Image pickup element and image pickup device

Abstract

An object of the present invention is to prevent image quality degradation by preventing incident light that has passed through a photoelectric conversion unit in a pixel from affecting a charge holding unit or an adjacent pixel, etc. The present invention provides an imaging element including a pixel, a wiring layer, and an incident light attenuation unit. Each pixel includes a photoelectric conversion unit and a pixel circuit, the photoelectric conversion unit being formed on a semiconductor substrate and performing photoelectric conversion of incident light, and the pixel circuit being used to generate an image signal corresponding to the charge generated by the photoelectric conversion. The wiring layer is arranged on a surface of the semiconductor substrate different from the surface on which the incident light is incident, and transmits an image signal or a signal to be applied to the pixel circuit. The incident light attenuation unit attenuates the incident light that has passed through the photoelectric conversion unit.

Description

Technical Field

[0001] The present technology relates to an imaging element and an imaging device. More specifically, the present technology relates to a back-illuminated imaging element and an imaging device in which a wiring layer is formed on a surface of a semiconductor substrate different from a surface on which light is incident. Background Art

[0002] Generally, among imaging elements in which pixels configured to generate image signals by photoelectrically converting incident light are arranged in a two-dimensional manner, an imaging element is used that has a wiring layer formed on the surface of a semiconductor substrate, and a photoelectric conversion unit configured to perform photoelectric conversion is formed on the surface, which is different from the surface irradiated with the incident light. This imaging element is called a back-illuminated imaging element. Since the incident light reaches the photoelectric conversion unit without being restricted by the wiring layer, the aperture ratio of the pixel can be improved. In such a pixel of the imaging element, after a predetermined exposure time, the charge generated by the above-mentioned photoelectric conversion unit is transferred to and maintained in a floating diffusion portion, which is formed in a diffusion layer of the semiconductor substrate. An image signal of a voltage corresponding to the amount of charge retained is generated, and the image signal is read out from the pixel for output.

[0003] In the above-mentioned back-illuminated imaging element, there is a problem that when light incident from the back side of the semiconductor substrate passes through the semiconductor substrate without being photoelectrically converted by the photoelectric conversion unit, the light is reflected to the semiconductor substrate side by the wiring layer arranged on the front side, etc. This reflected light may be optical noise. For example, in the case where the reflected light is incident on the photoelectric conversion unit of the adjacent pixel, the signal based on the reflected light is superimposed on the image signal of the adjacent pixel, and crosstalk is generated.

[0004] In addition, in general imaging elements, line exposure sequential readout (rolling shutter) is adopted. This is a technology that performs exposure and transmission of image signals by changing the time of each line, and the technology performs exposure sequentially by changing the start time and end time of exposure of each line while continuously reading out image signals from pixels in units of lines. Although the structure of pixels can be simplified, a phenomenon called focal plane distortion occurs, in which a high-speed moving object is deformed due to the time difference between the start and end of exposure of each line. In addition, in the case of using lighting with a very short light emission period such as a flash, a phenomenon called flash band also occurs, which causes brightness differences depending on the position on the screen. As described above, in a rolling shutter type imaging element, the image quality after imaging deteriorates.

[0005] A global shutter has been proposed as a driving method for solving this problem in the rolling shutter type. In the global shutter, a charge holding unit is arranged between the above-mentioned photoelectric conversion unit and the floating diffusion, and after all pixels are exposed at the same time, the charge generated by the photoelectric conversion is collectively transferred to and held in the charge holding unit. Thereafter, the charge transfer from the charge holding unit to the floating diffusion, the generation of the image signal, and the reading of the image signal from the pixel are sequentially performed for each row. As described above, in a global shutter type imaging element, since all pixels can be exposed at the same time, the occurrence of focal plane distortion and the like can be prevented.

[0006] Even in this global shutter type imaging element, the influence of reflected light occurs. Specifically, when reflected light is incident on an adjacent pixel, crosstalk occurs in the same manner as in a rolling shutter type. In addition, noise occurs when reflected light enters the charge retention unit of its own pixel and causes photoelectric conversion. In a global shutter type imaging element, this light leakage to the charge retention unit is managed as parasitic light sensitivity (PLS), and an extremely low PLS is required. Therefore, in order to prevent crosstalk of reflected light, etc., an imaging element has been proposed in which a shading portion is arranged in a substrate to achieve optical separation (for example, see patent document 1). With respect to this prior art, an imaging element has been proposed in which a front-side shading portion is further arranged between the charge retention unit and the wiring layer to prevent reflected light from being incident on the charge retention unit.

[0007] Reference List

[0008] Patent Literature

[0009] Patent Document 1: Japanese Patent Application Laid-Open No. 2015-228510 Summary of the invention

[0010] Problems to be solved by the present invention

[0011] In the above-mentioned image pickup element, a transistor for transferring charges generated by photoelectric conversion is arranged. In the above-mentioned light shielding portion of the prior art, an opening portion is formed in the region of the light shielding portion, and a channel region of the transistor for transferring charges is arranged in the formed opening portion. Therefore, in the prior art, there is a problem that reflected light cannot be prevented from being incident on the photoelectric conversion unit or the charge holding unit of the adjacent pixel through the opening portion of the light shielding portion, and the image quality of the image signal is deteriorated.

[0012] The present technology has been made in view of the above-mentioned problem points, and an object of the present technology is to reduce the incidence of incident light transmitted through a photoelectric conversion unit in a pixel onto a charge holding unit or an adjacent pixel or the like and prevent image quality from being deteriorated.

[0013] Technical solutions to the problem

[0014] The present technology is made to eliminate the above-mentioned problem points, and the first aspect of the present technology is an imaging element, which includes: a pixel, the pixel includes a photoelectric conversion unit and a pixel circuit, the photoelectric conversion unit is formed in a semiconductor substrate and performs photoelectric conversion based on incident light, and the pixel circuit generates an image signal according to the charge generated by the photoelectric conversion; a wiring layer, the wiring layer is arranged on a surface of the semiconductor substrate different from the surface on which the incident light is incident, and transmits the image signal or the signal applied to the pixel circuit; and an incident light attenuation unit, the incident light attenuation unit attenuates the incident light passing through the photoelectric conversion unit. This brings about the effect of the incident light attenuation unit attenuating the incident light passing through the photoelectric conversion unit. It is expected to reduce the optical noise based on the incident light passing through the photoelectric conversion unit.

[0015] Furthermore, in the first aspect, the incident light attenuating unit may include: a cover having an opening portion, the opening portion being arranged between the semiconductor substrate and the wiring layer and allowing light transmitted through the photoelectric conversion unit to be incident; and a wall portion surrounding the opening portion. This brings about the effect that the incident light attenuating unit is formed by the cover and the wall portion.

[0016] Furthermore, in the first aspect, the incident light attenuating unit may include the wall portion formed simultaneously with the wiring layer. This brings about the effect that the wall portion of the incident light attenuating unit is formed simultaneously with the wiring layer.

[0017] Furthermore, in the first aspect, the incident light attenuating unit may further include a bottom portion, the bottom portion being adjacent to the wall portion and arranged to face the cover portion. This results in the cover portion, the wall portion, and the bottom portion forming the incident light attenuating unit.

[0018] Furthermore, in the first aspect, the incident light attenuating unit may include the bottom formed simultaneously with the wiring layer. This brings about the effect that the bottom of the incident light attenuating unit is formed simultaneously with the wiring layer.

