JPH0777411B2 - Solid-state imaging device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Field of Industrial Application) The present invention relates to a solid-state imaging device, and in particular, to an insulating substrate (that is, a driving circuit in which a circuit formed on the surface is only a wiring pattern and input / output terminals). The present invention relates to a solid-state image pickup device in which a solid-state image pickup element is provided on an insulating substrate on which circuits and the like are not integrally formed.

(Prior Art) Conventionally, as a solid-state image pickup device, an insulating substrate on which a driving circuit and the like are not integrally formed is used, that is, a circuit formed on the surface of a transparent insulating substrate has only a wiring pattern and input / output terminals. Some are known.

Such a solid-state image pickup device is generally manufactured by first forming a plurality of photoelectric conversion elements on a semiconductor substrate by a photolithography process to fabricate the solid-state image pickup element, and then mounting the solid-state image pickup element on a substrate such as a ceramic substrate. It is obtained by applying a predetermined wiring with.

FIG. 4 is a diagram showing a conventional example of a sectional structure of a solid-state imaging device 10 of this type, showing a case of a one-dimensional contact type device.

In the figure, the mount agent is placed on the ceramic substrate 11.
A solid-state image sensor 13 is fixed via 12 The solid-state image pickup device 13 has a plurality of light conversion elements arranged one-dimensionally (a direction perpendicular to the paper surface).

A predetermined wiring pattern made of a conductor film is printed on the upper surface of the ceramic substrate 11. Then, a predetermined portion of this print pattern and the external wiring terminal of the solid-state imaging device 13 are bonding wires made of gold or aluminum thin wires.
Connected by 14. Input / output connector pins 15 are connected on the wiring pattern at the end of the ceramic substrate 11. As a result, the semiconductor integrated circuit (photoelectric conversion element) in the solid-state image pickup device 13 is bonded to the bonding wire 14,
It is electrically connected to an external drive circuit through the wiring pattern on the ceramic substrate 11 and the input / output connector pin 15.

Further, in order to protect the solid-state image pickup device 13, a glass cover 17 is fixed on the ceramic substrate 11 with an organic sealant 16.

In order to read the writing pattern on the original 1 by the solid-state imaging device 10, the original 1 is illuminated by the light source 2, and the reflected light is passed through the SELFOC lens array 3 to the photoelectric conversion unit 13a on the solid-state imaging device 13. Make them image. In the figure, this optical path is indicated by a chain line. Note that in order to obtain a color image, a filter corresponding to the hue is provided on the photoelectric conversion unit 13a. In this way, the amount of light according to the shade of the image-formed writing pattern is converted into an electric signal.

As described above, when the drive circuit is not integrally formed as the insulating substrate (ceramic substrate 11 in FIG. 4) of the solid-state imaging device, the insulating substrate having a small area is used. be able to. Therefore, as compared with the case where the insulating substrate integrally formed with the drive circuit is used, there is an advantage that an insulating substrate having good surface flatness and smoothness can be used.

That is, when the insulating substrate integrally formed with the drive circuit is used, the area of this insulating substrate must be increased. Here, in the case of manufacturing an insulating substrate having a certain level of flatness and smoothness, the larger the area, the lower the yield, and the higher the cost. Therefore, when using an insulating substrate with a large area,
The flatness and smoothness of the surface cannot be made too high.

On the other hand, when the drive circuit is not formed on the insulating substrate, the area of the insulating substrate can be reduced, so that the one having good surface flatness and smoothness can be used.
Therefore, as compared with the case where the insulating substrate integrally formed with the drive circuit is used, the positioning is easier and the mount position accuracy can be improved.

(Problems to be Solved by the Invention) However, such a solid-state imaging device has the following problems.

(1) When fixing the solid-state image sensor to the insulating substrate, an optical pattern recognition device having a deep depth of field must be used.

The above-mentioned solid-state imaging device 13 is usually manufactured using a large wafer having a diameter of 4 to 5 inches in order to reduce costs.
Here, such a large-sized wafer requires a thickness of 0.6 mm or more in order to secure mechanical strength. Therefore, the thickness of each solid-state imaging device 13 is also 0.6 mm or more.

Here, when the solid-state imaging device 13 is fixed on the ceramic substrate, an optical pattern recognition device is used to align the solid-state imaging device 13 with the wiring pattern. At this time, it is necessary to simultaneously recognize the position of the solid-state image sensor 13 and the position of the wiring pattern by using this optical pattern recognition device.

