Imaging element and imaging device

Abstract

An imaging element is provided, comprising: a first layer having a photoelectric conversion unit that performs photoelectric conversion on light to generate charge; a second layer, which is stacked with the first layer and has a first circuit for processing a signal based on the charge generated by the photoelectric conversion unit; and a third layer, which is stacked with the second layer and has a second circuit for processing the signal processed by the first circuit, an insulating layer disposed between the third and the second layer, and a thermally conductive layer disposed in the insulating layer and having a higher thermal conductivity than the insulating layer.

Description

Technical Field

[0001] This invention relates to imaging elements and imaging devices. Background Technology

[0002] In imaging elements, a structure is known that is formed by stacking a layer having a plurality of pixels including a photoelectric conversion unit and a layer having a signal processing circuit (for example, see Patent Document 1).

[0003] Patent Document 1: Japanese Patent Application Publication No. 2015-128187

[0004] In the aforementioned imaging element, heat is generated in the signal processing circuit in order to process the signal output from the pixel. Summary of the Invention

[0005] In a first aspect of the present invention, an imaging element is provided, comprising: a first layer having a photoelectric conversion unit that performs photoelectric conversion on light to generate charge; a second layer stacked with the first layer and having a first circuit for processing a signal based on the charge generated by the photoelectric conversion unit; and a third layer stacked with the second layer and having a second circuit for processing the signal processed by the first circuit, an insulating layer disposed between the third and the second layer, and a heat-conducting layer disposed in the insulating layer and having a higher thermal conductivity than the insulating layer.

[0006] In a second aspect of the present invention, a shooting device having a shooting element of the first aspect is provided.

[0007] Furthermore, the above summary of the invention does not enumerate all the essential features of the invention. Additionally, sub-combinations of these feature groups can also constitute inventions. Attached Figure Description

[0008] Figure 1 This is a diagram showing an outline of the imaging element 10 in this embodiment.

[0009] Figure 2 This is a diagram showing an example of a cross-section of the imaging element 10 in the XZ direction according to this embodiment.

[0010] Figure 3 This is a diagram showing an example of a cross-section of the imaging element 10 in the XZ direction according to this embodiment.

[0011] Figure 4 This is a diagram showing an example of a cross-section of the imaging element 10 in the XZ direction according to this embodiment.

[0012] Figure 5 This is a diagram showing an example of a cross-section of the imaging element 10 in the XY direction according to this embodiment.

[0013] Figure 6 This is a diagram showing an example of a cross-section of the imaging element 10 in the XY direction according to this embodiment.

[0014] Figure 7 This is a diagram showing an example of a cross-section of the imaging element 10 in the XZ direction according to this embodiment.

[0015] Figure 8 This is a diagram showing an example of a cross-section of the imaging element 10 in the XY direction according to this embodiment.

[0016] Figure 9 This is a diagram showing an example of a cross-section of the imaging element 10 in the XY direction according to this embodiment.

[0017] Figure 10 This is a diagram showing an example of a cross-section of the imaging element 10 in the XY direction according to this embodiment.

[0018] Figure 11 This is a diagram showing an example of a cross-section of the imaging element 10 in the XY direction according to this embodiment.

[0019] Figure 12 This is a diagram showing an example of a cross-section of the imaging element 10 in the XZ direction according to this embodiment.

[0020] Figure 13 This is a diagram showing an example of a cross-section of the imaging element 10 in the XZ direction according to this embodiment.

[0021] Figure 14 This is a diagram showing an example of a cross-section of the imaging element 10 in the XZ direction according to this embodiment.

[0022] Figure 15 This is a diagram showing an example of a cross-section of the imaging element 10 in the XZ direction according to this embodiment.

[0023] Figure 16 This is a block diagram illustrating an example of the configuration of the imaging device 500 in this embodiment. Detailed Implementation

[0024] The present invention will now be described through embodiments thereof, but these embodiments are not intended to limit the scope of the invention as claimed. Furthermore, not all combinations of features described in the embodiments are necessarily necessary for the solution of the invention.

[0025] Figure 1 This diagram illustrates a schematic of the imaging element 10 according to this embodiment. The imaging element 10 generates image data based on light incident from the subject. The imaging element 10 is a stacked structure consisting of a first layer 100, a second layer 200, and a third layer 300. Furthermore, Figure 1This diagram illustrates the positional relationships of the layers in the imaging element 10 and the general outline of the processing in each layer. For components present in each layer, such as wiring layers that connect the layers, and wiring within those wiring layers, please refer to... Figure 2 The cross-sectional view of the imaging element 10 shown will be explained, etc. Figure 1 The Chinese text is omitted for brevity.

[0026] The first layer 100 has pixels that output signals generated based on incident light. Multiple pixels are disposed in the first layer 100 and arranged along a row and column direction. Each pixel has a photoelectric conversion unit 102, a transmission unit, a floating diffusion region (FD), a reset unit, and an output unit, described later. Alternatively, a pixel may have a structure in which multiple photoelectric conversion units share the FD, reset unit, and output unit.

[0027] The photoelectric conversion unit 102 converts incident light into electrical charge through photoelectric conversion. The photoelectric conversion unit 102 is, for example, a photoelectric conversion element such as a photodiode. A plurality of photoelectric conversion units 102 are provided on the first substrate 110 and arranged along the row and column direction.

[0028] The transmission section, composed of a transmission transistor, transmits the charge obtained by photoelectric conversion by the photoelectric conversion section 102 to the FD. The FD stores (holds) the charge transmitted to the FD and converts it into a voltage obtained by dividing by the capacitance value. The FD is an accumulation section that stores the charge generated by the photoelectric conversion section 102. The output section has an amplification section and a selection section.

[0029] The amplification section consists of an amplifying transistor whose gate (terminal) is connected to the FD (discharge generator), and outputs a signal based on the charge accumulated in the FD. The drain (terminal) of the amplifying transistor is supplied with a power supply voltage. The source (terminal) of the amplifying transistor is connected to a signal line via a selection section. The amplifying transistor functions as part of a source follower circuit. The amplification section and the selection section constitute the output section, which generates and outputs a signal based on the charge generated by the photoelectric conversion section 102.