[0019] Furthermore, in the first aspect, the opening portion may be arranged in the incident light attenuating unit at a position shifted according to the incident angle of the incident light. This brings about the effect of adjusting the position of the opening portion of the incident light attenuating unit according to the incident angle of the incident light incident on the pixel.

[0020] Furthermore, in the first aspect, the pixel circuit may include: a charge holding unit that holds the generated charge; and an image signal generating unit that generates an image signal based on the held charge. This brings about the effect of generating an image signal corresponding to the charge held in the charge holding unit.

[0021] Furthermore, the first aspect may further include a light shielding wall which is arranged between the photoelectric conversion unit and the charge holding unit and shields the incident light. This brings about the effect of shielding light between the photoelectric conversion unit and the charge holding unit.

[0022] In addition, the first aspect may further include a shielding film arranged near the charge holding unit on the surface of the semiconductor substrate where the incident light is incident, and shielding the incident light. This brings about the effect of shielding the charge holding unit from incident light.

[0023] In addition, the second aspect of the present technology is an imaging device including: a pixel including a photoelectric conversion unit and a pixel circuit, the photoelectric conversion unit being formed in a semiconductor substrate and performing photoelectric conversion based on incident light, the pixel circuit generating an image signal based on the charge generated by the photoelectric conversion; a wiring layer arranged on a surface of the semiconductor substrate different from the surface on which the incident light is incident, and transmitting the image signal or a signal applied to the pixel circuit; an incident light attenuation unit attenuating the incident light passing through the photoelectric conversion unit; and a processing circuit processing the transmitted image signal. This brings about the effect of the incident light attenuation unit attenuating the incident light passing through the photoelectric conversion unit. It is expected to reduce the optical noise based on the incident light passing through the photoelectric conversion unit.

[0024] Effects of the Invention

[0025] According to the present technology, a significant effect of reducing the incidence of incident light transmitted through the photoelectric conversion unit in the pixel onto the charge holding unit or an adjacent pixel or the like and preventing image quality degradation is exhibited. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a diagram illustrating a configuration example of an image pickup element according to an embodiment of the present technology.

[0027] Figure 2 is a diagram illustrating a circuit configuration example of a pixel according to the first embodiment of the present technology.

[0028] Figure 3 is a diagram illustrating a configuration example of a pixel according to the first embodiment of the present technology.

[0029] Figure 4 is a diagram illustrating a configuration example of a pixel according to the first embodiment of the present technology.

[0030] Figure 5 It is a diagram illustrating a method of manufacturing an image pickup element according to the first embodiment of the present technology.

[0031] Figure 6 It is a diagram illustrating a method of manufacturing an image pickup element according to the first embodiment of the present technology.

[0032] Figure 7 It is a diagram illustrating a method of manufacturing an image pickup element according to the first embodiment of the present technology.

[0033] Figure 8 It is a diagram illustrating a method of manufacturing an image pickup element according to the first embodiment of the present technology.

[0034] Fig. 9 It is a diagram illustrating a method of manufacturing an image pickup element according to the first embodiment of the present technology.

[0035] Fig.10 It is a diagram illustrating a method of manufacturing an image pickup element according to the first embodiment of the present technology.

[0036] Fig.11 is a diagram illustrating a configuration example of an incident light attenuating unit according to a first modification example of the first embodiment of the present technology.

[0037] Fig.12 is a diagram illustrating a configuration example of an incident light attenuating unit according to a second modification example of the first embodiment of the present technology.

[0038] Fig.13 2 is a diagram illustrating a method of manufacturing an image pickup element according to a second embodiment of the present technology.

[0039] Fig.14 2 is a diagram illustrating a method of manufacturing an image pickup element according to a second embodiment of the present technology.

[0040] Fig.15 It is a diagram illustrating a method of manufacturing an image pickup element according to a third embodiment of the present technology.

[0041] Fig.16 It is a diagram illustrating a method of manufacturing an image pickup element according to a third embodiment of the present technology.

[0042] Fig.17 is a diagram illustrating a circuit configuration example of a pixel according to a fourth embodiment of the present technology.

[0043] Fig.18is a diagram illustrating a configuration example of a pixel according to a fourth embodiment of the present technology.

[0044] Fig.19 is a diagram illustrating a configuration example of a pixel according to a fifth embodiment of the present technology.

[0045] Fig. 20 : is a block diagram illustrating a schematic configuration example of a camera as an example of an image pickup device to which the present technology can be applied. DETAILED DESCRIPTION

[0046] Next, a method for implementing the present technology (hereinafter referred to as an embodiment) will be described with reference to the accompanying drawings. In the following drawings, the same or similar parts are represented by the same or similar reference numerals. However, the drawings are schematic, and the size ratios of the various units, etc. do not always match the actual size ratios. In addition, it is needless to say that the drawings respectively include parts having different size relationships and ratios between the various drawings. In addition, the embodiments will be described in the following order.

[0047] 1. First Embodiment

[0048] 2. Second Embodiment

[0049] 3. Third embodiment

[0050] 4. Fourth embodiment

[0051] 5. Fifth embodiment

[0052] 6. Camera application examples

[0053] <1. First Embodiment>

[0054] [Structure of the imaging element]

[0055] Figure 1 is a diagram illustrating a configuration example of an image pickup element according to an embodiment of the present technology. Figure 1 The image pickup element 1 in the embodiment includes a pixel array unit 10 , a vertical driving unit 20 , a column signal processing unit 30 , and a control unit 40 .

[0056] The pixel array unit 10 is constructed in a manner that the pixels 100 are arranged in a two-dimensional grid. Here, the pixel 100 generates an image signal according to the irradiated light. The pixel 100 includes a photoelectric conversion unit for generating a charge according to the irradiated light. In addition, the pixel 100 also includes a pixel circuit. The pixel circuit generates an image signal based on the charge generated by the photoelectric conversion unit. The generation of the image signal is controlled by a control signal generated by a vertical drive unit 20 described later. In the pixel array unit 10, signal lines 11 and 12 are arranged in an XY matrix. The signal line 11 is a signal line for transmitting a control signal for a pixel circuit in the pixel 100, and is arranged for each row of the pixel array unit 10 in a manner that is commonly wired to the pixels 100 arranged in each row. The signal line 12 is a signal line for transmitting an image signal generated by the pixel circuit of the pixel 100, and is arranged for each column of the pixel array unit 10 in a manner that is commonly wired to the pixels 100 arranged in each column. These photoelectric conversion units and pixel circuits are formed in a semiconductor substrate.

[0057] The vertical driving unit 20 generates a control signal for the pixel circuit of the pixel 100. The vertical driving unit 20 generates a control signal for the pixel circuit of the pixel 100. Figure 1 The signal line 11 in the column transmits the generated control signal to the pixel 100. The column signal processing unit 30 processes the image signal generated by the pixel 100. The column signal processing unit 30 processes the image signal generated by the pixel 100. Figure 1 The column signal processing unit 30 processes the image signal transmitted from the pixel 100 via the signal line 12 in the column signal processing unit. The processing in the column signal processing unit 30 corresponds to, for example, analog-to-digital conversion for converting the analog image signal generated in the pixel 100 into a digital image signal. The image signal processed by the column signal processing unit 30 is output as the image signal of the image pickup element 1. The control unit 40 controls the entire image pickup element 1. The control unit 40 controls the image pickup element 1 by generating and outputting a control signal for controlling the vertical drive unit 20 and the column signal processing unit 30. The control signal generated by the control unit 40 is transmitted to the vertical drive unit 20 and the column signal processing unit 30 through the signal lines 41 and 42, respectively. It is to be noted that the column signal processing unit 30 is an example of a processing circuit described in the claims. The image pickup element 1 is an example of an image pickup device described in the claims.

