Solid-state imaging device and electronic equipment

Abstract

A solid-state imaging device capable of obtaining an image with high image quality is provided. The solid-state imaging device includes a pixel unit configured such that a plurality of unit pixels are arranged in a two-dimensional array. The plurality of unit pixels are configured to include a plurality of photoelectric conversion units and a plurality of microlenses. The plurality of photoelectric conversion units are formed on a substrate and generate signal charges corresponding to the amount of incident light. The plurality of microlenses are configured such that one microlens is formed for one group of photoelectric conversion units among the plurality of groups of photoelectric conversion units. Each group of photoelectric conversion units is composed of at least two adjacent photoelectric conversion units. The photoelectric conversion units are insulated from each other by an impurity layer, and the plurality of microlenses guide incident light to each of the plurality of groups of photoelectric conversion units. In addition, the solid-state imaging device includes a plurality of light absorption layers formed between the microlenses and the substrate and absorbing a part of the incident light guided to the groups of photoelectric conversion units by the microlenses.

Description

Technical Field

[0001] The present technology relates to a solid-state imaging device and an electronic device. Background Art

[0002] In related art, as a structure in which two adjacent photoelectric conversion units share one microlens, a solid-state imaging device that can calculate the distance to a subject based on signal charges generated by two photoelectric conversion units has been proposed (for example, see Patent Document 1). In the solid-state imaging device disclosed in Patent Document 1, a scatterer is provided at a position where the microlens converges light, so that the converged light is scattered by the scatterer and distributed toward two adjacent photoelectric conversion units. In addition, a difference in light reception sensitivity between photoelectric conversion units due to misalignment during manufacturing is suppressed.

[0003] Citation List

[0004] Patent Documents

[0005] Patent Document 1: JP 2013-211413 A Summary of the Invention

[0006] Technical Problem

[0007] However, in the solid-state imaging device disclosed in Patent Document 1, since light is distributed by the scatterer, scattered light may invade surrounding photoelectric conversion units, which may cause optical color mixing. Therefore, the quality of an image obtained by the solid-state imaging device may deteriorate.

[0008] An object of the present disclosure is to provide a solid-state imaging device and an electronic device capable of obtaining an image with higher quality.

[0009] Technical Solution to Solve the Problem

[0010] The solid-state imaging device of the present disclosure includes: (a) a pixel unit configured such that a plurality of unit pixels are arranged in a two-dimensional array, the plurality of unit pixels being configured to include a plurality of photoelectric conversion units and a plurality of microlenses, the plurality of photoelectric conversion units being formed on a substrate and generating signal charges corresponding to the amount of incident light, the plurality of microlenses being configured such that one microlens is formed for one group of photoelectric conversion units among a plurality of groups of photoelectric conversion units, each group of photoelectric conversion units being composed of at least two or more adjacent photoelectric conversion units, the photoelectric conversion units being insulated from each other by an impurity layer, and the plurality of microlenses guiding incident light to each of the plurality of groups of photoelectric conversion units; and (b) a plurality of light absorption layers formed between the microlenses and the substrate and absorbing a part of the incident light guided to the groups of photoelectric conversion units by the microlenses.

[0011] In addition, the electronic device of the present disclosure includes: (a) a solid-state imaging device including a pixel unit and a plurality of light absorption layers, the pixel unit being configured such that a plurality of unit pixels are arranged in a two-dimensional array, the plurality of unit pixels being configured to include a plurality of photoelectric conversion units and a plurality of microlenses, the plurality of photoelectric conversion units being formed on a substrate and generating signal charges corresponding to the amount of incident light, the plurality of microlenses being configured such that one microlens is formed for one group of photoelectric conversion units among the plurality of groups of photoelectric conversion units, each group of photoelectric conversion units being composed of at least two or more adjacent photoelectric conversion units, the photoelectric conversion units being insulated from each other by an impurity layer, the plurality of microlenses guiding incident light to each of the plurality of groups of photoelectric conversion units, the plurality of light absorption layers being formed between the microlenses and the substrate and absorbing a part of the incident light guided to the groups of photoelectric conversion units by the microlenses; (b) an optical lens that forms image light from a subject on the imaging surface of the solid-state imaging device; and (c) a signal processing circuit that performs signal processing on a signal output from the solid-state imaging device. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 is a diagram showing the overall configuration of a solid-state imaging device according to a first embodiment of the present disclosure.

[0013] Figure 2 is a diagram showing a cross-sectional configuration of a pixel region along line A-A in Figure 1 .

[0014] Figure 3A is an enlarged diagram showing the cross-sectional configuration of the pixel region.

[0015] Figure 3B is a diagram showing a planar configuration of a color filter and a light absorption layer along line B-B in Figure 3A .

[0016] Figure 3C is a diagram showing a planar configuration of a group of photoelectric conversion units and photoelectric conversion units along line C-C in Figure 3A .

[0017] Figure 4A is an enlarged diagram showing the cross-sectional configuration of the pixel region.

[0018] Figure 4B is a diagram showing a planar configuration of a color filter and a light absorption layer along line D-D in Figure 4A .

[0019] Figure 4C is a diagram showing a planar configuration of a group of photoelectric conversion units and photoelectric conversion units along line E-E in Figure 4A .

[0020] Figure 5AIt is an enlarged view showing the cross-sectional structure of a pixel region.

[0021] Figure 5B It is a view showing Figure 5A the planar structure of a color filter and a light absorption layer along line F-F in

[0022] Figure 6 It is an enlarged view showing the cross-sectional structure of a pixel region.

[0023] Figure 7 It is an enlarged view showing the cross-sectional structure of a pixel region of a solid-state imaging device in the related art.

[0024] Figure 8A It is an enlarged view showing the cross-sectional structure of a pixel region.

[0025] Figure 8B It is a view showing along Figure 8A the planar structure of a color filter and a light absorption layer along line G-G in

[0026] Figure 9A It is an enlarged view showing the cross-sectional structure of a pixel region.