However, since the solid-state image sensor 13 is thick as described above, if the optical pattern recognition device has a shallow depth of field, it is not possible to focus on the surface of the wiring pattern and the upper surface of the solid-state image sensor at the same time. For this reason, conventionally, it is not possible to perform highly accurate alignment, and as a result, as described above, it is possible to use a sufficient mount position accuracy despite the use of an insulating substrate having a good surface flatness and smoothness. Couldn't get In other words, although the conventional device is superior to the device in which the drive circuit is formed on the insulating substrate, "the mounting position accuracy is good because the insulating substrate with good surface flatness and smoothness can be used. However, the advantage of this type of solid-state imaging device cannot be fully utilized.

In particular, in a two-dimensional type device (not shown), that is, in a device in which a photoelectric conversion element is two-dimensionally arranged, a ceramic package is used instead of the glass cover, so there is a shrinkage phenomenon that occurs when the ceramics are laminated and sintered, The accuracy of the wiring pattern on the ceramic substrate also deteriorates, and the mounting position accuracy further deteriorates.

(2) The device cannot be downsized.

As shown in FIG. 4, the solid-state image sensor 13 and the wiring pattern are connected by the bonding wires 14, so that the glass cover 17 should not touch the bonding wires 14.
Requires a sufficient internal volume. Further, since it is necessary to consider the escape portion of the jig during wire bonding, a larger internal volume of the glass cover 17 is required. Similarly, in a two-dimensional device (not shown), a large volume of the ceramic package is required. Therefore, the conventional device has a problem that it cannot be downsized.

(3) Airtightness is poor.

As described above, in the conventional solid-state imaging device, the glass cover
This glass cover because 17 requires a large internal volume
In the step of sealing 17 with the sealant 16, the air inside the glass cover 17 expands, and an airway is generated in the sealant 16. Therefore, there is a problem that the airtightness of the device is deteriorated.

Therefore, the present invention has good mounting accuracy of the solid-state imaging device,
Moreover, it is an object of the present invention to provide a small-sized solid-state imaging device having excellent airtightness.

[Structure of Invention]

(Means for Solving the Problems) In the solid-state imaging device according to the present invention, the circuit formed on the surface is the same as the transparent insulating substrate having only the wiring pattern and the input / output terminal, and the external wiring terminal and the photoelectric conversion unit. A solid-state imaging device provided on a surface, aligned with an optical pattern recognition device from the back side of the transparent insulating substrate, and the external wiring terminals being bump-connected to the wiring pattern of the transparent insulating substrate; And a protection means for covering the element.

(Operation) In the present invention, a transparent insulating substrate is used, and further, when the solid-state image sensor is fixed on the transparent insulating substrate, the position of the solid-state image sensor and the position of the wiring pattern by the optical pattern recognition device are used. It is decided that the recognition is performed through the transparent insulating substrate. Accordingly, in the present invention, the alignment is performed by focusing the surface of the wiring pattern and the lower surface of the solid-state image sensor at the same time, instead of simultaneously focusing on the surface of the wiring pattern and the upper surface of the solid-state image sensor. be able to. For this reason, the depth of field corresponding to the thickness of the solid-state image sensor is not required, and therefore, excellent mounting accuracy can be obtained even if the depth of field of the optical pattern recognition device is shallow.

Further, in the present invention, since the wiring pattern of the transparent insulating substrate and the external wiring terminal of the solid-state imaging device are directly bump-connected, the space occupied by the bonding wire is larger than that in the conventional device connected by the bonding wire. No need to secure. Therefore, the size of the device can be reduced, and the device can be made airtight.

(Example) Hereinafter, the present invention will be described based on an illustrated example.
FIG. 1 is a diagram showing a sectional structure and a reading mechanism of a solid-state imaging device according to an embodiment of the present invention.

In this embodiment, a low alkaline glass (# 7059) manufactured by Corning Incorporated is used as the transparent insulating substrate 21, and a wiring pattern made of a conductive film is formed on the surface (lower surface in FIG. 1) of the transparent insulating substrate 21. Formed. As this wiring pattern,
From the transparent insulating substrate 21 side, a thin film composed of three layers, in which a chromium film, a palladium film, and a gold film were deposited in this order, was used.

