JPH09232551A - Photoelectric conversion device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve mechanical strength of an anisotropic conductive paste, a conductive paste and a package and prevent generation of a defective image, by changing the layout of microlenses formed on a color filter and partly removing a microlens array. SOLUTION: A part of microlenses 5b which are located outside an image area 3c of a CCD chip 3 are removed in such a manner as to surround the image area 3c, thus forming a lens removed portion 11. A color filer 5a and the microlenses 5b located outside the image area 3c are provided for the purpose of maintaining manufacturing stability. Therefore, partly removing the microlenses causes no problem in characteristics. Since an anisotropic conductive paste 4 which is to enter the CCD chip has its diffusion direction dispersed to the outer periphery of the image area on the microlenses 5b intermittently formed before the image area, the quantity of the anisotropic conductive paste entering the image area 3c may be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photoelectric conversion device using a CCD (solid-state image sensor).

[0002]

2. Description of the Related Art Electronic parts in which electric elements are housed in a small package are widely used for industrial purposes. Above all, CC
D has a wide range of applications such as cameras. Such a CCD is
The demand for miniaturization is particularly strong for industrial use, and each company is struggling to develop light, thin, short, and small products. Regarding the mounting method of this CCD, JP-A-7-099214 and JP-A-7-153796 are known.

A conventional photoelectric conversion device will be described below with reference to the drawings. FIG. 9 shows the members constituting the package and the manufacturing process. It is composed of a wiring board 1, an optical glass 2, and a CCD chip 3. First, FIG. 9 (a)
Then, the optical glass 2 and the wiring board 1 are bonded. The wiring board 1 is composed of an insulating base material 1a and an electrode pattern 1b, and has a central opening 1c. The adhesive is applied to the back surface of the insulating base material 1a using, for example, an ultraviolet curable adhesive. Next, in FIG. 9B, an anisotropic conductive paste 4 and a conductive adhesive are formed around the electrode pattern 1b. In FIG. 9C, the CCD chip 3 is electrically connected to the electrode pattern 1b by thermocompression bonding from above the anisotropic conductive paste 4.

FIG. 10 is a sectional view showing a completed package. At this time, the inside of the package corresponding to the pixels of the CCD chip 3 has a hollow structure (cavity p).
The structure is such that the condensing effect of the microlens 5 formed on the surface of the CCD chip 3 is utilized.

Further, the anisotropic conductive paste 4 is completely filled between the CCD chip 3 and the wiring substrate 1, and CC
The entire outer periphery of the D chip 3 is shielded from the outside air, that is, a hermetically sealed structure is achieved.

With the structure described above, it is possible to obtain a CCD package which can be miniaturized by a simple manufacturing process.

By the way, as shown in FIG. 11A, bonding pads 3a are formed on both sides of the surface of the CCD chip 3, and a color filter 5 is formed in the photoelectric conversion portion.
There is an area 3b for forming a and a microlens 5b. The color filter 5a has four layers of complementary colors of cyan, magenta, and yellow and has a thickness of about 5 μm.
a has a diameter of 2 μm to 3 μm and a height of 1.5 μm to 2.0 μm
It is. Both of them are made of acrylic resin. Further, in order to secure the manufacturing clearance, as shown in FIG. 11B, the color filter 5a is attached to the image area 3c.
And the formation of microlens 5b Area 3b is 50 μm
It is designed to be about 200 μm larger.

Here, the problems in the current mounting method will be described with reference to FIG. In FIG. 12 (a), the CCD
When the chip 3 and the wiring board 1 are bonded via the anisotropic conductive paste 4, a part of the anisotropic conductive paste 4 is CC
Intruding into the image area 3c of the D chip 3,
As shown in (b), bleeding defect (image defect) E of the anisotropic conductive paste 4 occurs. Since the anisotropic conductive paste 4 is a viscous paste, some components of the anisotropic conductive paste 4 flow out onto the color filter 5a and the microlens 5b of the CCD chip 3 when thermocompression bonding is performed. It is a phenomenon of bleeding. Hereinafter, this defect is called "bleeding defect"
That.

As a result of investigating this "bleeding defect", 1 μm formed between microlenses on adjacent hemispheres.
The anisotropic conductive paste of the same as above penetrates into the gap of about a certain degree, and the low-viscosity component in the anisotropic conductive paste 4 becomes
It is presumed that "blurring failure" occurs due to the capillary invasion into c.

Normally, the wiring board is designed with a margin that does not penetrate into the image area 3c. However, the "bleeding failure" may occur due to the lot variation of the anisotropic conductive paste 4 and the change in the posting of the viscosity. Was.

