JPH06350066A - Full contact type image sensor and its manufacture - Google Patents

Abstract

PURPOSE:To provide a full contact type image sensor capable of preventing the cross talk of transmitted light and the generation of stray light, and having a higher MTF value and higher resolution. CONSTITUTION:First and second slits 15 and 16 are formed with high precision on the front and rear surfaces of a translucent substrate 1, by forming shading layers 8 and 10 with the same mask along with a circuit conductor layer 2 on the front and rear surfaces of the translucent substrate 1, and a route for light is secured with high precision. Consequently, it becomes possible to obtain high-performance full contact type image sensor unit capable of eliminating the cross talk of light and unnecessary lights (stray light) at the time of reading.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a perfect contact type image sensor that can be used in facsimile machines and the like.

[0002]

2. Description of the Related Art In a conventional perfect contact type image sensor, as shown in FIG. 2, a photocurable transparent insulating resin 25 is provided on the surface of a transparent substrate 21 having a circuit conductor layer 22 formed on the surface thereof. The image sensor chip 23 made of a semiconductor element having the light receiving element array 27 is mounted face down, the extraction electrode 24 formed on the image sensor chip 23 is brought into contact with the circuit conductor layer 22, and the image sensor chip 23 is transparent. A light-shielding layer 28 is provided on the front surface of the transparent substrate 21 so as to cover and protect it with a protective layer 26, and a conductive transparent film 29 is provided on the back surface of the transparent substrate 21 so that the original 30 does not come into direct contact therewith.
It had a structure with. Reference numeral 31 is a light source including an LED array, and 32 is a conveyance roller for the document 30.

[0003]

However, in the above-mentioned structure, the variation in the printing accuracy of the light shielding layer 28 determines the variation in the width of the slit, and as the width of the slit becomes larger, the inside of the transparent substrate 21 becomes larger. There is a problem that crosstalk and stray light are generated, and the MTF value and the resolution are lowered.

In view of the above conventional problems, it is an object of the present invention to provide a perfect contact type image sensor having a high MTF value and a high resolution, which can prevent crosstalk of transmitted light and stray light and a manufacturing method thereof. To do.

[0005]

A perfect contact type image sensor of the present invention is a translucent substrate having a circuit conductor layer formed on the surface thereof, or a circuit conductor layer formed on both front and back surfaces and a through hole formed on both sides thereof. A semiconductor element having a light-transmitting substrate on which a circuit conductor layer of wiring is formed, a light-receiving element array mounted on the surface of the light-transmitting substrate through a light-heat-curing transparent transparent insulating resin, and transparent protection for protecting the semiconductor element. In a perfect contact image sensor including a layer, a conductive light-shielding layer or a circuit conductor except for a portion of the back surface of a light-transmissive substrate that faces the light-receiving element array and a portion that serves as a first slit that transmits light. Form a light-shielding layer consisting of the same layer as the above layer, and form a conductive transparent film over the entire back surface of the light-transmissive substrate, and transmit light to the portion of the light-transmissive substrate surface facing the light-receiving element array. Except for the portion to be the second slit, characterized in that the formation of the light shielding layer made of the circuit conductor layer and the same layer.

Further, the manufacturing method of the perfect contact type image sensor of the present invention, the surface of the translucent substrate, or on both sides,
A metal layer such as gold or copper is formed to a thickness of 2 μm to 35 μm by using a vapor deposition method, a sputtering method or a foil, and then a circuit conductor layer and a light shielding layer are formed by the same process and the same mask by photolithography. Characterize.

[0007]

According to the present invention, since the light shielding layer is formed between the back surface of the transparent substrate and the conductive transparent film and on the surface of the transparent substrate, the first slit and the second slit are provided. It is possible to prevent light crosstalk and stray light, and improve the electrostatic resistance because the light-shielding layer on the back surface of the transparent substrate is made of the same light-shielding layer as the conductive light-shielding layer or the circuit conductor layer. By forming the circuit conductor layer and the light-shielding layer in the same step and in the same mask, the optical path of the light can be accurately ensured, and therefore the sensitivity variation is small, the S / N ratio of image reading, the resolution, and the light transfer. High efficiency,
It is possible to realize a high performance and highly reliable perfect contact type image sensor.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A perfect contact type image sensor according to an embodiment of the present invention will be described below with reference to FIG.