[0058] [Pixel Circuit Structure]

[0059] Figure 2 is a diagram illustrating a circuit configuration example of a pixel according to the first embodiment of the present technology. Figure 2 is a circuit diagram showing the structure of the pixel 100 . Figure 2The pixel 100 in the embodiment includes a photoelectric conversion unit 101, a first charge holding unit 102, a second charge holding unit 103, and metal oxide semiconductor (MOS) transistors 105 to 109. In addition, signal lines TR1, TR2, RST, SEL, and OUT are connected in the pixel 100. The signal lines TR1, TR2, RST, and SEL are signal lines for transmitting control signals of the pixel 100. These signal lines are connected to the gates of the MOS transistors. When a voltage equal to or higher than a threshold value between the gate and the source is applied to the MOS transistor via these signal lines, the applied MOS transistor can be turned on. The signal lines TR1, TR2, RST, and SEL constitute the signal line 11. At the same time, the signal line OUT constitutes the signal line 12, and transmits the image signal generated by the pixel 100. In addition, the power line Vdd is connected to the pixel 100, and the power is supplied to the pixel 100.

[0060] The anode of the photoelectric conversion unit 101 is grounded, and the cathode thereof is connected to the source of the MOS transistor 105. The drain of the MOS transistor 105 is connected to the source of the MOS transistor 106 and one end of the first charge holding unit 102. The other end of the first charge holding unit 102 is grounded. The gate of the MOS transistor 105 is connected to the signal line TR1, and the gate of the MOS transistor 106 is connected to the signal line TR2. The drain of the MOS transistor 106 is connected to the source of the MOS transistor 107, the gate of the MOS transistor 108, and one end of the second charge holding unit 103. The other end of the second charge holding unit 103 is grounded. The gate of the MOS transistor 107 is connected to the signal line RST. The drains of the MOS transistors 107 and 108 are commonly connected to the power supply line Vdd, and the source of the MOS transistor 108 is connected to the drain of the MOS transistor 109. The source of the MOS transistor 109 is connected to the signal line OUT, and the gate thereof is connected to the signal line SEL.

[0061] As described above, the photoelectric conversion unit 101 generates and holds charges according to the irradiated light. A photodiode can be used for the photoelectric conversion unit 101. The MOS transistor 105 is a transistor for transferring the charge generated by the photoelectric conversion of the photoelectric conversion unit 101 to the first charge holding unit 102. The charge transfer in the MOS transistor 105 is controlled by a signal transmitted through the signal line TR1. The first charge holding unit 102 is a capacitor for holding the charge transferred by the MOS transistor 105. The MOS transistor 106 is a transistor for transferring the charge held in the first charge holding unit 102 to the second charge holding unit 103. The charge transfer in the MOS transistor 106 is controlled by a signal transmitted through the signal line TR2. It should be noted that a floating diffusion formed in a diffusion layer of a semiconductor substrate can be used for the second charge holding unit 103.

[0062] The MOS transistor 108 is a transistor for generating a signal based on the charge held in the second charge holding unit 103. The MOS transistor 109 is a transistor for outputting the signal generated by the MOS transistor 108 to the signal line OUT as an image signal. The MOS transistor 108 is controlled by a signal transmitted through the signal line SEL. In addition, the MOS transistors 108 and 109 constitute an image signal generating unit 110.

[0063] The MOS transistor 107 is a transistor for resetting the second charge holding unit 103 by discharging the charge held in the second charge holding unit 103 to the power supply line Vdd. The resetting by the MOS transistor 107 is controlled by a signal transmitted through the signal line RST. At the time of the resetting, the photoelectric conversion unit 101 and the first charge holding unit 102 can be reset at the same time by turning on the MOS transistors 105 and 106. It is to be noted that the first charge holding unit 102, the second charge holding unit 103, and the MOS transistors 105 to 109 constitute the pixel circuit 120. In addition, the first charge holding unit 102 and the second charge holding unit 103 are examples of the charge holding units described in the claims.

[0064] It can be done as follows Figure 2An image signal is generated in the pixel 100. First, MOS transistors 105 to 107 are turned on to reset the photoelectric conversion unit 101. Next, after a predetermined time has passed, MOS transistors 106 and 107 are turned on to reset the first charge holding unit 102. After completing the reset, MOS transistor 105 is turned on. As a result, the charge generated in the photoelectric conversion unit 101 is transferred to and held in the first charge holding unit 102. This operation of charge transfer from the reset of the photoelectric conversion unit 101 to the MOS transistor 105 is performed simultaneously in all pixels 100 arranged in the pixel array unit 10. With this configuration, a global shutter is realized. It should be noted that the period from the reset of the photoelectric conversion unit 101 to the charge transfer of the MOS transistor 105 corresponds to the exposure period.

[0065] Next, the MOS transistor 107 is turned on to reset the second charge holding unit 103. Next, the MOS transistor 106 is turned on to transfer the charge held in the first charge holding unit 102 to the second charge holding unit 103 and to make the second charge holding unit 103 hold the transferred charge. Subsequently, the MOS transistor 108 generates an image signal based on the charge held in the second charge holding unit 103. Next, by turning on the MOS transistor 109, the image signal generated by the MOS transistor 108 is output to the signal line OUT. This operation from the resetting of the second charge holding unit 103 to the output of the image signal is sequentially performed for each group of pixels 100 arranged in the row of the pixel array unit 10. By outputting the image signals of the pixels 100 in all the rows of the pixel array unit 10, a frame containing image signals constituting one screen can be generated.

[0066] By simultaneously exposing all pixels 100 of the pixel array unit 10 in this manner, the occurrence of frame distortion can be prevented and the image quality can be improved. As described above, when image capture using the global shutter technique is performed, the first charge holding unit 102 is used to temporarily hold the charge generated by the photoelectric conversion unit 101. In addition, since the second charge holding unit 103 is reset to transfer the charge from the first charge holding unit 102 to the second charge holding unit 103 immediately before the MOS transistors 108 and 109 generate an image signal and output the image signal from the pixel 100, the error caused by the current (dark current) flowing into the second charge holding unit 103 can be reduced.

[0067] [Structure of the imaging element]

[0068] Figure 3 is a diagram illustrating a configuration example of a pixel according to the first embodiment of the present technology. Figure 31 is a cross-sectional view showing an example of the configuration of the pixel 100. The pixel 100 includes a support substrate 180, a wiring region composed of an insulating layer 130 and a wiring layer 131, a semiconductor substrate 140, an insulating film 152, a color filter 153, and an on-chip lens 154. Note that Figure 3 The imaging element 1 in illustrative embodiment corresponds to a back-illuminated imaging element that is irradiated with incident light from the back side (a surface different from the surface where the wiring region is formed) of the semiconductor substrate 140 .

[0069] The semiconductor substrate 140 is a substrate made of semiconductor, on which a reference Figure 1 The semiconductor parts of the photoelectric conversion unit and the pixel circuit of the pixel 100 described above are shown in FIG. 1 . In addition, the semiconductor parts of the vertical driving unit 20, the column signal processing unit 30, and the control unit 40 are also formed on the semiconductor substrate 140. A p-type well region is formed on the semiconductor substrate 140, and the photoelectric conversion unit of the pixel 100 and the like are formed in the well region. For convenience, it is assumed that the semiconductor substrate 140 constitutes the well region. Figure 3 The photoelectric conversion unit 101 , the first charge holding unit 102 , and the MOS transistor 105 are described.

