JP3959711B2 - Solid-state imaging device and manufacturing method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a solid-state imaging device such as a camera module that mounts a CCD-type imaging device or a CMOS-type imaging device at a high density and a manufacturing method thereof, and more particularly, to a thin solid-state imaging device with little peripheral blur and a manufacturing method thereof.
[0002]
[Prior art]
In recent years, video cameras and electronic cameras have been widely used, and CCD-type and CMOS-type solid-state imaging devices are used for these camera modules.
These solid-state imaging devices are configured by arranging a plurality of unit pixels each provided with a photoelectric conversion means (photodiode; PD) on a thin semiconductor chip in a two-dimensional array to form an imaging region.
In the CCD type solid-state imaging device, light incident on each unit pixel is photoelectrically converted by a photodiode to generate a signal charge, and this signal charge is provided in the output unit via the vertical CCD transfer register and the horizontal CCD transfer register. To the floating diffusion (FD) section. Then, the potential fluctuation of the FD portion is detected by a MOS transistor, converted into an electric signal, and amplified to be output as an imaging signal.
[0003]
On the other hand, in the CMOS type solid-state imaging device, each unit pixel has various MOS transistors such as an FD unit and transfer, amplification, etc., and photoelectrically converts light incident on each unit pixel by a photodiode to generate a signal charge. This signal charge is transferred to the FD portion by the transfer transistor, the potential fluctuation of the FD portion is detected by the amplification transistor, converted into an electric signal, and amplified to output a signal for each pixel from the signal line.
[0004]
FIG. 4 is a configuration diagram showing an arrangement example of the imaging optical system in such a solid-state imaging device.
Reflected light from a subject (not shown) passes through the lens 1 and forms an image on the imaging region of the solid-state imaging device 2.
[0005]
[Problems to be solved by the invention]
Incidentally, with respect to the imaging optical system provided in the solid-state imaging device as described above, lens aberration generally called field curvature occurs.
Therefore, for example, as shown in FIG. 4, even if the in-focus position is set to the light receiving surface A in the center of the imaging region in the solid-state imaging device 2, the focus in the periphery of the imaging region is affected by the above-described curvature of field. Since the position is a position B far from the light receiving surface, defocusing occurs.
As a result, the imaging characteristics have deteriorated, such as non-uniform image quality at the center and periphery of the image.
[0006]
More specifically, when the lens mount is performed so that the light receiving surface A at the center of the imaging region is just focused, the image focused on the point B in the peripheral portion of the imaging region becomes an out-of-focus image.
For this reason, as a lens mounting method, it is necessary to perform a lens mount in which the central focus is slightly defocused to increase the peripheral resolution. For this reason, the overall resolution of the image can be improved relatively, but it is impossible to make the focus from the center to the periphery of the imaging region due to the influence of the aberration of the lens.
In addition to the requirement to reduce the thickness of the module, there is a problem that the lens design becomes more difficult as the thickness is reduced.
[0007]
Accordingly, an object of the present invention is to eliminate the influence of the curvature of field of the imaging optical system, to obtain a high-resolution image without peripheral blur, and to make the camera module and the like thinner and smaller. An object of the present invention is to provide a solid-state imaging device and a method for manufacturing the same.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a thin solid-state imaging device in the form of a semiconductor chip, an adjustment mechanism that adjusts a curvature by bending the solid-state imaging device by applying stress to the solid-state imaging device, Fixing means for fixing the curved state of the solid-state imaging device adjusted by the adjusting mechanism, the adjusting mechanism is provided with a slide substrate portion that can slide on a chip mounting substrate for mounting the solid-state imaging device, The mechanism is configured to apply a stress to the solid-state image sensor to bend by sliding the slide substrate unit in a state where the end of the solid-state image sensor is joined to the slide substrate unit, and the fixing unit includes the adjustment mechanism. And a means for fixing the position of the chip mounting substrate and the slide substrate portion with an adhesive in a state where the solid-state imaging device is curved by the above .