In FIG. 1, reference numeral 1 is a translucent substrate, and 2 is a circuit conductor layer formed on the front and back surfaces of the translucent substrate 1, which constitutes a circuit conductor layer of double-sided wiring through a through hole. ing. Reference numeral 3 denotes an image sensor chip made of a semiconductor element, 4 denotes electrodes provided on the image sensor chip 3, 1
4 is Au provided on the electrode 4 of the image sensor chip 3.
Bumps 5 are photo-thermo-curable transparent insulating resins for mounting the image sensor chip 3 on the transparent substrate 1, 6 is a transparent protective layer for covering and protecting the image sensor chip 3, and 7 is provided on the image sensor chip 3. It is a light receiving element array. Reference numeral 8 denotes a back surface light-shielding layer formed on the back surface of the transparent substrate 1 with a width of 0.05 to 0.5 mm serving as the first slit 15 in the light source arrangement direction from a portion facing the light receiving element array 7, It is formed of the same layer as the circuit conductor layer 2. Reference numeral 9 is a transparent conductive film provided on the entire back surface of the transparent substrate 1 and having a slight conductivity. 10 is a transparent substrate 1
0.1 to 0.7 m that becomes the second slit 16 in the light source arrangement direction from the portion facing the light receiving element array 7 on the surface of
The surface light-shielding layer is formed with a width of m and is formed in the same layer as the circuit conductor layer 2.

Reference numeral 11 is an original to be read, and 12 is an original 11.
Is a light source including an LED array for illuminating the document from above in the document transport direction, and 13 is a conductive transport roller that transports the document to the reading position of the reading unit. Reference numeral 17 denotes an incident angle of the light from the light source 12 in the original conveying direction. Reference numeral 18 denotes a reinforcing plate having a window formed in the image sensor chip mounting portion and the optical path portion on the surface of the transparent substrate 1, and 19 denotes the reinforcing plate 18.
It is an adhesive that adheres integrally to the surface of.

Next, the above complete contact image sensor will be described in more detail.

First, various elements (not shown) and extraction electrodes are formed on a single crystal silicon substrate (wafer) by using a semiconductor process. For each electrode, an Au bump 1 is formed on the surface of the electrode by electroplating or ball bonding.
4 is formed. This wafer is cut by high-precision dicing technology to obtain an image sensor chip 3 composed of semiconductor elements.
make.

Polyethersulfone (PES) and polyetherimide (PE) having a thickness of 10 μm to 200 μm
I), polycarbonate (PC), polyarylate (P
A), polyetheretherketone (PEEK), polyethylene terephthalate (PET), or other transparent substrate 1 on both front and back surfaces of a metal such as gold or copper by vapor deposition, sputtering, or foil. 2 μm
Then, the circuit conductor layers 2 on both the front and back surfaces, and the back light-shielding layer 8 and the front light-shielding layer 10 which are the same layer as the circuit conductor layers 2 are formed by photolithography. At that time, the second slit 16 of 0.1 to 0.7 mm is formed on the front surface side of the translucent substrate 1, and the first slit 15 of 0.05 to 0.5 mm is formed on the back surface side. Then, the surfaces of the circuit conductor layer 2, the back surface light-shielding layer 8 and the front surface light-shielding layer 10 are solder-plated.

Further, palladium, indium oxide, tin oxide or the like is formed on the entire rear surface (original contact surface) of the transparent substrate 1 so as to have static resistance and abrasion resistance of 10 ⁹ Ω / □ or less. Pencil hardness of 3H to 8H such as urethane acrylate containing conductive particles, thickness of 10 μm
A transparent conductive film 9 having a thickness of about 30 μm is provided. By providing the back surface light-shielding layer 8 in this manner, unnecessary light (stray light) due to reflection of light from the light source 12 on the back surface (original contact surface) of the transparent conductive film 9 can be erased, and the light transmitting property can be eliminated. By making the substrate 1 thin and providing the first slit 15, crosstalk of light can be prevented.

