JPH03150872A - Complete contact type image sensor - Google Patents

Abstract

PURPOSE:To obtain a complete contact type image sensor having a high long term reliability by a method wherein a thin glass plate is provided above a photoelectric converting film with an adhesive layer there-between and a silicon film containing nitrogen atoms is provided on the thin glass plate surface which is brought into contact with the adhesive layer. CONSTITUTION:A light shielding layer 102 having a lighting window 110 is provided on a transparent substrate 101 and covered with a transparent insulating layer 103. A photoelectric transducer composed of a lower metal electrode 104, an upper metal electrode 106 and a photoelectric converting film 105 held between the electrodes 104 and 106 is formed on the transparent insulating layer 103. A thin glass plate 109 is bonded onto the photoelectric transducer with an adhesive layer 107 therebetween. A silicon film 108 containing nitrogen atoms is formed on the thin glass plate 109 surface which is brought into contact with the adhesive layer 107. Therefore, impurity ions such as Na<+>, K<+> and Cl<-> which are diffused from the thin glass plate 109 during a long term usage are captured by the silicon film 108 containing nitrogen atoms and the corrosion of the photoelectric transducer and wirings can be suppressed. With this constitution, the long term reliability can be improved.

Description

[Detailed description of the invention] 〔Technical field〕 The present invention relates to a complete contact type image sensor.

[Prior art]

In a fully contact image sensor that illuminates the original through a transparent substrate and takes the reflected light directly into the photoelectric conversion element, keeping the gap between the original and the photoelectric conversion element constant increases the S/N ratio of 1 in total. is important above.

Therefore, a technique has been proposed in which the gap between the 1M frame and the photoelectric conversion element is kept constant using a protective layer. Examples include (a) Japanese Patent Publication No. 58-46186, (b
) JP-A-61-101164.

In (a), a thin glass plate with a thickness of about 50 to 100 μm is pasted on the photoelectric conversion element with a transparent adhesive, and in (b), a protective layer is made of acrylic resin.

It is composed of an organic material whose main component is melanin resin, styrene resin, polyester resin, or silicone resin.

In (a), since the protective layer is made of thin glass, it has the advantage of having sufficient abrasion resistance against the passage of the original (
As a result of the experiment, there was no problem with the output image before and after passing 10,000 sheets.)

However, thin glass is usually soda glass or pyrex glass.

For long-term use, Na, K'' ions and C
There is a problem that f1- ions and the like diffuse from the thin glass.

This is especially noticeable in environments with high temperature and high humidity.

Naturally, Na is also removed from the transparent substrate and adhesive.
There is a concern about the diffusion of ions such as , K'', CQ-, etc., but for the transparent substrate, it is recommended to use quartz glass or to form a thin film with a strong gettering effect such as silicon nitride or BPSG on the transparent substrate. This can prevent ion diffusion.

For adhesives, it is possible to prevent ion contamination by changing the raw materials and synthesis process. For example, in the case of epoxy resins, such as bisphenol A type resins used at the bottom of the process, it is necessary to increase the efficiency of the dehydrochloric acid reaction and thoroughly wash away residual alkali, and cycloaliphatic epoxy resins that do not use alkali during synthesis. By switching to resin, high purity can be achieved.

Ions such as Na, K", CQ-, etc. that diffuse through the thin glass accelerate corrosion of photoelectric conversion elements or wiring, which poses a problem in long-term reliability.

On the other hand, regarding (b), since the protective layer is made of an organic material, it is relatively easy to prevent ions and impurities such as Na, K", CQ-, etc. from being mixed in the raw material. Therefore, long-term reliability is expensive.

However, since it is an organic material, its hardness is low and its abrasion resistance during document feeding is insufficient. As a result, image output gradually deteriorates.

〔the purpose〕

An object of the present invention is to overcome the above-mentioned drawbacks and provide a fully contact type image sensor that has high reliability (corrosion and deterioration of single image output) over a long period of time.

〔composition〕

The present invention has a lighting window and a photoelectric conversion film on a transparent substrate,
A fully contact image sensor comprising a thin glass plate further provided above with an adhesive layer interposed therebetween, characterized in that a silicon film containing nitrogen atoms is provided on the surface of the thin glass plate that is in contact with the adhesive layer. do.