The present invention, when mounting a thin semiconductor chip-like solid-state imaging element chip mounting substrate, by applying a stress to the solid-intends row adjust the curvature by bending the solid-state imaging device adjustment And a fixing step for fixing the adjusted curved state of the solid-state imaging device, the adjustment step includes providing a slide substrate portion that can slide on a chip mounting substrate for mounting the solid-state imaging device, The step of applying a stress to the solid-state imaging device by bending the slide substrate portion with the end portion of the solid-state imaging device being joined to the slide substrate portion, and the fixing step is the adjustment step. It is a step of fixing the position of the chip mounting substrate and the slide substrate portion with an adhesive in a state where the solid-state imaging device is curved by the step .
[0009]
In the solid-state imaging device of the present invention, since the solid-state imaging device in the form of a thin semiconductor chip is curved and fixed at a predetermined curvature by the adjustment mechanism, the entire imaging surface of the solid-state imaging device is focused on the imaging optical system and It can be arranged at an optimum position for the field curvature aberration.
Therefore, it is possible to eliminate the influence of the field curvature of the imaging optical system, obtain an image with high resolution and no peripheral blur, and further reduce the thickness and size of the camera module and the like.
[0010]
In addition, the manufacturing method of the present invention applies stress to the solid-state image pickup device when the thin-film semiconductor chip-like solid-state image pickup device is mounted on the chip mounting substrate, so that the optimal curvature is adjusted and fixed. The entire imaging surface can be disposed at an optimum position with respect to the focal point of the imaging optical system and the field curvature aberration.
Therefore, it is possible to eliminate the influence of the field curvature of the imaging optical system, obtain an image with high resolution and no peripheral blur, and further reduce the thickness and size of the camera module and the like.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of a solid-state imaging device and a manufacturing method thereof according to the present invention will be described below.
The embodiments described below are preferred specific examples of the present invention, and various technically preferable limitations are given. However, the scope of the present invention is not limited to the following description. Unless otherwise specified, the present invention is not limited to these embodiments.
The present embodiment provides a solid-state imaging device that has a function of adjusting a focal point and a field curvature aberration by bending a thin solid-state imaging device (semiconductor chip) by applying stress.
[0012]
Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a plan view showing a chip mounting substrate of the solid-state imaging device according to the first embodiment of the present invention, and FIG. 2 is a cross-sectional view showing an assembly manufacturing process of the solid-state imaging device having the chip mounting substrate shown in FIG. .
In FIG. 1, a chip mounting substrate 10 is slidable in one direction (arrow a direction) with respect to a substrate body 11 constituting a part of the package of the solid-state imaging device (camera module) of this example. And a slide substrate portion 13 provided on the substrate.
In other words, the slide substrate portion 13 is slidably fitted to the slide guide portions 12 provided on both side edges of the substrate body 11.
A light receiving window 14 having a shape substantially corresponding to the imaging area of the solid-state imaging device (semiconductor chip) 15 is formed at the center of the substrate body 11.
[0013]
The solid-state imaging device 15 is mounted on the chip mounting substrate 10 by joining one end portion to the substrate body 11 and the other end portion to the slide substrate portion 13. Then, by sliding the slide substrate portion 13 along the slide guide portion 12, it is possible to apply stress in the direction of arrow a to the solid-state image pickup device 15, and to curve the solid-state image pickup device 15 with an arbitrary curvature.
Note that the substrate main body 11 and the slide substrate unit 13 are equipped with wiring patterns for connecting the electrode pads of the solid-state image sensor 15 and other peripheral circuits, and the solid-state image sensor 15 is electrically connected. Yes. Further, it is assumed that the substrate body 11 and the slide substrate portion 13 are also electrically connected by an electrode pad having a slide structure.
[0014]
Next, a specific assembly operation and structure of the solid-state imaging device according to the present embodiment will be described with reference to FIG.
