JP6700715B2 - Solid-state imaging device and manufacturing method thereof - Google Patents

Description

  The present invention relates to a solid-state imaging device and a method for manufacturing the same.

  2. Description of the Related Art Conventionally, some image pickup apparatuses such as digital still cameras and digital video cameras are equipped with a CMOS image sensor as a solid-state image pickup element. These solid-state image pickup devices have an image pickup surface composed of pixel portions including photoelectric conversion elements. A lens is used for the purpose of forming an image of a subject on this imaging surface. Generally, when an image of a subject is formed by a lens, a focus position shift occurs between the central portion and the peripheral portion of the image pickup surface due to field curvature. In order to solve this problem, a technique of bending the solid-state imaging device itself has been proposed (see Patent Document 1).

  In addition, a technique has been proposed for mounting the curved solid-state imaging device on a signal processing substrate that processes an imaging signal output from a pixel unit (see Patent Document 2). In Patent Document 2, a plurality of bumps having different sizes in the thickness direction are used when electrically connecting the solid-state imaging device and the signal processing substrate. By this method, the curved solid-state imaging device and the signal processing board are laminated.

JP, 2008-294960, A JP, 2009-049499, A

  However, in the method described in Patent Document 2, the impedance of each bump may be different because a plurality of bumps having different sizes in the thickness direction are used to connect the solid-state imaging device and the signal processing substrate. I'm worried. As a result, the voltage of the image pickup signal from the solid-state image pickup device may change, and a signal different from the original voltage level is input to the substrate, which may cause deterioration of image quality.

  The present invention has been made to solve the above problems. INDUSTRIAL APPLICABILITY The present invention suppresses the occurrence of a shift in the focal position due to field curvature, suppresses the voltage change of the image pickup signal that occurs due to the difference in impedance of each bump, and prevents the deterioration of image quality. It is an object of the present invention to provide a solid-state imaging device having high efficiency and a manufacturing method thereof.

The solid-state imaging device of the present invention includes a first substrate which is a solid-state imaging device having a non-planar first surface, and a second substrate having a second surface having a shape different from the first surface, A plurality of bumps electrically connecting the first substrate and the second substrate are provided, and the plurality of bumps are provided between the first surface and the second surface facing each other. , The first surface and the second surface are arranged at positions where respective perpendiculars of the first surface and the second surface overlap , and the first substrate and the second substrate are respectively arranged on the first surface and the second surface. The existing virtual lines having the same curvature are electrically connected by the plurality of bumps .

A method for manufacturing a solid-state imaging device according to the present invention includes a first substrate which is a solid-state imaging device having a non-planar first surface, and a second substrate having a second surface having a shape different from the first surface. a substrate, in electrical connection with a plurality of bumps, each of the perpendicular of the first surface and the second surface and a pair countercurrent Toe Rutotomoni the first surface and the second surface The plurality of bumps are arranged at a position where they overlap each other, and the first substrate and the second substrate are formed between virtual lines existing on the first surface and the second surface and having the same curvature. Are electrically connected by the plurality of bumps .

  According to the present invention, it is possible to prevent the occurrence of the shift of the focal position due to the curvature of field and the like, and to suppress the voltage change of the image pickup signal caused by the different impedance of each bump, thereby preventing the deterioration of the image quality. A highly reliable solid-state imaging device is realized.

It is a schematic diagram which shows the external appearance of the solid-state imaging device in 1st Embodiment. It is a schematic diagram showing the composition of the 1st substrate of the solid-state imaging device in a 1st embodiment. It is an equivalent circuit diagram which shows the structure of the 1st board|substrate and 2nd board|substrate of the solid-state imaging device in 1st Embodiment. FIG. 3 is a block diagram showing a configuration of a second substrate of the solid-state imaging device according to the first embodiment, and a relationship between a pixel portion of the first substrate and the second substrate. It is a schematic diagram which shows the external appearance of the solid-state imaging device in 2nd Embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

(First embodiment)
1A and 1B are schematic diagrams showing the appearance of the solid-state imaging device according to the first embodiment. FIG. 1A is a perspective view and FIG. 1B is a cross-sectional view taken along a broken line (curve 113).
This solid-state imaging device includes a first substrate 101 having a non-planar first surface 101a and a second substrate 102 having a non-planar second surface 102a different from the first surface 101a. Is configured. The 1st board|substrate 101 and the 2nd board|substrate 102 are laminated|stacked by making the 1st and 2nd surfaces 101a and 102a face each other, and joining.

