JP2017084874A - Solid state image pickup device and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent degradation in image quality by suppressing voltage changes in pick-up signal caused from variation of impedance at each bump.SOLUTION: The solid state image pickup device includes: a first substrate 101 as a solid state image pick-up device which has a first surface 101a having a non-planar shape; a second substrate 102 which has a second surface 102a different from that of the first surface 101a; and a bump 103 which electrically connects the first substrate 101 to the second substrate 102. The bump 103 is disposed at a position between opposing first surface 101a and second surface 102a and respective perpendicular lines of the first surface 101a and the second surface 102a are overlapped with each other.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a solid-state imaging device and a manufacturing method thereof.

  2. Description of the Related Art Conventionally, some imaging devices such as digital still cameras and digital video cameras have a CMOS image sensor mounted as a solid-state imaging device. These solid-state imaging devices have an imaging surface composed of a pixel portion including a photoelectric conversion device. A lens is used for the purpose of imaging a subject on the imaging surface. In general, when a subject is imaged by a lens, the focal position shifts between the central portion and the peripheral portion of the imaging surface due to curvature of field. In order to solve this problem, a technique for bending the solid-state imaging device itself has been proposed (see Patent Document 1).

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

JP 2008-294960 A JP 2009-049499 A

  However, in the technique described in Patent Document 2, the use of a plurality of bumps having different sizes in the thickness direction in order to connect the solid-state imaging device and the signal processing board may result in different impedances of the bumps. Concerned. As a result, the voltage of the imaging signal from the solid-state imaging device may change, and a signal different from the original voltage level may be input to the substrate, which may cause image quality degradation.

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

  The solid-state imaging device of the present invention includes a first substrate that is a solid-state imaging device having a first surface having a non-planar shape, a second substrate having a second surface having a shape different from the first surface, Bumps for electrically connecting the first substrate and the second substrate, the bumps between the first surface and the second surface facing each other, the first surface And the perpendiculars of the second surface and the second surface are arranged at positions where they overlap.

  The method for manufacturing a solid-state imaging device according to the present invention includes a first substrate that is a solid-state imaging device having a first surface having a non-planar shape, and a second surface having a second surface having a shape different from the first surface. When connecting the substrate to the substrate using bumps, the first surface and the second surface are sandwiched between the first surface and the second surface at positions where the perpendiculars of the first surface and the second surface overlap each other. Opposing and connecting by the bumps.

  According to the present invention, it is possible to suppress the occurrence of a focal position shift due to the curvature of field and the like, and to suppress the voltage change of the imaging signal that occurs due to the different impedances of the bumps, thereby preventing image quality deterioration. 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 the schematic which shows the structure of the 1st board | substrate of the solid-state imaging device in 1st Embodiment. FIG. 3 is an equivalent circuit diagram illustrating configurations of a first substrate and a second substrate of the solid-state imaging device according to the first embodiment. It is a block diagram which shows the structure of the 2nd board | substrate of the solid-state imaging device in 1st Embodiment, and the relationship between the pixel part of a 1st board | substrate, and a 2nd board | 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)
FIGS. 1A and 1B are schematic views illustrating the appearance of the solid-state imaging device according to the first embodiment, in which FIG. 1A is a perspective view and FIG. 1B is a cross-sectional view along a broken line (curve 113).
The 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. Configured. The first substrate 101 and the second substrate 102 are laminated with the first and second surfaces 101a and 102a facing each other and bonded.

The first substrate 101 is a solid-state imaging device, is curved so that the first surface 101a has a convex spherical shape, and a plurality of pixel portions including photoelectric conversion elements are two-dimensionally arranged in the row direction and the column direction. Has been. The curved shape of the first substrate 101 is a shape that is optically appropriate 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 for joining the first surface 101a and the second surface 102a. Virtual lines (curves 111, 112) having the same curvature exist on the first surface 101a and the second surface 102a, respectively. On the curves 111 and 112, the 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 perpendiculars 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 passing through the centers of the plurality of bumps 103 and 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 the same. Therefore, the bumps 103 having the same size can be used.

