Photodetector and electronic equipment

Abstract

Provided is a light detecting device in which a deterioration in contact between connection pads is suppressed. This light detecting device comprises at least two semiconductor layers, and a wiring layer on one side in a stacking direction and a wiring layer on the other side in the stacking direction, the wiring layers being interposed between the semiconductor layers, each including an insulating film and connection pads provided in the insulating film, and being electrically joined to one another by surfaces of the connection pads being joined to one another, wherein: a semiconductor layer on a light-incident surface side, among the at least two semiconductor layers, includes a photoelectric conversion region; the insulating film includes a first insulating film and a second insulating film which comprises a material having a higher rigidity than a material forming the first insulating film, and which penetrates through the first insulating film in a stacking direction; and the second insulating film is provided between the connection pads and at least one of the semiconductor layers.

Description

[Technical Field]

[0001] The present technology (technology related to the present disclosure) relates to a photodetector and an electronic device, and in particular to a stacked-type photodetector and an electronic device. [Background technology]

[0002] In stacked image sensors, wafers are sometimes directly bonded together using hybrid bonding, in which metal connection pads formed on wiring layers are bonded together to electrically bond the wafers together (see, for example, Patent Document 1).

[0003] Furthermore, in order to suppress an increase in parasitic capacitance between wirings, a low dielectric constant insulating material may be used as an insulating film for a wiring layer (for example, Patent Document 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2019-110260 [Patent Document 2] Japanese Patent Application Laid-Open No. 2015-76502 Summary of the Invention [Problem to be solved by the invention]

[0005] The connection pads are heat-treated after being stacked together. This heat treatment causes the metal that makes up the connection pad to expand, thereby preventing the contact between the pads from deteriorating. The dimensions of such connection pads are becoming smaller as devices become smaller. As the dimensions of the connection pads become smaller, the capacitance of the metal that makes up the connection pad decreases. The reduced capacitance of the metal reduces the amount of expansion due to heat treatment. Low-dielectric-constant insulating materials are also known to have a lower Young's modulus than, for example, silicon oxide.

[0006] The present technology aims to provide a light-detecting device and an electronic device in which deterioration of contact between connection pads is suppressed. [Means for solving the problem]

[0007] A photodetector according to one aspect of the present technology comprises at least two semiconductor layers, and a wiring layer on one side of the stacking direction and a wiring layer on the other side of the stacking direction, interposed between the semiconductor layers, each including an insulating film and a connection pad provided on the insulating film, and electrically coupled to each other by joining the surfaces of the connection pads together, wherein the semiconductor layer on the light incident surface side of the at least two semiconductor layers has a photoelectric conversion region, and the insulating film includes a first insulating film and a second insulating film made of a material more rigid than a material constituting the first insulating film and penetrating the first insulating film in the stacking direction, and the second insulating film is provided between the connection pad and at least one of the semiconductor layers.

[0008] A photodetector according to another aspect of the present technology includes at least two semiconductor layers, and a wiring layer on one side of the stacking direction and a wiring layer on the other side of the stacking direction, interposed between the semiconductor layers, each including an insulating film and a connection pad provided on the insulating film, and electrically coupled to each other by joining the surfaces of the connection pads together, wherein the semiconductor layer on the light incident surface side of the at least two semiconductor layers has a photoelectric conversion region, and at least one of the connection pads has a first portion made of a first metal and constituting the surface of the connection pad, and a second portion made of a second metal provided between the first portion and the insulating film and more easily plastically deformed than the first metal.

[0009] A photodetector according to another aspect of the present technology includes at least two semiconductor layers, and a wiring layer on one side of the stacking direction and a wiring layer on the other side of the stacking direction, interposed between the semiconductor layers, each including an insulating film and a connection pad provided on the insulating film, and electrically coupled to each other by joining the surfaces of the connection pads together, wherein the semiconductor layer on the light incident surface side of the at least two semiconductor layers has a photoelectric conversion region, and the linear expansion coefficient of a material constituting a third portion of the insulating film, which is a portion adjacent to a side surface of the connection pad, is smaller than the linear expansion coefficient of a material constituting a fourth portion, which is a portion adjacent to a bottom surface of the connection pad.

[0010] An electronic device according to an aspect of the present technology includes the light detection device and an optical system that forms an image light from a subject on the light detection device. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a chip layout diagram showing an example of a configuration of a photodetector according to a first embodiment of the present technology. [Figure 2] 1 is a block diagram showing an example of the configuration of a photodetector according to a first embodiment of the present technology; [Figure 3] 1 is an equivalent circuit diagram of a pixel of a photodetector according to a first embodiment of the present technology. [Figure 4A] 1 is a longitudinal sectional view of a photodetector according to a first embodiment of the present technology. [Figure 4B] FIG. 4B is a partially enlarged view showing a main part of FIG. 4A. [Figure 5A] 5A to 5C are cross-sectional views illustrating steps in a method for manufacturing a photodetector according to a first embodiment of the present technology. [Figure 5B] 5B is a cross-sectional view showing a process subsequent to FIG. 5A. [Figure 5C] 5B is a cross-sectional view showing a process subsequent to FIG. 5B. [Figure 5D] 5D is a cross-sectional view showing a process subsequent to FIG. 5C. [Figure 5E] FIG. 5D is a cross-sectional view showing a process subsequent to FIG. 5D. [Figure 5F] 5B is a cross-sectional view showing a process subsequent to FIG. 5E. [Figure 5G] FIG. 5C is a cross-sectional view showing a process subsequent to FIG. 5F. [Figure 5H] FIG. 5C is a cross-sectional view showing a process subsequent to FIG. 5G. [Figure 5I] 5H. FIG. [Figure 5J] 5I. FIG. [Figure 5K] 5J. FIG. [Figure 5L] FIG. 5K is a cross-sectional view showing a process subsequent to FIG. [Figure 5M] FIG. 5B is a cross-sectional view showing a process subsequent to FIG. 5L. [Figure 5N] 5B is a cross-sectional view showing a process subsequent to FIG. 5M. [Figure 6] FIG. 10 is a partially enlarged view showing a main part of a longitudinal cross section of a light detection device according to another aspect of the first embodiment of the present technology. [Figure 7] 10 is a partially enlarged view showing a main part of a vertical cross section of a photodetector according to a first modified example of the first embodiment of the present technology. FIG. [Figure 8A] 5A to 5C are cross-sectional views illustrating steps in a method for manufacturing a photodetector according to a first modified example of the first embodiment of the present technology. [Figure 8B] 8B is a cross-sectional view showing a process subsequent to FIG. 8A. [Figure 8C] 8C is a cross-sectional view showing a process subsequent to FIG. 8B. [Figure 8D] 8D is a cross-sectional view showing a process subsequent to FIG. 8C. [Figure 9] FIG. 10 is a longitudinal sectional view of a photodetector according to a second embodiment of the present technology. [Figure 10] 10 is an explanatory diagram for explaining a configuration of a connection pad included in a light detection device according to a second embodiment of the present technology. FIG. [Figure 11A] 10A to 10C are cross-sectional views illustrating steps in a method for manufacturing a photodetector according to a second embodiment of the present technology. [Figure 11B] 11B is a cross-sectional view showing a process subsequent to FIG. 11A. [Figure 11C] 11B is a cross-sectional view showing a process subsequent to FIG. 11B. [Figure 11D] 11D is a cross-sectional view showing a process subsequent to FIG. 11C. [Figure 11E] 11D and 11C are cross-sectional views showing the process steps subsequent to FIG. [Figure 11F] 11B is a cross-sectional view showing a process subsequent to FIG. 11E. [Figure 12] 10 is an explanatory diagram for explaining a configuration of a connection pad included in a light detection device according to a first modified example of the second embodiment of the present technology. FIG. [Figure 13] 13 is an explanatory diagram for explaining a configuration of a connection pad included in a light detection device according to a second modification of the second embodiment of the present technology. FIG. [Figure 14] FIG. 10 is a longitudinal sectional view of a photodetector according to a third embodiment of the present technology. [Figure 15] 10 is an explanatory diagram for explaining the configuration of an insulating film around a connection pad included in a photodetector according to a third embodiment of the present technology. FIG. [Figure 16A] 10A to 10C are cross-sectional views illustrating steps in a method for manufacturing a photodetector according to a third embodiment of the present technology. [Figure 16B] 16B is a cross-sectional view showing a process subsequent to FIG. 16A. [Figure 16C] 16B is a cross-sectional view showing a process subsequent to FIG. 16B. [Figure 16D] 16D is a cross-sectional view showing a process subsequent to FIG. 16C. [Figure 16E] FIG. 16D is a cross-sectional view showing the process subsequent to FIG. 16D. [Figure 16F] 16B is a cross-sectional view showing the process subsequent to FIG. 16E. [Figure 17] 13 is an explanatory diagram for explaining a configuration of a contact layer included in a photodetector according to a first modified example of the third embodiment of the present technology. FIG. [Figure 18A] 13A to 13C are cross-sectional views illustrating steps in a method for manufacturing a photodetector according to a first modified example of the third embodiment of the present technology. [Figure 18B] 18B is a cross-sectional view showing a process subsequent to FIG. 18A. [Figure 18C] 18B is a cross-sectional view showing the process subsequent to FIG. 18B. [Figure 18D] 18D is a cross-sectional view showing a process subsequent to FIG. 18C. [Figure 18E] 18D and 18C are cross-sectional views showing the process steps subsequent to FIG. 18D. [Figure 18F] 18E is a cross-sectional view showing the process following FIG. 18E. [Figure 18G] 18F. FIG. [Figure 19] FIG. 10 is a diagram showing a schematic configuration of an electronic device according to a fourth embodiment of the present technology. [Figure 20] 1 is a block diagram showing an example of a schematic configuration of a vehicle control system; [Figure 21] FIG. 2 is an explanatory diagram showing an example of the installation positions of an outside-vehicle information detection unit and an imaging unit. [Figure 22] FIG. 1 is a diagram illustrating an example of a schematic configuration of an endoscopic surgery system. [Figure 23] FIG. 2 is a block diagram showing an example of the functional configuration of a camera head and a CCU. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, preferred embodiments for carrying out the present technology will be described with reference to the drawings. Note that the embodiments described below are examples of typical embodiments of the present technology, and the scope of the present technology should not be interpreted as being narrow.

[0013] In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic, and the relationship between thickness and planar dimensions, the thickness ratio of each layer, etc., may differ from the actual ones. Therefore, specific thicknesses and dimensions should be determined by taking into consideration the following explanation. Furthermore, it goes without saying that the drawings may include parts with different dimensional relationships and ratios.

[0014] Furthermore, the embodiments described below are merely examples of devices and methods for embodying the technical idea of ​​the present technology, and the technical idea of ​​the present technology does not specify the materials, shapes, structures, arrangements, etc. of the components to those described below. The technical idea of ​​the present technology can be modified in various ways within the technical scope defined by the claims.

[0015] The explanation will be given in the following order. 1. First embodiment 2. Second embodiment 3. Third embodiment 4. Fourth embodiment Application examples for electronic devices Mobile application example Application example to endoscopic surgery system

[0016] [First embodiment] In this first embodiment, an example in which the present technology is applied to a photodetector device that is a back-illuminated CMOS (Complementary Metal Oxide Semiconductor) image sensor will be described.

[0017] <Overall configuration of the photodetector> First, the overall configuration of the photodetector 1 will be described. As shown in Fig. 1, the photodetector 1 according to the first embodiment of the present technology is mainly composed of a semiconductor chip 2 having a rectangular two-dimensional planar shape when viewed in plan. That is, the photodetector 1 is mounted on the semiconductor chip 2. As shown in Fig. 19, the photodetector 1 captures image light (incident light 106) from an object via an optical system (optical lens) 102, converts the amount of incident light 106 formed on an imaging surface into an electrical signal on a pixel-by-pixel basis, and outputs the signal as a pixel signal.

[0018] As shown in FIG. 1, the semiconductor chip 2 on which the photodetector 1 is mounted includes a square pixel region 2A located in the center of a two-dimensional plane including an X direction and a Y direction that intersect with each other, and a peripheral region 2B located outside the pixel region 2A so as to surround the pixel region 2A.

[0019] The pixel region 2A is a light receiving surface that receives light collected by, for example, the optical system 102 shown in FIG. 19. In the pixel region 2A, a plurality of pixels 3 are arranged in a matrix on a two-dimensional plane including the X direction and the Y direction. In other words, the pixels 3 are repeatedly arranged in each of the X direction and the Y direction that intersect with each other on the two-dimensional plane. In this embodiment, as an example, the X direction and the Y direction are orthogonal to each other. Furthermore, the direction orthogonal to both the X direction and the Y direction is the Z direction (thickness direction).

[0020] 1, a plurality of bonding pads 14 are arranged in the peripheral region 2B. Each of the plurality of bonding pads 14 is arranged, for example, along each of the four sides in a two-dimensional plane of the semiconductor chip 2. Each of the plurality of bonding pads 14 is an input / output terminal used when electrically connecting the semiconductor chip 2 to an external device.

[0021] <Logic circuit> 2, the semiconductor chip 2 includes a logic circuit 13 including a vertical drive circuit 4, a column signal processing circuit 5, a horizontal drive circuit 6, an output circuit 7, and a control circuit 8. The logic circuit 13 is configured of a CMOS (Complenentary MOS) circuit having, as field effect transistors, for example, n-channel conductivity type MOSFETs (Metal Oxide Semiconductor Field Effect Transistors) and p-channel conductivity type MOSFETs.

[0022] The vertical drive circuit 4 is configured with, for example, a shift register. The vertical drive circuit 4 sequentially selects desired pixel drive lines 10, supplies pulses to the selected pixel drive lines 10 for driving the pixels 3, and drives each pixel 3 row by row. That is, the vertical drive circuit 4 sequentially selects and scans each pixel 3 in the pixel region 2A row by row in the vertical direction, and supplies pixel signals from the pixels 3 based on signal charges generated by the photoelectric conversion elements of each pixel 3 in accordance with the amount of light received to the column signal processing circuit 5 via vertical signal lines 11.

[0023] The column signal processing circuits 5 are arranged, for example, for each column of pixels 3, and perform signal processing such as noise removal for each pixel column on signals output from one row of pixels 3. For example, the column signal processing circuits 5 perform signal processing such as CDS (Correlated Double Sampling) and AD (Analog-Digital) conversion to remove fixed pattern noise specific to the pixels. A horizontal selection switch (not shown) is provided at the output stage of the column signal processing circuit 5 and connected between the output stage and the horizontal signal line 12.

[0024] The horizontal drive circuit 6 is configured with, for example, a shift register. The horizontal drive circuit 6 sequentially outputs horizontal scanning pulses to the column signal processing circuits 5, thereby selecting each of the column signal processing circuits 5 in turn and causing each column signal processing circuit 5 to output a pixel signal that has undergone signal processing to a horizontal signal line 12.