The first substrate 101 is a solid-state image sensor, the first surface 101a is curved so as to have a convex spherical shape, and a plurality of pixel portions including photoelectric conversion elements are two-dimensionally arranged in a row direction and a column direction. Has been done. The curved shape of the first substrate 101 is a shape that is optically suitable for an optical system (not shown) of the solid-state imaging device.
The second substrate 102 is curved so that the second surface 102a has a concave cylindrical surface shape, and has a circuit configuration for reading an imaging signal output from the pixel portion of the first substrate 101.

  The first substrate 101 and the second substrate 102 are electrically connected by bumps 103 such as solder that join the first surface 101a and the second surface 102a. Virtual lines (curves 111 and 112) having the same curvature are present on the first surface 101a and the second surface 102a, respectively. On the curves 111 and 112, the respective perpendiculars of the first surface 101a and the second surface 102a overlap. The distance between the curves 111 and 112 is the shortest distance between the first surface 101 and the second substrate 102. Between the curves 111 and 112, a plurality of bumps 103 are arranged at equal intervals at positions where the respective normals of the first surface 101a and the second surface 102a overlap, and the first surface 101a and the second surface 102a Are joined. A curve that passes through the centers of the plurality of bumps 103 and is parallel to the curves 111 and 112 is shown as a curve 113 by a broken line. When the solid-state imaging device in which the first substrate 101 and the second substrate 102 are stacked is viewed from the upper surface or the lower surface, the plurality of bumps 103 are observed to be arranged on a straight line. The curves 111 and 112 are parallel curves, and the distance between them is equal. Therefore, the plurality of bumps 103 can have the same size.

Hereinafter, a method of connecting the first substrate 101 and the second substrate 102 when manufacturing the solid-state imaging device of this embodiment will be described.
The first substrate 101 and the second substrate 102, the first surface 101a and the second surface 102a, and the perpendicular lines of the first surface 101a and the second surface 102a are overlapped with each other (curve 111, The bumps 103 are opposed to each other at positions where the bumps 112 are parallel to each other. A plurality of bumps 103 having the same size are arranged along the curve 113 between the first substrate 101 and the second substrate 102. The first substrate 101 and the second substrate 102 are pressure bonded. At this time, the curve 111 of the first substrate 101 and the curve 112 of the second substrate 102 are parallel to each other, and even if the distance between them is shortened by pressure bonding, the distance is kept constant along the curves 111 and 112. Be drunk Therefore, even if the bumps 103 having the same size are used, one end of each bump 103 is connected to a bump pad 204 described later arranged on the curve 111, and the other end of the bump 103 is arranged on the curve 112. It is connected to the pad 204. Each bump 103 is connected to the first substrate 101 and the second substrate 102 along the curve 113 in a uniform state.

FIG. 2 is a schematic diagram showing the configuration of the first substrate of the solid-state imaging device according to the first embodiment.
The first substrate 101 includes a pixel section 200, a vertical scanning circuit 201, a vertical output line 202, a load current source 203, and a bump pad 204. The plurality of pixel units 200 are two-dimensionally arranged in the row direction and the column direction. The detailed configuration of the pixel unit 200 will be described later. The vertical scanning circuit 201 supplies the signals φTXn, φRESn, and the signal φSELn to the pixel portion 200, and controls signal reading. The load current source 203 drives the source follower 304 of the selected row described later in FIG. 3 via the vertical output line 202. The vertical output line 202 is a signal line that outputs the image pickup signal from the pixel unit 200 for each column. The bump pad 204 is a pad for electrically bonding the first substrate 101 and the bump 103 in FIG. 1 and outputs an image pickup signal from the vertical output line 202 to the bump 103. The bumps 103 are arranged on a line orthogonal to the vertical output line 202.