The solid-state imaging device 23 is directly bump-bonded to the transparent insulating substrate 21. That is, the external wiring terminals of the solid-state imaging device 23 and the wiring pattern on the transparent insulating substrate 21 are directly connected by the bump electrode portions 24. In this embodiment, gold or an alloy of gold and tin is used for the bump electrode portion 24. This bump bonding may be performed by forming bumps on the transparent insulating substrate 21 side, the solid-state image pickup device 23 side, or both sides, and bonding them by thermocompression bonding or the like.

In the alignment at this time, first, the solid-state imaging device 23 is mechanically brought close to a predetermined position on the transparent insulating substrate 21, and the bump pattern is formed with a microscope or an ITV camera from above in FIG. 1 through the transparent insulating substrate 21. Recognize the wiring pattern,
You only need to match both. At this time, instead of the actual bump pattern, a pseudo pattern provided at a position relative to the bump position may be used.

As described above, since the alignment can be performed through the transparent insulating substrate 21 and the distance between the bump pattern and the wiring pattern in the depth direction (vertical direction in the figure) is small, even if the depth of field of the microscope or the ITV camera is shallow. The connection can be made more accurately than the conventional connection using the bonding wire.

In the device according to the present invention, since the solid-state imaging device 23 is directly connected to the transparent insulating substrate 21 via the bump electrode portion 24 as described above, the transparent insulating substrate 21 and the solid-state imaging device 23 have a coefficient of thermal expansion. It is preferable to use a material having approximately the same. This is because when the coefficient of thermal expansion is different, the problem that cracks occur due to thermal stress occurs. The low-alkali glass used in this example is one of the preferable materials having a thermal expansion coefficient substantially equal to that of silicon which constitutes the solid-state image pickup device 23.

After this, a transparent insulating cover is applied with the organic sealant 26.
27 is adhered to the transparent insulating substrate 21. This adhesion can be performed by applying the sealant 26 to the transparent insulating cover 27 and thermosetting the transparent insulating substrate 21 while applying pressure.

In this embodiment, since the external connection terminals of the solid-state image pickup device 23 and the wiring pattern are directly bump-connected, the internal volume of the transparent insulating cover 27 can be made smaller than in the case where the conventional bonding wire is used for the connection. it can. Further, since the internal volume can be reduced in this way, the expansion amount of air in the step of sealing using the sealant 26 is small, and the airway is unlikely to occur in the sealant 26, so that the airtightness is improved. You can also let it.

The transparent insulating cover 27 is preferably made of the same material as the transparent insulating substrate 21. This is because the stress strain after sealing is reduced and the airtightness is further improved.

Then, the input / output connector pin 25 is connected to the end of the wiring pattern of the transparent insulating substrate 21 to electrically connect to an external drive circuit. Here, in order to secure the mechanical strength, the input / output connector pin 25 may be soldered to the wiring pattern of the transparent insulating substrate 21 and sealed with the mold resin.

The pattern reading by the solid-state imaging device having such a structure is performed as follows. The original 1 is irradiated with light from the light source 2, and the reflected light is guided to the photoelectric conversion unit 23a of the solid-state image sensor 23 through the SELFOC lens array 3. Since the transparent insulating substrate 21 is made of a transparent material,
An image of the writing pattern on the original 1 is formed on the photoelectric conversion unit 23a. An image signal is formed by electric charges generated according to the brightness of this image, and this signal is transmitted from the solid-state imaging device 23 through the bump electrode portion 24, the wiring pattern on the transparent insulating substrate 21, and through the input / output connector pin 25. Led to an external circuit.

FIG. 2 shows a solid-state image pickup device 20 according to another embodiment of the present invention.
FIG. 6 is a diagram showing a state in which the document is closely attached to the original 1 and reading is performed. The original 1 is brought into close contact with the surface of the transparent insulating substrate 21 of the solid-state imaging device 20 by the platen roller 4. An image formed by the transmitted light of the document 1 is formed on the photoelectric conversion unit 23a.

This embodiment is particularly suitable for reading a writing pattern written on a transparent film or the like. However, since image formation is performed without using a lens system, there is a problem that when light other than the pattern to be read enters the photoelectric conversion unit 23a, it appears as a noise component. Therefore, the device shown in FIG. 2 is provided with a light shielding film 28 for shielding the incident light other than the photoelectric conversion portion 23a. In addition, this light-shielding film 28
Can be formed simultaneously with the step of forming a wiring pattern on the transparent insulating substrate 21.