[0025] The output circuit 7 performs signal processing on the pixel signals sequentially supplied from each of the column signal processing circuits 5 through the horizontal signal line 12, and outputs the processed signals. Examples of signal processing that can be used include buffering, black level adjustment, column variation correction, and various types of digital signal processing.

[0026] Based on the vertical synchronization signal, horizontal synchronization signal, and master clock signal, the control circuit 8 generates clock signals and control signals that serve as references for the operations of the vertical drive circuit 4, column signal processing circuit 5, horizontal drive circuit 6, etc. Then, the control circuit 8 outputs the generated clock signals and control signals to the vertical drive circuit 4, column signal processing circuit 5, horizontal drive circuit 6, etc.

[0027] <Pixels> 3 is an equivalent circuit diagram showing an example of the configuration of pixel 3. Pixel 3 includes a photoelectric conversion element PD, a charge accumulation region (floating diffusion) FD that accumulates (holds) signal charges photoelectrically converted by this photoelectric conversion element PD, and a transfer transistor TR that transfers the signal charges photoelectrically converted by this photoelectric conversion element PD to the charge accumulation region FD. Pixel 3 also includes a readout circuit 15 electrically connected to the charge accumulation region FD.

[0028] The photoelectric conversion element PD generates a signal charge according to the amount of light received. The photoelectric conversion element PD also temporarily accumulates (holds) the generated signal charge. The cathode side of the photoelectric conversion element PD is electrically connected to the source region of the transfer transistor TR, and the anode side is electrically connected to a reference potential line (e.g., ground). For example, a photodiode is used as the photoelectric conversion element PD.

[0029] The drain region of the transfer transistor TR is electrically connected to the charge storage region FD, and the gate electrode of the transfer transistor TR is electrically connected to a transfer transistor driving line among the pixel driving lines 10 (see FIG. 2).

[0030] The charge storage region FD temporarily stores and holds the signal charge transferred from the photoelectric conversion element PD via the transfer transistor TR.

[0031] The readout circuit 15 reads out the signal charge accumulated in the charge accumulation region FD and outputs a pixel signal based on the signal charge. The readout circuit 15 includes, but is not limited to, pixel transistors, such as an amplification transistor AMP, a selection transistor SEL, and a reset transistor RST. These transistors (AMP, SEL, RST) are configured as MOSFETs having, for example, a gate insulating film made of a silicon oxide film (SiO2 film), a gate electrode, and a pair of main electrode regions that function as a source region and a drain region. These transistors may also be MISFETs (Metal Insulator Semiconductor FETs) whose gate insulating film is made of a silicon nitride film (Si3N4 film) or a stacked film of a silicon nitride film, a silicon oxide film, or the like.

[0032] The amplifier transistor AMP has a source region electrically connected to the drain region of the select transistor SEL, a drain region electrically connected to the power supply line Vdd and the drain region of the reset transistor RST, and a gate electrode electrically connected to the charge storage region FD and the source region of the reset transistor RST.

[0033] The selection transistor SEL has a source region electrically connected to the vertical signal line 11 (VSL), a drain electrically connected to the source region of the amplification transistor AMP, and a gate electrode electrically connected to a selection transistor drive line among the pixel drive lines 10 (see FIG. 2).

[0034] The reset transistor RST has a source region electrically connected to the charge storage region FD and the gate electrode of the amplifier transistor AMP, and a drain region electrically connected to the power supply line Vdd and the drain region of the amplifier transistor AMP. The gate electrode of the reset transistor RST is electrically connected to a reset transistor drive line among the pixel drive lines 10 (see FIG. 2).

[0035] <<Specific configuration of the photodetector>> Next, a specific configuration of the photodetector 1 will be described with reference to FIGS. 4A and 4B.

[0036] <Layer structure of photodetector> 4A, the photodetector 1 (semiconductor chip 2) has a layered structure in which a light-collecting layer 90, a first semiconductor layer 20, a first wiring layer 30, a second wiring layer 40, a second semiconductor layer 50, a third wiring layer 60, a fourth wiring layer 70, and a third semiconductor layer 80 are layered in this order. In the example shown in FIG. 4A, the photodetector 1 has three semiconductor layers: the first semiconductor layer 20, the second semiconductor layer 50, and the third semiconductor layer 80.

[0037] The light-collecting layer 90 has a laminated structure in which, for example, a color filter 91 and an on-chip lens 92 are laminated in this order from the second surface S2 side of the first semiconductor layer 20, although this is not limited thereto. The first semiconductor layer 20 has a photoelectric conversion region (described later), and one surface thereof is a first surface S1 and the other surface thereof is a second surface S2 that is a light incident surface. The first wiring layer 30 is overlaid on the first surface S1 of the first semiconductor layer 20. The second wiring layer 40 is overlaid on the surface of the first wiring layer 30 opposite to the surface on the first semiconductor layer 20 side. The second semiconductor layer 50 has a transistor, and one surface thereof is a third surface S3 and the other surface is a fourth surface S4, with the third surface S3 being overlaid on the surface of the second wiring layer 40 opposite to the surface on the first wiring layer 30 side. The third wiring layer 60 is overlaid on the fourth surface S4 of the second semiconductor layer 50. The fourth wiring layer 70 is superimposed on the surface of the third wiring layer 60 opposite to the surface on the second semiconductor layer 50 side. The fifth surface S5 of the third semiconductor layer 80 is superimposed on the surface of the fourth wiring layer 70 opposite to the surface on the third wiring layer 60 side.

[0038] Here, the first surface S1 of the first semiconductor layer 20 is sometimes referred to as the element formation surface or main surface, and the second surface S2 of the first semiconductor layer 20 is sometimes referred to as the light incident surface or back surface. The third surface S3 of the second semiconductor layer 50 is sometimes referred to as the element formation surface or main surface, and the fourth surface S4 of the second semiconductor layer 50 is sometimes referred to as the back surface. The fifth surface S5 of the third semiconductor layer 80 is sometimes referred to as the element formation surface or main surface, and the surface opposite to the fifth surface S5 is sometimes referred to as the back surface. Here, the third surface S3 and the fifth surface S5 may have irregularities as shown in FIG. 4A.

[0039] <First semiconductor layer> The first semiconductor layer 20 is made of a semiconductor substrate. The first semiconductor layer 20 is made of, for example, a single crystal silicon substrate, although not limited thereto. The first semiconductor layer 20 exhibits a first conductivity type, for example, p-type. The first semiconductor layer 20 is the semiconductor layer on the light incident surface side of the above-mentioned three semiconductor layers. More specifically, the first semiconductor layer 20 is the semiconductor layer located closest to the light incident surface side of the photodetector 1 of the above-mentioned three semiconductor layers.

[0040] The first semiconductor layer 20 has a photoelectric conversion region 20a for each pixel 3. The first semiconductor layer 20 has, for example, an island-shaped photoelectric conversion region 20a partitioned by an isolation region 20b for each pixel 3. The number of pixels 3 is not limited to that shown in FIG. 4A. The isolation region 20b has, for example, a trench structure in which an isolation groove is formed in the first semiconductor layer 20 and an insulating film is buried in the isolation groove, although this is not limited thereto. In the example shown in FIG. 4A, an insulating film and a metal are buried in the isolation groove.

[0041] Although not shown, the photoelectric conversion region 20a has a well region of a first conductivity type, for example, p-type, and a semiconductor region (photoelectric conversion portion) of a second conductivity type, for example, n-type, buried inside the well region. The photoelectric conversion element PD shown in FIG. 3 is configured in the photoelectric conversion region 20a including the well region and the photoelectric conversion portion of the first semiconductor layer 20. A transistor T1 may also be provided in the photoelectric conversion region 20a. Furthermore, the photoelectric conversion region 20a may also be provided with a charge accumulation region (not shown) that is a semiconductor region of the second conductivity type, for example, n-type.

[0042] <First and second wiring layers> The first wiring layer 30 and the second wiring layer 40 are interposed between the semiconductor layers, more specifically, between the first semiconductor layer 20 and the second semiconductor layer 50. One of the first wiring layer 30 and the second wiring layer 40 is a wiring layer on one side in the stacking direction, and the other is a wiring layer on the other side in the stacking direction.

[0043] The first wiring layer 30 includes an insulating film 31, wiring 32, first connection pads 33, and vias (contacts) 34. The wiring 32 and the first connection pads 33 are stacked with the insulating film 31 interposed therebetween as shown in the figure. The surface of the first connection pads 33 faces the surface of the first wiring layer 30 opposite the first semiconductor layer 20 side. The vias 34 connect the first semiconductor layer 20 and the wiring 32, between the wirings 32, and between the wiring 32 and the first connection pads 33, etc. Furthermore, the wiring 32 and the first connection pads 33 may be made of, but are not limited to, copper, for example, and formed by a damascene method.

[0044] The insulating film 31 includes a first insulating film 35 made of a first material and a second insulating film 36 made of a second material. When the first insulating film 35 and the second insulating film 36 are not distinguished, they are simply referred to as the insulating film 31. The second material will be described first. The second material is a material having a higher dielectric constant and higher rigidity than the first material. The second material is, for example, silicon dioxide (SiO2). The first material is a low-k insulating material having a lower dielectric constant than the second material and lower rigidity than the first material. Here, the second material is described as silicon dioxide, so the first material is an insulating material having a lower dielectric constant and lower rigidity than a silicon dioxide film. The first material is, for example, a carbon-containing silicon dioxide film (SiOC) or a SiCOH film. The first material may be not only a mixture of the organic and inorganic materials described above, but also other inorganic or organic materials. Examples of inorganic materials include fluorine-doped silicon dioxide (SiOF) and hydrogenated silsesquioxane (HSQ). Examples of organic materials include parylene and polyallyl ether. Examples of composite materials of organic and inorganic materials other than carbon-containing silicon oxide (SiOC) and SiCOH include methylated silsesquioxane (MSQ). The first material may also be a porous insulating material made by introducing pores into the insulating film. Specifically, the dielectric constant of the insulating film can be reduced by reducing the film density, for example, through heat or drying. Furthermore, by forming the first insulating film 35 from the first material, an increase in inter-wiring capacitance can be suppressed. Suppressing the increase in inter-wiring capacitance enables high-speed operation of semiconductor elements, faster signal transmission, and reduced power consumption. Hereinafter, the terms "first material" and "second material" refer to the first and second materials described above, unless otherwise defined.

[0045] The second wiring layer 40 includes an insulating film 41, wiring 42, second connection pads 43, and vias (contacts) 44. The wiring 42 and the second connection pads 43 are stacked with the insulating film 41 interposed therebetween as shown in the figure. The surface of the second connection pads 43 faces the surface of the second wiring layer 40 opposite the second semiconductor layer 50 side. The vias 44 connect the second semiconductor layer 50 and the wiring 42, the wirings 42 to each other, and the wiring 42 and the second connection pads 43, etc. Furthermore, the wiring 42 and the second connection pads 43 may be made of, but are not limited to, copper, for example, and may be formed by a damascene method.

[0046] The surface of the first connection pad 33 is bonded to the surface of the second connection pad 43. By bonding the surfaces of the connection pads together in this manner, the first wiring layer 30 and the second wiring layer 40 are electrically coupled to each other.

[0047] The insulating film 41 includes a first insulating film 45 made of a first material and a second insulating film 46 made of a second material. When the first insulating film 45 and the second insulating film 46 are not distinguished from each other, they are simply referred to as the insulating film 41.

[0048] <Second semiconductor layer> The second semiconductor layer 50 is made of a semiconductor substrate. The second semiconductor layer 50 is made of, for example, a single crystal silicon substrate, although not limited thereto. The second semiconductor layer 50 exhibits a first conductivity type, for example, p-type. A transistor T2 is provided in the second semiconductor layer 50. Furthermore, the second semiconductor layer 50 is provided with through electrodes 51 and 52 that penetrate the second semiconductor layer 50.

[0049] <Third and fourth wiring layers> The third wiring layer 60 and the fourth wiring layer 70 are interposed between the semiconductor layers, more specifically, between the second semiconductor layer 50 and the third semiconductor layer 80. One of the third wiring layer 60 and the fourth wiring layer 70 is a wiring layer on one side in the stacking direction, and the other is a wiring layer on the other side in the stacking direction.

[0050] 4A, the third wiring layer 60 includes an insulating film 61, a wiring 62, and a third connection pad 63. The wiring 62 and the third connection pad 63 are stacked with the insulating film 61 interposed therebetween as shown. As shown in FIG. 4B, the surface 63S of the third connection pad 63 faces the surface of the third wiring layer 60 opposite to the second semiconductor layer 50 side. The wiring 62 and the third connection pad 63 may be made of, for example, copper and formed by a damascene method, although this is not limited thereto.

[0051] As shown in FIG. 4A, the fourth wiring layer 70 includes an insulating film 71, wiring 72, fourth connection pads 73, and vias (contacts) 74. The wiring 72 and the fourth connection pads 73 are stacked with the insulating film 71 interposed therebetween. As shown in FIG. 4B, the surface 73S of the fourth connection pad 73 faces the surface of the fourth wiring layer 70 opposite the third semiconductor layer 80 side. The vias 74 connect the third semiconductor layer 80 and the wiring 72, the wiring 72 to each other, and the wiring 72 and the fourth connection pad 73, etc. Furthermore, the wiring 72 and the fourth connection pad 73 may be made of, but are not limited to, copper, for example, and may be formed by a damascene method.

[0052] The surface 63S of the third connection pad 63 is joined to the surface 73S of the fourth connection pad 73. By joining the surfaces of the connection pads in this manner, the third wiring layer 60 and the fourth wiring layer 70 are electrically coupled to each other.

[0053] The insulating film 61 includes a first insulating film 65 made of a first material and a second insulating film 66 made of a second material. When the first insulating film 65 and the second insulating film 66 are not distinguished from each other, they are simply referred to as the insulating film 61. As shown in FIGS. 4A and 4B , the second insulating film 66 made of the second material penetrates the first insulating film 65 made of the first material in the stacking direction. More specifically, the second insulating film 66 made of the second material has a columnar portion (hereinafter also referred to as a column P) extending along the stacking direction, and the portion of the second insulating film 66 constituting the column P penetrates the first insulating film 65 made of the first material in the stacking direction. Here, the stacking direction refers to the direction in which the semiconductor layer, the wiring layer, the first insulating film 65, the second insulating film 66, etc. are stacked. Furthermore, the portion of the second insulating film 66 constituting the column P is provided between the third connection pad 63 and the second semiconductor layer 50. As shown in FIG. 4B, the pillar P extends along the stacking direction, with one end in the stacking direction contacting the third connection pad 63, more specifically contacting the bottom surface 63a of the third connection pad 63, and the other end contacting the second semiconductor layer 50, more specifically contacting the fourth surface S4.

[0054] 4A, the insulating film 71 includes a first insulating film 75 made of a first material and a second insulating film 76 made of a second material. When the first insulating film 75 and the second insulating film 76 are not distinguished from each other, they are simply referred to as the insulating film 71.