At a predetermined position on the surface of the light-transmissive substrate 1, a predetermined amount of an acrylate-based light-heat-curable transparent insulating resin 5 is applied by a stamping method or a screen printing method, and the image sensor chip 3 is applied thereon. Is placed face down so that the Au bumps 14 come into contact with the solder plating provided on the predetermined circuit conductor layer 2. Thereafter, while applying pressure from above the image sensor chip 3, ultraviolet rays are irradiated through the light-transmissive substrate 1 to the light-heat combined curing type transparent insulating resin 5 to be cured. Further, this is put in an electric furnace and placed in a furnace having a melting point of solder plating (170 to 190 ° C.) or a temperature higher than the curing temperature of the light-heat-curable transparent insulating resin 5 (100 ° C. or higher) for a certain time (5 minutes to 20 minutes) Minutes)
The heat treatment is performed to melt the solder plating 3, and the photothermal combined curing type transparent insulating resin 5 which is shaded by the circuit conductor layer 2 and which is not completely cured is completely cured to complete the mounting. As the photothermal combined curable transparent insulating resin 5 for mounting the image sensor chip 3 on the translucent substrate 1, an acrylate-based, urethane acrylate-based or epoxy acrylate-based photothermal combined curable transparent insulating resin is used for adhesion and light It is preferable in terms of sensitivity.

After that, the adhesive 19 is applied to the surface of the translucent substrate 1 (semiconductor element mounting surface) other than the mounting portion of the image sensor chip 3, the optical path portion and the solder joint portion, and pressure is applied. The surface of the translucent substrate 1 (semiconductor element mounting surface) and the reinforcing plate 18 are adhered to each other with good planarity, and in order to protect the image sensor chip 3, a transparent silicone or a transparent material is placed in the window of the reinforcing plate 18 from above. A transparent resin such as acrylate is evenly applied with a dispenser and the height after curing is 2
mm or less, refractive index 1.6 or less, pencil hardness after curing 2H to 8
A transparent protective layer 6 of H is formed. At this time, the transparent resin (transparent protective layer 6) is prevented from squeezing out by sufficiently adhering the reinforcing plate 18 and the translucent substrate 1 with the adhesive 19. In the perfect contact type image sensor thus created, the image sensor chip 3 is fixed with resin, and at the same time, the electrode 4 can be electrically and reliably connected to the conductor circuit layer 2 by soldering, which is highly reliable and easy. , Short time,
It can be manufactured at low cost.

The conductive transport roller 12 has a sheet resistance of 10.
^Using conductive rubber in which an electrically conductive additive such as carbon black or acetylene black of ⁵ Ω / □ or less, zinc oxide or tin oxide is mixed with an elastomer base material such as polyurethane or silicone rubber By connecting the to the ground, the static electricity generated by rubbing the document is eliminated and noise is reduced.

In the above complete contact type image sensor, the conductive transparent film 9 on the back surface of the translucent substrate 1 is used as the original contact surface, and the transparent protective layer 6 and the light / heat combined curing type transparent insulating resin are applied from above by the light source 12. 5, by irradiating the original 11 with light through the transparent substrate 1 and the conductive transparent film 9, the optical information from the original 11 is received through the conductive transparent film 9, the transparent substrate 1, and the photothermal combined curing type transparent insulating resin 5. Element array 7
You can read the information on the original directly.

Further, the incident angle 17 of the light from the light source 12 from the document conveying direction is set to 30 degrees from directly above the image sensor chip 3 (incident angle 0 degree), and the reflected light from the illuminated original 11 is transmitted. By guiding the light to the image sensor chip 3 provided on the surface of the optical substrate 1, the optical information from the original 11 can be read at a high resolution without a lens system and with no crosstalk of light (MTF value 50% ( 4 lp / m
m)) At the same time, the size of the perfect contact image sensor itself can be dramatically reduced. Further, by bringing the conductive transparent film 9 into contact with the back surface of the transparent substrate 1 and grounding the conductive transparent film 9, it is possible to improve the electrostatic resistance and abrasion resistance.

With the above configuration, the S for image reading is read.
The / N ratio, resolution, and light transfer efficiency can be maintained at a high level, noise can be reduced, and light information from a document can be read at high resolution without crosstalk of light without a lens system.
In addition, the light transfer efficiency is 4 to 4 compared with the conventional lens system.
It is about 5 times, which can contribute to the cost reduction of the light source (LED array).

In the above embodiment, the circuit conductor layers 2 are formed on both front and back surfaces of the translucent substrate 1, double-sided circuit conductor layers are provided through the through holes, and the back surface light-shielding layer 8 also serves as the circuit conductor layer 2. Although the example in which the circuit conductor layer 2 is formed of the same layer is shown, the circuit conductor layer 2 is formed only on the front surface of the transparent substrate 1, and the back surface light shielding layer 8 on the back surface of the transparent substrate 1 is formed of a conductive light shielding layer. You may.