[0027] Figure 9B It is a view showing along Figure 9A the planar structure of a color filter and a light absorption layer along line H-H in

[0028] Figure 10 It is a view showing the planar structure of a color filter and a light absorption layer.

[0029] Figure 11 It is an enlarged view showing the cross-sectional structure of a pixel region.

[0030] Figure 12A It is a view showing the manufacturing process flow of a color filter and a light absorption layer.

[0031] Figure 12B It is a view showing the manufacturing process flow of a color filter and a light absorption layer.

[0032] Figure 12C It is a view showing the manufacturing process flow of a color filter and a light absorption layer.

[0033] Figure 13 It is a view showing the planar structure of a color filter and a light absorption layer of a solid-state imaging device according to a modified example.

[0034] Figure 14 It is a view showing the planar structure of a color filter and a light absorption layer of a solid-state imaging device according to a modified example.

[0035] Figure 15It is a diagram showing a planar structure of a color filter and a light absorption layer of a solid-state imaging device according to a modified example.

[0036] Figure 16 It is a schematic configuration diagram showing an electronic device according to a second embodiment of the present disclosure. Detailed Description

[0037] Hereinafter, reference will be made to Figures 1 to 16 Examples of the solid-state imaging device 1 and the electronic device according to the embodiments of the present disclosure will be described. The embodiments of the present disclosure will be described in the following order. Note that the present disclosure is not limited to the following examples. In addition, the effects described in this specification are merely illustrative and not restrictive, and other effects may be obtained.

[0038] 1. First Embodiment: Solid-State Imaging Device

[0039] 1-1 Overall Structure of Solid-State Imaging Device

[0040] 1-2 Structure of Main Components

[0041] 1-3 Manufacturing Method of Light Absorption Layer

[0042] 1-4 Modified Example

[0043] 2. Second Embodiment: Electronic Device

[0044] <1. First Embodiment>

[0045] [1-1 Overall Structure of Solid-State Imaging Device]

[0046] The solid-state imaging device 1 according to the first embodiment of the present disclosure will be described. Figure 1 It is a schematic configuration diagram showing the overall structure of the solid-state imaging device 1 according to the first embodiment of the present disclosure.

[0047] Figure 1 The solid-state imaging device 1 in Figure 16 is a back-illuminated complementary metal oxide semiconductor (CMOS) image sensor. As

[0048] shown in Figure 1 , the solid-state imaging device 1 (101) allows image light (incident light 106) from a subject to enter through an optical lens 102, converts the amount of incident light 106 imaged on the imaging surface into an electrical signal in units of pixels, and outputs the electrical signal as a pixel signal.

[0049] The pixel region 3 includes a plurality of pixels 9 regularly arranged on the substrate 2 in a two-dimensional array. The pixel 9 includes Figure 2 the photoelectric conversion unit 21 shown and a plurality of pixel transistors (not shown). As the plurality of pixel transistors, for example, four transistors, namely, a transfer transistor, a reset transistor, a selection transistor, and an amplification transistor, can be adopted. Additionally, for example, three transistors excluding the selection transistor can be adopted.

[0050] The vertical drive circuit 4 is constituted by, for example, a shift register, selects a desired pixel drive line 10, supplies a pulse for driving the pixel 9 to the selected pixel drive line 10, and drives the pixels 9 row by row. That is, the vertical drive circuit 4 performs selective scanning on the pixels 9 in the pixel region 3 row by row in the vertical direction, and supplies a pixel signal based on signal charges generated according to the amount of light received by the photoelectric conversion unit 21 in each pixel 9 to the column signal processing circuit 5 via the vertical signal line 11.

[0051] For example, the column signal processing circuit 5 is provided for each column of the pixels 9, and performs signal processing such as noise removal on the signals output from the pixels 9 corresponding to one row for each pixel column. For example, the column signal processing circuit 5 performs signal processing such as correlated double sampling (CDS) and analog - digital (AD) conversion to remove fixed - pattern noise inherent to the pixels.

[0052] The horizontal drive circuit 6 is constituted by, for example, a shift register, sequentially outputs horizontal scan pulses to the column signal processing circuit 5 to sequentially select each column signal processing circuit 5, and outputs the signal - processed pixel signals from each column signal processing circuit 5 to the horizontal signal line 12.

[0053] The output circuit 7 performs signal processing on the pixel signals sequentially supplied from each column signal processing circuit 5 via the horizontal signal line 12, and outputs the pixel signals. Examples of signal processing that can be used include buffering, black - level adjustment, array - deviation correction, and various digital signal processes, etc.

[0054] The control circuit 8 generates a clock signal or a control signal serving as an operation reference for the vertical drive circuit 4, the column signal processing circuit 5, the horizontal drive circuit 6, etc. based on a vertical synchronization signal, a horizontal synchronization signal, and a main clock signal. Additionally, the control circuit 8 outputs the generated clock signal or control signal to the vertical drive circuit 4, the column signal processing circuit 5, the horizontal drive circuit 6, etc.

[0055] [1 - 2 Structure of Main Components]

[0056] Next, the Figure 1The detailed structure of the solid-state imaging device 1 in Figure 2 is a diagram showing a cross-sectional structure of a pixel region 3 of the solid-state imaging device 1 according to the first embodiment. In Figure 2 a back-illuminated CMOS image sensor (CMOS type solid-state imaging device) is used as the solid-state imaging device 1.

[0057] As Figure 2 shown, the solid-state imaging device 1 according to the first embodiment includes a light-receiving layer 15 in which a substrate 2, an insulating film 13, and a light-shielding film 14 are laminated in this order. In addition, a light-collecting layer 18 is formed on the surface of the light-receiving layer 15 on the insulating film 13 side (hereinafter, also referred to as "rear surface S1"), and in this light-collecting layer 18, a color filter 16 and a microlens 17 (on-chip lens, wafer lens) are laminated in this order. Further, a wiring layer 19 and a support substrate 20 are laminated in this order on the surface of the light-receiving layer 15 on the substrate 2 side (hereinafter, also referred to as "surface S2"). At the same time, the rear surface S1 of the light-receiving layer 15 and the rear surface of the insulating film 13 are the same surface, so in the following description, the rear surface of the insulating film 13 is referred to as "rear surface S1". In addition, the surface S2 of the light-receiving layer 15 and the surface of the substrate 2 are the same surface, so in the following description, the surface of the substrate 2 is referred to as "surface S2".