[0055] <Third semiconductor layer> The third semiconductor layer 80 is made of a semiconductor substrate. The third semiconductor layer 80 is made of a single-crystal silicon substrate of a first conductivity type, for example, p-type. The third semiconductor layer 80 is provided with a transistor T3.

[0056] <Position for installing pillars> The first insulating films 35, 45, 65, and 75 made of the first material are provided in areas of the wiring layer where the wiring is densely arranged. This makes it possible to suppress an increase in wiring capacitance. To suppress an increase in wiring capacitance, it is preferable to provide the first insulating films 35, 45, 65, and 75 over a wide area. Therefore, the first insulating films 35, 45, 65, and 75 are arranged to occupy a wider area in the horizontal direction of the wiring layer.

[0057] Furthermore, pillars P are provided to prevent insufficient bonding between connection pads. The pillars P are columnar portions of the second insulating film 66 that extend along the stacking direction. By providing the pillars P in this shape, the area occupied by the second insulating film 66 can be reduced in areas where wiring is densely arranged. In this way, the pillars P are provided only in necessary locations.

[0058] <Method for manufacturing a photodetector> 5A to 5N, a method for manufacturing the photodetector 1 will be described below. Note that, in the example of the photodetector 1 shown in FIGS. 4A and 4B, the pillars P are provided in the third wiring layer 60, but here, a method for manufacturing the photodetector 1 will be described for an example in which the pillars P are provided in the second wiring layer 40.

[0059] First, as shown in FIG. 5A, elements such as a transistor T2 are formed on the third surface S3 side of a second semiconductor layer 50w of a first conductivity type, for example, a p-type. Then, a portion of the second wiring layer 40 is formed on the third surface S3. More specifically, a second insulating film 46, a via 44, a through electrode 52, etc. are formed on the third surface S3. The second insulating film 46 shown in FIG. 5A is made of a second material, for example, a passivation film.

[0060] Next, as shown in FIG. 5B, a film 45m made of a first material is laminated on the exposed surface of the second insulating film 46. Then, a resist pattern R1 is formed on the exposed surface of the film 45m using a known lithography technique. Thereafter, using the resist pattern R1 as a mask, the film 45m exposed from the opening R1a of the resist pattern R1 is etched using a known etching technique. This etching forms a hole 45h, as shown in FIG. 5C. Then, the resist pattern R1 is removed.

[0061] Then, as shown in FIG. 5D, a film 46m made of a second material is deposited so as to fill the holes 45h. Then, as shown in FIG. 5E, excess portions of the film 46m are removed by CMP (Chemical Mechanical Polishing). More specifically, the exposed surface of the film 46m is polished by CMP to planarize the exposed surface and remove portions of the film 46m other than those filled in the holes 45h. This forms an insulating film in which different insulating materials are adjacent to each other in a direction perpendicular to the deposition direction.

[0062] Next, as shown in FIG. 5F, a resist pattern R2 is formed on the exposed surface of the insulating film, more specifically, on the exposed surfaces of films 45m and 46m, using a known lithography technique. Then, as shown in FIG. 5G, using the resist pattern R2 as a mask, a known etching technique is used to etch the insulating film exposed through openings R2a in the resist pattern R2. This etching forms openings 42h. Then, the resist pattern R2 is removed.

[0063] Thereafter, as shown in Fig. 5H, a metal film M1m is laminated on the inner wall of the opening 42h and the exposed surface of the insulating film. Then, as shown in Fig. 5I, excess portions of the metal film M1m are removed by CMP. This forms the wiring 42 belonging to the metal layer M1.

[0064] Thereafter, steps similar to those shown in Figures 5B to 5I are repeated for each metal layer. As a result, wiring 42 belonging to metal layers M1 to M4 is formed as shown in Figure 5J. Furthermore, for the layer in which vias 44 are to be provided, steps similar to those shown in Figures 5B to 5E are performed, and then vias 44 are formed by a known method. This completes the formation of the layer immediately preceding the layer in which second connection pads 43 are to be provided.

[0065] Next, as shown in FIG. 5K, a film 45m made of a first material is laminated on the exposed surface of the insulating film, and then a second connection pad 43 is formed. More specifically, after laminating the film 45m, the second connection pad 43 is formed by performing the same processes as those shown in FIGS. 5F to 5I. The second connection pad 43 is embedded in an opening 43h formed in the film 45m. This almost completes the second wiring layer 40. The film 46m is laminated along the lamination direction as shown in the figure. The pillar P is then formed by the laminated film 46m and the portion of the second insulating film 46 made of the second material that is located between the film 46m and the second semiconductor layer 50w.

[0066] Then, as shown in FIG. 5L, the second semiconductor layer 50w on which the second wiring layer 40 is stacked is bonded to a separately prepared first semiconductor layer 20 on which the first wiring layer 30 is stacked. More specifically, the surface of the first wiring layer 30 opposite the first semiconductor layer 20 side and the surface of the second wiring layer 40 opposite the second semiconductor layer 50w side are overlapped and bonded. The bonded first wiring layer 30 to the second semiconductor layer 50w are then heat-treated. This heat treatment expands the metal constituting the first connection pad 33 and the second connection pad 43. A pillar P extends along the stacking direction between the bottom surface 43a of the second connection pad 43 and the third surface S3 of the second semiconductor layer 50. More specifically, one end of the pillar P in the stacking direction contacts the bottom surface 43a of the second connection pad 43, and the other end contacts the third surface S3 of the second semiconductor layer 50. This prevents the pressure generated when the metal constituting the first connection pads 33 and the second connection pads 43 expands from escaping to the insulating film. This prevents the pressure from acting in the intended direction when the metal constituting the first connection pads 33 and the second connection pads 43 expands, causing the connection pads to press against each other and resulting in insufficient bonding between the connection pads. In this way, the surfaces of the first connection pads 33 provided on the first wiring layer 30 and the surfaces of the second connection pads 43 provided on the second wiring layer 40 are bonded to each other.

[0067] Then, backgrinding or the like is performed on the back surface side of the second semiconductor layer 50w to reduce the thickness of the second semiconductor layer 50w. This leaves a portion that will become the second semiconductor layer 50, as shown in FIG. 5M. Then, a third wiring layer 60 is laminated on the fourth surface S4 side of the second semiconductor layer 50. Thereafter, although the order of steps is not limited to this, the second semiconductor layer 50 on which the third wiring layer 60 is laminated is bonded to a separately prepared third semiconductor layer 80 on which a fourth wiring layer 70 is laminated. Then, a light-collecting layer 90 is formed on the light-incident surface side. This almost completes the photodetector 1 shown in FIG. 5N. The photodetector 1 is formed in each of multiple chip formation regions defined by scribe lines (dicing lines) on a semiconductor substrate. The multiple chip formation regions are then individually divided along the scribe lines to form semiconductor chips 2 each equipped with a photodetector 1.

[0068] <<Major Effects of the First Embodiment>> Conventionally, when forming connection pads using the CMP method, as described above, there are cases where the metal constituting the connection pad is polished more than the insulating film. Even in such cases, by overlapping and bonding the wiring layers and then performing a heat treatment, the metal constituting the connection pad can be thermally expanded and the connection pads can be bonded together. However, when attempting to arrange connection pads at a high density, the dimensions and volume of the connection pads become smaller. Furthermore, as the volume of the connection pads becomes smaller, the amount of expansion of the metal constituting the connection pads also decreases.

[0069] On the other hand, to reduce the parasitic capacitance of wiring, the use of low-dielectric-constant insulating materials for the insulating film that constitutes the wiring layer has been considered. However, such low-dielectric-constant insulating materials have lower rigidity than silicon oxide, and depending on the material, their Young's modulus can be as low as one-twentieth that of silicon oxide. When such low-dielectric-constant insulating materials are placed between the bottom surface of the connection pad and the semiconductor layer, they are more easily deformed than materials with higher rigidity. This means that the compressive force generated when the metal that constitutes the connection pad expands may be dissipated by the low-dielectric-constant insulating film located on the opposite side of the connection pad rather than by the connection pad itself. In other words, the low-dielectric-constant insulating material may absorb the compressive force by deforming.

[0070] 4B , in the photodetector 1 according to the first embodiment of the present technology, the insulating film 61 includes a first insulating film 65 made of a first material and a second insulating film 66 made of a material more rigid than the first material and penetrating the first insulating film 65 in the stacking direction, and the first insulating film 65 is provided between the third connection pad 63 and the second semiconductor layer 50. The columnar second insulating film 66 (pillar P) extends along the stacking direction, with one end in the stacking direction contacting the third connection pad 63 and the other end contacting the second semiconductor layer 50. In this way, the pillar P is selectively provided to extend along the stacking direction without interruption from the bottom surface 63 a of the third connection pad 63 to the fourth surface S4 of the second semiconductor layer 50, which has a sufficiently high Young's modulus. This makes it possible to prevent a compressive force generated when the metal constituting the third connection pad 63 and the fourth connection pad 73 expands from escaping to the third wiring layer 60 side. This ensures that when the metal constituting the third connection pad 63 and the fourth connection pad 73 expands, the pressing force acts in the intended direction, causing the connection pads to press against each other, thereby preventing insufficient bonding between the connection pads.

[0071] Furthermore, since a low dielectric constant insulating film can be provided in the wiring layer, an increase in wiring capacitance can be suppressed.

[0072] In the first embodiment, the pillar P is provided in only one wiring layer, but this is not limiting. It is desirable that the pillar P be applied to all of the first wiring layer 30, the second wiring layer 40, the third wiring layer 60, and the fourth wiring layer 70. Furthermore, the pillar P may be applied to any of the above-mentioned wiring layers, or to at least one of them. Furthermore, a plurality of pillars P may be provided for one third connection pad 63.

[0073] FIG. 6 also shows an example in which pillars Pa are provided on the third wiring layer 60 and pillars Pb are provided on the fourth wiring layer 70, which are bonded to each other. In this manner, a pair of connection pads are sandwiched between the pillars Pa and Pb. More specifically, pillars Pa are provided continuously from the surface of the second semiconductor layer 50 to the bottom surface of the third connection pad 63, and pillars Pb are provided continuously from the surface of the third semiconductor layer 80 to the bottom surface of the fourth connection pad 73. This prevents the pressure generated when the metal constituting the third connection pad 63 and the fourth connection pad 73 expands from escaping to the third wiring layer 60 and the fourth wiring layer 70. This causes the connection pads to press against each other more strongly, further preventing insufficient bonding between the connection pads.

[0074] [Modification 1 of the First Embodiment] A first modification of the first embodiment of the present technology shown in Fig. 7 will be described below. The photodetector 1 according to the first modification of the present first embodiment differs from the photodetector 1 according to the first embodiment described above in that a pillar P1 is provided instead of the pillar P, and the configuration of the photodetector 1 other than that is basically the same as that of the photodetector 1 according to the first embodiment described above. Note that components that have already been described are assigned the same reference numerals and descriptions thereof will be omitted.

[0075] Here, an example will be described in which pillars P1 are provided in the third wiring layer 60. The portion of the second insulating film 66 made of the second material that constitutes the pillar P1 (in other words, the second insulating film 66 formed in a pillar shape) penetrates the first insulating film 65 made of the first material in the stacking direction. As in the first embodiment, the pillar P1 extends along the stacking direction, with one end in the stacking direction contacting the third connection pad 63, more specifically contacting the bottom surface 63a of the third connection pad 63, and the other end contacting the second semiconductor layer 50, more specifically contacting the fourth surface S4.

[0076] Furthermore, the pillar P1 is provided at a position where it does not overlap with the wiring 62 formed on the insulating film 61 in the stacking direction, i.e., where it does not overlap with the wiring 62 in a planar view. Therefore, the pillar P1 penetrates the insulating film located between the wirings 62. Furthermore, the pillar P1 is provided with a smaller width than the pillar P shown in FIG. 4A and other figures. This allows the pillar P1 to be provided at a position where it does not overlap with the wiring 62 in a planar view. Furthermore, one or more pillars P1 may be provided for one third connection pad 63. By providing multiple pillars P1 for one third connection pad 63, it is possible to prevent the rigidity between the third connection pad 63 and the second semiconductor layer 50 from becoming insufficient even if the width of the pillar P1 is reduced.

[0077] <Method for manufacturing a photodetector> 8A to 8D, a method for manufacturing the photodetector 1 will be described below. Note that only the step of forming the pillars P1 will be described here.

[0078] First, as shown in FIG. 8A, a portion of the second wiring layer 40 is formed on the fourth surface S4 side of the second semiconductor layer 50. More specifically, wiring 42 belonging to the metal layer M1 is formed, and then a first insulating film 65 is deposited on the exposed surface. In other words, the first insulating film 65 is formed up to the layer immediately before the layer on which the third connection pad 63 is formed. Thereafter, a resist pattern R3 is formed on the exposed surface using known lithography techniques.

[0079] Next, as shown in FIG. 8B, using the resist pattern R3 as a mask, the first insulating film 65 exposed from the openings R3a of the resist pattern R3 is etched using a known etching technique. This etching forms holes 65h. The holes 65h penetrate the first insulating film 65, and their bottom surfaces reach the second semiconductor layer 50. Thereafter, the resist pattern R3 is removed.

[0080] Then, as shown in FIG. 8C, a film 66m made of a second material is deposited so as to fill the holes 65h. Then, as shown in FIG. 8D, excess portions of the film 66m are removed by CMP. More specifically, the exposed surface of the film 66m is polished by CMP to flatten the exposed surface and remove portions of the film 66m other than those embedded in the holes 65h. This forms an insulating film in which different insulating materials are adjacent to each other in a direction perpendicular to the deposition direction. Then, pillars P1 are formed. Thereafter, although not shown, third connection pads 63 are formed by a known method.

[0081] <<Major Effects of Modification 1 of First Embodiment>> The photodetector 1 according to the first modification of the first embodiment also provides the same effects as the photodetector 1 according to the first embodiment described above.

[0082] Furthermore, in the photodetector 1 according to the first modification of the first embodiment, the pillars P1 can be formed by performing photolithography and etching once each, so the number of steps can be reduced compared to the first embodiment.

[0083] Furthermore, in the photodetector 1 according to the first modification of the first embodiment, the pillars P1 are provided to avoid the wiring, so that more of the first material (low dielectric constant insulating material) can be left between the wiring, thereby further suppressing an increase in wiring capacitance.

[0084] Note that both the pillar P1 of this embodiment and the pillar P of the first embodiment may be provided in one photodetector 1. For example, different pillars may be used for different wiring layers, such as providing pillar P in the first wiring layer 30 of the photodetector 1 and providing pillar P1 in the second wiring layer 40. For example, pillar P, which is less subject to restrictions on the placement position of wiring, may be provided in a wiring layer where the gap between wires is insufficient, and pillar P1 may be provided in a wiring layer where it is desired to further reduce the wiring capacitance and where wiring can be avoided.