[0030] The reset section, composed of a reset transistor, electrically connects or disconnects the FD and the power supply voltage. The reset section resets the charge accumulated in the FD. The reset section also discharges the charge accumulated in the FD, thus resetting the voltage of the FD.

[0031] The selection section is composed of a selection transistor, which electrically connects or disconnects the amplification section and the signal line. When the selection transistor is in the on state, it outputs a signal from the amplification section to the signal line. In addition, the transmission transistor, amplification transistor, selection transistor, and reset transistor are included in transistor 105 described later.

[0032] The second layer 200 includes a signal processing unit that processes signals output from pixels disposed on the first layer 100; and a control unit for controlling pixels. The second layer 200 includes a plurality of signal processing circuits 202 disposed on the second substrate 210 as signal processing units. The signal processing circuits 202 are an example of the first circuit. Additionally, the second layer 200 includes a plurality of control circuits disposed on the second substrate 210 as control units. The signal processing circuits 202 and control circuits are provided for each photoelectric conversion unit 102. Furthermore, the signal processing circuits 202 and control circuits may also be provided for each plurality of photoelectric conversion units 102.

[0033] In this example, the signal processing circuit 202 includes an AD converter, etc. The AD converter in each signal processing circuit 202 converts the analog signal output from the pixel into a digital signal. The signal processing circuit 202 outputs the converted digital signal. The control circuit controls the start and end of light reception in the photoelectric conversion unit 102 by controlling the pixel (transmission unit, reset unit, selection unit).

[0034] The third layer 300 has an image processing unit that processes signals output from the signal processing circuit provided in the second layer 200. The third layer 300 also has an image processing circuit 302 provided on the third substrate 310 as the image processing unit. The image processing circuit 302 is an example of a second circuit. In this example, the image processing circuit 302 is provided for each of the plurality of signal processing circuits 202 and control circuits, and is connected to each signal processing circuit 202 and control circuit via a bus. The image processing circuit 302 processes the signals output from the signal processing circuits 202 to generate signals for controlling pixels (transmission unit, reset unit, selection unit), image data, etc. The signals for controlling pixels generated by the image processing circuit 302 are transmitted to the control circuit of the second layer 200. The image data, etc., generated by the image processing circuit 302 are transmitted to the first layer 100, and output from the first layer 100 or the third layer 300 to the outside of the imaging element 10. Alternatively, the image processing circuit 302 may be provided for each signal processing circuit 202 and control circuit.

[0035] Figure 2 This diagram shows an example of a cross-section in the XZ direction of the imaging element 10 according to this embodiment. In this example, a back-illuminated imaging element 10 is shown, but the imaging element 10 is not limited to the back-illuminated type. The imaging element 10 in this example includes a first layer 100, a second layer 200, and a third layer 300. Furthermore, as shown in the diagram, light from the subject is incident in the direction indicated by the hollow arrow (the negative Z-axis direction in the diagram). In this embodiment, the side of the first layer 100 from which light is incident (the positive Z-axis side in the diagram) is sometimes referred to as the surface, and the side opposite to that surface (the negative Z-axis side in the diagram) is referred to as the back surface.

[0036] The X-axis and Y-axis are orthogonal to each other, and the Z-axis is orthogonal to the XY plane. Furthermore, the direction parallel to the Z-axis is sometimes referred to as the stacking direction of the imaging element 10. The terms "up" and "down" are not limited to the vertical direction of gravity. These terms refer to relative directions with respect to the Z-axis.

[0037] One example of the first layer 100 is a back-illuminated CMOS image sensor. The first layer 100 has a first substrate 110 and a first wiring layer 120. The first substrate 110 is located on the positive side of the Z-axis compared to the first wiring layer 120. The first substrate 110 has a plurality of photoelectric conversion units 102 arranged in two dimensions and accumulating charge based on incident light, and a plurality of transistors 105.

[0038] Multiple color filters 104 are provided at a position on the positive Z-axis side of the first substrate 110, separated by a passivation film 103. The color filters 104 are optical filters that allow light of a specific wavelength to pass through. The multiple color filters 104 allow light of different wavelengths to pass through in a specific array (e.g., a Bayer array).

[0039] A microlens 101 is provided at a position closer to the positive Z-axis than the color filter 104. The microlens 101 is provided for each photoelectric conversion unit 102, so that the incident light is focused on the photoelectric conversion unit 102.

[0040] The first wiring layer 120 is located closer to the second layer 200 than the first substrate 110 (on the negative Z-axis side in the figure). The first wiring layer 120 has multiple wirings 180 made of a conductive film (metal film), multiple connection portions 190, and an insulating film (insulating layer). The first wiring layer 120 has multiple wirings 180 that are electrically connected to a power source or circuit, that transmit signals from the first layer 100 (pixel) to the second layer 200, and that transmit signals from the second layer 200 to the first layer 100 (pixel). The first wiring layer 120 can also be multilayered, and may also include passive and active components. The connection portions 190 are provided on the surface of the first wiring layer 120 (the surface on the negative Z-axis side) and are connected to the wirings 180. Furthermore, as described later, the connection portions 190 are also used to assist in the connection between layers. The connection portions 190 are, for example, bumps, pads, electrodes, etc., and are formed of a conductive material such as copper. In addition, the connectors can also be made of gold, silver, or aluminum. An insulating layer (insulating film) is formed between the multiple wirings 180 and the multiple connectors 190.

[0041] The second layer 200 includes a second substrate 210, a second wiring layer 220, and a wiring layer 230, which are equipped with signal processing circuitry 202 and control circuitry. The second wiring layer 220 is located closer to the first layer 100 (positive Z-axis side in the figure) than the second substrate 210. The wiring layer 230 is located closer to the third layer 300 (negative Z-axis side in the figure) than the second substrate 210, and is located between the second substrate 210 and the third layer 300.

