JP2004079578A - Semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve resolution of a solid-state imaging device by solving the field curvature problem and to secure reliability by alleviating strain and stress on peripheral regions. <P>SOLUTION: A substrate 20 for mounting a semiconductor chip 10 having a solid-state imaging device, peripheral circuits, or the like, formed thereon is provided with a sliding mechanism that uses an external force to curve the solid-state imaging device formation region. The sliding mechanism gives stress to and curves the semiconductor chip 10, the curvature rate is then varied and adjusted before the semiconductor chip 10 is fixed at a prescribed position. The sliding mechanism curves only the solid-state imaging device formation region, and other regions outside the solid-state imaging device formation region, such as regions for peripheral circuits or for electrode pads, are left flat without being curved. The design eliminates junction leaks or the like in the peripheral circuit region, and simplifies the processes of flip-flop chip mounting, wire bonding, or the like, because the electrode pad region is flat. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a semiconductor device used for a camera module or the like on which a solid-state imaging device such as a CCD or a CMOS sensor is mounted at a high density, and more particularly to a semiconductor device capable of realizing a thin solid-state imaging device with less peripheral blur.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, there has been provided a solid-state imaging device such as a CCD image sensor or a CMOS image sensor in which a solid-state imaging element formation region and a peripheral circuit region are provided on the same substrate.
Generally, such an imaging optical system of a solid-state imaging device has a problem that lens aberration called field curvature occurs.
FIG. 10 is a diagram for explaining the principle of occurrence of such field curvature, and shows an arrangement state of the solid-state imaging device 1 and the imaging optical system 2.
As shown in the figure, even if the focus position is set to A at the center of the solid-state imaging device 1, the focal position becomes B due to the influence of the curvature of field in the peripheral portion of the imaging device 1. I will.
As a result, the imaging characteristics have deteriorated, for example, the image quality becomes non-uniform between the central portion and the peripheral portion of the image.
[0003]
More specifically, when the lens mount is performed so that the central portion A of the image sensor 1 is in the just focus, the image of the peripheral portion B of the image sensor 1 becomes an out-of-focus image. For this reason, as a method of lens mounting, a lens mount that slightly defocuses the center focus and increases the peripheral resolution is performed.
However, in this case, the overall resolution of the image can be relatively improved, but it is impossible to make the focus from the center to the periphery just because of the aberration of the lens.
In addition to this, there is a problem that the thinner the camera module, the more difficult the lens design becomes in response to a demand to reduce the thickness of the camera module.
[0004]
Therefore, conventionally, for the purpose of solving the above-described problem of the field curvature and simplifying the lens unit, for example, JP-A-10-108078, JP-A-2001-156278, JP-A-2001-284564, and the like. As disclosed in Japanese Patent Application Laid-Open No. H11-260, a technique for bending and mounting the entire semiconductor chip constituting a solid-state imaging device has been proposed.
[0005]
[Problems to be solved by the invention]
However, in the above-described conventional curved mounting technology, since the entire semiconductor chip is mounted in a curved state, surface strain stress is applied to the silicon substrate crystal for all semiconductor circuit elements on the semiconductor chip. For this reason, for example, there is a problem that a surface strain stress acts on a peripheral circuit region irrelevant to the problem of the curvature of field, thereby causing a junction leak on the substrate surface and deteriorating the reliability of the peripheral circuit.
In addition, uniformly bending a semiconductor chip as in the related art is disadvantageous in terms of high-density mounting.
In addition, the electrode pad region for connecting the semiconductor chip to the external circuit is also curved, and there is a problem that the steps of flip-chip mounting and wire bonding for connecting the semiconductor chip and the external circuit are complicated.
[0006]
Therefore, an object of the present invention is to provide a semiconductor device which can solve the problem of field curvature with respect to a solid-state imaging device, can reduce the strain stress applied to the peripheral portion, and can improve the resolution and simplify the lens unit. It is in.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the present invention has a solid state imaging device forming region for imaging a subject by a plurality of photoelectric conversion elements, and a semiconductor chip having a peripheral circuit region formed on the same substrate, wherein the solid state of the semiconductor chip is The imaging element formation region is formed to be curved, and the peripheral circuit region is formed to be flat.