[0085] [Modification 2 of the First Embodiment] A second modification of the first embodiment of the present technology will be described below. The photodetector 1 according to the second modification of the first embodiment differs from the photodetector 1 according to the first embodiment described above in the second material, but the other configurations of the photodetector 1 are basically the same as those of the photodetector 1 according to the first embodiment described above. Note that components that have already been described are given the same reference numerals, and their description will be omitted. Also, the description will be made with reference to FIGS. 4A and 4B.

[0086] In the first embodiment, the second material was silicon oxide, but in the second modification of the first embodiment, the second material is silicon nitride. Here, the Young's modulus of silicon oxide is 80 GPa, and the Young's modulus of silicon nitride is 200 GPa. In other words, silicon nitride has higher rigidity than silicon oxide. Therefore, the pressure generated when the metal constituting the first connection pad 33 and the second connection pad 43 expands can be more effectively prevented from escaping to the insulating film side. This causes the connection pads to press against each other more, making it possible to more effectively prevent insufficient bonding between the connection pads.

[0087] Furthermore, the linear expansion coefficient of silicon oxide is 0.5 ppm / K, while the linear expansion coefficient of silicon nitride is 2.9 ppm / K. In other words, silicon nitride expands more due to heat than silicon oxide. Therefore, when the pillar P is made of silicon nitride, compared to when it is made of silicon oxide, it is possible to more effectively prevent escape to the insulating film side, and the force pressing the third connection pad 63 toward the fourth connection pad 73 is greater. Therefore, the material with a higher linear expansion coefficient can more effectively prevent deterioration of the contact between the connection pads.

[0088] <<Major Effects of Modification 2 of First Embodiment>> The photodetector 1 according to the second modification of the first embodiment also provides the same effects as the photodetector 1 according to the first embodiment described above.

[0089] Furthermore, since the second material constituting the pillar P of the photodetector 1 according to the second modification of the first embodiment is made of a material with higher rigidity, the pressure generated when the metal constituting the connection pad expands can be more effectively prevented from escaping to the insulating film side.

[0090] Furthermore, the second material constituting the pillars P of the photodetector 1 according to the second modification of the first embodiment is made of a material with a larger linear expansion coefficient, so that the force pressing one connection pad toward the other connection pad is larger. Therefore, the material with a larger linear expansion coefficient can more effectively prevent the contact between the connection pads from deteriorating.

[0091] Although the second material constituting the pillars P of the photodetector 1 according to the second modification of the first embodiment described above is silicon nitride, this is not limiting. For example, the pillars P may include both a portion (or layer) made of silicon nitride and a portion (or layer) made of silicon oxide. In this way, the pillars P may include portions (or layers) made of different materials as long as the materials satisfy the conditions for the second material.

[0092] Furthermore, in the second modification of the first embodiment, an example in which the pillar P shown in FIG. 4A etc. is made of silicon nitride has been described, but this is not limiting, and the pillar P1 shown in FIG. 7 etc. may also be made of silicon nitride. Furthermore, the pillar P1 may include both a portion (or layer) made of silicon nitride and a portion (or layer) made of silicon oxide. The pillar P1 may also include a portion (or layer) made of a different material as long as the material satisfies the conditions for the second material. Even in this case, the same effects as those of the photodetector 1 according to the second modification of the first embodiment can be obtained.

[0093] [Second embodiment] A second embodiment of the present technology shown in Figures 9 and 10 will be described below. The photodetector 1 according to this second embodiment differs from the photodetector 1 according to the first embodiment described above in the configuration of the connection pads, but the other configurations of the photodetector 1 are basically the same as those of the photodetector 1 according to the first embodiment described above. Note that components that have already been described are assigned the same reference numerals and descriptions thereof will be omitted.

[0094] <Insulating film> 9, the first wiring layer 30 has an insulating film 31A, the second wiring layer 40 has an insulating film 41A, the third wiring layer 60 has an insulating film 61A, and the fourth wiring layer 70 has an insulating film 71A. The insulating films 31A, 41A, 61A, and 71A include, for example, a layer made of silicon oxide, although they are not limited thereto.

[0095] <Connection pad> FIG. 10 is an explanatory diagram illustrating the configuration of a connection pad. The connection pad shown in FIG. 10 is referred to as connection pad A for convenience. The configuration of connection pad A can be applied to any of the first connection pad 33, second connection pad 43, third connection pad 63, and fourth connection pad 73 shown in FIG. 9. It is desirable to apply the configuration of connection pad A to all of the first connection pad 33, second connection pad 43, third connection pad 63, and fourth connection pad 73, but it may also be applied to at least one of these connection pads.

[0096] 10, the connection pad A includes a first portion a, a second portion b, and a seed layer c. The connection pad A is provided in an opening e provided in an insulating film d. A barrier metal layer f is provided between the connection pad A and the insulating film d.

[0097] The first portion a is made of a first metal and forms the surface of the connection pad A. When the connection pad A is heat-treated, the first portion a thermally expands. More specifically, before the heat treatment, the first portion a occupies an area within the opening e from a position near the bottom e1 of the opening e to the height of the dashed line, as shown in FIG. 10, although this is not limited thereto. When the connection pad A is heat-treated, the first portion a thermally expands from the height of the dashed line in the direction indicated by the arrow a1, and protrudes from the surface d1 of the insulating film d. The first metal may be made of, but is not limited to, copper (Cu), for example. Here, the description will be given assuming that the first metal is copper.

[0098] The second portion b is provided between the first portion a and the insulating film d. The second portion b is made of a second metal that is more susceptible to plastic deformation than the first metal. In other words, the second metal has lower rigidity than the first metal. A metal that is susceptible to plastic deformation is a metal that is easily deformed when subjected to force and has low yield stress or resistance. Metals have the property of becoming permanently deformed when a force greater than a certain level is applied. Yield stress represents the force at which a material begins to become plastic. For metals with unclear yield stress, the resistance to plastic deformation is sometimes evaluated as the resistance. Furthermore, the more easily a metal is plastically deformed, the smaller the force required to deform it.

[0099] When the connection pad A is heat-treated, the second portion b undergoes plastic deformation. More specifically, when the connection pad A is heat-treated, of the sidewall portion b1 and bottom portion b2 of the second portion b, mainly the sidewall portion b1 undergoes plastic deformation. In other words, the second portion b needs to be provided at least between the side surface of the first portion a and the insulating film d. Here, the bottom portion b2 is the portion located closer to the bottom e1 of the opening e, and the sidewall portion b1 is the portion located closer to the sidewall e2 of the opening e.

[0100] Before heat treatment, although not limited thereto, assume that sidewall portion b1 occupies an area within opening e from the bottom e1 side of opening e to the height of the dashed line, as shown in FIG. 10. Then, when heat treatment is performed on connection pad A, sidewall portion b1 is pulled by the thermal expansion of first portion a from the height of the dashed line and expands together with first portion a while undergoing plastic deformation in the direction indicated by arrow b3. Furthermore, second portion b may thermally expand at the same time as undergoing plastic deformation. Sidewall portion b1 may thermally expand in the direction indicated by arrow b3 at the same time as undergoing plastic deformation.

[0101] When heat treatment is performed on connection pad A, the surface b11 of side wall b1 near barrier metal layer f is constrained by barrier metal layer f. This is because the amount of deformation of barrier metal layer f due to heat is small. In contrast, the surface b12 of side wall b1 near first portion a is subjected to tension due to thermal expansion of first portion a. As a result of different forces acting on surfaces b11 and b12 in this way, side wall b1 undergoes plastic deformation.

[0102] Examples of the second metal include aluminum (Al), aluminum-copper alloy (AlCu), and aluminum-silicon alloy (AlSi). These metals are prone to plastic deformation at room temperature. Furthermore, since the first metal expands when heat-treated, the second metal may be more prone to plastic deformation than the first metal when heated. More specifically, even if a metal is difficult to plastically deform at room temperature, it can be used as the second metal as long as it is more prone to plastic deformation than the first metal at the temperature at which the connection pad is heat-treated.

[0103] Metals that are more susceptible to plastic deformation than the first metal when heated include, for example, metals with low melting points. Examples of metals with low melting points include cadmium (Cd), tin (Sn), tantalum (Tl), and lead (Pb). The melting points of these metals are lower than 400°C.

[0104] Generally, when a metal is heated toward its melting point, its rigidity decreases. Therefore, a metal that is less rigid than the first metal at the temperature at which the connection pad is heat-treated can be considered to be more susceptible to plastic deformation than the first metal when heated, even if it has a higher melting point. Examples of such metals include antimony (Sb), ytterbium (Yb), calcium (Ca), silver (Ag), germanium (Ge), strontium (Sr), cerium (Ce), and lead-copper alloys (PbCu). The melting points of these metals are lower than 1000°C. The melting point of aluminum (Al) is also lower than 1000°C. In this embodiment, the second metal is described as an aluminum-copper alloy.

[0105] The seed layer c serves as an electrode when depositing metal using electroplating. The seed layer c also serves as a seed layer for the metal deposited by electroplating. The material constituting the seed layer c can be selected depending on the type of metal to be deposited on the seed layer c. More specifically, since the second portion b is deposited on the exposed surface of the seed layer c, the seed layer c can be made of a material that can serve as a seed for the material constituting the second portion b.

[0106] In this embodiment, since the second metal is an aluminum-copper alloy, the material constituting the seed layer c is composed of a material that can serve as a seed for the aluminum-copper alloy. For example, the seed layer c may be composed of a metal such as an aluminum-copper alloy or copper. Here, an example in which the seed layer c is composed of an aluminum-copper alloy will be described.

[0107] The barrier metal layer f includes, but is not limited to, a high-melting-point metal. The barrier metal layer f is made of a metal such as titanium (Ti), titanium nitride (TiN), or tantalum (Ta). The barrier metal layer f has the function of adhering the connection pad A to the insulating film d and the function of preventing the metal constituting the connection pad A from diffusing into the insulating film d.

[0108] <Method for manufacturing a photodetector> 11A to 11F, a method for manufacturing the photodetector 1 will be described. Note that only a method for forming the connection pads will be described here. As an example of a method for forming the connection pads, a method for forming the fourth connection pad 73 will be described.

[0109] As shown in FIG. 11A, layers up to the metal layer M4 are formed on the fifth surface S5 side of the third semiconductor layer 80. Then, an insulating film 71Am is laminated on the exposed surface of the wiring layer. The insulating film 71Am is not limited to this, but may have a layered structure in which, for example, a silicon oxide film, a silicon nitride film, and a silicon oxide film are laminated in that order. Then, as shown in FIG. 11B, an opening e is formed in the insulating film 71Am using known lithography and etching techniques. Note that from the following figures onwards, the insulating film 71Am and the insulating film 71A will not be distinguished from each other and will be simply referred to as the insulating film 71A.

[0110] 11C, a film fm constituting the barrier metal layer f and a film cm constituting the seed layer c are laminated in that order on the exposed surface of the insulating film 71A using a known technique such as sputtering, and then metal is deposited by plating.

[0111] First, as shown in FIG. 11D, in the initial stage of plating, a film bm made of a second metal is deposited on the exposed surface of the film cm. Here, an aluminum-copper alloy is deposited as the second metal. Then, as shown in FIG. 11E, a film am made of a first metal is deposited on the exposed surface of the film bm by plating. Here, copper is deposited.

[0112] 11F, excess portions of the films fm, cm, bm, and am are removed by CMP. More specifically, the exposed surfaces of the wiring layers are polished by CMP to planarize the exposed surfaces and remove the films fm, cm, bm, and am other than the portions embedded in the openings e. This nearly completes the formation of the fourth connection pad 73 belonging to the metal layer M5. The third wiring layer 60 and the fourth wiring layer 70 are then superimposed and bonded, and heat treated.

[0113] 11F, the fourth connection pad 73 has a body 73a and a head 73b, which is wider than the body 73a and is connected to the end of the body 73a opposite the third semiconductor layer 80 side along the stacking direction from the third semiconductor layer 80 side. Of the body 73a and the head 73b, the head 73b, which has a larger volume than the body 73a, expands more during heat treatment. Furthermore, the head 73b constitutes the surface of the fourth connection pad 73, and the portion that is desired to expand more during heat treatment is primarily the portion that constitutes the head 73b in order to prevent deterioration of contact between the connection pads. Therefore, the sidewall b1 of the second portion b only needs to be formed on at least the sidewall of the head 73b out of the sidewall of the body 73a and the sidewall of the head 73b.

[0114] Note that the configuration of the connection pad A may be applied to the third connection pad 63 bonded to the fourth connection pad 73 as described above, if necessary. For example, as long as bonding between the third connection pad 63 and the fourth connection pad 73 can be obtained, the configuration of the connection pad A may not be applied to the third connection pad 63. Furthermore, in some cases, it may be desirable to apply the configuration of the connection pad A to the third connection pad 63 in order to obtain bonding between the third connection pad 63 and the fourth connection pad 73.

[0115] <<Major Effects of the Second Embodiment>> Conventionally, heat treatment is performed after bonding connection pads together to expand the metal constituting the connection pads and prevent deterioration of the contact between the connection pads. Furthermore, when forming connection pads using the CMP method, the metal constituting the connection pads may be ground back more than the insulating film, resulting in a recess. When a recess occurs, it is necessary to expand the metal constituting the connection pads by heat treatment, and use the expansion to compensate for the volume of the recess in order to prevent deterioration of the contact between the connection pads.

[0116] On the other hand, with the miniaturization of elements, it is desirable to reduce the dimensions of connection pads. Reducing the dimensions of connection pads also reduces their volume. As the volume of connection pads decreases, the amount of expansion during heat treatment also decreases. The amount of expansion of metals due to heat is determined by the volume and coefficient of expansion of the metal. The coefficient of expansion is constant, but as the volume decreases, the amount of expansion decreases.

[0117] In addition, the barrier metal layer between the connection pad and the insulating film is less likely to deform due to heat. Therefore, even if the metal constituting the connection pad attempts to expand during heat treatment, the surface of the metal constituting the connection pad that comes into contact with the barrier metal layer is constrained by the barrier metal layer, which can sometimes suppress the expansion of the metal constituting the connection pad. The constraint from the barrier metal layer has a greater effect on the amount of expansion as the dimensions of the connection pad become smaller.

[0118] When heat treatment is performed, the central portion of a connection pad is generally more likely to expand in plan view. This is because the central portion is farther from the barrier metal layer than the peripheral portion and is less subject to constraint. If the dimensions of the connection pad in plan view are reduced, the distance between the central portion of the connection pad in plan view and the barrier metal layer also decreases. Therefore, the smaller the dimensions of the connection pad in plan view, the more likely the central portion is to be constrained by the barrier metal layer. As a result, the intended amount of expansion may not be achieved due to the obstruction caused by the barrier metal layer. Therefore, to ensure the desired amount of expansion, the dimensions of the connection pad are sometimes increased in the stacking direction. However, increasing the size of the connection pad in the stacking direction increases the volume of the connection pad, which in turn increases the dimensions of the semiconductor chip in the stacking direction.