[0022]

As described above, according to the present invention, the light-shielding layer is formed between the back surface of the transparent substrate and the transparent conductive film and on the surface of the transparent substrate as described above, and the first slit and the second slit are formed. Since it is provided, it is possible to prevent the occurrence of light crosstalk and stray light, and improve the electrostatic resistance because the light-shielding layer on the back surface of the transparent substrate is made of the same layer as the conductive light-shielding layer or the circuit conductor layer. be able to. Further, by forming the circuit conductor layer and the light-shielding layer in the same step and in the same mask, the optical path of the light can be secured with high accuracy, and the crosstalk and stray light of the light at the time of reading can be further eliminated. Therefore, according to the present invention, the sensitivity variation is small, the S / N ratio of image reading,
It is possible to realize a high performance and highly reliable perfect contact image sensor having high resolution and high light transfer efficiency.

[Brief description of drawings]

FIG. 1 is a sectional view of a perfect contact type image sensor according to an embodiment of the present invention.

FIG. 2 is a sectional view of a conventional full-contact image sensor.

[Explanation of symbols]

 1 Translucent Substrate 2 Circuit Conductor Layer 3 Image Sensor Chip (Semiconductor Element) 4 Electrode 5 Photothermal Combined Curing Transparent Insulating Resin 6 Transparent Protective Layer 7 Photoreceptor Array 8 Backside Light-shielding Layer 9 Transparent Conductive Film 10 Surface Light-shielding Layer 15 1st Slit 16 Second slit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shinji Fujiwara 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (6)

[Claims] 1. A semiconductor element having a light-transmissive substrate having a circuit conductor layer formed on the surface thereof, and a light-receiving element array mounted on the surface of the light-transmissive substrate via a photo-thermosetting curable transparent insulating resin, and a semiconductor. In a perfect contact image sensor having a transparent protective layer for protecting elements, a conductive substrate is provided except for a portion of the back surface of the transparent substrate facing the light receiving element array and a portion serving as a first slit for transmitting light. Forming a light shielding layer,
A conductive transparent film is formed on the entire back surface of the transparent substrate, and a circuit conductor layer is formed on the surface of the transparent substrate except a portion facing the light receiving element array and a portion serving as a second slit that transmits light. A complete contact type image sensor having a light-shielding layer formed of the same layer. 2. A circuit conductor layer for double-sided wiring is provided by forming circuit conductor layers on both front and back surfaces of a transparent substrate, and a circuit conductor layer for double-sided wiring is provided, and a light-heat-curable transparent insulating resin is provided on the surface of the transparent substrate. A semiconductor element having a light-receiving element array is mounted therethrough, the semiconductor element is covered with a transparent protective layer, and a portion of the back surface of the transparent substrate facing the light-receiving element array and a portion serving as a first slit for transmitting light are formed. Except for forming a light-shielding layer consisting of the same layer as the circuit conductor layer, a conductive transparent film is formed over the entire back surface of the light-transmissive substrate, and a portion facing the light-receiving element array is formed on the front surface of the light-transmissive substrate. A perfect contact type image sensor, characterized in that a light shielding layer made of the same layer as the circuit conductor layer is formed except for a portion which becomes a second slit which transmits light. 3. The width of the first slit is 0.05 to 0.5 m.
The perfect contact type image sensor according to claim 1 or 2, wherein m is m. 4. The width of the second slit is 0.1 to 0.7 mm.
The perfect contact type image sensor according to claim 1 or 2, characterized in that. 5. The process of manufacturing the perfect contact image sensor according to claim 1, wherein a metal layer such as gold or copper is formed on the surface of the translucent substrate to a thickness of 2 μm by vapor deposition, sputtering or foil. To 35 μm, and thereafter, the circuit conductor layer and the light shielding layer are formed by the same process and the same mask by the photolithography method. 6. The process of manufacturing the perfect contact type image sensor according to claim 2, wherein a metal layer such as gold or copper is formed on both the front and back surfaces of the translucent substrate by vapor deposition, sputtering or foil. A method for manufacturing a perfect contact type image sensor, which comprises forming the film to have a thickness of 2 μm to 35 μm, and then forming the circuit conductor layers and the light shielding layers on both surfaces by the same process and the same mask by a photolithography method.