Preferably, the silicon film further contains oxygen atoms.

The silicon film containing nitrogen is formed by plasma CVD using 5in4 gas and NH2 gas or N2 gas, sputtering using Si, N, and targets, or reactive sputtering using a Si target and introducing N2 and NH3 gases. Ru.

The thickness should be 5 to satisfy the function of capturing impurities.
000 to about 3 μm is sufficient.

Using the above method, a silicon film containing nitrogen atoms is
It is amorphous. The proportion of nitrogen atoms is 30-65 II
loQ% is desirable. According to plasma CVD method 1 reactive sputtering, hydrogen atoms are often included.

Note that the internal stress of a silicon film containing nitrogen can be controlled by the film formation conditions, so the internal stress can be reduced by appropriately selecting the film formation conditions. As a result, even after forming a silicon film containing nitrogen atoms, the thin glass does not undergo deformation such as warping or twisting. Therefore.

The process of pasting becomes easier and an improvement in yield can be expected.

Further, in addition to nitrogen atoms, oxygen atoms may be included to improve adhesion to the adhesive. In that case.

The proportion of nitrogen atoms is preferably 10 to 60n+o12%.

FIG. 1 shows an example of a complete contact type image sensor of the present invention.

A light shielding layer 102 having a lighting window 110 on a transparent substrate 101
is provided and covered with a transparent insulating layer 103. A photoelectric conversion element consisting of a photoelectric conversion film 105 sandwiched between a lower metal electrode 104 and an upper transparent electrode 106 is formed thereon. The photoelectric conversion element is coated with a passivation film (not shown) if necessary.

A thin glass plate 109 is attached onto the photoelectric conversion element with an adhesive layer 107 interposed therebetween. The thin glass 109 has a silicon film 10 containing nitrogen atoms on the surface in contact with the adhesive layer 107.
8 is formed.

Therefore, impurities such as Na, K'', and cn-, etc., diffuse from the thin glass 109 during long-term use.

Since the nitrogen atoms are captured by the silicon film 108 containing nitrogen atoms, corrosion of photoelectric conversion elements and wiring can be significantly suppressed.

Furthermore, since the surface in contact with the original is made of thin glass 109, it has sufficient abrasion resistance, and there is no deterioration in image output even after long-term use, ensuring a stable S/N ratio and resolution.

Although FIG. 1 describes a sandwich type photoelectric conversion element, the present invention also applies to a coplanar type photoelectric conversion element.
Can be used similarly.

Next, each layer will be explained.

The transparent substrate 101 is made of Pyrex, quartz glass, or a polymer resin such as polyethylene, polypropylene, or polyacrylic resin. Note that in order to prevent diffusion of impurities such as Na, K", Cf1-, etc., it may be covered with a silicon nitride film, BPSG, or the like.

C, r, Mo, Ti, and Ni on the transparent substrate 101.

Light shielding N1 made of metals such as W and Ta, alloys, and silicides
02 is provided, and a lighting window 110 is formed by photolithography. SiO□, Si on top.

N4. It is covered with a transparent insulating layer 103 such as A Qz Oz.

A photoelectric conversion element is formed thereon. Lower metal electrode 10
4 is made of metal, alloy, or silicide such as CrlMo, Ti, Ni, W, and Ta. The upper transparent electrode 106 is
O1In20. , Sn○2, etc. Photoelectric conversion film 10
6 mainly consists of a hydrogenated amorphous silicon film, and P
It has an IN junction, a PI junction, a Schottky junction, or a beta junction to which oxygen, carbon, or nitrogen atoms are added, and achieves a high S/N ratio.

Thereafter, if necessary, it is coated with Si, N, 5in2 or a transparent polymer resin such as polyimide resin, epoxy resin, polyester resin, polyacrylic resin, etc. to form a passivation film.

The adhesive layer 107 is made of epoxy resin, polyester resin, polyacrylic resin, and polyurethane resin, and has a thickness of 1
It is usually 10 μm or less.

The thin glass 109 is made of soda glass or pyrex glass, and the thickness is determined by the pixel density, but is 8 dots/
In the case of ya-16 dots/mm, it is about 30 to 70 μI.