[0070] The photoelectric conversion unit 101 is composed of an n-type semiconductor region 141 and a surrounding p-type well region. Photoelectric conversion is performed by a pn junction at the interface between these n-type semiconductor region 141 and the p-type well region. Electrons among the charges generated by this photoelectric conversion are held in the n-type semiconductor region 141. The held electrons are held by referring to Figure 2 The described MOS transistor 105 is transferred to the first charge holding unit 102. It should be noted that a p-type semiconductor region 143 is arranged on the front side of the n-type semiconductor region 141. The p-type semiconductor region is a region for pinning the surface order of the semiconductor substrate 140. The second charge holding unit 102 is composed of an n-type semiconductor region 142. A p-type semiconductor region 144 for pinning is also formed on the front side of the n-type semiconductor region 142. The MOS transistor 105 is a MOS transistor in which the n-type semiconductor regions 141 and 142 are used as a source region and a drain region, respectively, and a p-type well region between the n-type semiconductor regions 141 and 142 is used as a channel region. In addition, in the MOS transistor 105, a gate 145 is arranged by inserting an insulating film.

[0071] The separation region 151 is arranged between the photoelectric conversion unit 101 and the first charge holding unit 102. Specifically, the separation region 151 is formed in the semiconductor substrate 140 between the n-type semiconductor regions 141 and 142. This separation region 151 is composed of, for example, an insulator, and prevents the movement of charges between the photoelectric conversion unit 101 and the charge holding unit 102. It is to be noted that the separation region 151 may also be arranged between the pixels 100.

[0072] A light shielding wall 163 may be arranged in the separation region 151 around the photoelectric conversion unit 101. The light shielding wall 163 blocks incident light of the pixel 100 and stray light to be described later from being incident on the first charge holding unit 102. In addition, the light shielding wall 163 also prevents stray light from being incident on adjacent pixels 100. For example, the light shielding wall 163 may be composed of a metal such as tungsten (W), aluminum (Al), and copper (Cu).

[0073] The wiring region is a region where the wiring layer 131 and the insulating layer 130 are formed. The wiring layer 131 is a wiring for transmitting an image signal generated in the pixel 100 and a control signal for controlling the pixel circuit. Figure 1 The signal lines 11 and 12 are described as being composed of a wiring layer 131. The wiring layer 131 may be composed of a metal such as copper (Cu). The insulating layer 130 insulates the wiring layer 131. For example, the insulating layer 130 may be composed of an oxide such as silicon oxide (SiO2). The wiring layer 131 may be constructed as a multilayer. Figure 3 1 shows an example of a wiring layer having a three-layer structure. The wiring layers 131 arranged in different layers may be connected by via plugs 133. In addition, the elements formed on the semiconductor substrate 140 and the wiring layer 131 may be connected by contact plugs. Figure 3 In the embodiment, the gate 145 of the MOS transistor 105 is connected to the wiring layer 131 through the contact plug 132. Note that the wiring layer 131, the contact plug 132, and the via plug 133 are examples of the wiring layer described in the claims.

[0074] The on-chip lens 154 is a lens for collecting light from a subject. The color filter 153 is a filter for transmitting light of a predetermined wavelength among the light collected by the on-chip lens 154. For example, a color filter 153 for transmitting any one of red light, green light, and blue light can be used for the color filter 153. The insulating film 152 is a film for insulating the semiconductor substrate 140. An oxide film such as SiO2 can be used for the insulating film 152. The supporting substrate 180 is a substrate for supporting the semiconductor substrate 140 and the like during the manufacturing steps of the imaging element 1. A silicon wafer can be used for the supporting substrate 180.

[0075] A light shielding film 161 may be arranged in the insulating film 152. The light shielding film 161 is a film for preventing light from being incident on a region other than the photoelectric conversion unit 101 in the pixel 100. The light shielding film 161 may be composed of, for example, W, Al, and Cu. Note that an opening 162 is formed in a region of the light shielding film 161 adjacent to the photoelectric conversion unit 101 so that incident light on the photoelectric conversion unit 101 can be transmitted.

[0076] In the above-mentioned pixel 100, light from the subject is incident on the n-type semiconductor region 141 of the photoelectric conversion unit 101 via the on-chip lens 154 or the like. A portion of the light passes through the n-type semiconductor region 141 without contributing to the photoelectric conversion. This transmitted light is sometimes reflected by the wiring layer 131 or the like and is incident on the semiconductor substrate 140 again. Hereinafter, this light is referred to as stray light. This stray light becomes optical noise. For example, when stray light is incident on the first charge holding unit 102 or the like, photoelectric conversion is caused by the stray light, and the generated charge is added to the charge held in the first charge holding unit 102. Therefore, an error is generated in the image signal generated by the pixel 100, and the error becomes noise. In the imaging element of the global shutter technology, since the charge holding time of the first charge holding unit 102 is relatively long, the influence of the stray light is large, and the parasitic light sensitivity (PLS: arasitic light sensitivity) is reduced. In addition, when the stray light is incident on the adjacent pixel 100, crosstalk is generated. This is a phenomenon in which an image signal changes due to the incidence of light other than the light from the subject, such as stray light, and is a cause of noise in the image signal.

[0077] In order to prevent the stray light from being incident on the first charge holding unit 102, Figure 3 An incident light attenuation unit 170 is arranged in the pixel 100 in the photoelectric conversion unit 101. The incident light attenuation unit 170 attenuates the incident light passing through the photoelectric conversion unit 101, and is composed of a cover 171, a wall 173, and a bottom 174. The cover 171, the wall 173, and the bottom 174 are all films capable of shielding light, and can be composed of, for example, metals. Specifically, the cover 171, etc. can be composed of metals such as Al, silver (Ag), gold (Au), Cu, platinum (Pt), molybdenum (Mo), chromium (Cr), titanium (Ti), nickel (Ni), W, and iron (Fe), semiconductors such as silicon (Si), germanium (Ge), and tellurium (Te), and alloys thereof. In addition, a stacked structure of these metals, etc. can be adopted. In addition, the cover 171, etc. can have a structure in which the film thickness depends on the light shielding ability of the material used. For example, when W is used for the cover 171, etc., the cover 171, etc. can be formed with a film thickness of 200nm. At this time, a Ti film may also be arranged as a base of W. In this case, the Ti film serves as an adhesion layer.

[0078] The cover 171 has an opening 172 that is arranged adjacent to the photoelectric conversion unit 101 and transmits light that passes through the photoelectric conversion unit 101. The wall 173 is arranged adjacent to the cover 171 and is also arranged to surround the opening 172. The bottom 174 is arranged adjacent to the wall 173. In this way, the incident light attenuation unit 170 is formed as a closed area except for the opening 172 by the cover 171, the wall 173, and the bottom 174. An insulator is arranged in the closed area. Figure 3 170, the insulating layer 130 is arranged in this region. The light that has been incident on the incident light attenuation unit 170 via the opening portion 172 is attenuated while being repeatedly reflected by the cover portion 171, the wall portion 173, and the bottom portion 174. That is, the light that has passed through the photoelectric conversion unit 101 is converted into heat energy in the incident light attenuation unit 170 and is attenuated. Figure 3 This state is indicated by the bold arrow in . Therefore, the generation of stray light can be prevented, and the stray light can be blocked from being incident on the first charge holding unit 102 and the like.