[0008]
Further, according to the present invention, a solid-state imaging device formation region for imaging a subject by a plurality of photoelectric conversion elements, and an electrode pad region for connecting each device of the solid-state imaging device formation region and an external circuit are formed on the same substrate. The semiconductor chip is formed, and the solid-state imaging element formation region of the semiconductor chip is formed to be curved with a predetermined curvature, and the electrode pad region is formed flat.
[0009]
In the semiconductor device of the present invention, only the solid-state imaging element formation region provided on the semiconductor chip is formed to be curved at a predetermined curvature, and the other peripheral circuit regions and electrode pad regions are formed flat. In the area, the field curvature problem can be solved, the strain stress applied to the peripheral part can be reduced, the junction leak problem can be solved, and the connectivity by the electrode pads can be improved. Simplification can be achieved.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of a semiconductor device according to the present invention will be described.
In the present embodiment, in a semiconductor device in which a solid-state imaging device formation region and a peripheral circuit region and an electrode pad region are formed on the same semiconductor chip, only the solid-state imaging device formation region is formed to be curved, and the peripheral circuit region and the The electrode pad region is formed flat.
Specifically, the back surface is ground on the Si wafer on which the solid-state imaging device, peripheral circuits, and the like are formed, and the thickness is reduced to a predetermined thickness. Thereafter, dicing is performed to divide the semiconductor chips into individual semiconductor chips, which are mounted on a mounting substrate. At this time, the mounting substrate is provided with a slide mechanism (stress applying means) that bends the solid-state imaging element formation region by an external force, so that the slide mechanism applies a stress to the semiconductor chip and bends the semiconductor chip. With the curvature adjusted variably, it is fixed at a predetermined position.
In addition, the slide mechanism has a structure in which only the solid-state imaging device formation region is curved, and the peripheral circuit region and the electrode pad region outside the solid-state imaging device formation region bend only the solid-state imaging device formation region while remaining flat. To do.
This eliminates junction leaks and the like in the peripheral circuit region, improves reliability, and simplifies operations such as flip-chip mounting and wire bonding using flat electrode pads.
[0011]
1 to 3 are views showing a configuration example of a camera module on which a semiconductor device according to a first embodiment of the present invention is mounted, and FIG. 1 is a cross-sectional view showing an assembled state of each component of the camera module. FIG. 2 is a plan view showing the arrangement of elements of a semiconductor chip mounted on the camera module, and FIG. 3 is a plan view showing a mounting board provided on the camera module and a slide mechanism thereof.
As shown in FIG. 1, the camera module of the present embodiment includes a semiconductor chip 10, a mounting substrate 20, and a lens unit 30.
As shown in FIG. 2, the semiconductor chip 10 is entirely formed in a rectangular thin plate shape, a solid-state imaging element formation region 11 is formed in a central portion, a peripheral circuit region 12 is formed on both sides thereof, and furthermore, outside thereof. An electrode pad region 13 is formed.
[0012]
In the case of a CCD type sensor, the solid-state imaging element formation area 11 is provided with unit pixels in which photodiodes (photoelectric conversion elements) are arranged in a two-dimensional array, vertical and horizontal transfer registers, and the like. Further, in the case of a CMOS sensor, a two-dimensional array of unit pixels, various signal lines, and the like constituted by a photodiode and various pixel transistors are provided.
Further, the peripheral circuit region 12 is provided with a drive circuit and a signal processing circuit for the solid-state imaging device formation region 11, and various bus lines and the like.
Further, in the electrode pad region 13, a plurality of electrode pads 13A for connecting the semiconductor chip 10 and an external circuit are arranged.
The semiconductor chip 10 may be a device having a function capable of digital output in a single chip including a digital signal processing circuit, or a device having only a sensor output function by making the signal processing circuit independent. May be used.