First, FIG. 2A schematically shows a state in which the solid-state imaging device 15 is bonded to the substrate body 11 and the slide substrate portion 13. In this state, the solid-state imaging device 15 is disposed between the substrate body 11 and the slide substrate unit 13 in a flat state. Note that the imaging surface of the solid-state imaging device 15 faces upward in FIG.
The solid-state imaging device 15 performs back surface grinding on a silicon wafer on which a plurality of solid-state imaging devices are formed, and after thinning the silicon wafer to a predetermined thickness, the wafer is diced to form a plurality of semiconductor chips that respectively constitute the solid-state imaging device. In order to bend easily, it is formed as a very thin flip chip, and is thinned to a thickness of 50 μm, for example. In addition, as a range of the thickness of the solid-state image sensor 15, 20 micrometers-70 micrometers are desirable.
[0015]
Further, both end portions of the solid-state imaging device 15 are electrically and mechanically joined to the chip mounting substrate 10 via the bumps 24 and the underfill material 23. Specifically, Au bumps 24 are formed on the substrate body 11 and the slide substrate portion 13 of the chip mounting substrate 10, and the chip mounting substrate 10 and the solid-state imaging device 15 are bonded by ultrasonic bonding. In addition, as a mounting method in this case, other methods such as a bonding method using an Ag paste and a bonding method using an anisotropic conductive film may be used.
Subsequently, the underfill material 23 is filled in the bump bonding portion to reinforce the bonding strength.
[0016]
Next, as shown in FIG. 2 (B), the slide substrate portion 13 of the chip mounting substrate 10 is slid by applying force from one side (left side in FIG. 2 (B)), and the solid-state imaging device 15 is convex downward. Bend in the shape of
At this time, the chip mounting substrate 10 is electrically connected to an external device for image output, and a slide operation is performed while viewing the image on the monitor of the external device, so that the central portion of the imaging surface and the four corner portions The slide substrate unit 13 is slid to a position where the resolution of the image becomes the maximum, and the slide substrate unit 13 is fixed with an instantaneous adhesive or the like at this position.
The sliding operation is not limited to manual operation, and a predetermined jig can be used. For example, a mechanism that rotates and tightens a screw-like pressing member and presses and slides the slide substrate portion 13 can be provided so that high-precision adjustment can be performed.
Further, instead of confirming the resolution as described above, for example, a pattern in which a black and white vertical line is drawn at a predetermined pitch may be captured, and focus adjustment may be performed while confirming the MTF (Modulation Transfer Function).
[0017]
Next, as shown in FIG. 2C, an adhesive resin 25 is applied and formed as a reinforcement for the solid-state imaging device 15. That is, the adhesive resin 25 is applied so as to surround the entire back surface of the solid-state image pickup device 15 and the main part of the chip mounting substrate 10 in a molten state, and is heated and cured, for example. The position of the slide substrate unit 13 is fixed.
Thereafter, cleaning is performed to remove floating dust and the like attached to the screen (imaging region) of the solid-state imaging device 15, and the sealing glass 26 is bonded to the upper surface of the chip mounting substrate 10 to seal the solid-state imaging device.
The sealing glass 26 can also have an infrared cut filter function. It is also possible to provide a color falsification prevention mechanism using, for example, a diffraction grating.
[0018]
Next, as shown in FIG. 2D, the lens assembly is fixed to the chip mounting substrate 10. At this time, the lens assembly includes a lens barrel portion 28, a lens 27, and a fixed aperture portion 29. The lens barrel part 28 may be an integral part or may be provided with a screw-type mechanism for moving the lens part. Note that the solid-state imaging device 15 may be a single chip including a signal processing circuit and having a function capable of digital output, or the signal processing unit may be independent and a sensor output only device may be used. Good.
Through the above steps, a solid-state imaging device having a curved solid-state imaging element 15 is completed.
In the present embodiment, the solid-state imaging device 15 can be easily fixed to an arbitrary curvature by adjusting the position of the chip mounting substrate 10 having a slide mechanism, and is applied to various imaging optical systems. It is possible.