[0058] The substrate 2 is made of a semiconductor substrate containing, for example, silicon (Si), and as Figure 1 shown, a pixel region 3 is formed. As Figure 2 shown, in the pixel region 3, a plurality of photoelectric conversion units 21 formed on the substrate 2, that is, a plurality of pixels 9 each configured to include a plurality of photoelectric conversion units 21 embedded in the substrate 2 are arranged in a two-dimensional array. In the photoelectric conversion unit 21, signal charges corresponding to the amount of incident light 22 are generated and the generated signal charges are accumulated.

[0059] Regarding the photoelectric conversion unit 21, as Figure 3A , Figure 3B and Figure 3C as well as Figure 4A , Figure 4B and Figure 4C shown, at least two or more adjacent photoelectric conversion units 21 constitute a photoelectric conversion unit group 23. In Figure 3A , Figure 3B and Figure 3C , a photoelectric conversion unit group 23 composed of four photoelectric conversion units 21 is shown. In addition, in Figure 4A , Figure 4B and Figure 4C , a photoelectric conversion unit group 23 composed of two photoelectric conversion units 21 is shown. For Figure 3AThe color filter 16 and the microlens 17 shown perform pupil correction, which will be described later. An impurity layer 24 formed by implanting impurities into the substrate 2 is formed between the photoelectric conversion units 21 that make up the photoelectric conversion unit group 23. As the impurity, for example, a material that electrically separates between the photoelectric conversion units 21 and allows the incident light 22 to pass through the impurity layer 24 can be used. For example, elements such as phosphorus, arsenic, and boron can be employed.

[0060] In addition, between the photoelectric conversion unit groups 23, a groove portion 25 formed along the depth direction from the surface on the insulating film 13 side of the substrate 2 (hereinafter, also referred to as “rear surface S3”) and an inter-pixel light-shielding portion 26 configured to include the insulating film 13 filled in the groove portion 25 are formed, so that the photoelectric conversion unit groups 23 are physically separated from each other.

[0061] The insulating film 13 continuously covers the entire rear surface S3 side (the entire light-receiving surface side) of the substrate 2. In addition, the light-shielding film 14 is formed in a lattice shape such that the light-receiving surfaces of the respective ones of the plurality of photoelectric conversion unit groups 23 are opened in a part on the rear surface S1 side (a part of the light-receiving surface side) of the insulating film 13.

[0062] The color filter 16 is formed corresponding to each photoelectric conversion unit group 23 on the rear surface S1 side (light-receiving surface side) of the insulating film 13. Accordingly, the color filter 16 forms a color filter array 27 regularly arranged in a two-dimensional array. Each color filter 16 is configured to allow a specific wavelength of the incident light 22, such as red, green, or blue, which is expected to be received by the photoelectric conversion unit group 23, to pass through. In addition, the color filter 16 allows the incident light 22 having a specific wavelength to pass through, and causes the passed incident light 22 to be incident on the photoelectric conversion unit 21 of the substrate 2.

[0063] In addition, as Figure 3A and Figure 5A shown, so-called pupil correction is performed on each color filter 16. In the pupil correction, from the central portion of the pixel region 3 (the pixel unit 30, which will be described later) toward the outer peripheral portion of the pixel region 3, when viewed in a plan view, the central portion of the color filter 16 is offset toward the central portion side of the pixel region 3 (pixel unit 30) compared to the center of the photoelectric conversion unit group 23 corresponding to the color filter 16. Compared with the color filter 16 etc. shown in Figure 3A shown, Figure 5A the color filter 16 etc. formed on the outer peripheral portion side of the pixel region 3 are shown. By performing pupil correction on the color filter 16, in the outer peripheral portion of the pixel region 3 (pixel unit 30), the inclined incident light 22 incident on the photoelectric conversion unit 21 can pass through the color filter 16 via the microlens 17.

[0064] The microlens 17 is formed corresponding to each photoelectric conversion unit group 23 on the rear surface S4 side (light receiving surface side) of the color filter 16. That is, one microlens 17 is formed for one photoelectric conversion unit group 23 among the plurality of photoelectric conversion unit groups 23. Therefore, the microlenses 17 form a microlens array 28 regularly arranged in a two-dimensional array. Each microlens 17 is configured to collect the incident light 22 and guide the collected incident light 22 to each of the plurality of photoelectric conversion units 21 via the color filter 16.

[0065] In addition, as Figure 3A and Figure 5A shown, so-called pupil correction is performed on each microlens 17. In the pupil correction, from the central portion of the pixel region 3 (pixel unit 30) toward the outer peripheral portion of the pixel region 3, when observed in a plan view, the central portion of the microlens 17 is offset toward the central portion side of the pixel region 3 (pixel unit 30) compared with the center of the photoelectric conversion unit group 23 corresponding to the microlens 17. By performing pupil correction on the microlens 17, in the outer peripheral portion of the pixel region 3 (pixel unit 30), the oblique incident light 22 incident on the microlens 17 can be incident on the photoelectric conversion unit 21.

[0066] The structure including one photoelectric conversion unit group 23 and one microlens 17 is regarded as a unit pixel 29, and the unit pixels 29 are arranged in a two-dimensional array to form the pixel unit 30.

[0067] In this way, when adopting a structure in which one microlens 17 is shared by at least two or more adjacent photoelectric conversion units 21 (photoelectric conversion unit groups 23), there is a difference between the signal charges generated by each photoelectric conversion unit 21 included in the same photoelectric conversion unit group 23. Therefore, in the solid-state imaging device 1 according to the first embodiment, the distance to the subject can be calculated based on this difference.