Hereinafter, a method for connecting the first substrate 101 and the second substrate 102 when manufacturing the solid-state imaging device of the present embodiment will be described.
The first substrate 101 and the second substrate 102, the first surface 101a and the second surface 102a, and the positions where the perpendiculars of the first surface 101a and the second surface 102a overlap (curves 111, 112 at positions facing each other in parallel) with the bumps 103 therebetween. Between the first substrate 101 and the second substrate 102, a plurality of bumps 103 having the same size are arranged along a curve 113. 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, and the distance is kept constant along the curves 111 and 112 even if the distance between the two is shortened by the pressure bonding. Be drunk. Accordingly, even when 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. Connected to the pad 204. Each bump 103 is connected to the first substrate 101 and the second substrate 102 along a curved line 113 in a uniform state.

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

FIG. 3 is an equivalent circuit diagram illustrating configurations of the first substrate and the second substrate of the solid-state imaging device according to the first embodiment.
The pixel portion 200 that is a constituent element 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 functioning as a photoelectric conversion element generates and accumulates signal charges corresponding to the irradiated light. The transfer gate 301 is ON / OFF controlled by the signal φTXn, and transfers the signal charge generated and stored 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 accumulated 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 constitute a floating diffusion amplifier. The row selection switch 305 is controlled to be 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 reading circuit (AFE) 306, a digital signal processing circuit (DSP) 307, and a bump pad 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. An imaging signal output from the first substrate 101 via the bump 103 is input to the second substrate 102 from the bump pad 204 disposed on the second substrate 102. A detailed description of the second substrate 102 will be described later.

  FIG. 4 is a block diagram illustrating 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, only one pixel portion 200 of the first substrate 101 is shown for convenience.

  The solid-state imaging device 400 according to the present embodiment includes a first substrate 101 and a second substrate 102. As described above, in the first substrate 101, the pixel unit 200 converts light into an imaging signal and outputs it to the bump 103. The imaging 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 kinds 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 imaging device 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. . Each bump 103 connects the first and second substrates 101 and 102 in a uniform state. With this configuration, even if the curved first and second substrates 101 and 102 are used to suppress the occurrence of focal position shift due to field curvature, 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 a focal position shift due to the curvature of field and the like, and also to suppress the voltage change of the imaging signal that occurs due to the impedance of each bump being different. A highly reliable solid-state imaging device that prevents deterioration is realized.

(Second Embodiment)
FIGS. 5A and 5B are schematic diagrams illustrating the appearance of the solid-state imaging device according to the second embodiment, in which FIG. 5A is a perspective view and FIG.
In this solid-state imaging device, a first substrate 501 having a first surface 501a having a non-planar shape and a second substrate 502 having a second surface 502a having a planar shape are first and second surfaces 501a. , 502a are joined to face each other.

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

  The first substrate 501 and the second substrate 502 are electrically connected by bumps 503 such as solder for joining the first surface 501a and the second surface 502a. Virtual straight lines 511 and 512 exist on the first surface 501a and the second surface 502a, respectively. On the straight lines 511 and 512, the perpendicular lines 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 normal lines 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 the same. Therefore, the bumps 503 having the same size can be used.

Hereinafter, a method of connecting the first substrate 501 and the second substrate 502 when manufacturing the solid-state imaging device of the present embodiment will be described.
The bumps 503 are formed at a position where the perpendiculars of the first surface 501a and the second surface 502a overlap each other (a position where the straight lines 511 and 512 face each other in parallel). Opposite it across. 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 bonded to each other. 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 the distance is kept constant along the straight lines 511 and 512 even if the distance between the two is shortened by pressure bonding. Be drunk. Therefore, even when 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. Each bump 503 is connected to the first substrate 501 and the second substrate 502 along a straight line 513 in a uniform state.