[0119] In contrast, in a photodetector 1 according to a second embodiment of the present disclosure, at least one of a pair of connection pads includes a first portion a made of a first metal and constituting the surface of the connection pad, and a second portion b provided between the first portion a and the insulating film and made of a second metal that is more susceptible to plastic deformation than the first metal. As a result, even if the surface b11 of the second portion b is constrained by the barrier metal layer f during heat treatment, the second metal constituting the second portion b undergoes plastic deformation, thereby absorbing the constraint from the barrier metal layer f. Therefore, the constraint from the barrier metal layer f is less likely to be transmitted to the first portion a, and the expansion of the first portion a can be prevented from being affected by the barrier metal layer f. As a result, even if the dimensions of the connection pads in a plan view are reduced, deterioration of the contact between the connection pads can be prevented.

[0120] A simulation of the thermal expansion of the metal that makes up the connection pad showed that the amount of thermal expansion was improved by approximately 33 percent when the second part b made of the second metal was included compared to when it was not included.

[0121] Furthermore, in the photodetector 1 according to the second embodiment of the present technology, the barrier metal layer can be prevented from inhibiting the expansion of the metal constituting the connection pads, thereby preventing deterioration of the contact between the connection pads even if they have the same capacitance. Therefore, it is not necessary to increase the dimension of the connection pads in the stacking direction in order to increase their capacitance. This prevents an increase in the thickness of the semiconductor chip 2 in the stacking direction.

[0122] Furthermore, the photodetector 1 according to the second embodiment also provides the same effects as the photodetector 1 according to the first embodiment described above.

[0123] [Modification 1 of the second embodiment] A first modification of the second embodiment of the present technology shown in Fig. 12 will be described below. The photodetector 1 according to the first modification of the present second embodiment differs from the photodetector 1 according to the second embodiment described above in that the seed layer c is made of a second metal, and the other configuration of the photodetector 1 is basically the same as that of the photodetector 1 according to the second embodiment described above. Note that components that have already been described are assigned the same reference numerals and their description will be omitted.

[0124] <Connection pad> FIG. 12 is an explanatory diagram illustrating the configuration of a connection pad. The connection pad shown in FIG. 12 is referred to as connection pad A1 for convenience. The configuration of connection pad A1 can be applied to any of the first connection pad 33, second connection pad 43, third connection pad 63, and fourth connection pad 73 shown in FIG. 9. It is desirable to apply the configuration of connection pad A1 to all of the first connection pad 33, second connection pad 43, third connection pad 63, and fourth connection pad 73, but it may also be applied to at least one of these connection pads.

[0125] The connection pad A includes a first portion a and a seed layer c that functions as a base for stacking the first portion a (first metal). In the first modification of the second embodiment, the seed layer c functions as the second portion. It functions as a seed layer. The seed layer c is provided between the first portion a and the insulating film d. The seed layer c is made of a second metal that is more susceptible to plastic deformation than the first metal. The first portion a is deposited on the seed layer c by a plating method. Therefore, it is desirable that the seed layer c be made of a metal, among the above-mentioned second metals, that also serves as a seed layer for the first metal that constitutes the first portion a.

[0126] <<Major Effects of Modification 1 of Second Embodiment>> The photodetector 1 according to the first modification of the second embodiment also provides the same effects as the photodetector 1 according to the second embodiment described above.

[0127] [Modification 2 of the Second Embodiment] Modification 2 of the second embodiment of the present technology shown in Fig. 13 will be described below. The photodetector 1 according to Modification 2 of the present second embodiment differs from the photodetector 1 according to the second embodiment described above in that the barrier metal layer f is made of a second metal, and other than that, the configuration of the photodetector 1 is basically the same as that of the photodetector 1 according to the second embodiment described above. Note that components that have already been described are assigned the same reference numerals and their description will be omitted.

[0128] <Connection pad> FIG. 13 is an explanatory diagram illustrating the configuration of a connection pad. The connection pad shown in FIG. 13 is referred to as connection pad A2 for convenience. The configuration of connection pad A2 can be applied to any of the first connection pad 33, second connection pad 43, third connection pad 63, and fourth connection pad 73 shown in FIG. 9. It is desirable to apply the configuration of connection pad A2 to all of the first connection pad 33, second connection pad 43, third connection pad 63, and fourth connection pad 73, but it may also be applied to at least one of these connection pads.

[0129] The connection pad A includes a first portion a and a barrier metal layer f. In the second modification of the second embodiment, the barrier metal layer f is also included in the connection pad A. The barrier metal layer f functions as the second portion. The barrier metal layer f is provided between the first portion a and the insulating film d. The barrier metal layer f is made of a second metal that is more susceptible to plastic deformation than the first metal. The barrier metal layer f also has the function of adhering the first portion a to the insulating film d and the function of suppressing the diffusion of the metal constituting the first portion a into the insulating film d. Therefore, it is desirable that the barrier metal layer f be made of a metal from the second metal that has the above-mentioned function.

[0130] <<Major Effects of Modification 2 of Second Embodiment>> The photodetector 1 according to the second modification of the second embodiment also provides the same effects as the photodetector 1 according to the second embodiment described above.

[0131] [Third embodiment] A third embodiment of the present technology shown in Figures 14 and 15 will be described below. The photodetector 1 according to this third embodiment differs from the photodetector 1 according to the first embodiment described above in terms of the insulating film of the wiring layer, but the other configuration of the photodetector 1 is basically the same as that of the photodetector 1 according to the first embodiment described above. Note that components that have already been described are assigned the same reference numerals, and descriptions thereof will be omitted.

[0132] <Insulating film> 14, the first wiring layer 30 has an insulating film 31B, the second wiring layer 40 has an insulating film 41B, the third wiring layer 60 has an insulating film 61B, and the fourth wiring layer 70 has an insulating film 71B. The insulating film 31B includes insulating films da31 and db31, the insulating film 41B includes insulating films da41 and db41, the insulating film 61B includes insulating films da61 and db61, and the insulating film 71B includes insulating films da71 and db71. When it is not necessary to distinguish between the insulating films da31, da41, da61, and da71, they will not be distinguished from each other and will simply be referred to as the insulating film da. When it is not necessary to distinguish between the insulating films db31, db41, db61, and db71, they will not be distinguished from each other and will simply be referred to as the insulating film db.

[0133] <Part 3 and Part 4> 15 is an explanatory diagram illustrating the configuration of the insulating film around the connection pads. As shown in FIG. 15, the wiring layer C1 is superimposed on and bonded to the wiring layer C2. The wiring layer C1 and the wiring layer C2 each include an insulating film d and a connection pad B provided on the insulating film d, and are electrically coupled to each other by bonding the surfaces of the connection pads B together. The connection pads B are not limited to this, but may have a configuration similar to that of the connection pads of the first embodiment, for example.

[0134] The insulating film d includes a laminated structure of insulating films da and db. The insulating films da and db are laminated in that order. The connection pad B is provided in an opening e in the insulating film d. The portion of the insulating film d adjacent to the side surface B1 of the connection pad B is called the third portion to distinguish it from the other portions, and the portion adjacent to the bottom surface B2 of the connection pad B is called the fourth portion to distinguish it from the other portions. The linear expansion coefficient of the material constituting the third portion is smaller than the linear expansion coefficient of the material constituting the fourth portion. In the example shown in FIG. 15, of the insulating films da and db, the insulating film db is the third portion, and the insulating film da is the fourth portion. While it is desirable to apply the configurations of the third and fourth portions to all of the insulating films 31B, 41B, 61B, and 71B as shown in FIG. 14, they may also be applied to any of the connection pads. The configurations of the third and fourth portions may also be applied to at least one of these connection pads.

[0135] When bonding the wiring layer C1 and the wiring layer C2, the wiring layer C1 and the wiring layer C2 are first overlapped, and then heat treatment is performed. The connection pads B expand when heat treatment is performed, and the surfaces of the connection pads B are bonded together. Arrow B3 schematically indicates the amount of expansion of the connection pads B due to heat treatment. The amount of expansion of the connection pads B indicated by arrow B3 is preferably greater. Note that dashed line B4 in Figure 15 indicates the position of the surface of the connection pads B before heat treatment. Furthermore, when the wiring layer C1 and the wiring layer C2 are heat treated, the insulating film d also expands. Arrow db1 schematically indicates the amount of expansion of the insulating film db due to heat treatment.

[0136] The greater the expansion amount of the connection pads B, the more the contact between the connection pads can be prevented from deteriorating. Furthermore, the smaller the expansion amount of the insulating film db, the more the contact between the connection pads can be prevented from deteriorating. This is because the expansion amount of the connection pads B is essentially the same as the amount of shrinkage due to the expansion amount of the insulating film db. Therefore, it is desirable to increase the difference (linear expansion coefficient difference) between the linear expansion coefficient of the material constituting the connection pads B and the linear expansion coefficient of the material constituting the insulating film db. In this embodiment, the material constituting the insulating film db is devised to increase this difference in linear expansion coefficient. It is preferable to use a material with a smaller linear expansion coefficient as the material constituting the insulating film db.

[0137] The material constituting the insulating film da is stacked on top of the connection pad B in the stacking direction, so the linear expansion coefficient of the material does not substantially reduce the expansion of the connection pad B. Therefore, of the insulating film da and the insulating film db, the insulating film db is made of a material with a smaller linear expansion coefficient.

[0138] The material constituting the insulating film db may be, for example, a glass ceramic whose linear expansion coefficient is adjusted by an additive. The additive is, but is not limited to, a material that shrinks when the temperature rises. In this description, the material constituting the insulating film db is assumed to be such a glass ceramic. The insulating film da may include, for example, a layer made of silicon oxide.

[0139] <Method for manufacturing a photodetector> 16A to 16F, a method for manufacturing the photodetector 1 will be described. Note that only a method for forming the connection pads will be described here. As an example of a method for forming the connection pads, a method for forming the second connection pads 43 will be described.

[0140] As shown in FIG. 16A, layers up to the metal layer M4 are formed on the third surface S3 side of the second semiconductor layer 50w. The portion of the insulating film da41 that is exposed on the exposed surface of the wiring layer is made of, for example, a silicon oxide film. Then, glass ceramic db41 is laminated on the exposed surface of the wiring layer. More specifically, a plate-shaped glass ceramic db41 having the same size as the second semiconductor layer 50w is prepared, and the prepared glass ceramic db41 is bonded to the exposed surface of the wiring layer. Then, as shown in FIG. 16B, the exposed surface of the glass ceramic db41 is subjected to backgrinding or the like to reduce its thickness.

[0141] Next, as shown in FIG. 16C, the glass ceramic db41 is etched using known lithography and etching techniques to form an opening e. The resist pattern is then removed. Then, as shown in FIG. 16D, a copper film 43m is deposited on the exposed surface of the wiring layer to fill the opening e. More specifically, copper is first deposited using a known technique such as sputtering, and then copper is deposited by plating. Then, as shown in FIG. 16E, excess portions of the film 43m are removed by CMP to obtain second connection pads 43. Then, as shown in FIG. 16F, the second wiring layer 40 is superimposed on the first wiring layer 30 and heat-treated. In the example shown in FIG. 16F, the insulating film 31 of the first wiring layer 30 also contains the glass ceramic db31, just like the second wiring layer 40.

[0142] <<Major Effects of the Third Embodiment>> Consider the case where silicon oxide, a commonly used material for the insulating film db, is used. The linear expansion coefficient of copper is 16.5 ppm / K, while that of silicon oxide is 0.6 ppm / K, resulting in a difference of 15.9 ppm / K between the two. As the dimensions of connection pads shrink with the miniaturization of elements, the amount of expansion of the metal that makes up the connection pads becomes important in order to compensate for the recess that occurs when the metal recedes.

[0143] Consider the case where ZERODUR (registered trademark) manufactured by SCHOTT is used as the material for the insulating film db (third portion). ZERODUR (registered trademark) is a glass ceramic with a linear expansion coefficient of 0.02 ppm / K. Therefore, the difference in linear expansion coefficient from copper is 16.48 ppm / K. In this way, the linear expansion coefficient can be made larger than when the insulating film db is made of silicon oxide.

[0144] In this way, in the photodetector 1 according to the third embodiment of the present technology, by using a material with a smaller linear expansion coefficient as the material for the insulating film db, it is possible to prevent the expansion of the connection pads from being substantially reduced by the expansion of the insulating film db, thereby preventing insufficient bonding between the connection pads.

[0145] Furthermore, in the photodetector 1 according to the third embodiment of the present technology, the linear expansion coefficient of the material constituting the third portion, which is the portion adjacent to the side surface of the connection pad, is smaller than the linear expansion coefficient of the material constituting the fourth portion, which is the portion adjacent to the bottom surface of the connection pad. Of the insulating films da and db, the insulating film db, which affects the substantial expansion amount of the connection pad, is selectively made of a material with a smaller linear expansion coefficient, thereby preventing insufficient bonding between the connection pads.

[0146] Furthermore, the photodetector 1 according to the third embodiment also provides the same effects as the photodetector 1 according to the first embodiment described above.

[0147] [Modification 1 of the third embodiment] Modification 1 of the third embodiment of the present technology shown in Fig. 17 will be described below. The photodetector 1 according to Modification 1 of the third embodiment differs from the photodetector 1 according to the third embodiment described above in that a contact layer is provided, but the other configuration of the photodetector 1 is basically the same as that of the photodetector 1 according to the third embodiment described above. Note that components that have already been described are assigned the same reference numerals and descriptions thereof will be omitted.

[0148] <Contact layer> 17 is an explanatory diagram illustrating the configuration of the contact layer g. The contact layer g is provided between the insulating film db and the insulating film da, which are the third portion. More specifically, the insulating film db and the insulating film da, which are the third portion, are bonded via the contact layer g. In addition, a contact layer g is provided between the insulating film db and the connection pad B. The contact layer g includes at least one layer of a silicon oxide film, a silicon nitride film, a silicon carbonitride (SiCN) film, a carbon-containing silicon oxide film, a silicon carbide (SiC) film, an aluminum oxide film (Al2O3), and a tantalum oxide film (Ta2O3).

[0149] <Method for manufacturing a photodetector> 18A to 18G, a method for manufacturing the photodetector 1 will be described. Note that only a method for forming the connection pads will be described here. As an example of a method for forming the connection pads, a method for forming the second connection pads 43 will be described.

[0150] As shown in FIG. 18A, layers up to the metal layer M4 are formed on the third surface S3 side of the second semiconductor layer 50w. The portion of the insulating film da41 that is exposed on the exposed surface of the wiring layer is made of, for example, a silicon oxide film. Then, a glass ceramic db41 having contact layers g on both sides is laminated on the exposed surface of the wiring layer (e.g., insulating film da41, etc.). More specifically, a plate-shaped glass ceramic db41 having the same size as the second semiconductor layer 50w and contact layers g deposited on both sides is prepared, and the prepared glass ceramic db41 is bonded to the exposed surface of the wiring layer. Then, as shown in FIG. 18B, the exposed surface is subjected to backgrinding or the like to reduce the thickness of the glass ceramic db41.