[0068] As Figure 3A 、 Figure 3B 、 Figure 5A 、 Figure 5B and Figure 6 shown, a light absorption layer 31 corresponding to each photoelectric conversion unit group 23 is formed between the microlens 17 and the substrate 2. In Figure 3A 、 Figure 3B 、 Figure 5A and Figure 5B shown, the light absorption layer 31 formed on the surface of the color filter 16 on the microlens 17 side is shown. In addition, in Figure 6In the figure, a light absorption layer 31 is shown as being formed in a surface on the substrate 2 side of the color filter 16. Each light absorption layer 31 is formed of a material capable of absorbing incident light 22. Further, the area of the planar shape of the light absorption layer 31 is smaller than the area of the planar shape of the color filter 16, that is, smaller than the area of the planar shape of the photoelectric conversion unit group 23. By making the area of the planar shape of the light absorption layer 31 smaller than the area of the planar shape of the photoelectric conversion unit group 23, as Figure 3A shown, the light absorption layer 31 can absorb a part of the incident light 22 guided to the photoelectric conversion unit group 23 through the microlens 17. In Figure 3A the figure, the optical path 32 of the incident light 22 on the outer peripheral side of the microlens 17 among the incident lights 22 guided to the photoelectric conversion unit group 23 through the microlens 17 is indicated by a dashed line. Further, in Figure 3A the figure, the region 33 where the incident light 22 is absorbed and attenuated by the light absorption layer 31 is indicated by halftone dots.

[0069] Here, the incident light 22 is incident obliquely on the outer peripheral portion of the pixel unit 30. Therefore, in the case where the light absorption layer 31 is not formed, as Figure 7 shown, the incident light 22 incident on the photoelectric conversion unit 21 (hereinafter, also referred to as "central-side photoelectric conversion unit 21a") located on the central portion side of the pixel unit 30 in the photoelectric conversion unit group 23 passes through the impurity layer 24 and is incident on the photoelectric conversion unit 21 (hereinafter, also referred to as "outer-peripheral-side photoelectric conversion unit 21b") located on the outer peripheral side of the pixel unit 30. Therefore, the difference between the signal charges generated by the central-side photoelectric conversion unit 21a and the outer-peripheral-side photoelectric conversion unit 21b increases. Therefore, the difference (same-color sensitivity difference) between the signal charges generated by the photoelectric conversion units 21 included in the same photoelectric conversion unit group 23 (that is, two or more photoelectric conversion units 21, the incident light 22 is guided to the two or more photoelectric conversion units 21 by the same microlens 17 and light of the same wavelength (color) is incident on the two or more photoelectric conversion units 21) may increase. As a result, the quality of the image obtained by the remosaic process may deteriorate.

[0070] As a method for reducing the difference between the signal charges, for example, it is also possible to consider separating the photoelectric conversion units 21 included in the same photoelectric conversion unit group 23 by the inter-pixel light-shielding portion 26. However, in the case where the photoelectric conversion units 21 are separated by the inter-pixel light-shielding portion 26, the incident light 22 scatters in the inter-pixel light-shielding portion 26, so that scattered light may intrude into the photoelectric conversion units 21 included in other photoelectric conversion unit groups 23, and optical color mixing occurs. Therefore, the quality of the image obtained by the solid-state imaging device 1 may deteriorate.

[0071] On the other hand, in the solid-state imaging device 1 according to the first embodiment, since the light absorption layer 31 is provided, a configuration in which a part of the incident light 22 transmitted through the microlens 17 is absorbed can be adopted, thereby reducing the difference between the signal charges generated by the respective photoelectric conversion units 21 included in the same photoelectric conversion unit group 23. For example, as Figure 3A and Figure 3B show, by forming the light absorption layer 31 near the central portion of the color filter 16, the amount of the incident light 22 directly incident on the peripheral-side photoelectric conversion unit 21b can be reduced, and thus the difference between the signal charges generated by the central-side photoelectric conversion unit 21a and the peripheral-side photoelectric conversion unit 21b can be reduced. Therefore, deterioration in the quality of the image obtained by the rearrangement mosaic process can be suppressed. In addition, for example, since light scattering of the incident light 22 does not occur unlike the case of using the inter-pixel light shielding portion 26, optical color mixing can be prevented.

[0072] In addition, for example, as Figure 8A shows, by forming the light absorption layer 31 closer to the central portion of the pixel unit 30 than the central portion of the color filter 16, the amount of the incident light 22 incident on the peripheral-side photoelectric conversion unit 21b via the central-side photoelectric conversion unit 21a and the impurity layer 24 can be reduced, and thus the difference between the signal charges generated by the central-side photoelectric conversion unit 21a and the peripheral-side photoelectric conversion unit 21b can be reduced.

[0073] In addition, as Figure 3A , Figure 3B , Figure 5A and Figure 5B show, as the distance between the unit pixel 29 in which the light absorption layer 31 is formed and the central portion of the pixel unit 30 becomes farther, when observed in a plan view, the position of the light absorption layer 31 with respect to the color filter 16 becomes closer to the central portion side of the pixel unit 30. Figure 3A and Figure 3B show a case where the distance between the light absorption layer 31 and the central portion of the pixel unit 30 is relatively close. In addition, Figure 5A and Figure 5B show a case where the distance between the light absorption layer 31 and the central portion of the pixel unit 30 is relatively far. Therefore, in the outer peripheral portion of the pixel unit 30, the incident light 22 that is obliquely incident on the photoelectric conversion unit 21 and transmitted through the central-side photoelectric conversion unit 21a and the impurity layer 24 and incident on the peripheral-side photoelectric conversion unit 21b can be more appropriately absorbed, and the difference between the signal charges generated by the central-side photoelectric conversion unit 21a and the peripheral-side photoelectric conversion unit 21b can be reduced.