[0013]
The mounting substrate 20 mounts the semiconductor chip 10 via the Au bumps 14 and the underfill material 15, and includes a substrate main body 21 and a slide substrate 22, as shown in FIG.
The substrate main body 21 has an opening 21A corresponding to the light receiving surface of the solid-state imaging element formation region 11, and slide rails 21B for slidably mounting a slide substrate 22 are provided on both sides of the substrate main body 21. Have been.
The slide substrate 22 is slidably held by a slide rail portion 21B and slides in the direction of arrow A shown in FIG.
[0014]
A circuit wiring pattern (not shown) is formed on the mounting substrate 20, and the electrode pads 13A of the semiconductor chip 10 are connected to the circuit wiring pattern via the Au bumps. In addition, an underfill material 15 is filled in a bonding portion of the electrode pad 13A by the Au bump 14, and the bonding state is reinforced.
Then, in this joined state, the light receiving surface of the solid-state imaging element formation region 11 of the semiconductor chip 10 faces the opening 21A of the mounting substrate 20, and receives light from the lens unit 30 through the opening 21A.
In addition, a seal glass 23 is attached to the opening 21A to prevent ingress of dust and the like.
In addition, the semiconductor chip 10 is fixed in a state where only the solid-state imaging element formation region 11 is curved as shown in FIG. 1 in a state where the camera module is assembled, and the peripheral circuit region 12 and the electrode pad region 13 are flat. It is held in a state, and is surrounded by a mold resin which is omitted in FIG. A method for obtaining such a curved shape will be described later.
[0015]
The lens unit 30 is mounted on the upper surface of the mounting substrate 20, and has a lens barrel 33 provided with a lens barrel 32 provided with a fixed diaphragm 31. Note that the lens barrel 32 may be an integral body, or may be a screw type having a mechanism capable of moving a lens unit.
In such a camera module, light incident through the fixed diaphragm 31 and the lens 33 is received by the solid-state imaging device forming region 11 of the semiconductor chip 10, converted into an image signal by the solid-state imaging device forming region 11, and converted into a peripheral circuit region. The signal is transmitted to the circuit on the mounting substrate side via the electrode pad region 12 and the electrode pad region 13.
[0016]
Next, an assembling process of the above-described camera module and specific examples of each element will be described.
FIG. 4 is a sectional view showing an assembling process of the camera module according to the present embodiment.
First, as shown in FIG. 4A, the semiconductor chip 10 is flip-chip mounted on the mounting substrate 20. At this time, the semiconductor chip 10 is thinned to a thickness of 50 μm to bend. The thickness of the semiconductor chip 10 is desirably in a range of, for example, 20 μm to 70 μm.
In this flip chip mounting step, the Au bumps 14 are formed on the mounting substrate 20 and the mounting substrate 20 and the semiconductor chip 10 are bonded by ultrasonic bonding. The mounting method here may be another method such as bonding using an Ag paste or bonding using an anisotropic conductive film.
Subsequently, the underfill material 15 is filled in the bump joining portion to reinforce the joining strength.
[0017]
Next, as shown in FIG. 4B, a force is applied from one of the substrate body 21 of the mounting substrate 20 and the slide substrate 22 (from the slide substrate 22 side in FIG. 4) to form the solid-state imaging element formation region 11. Are bent in a direction protruding downward. At this time, the mounting substrate 20 is electrically connected to the image drawing board, and the slide substrate 22 is positioned at a position where the resolution at the center and four corners of the screen is maximized while viewing the output image on the monitor for measurement. Is fixed with an instant adhesive or the like.
Here, instead of checking the resolution, a pattern in which black and white vertical lines are drawn at a predetermined pitch may be imaged, and the focus adjustment may be performed while checking the MTF (Modulation Transfer Function).
[0018]
Next, as shown in FIG. 4C, a mold resin 16 is applied and formed as shown in FIG.
Next, cleaning is performed to remove floating dust and the like attached to the solid-state imaging device formation region 11 and the like, the seal glass 23 is bonded to the mounting substrate 20, and the solid-state imaging device formation region 11 is sealed. The seal glass 23 may have an infrared cut filter function. Further, for example, a color false prevention mechanism using a diffraction grating can be provided.