[0151] Next, as shown in FIG. 18C, the glass ceramic db41 and the contact layer g are etched using known lithography and etching techniques to form an opening e. The resist pattern is then removed. Then, as shown in FIG. 18D, a contact layer g is deposited on the exposed surface. Next, as shown in FIG. 18E, the contact layer g deposited on the bottom surface of the opening e is removed using known lithography and etching techniques. This leaves the portion of the contact layer g deposited on the exposed surface of the glass ceramic db41. More specifically, the portion deposited on the side of the opening e and the portion deposited on the surface of the glass ceramic db41 opposite the second semiconductor layer 50 are left. The resist pattern is then removed.

[0152] Next, as shown in FIG. 18F, a copper film is deposited on the exposed surface of the wiring layer so as to fill the opening e. Then, excess copper film is removed by CMP, thereby obtaining second connection pad 43. This CMP process also removes the portion of contact layer g that is stacked on the surface of glass ceramic db41 opposite to the second semiconductor layer 50, thereby exposing glass ceramic db41.

[0153] 18G, the second wiring layer 40 is superimposed on the first wiring layer 30 and heat treated. In the example shown in FIG. 18G, the insulating film 31 of the first wiring layer 30 also has the glass ceramic db41 and the contact layer g, similar to the second wiring layer 40. Then, the exposed surfaces of the glass ceramic db41 are bonded together, and the first connection pad 33 and the second connection pad 43 are bonded together.

[0154] <<Major Effects of Modification 1 of Third Embodiment>> The photodetector 1 according to the first modification of the third embodiment also provides the same effects as the photodetector 1 according to the third embodiment described above.

[0155] Furthermore, in the photodetector 1 according to the first modified example of the third embodiment, a contact layer g is laminated on the portion of the glass ceramic db that is joined to the wiring layer, so that the bonding strength between the layers that make up the wiring layer can be at least the same as that of the conventional device.

[0156] Furthermore, contact layers g are provided between the glass ceramic db and the insulating film da, and between the glass ceramic db and wiring such as the second connection pad 43, thereby preventing the material that constitutes the glass ceramic db from diffusing into the surrounding area.

[0157] In the first variant of the third embodiment, the contact layer g is deposited on both sides of the glass ceramic db41, but it may be deposited only on the surface of the glass ceramic db41 that is bonded to the wiring layer.

[0158] [Modification 2 of the third embodiment] A second modification of the third embodiment of the present technology will be described below. The photodetector 1 according to the second modification of the third embodiment differs from the photodetector 1 according to the third embodiment described above in that the material constituting the third portion (insulating film db) is different; otherwise, the configuration of the photodetector 1 is basically the same as that of the photodetector 1 according to the third embodiment described above. Note that components that have already been described are given the same reference numerals, and their description will be omitted. Also, the description will be given here using FIGS. 14 and 15.

[0159] <3rd part> The linear expansion coefficient of the material constituting the third portion (insulating film db) is smaller than the linear expansion coefficient of the material constituting the fourth portion (insulating film da). More specifically, the linear expansion coefficient of the material constituting the insulating film db is a negative value. Generally, substances expand when heated, but materials with a negative linear expansion coefficient have the property of contracting when heated. The insulating film db is made of or contains a material with a negative linear expansion coefficient. Examples of materials with a negative linear expansion coefficient include cubic zirconium tungstate, copper (Cu)-zinc (Zn)-vanadium (V) oxide (Cu-Zn-VO-based oxide), zirconium phosphate, zirconium tungstate phosphate, and fillers made of glass with a negative linear expansion coefficient.

[0160] Cubic zirconium tungstate contracts continuously with increasing temperature from 0.3 K to its thermal decomposition temperature of 1050 K. Materials exhibiting similar behavior include compounds with the formula AM2O8 (A = zirconium (Zr) or hafnium (Hf), M = molybdenum (Mo) or tungsten (W)) and zirconium pyrovanadate (ZrVO7). Compounds with the formula A2(MO4)3 (A = zirconium (Zr) or hafnium (Hf), M = molybdenum (Mo) or tungsten (W)) also exhibit controllable negative thermal expansion.

[0161] Cu-Zn-VO oxides are oxides made of three metals: copper, zinc, and vanadium. An example of a Cu-Zn-VO oxide is CG-NiTE (registered trademark) manufactured by IBLC Corporation. The linear expansion coefficient of CG-NiTE (registered trademark) is approximately -10 ppm / K to -5 ppm / K. Cu-Zn-VO oxides may be in the form of particles, which may be added to materials such as glass and resin before use.

[0162] The linear expansion coefficient of zirconium phosphate is about -2, and the linear expansion coefficient of zirconium tungstate phosphate is about -3.

[0163] An example of a filler made of glass having a negative linear expansion coefficient is a filler made of low thermal expansion crystallized glass manufactured by Nippon Electric Glass Co., Ltd. The linear expansion coefficient of a filler made of low thermal expansion crystallized glass manufactured by Nippon Electric Glass Co., Ltd. is, for example, about -1.1 ppm / K to -0.9 ppm / K. Because the filler is in particulate form, it may be used in a state where it is added to a material such as glass or resin.

[0164] <<Major Effects of Modification 2 of Third Embodiment>> The photodetector 1 according to the second modification of the third embodiment also provides the same effects as the photodetector 1 according to the third embodiment described above.

[0165] Consider a case where zirconium phosphate is used as the material for the insulating film db (third portion) in the photodetector 1 according to Modification 2 of the third embodiment. The linear expansion coefficient of zirconium phosphate is −2 ppm / K. Therefore, the difference in linear expansion coefficient between zirconium phosphate and copper, which has a linear expansion coefficient of 16.5 ppm / K, is 18.5 ppm / K. In this way, the linear expansion coefficient can be made larger than when the insulating film db described in the third embodiment is made of silicon oxide. Furthermore, because zirconium phosphate has a negative linear expansion coefficient, the difference in linear expansion coefficient can be made larger than the linear expansion coefficient of copper, which is 16.5 ppm / K. Therefore, the effective linear expansion coefficient of the metal constituting the connection pad, such as copper, can be made larger than the original value of that material. In other words, the effective linear expansion coefficient can be increased without changing the metal constituting the connection pad. This prevents insufficient bonding between the connection pads.

[0166] The material having the negative linear expansion coefficient described above may be used as a material constituting the insulating film db (third portion) in the photodetector 1 according to the first modification of the third embodiment shown in FIG. 17, etc.

[0167] [Fourth embodiment] <1. Application examples to electronic devices> Next, an electronic device 100 according to a fourth embodiment of the present technology shown in Fig. 19 will be described. The electronic device 100 includes a solid-state imaging device 101, an optical lens 102, a shutter device 103, a drive circuit 104, and a signal processing circuit 105. The electronic device 100 is, for example, an electronic device such as a camera, but is not limited thereto. The electronic device 100 also includes the above-described photodetector 1 as the solid-state imaging device 101.

[0168] An optical lens (optical system) 102 focuses image light (incident light 106) from a subject onto the imaging surface of the solid-state imaging device 101. This causes signal charges to accumulate in the solid-state imaging device 101 for a certain period of time. A shutter device 103 controls the light irradiation period and light blocking period of the solid-state imaging device 101. A drive circuit 104 supplies drive signals that control the transfer operation of the solid-state imaging device 101 and the shutter operation of the shutter device 103. Signal transfer from the solid-state imaging device 101 is performed based on the drive signals (timing signals) supplied from the drive circuit 104. A signal processing circuit 105 performs various signal processing on signals (pixel signals) output from the solid-state imaging device 101. The processed video signals are stored in a storage medium such as a memory or output to a monitor.

[0169] With this configuration, the electronic device 100 includes the photodetector 1, which has reduced power consumption and increased speed as the solid-state imaging device 101, and therefore can reduce power consumption and further increase speed of the electronic device 100. Furthermore, it is possible to prevent insufficient bonding between the connection pads of the solid-state imaging device 101, thereby improving the reliability of the electronic device 100.

[0170] The electronic device 100 is not limited to a camera, but may be other electronic devices, such as an imaging device such as a camera module for a mobile device such as a mobile phone.

[0171] Furthermore, the electronic device 100 can be provided with, as the solid-state imaging device 101, a photodetector 1 according to any one of the first to third embodiments and their modifications, or a photodetector 1 according to a combination of at least two of the first to third embodiments and their modifications.

[0172] <2. Application examples for mobile devices> The technology according to the present disclosure (the present technology) can be applied to various products. For example, the technology according to the present disclosure may be realized as a device mounted on any type of moving body, such as an automobile, an electric vehicle, a hybrid electric vehicle, a motorcycle, a bicycle, personal mobility, an airplane, a drone, a ship, or a robot.

[0173] FIG. 20 is a block diagram showing a schematic configuration example of a vehicle control system, which is an example of a mobile object control system to which the technology according to the present disclosure can be applied.

[0174] The vehicle control system 12000 includes a plurality of electronic control units connected via a communication network 12001. In the example shown in Fig. 20, the vehicle control system 12000 includes a drive system control unit 12010, a body system control unit 12020, an outside-vehicle information detection unit 12030, an inside-vehicle information detection unit 12040, and an integrated control unit 12050. Also shown as functional components of the integrated control unit 12050 are a microcomputer 12051, an audio / video output unit 12052, and an in-vehicle network I / F (interface) 12053.

[0175] The drivetrain control unit 12010 controls the operation of devices related to the drivetrain of the vehicle in accordance with various programs. For example, the drivetrain control unit 12010 functions as a control device for a drive force generating device for generating a drive force of the vehicle, such as an internal combustion engine or a drive motor, a drive force transmission mechanism for transmitting the drive force to the wheels, a steering mechanism for adjusting the steering angle of the vehicle, a braking device for generating a braking force of the vehicle, etc.

[0176] The body system control unit 12020 controls the operation of various devices equipped in the vehicle body according to various programs. For example, the body system control unit 12020 functions as a control device for a keyless entry system, a smart key system, a power window device, or various lamps such as headlamps, backup lamps, brake lamps, turn signals, and fog lamps. In this case, radio waves transmitted from a portable device that serves as a key or signals from various switches may be input to the body system control unit 12020. The body system control unit 12020 receives these radio waves or signals and controls the vehicle's door lock device, power window device, lamps, etc.

[0177] The outside-vehicle information detection unit 12030 detects information outside the vehicle equipped with the vehicle control system 12000. For example, an imaging unit 12031 is connected to the outside-vehicle information detection unit 12030. The outside-vehicle information detection unit 12030 causes the imaging unit 12031 to capture images outside the vehicle and receives the captured images. The outside-vehicle information detection unit 12030 may perform object detection processing or distance detection processing for people, cars, obstacles, signs, characters on the road surface, etc., based on the received images.

[0178] The imaging unit 12031 is an optical sensor that receives light and outputs an electrical signal according to the amount of light received. The imaging unit 12031 can output the electrical signal as an image, or as distance measurement information. The light received by the imaging unit 12031 may be visible light or invisible light such as infrared light.

[0179] The in-vehicle information detection unit 12040 detects information inside the vehicle. For example, a driver state detection unit 12041 that detects the state of the driver is connected to the in-vehicle information detection unit 12040. The driver state detection unit 12041 includes, for example, a camera that captures an image of the driver, and the in-vehicle information detection unit 12040 may calculate the degree of fatigue or concentration of the driver based on the detection information input from the driver state detection unit 12041, or may determine whether the driver is dozing off.

[0180] The microcomputer 12051 can calculate control target values ​​for the driving force generating device, steering mechanism, or braking device based on the information inside and outside the vehicle acquired by the outside-vehicle information detection unit 12030 or the inside-vehicle information detection unit 12040, and output control commands to the drivetrain control unit 12010. For example, the microcomputer 12051 can perform cooperative control aimed at realizing the functions of an ADAS (Advanced Driver Assistance System), including avoiding or mitigating collisions between vehicles, following based on the distance between vehicles, maintaining vehicle speed, warning of vehicle collisions, or warning of vehicle lane departure.

[0181] In addition, the microcomputer 12051 can perform cooperative control for the purpose of autonomous driving, which allows the vehicle to travel autonomously without relying on driver operation, by controlling the driving force generating device, steering mechanism, braking device, etc. based on information about the surroundings of the vehicle obtained by the outside vehicle information detection unit 12030 or the inside vehicle information detection unit 12040.

[0182] Furthermore, the microcomputer 12051 can output a control command to the body system control unit 12020 based on the information about the outside of the vehicle acquired by the outside information detection unit 12030. For example, the microcomputer 12051 can control the headlamps according to the position of a preceding vehicle or an oncoming vehicle detected by the outside information detection unit 12030, and perform cooperative control for the purpose of preventing glare, such as switching from high beams to low beams.

[0183] The audio / video output unit 12052 transmits at least one output signal of audio and / or video to an output device capable of visually or audibly notifying information to passengers in the vehicle or to the outside of the vehicle. In the example of Fig. 20, an audio speaker 12061, a display unit 12062, and an instrument panel 12063 are exemplified as output devices. The display unit 12062 may include, for example, at least one of an on-board display and a head-up display.

[0184] FIG. 21 is a diagram showing an example of the installation position of the imaging unit 12031.

[0185] In FIG. 21, a vehicle 12100 has imaging units 12101, 12102, 12103, 12104, and 12105 as the imaging unit 12031.

[0186] The imaging units 12101, 12102, 12103, 12104, and 12105 are provided, for example, at positions such as the front nose, side mirrors, rear bumper, back door, and the top of the windshield inside the vehicle cabin of the vehicle 12100. The imaging unit 12101 provided at the front nose and the imaging unit 12105 provided at the top of the windshield inside the vehicle cabin mainly acquire images of the front of the vehicle 12100. The imaging units 12102 and 12103 provided at the side mirrors mainly acquire images of the sides of the vehicle 12100. The imaging unit 12104 provided at the rear bumper or back door mainly acquires images of the rear of the vehicle 12100. The forward images acquired by the imaging units 12101 and 12105 are mainly used to detect preceding vehicles, pedestrians, obstacles, traffic lights, traffic signs, lanes, etc.

[0187] 21 shows an example of the imaging ranges of the imaging units 12101 to 12104. Imaging range 12111 indicates the imaging range of the imaging unit 12101 provided on the front nose, imaging ranges 12112 and 12113 indicate the imaging ranges of the imaging units 12102 and 12103 provided on the side mirrors, respectively, and imaging range 12114 indicates the imaging range of the imaging unit 12104 provided on the rear bumper or back door. For example, by overlaying the image data captured by the imaging units 12101 to 12104, a bird's-eye view image of the vehicle 12100 viewed from above can be obtained.