[0074] In addition, as Figure 3A , Figure 3B ,Figure 5A and Figure 5B As shown, the planar shape of the light absorption layer 31 is a predetermined shape as follows: as the distance between the unit pixel 29 in which the light absorption layer 31 is formed and the central portion of the pixel unit 30 becomes farther, the light absorption layer 31 becomes longer in the direction parallel to the line passing through the central portions of the unit pixel 29 and the pixel unit 30. Figure 5A and Figure 5B shows a light absorption layer 31 that is longer than the light absorption layer 31 shown in Figure 3A and Figure 3B Therefore, in the outer peripheral portion of the pixel unit 30, among the incident light 22 that is obliquely incident on the photoelectric conversion unit 21, the incident light 22 that passes through the central-side photoelectric conversion unit 21a and the impurity layer 24 and is incident on the outer peripheral-side photoelectric conversion unit 21b can be more appropriately absorbed, and the difference between the signal charges generated by the central-side photoelectric conversion unit 21a and the outer peripheral-side photoelectric conversion unit 21b can be reduced.

[0075] The predetermined shape can be, for example, a rectangular shape as shown in Figure 3B , Figure 5B and Figure 8B , or an elliptical shape as shown in Figure 9A and Figure 9B . In the case of using a rectangular shape, the formation of the light absorption layer 31 can be made easier. In addition, light is concentrated by the microlens 17, and the light absorption layer 31 is provided in the central portion of the color filter 16 having the strongest light intensity, whereby the reduction in sensitivity and the sensitivity difference of the same color can be suppressed simultaneously. Here, the cross-sectional shape of the obliquely incident light 22 generated in the outer peripheral portion of the pixel region 3 is an elliptical shape. Therefore, in the case of using an elliptical shape as the predetermined shape, only the central portion of the color filter 16 having the strongest light intensity can be covered, and the reduction in sensitivity can be minimized.

[0076] In addition, the thickness of the light absorption layer 31 can be smaller than the thickness of the color filter 16. By reducing the thickness of the light absorption layer 31, the distance between the microlens 17 and the photoelectric conversion unit 21 can be further reduced, and the solid-state imaging device 1 according to the first embodiment can be further miniaturized.

[0077] In addition, as the material of the light absorption layer 31, for example, the same material as any one of the materials of the color filter 16 can be used. By using the same material, the light absorption layer 31 can be formed using, for example, the equipment for forming the color filter 16, and the light absorption layer 31 can be easily formed.

[0078] In this case, for example, as shown in Figure 3BAs shown, the color filter 16 and the light absorption layer 31 formed in the color filter 16 can be formed of different materials. That is, a configuration can be adopted in which the wavelength region of the light transmitted through the color filter 16 and the wavelength region of the light transmitted through the light absorption layer 31 formed in the color filter 16 are different. With this configuration, compared with the case where the wavelength region of the light transmitted through the color filter 16 and the wavelength region of the light transmitted through the light absorption layer 31 are the same, the function of the light absorption layer 31 to absorb the incident light 22 can be improved.

[0079] In addition, for example, as Figure 10 shown, the color filter 16 and the light absorption layer 31 formed in the color filter 16 can be formed of the same material. That is, a configuration can be adopted in which the wavelength region of the light transmitted through the color filter 16 and the wavelength region of the light transmitted through the light absorption layer 31 formed in the color filter 16 are the same. With this configuration, the light absorption layer 31 can be formed when the color filter 16 is formed, and the light absorption layer 31 can be easily formed.

[0080] The wiring layer 19 is formed on the surface S2 side of the substrate 2 and is configured to include wirings 35 laminated in multiple layers (three layers in Figure 2 ) with an interlayer insulating film 34 therebetween. The pixel transistors constituting the pixel 9 are driven via the multilayer wirings 35 formed in the wiring layer 19.

[0081] The support substrate 20 is formed on the surface of the wiring layer 19 on the side opposite to the surface facing the substrate 2. The support substrate 20 is a substrate for ensuring the strength of the substrate 2 during the manufacturing stage of the solid-state imaging device 1. As the material of the support substrate 20, for example, silicon (Si) can be used.

[0082] In the solid-state imaging device 1 having the above configuration, light is irradiated from the back surface side of the substrate 2 (the back surface S1 side of the light receiving layer 15), the irradiated light passes through the microlens 17 and the color filter 16, and the transmitted light is photoelectrically converted by the photoelectric conversion unit 21 to generate signal charges. In addition, the generated signal charges pass through the pixel transistors formed on the surface S2 side of the substrate 2 and are output as pixel signals through the vertical signal lines 11 shown in Figure 1 .

[0083] In addition, the distance to the subject can be calculated based on the difference between the signal charges generated by the respective photoelectric conversion units 21 included in the same photoelectric conversion unit group 23 among the generated signal charges.

[0084] [1-3 Manufacturing Method of Light Absorption Layer]

[0085] Next, the manufacturing method of the light absorption layer 31 of the solid-state imaging device 1 according to the first embodiment will be described.Figure 11 FIG. 3 shows a pixel region 3 including a light absorption layer 31 fabricated by the present manufacturing method.

[0086] Figure 11 FIG. 4 shows a mixture of the light absorption layer 31 formed on the surface on the micro-lens 17 side of the color filter 16 and the light absorption layer 31 formed on the surface on the substrate 2 side of the color filter 16. Further, the color filter 16 and the light absorption layer 31 formed in the color filter 16 are made of different materials. That is, on the surface on the substrate 2 side of the color filter 16 (labeled "16R" in Figure 11 ), a light absorption layer 31 (labeled "31G" in Figure 11 ) that transmits green wavelengths is formed, and on the surface on the micro-lens 17 side of the color filter 16 (labeled "16G" in Figure 11 ), a light absorption layer 31 (labeled "31B" in Figure 11 ) that transmits blue wavelengths is formed. Further, although not shown in Figure 11 , a color filter 16G that transmits green wavelengths is formed on the surface on the substrate 2 side of the color filter 16 that transmits blue wavelengths. Further, the thickness of the light absorption layer 31 (31G, 31B) is the same as the thickness of the color filter 16 (16R, 16G).