  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 therebetween. . Each bump 503 connects the first and second substrates 501 and 502 in a uniform state. With this configuration, even if the curved first and second substrates 501 and 502 are used to suppress the occurrence of a focal position shift due to field curvature, the impedance of each bump 503 can be made uniform.

  As described above, according to the present embodiment, it is possible to suppress the occurrence of a focal position shift due to the curvature of field and the like, and also to suppress the voltage change of the imaging signal that occurs due to the impedance of each bump being different. A highly reliable solid-state imaging device that prevents deterioration is realized.

As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to these embodiment, A various deformation | transformation and change are possible within the range of the summary.
For example, a first substrate that is a solid-state imaging device is a substrate that is curved so that the first surface has a convex spherical shape, and a second substrate that is curved so that the second surface has a concave spherical shape. You may use what you did.

  2 and 3, the configuration in which the load current source 203 is disposed in the first substrate 101 has been described. However, a configuration in which the load current source 203 is disposed in the second substrate 102 may be employed. Further, in FIG. 3 and FIG. 4, the configuration in which the DSP 307 is arranged in the second substrate 102 has been described, but the DSP 307 can also be arranged outside the solid-state imaging device.

101, 501 First substrate 101a, 501a First surface 102, 502 Second substrate 102a, 502a Second surface 103 Bump 111, 112, 113 Curve 200 Pixel unit 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 capacitor 304 Source follower 305 Row selection switch 306 Read circuit (AFE)
307 Digital signal processing circuit (DSP)
400 Solid-state image sensor 401 Correlated double sampling circuit (CDS)
402 AD conversion circuit 511, 512, 513 Straight line

Claims (15)

A first substrate that is a solid-state imaging device having a non-planar first surface;
A second substrate having a second surface different in shape from the first surface;
A bump for electrically connecting the first substrate and the second substrate;
The bump is arranged between the first surface and the second surface facing each other at a position where the perpendicular lines of the first surface and the second surface overlap each other. Solid-state imaging device.   2. The virtual line having the same curvature exists on each of the first surface and the second surface, and a plurality of the bumps are connected between the lines. Solid-state imaging device.   3. The solid-state imaging device according to claim 2, wherein a distance between each of the lines is a shortest distance between the first surface and the second substrate. The first substrate has a shape in which the first surface is curved into a convex spherical shape,
The solid-state imaging device according to claim 1, 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 spherical shape,
The solid-state imaging device according to claim 1, wherein the second substrate has a planar shape on the second surface.   The solid-state imaging device according to claim 1, wherein the plurality of bumps have the same size.   7. The first substrate according to claim 1, further comprising: a plurality of pixel units; and a signal line that is electrically connected to the bumps and outputs an imaging signal of the pixel units. The solid-state imaging device according to claim 1.   The solid-state imaging device according to claim 7, wherein the bump is disposed on a line orthogonal to the signal line.   9. The solid according to claim 1, wherein the second substrate has a circuit that reads out an imaging signal output from the pixel unit through the signal line through the bump. 10. Imaging device. When connecting 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 using bumps ,
The first surface and the second surface are opposed to each other across the bump at a position where the perpendicular lines of the first surface and the second surface overlap, and are connected by the bump. Manufacturing method of a solid-state imaging device.   11. The solid according to claim 10, wherein a virtual line having the same curvature exists on each of the first surface and the second surface, and a plurality of the bumps are connected between the lines. Manufacturing method of imaging apparatus.   The method for manufacturing a solid-state imaging device according to claim 11, wherein the distance between the lines is the shortest distance between the first surface and the second substrate. The first substrate has a shape in which the first surface is curved into a convex spherical shape,
13. The method of manufacturing a solid-state imaging device according to claim 10, wherein the second substrate has a shape in which the second surface is curved into a concave cylindrical surface. The first substrate has a shape in which the first surface is curved into a convex spherical shape,
The method for manufacturing a solid-state imaging device according to claim 10, wherein the second substrate has a planar shape on the second surface.   The method for manufacturing a solid-state imaging device according to claim 10, wherein the plurality of bumps have the same size.

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