[0042] The second layer 200, like the first layer 100, includes: a plurality of wirings 180 disposed on the second wiring layer 220; a plurality of connecting portions 190 disposed on the second wiring layer 220 and wiring layer 230; and an insulating film (insulating layer) disposed on the second wiring layer 220 and wiring layer 230. The second wiring layer 220 has a plurality of wirings 180 and connecting portions 190, which are used for electrical connection to a power supply or circuit, for transmitting signals from the first layer 100 (pixel) to the signal processing circuit 202, and for transmitting signals from the control circuit to the first layer 100 (pixel). The wirings 180 and connecting portions 190 may also be disposed on the wiring layer 230.

[0043] The second layer 200 also has a TSV (through-silicon spool) 106 that connects the circuits respectively disposed on the back side of the table to each other. The TSV 106 is preferably disposed in the peripheral area. The TSV 106 transmits image data generated by the image processing circuit 302 to the first layer 100. Alternatively, the TSV 106 may also be disposed in the first layer 100 and the third layer 300.

[0044] Furthermore, as described above, the signal processing circuit 202 and the control circuit are configured for each pixel having the photoelectric conversion unit 102, or for each block composed of multiple pixels. Signal lines in the plurality of wirings 180 that transmit signals from the pixels to the AD conversion unit of the signal processing circuit 202, and control lines that transmit signals from the control circuit to the pixels, are provided between the photoelectric conversion unit 102 and the signal processing circuit 202 and the control circuit. Thus, the signal processing circuit 202 can read signals pixel by pixel or pixel block by pixel, and the control circuit can control pixels pixel by pixel or pixel block by pixel.

[0045] The third layer 300 has a third substrate 310 with an image processing circuit 302 and a third wiring layer 320. The third wiring layer 320 is disposed between the third substrate 310 and the second layer 200.

[0046] Like the first layer 100, the third layer 300 has wiring 180 and multiple connection portions 190 disposed on the third wiring layer 320, as well as an insulating film (insulating layer). The third wiring layer 320 has multiple wiring 180 and connection portions 190, which are used for electrical connection with power supply or circuit, for transmitting signals from signal processing circuit 202 to image processing circuit 302, and for transmitting signals from image processing circuit 302 to control circuit of second layer 200.

[0047] Furthermore, the first layer 100, the second layer 200, and the third layer 300 are stacked together by electrical connection between each other through the connection portion 190 provided in each layer and by bonding of the wiring layer (insulation layer) of each layer to each other.

[0048] If layer 100 and layer 200 are stacked, then layer 150 is formed by the negative Z-axis surface of layer 120 and the positive Z-axis surface of layer 220. Similarly, if layer 200 and layer 300 are stacked, then layer 160 is formed by the negative Z-axis surface of layer 230 and the positive Z-axis surface of layer 320. Multiple connecting portions 190 are arranged on layer 150 and layer 160. Specifically, corresponding connecting portions 190 are aligned with each other, and the two layers are stacked, thereby electrically connecting the aligned connecting portions.

[0049] Layer 100, Layer 200, and Layer 300 are formed by stacking the wafers in their pre-chipping state and then cutting the stacked wafers (monolithization).

[0050] During wafer stacking, an activation device is used to activate the surfaces of the wafers to be stacked by scanning plasma. After activation, the wafers are bonded together using hydrogen bonds, van der Waals bonds, and covalent bonds generated through contact, forming a laminated substrate. If hydrogen bonds are generated between the wafers due to their contact, after the laminated substrate is formed, it is heated using a heating device such as an annealing furnace to generate covalent bonds between the wafers.

[0051] Furthermore, wafer activation refers to the process of treating at least one of the laminated surfaces to achieve a solid-state bond where the laminated surfaces of the wafers are bonded together by forming hydrogen bonds, van der Waals bonds, covalent bonds, etc., through contact without melting. For example, activation includes promoting bonding by creating dangling bonds on the laminated surfaces of the wafers.

[0052] More specifically, the activation device irradiates oxygen, which is the process gas, into plasma under a reduced pressure atmosphere, for example, by stimulating oxygen ions onto the surfaces to be laminated. For example, in the case where the wafer is a silicon substrate with an oxide film such as SiO, the SiO bonds in the laminated surfaces are broken by the irradiation with oxygen ions, forming dangling bonds between Si and O.

[0053] When the laminated surfaces with dangling bonds are exposed to, for example, the atmosphere, moisture in the air combines with the dangling bonds, and the substrate surface becomes hydrophilic, covered with hydroxyl groups (OH groups), making it easy to combine with water molecules. In other words, activation promotes the hydrophilicity of the laminated surfaces. In addition, in solid-phase bonding, the presence of impurities such as oxides and defects in the laminated surfaces can affect the bonding strength, so activation may also include cleaning the laminated surfaces.

[0054] Furthermore, wafer activation can also include hydrophilization of the laminated surfaces by applying pure water to the surfaces to be laminated using a hydrophilization device. Through hydrophilization, the laminated surfaces of the wafer become a state with attached OH groups, that is, a state with OH group-terminated.

[0055] By heating the laminated substrate, the interconnects located on the laminated surfaces of the wafer are integrated and electrically connected. When the interconnects are made of a conductive material such as copper, the aligned interconnects expand due to the heating process and are pressed together, thus being bonded by solid-phase diffusion.

[0056] Conventionally, pixels with photoelectric conversion units, AD conversion units, and control units are disposed on the same substrate. The AD conversion units and control units are located in the area surrounding the region containing multiple pixels. The imaging element 10 of this embodiment has a stacked structure, with pixels having photoelectric conversion units 102 disposed on the first layer 100, and signal processing circuit 202 and control circuit having AD conversion units disposed on the second layer 200. The signal processing circuit 202 reads signals based on pixels having photoelectric conversion units 102 or based on blocks composed of multiple pixels. The control circuit controls pixels based on pixels having photoelectric conversion units 102 or based on blocks composed of multiple pixels. Therefore, the imaging element 10 achieves higher-speed signal processing than conventional imaging elements. On the other hand, the imaging element 10 has more signal processing circuits 202 and control circuits than conventional imaging elements; therefore, the heat generated by the signal processing circuits 202 and control circuits is increased compared to conventional imaging elements. In particular, the heat generated by the signal processing circuit 202 is increased compared to conventional imaging elements.