[0087] In the method for manufacturing the light absorption layer 31 of the solid-state imaging device 1 according to the first embodiment, first, (1) a color filter resist that transmits green wavelengths is coated on the entire back surface S1 of the light receiving layer 15. Then, (2) the coated color filter resist is exposed by irradiating it with a UV lamp through a mask that forms holes at positions for forming the color filter 16G that transmits green wavelengths and the light absorption layer 31G. Then, (3) the unexposed color filter resist is removed from the back surface S1 of the light receiving layer 15. Thus, as Figure 12A shown, the color filter 16G that transmits green wavelengths and the light absorption layer 31G are formed.

[0088] Then, the above steps (1) to (3) are performed using a color filter resist that transmits red wavelengths. Thus, as Figure 12B shown, the color filter 16R that transmits red wavelengths is formed. Then, the above steps (1) to (3) are performed using a color filter resist that transmits blue wavelengths. Thus, the color filter 16 that transmits blue wavelengths and the light absorption layer 31B are formed (see Figure 12C)。In this way, when forming the color filter 16, the light absorption layer 31 formed of the same material as the color filter 16 is formed simultaneously. Therefore, the number of steps can be reduced compared to the method in which the step of forming the light absorption layer 31 is another step.

[0089] Note that, as Figure 3A shown, etc., in the case where the thickness of the light absorption layer 31 is made smaller than the thickness of the color filter 16, the following methods can be used: at the position where the light absorption layer 31 is to be formed, reduce the coating amount of the color filter resist, increase the rotation speed of the spin coater used for coating so that the color filter resist is spread thinly, or lower the viscosity of the material.

[0090] As described above, in the solid-state imaging device 1 according to the first embodiment, a plurality of light absorption layers 31 are provided, and these light absorption layers 31 are formed between the microlens 17 and the substrate 2 and absorb a part of the incident light 22 guided to the photoelectric conversion unit group 23 by the microlens 17. Therefore, for example, the amount of incident light 22 incident on the photoelectric conversion units 21 included in the same photoelectric conversion unit group 23 can be controlled by adjusting the pattern shape and position of the light absorption layer 31, and the difference (same-color sensitivity difference) between the signal charges generated by the photoelectric conversion units 21 can be reduced. As a result, deterioration of the quality of the image obtained by the rearrangement mosaic process can be suppressed. In addition, for example, since scattering of the incident light 22 does not occur unlike the case of using a scatterer for scattering light and the inter-pixel light-shielding portion 26, optical color mixing can be prevented. As a result, a solid-state imaging device 1 capable of obtaining an image with higher image quality can be provided.

[0091] Furthermore, in the solid-state imaging device 1 according to the first embodiment, the light absorption layer 31 absorbs a part of the incident light 22 that has passed through the microlens 17, so that the difference between the signal charges generated by the respective photoelectric conversion units 21 included in the same photoelectric conversion unit group 23 is reduced. Therefore, for example, the sensitivity difference between the photoelectric conversion units 21 included in the same photoelectric conversion unit group 23 can be reduced. Therefore, the quality of the image obtained by the rearrangement mosaic process can be further improved.

[0092] [1-4 Modification Examples]

[0093] (1) In the solid-state imaging device 1 according to the first embodiment, the case where the planar shape of the light absorption layer 31 is a rectangular shape or an elliptical shape has been described as an example. However, for example, as Figure 14As shown, a structure can be adopted in which the planar shape of the light absorption layer 31 includes a cross shape formed by disposing the light absorption layer 31 on the optical path of the incident light 22 on the surface (light receiving surface) on the side of the microlens 17 that is incident on the impurity layer 24. By the structure in which the planar shape of the light absorption layer 31 includes a cross shape, the inclined incident light 22 incident on one photoelectric conversion unit 21 can be prevented from passing through the impurity layer 24 and incident on other photoelectric conversion units 21, and the sensitivity difference between the photoelectric conversion units 21 included in the same photoelectric conversion unit group 23 can be reduced. In addition, the formation of the light absorption layer 31 can be made easier.

[0094] (2) Additionally, for example, as Figure 13 shown, a structure can be adopted in which the planar shape of the light absorption layer 31 includes a frame shape formed by disposing the light absorption layer 31 on the optical path of the incident light 22 on the surface (light receiving surface) on the side of the microlens 17 that is incident on the inter-pixel light-shielding portion 26. By the structure in which the planar shape of the light absorption layer 31 includes a frame shape, the incident light 22 can be prevented from being incident on the surface on the side of the microlens 17 of the inter-pixel light-shielding portion 26, the incident light 22 can be prevented from being scattered by the inter-pixel light-shielding portion 26, and noise (color mixing) can be prevented from being generated in the signal charges of the photoelectric conversion unit 21 due to the scattered incident light 22. In addition, the formation of the light absorption layer 31 can be made easier.

[0095] Additionally, for example, as Figure 15 shown, a structure can be adopted in which the planar shape of the light absorption layer 31 includes Figure 14 the cross shape shown in Figure 13 and the frame shape shown in

[0096] <2. Second Embodiment: Electronic Device>

[0097] Next, the electronic device 100 according to the second embodiment of the present disclosure will be described. Figure 16 is a schematic configuration diagram of the electronic device 100 according to the second embodiment of the present disclosure.

[0098] The electronic device 100 according to the second embodiment includes a solid-state imaging device 101, an optical lens 102, a shutter device 103, a drive circuit 104, and a signal processing circuit 105. In the electronic device 100 according to the second embodiment, an embodiment is shown in which the solid-state imaging device 1 according to the first embodiment of the present disclosure is used as the solid-state imaging device 101 in an electronic device (for example, a camera).

[0099] The optical lens 102 forms an image of the image light (incident light 106) from the subject on the imaging surface of the solid-state imaging device 101. As a result, signal charges are accumulated in the solid-state imaging device 101 for a certain period of time. The shutter device 103 controls the light irradiation period and the light shielding period of the solid-state imaging device 101. The drive circuit 104 supplies drive signals for controlling the transfer operation of the solid-state imaging device 101 and the shutter operation of the shutter device 103. By the drive signals (timing signals) supplied from the drive circuit 104, an operation of transferring signals to the solid-state imaging device 101 is performed. The signal processing circuit 105 performs various signal processes on the signals (pixel signals) output from the solid-state imaging device 101. The video signal that has undergone signal processing is stored in a storage medium such as a memory, or output to a monitor.