Next, as shown in FIG. 4D, the lens unit 30 is fixed to the mounting substrate 20.
[0019]
Through the steps described above, a semiconductor device having a curved solid-state imaging element formation region is completed.
In the present embodiment, it is possible to arbitrarily change the curvature of the light receiving surface of the solid-state imaging element formation region by adjusting the position of the mounting substrate 20 having the slide mechanism, and to apply the present invention to various types of lenses. Is possible.
Then, by bending only the solid-state imaging element formation region, a flat silicon substrate free from strain stress can be used in a peripheral circuit region where minute leakage is a problem, and the reliability of the circuit can be improved.
Furthermore, by using a flat substrate surface for the pad region, the same method as in the past can be used for flip chip mounting itself, and simplification of the manufacturing operation can be obtained. In other words, it is not necessary to make the mating substrate on which the semiconductor chip is flip-chip mounted a highly accurate curved surface, and it is possible to avoid complication.
This has the same effect in wire bonding. That is, there is an advantage that wire bonding may be performed on a flat chip portion similar to the conventional one, and it is not necessary to perform wire bonding on an unstable curved surface.
[0020]
FIG. 5 is a diagram showing a configuration example of a camera module on which a semiconductor device according to a second embodiment of the present invention is mounted, and is a plan view showing a mounting board provided in the camera module and a slide mechanism thereof. Since the configurations of the semiconductor chip and the lens unit are common to those of the first embodiment, the drawings are omitted and the description will be made using the same reference numerals.
This example is a configuration example in the case where the slide substrate is slid from both sides of the semiconductor chip 10 and mounted in a curved manner. That is, the mounting board 40 of the present example is provided with a pair of slide boards 42 and 43 for pressing the semiconductor chip 10 from the left and right sides of the board body 41 on the board body 41 by the slide rail portions 41B provided on the upper and lower sides of the mounting board 40. It is slidably provided.
When the semiconductor chip 10 is mounted in a curved manner, the slide substrates 42 and 43 on both sides are slid in the directions of arrows A and B, and the solid-state imaging element formation region 11 of the semiconductor chip 10 is curved with a desired curvature.
The opening 41A formed in the substrate main body 41 is the same as the above-described opening 21A.
The camera module assembling / manufacturing process is the same as that of the first embodiment shown in FIG. 4 except for the method of bending the semiconductor chip.
[0021]
Next, a method for bending only the solid-state imaging element formation region 11 of the semiconductor chip 10 in the first and second embodiments as described above will be described.
First, as a first method, the peripheral circuit region 12 and the pad region 13 of the semiconductor chip 10 are firmly joined to the mounting substrate 20 or the mounting substrate 40 and reinforced so that their flatness is not impaired. In this state, by moving the slide substrate 22 or the slide substrates 42 and 43, only the solid-state imaging element formation region 11 can be curved.
At this time, a desired bending state can be easily obtained by appropriately selecting the bonding strength between the peripheral circuit region 12 and the pad region 13 of the semiconductor chip 10 and the mounting substrates 20 and 40, and the thickness of the semiconductor chip 10. Becomes possible.
[0022]
As a second method, it is possible to perform suction mounting by a curved type.
FIG. 6 is a cross-sectional view showing a specific example of the bending type and the mounting operation in this case.
As shown in the drawing, the curved mold 50 has an arc-shaped concave portion 51 corresponding to the curved shape of the solid-state imaging device forming region 11 of the semiconductor chip 10 and a flat surface for holding the peripheral circuit region 12 and the pad region 13 flat. A portion 52 is formed, and a plurality of suction holes 53 for vacuum-sucking the semiconductor chip 10 are formed in a distributed manner from the concave portion 51 to the flat portion 52.
In such a curved mold 50, vacuum suction is performed by the suction holes 53 in a state where the concave portion 51 and the flat portion 52 are in contact with the semiconductor chip 10, and only the solid-state imaging element formation region 11 is curved into a desired curved shape. be able to.