[0057] Furthermore, conventionally, the image processing unit that performs image processing on the signal output from the imaging element is located outside the imaging element. In this embodiment, the imaging element 10 has a third layer 300 with an image processing circuit 302 as the image processing unit. The image processing circuit 302 processes signals according to the signal processing circuit 202 or according to blocks composed of multiple signal processing circuits 202. Therefore, the imaging element 10 achieves image processing at a higher speed than conventional imaging elements. On the other hand, because the imaging element 10 has an image processing circuit 302, the heat generation is further increased compared to conventional imaging elements.

[0058] Therefore, the heat generated in the signal processing circuit 202 and the image processing circuit 302 is transferred to the first layer 100. If heat is transferred to the first layer and the temperature of the pixels (photoelectric conversion unit 102, FD, transmission unit, output unit) rises, noise such as dark current and shot noise is easily generated. As a result, the noise contained in the signal generated by the pixels increases. This increased noise becomes a cause of image quality degradation.

[0059] Therefore, in the imaging element 10, it is necessary to release the heat generated in the signal processing circuit 202 and the image processing circuit 302 to the outside. In particular, it is necessary to release the heat generated in the signal processing circuit 202 and the image processing circuit 302 to a position further away from the first layer on the negative Z-axis, so that the heat is not transferred to the pixels. Alternatively, it is necessary to provide heat insulation at a position further away from the pixels on the negative Z-axis, so that the heat is not transferred to the pixels.

[0060] In this example, a thermally conductive layer is disposed on the third wiring layer 320. The thermally conductive layer has a higher thermal conductivity than the insulating layer of the third wiring layer 320. The thermally conductive layer is formed of, for example, copper. Alternatively, the thermally conductive layer may also be formed of gold, silver, or aluminum.

[0061] like Figure 2 As shown, the thermally conductive layer in this example can be a thermally conductive layer 410 formed in the same process as wiring 180. However, although wiring 180 is electrically connected to a power source or circuit, the thermally conductive layer 410 is not electrically connected to a power source or circuit. Figure 2 In the middle, the thermal conductive layer 410 is shown as a multi-layered layer, but it can also be a single layer.

[0062] In this example, the heat generated in the image processing circuit 302 provided on the third substrate 310 is transferred to the thermally conductive layer 410 provided on the third wiring layer 320. The heat transferred to the thermally conductive layer 410 is released to the outside via the thermally conductive layer 410. That is, the thermally conductive layer 410 promotes the dissipation of heat generated in the image processing circuit 302. In this way, the transfer of heat generated in the image processing circuit 302 to the first layer 100 can be suppressed.

[0063] In addition, Figure 2In this circuit, the thermally conductive layer 410 is disposed on the third layer 300, but it can also be disposed on the second layer 200. Alternatively, it can be disposed on both the second layer 200 and the third layer 300. Specifically, the thermally conductive layer 410, which has a higher thermal conductivity than the wiring layer 230, is disposed on the wiring layer 230. As a result, the heat generated in the signal processing circuit 202 disposed on the second substrate 210 is transferred to the thermally conductive layer 410 disposed on the wiring layer 230. The heat transferred to the thermally conductive layer 410 is released to the outside via the thermally conductive layer 410. The thermally conductive layer 410 promotes the dissipation of heat generated in the signal processing circuit 202. In addition, the thermally conductive layer 410 is disposed at a position closer to the third layer 300 (negative Z-axis side) than the second substrate 210, thus suppressing the transfer of heat generated in the signal processing circuit 202 to the first layer 100.

[0064] Figure 3 This is a diagram showing an example of a cross-section in the XZ direction of the imaging element 10 according to this embodiment. Wherein, for... Figure 2 Common elements are labeled with the same reference numerals, and descriptions are omitted.

[0065] The thermally conductive layer in this example has: a first thermally conductive layer 412 disposed in the third wiring layer 320; and a second thermally conductive layer 414 disposed in the third wiring layer 320 on the side of the second layer 200 (positive Z-axis side) closer than the first thermally conductive layer 412, and thicker than the first thermally conductive layer 412. The first thermally conductive layer 412 and the second thermally conductive layer 414 are... Figure 2 An example of the heat-conducting layer 410 is shown. Here, "thickness" refers to the length in the XZ direction.

[0066] The second thermally conductive layer 414, which is thicker than the first thermally conductive layer 412, has a higher thermal conductivity than the first thermally conductive layer 412. Therefore, heat generated not only in the image processing circuit 302 but also in the signal processing circuit 202 of the second layer 200 is transferred to the second thermally conductive layer 414 and released to the outside of the imaging element 10. In other words, the second thermally conductive layer 414 promotes heat dissipation from the signal processing circuit 202. Furthermore, it can suppress the transfer of heat generated in the signal processing circuit 202 to the first layer 100.

[0067] Furthermore, regarding the heat generated in the second layer 200, the heat originating from the signal processing circuit 202 has been described, but heat is also generated in the control circuit of the second layer 200. The second heat-conducting layer 414 can also be used to dissipate the heat generated in the control circuit of the second layer 200. Regarding heat dissipation countermeasures, when referring to the signal processing circuit 202, the control circuit of the second layer 200 is also included.

[0068] Figure 4 This is a diagram showing an example of a cross-section in the XZ direction of the imaging element 10 according to this embodiment. Wherein, for... Figure 2Common elements are labeled with the same reference numerals, and descriptions are omitted.

[0069] In this example, the thermal conductive layer has a thermal plate that covers a light-receiving area having one or more pixels. The light-receiving area refers to the area obtained by projecting the area having one or more pixels onto a surface parallel to the XY plane.