[0079] Please note that Figure 3 The cover portion 171 in the embodiment is arranged between the semiconductor substrate 140 and the wiring region by being inserted in the insulating layer 130 to constitute the incident light attenuation unit 170. In addition, Figure 3 The cover portion 171 in the cover portion 171 can be arranged to cover the entire area of ​​the pixel 100. This prevents stray light from being incident on the first charge holding unit 102 and the like. At this time, the above-mentioned contact plug 132 is arranged in the opening portion 175 formed in the cover portion 171. By reducing the size of the opening portion 175, the light shielding property of the first charge holding unit 102 can be improved. It should be noted that the configuration of the incident light attenuation unit 170 is not limited to this example. For example, the bottom portion 174 can be omitted so that a part of the wiring 131 is used as the bottom portion.

[0080] [Pixel structure]

[0081] Figure 4 is a diagram illustrating a configuration example of a pixel according to the first embodiment of the present technology. Figure 4 is a plan view showing the structure of the pixel 100 as viewed from the back side, and is a reference Figure 3 FIG. 1 is a diagram showing an example of the arrangement of the photoelectric conversion unit 101, the first charge holding unit 102, the second charge holding unit 103, and the MOS transistors 105 to 109. Note that, Figure 3 Corresponding to along Figure 4 A cross-sectional view taken along the line A-A' in FIG. Figure 4, the solid rectangle represents the opening 162 of the light shielding film 161, and the dotted rectangle represents the opening 172 of the cover 171. The double-dashed line represents the position of the wall 173. In the dotted rectangle, the region hatched with oblique lines represents the gate of the MOS transistor, and the region other than the hatched region represents the n-type semiconductor region formed in the semiconductor substrate 140.

[0082] The photoelectric conversion unit 101 is arranged at the lower left of the pixel 100. The gate and drain regions of the MOS transistor 105 are sequentially arranged adjacent to the right side of the photoelectric conversion unit 101. The gate and drain regions of the MOS transistor 106 are sequentially arranged adjacent to the drain region of the MOS transistor 105. Here, the drain region of the MOS transistor 105 corresponds to the source region of the MOS transistor 106, and also constitutes the first charge holding unit 102. The gate and drain regions of the MOS transistor 107 are sequentially arranged adjacent to the drain region of the MOS transistor 106. Here, the drain region of the MOS transistor 106 corresponds to the source region of the MOS transistor 107, and also constitutes the second charge holding unit 103.

[0083] The gate and source regions of the MOS transistor 108 are sequentially arranged adjacent to the drain region of the MOS transistor 107. Here, the drain region of the MOS transistor 107 corresponds to the drain region of the MOS transistor 108. The gate and source regions of the MOS transistor 109 are sequentially arranged adjacent to the source region of the MOS transistor 108. Here, the source region of the MOS transistor 108 corresponds to the drain region of the MOS transistor 109.

[0084] like Figure 4 As shown in FIG. 1 , the light shielding wall 163 is arranged in the separation region 151 around the n-type semiconductor region 141 of the photoelectric conversion unit 101. That is, the n-type semiconductor region 141 is surrounded by the light shielding wall 163 and has a shape closed by the light shielding film 161 and the cover 171, the wall 173 and the bottom 174. In addition, the opening 172 of the cover 171 is formed close to the central part of the n-type semiconductor region 141 of the photoelectric conversion unit 101. At this time, by arranging the on-chip lens 154 at the position of collecting incident light in the central part of the n-type semiconductor region 141, the incident light transmitted through the photoelectric conversion unit 101 can be guided to the incident light attenuation unit 170. Then, the light transmitted through the photoelectric conversion unit 101 is sealed and attenuated by the incident light attenuation unit 170 having no exit except the opening 172. Therefore, it is possible to prevent stray light from being incident on the first charge holding unit 102 and the second charge holding unit 103. In addition, the influence of stray light generated by the adjacent pixel 100 can also be eliminated. Please note that Figure 4The gates of the MOS transistors 105 to 109 in the embodiment are connected to contact plugs formed in openings (not shown) formed in the cover portion 171 .

[0085] [Method for manufacturing pixel]

[0086] Figures 5 to 10 1 is a diagram illustrating a method for manufacturing an image pickup element according to a first embodiment of the present technology. First, n-type semiconductor regions 141 and 142 are formed in a semiconductor substrate 140 by ion implantation. Next, after forming an insulating layer 301 as a gate oxide film, a gate 145 is formed. An insulating layer with a sidewall shape is formed on the gate 145, and p-type semiconductor regions 143 and 144 ( Figure 5 Next, the insulating layer 302 and the cover portion 171 are sequentially stacked. This stacking can be performed by chemical vapor deposition (CVD) or sputtering. Next, the opening portion 172 ( Figure 5 b). Next, an insulating layer 303 is formed, and a trench 304 is formed by, for example, dry etching ( Figure 5 c) in.

[0087] Next, the metal film 306 constituting the cover portion 171 is constructed. At this time, the metal film 306 is also arranged in the groove 304 of the insulating layer 303 ( Figure 6 Next, the bottom 174 and the wall 173 are simultaneously formed by patterning the metal film 306 ( Figure 6 Next, an insulating layer 307 is formed, and an opening 308 reaching the gate electrode 145 is formed ( Figure 6 Next, a metal film 309 is formed, which is a material of the contact plug 132 such as W. At this time, the metal film 309 is arranged inside the opening 308 ( Figure 7 Next, the metal film 309 on the outer surface is removed by, for example, chemical mechanical polishing (CMP) to form a contact plug 132 ( Figure 7 Next, the insulating layer 310 is constructed as a film, and an opening 311 is formed at a position where the wiring layer 131 of the first layer is to be arranged ( Figure 7 i) in the text box.

[0088] Next, the metal layer 312 constituting the wiring layer 131 is constructed as a film. Cu or the like can be used for the metal layer 312, and the metal layer 312 can be formed by electroplating ( Figure 8Next, the metal layer 312 is polished by CMP to form the wiring layer 131 ( Figure 8 Thereafter, the film construction of the insulating layer and the wiring layer is repeated to form a wiring region ( Figure 8 Next, the support substrate 180 is bonded to the outer surface of the insulating layer 130, and the semiconductor substrate 140 is turned upside down to grind and thin the semiconductor substrate 140 ( Fig. 9 Next, a trench 313 is formed in the semiconductor substrate 140 ( Fig. 9 Next, an insulating film is formed on the side surface and the bottom surface of the groove 313 to form a separation region 151, and a metal film 314 is formed and embedded in the separation region 151. At the same time, an insulating film 152 ( Fig.10 Next, the metal film 314 is etched to form the opening 162. As a result, the light shielding film 161 and the light shielding wall 163 can be formed at the same time. Next, the insulating film 152 ( Fig.10 Thereafter, the color filter 153 and the on-chip lens 154 are formed, whereby the image pickup element 1 can be manufactured.

[0089] [First Modification]

[0090] Although the above-described image pickup element 1 uses the cover portion 171 including the opening portion 172 having a rectangular shape, the shape of the opening portion 172 may be changed according to the intensity of incident light or the like.

[0091] Fig.11 : is a diagram illustrating a configuration example of an incident light attenuating unit according to a first modification example of the first embodiment of the present technology. Fig.11 In FIG. 1 , a shows an example of a cover portion 171 including an opening portion 172 having a rectangular shape. Similarly, the cross-sectional shape of the wall portion 173 may be formed into a rectangular shape. Fig.11 In FIG. 1 , b and c respectively represent examples of the opening portion 172 having a circular shape and an elliptical shape. In addition, Fig.11 d in FIG. 1 represents an example of the opening portion 172 having an octagonal shape.

[0092] [Second Modification]

[0093] Although the above-described image pickup element 1 uses the cover portion 171 or the like formed of a light shielding material, a film for preventing reflection may be disposed.