[0100] Note that the electronic device 100 to which the solid-state imaging device 1 can be applied is not limited to a camera, and the solid-state imaging device 1 can also be applied to other electronic devices. The solid-state imaging device 1 can be applied to imaging devices such as camera modules of mobile devices such as mobile phones or tablet terminals.

[0101] In addition, in the second embodiment, a configuration is adopted in which the solid-state imaging device 1 according to the first embodiment is used as the solid-state imaging device 101 in an electronic device, but other configurations can also be adopted. For example, the solid-state imaging device 1 according to the modified example can be used in an electronic device.

[0102] Note that the present technology can also adopt the following configuration.

[0103] (1) A solid-state imaging device, comprising:

[0104] A pixel unit configured such that a plurality of unit pixels are arranged in a two-dimensional array, the plurality of unit pixels being configured to include a plurality of photoelectric conversion units and a plurality of microlenses, the plurality of photoelectric conversion units being formed on a substrate and generating signal charges corresponding to the amount of incident light, the plurality of microlenses being configured such that one of the microlenses is formed for one of the plurality of photoelectric conversion unit groups, each of the photoelectric conversion unit groups being composed of at least two adjacent photoelectric conversion units, the photoelectric conversion units being insulated from each other by an impurity layer, and the plurality of microlenses guiding the incident light to each of the plurality of photoelectric conversion unit groups; and

[0105] A plurality of light absorption layers formed between the microlenses and the substrate, and absorbing a part of the incident light guided by the microlenses to the photoelectric conversion unit groups.

[0106] (2) The solid-state imaging device according to (1), wherein the light absorption layer absorbs a part of the incident light that has passed through the microlens, so that the difference between the signal charges generated by the respective photoelectric conversion units included in the same photoelectric conversion unit group becomes smaller.

[0107] (3) The solid-state imaging device according to (1) or (2), wherein the area of the planar shape of the light absorption layer is smaller than the area of the planar shape of the photoelectric conversion unit group.

[0108] (4) The solid-state imaging device according to (3), wherein the planar shape of the light absorption layer is a predetermined shape as follows: as the distance between the unit pixel in which the light absorption layer is formed and the central portion of the pixel unit becomes farther, the light absorption layer becomes longer in a direction parallel to the line passing through the unit pixel and the central portion of the pixel unit.

[0109] (5) The solid-state imaging device according to (4), wherein the planar shape is a rectangular shape.

[0110] (6) The solid-state imaging device according to (4), wherein the planar shape is an elliptical shape.

[0111] (7) The solid-state imaging device according to any one of (1) to (3), wherein the planar shape of the light absorption layer includes a cross shape formed by disposing the light absorption layer on the optical path of the incident light on the surface of the microlens side of the impurity layer.

[0112] (8) The solid-state imaging device according to any one of (1) to (3), further comprising:

[0113] An inter-pixel light-shielding portion formed between the photoelectric conversion unit groups,

[0114] wherein the planar shape of the light absorption layer includes a frame shape formed by disposing the light absorption layer on the optical path of the incident light on the surface of the microlens side of the inter-pixel light-shielding portion.

[0115] (9) The solid-state imaging device according to any one of (1) to (8), further comprising:

[0116] A color filter disposed between the photoelectric conversion unit and the microlens,

[0117] wherein the light absorption layer is formed on the surface of the microlens side of the color filter or on the surface of the substrate side of the color filter, and

[0118] The material of the light absorption layer is the same as that of any one of the color filters.

[0119] (10) The solid-state imaging device according to (9), wherein the material of the color filter is the same as the material of the light absorption layer formed in the color filter.

[0120] (11) The solid-state imaging device according to (9), wherein the material of the color filter is different from the material of the light absorption layer formed in the color filter.

[0121] (12) The solid-state imaging device according to any one of (9) to (11), wherein the thickness of the light absorption layer is less than the thickness of the color filter.

[0122] (13) The solid-state imaging device according to any one of (9) to (12), wherein as the distance between the unit pixel having the light absorption layer and the center portion of the pixel unit becomes farther, when observed in a plan view, the position of the light absorption layer with respect to the color filter becomes closer to the center portion side of the pixel unit.

[0123] (14) The solid-state imaging device according to any one of (1) to (13), wherein the microlens is configured such that, from the center portion of the pixel unit toward the outer peripheral portion of the pixel unit, when observed in a plan view, the center portion of the microlens is offset toward the center portion side of the pixel unit compared to the center of the photoelectric conversion unit group corresponding to the microlens.

[0124] (15) The solid-state imaging device according to any one of (1) to (14), further comprising:

[0125] A color filter disposed between the photoelectric conversion unit and the microlens,

[0126] wherein the color filter is configured such that, from the center portion of the pixel unit toward the outer peripheral portion of the pixel unit, when observed in a plan view, the center portion of the color filter is offset toward the center portion side of the pixel unit compared to the center of the photoelectric conversion unit group corresponding to the color filter.

[0127] (16) An electronic device, comprising:

[0128] A solid-state imaging device includes a pixel unit and a plurality of light absorption layers. The pixel unit is configured such that a plurality of unit pixels are arranged in a two-dimensional array. The plurality of unit pixels are configured to include a plurality of photoelectric conversion units and a plurality of microlenses. The plurality of photoelectric conversion units are formed on a substrate and generate signal charges corresponding to the amount of incident light. The plurality of microlenses are configured such that one microlens is formed for one of the plurality of groups of photoelectric conversion units. Each group of photoelectric conversion units is composed of at least two adjacent photoelectric conversion units. The photoelectric conversion units are insulated from each other by an impurity layer. The plurality of microlenses guide the incident light to each of the plurality of groups of photoelectric conversion units. The plurality of light absorption layers are formed between the microlenses and the substrate and absorb a part of the incident light guided to the groups of photoelectric conversion units by the microlenses;

[0129] An optical lens that forms an image of image light from a subject on an imaging surface of the solid-state imaging device; and

[0130] A signal processing circuit that performs signal processing on a signal output from the solid-state imaging device.