[0070] As an example, the heat-conducting plate includes a first heat-conducting plate 420 disposed on the second layer 200 and a second heat-conducting plate 421 disposed on the third layer 300. The first heat-conducting plate 420 is disposed on the wiring layer 230, and the second heat-conducting plate 421 is disposed on the third wiring layer 320. The first heat-conducting plate 420 and the second heat-conducting plate 421 are formed of thermally conductive materials such as copper and aluminum. Alternatively, the heat-conducting layer may also be formed of metals such as gold or silver. Furthermore, the heat-conducting plate may also include only one of the first heat-conducting plate 420 and the second heat-conducting plate 421.

[0071] The area of ​​the second heat-conducting plate 421 is larger than that of the first heat-conducting plate 420. The second heat-conducting plate 421, being larger than the first heat-conducting plate 420, has a higher thermal conductivity than the first heat-conducting plate 420, and therefore transfers more heat than the first heat-conducting plate 420. Therefore, the heat generated in the signal processing circuit 202 is transferred to the first heat-conducting plate 420 and also to the second heat-conducting plate 421. The heat transferred to the first heat-conducting plate 420 is released to the outside of the imaging element 10 via the second heat-conducting plate 421. Additionally, the heat generated in the image processing circuit 302 is transferred to the second heat-conducting plate 421 and released to the outside of the imaging element 10. In other words, the first heat-conducting plate 420 and the second heat-conducting plate 421 facilitate the dissipation of heat generated in the signal processing circuit 202 and the image processing circuit 302.

[0072] The first heat-conducting plate 420 and the second heat-conducting plate 421 can also be connected by a connecting portion 422. The connecting portion 422 is formed of a thermally conductive material extending in the stacking direction. As a result, the heat transferred to the first heat-conducting plate 420 can be easily transferred to the second heat-conducting plate 421 and released to the outside of the imaging element 10.

[0073] The entire circumference of the first heat-conducting plate 420 and the second heat-conducting plate 421 can be covered by an insulating layer. "Entire circumference covered by an insulating layer" means that the upper surface, lower surface, and sides are all covered by the insulating layer. For example, the insulating layer is the same as that found in the wiring layer 230 and the third wiring layer 320. Thus, the first heat-conducting plate 420 and the second heat-conducting plate 421 are electrically isolated from other elements.

[0074] Figure 5 This is a diagram showing an example of a cross-section of the imaging element 10 in the XY direction according to this embodiment. Specifically, Figure 5This indicates the state of the third layer 300 as viewed from the stack-up surface 160 toward the negative Z-axis. For simplicity, elements such as the third wiring layer 320 have been omitted.

[0075] As shown in (a), the laminated surface 160 in this example has: a first region 162, which includes the vicinity of the center of the laminated surface 160; and a second region 164, which is located between the outer periphery of the first region 162 and the outer periphery of the laminated surface 160. The first region 162 refers to the region where the element for joining (laminating) the second layer 200 and the third layer 300 is not disposed on the laminated surface 160, and the second region 164 refers to the region where the element is disposed on the laminated surface 160. In the second region 164, the connection portion 190 for electrically connecting the circuit provided in the second layer 200 and the circuit provided in the third layer 300 is disposed on the laminated surface 160 as an element for joining (laminating) the second layer 200 and the third layer 300.

[0076] An enlarged view of the area near the boundary between the first region 162 and the second region 164 is shown in (b). In this example, in the wiring layer 230, the connector 190 is disposed on the lamination surface 160 in the second region 164. Additionally, in the third wiring layer 320, the second heat-conducting plate 421 is provided to cover the first region 162, and the connector 190 is disposed on the lamination surface 160 in the second region 164. The second heat-conducting plate 421 is an example of a heat-conducting layer. In this example, the second region 164 has a plurality of third regions 166 with two connectors 190 disposed diagonally. Furthermore, as long as bonding strength and flatness are ensured, the number of connectors 190 disposed in the third regions 166 can be one, or more than two. Furthermore, the shape of the XY direction cross-section of the connector 190 is represented by a rectangle, but it is not limited to this and can be other shapes.

[0077] Generally, the heat generated in a circuit is greater near the center than in the surrounding area. In the imaging element 10 of this embodiment, the heat generated near the center of the second substrate 210 where the signal processing circuit 202 is located, or near the center of the third substrate 310 where the image processing circuit 302 is located, is greater than the heat generated in the surrounding areas of each circuit. Therefore, by uniformly arranging the multiple connecting portions 190 on the outer periphery of the laminated surface 160 to ensure bonding strength, and by arranging the second heat-conducting plate 421 near the center where the heat generation is greater, the heat generated in the circuit can be effectively dissipated to the outside.

[0078] Figure 6 This is a diagram showing an example of a cross-section in the XY direction of the imaging element 10 according to this embodiment. Wherein, for... Figure 5 Common elements are labeled with the same reference numerals, and descriptions are omitted.

[0079] As shown in (b), in this example, with Figure 5 Similarly, in wiring layer 230, the connector 190 is disposed on the lamination surface 160 in the second region 164. Furthermore, in the third wiring layer 320, the second heat-conducting plate 421 is provided to cover the first region 162, and the connector 190 is disposed on the lamination surface 160 in the second region 164. In this example, in wiring layer 230, the first heat-conducting plate 420 is provided to cover the first region 162. Additionally, the connecting portion 422 is provided along the outer periphery of the second heat-conducting plate 421. The connecting portion 422 connects the first heat-conducting plate 420 (not shown) and the second heat-conducting plate 421. Thus, the heat transferred to the first heat-conducting plate 420 is further transferred to the second heat-conducting plate 421 and released to the outside of the imaging element 10.

[0080] Figure 7 This is a diagram showing an example of a cross-section in the XZ direction of the imaging element 10 according to this embodiment. Wherein, for... Figure 2 Common elements are labeled with the same reference numerals, and descriptions are omitted.

