 1, 2, and 8; and A signal processing unit that generates an image signal based on an electrical signal obtained from the imaging element.

Images