[0188] At least one of the imaging units 12101 to 12104 may have a function of acquiring distance information. For example, at least one of the imaging units 12101 to 12104 may be a stereo camera made up of multiple imaging elements, or may be an imaging element having pixels for phase difference detection.

[0189] For example, the microcomputer 12051 can calculate the distance to each three-dimensional object within the imaging ranges 12111 to 12114 and the change in this distance over time (relative speed with respect to the vehicle 12100) based on the distance information obtained from the imaging units 12101 to 12104, thereby extracting as a preceding vehicle, in particular, the three-dimensional object that is the closest three-dimensional object on the path of the vehicle 12100 and traveling in approximately the same direction as the vehicle 12100 at a predetermined speed (for example, 0 km / h or higher). Furthermore, the microcomputer 12051 can set a vehicle-to-vehicle distance to be maintained in advance in front of the preceding vehicle, and perform automatic braking control (including follow-up stop control), automatic acceleration control (including follow-up start control), etc. In this way, cooperative control can be performed for the purpose of automatic driving, which runs autonomously without relying on driver operation.

[0190] For example, the microcomputer 12051 classifies and extracts three-dimensional object data regarding three-dimensional objects into two-wheeled vehicles, ordinary vehicles, large vehicles, pedestrians, utility poles, and other three-dimensional objects based on distance information obtained from the imaging units 12101 to 12104, and can use the data for automatic obstacle avoidance. For example, the microcomputer 12051 distinguishes obstacles around the vehicle 12100 into obstacles that are visible to the driver of the vehicle 12100 and obstacles that are difficult to see. The microcomputer 12051 then determines the collision risk, which indicates the degree of risk of collision with each obstacle, and when the collision risk is equal to or greater than a set value and a collision is possible, the microcomputer 12051 can provide driving assistance for collision avoidance by outputting an alarm to the driver via the audio speaker 12061 or the display unit 12062, or by performing forced deceleration or avoidance steering via the drivetrain control unit 12010.

[0191] At least one of the image capturing units 12101 to 12104 may be an infrared camera that detects infrared rays. For example, the microcomputer 12051 can recognize a pedestrian by determining whether or not a pedestrian is present in the images captured by the image capturing units 12101 to 12104. The pedestrian recognition is performed, for example, by extracting feature points from the images captured by the image capturing units 12101 to 12104, which are infrared cameras, and then performing pattern matching on a series of feature points that indicate the outline of an object to determine whether or not the object is a pedestrian. When the microcomputer 12051 determines that a pedestrian is present in the images captured by the image capturing units 12101 to 12104 and recognizes the pedestrian, the audio / image output unit 12052 controls the display unit 12062 to superimpose a rectangular outline on the recognized pedestrian for emphasis. The audio / image output unit 12052 may also control the display unit 12062 to display an icon or the like indicating the pedestrian at a desired position.

[0192] An example of a vehicle control system to which the technology according to the present disclosure can be applied has been described above. The technology according to the present disclosure can be applied to, for example, the imaging unit 12031 among the above-described configurations. Specifically, the above-described light detection device 1 can be applied to the imaging unit 12031. By applying the technology according to the present disclosure to the imaging unit 12031, it is possible to prevent insufficient bonding between the connection pads of the imaging unit 12031, thereby improving the reliability of the imaging unit 12031.

[0193] <3. Application example to endoscopic surgery system> The technology according to the present disclosure (the present technology) can be applied to various products. For example, the technology according to the present disclosure may be applied to an endoscopic surgery system.

[0194] FIG. 22 is a diagram showing an example of a schematic configuration of an endoscopic surgery system to which the technology according to the present disclosure (the present technology) can be applied.

[0195] 22 shows an operator (doctor) 11131 performing surgery on a patient 11132 on a patient bed 11133 using an endoscopic surgery system 11000. As shown in the figure, the endoscopic surgery system 11000 is composed of an endoscope 11100, other surgical instruments 11110 such as an insufflation tube 11111 and an energy treatment instrument 11112, a support arm device 11120 that supports the endoscope 11100, and a cart 11200 on which various devices for endoscopic surgery are mounted.

[0196] The endoscope 11100 is composed of a lens barrel 11101, a region of a predetermined length from the tip of which is inserted into a body cavity of a patient 11132, and a camera head 11102 connected to the base end of the lens barrel 11101. In the example shown, the endoscope 11100 is configured as a so-called rigid scope having a rigid lens barrel 11101, but the endoscope 11100 may also be configured as a so-called flexible scope having a flexible lens barrel.

[0197] An opening into which an objective lens is fitted is provided at the tip of the lens barrel 11101. A light source device 11203 is connected to the endoscope 11100, and light generated by the light source device 11203 is guided to the tip of the lens barrel by a light guide extending inside the lens barrel 11101, and is irradiated via the objective lens towards an object to be observed inside the body cavity of the patient 11132. The endoscope 11100 may be a direct-viewing endoscope, an oblique-viewing endoscope, or a side-viewing endoscope.

[0198] An optical system and an image sensor are provided inside the camera head 11102, and light reflected from the object of observation (observation light) is collected onto the image sensor by the optical system. The observation light is photoelectrically converted by the image sensor to generate an electrical signal corresponding to the observation light, i.e., an image signal corresponding to the observed image. The image signal is sent to a camera control unit (CCU) 11201 as RAW data.

[0199] The CCU 11201 is configured with a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), etc., and comprehensively controls the operations of the endoscope 11100 and the display device 11202. Furthermore, the CCU 11201 receives an image signal from the camera head 11102, and performs various image processing on the image signal, such as development processing (demosaic processing), to display an image based on the image signal.

[0200] Under the control of the CCU 11201, the display device 11202 displays an image based on an image signal that has been subjected to image processing by the CCU 11201.

[0201] The light source device 11203 is configured from a light source such as an LED (Light Emitting Diode), and supplies irradiation light to the endoscope 11100 when photographing an operation site or the like.

[0202] The input device 11204 is an input interface for the endoscopic surgery system 11000. A user can input various information and instructions to the endoscopic surgery system 11000 via the input device 11204. For example, the user inputs an instruction to change the imaging conditions (type of irradiating light, magnification, focal length, etc.) of the endoscope 11100.

[0203] The treatment tool control device 11205 controls the driving of the energy treatment tool 11112 for cauterizing tissue, incising, sealing blood vessels, etc. The insufflation device 11206 inflates the body cavity of the patient 11132 through the insufflation tube 11111 in order to ensure a clear field of view for the endoscope 11100 and a working space for the surgeon. The recorder 11207 is a device capable of recording various types of information related to the surgery. The printer 11208 is a device capable of printing various types of information related to the surgery in various formats such as text, images, or graphs.

[0204] The light source device 11203 that supplies illumination light to the endoscope 11100 when photographing the surgical site can be configured from a white light source configured from, for example, an LED, a laser light source, or a combination of these. When the white light source is configured from a combination of RGB laser light sources, the output intensity and output timing of each color (each wavelength) can be controlled with high precision, making it possible to adjust the white balance of the captured image in the light source device 11203. In this case, it is also possible to capture images corresponding to each RGB in a time-division manner by irradiating the object of observation with laser light from each RGB laser light source in a time-division manner and controlling the drive of the image sensor of the camera head 11102 in synchronization with the irradiation timing. According to this method, a color image can be obtained without providing a color filter to the image sensor.

[0205] Furthermore, the light source device 11203 may be controlled to change the intensity of light it outputs at predetermined time intervals. By controlling the driving of the image sensor of the camera head 11102 in synchronization with the timing of the change in light intensity to acquire images in a time-division manner and combining the images, it is possible to generate an image with a high dynamic range that is free of so-called blocked-up shadows and blown-out highlights.

[0206] The light source device 11203 may also be configured to supply light in a predetermined wavelength band corresponding to special light observation. Special light observation, for example, utilizes the wavelength dependence of light absorption in body tissues to irradiate light with a narrower band than the light irradiated during normal observation (i.e., white light), thereby capturing high-contrast images of specific tissues, such as blood vessels on the surface of mucous membranes, known as narrow-band imaging. Alternatively, special light observation may be performed using fluorescence observation, in which images are obtained using fluorescence generated by irradiating excitation light. Fluorescence observation can involve irradiating excitation light onto body tissues and observing the fluorescence from the tissues (autofluorescence observation), or locally injecting a reagent such as indocyanine green (ICG) into the body tissue and irradiating the tissue with excitation light corresponding to the fluorescent wavelength of the reagent to obtain a fluorescent image. The light source device 11203 may be configured to supply narrow-band light and / or excitation light corresponding to such special light observation.

[0207] FIG. 23 is a block diagram showing an example of the functional configuration of the camera head 11102 and the CCU 11201 shown in FIG.

[0208] The camera head 11102 has a lens unit 11401, an imaging unit 11402, a drive unit 11403, a communication unit 11404, and a camera head control unit 11405. The CCU 11201 has a communication unit 11411, an image processing unit 11412, and a control unit 11413. The camera head 11102 and the CCU 11201 are connected to each other by a transmission cable 11400 so that they can communicate with each other.

[0209] The lens unit 11401 is an optical system provided at the connection point with the lens barrel 11101. Observation light taken in from the tip of the lens barrel 11101 is guided to the camera head 11102 and enters the lens unit 11401. The lens unit 11401 is composed of a combination of multiple lenses including a zoom lens and a focus lens.

[0210] The imaging unit 11402 is configured with an imaging element. The imaging element constituting the imaging unit 11402 may be one (a so-called single-chip type) or multiple (a so-called multi-chip type). When the imaging unit 11402 is configured with a multi-chip type, for example, each imaging element may generate an image signal corresponding to each of RGB, and a color image may be obtained by combining these signals. Alternatively, the imaging unit 11402 may be configured with a pair of imaging elements for acquiring image signals for the right eye and the left eye corresponding to 3D (dimensional) display. 3D display enables the surgeon 11131 to more accurately grasp the depth of the biological tissue at the surgical site. Note that when the imaging unit 11402 is configured with a multi-chip type, multiple lens units 11401 may be provided corresponding to each imaging element.

[0211] Furthermore, the imaging unit 11402 does not necessarily have to be provided in the camera head 11102. For example, the imaging unit 11402 may be provided inside the lens barrel 11101, immediately after the objective lens.

[0212] The driving unit 11403 is configured by an actuator, and moves the zoom lens and focus lens of the lens unit 11401 by a predetermined distance along the optical axis under the control of the camera head control unit 11405. This allows the magnification and focus of the image captured by the imaging unit 11402 to be adjusted appropriately.

[0213] The communication unit 11404 is configured by a communication device for transmitting and receiving various types of information to and from the CCU 11201. The communication unit 11404 transmits the image signal obtained from the imaging unit 11402 to the CCU 11201 via the transmission cable 11400 as RAW data.

[0214] Furthermore, the communication unit 11404 receives a control signal for controlling the driving of the camera head 11102 from the CCU 11201 and supplies the control signal to the camera head control unit 11405. The control signal includes information on the imaging conditions, such as information specifying the frame rate of the captured image, information specifying the exposure value at the time of imaging, and / or information specifying the magnification and focus of the captured image.

[0215] The image capturing conditions such as the frame rate, exposure value, magnification, and focus may be appropriately specified by the user, or may be automatically set by the control unit 11413 of the CCU 11201 based on the acquired image signal. In the latter case, the endoscope 11100 is equipped with so-called AE (Auto Exposure) function, AF (Auto Focus) function, and AWB (Auto White Balance) function.

[0216] The camera head control unit 11405 controls the driving of the camera head 11102 based on a control signal received from the CCU 11201 via the communication unit 11404 .

[0217] The communication unit 11411 is configured by a communication device for transmitting and receiving various information to and from the camera head 11102. The communication unit 11411 receives an image signal transmitted from the camera head 11102 via the transmission cable 11400.

[0218] Furthermore, the communication unit 11411 transmits to the camera head 11102 a control signal for controlling the driving of the camera head 11102. The image signal and the control signal can be transmitted by electrical communication, optical communication, or the like.

[0219] The image processing unit 11412 performs various image processing operations on the image signal, which is RAW data sent from the camera head 11102 .

[0220] The control unit 11413 performs various controls related to the imaging of the surgical site, etc. by the endoscope 11100 and the display of the captured image obtained by imaging the surgical site, etc. For example, the control unit 11413 generates a control signal for controlling the driving of the camera head 11102.

[0221] Furthermore, the control unit 11413 causes the display device 11202 to display a captured image showing the surgical site, etc., based on the image signal that has been image processed by the image processing unit 11412. At this time, the control unit 11413 may recognize various objects in the captured image using various image recognition technologies. For example, the control unit 11413 can recognize surgical tools such as forceps, specific biological parts, bleeding, mist generated when using the energy treatment tool 11112, etc., by detecting the shape and color of the edges of objects included in the captured image. When displaying the captured image on the display device 11202, the control unit 11413 may use the recognition results to superimpose various surgical support information on the image of the surgical site. By superimposing the surgical support information and presenting it to the surgeon 11131, the burden on the surgeon 11131 can be reduced and the surgeon 11131 can proceed with the surgery reliably.

[0222] The transmission cable 11400 connecting the camera head 11102 and the CCU 11201 is an electrical signal cable for communication of electrical signals, an optical fiber for optical communication, or a composite cable of these.

[0223] In the illustrated example, communication is performed by wire using the transmission cable 11400, but communication between the camera head 11102 and the CCU 11201 may also be performed wirelessly.

[0224] The foregoing has described an example of an endoscopic surgery system to which the technology according to the present disclosure can be applied. The technology according to the present disclosure can be applied to, for example, the imaging unit 11402 of the camera head 11102 among the configurations described above. Specifically, the above-described light detection device 1 can be applied to the imaging unit 11402. By applying the technology according to the present disclosure to the imaging unit 11402, it is possible to prevent insufficient bonding between the connection pads of the imaging unit 11402, thereby improving the reliability of the imaging unit 11402.

[0225] Although an endoscopic surgery system has been described as an example here, the technology according to the present disclosure may also be applied to other systems, such as a microsurgery system.

[0226] [Other embodiments] As described above, the present technology has been described by a number of embodiments, but the descriptions and drawings that form part of this disclosure should not be understood to limit the present technology. Various alternative embodiments, examples, and operating techniques will become apparent to those skilled in the art from this disclosure.

[0227] For example, it is possible to combine the technical concepts described in the first to third embodiments. For example, the column configuration according to the first embodiment, the connection pad configuration according to the second embodiment, and the insulating film db configuration according to the third embodiment may all be combined, or two of them may be combined. By combining at least two of these embodiments, it is possible to further prevent insufficient bonding between the connection pads.