[0081] In this example, the plurality of connecting portions disposed on the laminated surface 160 include: connecting portions 190, which are opposite to and connected to each other in the lamination direction; and non-connecting portions 430, which are not opposite to other connecting portions in the lamination direction. The non-connecting portion 430 is an example of a heat-conducting layer. The non-connecting portion 430 can be formed in the same process as the connecting portion 190. However, although the connecting portion 190 electrically connects the circuit provided in the second layer 200 to the circuit provided in the third layer 300, the non-connecting portion 430 is not connected to other connecting portions and does not electrically connect the circuit provided in the second layer 200 to the circuit provided in the third layer 300. In other words, the non-connecting portion is a dummy connecting portion.

[0082] In this example, the non-connection portion 430 is provided in the third layer 300. Specifically, multiple non-connection portions 430 are disposed in the third wiring layer 320 on the stack-up surface 160, but not in the wiring layer 230. As a result, the heat generated in the signal processing circuit 202 and the image processing circuit 302 is transferred to the non-connection portion 430 and released to the outside of the imaging element 10. Alternatively, the non-connection portions 430 may be disposed alternately in the wiring layer 230 and the third wiring layer 320 on the stack-up surface 160.

[0083] Figure 8 This is a diagram showing an example of a cross-section in the XY direction of the imaging element 10 according to this embodiment. Wherein, for... Figure 5 Common elements are labeled with the same reference numerals, and descriptions are omitted.

[0084] In this example, the non-connecting portion 430 is disposed in the first region 162, and the connecting portion 190 is disposed in the second region 164. In this way, by distributing multiple connecting portions 190 on the outer periphery of the laminated surface 160, the bonding strength between layers can be ensured, while the thermally conductive layer is disposed in the first region 162.

[0085] Figure 9 This is a diagram showing an example of a cross-section in the XY direction of the imaging element 10 according to this embodiment. Wherein, for... Figure 5 Common elements are labeled with the same reference numerals, and descriptions are omitted.

[0086] In this example, with Figure 8 Similarly, non-connection portions 430 are disposed in the first region 162, and connection portions 190 are disposed in the second region 164. However, the arrangement density of non-connection portions 430 is higher than that of connection portions 190. As an example, in the second region 164, two connection portions 190 are arranged diagonally for each third region 166, but in the first region 162, four non-connection portions 430 are arranged for each third region 166. Thus, by arranging the non-connection portions 430 at a higher density than in the second region 164, heat generated in the circuit can be effectively dissipated to the outside.

[0087] Figure 10 This is a diagram showing an example of a cross-section in the XY direction of the imaging element 10 according to this embodiment. Wherein, for... Figure 5 Common elements are labeled with the same reference numerals, and descriptions are omitted.

[0088] In this example, the connecting portion 190 has a rectangular cross-section in the stacking direction, and the non-connecting portion 430 has a circular cross-section in the stacking direction. Furthermore, the distance between adjacent non-connecting portions 430 is shorter than the distance between adjacent connecting portions 190. Thus, by setting the non-connecting portions 430 to have a circular cross-section, finer filling is possible, and the non-connecting portions 430 can be arranged with a higher density.

[0089] Figure 11 This is a diagram showing an example of a cross-section in the XY direction of the imaging element 10 according to this embodiment. Wherein, for... Figure 5 Common elements are labeled with the same reference numerals, and descriptions are omitted.

[0090] In this example, the density of non-connected portions 430 in each of the third regions 166 closer to the center of the stacking surface 160 is greater. The heat generated by the circuit increases towards the center of the circuit and decreases towards the peripheral areas. Thus, by increasing the density of non-connected portions 430 closer to the center of the stacking surface 160 in accordance with the heat generated by the circuit, heat can be dissipated evenly. As a result, heat is evenly transferred to multiple pixels (photoelectric conversion unit 102), thus preventing image quality degradation caused by uneven temperature.

[0091] Figure 12 This is a diagram showing an example of a cross-section in the XZ direction of the imaging element 10 according to this embodiment. Wherein, for... Figure 2 Common elements are labeled with the same reference numerals, and descriptions are omitted.

[0092] In this example, a heat dissipation layer 450 extending in the stacking direction is disposed in the peripheral area corresponding to the invalid pixel. The heat dissipation layer 450 is an example of a thermally conductive layer. The heat dissipation layer 450 is formed of metals such as gold, silver, copper, and aluminum.

[0093] The heat dissipation layer 450 can be multi-layered or a single layer. Alternatively, the heat dissipation layer 450 can be disposed in the peripheral area of ​​the signal processing circuit 202 of the second layer 200, extending from the second wiring layer 220 into the interior of the second substrate 210 in the stacking direction. Alternatively, the heat dissipation layer 450 can also be disposed in the peripheral area of ​​the image processing circuit 302 of the third layer 300, extending from the third wiring layer 320 into the interior of the third substrate 310 in the stacking direction.

[0094] Thus, since the heat dissipation layer 450 is located in the surrounding area, it will not become an obstacle to other elements. In addition, the heat dissipation layer 450 can be formed in the same process as TSV106, so the process will not become complicated.

[0095] Figure 13 This is a diagram showing an example of a cross-section in the XZ direction of the imaging element 10 according to this embodiment. Wherein, for... Figure 2 Common elements are labeled with the same reference numerals, and descriptions are omitted.

[0096] In this example, the heat-conducting plate 460 is located on the negative Z-axis side of the third layer 300. The heat-conducting plate 460 is an example of a heat-conducting layer. Because the heat-conducting plate 460 is located on the negative Z-axis side of the third layer 300, opposite to the pixels located on the positive Z-axis side of the first layer 100, heat is transferred to the heat-conducting plate 460, thereby suppressing heat transfer to the pixels.

[0097] The heat-conducting plate 460 can be directly bonded to the surface of the third substrate 310. The surface of the third substrate 310 can be polished. This improves the flatness of the third substrate 310. In addition, by fixing the heat-conducting plate 460 to the surface of the third substrate 310, the strength of the third substrate 310 can be increased.

[0098] As an example, the heat-conducting plate 460 is a copper plate. Copper plates are easy to ensure flatness, thus ensuring the flatness of the imaging element 10. The heat-conducting plate 460 can also be formed of gold, or other metals such as silver and aluminum.