According to the results of further experiments, it is found that the anisotropic conductive paste 4 on the CCD chip 3 accelerates the seepage of the anisotropic conductive paste 4 from the color filter 5a layer to the microlens 5b forming layer. ing.

Exudation when the space margin SM of the microlenses outside the image area is narrowed will be described with reference to FIG. The distance L from the bonding pad 3a to the image area 3c is about 100 μm. The anisotropic conductive paste 4 is applied for chip bonding, and a part of the anisotropic conductive paste 4 is applied to the image area 3c.
Invade towards. The penetration direction of the anisotropic conductive paste 4 starts from F, and the image area 3 moves in the D and E directions.
It spreads on the fan in c. F is the diffusion on the color filter 5a, and the diffusion speed at this time is VF0, which is relatively low. Further, when the anisotropic conductive paste comes into contact with the microlenses, the diffusion action is accelerated in the valley between the adjacent microlenses by a capillary phenomenon, and the diffusion speed of VF0 becomes equal to that of VD0 and VE0 in D and E, respectively. Change. The diffusion speeds VD0 and VE0 are several times faster than the diffusion speed VF0. The difference in diffusion speed is about 10 times. Therefore, it takes less time to reach the inside of the image area before the anisotropic conductive paste is heated and hardened.

Therefore, the same applicant proposes, in Japanese Patent Application No. 7-155865, a structure in which the microlens 5b is arranged inside the opening 1c of the wiring board 1 with respect to the formation position of the microlens 5b.

This is as shown in FIG.
It was found that the microlens 5b including the color filter 5a is arranged on the inner side of the end portion of 1., whereby the oozing defect of the anisotropic conductive paste 4 can be dramatically avoided.

However, this defect cannot be completely avoided, and further preventive measures have been demanded. Also,
In the current method of FIG. 14, from the formation end of the color filter 5a and the microlens 5b to the bonding pad 3a, 1
It is necessary to set a large distance of about 00 μm to 200 μm, and there is a limit to miniaturization of the CCD chip 3.

Further, as a modification, the same applicant previously applied for "dam frame formation" for preventing the seepage of the anisotropic conductive paste 4. This is shown in FIG.
As shown in (b), the bonding pad 3 on at least one of the CCD chip 3 and the wiring substrate 1.
It is a means for forming dam frames 6a and 6b between a and the image area 3c. The main purpose of this is to provide a bank which is structurally thicker than the film thickness of the anisotropic conductive paste 4. As a result, the effect of preventing the anisotropic conductive paste 4 from penetrating into the image area 3c beyond the dam frame and causing an image defect can be expected.

However, in the dam frame forming technique of FIG. 15, it is necessary to add another material and another process, which makes the formation extremely complicated. The formation of the dam frames 6a and 6b is
A few tens of μ formed with a very small width such as a photoresist formation method
A formation space of about m to 100 μm is required, and an increase in chip size including the formation width makes it extremely difficult to reduce the device size. Furthermore, it may affect the face-down mounting by bump connection described above. Therefore, it is important to control the height of the dam frame, but it is extremely difficult to control the height of the bump and the height of the dam frame, and there is a concern that the reliability of the connection may be deteriorated.

[0018]

In the above-mentioned conventional photoelectric conversion device, from the formation end of the filter and the microlens,
In the case of the method of increasing the distance to the bonding pad, it is necessary to increase this distance, which limits the miniaturization of the CCD chip. Further, when the dam frame is provided, it is extremely difficult to control the height of the bump and the height of the dam frame, which may cause a decrease in reliability of connection.

According to the present invention, the anisotropic conductive paste and the conductive paste, and further the resin sealant for improving the mechanical strength and the sealing property of the package, flow into the image area to prevent image defects. Provide a strategy.

[0020]

In order to solve the above-mentioned problems, in the photoelectric conversion device of the present invention, the arrangement structure of the microlenses formed on the color filter is changed to remove some microlens rows. It was done.

As a result, the anisotropic conductive paste, which is about to enter the CCD chip, is dispersed in the diffusion direction around the outer periphery of the image area on the microlens formed by dividing in front of the image area. The amount of diffusion that enters the image area can be reduced.

[0022]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is an explanatory diagram for explaining a first embodiment of the present invention. The same components as those of this embodiment will be described with the same reference numerals. FIG. 1A shows the CCD chip 3.
1B is a front view for explaining the arrangement of the microlenses 5b arranged on the color filter 5a of FIG.
FIG. 4A is a cross-sectional view for explaining a state in which the CCD chip 3 and the wiring substrate 1 in the AA ′ cross section of (a) are electrically connected via the anisotropic conductive paste 4.