[0131] List of reference numerals

[0132] 1 Solid-state imaging device

[0133] 2 Substrate

[0134] 3 Pixel region

[0135] 4 Vertical drive circuit

[0136] 5 Column signal processing circuit

[0137] 6 Horizontal drive circuit

[0138] 7 Output circuit

[0139] 8 Control circuit

[0140] 9 Pixel

[0141] 10 Pixel drive line

[0142] 11 Vertical signal line

[0143] 12 Horizontal signal line

[0144] 13 Insulating film

[0145] 14 Light-shielding film

[0146] 15 Light-receiving layer

[0147] 16 Color filter

[0148] 17 Microlens

[0149] 18 Light-collecting layer

[0150] 19 Wiring layer

[0151] 20 Support substrate

[0152] 21 Photoelectric conversion unit

[0153] 21a Central-side photoelectric conversion unit

[0154] 21b Peripheral-side photoelectric conversion unit

[0155] 22 Incident light

[0156] 23 Photoelectric conversion unit group

[0157] 24 Impurity layer

[0158] 25 Groove portion

[0159] 26 Inter-pixel light-shielding portion

[0160] 27 Color filter array

[0161] 28 Microlens array

[0162] 29 Unit pixel

[0163] 30 Pixel unit

[0164] 31 Light absorption layer

[0165] 32 Optical path

[0166] 33 Region

[0167] 34 Interlayer insulating film

[0168] 35 Wiring

[0169] 100 Electronic device

[0170] 101 Solid-state imaging device

[0171] 102 Optical lens

[0172] 103 Shutter device

[0173] 104 Driving circuit

[0174] 105 Signal processing circuit

[0175] 106 Incident light

Claims

1. A solid-state imaging device, comprising: a pixel unit configured such that a plurality of unit pixels are arranged in a two-dimensional array, the plurality of unit pixels being configured to include a plurality of photoelectric conversion units and a plurality of microlenses, the plurality of photoelectric conversion units being formed on a substrate and generating signal charges corresponding to the amount of incident light, the plurality of microlenses being configured such that one of the microlenses is formed for each of a plurality of groups of photoelectric conversion units, each of the groups of photoelectric conversion units being composed of at least two adjacent photoelectric conversion units, the photoelectric conversion units being insulated from each other by an impurity layer, and the plurality of microlenses guiding the incident light to each of the plurality of groups of photoelectric conversion units; and a plurality of light absorption layers formed between the microlenses and the substrate and absorbing a part of the incident light guided to the groups of photoelectric conversion units by the microlenses, wherein the area of the planar shape of the light absorption layer is smaller than the area of the planar shape of the group of photoelectric conversion units, wherein the planar shape of the light absorption layer is a predetermined shape as follows: as the distance between the unit pixel in which the light absorption layer is formed and the central portion of the pixel unit becomes farther, the light absorption layer becomes longer in a direction parallel to the line passing through the unit pixel and the central portion of the pixel unit.

2. The solid-state imaging device according to claim 1, wherein, The planar shape is a rectangular shape.

3. The solid-state imaging device according to claim 1, wherein The planar shape is an elliptical shape.

4. The solid-state imaging device according to claim 1, wherein, The planar shape of the light absorption layer includes a cross shape formed by disposing the light absorption layer on the optical path of the incident light on the surface of the microlens side incident on the impurity layer.

5. The solid-state imaging device according to claim 1, further comprising: an inter-pixel light-shielding portion formed between the groups of photoelectric conversion units, wherein the planar shape of the light absorption layer includes a frame shape formed by disposing the light absorption layer on the optical path of the incident light on the surface of the microlens side incident on the inter-pixel light-shielding portion.

6. The solid-state imaging device according to claim 1, further comprising: a color filter disposed between the photoelectric conversion unit and the microlens, wherein the light absorption layer is formed on the surface of the color filter on the microlens side or on the surface of the color filter on the substrate side, and the material of the light absorption layer is the same as the material of any one of the color filters.

7. The solid-state imaging device according to claim 6, wherein, The material of the color filter is the same as the material of the light absorption layer formed in the color filter.

8. The solid-state imaging device according to claim 6, wherein, The material of the color filter is different from the material of the light absorption layer formed in the color filter.

9. The solid-state imaging device according to claim 6, wherein, The thickness of the light absorption layer is smaller than the thickness of the color filter.

10. The solid-state imaging device according to claim 6, wherein, As the distance between the unit pixel in which the light absorption layer is formed and the central portion of the pixel unit becomes farther, when observed in a plan view, the position of the light absorption layer relative to the color filter becomes closer to the central portion side of the pixel unit.

11. The solid-state imaging device according to claim 1, wherein, The microlens is configured such that, when viewed in a plan view from the central portion of the pixel unit toward the outer peripheral portion of the pixel unit, the central portion of the microlens is shifted toward the central portion of the pixel unit side with respect to the center of the photoelectric conversion unit group corresponding to the microlens.

12. The solid-state imaging device according to claim 1, further comprising: a color filter disposed between the photoelectric conversion unit and the microlens, wherein the color filter is configured such that, when viewed in a plan view from the central portion of the pixel unit toward the outer peripheral portion of the pixel unit, the central portion of the color filter is shifted toward the central portion of the pixel unit side with respect to the center of the photoelectric conversion unit group corresponding to the color filter.

13. An electronic device, comprising: the solid-state imaging device according to any one of claims 1 to 12; an optical lens that forms an image of image light from a subject on an imaging surface of the solid-state imaging device; and a signal processing circuit that performs signal processing on a signal output from the solid-state imaging device.

Images