[0094] Fig.12 is a diagram illustrating a configuration example of an incident light attenuating unit according to a second modification example of the first embodiment of the present technology. Fig.12The incident light attenuation unit 170 in the embodiment further includes anti-reflection films 176 and 177. The anti-reflection film 176 is laminated on the cover 171, and the anti-reflection film 177 is laminated on the bottom 174. For example, these anti-reflection films 176 and 177 can be made of Ti or the like. By laminating the anti-reflection films 176 and 177 to a thickness of one-quarter of the expected wavelength of the transmitted light from the photoelectric conversion unit 101, the light incident on the anti-reflection film 176 or the like and the light reflected from the cover 171 or the like cancel each other, so that the reflected light can be reduced. The anti-reflection film 176 or the like can have a structure with a thickness of 60 nm, for example.

[0095] As described above, since the image pickup element 1 according to the first embodiment of the present technology includes the incident light attenuation unit 170 composed of the cover portion 171 having the opening portion 172, the wall portion 173, and the bottom portion 174, the incident light transmitted through the photoelectric conversion unit 101 can be attenuated. Therefore, stray light can be prevented from being incident on the first charge holding unit 102 and the like, and noise in the image signal can be reduced. In addition, stray light can be prevented from being incident on the adjacent pixel 100, and the occurrence of crosstalk can be prevented. As described above, the light transmitted through the photoelectric conversion unit 101 can be reduced from being incident on the charge holding unit and the adjacent pixel and the like, and image quality degradation can be prevented.

[0096] <2. Second Embodiment>

[0097] In the image pickup element 1 according to the first embodiment described above, after the incident light attenuating unit 170 is formed in the wiring region, the wiring layer 131 is formed. In contrast, the image pickup element 1 according to the second embodiment of the present technology is different from the first embodiment described above in that the wall portion and the bottom portion in the incident light attenuating unit are formed simultaneously with the wiring layer.

[0098] [Method for manufacturing pixel]

[0099] Fig.13 and Fig.14 1 is a diagram illustrating a method for manufacturing an image pickup element according to a second embodiment of the present technology. Fig.13 As shown in a, a contact plug 132 is formed inside the insulating layer 130 ( Fig.13 Next, a trench 315 is formed in the insulating layer 130 ( Fig.13 Next, an opening portion 316 is formed in a region where the wiring layer 131 and the bottom portion 174 are to be arranged ( Fig.13 Next, a metal film 317 ( Fig.14 d) Next, the metal film 317 is polished by, for example, CMP to form the wiring layer 131, the wall portion 173, and the bottom portion 174.

[0100] The configuration of the image pickup element 1 other than the above-described configuration is similar to that of the image pickup element 1 described in the first embodiment of the present technology, and thus a description thereof will be omitted.

[0101] As described above, the image pickup element 1 according to the second embodiment of the present technology can simplify the method of manufacturing the image pickup element 1 by forming the wall portion 173 and the bottom portion 174 simultaneously with the wiring layer 131 .

[0102] <3. Third embodiment>

[0103] In the image pickup element 1 according to the first embodiment described above, after the incident light attenuating unit 170 is formed in the wiring region, the wiring layer 131 is formed. In contrast, the image pickup element 1 according to the third embodiment of the present technology is different from the first embodiment described above in that the bottom portion in the incident light attenuating unit 170 is formed simultaneously with the wiring layer.

[0104] [Method for manufacturing pixel]

[0105] Fig.15 and Fig.16 1 is a diagram illustrating a method for manufacturing an image pickup element according to a third embodiment of the present technology. Fig.15 As shown in a, after the cover portion 171 is formed, the insulating layer 130 ( Fig.15 Next, an opening 318 and a groove 319 are formed at a position where the contact plug 132 and the wall portion 173 are to be arranged ( Fig.15 b). Next, a metal film 320 ( Fig.15 Next, the metal film 320 is polished by CMP or the like to form the contact plug 132 and the wall portion 173 ( Fig.16 Next, the insulating layer 321 is structured as a film, and an opening portion 322 is formed at a position where the wiring layer 131 and the bottom portion 174 are to be arranged ( Fig.16 e in the figure). Next, the wiring layer 131 and the bottom portion 174 are formed. This formation can be performed by, for example, constructing a metal film by electroplating or the like and polishing the constructed metal film by CMP or the like. Fig.16 f). As mentioned above, in Fig.15 and Fig.16 In the manufacturing method, the contact plug 132 and the wall portion 173 are formed at the same time, and the wiring layer 131 and the bottom portion 174 are formed at the same time.

[0106] The configuration of the image pickup element 1 other than the above-described configuration is similar to that of the image pickup element 1 described in the first embodiment of the present technology, and thus a description thereof will be omitted.

[0107] As described above, the image pickup element 1 according to the third embodiment of the present technology can simplify the method of manufacturing the image pickup element 1 by forming the wall portion 173 simultaneously with the contact plug 132 .

[0108] <4. Fourth embodiment>

[0109] The image pickup element 1 according to the first embodiment described above performs global shutter imaging. In contrast, the image pickup element 1 according to the fourth embodiment of the present technology is different from the first embodiment described above in that rolling shutter imaging is performed.

[0110] [Pixel Circuit Structure]

[0111] Fig.17 is a diagram illustrating an example of a circuit configuration of a pixel according to a fourth embodiment of the present technology. Figure 2 , Fig.17 is a circuit diagram showing the structure of the pixel 100 . Fig.17 The pixel 100 in the reference Figure 2 The pixel 100 described is different in that the MOS transistor 106 and the second charge holding unit 103 are omitted.

[0112] exist Fig.17 , the drain of the MOS transistor 105 is connected to the source of the MOS transistor 107, the gate of the MOS transistor 108, and one end of the first charge holding unit 102. In addition, the pixel circuit 120 is composed of the MOS transistors 105 and 107 to 109 and the first charge holding unit 102. The circuit configuration of the pixel 100 other than the above configuration is the same as that of the reference Figure 2 The circuit configuration of the described pixel 100 is similar, so the description thereof will be omitted.

[0113] Fig.17 The pixel 100 in can perform imaging as follows. First, the MOS transistors 105 and 107 are turned on to reset the photoelectric conversion unit 101. Next, after a predetermined exposure period has passed, the MOS transistor 107 is turned on to reset the first charge holding unit 102. After the reset of the first charge holding unit 102 is completed, the MOS transistor 105 is turned on to transfer the charge generated by the photoelectric conversion unit 101 to the first charge holding unit 102. Thereafter, the MOS transistor 108 generates an image signal based on the charge transferred to and held in the first charge holding unit 102, and the MOS transistor 109 outputs the image signal to the signal line OUT.

[0114] By changing the time of each group of pixels 100 arranged in the row of the pixel array unit 10, the exposure in the photoelectric conversion unit 101 and the output of the image signal after the exposure are performed in sequence, so that an image signal constituting one picture (frame) can be generated. This type of video recording is called a rolling shutter type, and the structure of the pixel 100 can be simplified by applying this video recording method. However, in this rolling shutter type video recording, since the video recording time of each row changes, distortion occurs when a moving subject is recorded. Even in the case of this rolling shutter type imaging element 1, when stray light is incident on the first charge holding unit 102 during the generation of the image signal, noise is generated in the image signal. Therefore, an incident light attenuation unit 170 is arranged to prevent stray light from being incident on the first charge holding unit 102.