That is, this embodiment is shown in FIG.
As shown in FIG. 3, a part of the microlens 5b arranged outside the image area 3c of the CCD chip 3 is removed so as to surround the image area 3c, and the lens removing unit 11
Is formed. At this time, the distance between the bonding pad 3a and the microlens 5b is set to be narrower than the distance in the conventional case.

By the way, the color filters 5a and the microlenses 5b outside the image area 3c are provided for stability in manufacturing. Therefore, even if a part is removed, there is no problem in characteristics.

An example of forming the lens removing portion 11 will be further described with reference to FIG. The dummy lens formation area 31, which is the portion where the microlens 5 is formed outside the image area 3c, requires about 50 μm, and the number of pixels is 6 to 10 pixels. The lens removing unit 11 in this embodiment is
1 to 3 columns of the dummy lens formation region 31 are removed, that is, the removal width of 1 to 3 pixels is set to about 5 to 20 μm.

Next, the operation of the lens removing section 11 will be described with reference to FIG. The CCD chip 3 has a size of 2 m.
Extremely small CC with m-square and 10 to 150,000 pixels
A D chip is assumed. The microlens 5b is shown in FIG.
As shown in (a), it is formed close to the bonding pad 3a. Therefore, as shown in FIG. 3B, the anisotropic conductive paste 4 reaches the microlenses 5b that are separated and formed in an island shape outside the image area 3c through the lens removing portion 11 in a short time. Will be things.

However, after reaching the microlens 5b, the speed VD0 at which most of the anisotropic conductive paste 4 diffuses in the direction D in the figure along the outer peripheral portion of the image area 3c.
The diffusion speed VF1 penetrating in the F direction toward the image area 3c is slowed by the lens removing unit 11 as compared with the diffusion speed VE0 in the E direction. That is, this diffusion speed V
F1 and the diffusion speed VF0 shown in FIG. 13 have a relationship of VF1 << VF0.

If the microlens 5 immediately before the image area 3c is passed through the lens removing unit 11 at the diffusion speed VF1.
Assuming that the anisotropic conductive paste 4 has reached the group b and has flowed in the directions d and e, respectively, the diffusion amount of the anisotropic conductive paste 4 is further reduced, so that the probability of penetrating the image area 3c and causing an image defect is considerably lowered. At this time, if the diffusion rates in the d and e directions are Vd1 and Ve1, respectively, VD0 >> Vd1 (or VE0
>> Ve1).

In this embodiment, the image area of the anisotropic conductive paste 4 is obtained by simply providing the lens removing portion 11 in which the microlenses 5b are not arranged without changing the manufacturing process or material of the CCD chip 3. It is possible to contribute to the avoidance of the bleeding defect due to the invasion into the 3c, and the manufacturing yield is improved.

Second to fourth aspects of the present invention will be described with reference to FIGS.
An embodiment will be described. 4 to 6 are front views of the main part.

First, FIG. 4 will be described. The shape of the microlens formed outside the image area 3c is the same as that of the image area 3c. However, the gap between the microlenses 5b is changed. That is, the gap Ga between the microlenses 5b in the direction toward the image area 3c.
> Ga <Gb is set as a gap Gb between the microlenses 5b arranged along the periphery of the image area 3c.

In this embodiment, the capillary effect is changed to the vertical direction in which the anisotropic conductive paste 4 penetrates the image area 3c to prevent the anisotropic conductive paste 4 from entering the image area 3c. It is possible to avoid bleeding defects.

Further, in the embodiment shown in FIG. 5, the microlenses 5b are arranged in a staggered manner, unlike the arrangement arranged in the image area 3c. As a result, the image area 3
The microlenses 5b are arranged as a defense wall in the direction in which the anisotropic conductive paste 4 enters c, so that physical intrusion prevention can be performed together.

Further, in the embodiment shown in FIG. 6, the shape of the microlenses 5b is made elliptical, and the longitudinal direction of the adjacent microlenses 5b is arranged so as to easily come into contact with the periphery of the image area 3c. Even with this, the capillary effect has the effect of changing the direction perpendicular to the intrusion of the anisotropic conductive paste into the image area.

There are various conceivable shapes of the microlens 5b other than those described in each of the embodiments shown in FIGS. For example, the microlens 5b may be formed in a complex shape, or a modification in which the microlens 5b is arranged around the bonding pad 3a or the outer shape of the CCD chip 3 is also conceivable.