[0019]
FIG. 3 is a plan view showing a chip mounting board of the solid-state imaging device according to the second embodiment of the present invention. In addition, the same code | symbol is attached | subjected and demonstrated about the same component as 1st Example shown in FIG.
In the first embodiment described above, the slide substrate portion 13 is provided on one side of the solid-state image sensor 15, and the solid-state image sensor 15 is curvedly displaced by sliding it in one direction. However, the second embodiment The slide substrate portions 13A and 13B are provided on both sides of the solid-state image sensor 15, and the solid-state image sensor 15 is curvedly displaced by sliding them in the center direction from both sides.
[0020]
That is, in this embodiment, the substrate body 11 of the chip mounting substrate 10 is provided with slide guide portions 12 on both side edge portions, and the slide guide portion 12 is provided with slide substrate portions 13A and 13B on the left and right sides. . Then, both end portions of the solid-state imaging device 15 are electrically and mechanically joined to the slide substrate portions 13A and 13B. The junction structure is the same as that shown in FIG.
Therefore, the solid-state imaging device 15 is curved to an arbitrary curvature by sliding the one slide substrate portion 13A in one direction (arrow a direction) and the other slide substrate portion 13B in the other direction (arrow b direction). be able to.
Also in the present embodiment, a light receiving window 14 having a shape substantially corresponding to the imaging region of the solid-state imaging device 15 is formed in the central portion of the substrate body 11.
Further, the assembly manufacturing process of the solid-state imaging device according to the present embodiment is substantially the same as the process of the first embodiment described above, but in the process of bending the solid-state imaging device, the left and right slide substrate portions 13A and 13B are moved from both sides. The sliding is performed to adjust the curvature of the solid-state imaging device.
The rest is the same as in the first embodiment, and a description thereof will be omitted.
[0021]
As described above, in the solid-state imaging device according to the present embodiment, the imaging surface of the solid-state imaging device can be curved so as to absorb the field curvature aberration of the lens, and is thin and in focus over the entire area of the screen. A solid-state imaging device can be obtained.
Further, by adjusting the curvature while monitoring, it is possible to manufacture a solid-state imaging device with high accuracy with little individual difference.
In addition, it is possible to mount a solid-state imaging device at an optimal curved position for a lens having a different design, and it becomes possible to manufacture a precise solid-state imaging device that does not depend on the lens design.
The present invention can be applied to either a CCD solid-state image sensor or a CMOS solid-state image sensor.
[0022]
【The invention's effect】
As described above, according to the solid-state imaging device of the present invention, since the solid-state imaging device in the form of a thin semiconductor chip is curved and fixed to a predetermined curvature by the adjustment mechanism, the entire imaging surface of the solid-state imaging device is Since it can be placed at the optimum position for the focal point and field curvature aberration of the imaging optical system, it is possible to eliminate the influence of the field curvature of the imaging optical system and to obtain an image with high resolution and no peripheral blur. In addition, the camera module and the like can be made thinner and smaller. In particular, by adjusting the slide position of the slide substrate portion, the solid-state imaging device can be adjusted to an arbitrary curvature and easily fixed.
[0023]
In addition, according to the manufacturing method of the present invention, when a solid-state image pickup device having a thin semiconductor chip shape is mounted on a chip mounting substrate, stress is applied to the solid-state image pickup device to adjust and fix it to an optimal curvature, so that the solid-state image pickup device is fixed. Since the entire imaging surface of the element can be arranged at an optimum position with respect to the focal point and field curvature aberration of the imaging optical system, the influence of the field curvature of the imaging optical system can be eliminated, and peripheral blurring can be achieved with high resolution. Image can be obtained, and the camera module and the like can be made thinner and smaller. In particular, by adjusting the slide position of the slide substrate portion, the solid-state imaging device can be adjusted to an arbitrary curvature and easily fixed.