[0115] [Pixel structure]

[0116] Fig.18 is a diagram illustrating a configuration example of a pixel according to a fourth embodiment of the present technology. Figure 4 , Fig.18 is a plan view showing the structure of the pixel 100 as viewed from the back side, and is a reference Fig.17 A diagram depicting an example of the arrangement of the photoelectric conversion unit 101 , the first charge holding unit 102 , and the MOS transistors 105 and 107 to 109 .

[0117] The photoelectric conversion unit 101 is arranged on the left side of the pixel 100, and the gate and drain regions of the MOS transistor 105 are sequentially arranged adjacent to the lower right of the photoelectric conversion unit 101. The gate and drain regions of the MOS transistor 107 are sequentially arranged adjacent to the drain region of the MOS transistor 105. Here, the drain region of the MOS transistor 105 corresponds to the source region of the MOS transistor 107, and also constitutes the first charge holding unit 102. The gate and source regions of the MOS transistor 108 and the gate and source regions of the MOS transistor 109 are sequentially arranged adjacent to the drain region of the MOS transistor 107.

[0118] Also in Fig.18 In the pixel 100 in FIG. 1 , a light shielding wall 163 and a light shielding film 161 are arranged around the n-type semiconductor region 141 of the photoelectric conversion unit 101. Furthermore, in a wiring region adjacent to the n-type semiconductor region 141 of the photoelectric conversion unit 101, an incident light attenuating unit 170 composed of a cover portion 171, a wall portion 173, and a bottom portion 174 is arranged.

[0119] The configuration of the image pickup element 1 other than the above-described configuration is similar to that of the image pickup element 1 described in the first embodiment of the present technology, and thus a description thereof will be omitted.

[0120] As described above, in the imaging element that performs rolling shutter imaging, the imaging element 1 according to the fourth embodiment of the present technology can attenuate incident light transmitted through the photoelectric conversion unit 101 by the incident light attenuation unit 170. It is possible to prevent stray light from being incident on the charge holding unit 102 and prevent stray light from being incident on the adjacent pixels 100, and it is possible to reduce the incidence of light transmitted through the photoelectric conversion unit 101 on the charge holding unit and the adjacent pixels, etc.

[0121] <5. Fifth embodiment>

[0122] In the imaging element 1 according to the first embodiment described above, the opening 172 of the cover 171 is arranged at the central portion of the photoelectric conversion unit 101. In contrast, the imaging element 1 according to the fifth embodiment of the present technology is different from the first embodiment described above in that the position of the opening is adjusted.

[0123] [Pixel Circuit Structure]

[0124] Fig.19 is a diagram illustrating a configuration example of a pixel according to a fifth embodiment of the present technology. Figure 3 , Fig.19 is a cross-sectional view showing a configuration example of the pixel 100 . Fig.19 The pixel 100 in the reference Figure 3 The pixel 100 described is different in that the position of the opening portion 172 of the cover portion 171 is changed according to the position of the pixel 100 in the pixel array unit 10 .

[0125] Fig.19 The left pixel 100 and the right pixel 100 in FIG. 1 represent the configurations of the pixels 100 arranged at the left end and the right end of the pixel array unit 10, respectively. Fig.19 As shown in , in the pixel 100 arranged at the left end of the pixel array unit 10, the on-chip lens 154 and the opening 162 of the light shielding film 161 are arranged closer to the right, and the opening 172 of the cover 171 is arranged closer to the left, relative to the photoelectric conversion unit 101. On the other hand, in the pixel 100 arranged at the right end of the pixel array unit 10, the on-chip lens 154 and the opening 162 of the light shielding film 161 are arranged closer to the left, and the opening 172 of the cover 171 is arranged closer to the right, relative to the photoelectric conversion unit 101. It is to be noted that in the pixel 100 arranged at the central portion of the pixel array unit 10, the on-chip lens 154 and the openings 162 and 172 are arranged at the approximately central portion of the photoelectric conversion unit 101. Then, for the pixels 100 arranged toward the end of the pixel array unit 10 , the positions of the on-chip lens 154 and the openings 162 and 172 are adjusted by increasing the amount of change of the opening 172 and the like.

[0126] The subject is formed as an image on the imaging element 1 by a lens arranged on the outside. At this time, the light from the subject is obliquely incident on the pixel 100 arranged at the end of the pixel array unit 10. Therefore, the position of the on-chip lens 154 and the like is adjusted to focus the incident light on the central part of the photoelectric conversion unit 101. This process of adjusting the position of the on-chip lens 154 and the like is called pupil correction. At this time, since such light passing through the photoelectric conversion unit 101 is also obliquely incident, the position of the opening 172 is offset according to the incident angle, thereby adjusting the position of the opening 172 of the cover 171. With this configuration, in the imaging element that performs pupil correction, it is possible to guide the light passing through the photoelectric conversion unit 101 to the incident light attenuation unit 170.

[0127] The configuration of the image pickup element 1 other than the above-described configuration is similar to that of the image pickup element 1 described in the first embodiment of the present technology, and thus a description thereof will be omitted.

[0128] As described above, in the image pickup element 1 that performs pupil correction, the image pickup element 1 according to the fifth embodiment of the present technology can attenuate incident light transmitted through the photoelectric conversion unit 101 by the incident light attenuation unit 170. Stray light can be prevented from being incident on the charge holding unit, and noise in the image signal can be reduced.

[0129] <6. Camera application examples>

[0130] The present technology can be applied to various products. For example, the present technology can be implemented as an imaging element provided in an imaging device such as a camera.

[0131] Fig. 20 : is a block diagram illustrating a schematic configuration example of a camera as an example of an image pickup device to which the present technology can be applied. Fig. 20 The camera 1000 in the embodiment includes a lens 1001, an imaging element 1002, an imaging control unit 1003, a lens driving unit 1004, an image processing unit 1005, an operation input unit 1006, a frame memory 1007, a display unit 1008, and a recording unit 1009.

[0132] A lens 1001 is an imaging lens of the camera 1000. This lens 1001 collects light from a subject and makes the collected light incident on an imaging element 1002 described later to form an image of the subject.

[0133] The imaging element 1002 is a semiconductor element for imaging light from a subject collected by the lens 1001. The imaging element 1002 generates an analog image signal based on the irradiated light, converts the generated analog image signal into a digital image signal, and outputs the converted digital image signal.

[0134] The imaging control unit 1003 controls imaging in the imaging element 1002. The imaging control unit 1003 controls the imaging element 1002 by generating a control signal and outputting the generated control signal to the imaging element 1002. In addition, the imaging control unit 1003 can perform autofocus in the camera 1000 based on the image signal output from the imaging element 1002. Here, the autofocus is a system for detecting the focal position of the lens 1001 and automatically adjusting the measured focal position. As this autofocus, a technique for detecting the focal position by detecting the image plane phase difference by the phase difference pixels arranged in the imaging element 1002 (image plane phase difference autofocus) can be used. In addition, a technique for detecting the position with the highest contrast of the image as the focal position (contrast autofocus) can also be applied. The imaging control unit 1003 adjusts the position of the lens 1001 via the lens driving unit 1004 based on the measured focal position and performs autofocus. It should be noted that the imaging control unit 1003 can be composed of, for example, a digital signal processor (DSP: Digital Signal Processor) equipped with firmware.

[0135] The lens driving unit 1004 drives the lens 1001 based on the control of the imaging control unit 1003. The lens driving unit 1004 changes the position of the lens 1001 by using a built-in motor, thereby making it possible to drive the lens 1001.