FIG. 3 is a sectional structural view of a solid-state imaging device according to still another embodiment of the present invention. This device has a transparent insulation cover
A resin is used instead of 27 to protect the solid-state imaging device 23. That is, the transparent resin body 29 is filled around the solid-state imaging device 23, and the opaque resin body 30 is formed as the exterior thereof. By filling the inside with the transparent resin body 29, the light that has passed through the transparent insulating substrate 21 is converted into a photoelectric conversion portion 23a.
Can be easily guided to the outside and an opaque resin body on the outside
By forming 30, it is possible to block unnecessary external light.

In addition, in the above-described embodiment, the solid-state imaging device has been described with respect to the one-dimensional line sensor having a plurality of one-dimensionally arranged light conversion elements. The same can be applied to an originally arranged line sensor and an area sensor using a solid-state image sensor having a plurality of two-dimensionally arranged light conversion elements.

〔The invention's effect〕

As described above, according to the present invention, a transparent insulating substrate is used, and the position of the solid-state image sensor and the position of the wiring pattern by the optical pattern recognition device when the solid-state image sensor is fixed on the transparent insulating substrate. Since the recognition is performed through the transparent insulating substrate, excellent mounting accuracy can be obtained even if the depth of field of the optical pattern recognition device is shallow.

Further, according to the present invention, since the wiring pattern of the transparent insulating substrate and the external wiring terminal of the solid-state image sensor are directly bump-connected, the internal volume of the protection means can be reduced, and therefore the device can be made compact. And airtightness can be achieved.

[Brief description of drawings]

FIG. 1 is a diagram showing a sectional structure and a reading mechanism of a solid-state imaging device according to an embodiment of the present invention, and FIG. 2 is a sectional structure and a reading mechanism of a solid-state imaging device according to another embodiment of the present invention. FIG. 3 is a cross-sectional view of a solid-state imaging device according to yet another embodiment of the present invention, and FIG. 4 is a cross-sectional view of a conventional solid-state imaging device and a reading mechanism. 1 ... Original, 2 ... Light source, 3 ... SELFOC lens array, 4 ... Platen roller, 10 ... Solid-state imaging device, 11
...... Ceramic substrate, 12 ...... Mounting agent, 13 ...... Solid-state image sensor, 13a ...... Photoelectric conversion part, 14 ...... Bonding wire, 15 ...... Input / output connector pin, 16 ...... Sealant, 17 ...
… Glass cover, 20 …… Solid-state imaging device, 21 …… Transparent insulating substrate, 23 …… Solid-state imaging device, 23a …… Photoelectric conversion part, 24…
… Bump electrode part, 25 …… input / output connector pin, 26 …… sealant, 27 …… transparent insulating cover, 28 …… shading film, 29 ……
Transparent resin body, 30 ... Opaque resin body.

Claims (7)

[Claims] 1. A transparent insulating substrate on one surface of which a circuit consisting only of a wiring pattern and input / output terminals is formed, a photoelectric conversion unit which receives incident light from the other surface side of the transparent insulating substrate, and an optical pattern recognition device. A solid-state image pickup device comprising: a solid-state image pickup device provided on the same surface with an external connection terminal that is aligned and bump-connected to the wiring pattern; and a protection unit that covers the solid-state image pickup device. 2. The solid-state image pickup device according to claim 1, further comprising a shielding film formed on the transparent insulating substrate for shielding light incident on portions other than the photoelectric conversion portion. 3. The solid-state imaging device according to claim 1, wherein the protection means is made of resin. 4. The solid-state image pickup device according to claim 3, wherein said protection means has a transparent resin body and an opaque resin body formed as an exterior thereof. 5. The solid-state imaging device according to any one of claims 1 to 4, wherein the solid-state imaging device has a plurality of one-dimensionally arranged light conversion elements. apparatus. 6. A solid-state image pickup device according to claim 1, wherein the plurality of solid-state image pickup devices are arranged in a one-dimensional manner and bump-connected to the wiring pattern. The solid-state imaging device according to claim 1. 7. The solid-state imaging device according to claim 1, wherein the solid-state imaging device has a plurality of two-dimensionally arranged light conversion elements. .