A silicon film 108 containing nitrogen atoms is formed on one surface of the thin glass 109 . The silicon film 109 containing nitrogen is S
Plasma CVD using iH, gas and NH3 gas or N2 gas, sputtering using Si, N4 target, or N2, NH,
The film is formed by reactive sputtering that introduces a gas.

The thickness is set to 5 to satisfy the function of capturing impurities.
000 to about 3 μm is sufficient.

When the above method is used, the silicon film containing nitrogen atoms is amorphous. The proportion of nitrogen atoms is 30-65 oQ
% is desirable.

FIG. 2 shows another example of this case.

The lower metal electrode 302 also serves as a light shielding layer and the lighting window 31
It has 0. The other configurations are the same as in FIG. 1.

〔Example〕

Example 1 1500 Cr films were formed on a 240×30×1.6a+mt quartz glass by vacuum evaporation, and a lower metal electrode (common electrode) having a light window of 8 dots/mm and 1728 dots was formed by photolithography.

A three-layer hydrogenated amorphous silicon film is formed thereon by plasma CVD, and an optical path is secured by photolithography to form a photoelectric conversion film.

The hydrogenated amorphous silicon layer has the following structure.

pa-5i:O:H Film thickness 500 people Gas Co2/Sx)! , == 1 (molar ratio) B, H
JSiH4= 5 X 10” SiH, /H, = 0.2 a-5i:H Film thickness 7500 people gas SiH, /H, = 0.2 na-3i:H Film thickness 350 people gas P)la/5iH4= 1 x 10-'5in
4/) l, =0.2 Then, by DC magnetron sputtering using a target of I n,03+S n O□5wt%.

750 ITO films were formed, and an upper transparent electrode (fli separate electrode) was formed by photolithography.

Then, by sputtering using SiO as a target, a film of SiO is formed to a thickness of 1.5 μm to form a passivation layer, thereby forming a photoelectric conversion element.

A silicon film containing nitrogen atoms is formed to a thickness of 2 μm on one surface of a 240×8×0, 05 ma+t thin plate glass by plasma CVD. The film forming conditions are as follows.

Gas N, / S i H, = 15NH3/S i
H4=5 After that, the surface on which the silicon film containing nitrogen atoms is attached is pasted onto the photoelectric conversion element using an epoxy resin (photocurable liquid type, 100 cp). Adhesive layer thickness is 5-10μ
■It is.

Connect the IC to the individual electrodes with wire bonding 2.5
Drive at a speed of ms/1ine.

As a result of passing 135,000 sheets of A4 size originals, there was almost no change in the image output before and after passing the paper.

Further, as a result of driving in an environment of 85° C. and 85% RH, no corrosion occurred even after 500 hours.

Example 2 Two silicon films containing nitrogen atoms and oxygen atoms were deposited on thin glass.
It was attached to a photoelectric conversion element in the same manner as in Example 1 except that the film was formed to a μm thickness. The method for forming a silicon film containing nitrogen atoms and oxygen atoms is as follows.

GaX COx/S i H4=0.5N2/S
i H4=15 N Ha/S In an environment of 85% RH, corrosion occurred more slowly than the image sensor described above (corrosion occurred at 12% RH).
40 hours).

〔effect〕

By adopting the structure of the present invention, the long-term reliability of the complete contact type image sensor has been improved.

[Brief explanation of the drawing]

FIGS. 1 and 2 show a specific example of a complete contact type image sensor according to the present invention. 101.301...Transparent substrate 102...Light shielding layer 10
3...Transparent insulating layer 104...Lower metal electrode 105
．． 305... Photoelectric conversion film 106.306... Upper transparent electrode 107.307... Adhesive layer 108.308... Silicon film 109 containing nitrogen atoms
．． 309...Thin glass 110.310...Lighting window 302...Light blocking layer/lower metal electrode Figure 2

Claims (1)

[Scope of Claims] 1. In a fully contact image sensor comprising a transparent substrate, a light window and a photoelectric conversion film, and a thin glass provided above with an adhesive layer interposed therebetween, the thin glass A fully contact image sensor characterized by having a silicon film containing nitrogen atoms on the surface in contact with an adhesive layer. 2. The fully contact image sensor according to claim 1, wherein the silicon film containing nitrogen atoms further contains oxygen atoms.