[0228] Furthermore, in the photodetector 1 according to the second embodiment, the insulating films 31A, 41A, 61A, and 71A may be made of a first material that is a low-dielectric-constant (Low-K) insulating material. In the photodetector 1 according to the second embodiment of the present technology, the expansion amount of the first portion a can be prevented from being affected by the barrier metal layer f, so even if the insulating film is made of the first material, deterioration of contact between the connection pads can be prevented. Furthermore, at least a portion of each of the insulating films 31A, 41A, 61A, and 71A may be made of the first material that is a low-dielectric-constant (Low-K) insulating material. Similarly, in the photodetector 1 according to the third embodiment, the insulating film da may be made of the first material that is a low-dielectric-constant (Low-K) insulating material. In the photodetector 1 according to the third embodiment of the present technology, the expansion amount of the insulating film db can be prevented, so even if the insulating film da is made of the first material, deterioration of contact between the connection pads can be prevented. Furthermore, at least a portion of the insulating film da of each wiring layer may be made of the first material that is a low-dielectric-constant (Low-K) insulating material. In this way, various combinations are possible in accordance with the respective technical concepts.

[0229] Furthermore, although the above-described photodetector 1 has three semiconductor layers, the present invention is not limited to this and may have at least two semiconductor layers.

[0230] Furthermore, the present technology can be applied to photodetection devices in general, including not only the solid-state imaging device as the image sensor described above but also distance measurement sensors, also known as ToF (Time of Flight) sensors, that measure distance. A distance measurement sensor emits light toward an object, detects the light reflected by the surface of the object, and calculates the distance to the object based on the time of flight from when the light is emitted until when the reflected light is received. The structure of the connection pad and insulating film described above can be adopted as the structure of this distance measurement sensor. The present technology can also be applied to semiconductor devices other than the photodetection device 1.

[0231] As such, the present technology naturally includes various embodiments not described herein. Therefore, the technical scope of the present technology is defined only by the invention-specifying matters described in the claims that are appropriate from the above description.

[0232] Furthermore, the effects described in this specification are merely examples and are not limiting, and other effects may also be present.

[0233] The present technology may be configured as follows. (1) at least two semiconductor layers; a wiring layer on one side in the stacking direction and a wiring layer on the other side in the stacking direction, which are interposed between the semiconductor layers, each including an insulating film and a connection pad provided on the insulating film, and which are electrically coupled to each other by joining surfaces of the connection pads; Equipped with the semiconductor layer on the light incident surface side of the at least two semiconductor layers has a photoelectric conversion region; the insulating film includes a first insulating film and a second insulating film made of a material having higher rigidity than a material constituting the first insulating film and penetrating the first insulating film in a stacking direction; The photodetector device, wherein the second insulating film is provided between the connection pad and at least one of the semiconductor layers. (2) the second insulating film includes a columnar portion extending along a stacking direction, The photodetector according to (1), wherein one end of the columnar portion in the stacking direction is in contact with the connection pad and the other end is in contact with the semiconductor layer. (3) The photodetector according to (2), wherein the columnar portion is provided at a position that does not overlap with wiring formed on the insulating film in the stacking direction. (4) The photodetector according to (2) or (3), wherein a plurality of the columnar portions are provided for each of the connection pads. (5) The photodetector according to any one of (1) to (4), wherein the dielectric constant of the material constituting the first insulating film is lower than the dielectric constant of the material constituting the second insulating film. (6) The photodetector according to any one of (1) to (5), wherein the material constituting the second insulating film is silicon oxide, silicon nitride, or silicon oxide and silicon nitride. (7) at least two semiconductor layers; a wiring layer on one side in the stacking direction and a wiring layer on the other side in the stacking direction, which are interposed between the semiconductor layers, each including an insulating film and a connection pad provided on the insulating film, and which are electrically coupled to each other by joining surfaces of the connection pads; Equipped with the semiconductor layer on the light incident surface side of the at least two semiconductor layers has a photoelectric conversion region; a photodetector device, wherein at least one of the connection pads has a first portion made of a first metal and constituting the surface of the connection pad, and a second portion made of a second metal that is more susceptible to plastic deformation than the first metal and is provided between the first portion and the insulating film. (8) The photodetector according to (7), wherein the second portion is provided at least between a side surface of the first portion and the insulating film. (9) The light detection device according to (7) or (8), wherein the melting point of the second metal is lower than the melting point of the first metal. (10) The photodetector device according to any one of (7) to (9), wherein the second portion is a seed layer that functions as a base for depositing the first metal, or a barrier metal layer that suppresses the first metal from diffusing into the insulating film. (11) the first metal is copper; The photodetector according to any one of (7) to (10), wherein the second metal is aluminum, an aluminum-copper alloy, an aluminum-silicon alloy, cadmium, tin, tantalum, lead, a lead-copper alloy, antimony, ytterbium, calcium, silver, germanium, strontium, or cerium. (12) at least two semiconductor layers; a wiring layer on one side in the stacking direction and a wiring layer on the other side in the stacking direction, which are interposed between the semiconductor layers, each including an insulating film and a connection pad provided on the insulating film, and which are electrically coupled to each other by joining surfaces of the connection pads; Equipped with the semiconductor layer on the light incident surface side of the at least two semiconductor layers has a photoelectric conversion region; A photodetector device, wherein the linear expansion coefficient of the material constituting a third portion of the insulating film, which is adjacent to the side surface of the connection pad, is smaller than the linear expansion coefficient of the material constituting a fourth portion, which is adjacent to the bottom surface of the connection pad. (13) The light detection device according to (12), wherein the material constituting the third portion is glass ceramic whose linear expansion coefficient is adjusted by an additive. (14) The light detection device according to (12), wherein the material constituting the third portion has a negative linear expansion coefficient. (15) The optical detection device according to (14), wherein the material constituting the third portion includes at least one of cubic zirconium tungstate, Cu-Zn-VO-based oxide, zirconium phosphate, zirconium tungstate phosphate, and a filler made of glass having a negative linear expansion coefficient. (16) The photodetector according to any one of (12) to (15), wherein at least one of a silicon oxide film, a silicon nitride film, a silicon carbonitride film, a carbon-containing silicon oxide film, a silicon carbide film, an aluminum oxide film, and a tantalum oxide film is provided between the third portion and the fourth portion. (17) a light detection device; and an optical system that forms an image of image light from a subject on the light detection device, The photodetector device at least two semiconductor layers; a wiring layer on one side in the stacking direction and a wiring layer on the other side in the stacking direction, which are interposed between the semiconductor layers, each including an insulating film and a connection pad provided on the insulating film, and which are electrically coupled to each other by joining surfaces of the connection pads; Equipped with the semiconductor layer on the light incident surface side of the at least two semiconductor layers has a photoelectric conversion region; the insulating film includes a first insulating film and a second insulating film made of a material having higher rigidity than a material constituting the first insulating film and penetrating the first insulating film in a stacking direction; The electronic device, wherein the second insulating film is provided between the connection pad and at least one of the semiconductor layers. (18) a light detection device; and an optical system that forms an image of image light from a subject on the light detection device, The photodetector device at least two semiconductor layers; a wiring layer on one side in the stacking direction and a wiring layer on the other side in the stacking direction, which are interposed between the semiconductor layers, each including an insulating film and a connection pad provided on the insulating film, and which are electrically coupled to each other by joining surfaces of the connection pads; Equipped with the semiconductor layer on the light incident surface side of the at least two semiconductor layers has a photoelectric conversion region; an electronic device, wherein at least one of the connection pads has a first portion made of a first metal and constituting the surface of the connection pad, and a second portion made of a second metal that is more susceptible to plastic deformation than the first metal and is provided between the first portion and the insulating film. (19) a light detection device; and an optical system that forms an image of image light from a subject on the light detection device, The photodetector device at least two semiconductor layers; a wiring layer on one side in the stacking direction and a wiring layer on the other side in the stacking direction, which are interposed between the semiconductor layers, each including an insulating film and a connection pad provided on the insulating film, and which are electrically coupled to each other by joining surfaces of the connection pads; Equipped with the semiconductor layer on the light incident surface side of the at least two semiconductor layers has a photoelectric conversion region; an insulating film having a third portion adjacent to the side surface of the connection pad, the third portion having a linear expansion coefficient smaller than a fourth portion having a linear expansion coefficient smaller than a fourth portion adjacent to the bottom surface of the connection pad;

[0234] The scope of the present technology is not limited to the exemplary embodiments shown and described, but includes all embodiments that achieve equivalent effects to those intended by the present technology. Furthermore, the scope of the present technology is not limited to the combination of the features of the invention defined by the claims, but may be defined by any desired combination of specific features among all the respective disclosed features. [Explanation of symbols]

[0235] 1. Photodetector 2. Semiconductor chips 2A Pixel area 2B Peripheral Area 3 pixels 4 Vertical drive circuit 5 Column signal processing circuit 6 Horizontal drive circuit 7 Output circuit 8 Control Circuit 10 pixel drive lines 11 Vertical signal line 12 Horizontal signal line 13 Logic Circuits 14 Bonding Pads 15 Readout circuit 20 First semiconductor layer 20a Photoelectric conversion region 30 1st wiring layer 31, 31A, 31B insulating film 32 Wiring 33 First connection pad 35 First insulating film 36 Second insulating film 40 2nd wiring layer 41, 41A, 41B insulating film 42 Wiring 43 Second connection pad 43a bottom 45 First insulating film 46 Second insulating film 50 Second semiconductor layer 60 3rd wiring layer 61, 61A, 61B insulating film 62 Wiring 63 Third connection pad 63a Bottom 63S surface 65 First insulating film 66 Second insulating film 70 4th wiring layer 71, 71A, 71B insulating film 72 Wiring 73 4th connection pad 73S surface 75 First insulating film 76 Second insulating film 80 Third semiconductor layer 100 Electronic equipment 101 Solid-state imaging device 102 Optical Systems (Optical Lenses) 103 Shutter device 104 Drive circuit 105 Signal Processing Circuit a First part A, A1, A2, B connection pads Connection Pad b Second part b1 Side wall B1 side B2 Bottom c seed layer d insulating film da,da31,da41,da61,da71 insulating film db,db31,db41,db61,db71 insulating film f Barrier metal layer g contact layer P,P1,Pa,Pb pillar

Claims

1. at least two semiconductor layers; a wiring layer on one side in the stacking direction and a wiring layer on the other side in the stacking direction, which are interposed between the semiconductor layers, each including an insulating film and a connection pad provided on the insulating film, and which are electrically coupled to each other by joining surfaces of the connection pads; Equipped with the semiconductor layer on the light incident surface side of the at least two semiconductor layers has a photoelectric conversion region; the insulating film includes a first insulating film and a second insulating film made of a material having higher rigidity than a material constituting the first insulating film and penetrating the first insulating film in a stacking direction; The second insulating film is provided between the connection pad and at least one of the semiconductor layers.

2. the second insulating film includes a columnar portion extending along a stacking direction, The photodetector according to claim 1 , wherein one end of the columnar portion in the stacking direction is in contact with the connection pad, and the other end is in contact with the semiconductor layer.

3. The photodetector according to claim 2 , wherein the columnar portion is provided at a position that does not overlap with a wiring formed on the insulating film in a stacking direction.

4. The photodetector according to claim 3 , wherein a plurality of the columnar portions are provided for each of the connection pads.

5. 2. The photodetector according to claim 1, wherein a dielectric constant of a material constituting said first insulating film is lower than a dielectric constant of a material constituting said second insulating film.

6. 2. The photodetector according to claim 1, wherein the material forming the second insulating film is silicon oxide, silicon nitride, or a combination of silicon oxide and silicon nitride.

7. at least two semiconductor layers; a wiring layer on one side in the stacking direction and a wiring layer on the other side in the stacking direction, which are interposed between the semiconductor layers, each including an insulating film and a connection pad provided on the insulating film, and which are electrically coupled to each other by joining surfaces of the connection pads; Equipped with the semiconductor layer on the light incident surface side of the at least two semiconductor layers has a photoelectric conversion region; At least one of the connection pads has a first portion made of a first metal and constituting a surface of the connection pad, and a second portion made of a second metal that is more easily plastically deformed than the first metal and is provided between the first portion and the insulating film, a barrier metal layer provided between the second portion and the insulating film; Light detection device.

8. The photodetector according to claim 7 , wherein the second portion is provided at least between a side surface of the first portion and the insulating film.

9. The photodetector device according to claim 7 , wherein the melting point of the second metal is lower than the melting point of the first metal.

10. The photodetector device according to claim 7 , wherein the second portion is a seed layer that functions as a base for depositing the first metal, and the barrier metal layer suppresses diffusion of the first metal into the insulating film.

11. the first metal is copper; 8. The photodetector device according to claim 7, wherein the second metal is aluminum, an aluminum-copper alloy, an aluminum-silicon alloy, cadmium, tin, tantalum, lead, a lead-copper alloy, antimony, ytterbium, calcium, silver, germanium, strontium, or cerium.

12. at least two semiconductor layers; a wiring layer on one side in the stacking direction and a wiring layer on the other side in the stacking direction, which are interposed between the semiconductor layers, each including an insulating film and a connection pad provided on the insulating film, and which are electrically coupled to each other by joining surfaces of the connection pads; Equipped with the semiconductor layer on the light incident surface side of the at least two semiconductor layers has a photoelectric conversion region; A photodetector device, wherein the linear expansion coefficient of the material constituting the third portion of the insulating film, which is adjacent to the side of the connection pad, is smaller than the linear expansion coefficient of the material constituting the fourth portion, which is adjacent to the bottom surface of the connection pad.

13. 13. The light detection device according to claim 12, wherein the material constituting the third portion is glass ceramic whose linear expansion coefficient is adjusted by an additive.

14. The light detection device according to claim 12 , wherein the material constituting the third portion has a negative linear expansion coefficient.

15. 15. The light detection device according to claim 14, wherein a material constituting the third portion includes at least one of cubic zirconium tungstate, Cu-Zn-VO-based oxide, zirconium phosphate, zirconium tungstate phosphate, and a filler made of glass having a negative linear expansion coefficient.

16. 13. The photodetector device according to claim 12, wherein at least one of a silicon oxide film, a silicon nitride film, a silicon carbonitride film, a carbon-containing silicon oxide film, a silicon carbide film, an aluminum oxide film, and a tantalum oxide film is provided between the third portion and the fourth portion.

17. a light detection device; and an optical system that forms an image of image light from a subject on the light detection device, The photodetector device at least two semiconductor layers; a wiring layer on one side in the stacking direction and a wiring layer on the other side in the stacking direction, which are interposed between the semiconductor layers, each including an insulating film and a connection pad provided on the insulating film, and which are electrically coupled to each other by joining surfaces of the connection pads; Equipped with the semiconductor layer on the light incident surface side of the at least two semiconductor layers has a photoelectric conversion region; the insulating film includes a first insulating film and a second insulating film made of a material having higher rigidity than a material constituting the first insulating film and penetrating the first insulating film in a stacking direction; The electronic device, wherein the second insulating film is provided between the connection pad and at least one of the semiconductor layers.

Images