In addition, it is possible to slide the slide substrate 22 or 42 or 43 described above in synchronization with the bending deformation at this time, and to follow the deformation of the semiconductor chip 10.
In addition, operations such as fixing after bending are the same as described above, and a description thereof will be omitted.
[0023]
7 and 8 are views showing a configuration example of a camera module on which a semiconductor device according to a third embodiment of the present invention is mounted, and FIG. 7 is a cross-sectional view showing an assembled state of each component of the camera module. FIG. 8 is a plan view showing the arrangement of each element of a semiconductor chip mounted on a camera module.
In the semiconductor chip 60 of this example, a solid-state imaging element formation region 61 is provided in the center portion, a pad region 62 is provided on a side portion thereof, and a peripheral circuit region 63 is provided outside the pad region 62.
In this example, the outer edge portion 64 of the semiconductor chip 60 where the peripheral circuit region 63 is provided is bent 90 ° in the back direction to form a module reduced in the width direction. Since the bent portion of the semiconductor chip 60 is flat, the surface strain stress in the peripheral circuit region 63 is small, and the problem of junction leakage does not occur.
Although the dimensions of other mounting substrates and lens units are changed, the basic principles are the same as those of the first and second embodiments described above. Omitted.
[0024]
FIG. 9 is a cross-sectional view showing a curved die and a specific example of a mounting operation when the semiconductor chip according to the third embodiment is bent and mounted.
As shown in the figure, the curved mold 70 includes an arc-shaped concave portion 71 corresponding to the curved shape of the solid-state imaging element forming region 61 of the semiconductor chip 60, an edge portion 72 receiving the pad region 62, and a peripheral circuit region 63. And a vertical flat portion 73 for holding flat in a bent state.
A plurality of suction holes 74 for vacuum-suctioning the semiconductor chip 10 are formed in the concave portion 71 and the vertical flat portion 73 in a dispersed manner.
With such a curved mold 70, the solid-state imaging element forming area 61 of the semiconductor chip 60 is suction-curved in an arc shape, and the peripheral circuit area 63 is shaped into a 90-degree bent state. Can be obtained.
The 90 ° bending process of the peripheral circuit region 63 can be realized not only by vacuum suction but also by a process of mechanically bending in advance. In addition, the specific shape of the curved type is not limited to the illustrated one, and various modifications are possible.
For example, the curved shape may be either a semi-cylindrical shape or a spherical shape, and the curved surface may not be an ideal curved surface having a constant curvature.
[0025]
As described above, according to each of the embodiments of the present invention, the light receiving surface of the solid-state imaging device can be curved so as to absorb the field curvature aberration of the lens. A semiconductor device mounted with a solid-state imaging device that is in focus over the region can be obtained.
In addition, the curvature of the solid-state imaging element formation region can be adjusted while monitoring the output image, and a highly accurate method with a small difference between individuals can be realized.
In addition, it is possible to mount the solid-state imaging device at an optimal curved position on a lens having a different design, and it is possible to manufacture a precise solid-state imaging device that does not depend on the lens design.
Further, it is possible to incorporate a part of the semiconductor chip into the camera module in a bent state, which can contribute to downsizing of the solid-state imaging device and the camera module.
[0026]
In the above embodiment, the case where the solid-state imaging device formation region, the peripheral circuit region, and the pad region are provided on the same chip has been described, but the solid-state imaging device formation region and the peripheral circuit region are provided on the same chip. Alternatively, the present invention can be similarly applied to an element having a solid-state imaging element formation region and a pad region on the same chip.
Further, as the image pickup device applied to the present invention, it is possible to apply the image pickup device to various types such as a CCD type and a CMOS type.
[0027]
【The invention's effect】
As described above, according to the semiconductor device of the present invention, only the solid-state imaging element forming region provided in the semiconductor chip is formed by bending to a predetermined curvature, and other peripheral circuit regions and electrode pad regions are formed flat. Therefore, for the solid-state imaging element formation region, the problem of field curvature can be solved, the strain stress applied to the peripheral portion can be reduced, the problem of junction leakage can be solved, and the connectivity by the electrode pads can be improved, and the This has the effect of improving the resolution and simplifying the lens unit.