Further, it is desirable that the outer peripheral portion of the image area 3c has a donut-like all-closed structure, but as shown in the fifth embodiment of the present invention in FIG. 7, it is located outside the image area 3c. The same effect can be obtained by removing a part of the microlens 5b as shown by the broken line.

Further, FIG. 8 shows a sixth embodiment of the present invention. In this embodiment, the filter removing portion 12 not forming the color filter 5a is formed at the same position as the lens removing portion 11 in which the microlens 5b is not formed. In this case, the image removal area 12c is increased by the filter removing section 12 as a result, and the prevention of the anisotropic conductive paste 4 from entering can be improved.

The present invention is not limited to the above-described embodiment, and the connecting member for connecting the CCD chip 3 and the wiring board 1 is not limited to the anisotropic conductive paste 4.
A conductive paste or an adhesive may be used. In addition, the resin sealant for improving the mechanical strength of the package and increasing the sealing property,
It can also be applied to measures to prevent image defects from flowing into the image area.

Further, it is also effective for an ultraviolet erasable memory. It is needless to say that the electric element can be easily applied to other elements requiring a hollow structure, for example, SAW devices which are surface acoustic wave elements, crystal oscillators, and special packages such as LEDs and optical pickups. Yes.

[0040]

As described above, according to the photoelectric conversion device of the present invention, the connection member in the form of paste is formed without penetrating into the image area of the photoelectric conversion element to cause an image defect. be able to.

[Brief description of drawings]

FIG. 1 is an explanatory diagram for explaining a first embodiment of the present invention.

FIG. 2 is a sectional view for enlarging and explaining a main part of the present invention.

FIG. 3 is an explanatory diagram for explaining an operation of the embodiment of FIG.

FIG. 4 is a plan view for explaining the second embodiment of the present invention.

FIG. 5 is a plan view for explaining the third embodiment of the present invention.

FIG. 6 is a plan view for explaining the fourth embodiment of the present invention.

FIG. 7 is a plan view for explaining a fifth embodiment of the present invention.

FIG. 8 is a sectional view for explaining a sixth embodiment of the present invention.

FIG. 9 is an explanatory diagram for explaining mounting of a conventional CCD chip.

10 is a cross-sectional view of the state manufactured in FIG.

11 is an explanatory diagram for explaining a CCD chip used in FIG. 9. FIG.

FIG. 12 is an explanatory diagram for explaining the problem of FIG. 9;

FIG. 13 is an explanatory diagram for explaining the problem phenomenon of FIG. 9;

FIG. 14 is an explanatory diagram for explaining mounting of another conventional CCD chip.

FIG. 15 is an explanatory diagram for explaining mounting of another conventional CCD chip.

[Explanation of symbols]

1 ... Wiring board, 3 ... CCD chip, 3a ... Bonding pad, 3b ... Color filter 5a and microlens 5
Area for forming b, 3c ... Image area, 4 ... Anisotropic conductive paste, 5a ... Color film, 5b ... Microlens, 11 ... Lens removing section, 12 ... Filter removing section.

Claims (7)

[Claims] 1. An image sensor, a bonding pad fixed to a peripheral portion of the image sensor and electrically connected to the image sensor, and formed inside and outside the image area (imaging section) of the image sensor. A photoelectric conversion device comprising: a condensing microlens, wherein at least one of the arrangement and shape of the microlens located outside the image area is changed. 2. The photoelectric conversion device according to claim 1, wherein the microlens formed outside the image area of the image sensor is arranged with a gap from the microlens formed inside the image area. apparatus. 3. The photoelectric conversion device according to claim 2, wherein the microlenses formed outside the image area of the image sensor are annularly arranged along an outer peripheral portion of the image area. 4. The microlenses formed outside the image area of the image sensor are arranged such that the distance between the microlenses adjacent to the center of the image area is wider than that of other portions. The photoelectric conversion device according to claim 1. 5. The photoelectric conversion device according to claim 1, wherein the microlenses formed outside the image area of the image sensor are arranged in a staggered pattern toward the center of the image area. 6. The photoelectric conversion device according to claim 1, wherein a color filter is formed between the microlens and the image sensor. 7. An image sensor, a condensing microlens formed inside and outside the image area (imaging section) of the image sensor, a color filter disposed at least opposite to the inside of the image area, and the microlens. A photoelectric conversion element is configured from a deformable portion obtained by deforming at least one of the arrangement and shape of the lens, and a bonding pad fixed to the peripheral portion of the image sensor and electrically connected to the image sensor, A photoelectric conversion device comprising a conversion element connected face down to a wiring board.