FIG. 3 is an equivalent circuit diagram showing the configurations of the first substrate and the second substrate of the solid-state imaging device according to the first embodiment.
The pixel portion 200, which is a component of the first substrate 101, includes a photodiode 300, a transfer gate 301, a reset switch 302, a storage capacitor 303, a source follower 304, and a row selection switch 305. The photodiode 300, which functions as a photoelectric conversion element, generates and accumulates signal charges according to the applied light. ON/OFF of the transfer gate 301 is controlled by the signal φTXn, and transfers the signal charge generated and accumulated in the photodiode 300 to the storage capacitor 303. The storage capacitor 303 stores the signal charge transferred by the transfer gate 301. The reset switch 302 is ON/OFF-controlled by the signal φRESn, and resets unnecessary signal charges stored in the photodiode 300 or the storage capacitor 303.

  The source follower 304 amplifies the signal charge stored in the storage capacitor 303 and converts it into a voltage. The reset switch 302, the storage capacitor 303, and the source follower 304 form a floating diffusion amplifier. The row selection switch 305 is turned on/off by a signal φSELn, and controls the output of the source follower 304 and the connection of the vertical output line 202. The imaging signal output from the pixel unit 200 is output to the bump 103 via the bump pad 204 as described above.

  The second substrate 102 includes a read circuit (AFE) 306, a digital signal processing circuit (DSP) 307, and bump pads 204. The AFE 306 performs noise reduction processing, analog-digital conversion, and the like on the signal output from the first substrate 101. The DSP 307 performs signal processing such as image processing and image compression on the digital signal output from the AFE 306. The imaging signal output from the first substrate 101 via the bumps 103 is input to the second substrate 102 from the bump pads 204 arranged on the second substrate 102. A detailed description of the second substrate 102 will be given later.

  FIG. 4 is a block diagram showing the configuration of the second substrate of the solid-state imaging device according to the first embodiment and the relationship between the pixel portion of the first substrate and the second substrate. In FIG. 4, for convenience, only one pixel portion 200 of the first substrate 101 is shown.

  The solid-state imaging device 400 of this embodiment is configured to include a first substrate 101 and a second substrate 102. As described above, in the first substrate 101, the pixel portion 200 converts light into an image pickup signal and outputs the image pickup signal to the bump 103. The image pickup signal output from the first substrate 101 is input to the AFE 306 in the second substrate 102 via the bump 103. The AFE 306 includes a correlated double sampling circuit (CDS) 401, an AD conversion circuit 402, and the like. The CDS 401 reduces noise in the input image pickup signal, and the AD conversion circuit 402 performs AD conversion processing to generate a digital signal. The DSP 307 performs various types of image processing and compression processing on the digital signal output from the AD conversion circuit 402 to generate image data. The generated image data is output to the outside of the solid-state image sensor 400.

  In the solid-state imaging device according to the present embodiment, although the curved first and second substrates 101 and 102 are used, a plurality of bumps 103 having the same size can be used for electrical connection between them. . The bumps 103 connect the first and second substrates 101 and 102 in a uniform state. With this structure, the curved first and second substrates 101 and 102 can be used to suppress the occurrence of a shift in the focal position due to field curvature, but the impedance of each bump 103 can be made uniform.

  As described above, according to the present embodiment, it is possible to suppress the occurrence of the shift of the focal position due to the field curvature, and to suppress the voltage change of the image pickup signal generated due to the different impedance of each bump, thereby improving the image quality. A highly reliable solid-state imaging device that prevents deterioration is realized.