[Brief description of the drawings]
FIG. 1 is a sectional view showing an assembled state of components of a camera module on which a semiconductor device according to a first embodiment of the present invention is mounted.
FIG. 2 is a plan view showing an arrangement of each element of a semiconductor chip mounted on the camera module shown in FIG. 1;
FIG. 3 is a plan view showing a mounting board provided in the camera module shown in FIG. 1 and a slide mechanism thereof.
FIG. 4 is a sectional view showing an assembling step of the camera module shown in FIG. 1;
FIG. 5 is a plan view showing a mounting board provided in a camera module on which a semiconductor device according to a second embodiment of the present invention is mounted and a slide mechanism thereof.
FIG. 6 is a cross-sectional view showing a specific example of a curved die used for the semiconductor chip shown in FIGS. 1 and 5 and a mounting operation.
FIG. 7 is a cross-sectional view illustrating an assembled state of components of a camera module equipped with a semiconductor device according to a third embodiment of the present invention.
8 is a plan view showing an arrangement of each element of a semiconductor chip mounted on the camera module shown in FIG. 7;
FIG. 9 is a cross-sectional view showing a specific example of a curved die used for the semiconductor chip shown in FIG. 7 and a mounting operation.
FIG. 10 is a side view illustrating the principle of occurrence of curvature of field that occurs in a conventional solid-state imaging device.
[Explanation of symbols]
Reference numeral 10: semiconductor chip, 11: solid-state imaging element formation region, 12: peripheral circuit region, 13: electrode pad region, 20: mounting substrate, 21: substrate body, 21A: opening, 21B ... ... Slide rail part, 22 ... Slide board, 23 ... Seal glass, 30 ... Lens unit, 31 ... Fixed aperture, 32 ... Barrel, 33 ... Lens.

Claims (8)

A solid-state imaging element forming region for imaging a subject by a plurality of photoelectric conversion elements, and a semiconductor chip having a peripheral circuit region formed on the same substrate;
The solid-state imaging element forming region of the semiconductor chip is formed to be curved, and the peripheral circuit region is formed to be flat,
A semiconductor device characterized by the above-mentioned. 2. The semiconductor device according to claim 1, wherein the peripheral circuit region includes at least one of a driving circuit and a signal processing circuit of each element in the solid-state imaging device formation region. The semiconductor chip has an electrode pad region formed on the same substrate as the solid-state imaging device formation region and for connecting each element of the solid-state imaging device formation region to an external circuit,
2. The semiconductor device according to claim 1, wherein an electrode pad region of said semiconductor chip is formed flat. The solid-state imaging device forming region is curved by applying a stress in a substrate surface direction of the semiconductor chip by a stress applying unit provided on the mounting substrate, the mounting substrate having the mounting substrate on which the semiconductor chip is mounted. The semiconductor device according to claim 1, wherein 2. The semiconductor device according to claim 1, wherein a portion where the peripheral circuit region of the semiconductor chip is provided is bent in a direction toward a back surface of the semiconductor chip with respect to a portion where the solid-state imaging device formation region is provided. A semiconductor chip in which a solid-state imaging element forming area for imaging a subject by a plurality of photoelectric conversion elements and an electrode pad area for connecting each element of the solid-state imaging element forming area and an external circuit are formed on the same substrate. Have
The solid-state imaging element forming region of the semiconductor chip is formed to be curved at a predetermined curvature, and the electrode pad region is formed flat.
A semiconductor device characterized by the above-mentioned. The solid-state imaging device forming region is curved by applying a stress in a substrate surface direction of the semiconductor chip by a stress applying unit provided on the mounting substrate, the mounting substrate having the mounting substrate on which the semiconductor chip is mounted. 6. The semiconductor device according to claim 5, wherein: 8. The semiconductor device according to claim 7, wherein said semiconductor chip is connected to circuit wiring provided on said mounting substrate via said electrode pad region.

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