[0136] The image processing unit 1005 processes the image signal generated by the image pickup element 1002. This processing corresponds to, for example, demosaicing for generating an image signal of a missing color among image signals corresponding to red, green, and blue of each pixel, noise reduction for eliminating noise of the image signal, encoding of the image signal, etc. The image processing unit 1005 can be configured by, for example, a microcomputer equipped with firmware.

[0137] The operation input unit 1006 receives an operation input from a user of the camera 1000. For example, a button or a touch panel can be used for the operation input unit 1006. The operation input received by the operation input unit 1006 is transmitted to the imaging control unit 1003 and the image processing unit 1005. Thereafter, a process corresponding to the operation input, for example, a process such as imaging of a subject, is started.

[0138] The frame memory 1007 is a memory for storing frames including image signals constituting one screen. The frame memory 1007 is controlled by the image processing unit 1005, and the frame memory 1007 holds the frames during the image processing.

[0139] The display unit 1008 displays the image processed by the image processing unit 1005. For example, a liquid crystal panel can be used for the display unit 1008.

[0140] The recording unit 1009 records the image processed by the image processing unit 1005. For example, a memory card or a hard disk can be used for the recording unit 1009.

[0141] The camera to which the present invention can be applied has been described so far. The present technology can be applied to the imaging element 1002 in the above-described configuration. Specifically, the camera can be applied to the imaging element 1002 in the above-described configuration. Figure 1 The described imaging element 1 is applied to the imaging element 1002. By applying the imaging element 1 to the imaging element 1002, an image signal with less noise can be obtained. Note that the image processing unit 1005 is an example of a processing circuit described in the claims. The camera 1000 is an example of an imaging device described in the claims.

[0142] Furthermore, although the description is made here by taking a camera as an example, the technology according to the present invention can be applied to other imaging devices such as a surveillance device, for example.

[0143] Finally, the description of each embodiment above is an example of the present technology, and the present technology is not limited to the above embodiments. Therefore, it goes without saying that various changes other than the above embodiments can be made according to the design, etc., as long as these changes do not deviate from the technical idea of ​​the present technology.

[0144] It should be noted that the present technology can also be configured as described below.

[0145] (1) An imaging device comprising:

[0146] a pixel including a photoelectric conversion unit formed in a semiconductor substrate and performing photoelectric conversion based on incident light, and a pixel circuit generating an image signal according to charges generated by the photoelectric conversion;

[0147] a wiring layer which is arranged on a surface of the semiconductor substrate different from a surface on which the incident light is incident and transmits the image signal or a signal applied to the pixel circuit; and

[0148] An incident light attenuation unit is configured to attenuate the incident light transmitted through the photoelectric conversion unit.

[0149] (2) The imaging element according to (1) above, wherein the incident light attenuating unit includes: a cover having an opening that is arranged between the semiconductor substrate and the wiring layer and allows light transmitted through the photoelectric conversion unit to be incident; and a wall that surrounds the opening.

[0150] (3) The image pickup element according to (2) above, wherein the incident light attenuating unit includes the wall portion formed simultaneously with the wiring layer.

[0151] (4) The image pickup element according to (2) above, wherein the incident light attenuating unit further includes a bottom portion that is adjacent to the wall portion and is arranged to face the cover portion.

[0152] (5) The image pickup element according to (4) above, wherein the incident light attenuating unit includes the bottom portion formed simultaneously with the wiring layer.

[0153] (6) The image pickup element according to any one of (2) to (5) above, wherein the opening portion is arranged in the incident light attenuating unit at a position shifted according to an incident angle of the incident light.

[0154] (7) An imaging element according to any one of (1) to (6) above, wherein the pixel circuit includes: a charge holding unit that holds the generated charge; and an image signal generating unit that generates an image signal based on the held charge.

[0155] (8) The image pickup element according to (7) above, further comprising a light shielding wall which is arranged between the photoelectric conversion unit and the charge holding unit and shields the incident light.

[0156] (9) The imaging element according to (7) or (8) above, further comprising a shielding film which is arranged near the charge holding unit of the surface of the semiconductor substrate on which the incident light is incident and shields the incident light.

[0157] (10) A camera device comprising:

[0158] a pixel including a photoelectric conversion unit formed in a semiconductor substrate and performing photoelectric conversion based on incident light, and a pixel circuit generating an image signal according to charges generated by the photoelectric conversion;

[0159] a wiring layer which is arranged on a surface of the semiconductor substrate different from a surface on which the incident light is incident and transmits the image signal or a signal applied to the pixel circuit;

[0160] an incident light attenuation unit, the incident light attenuation unit attenuating the incident light passing through the photoelectric conversion unit; and

[0161] A processing circuit is used to process the transmitted image signal.

[0162] Reference numerals list

[0163] 1. 1002 Camera Component

[0164] 10 pixel array unit

[0165] 20 vertical drive units

[0166] 30 columns of signal processing units

[0167] 40 Control Unit

[0168] 100 pixels

[0169] 101 Photoelectric conversion unit

[0170] 102 first charge retention unit

[0171] 103 Second charge retention unit

[0172] 105 to 109 MOS transistors

[0173] 110 Image signal generating unit

[0174] 120 pixel circuit

[0175] 130 Insulation layer

[0176] 131 Wiring layer

[0177] 132 Contact plug

[0178] 133 Via Plug

[0179] 140 Semiconductor substrate

[0180] 151 Separation Area

[0181] 152 Insulation film

[0182] 153 Color Filters

[0183] 154 On-chip lens

[0184] 161 shading film

[0185] 162, 164, 172, 175 opening

[0186] 163 Blackout wall

[0187] 171 cover

[0188] 173 Wall

[0189] 174 bottom

[0190] 176 Anti-reflective film

[0191] 1000 Camera

[0192] 1005 Image Processing Unit

Claims

1. An imaging element, include: a pixel including a photoelectric conversion unit formed in a semiconductor substrate and performing photoelectric conversion based on incident light, and a pixel circuit generating an image signal according to charges generated by the photoelectric conversion; a wiring layer which is arranged on a surface of the semiconductor substrate different from a surface on which the incident light is incident and transmits the image signal or a signal applied to the pixel circuit; as well as an incident light attenuation unit, the incident light attenuation unit attenuating the incident light passing through the photoelectric conversion unit, The incident light attenuation unit includes: a cover having an opening, the opening being arranged between the semiconductor substrate and the wiring layer and allowing light transmitted through the photoelectric conversion unit to be incident; and a wall surrounding the opening. The cover portion covers the entire area of ​​the pixel.

2. The imaging element according to claim 1, in, The incident light attenuating unit includes the wall portion formed simultaneously with the wiring layer.

3. The imaging element according to claim 1, in, The incident light attenuation unit further includes a bottom portion adjacent to the wall portion and arranged to face the cover portion.

4. The imaging element according to claim 3, in, The incident light attenuating unit includes the bottom portion formed simultaneously with the wiring layer.

5. The imaging element according to claim 1, in, The opening portion is arranged in the incident light attenuating unit at a position shifted according to an incident angle of the incident light.

6. The imaging element according to any one of claims 1 to 5, in, The pixel circuit includes: a charge holding unit that holds the generated charge; and an image signal generating unit that generates the image signal based on the held charge. 7 . The image pickup element according to claim 6 , further comprising a light shielding wall which is arranged between the photoelectric conversion unit and the charge holding unit and which shields the incident light. 8 . The image pickup element according to claim 6 , further comprising a shielding film which is arranged near the charge holding unit of the surface of the semiconductor substrate on which the incident light is incident and which shields the incident light.

9. A camera device, include: The imaging element according to any one of claims 1 to 8; as well as A processing circuit is used to process the transmitted image signal.

Images