(Second embodiment)
5A and 5B are schematic diagrams illustrating the appearance of the solid-state imaging device according to the second embodiment, where FIG. 5A is a perspective view and FIG. 5B is a cross-sectional view taken along a broken line (straight line 513).
In this solid-state imaging device, a first substrate 501 having a non-planar first surface 501a and a second substrate 502 having a planar second surface 502a have first and second surfaces 501a. , 502a are opposed to each other and joined.

The first substrate 501 is a solid-state image sensor, and the first surface 501a is curved so as to have a convex cylindrical surface shape, and the photoelectric conversion element is formed in the same manner as in FIGS. 2 and 3 of the first embodiment. A plurality of pixel portions including the same are formed. The curved shape of the first substrate 501 is a shape that is optically suitable for an optical system (not shown) of the solid-state imaging device.
The second substrate 502 has a flat plate shape here so that the second surface 502a has a flat shape, and the second substrate 502 is formed from the pixel portion of the first substrate 501 as in FIGS. 3 and 4 of the first embodiment. It has a circuit configuration for reading the output imaging signal.

  The first substrate 501 and the second substrate 502 are electrically connected to each other by bumps 503 such as solder that join the first surface 501a and the second surface 502a. Virtual straight lines 511 and 512 are present on the first surface 501a and the second surface 502a, respectively. On the straight lines 511 and 512, the respective perpendiculars of the first surface 501a and the second surface 502a overlap. The distance between the straight lines 511 and 512 is the shortest distance between the first surface 501 and the second substrate 502. Between the straight lines 511 and 512, a plurality of bumps 503 are arranged at equal intervals at positions where the respective perpendiculars of the first surface 501a and the second surface 502a overlap, and the first surface 501a and the second surface 502a Are joined. A straight line passing through the centers of the plurality of bumps 503 and parallel to the straight lines 511 and 512 is shown as a straight line 513 by a broken line. The straight lines 511 and 512 are parallel and the distance between them is equal. Therefore, the plurality of bumps 503 can all have the same size.

Hereinafter, a method of connecting the first substrate 501 and the second substrate 502 when manufacturing the solid-state imaging device of this embodiment will be described.
The bumps 503 are formed on the first surface 501a and the second surface 502a at the positions where the perpendiculars of the first surface 501a and the second surface 502a overlap (the positions where the straight lines 511 and 512 are parallel to each other). Put them face to face. A plurality of bumps 503 having the same size are arranged along a straight line 513 between the first substrate 501 and the second substrate 502. The first substrate 501 and the second substrate 502 are pressure bonded. At this time, the straight line 511 of the first substrate 501 and the straight line 512 of the second substrate 502 are parallel to each other, and even if the distance between them is shortened by pressure bonding, the distance is kept constant along the straight lines 511 and 512. Be drunk Therefore, even if the bumps 503 having the same size are used, one end of each bump 503 is connected to the bump pad 204 arranged on the straight line 511 and the other end of the bump 503 is arranged on the straight line 512. Connected with. Each bump 503 is connected to the first substrate 501 and the second substrate 502 in a uniform state along the straight line 513.

  In the solid-state imaging device according to the present embodiment, although the curved first and second substrates 501 and 502 are used, a plurality of bumps 503 having the same size can be used for electrical connection between them. .. The bumps 503 connect the first and second substrates 501 and 502 in a uniform state. With this configuration, it is possible to evenly arrange the impedances of the bumps 503 while suppressing the occurrence of the shift of the focal position due to the field curvature by using the curved first and second substrates 501 and 502.

  As described above, according to the present embodiment, it is possible to suppress the occurrence of the shift of the focus position due to the curvature of field, suppress the voltage change of the image pickup signal caused by the different impedance of each bump, and improve the image quality. A highly reliable solid-state imaging device that prevents deterioration is realized.

The preferred embodiments of the present invention have been described above, but the present invention is not limited to these embodiments, and various modifications and changes can be made within the scope of the gist thereof.
For example, as the first substrate which is a solid-state image sensor, a substrate whose first surface is curved so as to have a convex spherical surface is used, and as a second substrate, where the second surface is curved so as to have a concave spherical surface. You may use what was done.