[0099] The heat-conducting plate 460 can be directly connected to the housing of the imaging device on which the imaging element 10 is mounted. Thus, the heat transferred from the imaging element 10 to the heat-conducting plate 460 can be further transferred to the housing of the imaging device, promoting heat dissipation.

[0100] The heat-conducting plate 460 can cover the entire surface of the third substrate 310, or it can have a surface area larger than the surface area (area in the XY plane) of the third substrate 310. Therefore, especially when using air cooling with a fan or the like, it can improve heat dissipation.

[0101] Figure 14 This is a diagram showing an example of a cross-section in the XZ direction of the imaging element 10 according to this embodiment. Wherein, for... Figure 2 Common elements are labeled with the same reference numerals, and descriptions are omitted.

[0102] In this example, a plurality of uneven regions 470 are formed on the positive Z-axis side of the first substrate 110. The uneven regions 470 are an example of a thermally conductive layer.

[0103] The raised / recessed area 470 is located on the positive Z-axis side of the first substrate 110 in the peripheral area where no pixels are set. Because there is sufficient space in the peripheral area, multiple raised / recessed areas can be easily formed.

[0104] As an example, the uneven region 470 can be formed by a plurality of protrusions in the shape of a triangular pyramid or a cone disposed on the positive Z-axis side of the first substrate 110. Alternatively, the uneven region 470 can also be formed by a plurality of grooves provided on the positive Z-axis side of the first substrate 110. As a result, the surface area of ​​the first substrate 110 is increased, which can promote heat dissipation.

[0105] Additionally, a heat transfer section can be provided to dissipate heat from the heat-conducting layer to the outside of the imaging element 10. One end of the transfer section is connected to the heat-conducting layer, and the other end extends to the outside of the imaging element 10. Thus, the transfer section dissipates heat transferred from the heat-conducting layer to the outside of the imaging element 10. The transfer section can be a slice made of metal such as gold, silver, copper, or aluminum. Alternatively, the transfer section can be one end connected to the pixel (photoelectric conversion unit 102) via a connecting portion 190 or a bonding wire, and the other end extends to the outside of the imaging element 10.

[0106] Figure 15 This is a diagram showing an example of a cross-section in the XZ direction of the imaging element 10 according to this embodiment. Wherein, for... Figure 2 Common elements are labeled with the same reference numerals, and descriptions are omitted.

[0107] In this example, the thermal insulation layer 440 is disposed on the second wiring layer 220. The thermal conductivity of the thermal insulation layer 440 is lower than that of the second wiring layer 220. The thermal insulation layer 440 is formed of alumina, zirconium oxide, or tungsten, etc.

[0108] As an example, the heat insulation layer 440 has an area covering one or more pixels. In this way, by using the heat insulation layer 440 to block the heat generated in the signal processing circuit 202 and the image processing circuit 302, the transfer of heat to the pixel (photoelectric conversion unit 102) can be suppressed.

[0109] exist Figure 15 In this configuration, the heat insulation layer 440 is disposed on both the first wiring layer 120 and the second wiring layer 220, but is not limited to these. The heat insulation layer 440 may also be disposed on either the first wiring layer 120 or the second wiring layer 220. Furthermore, by using the heat insulation layer 440 in conjunction with the heat-conducting layer, it can suppress heat transfer to the pixels and effectively dissipate heat to the outside.

[0110] Figure 16 This is a block diagram illustrating an example configuration of the imaging device 500 according to this embodiment. The imaging device 500 includes an imaging element 10, a control unit 501, a metering unit 503, a recording unit 505, a display unit 506, and a driving unit 514. The imaging lens 520 guides light from the subject to the imaging element 10, causing the image of the subject to be formed on the imaging element 10. Furthermore, the imaging lens 520 can be detached from the imaging device 500.

[0111] The imaging lens 520 consists of multiple optical lens groups, including a focus-adjusting lens (focusing lens), and an aperture, which allows light from the subject to be imaged near the focal plane. Furthermore, in Figure 16 The image shows a virtual lens positioned near the pupil of the imaging lens 520.

[0112] The drive unit 514 moves the position of the imaging lens 520. More specifically, the drive unit 514 moves the optical lens group of the imaging lens 520 to change the focus position. In addition, it drives the aperture inside the imaging lens 520 to control the amount of light incident on the imaging element 10.

[0113] Image element 10 is the same as Figures 1-15 The imaging element 10 described in connection with this is the same. The imaging element 10 performs photoelectric conversion on the received light to generate a signal, and outputs the generated signal to the image processing unit 511 of the control unit 501. The image processing unit 511 performs various image processing on the signal output from the imaging element 10 to generate still image data and moving image data. For example, the image processing unit 511 performs image processing such as grayscale conversion processing, color interpolation processing, and compression processing.

[0114] The recording unit 505 contains recording media such as a memory card. Image data and control programs are recorded in the recording unit 505. The writing of data to and reading data from the recording unit 505 is controlled by the control unit 501. The display unit 506 displays information related to shooting, such as the image based on the image data, shutter speed, aperture value, and menu screens. The operation unit 508 includes a release button, a power switch, switches for switching various modes, and other setting switches, and outputs signals based on the photographer's operations to the control unit 501.

[0115] The metering unit 503 detects the brightness distribution of the subject and scene before generating a series of shooting sequences of image data. The metering unit 503 includes, for example, a sensor with approximately 1 megapixel resolution. The arithmetic unit 512 of the control unit 501 calculates the brightness of the subject and scene based on the output of the metering unit 503.

[0116] The arithmetic unit 512 determines the shutter speed, aperture value, and ISO sensitivity based on the calculated brightness distribution. The metering unit 503 can also be used in the imaging element 10. In addition, the arithmetic unit 512 also performs various calculations to operate the imaging device 500. A portion of the control unit 501 can also be mounted in the imaging element 10.

[0117] The control unit 501 consists of processors such as CPU, FPGA, and ASIC, and memories such as ROM and RAM, and controls various parts of the imaging device 500 based on the control program. For example, the control unit 501 supplies signals to the imaging element 10 to control the operation of the imaging element 10.