[Brief description of the drawings]
FIG. 1 is a plan view showing a chip mounting board of a solid-state imaging device according to a first embodiment of the present invention.
2 is a cross-sectional view showing an assembly manufacturing process of a solid-state imaging device having the chip mounting substrate shown in FIG. 1;
FIG. 3 is a plan view showing a chip mounting board of a solid-state imaging device according to a second embodiment of the present invention.
FIG. 4 is a configuration diagram illustrating an arrangement example of an imaging optical system in a conventional solid-state imaging device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Chip mounting board | substrate, 11 ... Board | substrate body, 12 ... Slide guide part, 13 ... Slide board part, 14 ... Light-receiving window part, 15 ... Solid-state image sensor, 23 ... Underfill material, 24 ...... Bump, 25 ... Adhesive resin, 26 .... Seal glass, 27..Lens, 28..Tube, 29 .. Fixed aperture part.

Claims (11)

A solid-state imaging device in the form of a thin semiconductor chip;
An adjustment mechanism that adjusts a curvature by bending the solid-state image sensor by applying stress to the solid-state image sensor;
Fixing means for fixing the curved state of the solid-state imaging device adjusted by the adjustment mechanism ;
The adjustment mechanism includes a slidable slide substrate portion mounted on a chip mounting substrate for mounting a solid-state image sensor, and slides the slide substrate portion in a state where an end portion of the solid-state image sensor is bonded to the slide substrate portion. By this, it is a mechanism for applying a stress to the solid-state imaging device to bend,
The fixing means is means for fixing the position of the chip mounting substrate and the slide substrate portion with an adhesive in a state where the solid-state imaging device is curved by the adjustment mechanism.
A solid-state imaging device.   The solid-state imaging device according to claim 1, further comprising an image output unit that outputs an image output from the solid-state imaging device to an external device for image monitoring during adjustment by the adjustment mechanism. The solid-state imaging device according to claim 1, wherein the solid-state imaging element is curved in a one-dimensional direction . The solid-state imaging device according to claim 1, wherein the slide substrate portion is provided on one side of the solid-state imaging device. The solid-state imaging device according to claim 1, wherein the slide substrate portion is provided on both sides of the solid-state imaging device. Wherein the fixing means, said after fixing the state of the solid-state image pickup device by an instant adhesive, the solid-state imaging device according to claim 1, characterized in that it comprises an adhesive resin to reinforce the fixed state.   The solid-state imaging device according to claim 1, wherein the solid-state imaging device is a CCD solid-state imaging device. The solid-state imaging device according to claim 1, wherein you, characterized in that the solid-state imaging device is a CMOS type solid-state imaging device. The thin semiconductor chip-like solid-state imaging device in mounting the chip mounting board, the solid stress by adding the image pickup element, and an adjusting step intends line adjustment of curvature by bending the solid-state imaging device, the adjustment A fixing step of fixing the curved state of the solid-state imaging device ,
In the adjusting step, a slide substrate part is provided on a chip mounting substrate for mounting a solid-state image sensor, and the slide substrate part is slid in a state where an end of the solid-state image sensor is joined to the slide substrate part. Is a step of applying stress to the solid-state imaging device to bend it,
The fixing step is a step of fixing the position of the chip mounting substrate and the slide substrate portion with an adhesive in a state where the solid-state imaging device is bent by the adjustment step.
A method of manufacturing a solid-state imaging device. By monitoring the image output from the solid-state imaging device during adjustment of the curvature of the solid-state imaging device by said adjusting step in the external device, according to claim 9, characterized in that to adjust the curvature corresponding to the optimum image The manufacturing method of the solid-state imaging device of description. In the fixing step, the position of the chip mounting substrate and the slide substrate portion is fixed with an adhesive in a state where the solid-state imaging device is bent , and then the fixing state is reinforced with an adhesive resin. A method for manufacturing a solid-state imaging device according to claim 9 .

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