  Although the configuration in which the load current source 203 is arranged in the first substrate 101 has been described with reference to FIGS. 2 and 3, the load current source 203 may be arranged in the second substrate 102. Furthermore, although the configuration in which the DSP 307 is arranged in the second substrate 102 has been described with reference to FIGS. 3 and 4, the DSP 307 can be arranged outside the solid-state imaging device.

101,501 1st substrate 101a, 501a 1st surface 102,502 2nd substrate 102a, 502a 2nd surface 103 bump 111,112,113 curve 200 pixel part 201 vertical scanning circuit 202 vertical output line 203 load current Source 204 Bump pad 300 Photodiode 301 Transfer gate 302 Reset switch 303 Storage capacitance 304 Source follower 305 Row selection switch 306 Readout circuit (AFE)
307 Digital Signal Processing Circuit (DSP)
400 Solid-state image sensor 401 Correlated double sampling circuit (CDS)
402 AD conversion circuits 511, 512, 513 Straight line

Claims (13)

A first substrate which is a solid-state imaging device having a non-planar first surface;
A second substrate having a second surface having a shape different from the first surface;
A plurality of bumps electrically connecting the first substrate and the second substrate,
The plurality of bumps are arranged at positions where the perpendicular lines of the first surface and the second surface overlap each other, between the first surface and the second surface facing each other ,
The first substrate and the second substrate are electrically connected to each other by the plurality of bumps between virtual lines existing on the first surface and the second surface and having the same curvature. The solid-state imaging device is characterized by being. The first surface and the distance between the virtual line existing respectively in said second surface, claim, characterized in that the shortest distance between the second substrate and the first surface 1 The solid-state imaging device according to. The first substrate has a shape in which the first surface is curved in a convex spherical shape,
The second substrate, the solid-state imaging device according to claim 1 or 2, wherein the second surface, characterized in that a curved shape to concave cylindrical surface. The first substrate has a shape in which the first surface is curved into a convex cylindrical surface shape,
The second substrate, the solid-state imaging device according to claim 1 or 2, wherein the second surface, characterized in that a planar shape. A plurality of said bumps, a solid-state imaging device according to any one of claims 1 to 4, characterized in that each of the same size. The first substrate includes a plurality of pixel portions, the bumps and are electrically connected, any claim 1-5, characterized in that a signal line for outputting an image pickup signal of the pixel portion 2. The solid-state imaging device according to item 1. The solid-state imaging device according to claim 6 , wherein the bump is arranged on a line orthogonal to the signal line. The solid-state imaging device according to claim 6, wherein the second substrate includes a circuit that reads out an imaging signal output from the pixel unit through the signal line through the bump. A first substrate, which is a solid-state imaging device having a non-planar first surface, and a second substrate having a second surface having a shape different from the first surface are electrically connected to each other using a plurality of bumps. in the connected,
It said plurality of bumps arranged in each vertical line overlaps the position of the first surface and the second and surface-to-countercurrent Toe Rutotomoni said first surface and said second surface,
Electrically connecting the first substrate and the second substrate between the virtual lines existing on the first surface and the second surface and having the same curvature by the plurality of bumps. A method for manufacturing a solid-state imaging device, comprising: The first surface and the distance between the virtual line existing respectively in said second surface, claim, characterized in that the shortest distance between the first substrate and the second surface 9 A method for manufacturing the solid-state imaging device according to item 1. The first substrate has a shape in which the first surface is curved in a convex spherical shape,
The method for manufacturing a solid-state imaging device according to claim 9 , wherein the second substrate has a shape in which the second surface is curved in a concave cylindrical surface shape. The first substrate has a shape in which the first surface is curved into a convex cylindrical surface shape,
The method for manufacturing a solid-state imaging device according to claim 9 , wherein the second substrate has a planar shape on the second surface. A plurality of said bumps, a method for manufacturing a solid-state imaging device according to any one of claims 9-12, characterized in that each of the same size.

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