[0118] The present invention has been described above using embodiments, but the technical scope of the present invention is not limited to the scope described in the above embodiments. It will be apparent to those skilled in the art that various changes or modifications can be made to the above embodiments. It is also apparent that forms obtained by making such changes or modifications according to the claims can be included within the technical scope of the present invention.

[0119] It should be noted that the execution order of actions, sequences, steps, and stages in the apparatus, systems, programs, and methods shown in the claims, description, and figures can be implemented in any order, unless specifically stated as "before," "prior to," etc., and the output of a previous process is not used in a subsequent process. Even if the flow of actions in the claims, description, and figures is described for convenience using terms such as "firstly," "next," etc., it does not mean that they must be performed in that order.

[0120] Explanation of reference numerals in the attached figures

[0121] 10: Imaging element; 100: First layer; 101: Microlens; 102: Photoelectric conversion unit; 103: Passivation film; 104: Color filter; 105: Transistor; 106: TSV; 110: First substrate; 120: First wiring layer; 150: Lamination surface; 160: Lamination surface; 162: First region; 164: Second region; 166: Third region; 180: Wiring; 190: Connector; 200: Second layer; 202: Signal processing circuit; 210: Second substrate; 220: Second wiring layer; 230: Wiring layer; 300: Third layer; 302: Image. Processing circuit, 310: third substrate, 320: third wiring layer, 410: heat-conducting layer, 412: first heat-conducting layer, 414: second heat-conducting layer, 420: first heat-conducting plate, 421: second heat-conducting plate, 422: connecting part, 430: non-connecting part, 440: heat insulation layer, 450: heat dissipation layer, 460: heat-conducting plate, 470: uneven area, 500: imaging device, 501: control unit, 503: metering unit, 505: recording unit, 506: display unit, 508: operation unit, 511: image processing unit, 512: calculation unit, 514: driving unit, 520: imaging lens.

Claims

1. A shooting element, comprising: The first layer has a first substrate, on which a photoelectric conversion unit for converting light into charge is disposed; The second layer, which is a layer stacked on top of the first layer, has a second substrate, on which a first circuit is disposed to perform first signal processing on a first signal obtained based on the charge converted by the photoelectric conversion unit; and The third layer, which is stacked with the first layer, has a third substrate and a thermally conductive first component. A second circuit is disposed on the third substrate to perform second signal processing on a second signal. The second signal is a signal output from the first circuit and is a signal after the first circuit has performed the first signal processing on the first signal. The first component is disposed between the second substrate and the third substrate in a first direction in which the first and second layers are stacked, and extends along a second direction intersecting the first direction. The second layer is disposed between the first layer and the third layer in the first direction. The second layer has a thermally conductive second component, which is disposed between the second substrate and the third substrate in the first direction and extends along the second direction. The thermal conductivity of the first component is higher than that of the second component.

2. The imaging element according to claim 1, wherein, The area of ​​the first component is larger than the area of ​​the second component.

3. The imaging element according to claim 2, wherein, The first component is disposed between the first circuit and the third substrate in the first direction.

4. The imaging element according to claim 2, wherein, The first component is made of copper.

5. The imaging element according to claim 2, wherein, The device includes a connecting portion that electrically connects the first substrate and the second substrate, and has conductive components arranged to face each other in the first direction.

6. The imaging element according to claim 5, wherein, The conductive component is disposed between the photoelectric conversion unit and the second substrate in the first direction.

7. The imaging element according to claim 5, wherein, The first signal is output from the first substrate to the first circuit via the conductive component.

8. The imaging element according to claim 5, wherein, The conductive component is made of copper.

9. The imaging element according to claim 2, wherein, The second substrate is provided with a control circuit that controls the accumulation time for accumulating the charge converted by the photoelectric conversion unit.

10. The imaging element according to claim 1, wherein, A third component having thermal conductivity is disposed between the first component and the second component in the first direction.

11. The imaging element according to claim 10, wherein, The third component is connected to the first component.

12. The imaging element according to claim 11, wherein, The third component is connected to the second component.

13. The imaging element according to claim 10, wherein, The first component is disposed between the first circuit and the third substrate in the first direction.

14. The imaging element according to claim 10, wherein, The first component is made of copper.

15. The imaging element according to claim 10, wherein, The device includes a connecting portion that electrically connects the first substrate and the second substrate, and has conductive components arranged to face each other in the first direction.

16. The imaging element according to claim 15, wherein, The conductive component is disposed between the photoelectric conversion unit and the second substrate in the first direction.

17. The imaging element according to claim 15, wherein, The first signal is output from the first substrate to the first circuit via the conductive component.

18. The imaging element according to claim 15, wherein, The conductive component is made of copper.

19. The imaging element according to claim 10, wherein, The second substrate is provided with a control circuit that controls the accumulation time for accumulating the charge converted by the photoelectric conversion unit.

20. The imaging element according to claim 1, wherein, The first component is disposed between the first circuit and the third substrate in the first direction.

21. The imaging element according to claim 1, wherein, The first component is made of copper.

22. The imaging element according to claim 1, wherein, The device includes a connecting portion that electrically connects the first substrate and the second substrate, and has conductive components arranged to face each other in the first direction.

23. The imaging element according to claim 22, wherein, The conductive component is disposed between the photoelectric conversion unit and the second substrate in the first direction.

24. The imaging element according to claim 22, wherein, The first signal is output from the first substrate to the first circuit via the conductive component.

25. The imaging element according to claim 22, wherein, The conductive component is made of copper.

26. The imaging element according to claim 1, wherein, The second substrate is provided with a control circuit that controls the accumulation time for accumulating the charge converted by the photoelectric conversion unit.

27. A shooting device comprising the shooting element as described in any one of claims 1 to 26.

28. The imaging device according to claim 27, wherein, It includes a drive unit that drives an optical system that emits light toward the imaging element.

29. The imaging device according to claim 27, wherein, It includes a pixel processing unit, which is electrically connected to the imaging element and generates pixel data.

Images