JPS639969A - Adhesion type image sensor and manufacture thereof - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an image sensor, and particularly to a contact type image sensor for reading an information carrier, such as a document, at the same magnification.

(Prior Art) Contact image sensors of various structures have been proposed, which are incorporated into devices such as facsimile machines and image scanners, and are capable of reading documents at the same magnification. This close-contact image sensor generally has a large number of light-receiving parts arranged in an array to receive reflected light from the document, for example, so that the size is the same as the width of the document, and there is no need for a reduction optical system. Therefore, it has features such as being able to downsize the device. In addition, hydrogenated amorphous silicon (hydrogenated amorphous silicon), which can be uniformly formed over a large area by a low-temperature process (temperature of 200 to 300°C), is used as the photosensitive layer of the light receiving part.
Hereinafter, it may be abbreviated as a-3t:H. ) is currently being researched and developed.

In such a contact type image sensor, in order to read a document with high resolution, it is necessary to bring the document and the light receiving section into close contact with each other. On the other hand, in order to read a document, it is necessary to irradiate the document with light by some method and have a light receiving section receive the reflected light from the document. Therefore, it is important to consider how to irradiate (inject) the light from the light source onto the document.

Hereinafter, such a method will be explained with reference to the drawings.

Figure 4 shows, for example, the conventional technology disclosed in the literature (``Complete contact type amorphous silicon image sensor'' Electrophotography Society Symposium (How far have amorphous silicon devices come?) Proceedings, May 24, 1985, p. 53-56). FIG. 2 is an explanatory diagram showing an example of a contact type image sensor. The light receiving section 13 provided on the glass substrate 11 has a photosensitive layer 15 a-3i: H11J15 connected to the common electrode 17.
It has a sandwich-type structure sandwiched between the electrode 19 and the individual electrode 19. Desired area of rIA optical layer 15 (light transmission window 2
The common electrode 17 in contact with the photosensitive layer 15 completely shields light from light except for 1 part). Further, an original 23 is installed on the opposite side of the glass substrate 11 from the light-receiving section 13, and there is a height of, for example, 7 to 8 cm between the glass substrate 11 and the original 23.
A rod lens array 25 of about mm is provided.

Further, a gap is provided between the rod lens array 25, the glass substrate 11, and the original 23 for converging light, and a gap is provided near the rod lens array z5 for irradiating the original with light. Two light sources are provided. Therefore, according to this image sensor, the original 23
information can be guided to the light receiving section 13 on a one-to-one basis.

Further, FIG. 5 is an explanatory diagram of another example of the conventional contact type image sensor disclosed in the same document, and shows an example in which a rod lens array is unnecessary. The basic structure of the light receiving section 13 of this image sensor is a sandwich type similar to that shown in FIG. 21
is provided, and is configured to guide light from a light source 27 provided on the opposite side of the glass substrate 11 to the side on which the light receiving section 13 is provided to the original 23 through this window 21 to illuminate the original. Furthermore, on this light receiving section 13, there is a
A light-transmitting insulating film 29 with a thickness of about several μm is provided as shown in FIG. By maintaining the distance, the amount of reflected light from the document received by the light receiving section was increased.

(Problems to be Solved by the Invention) However, the conventional contact type image sensor using a rod lens array has a problem in that the size of the contact type image sensor becomes large due to the provision of the rod lens array. there were. Furthermore, there is a problem in that the contact type image sensor becomes more expensive due to the use of this rod lens array.

In addition, in the case of a conventional contact image sensor that has a structure in which a window is provided in the light receiving part on the substrate through which light from a light source provided on the underside of the substrate can be introduced, a -St: In order to form a light transmission window by etching a part of the H layer, a-St
: There was a problem in that current easily leaked from the end of the H layer, that is, from the inner wall surface of the light transmission window. The cause of this is C.
It is considered that the end face of the a-St:) layer is damaged during plasma etching performed in an active gas such as F4, or residual impurities are attached to this end face.

Further, for example, in order to efficiently extract photocurrent, it is preferable to form the individual electrodes 19 up to the light transmitting window 21 of the photosensitive layer 15; The problem is that it is necessary to perform manufacturing while aligning the common electrode 17 with high precision so that there is no short circuit between the common electrode 17 and the individual electrodes through the light transmission window provided in the photosensitive layer. was there. Therefore, this causes an increase in manufacturing cost and a decrease in manufacturing yield.

Furthermore, since the portion of the light-transmitting insulating film 29 provided on the light-receiving portion 13 corresponding to the light-transmitting window 21 (the portion indicated by 29a in FIG. 5) is in a concave state, dust tends to accumulate in this portion.
Therefore, there is a problem in that it becomes a cause of malfunction of the image sensor.

The object of the first invention of this application is to solve the above-mentioned problems and provide a fully contact type image sensor having high resolution.

A second object of the invention of this application is to provide a method for easily manufacturing a fully contact type image sensor having high resolution.

(Means for solving the problem) In order to achieve this object, according to the first invention of this application, a common electrode, a photosensitive layer and individual electrodes are provided on a transparent substrate, and light from the transparent substrate side is provided. In a contact image sensor in which light is incident on an information carrier through a light-transmitting window provided in the above-mentioned photosensitive layer and reflected light from this information carrier is detected by the above-mentioned photosensitive layer, the above-mentioned light-transmitting window is provided with the above-mentioned photosensitive layer. It is characterized by comprising a transparent insulating layer that is flush with the surface of the layer.

According to the second invention of this application, a common electrode is provided on a transparent substrate;
A contact type comprising a photosensitive layer and individual electrodes, in which light from the transparent substrate side is incident on the information carrier through a light transmission window provided in the photosensitive layer, and reflected light from the information carrier is detected by the photosensitive layer. The method for manufacturing an image sensor includes the steps of forming an island-shaped transparent insulating layer on the above-mentioned transparent substrate, and closely adhering a photosensitive layer around the above-mentioned island-like transparent insulating layer on the above-mentioned substrate. It is characterized by including the step of forming.

In carrying out the second invention, it is preferable to form the surface of the photosensitive layer so as to be flush with the surface of the island-shaped transparent insulating layer.

(Function) According to the configuration of the first invention described above, the transparent insulating layer functions as a window for light transmission, and the surfaces of the photosensitive layer and the transparent insulating layer are substantially flat and continuous. Become.

Therefore, individual electrodes can be formed over the surfaces of both these layers using, for example, a transparent conductive film, and furthermore, the surfaces of layers formed on such flat surfaces, such as individual electrodes and protective layers, are also flat. It becomes a surface.

According to the configuration of the second invention described above, after the island-like transparent insulating layer is formed, the photosensitive layer is formed in close contact with the periphery of the island-like transparent insulating layer, so that the ends of the photosensitive layer are protected by the transparent insulating layer. It turns out.

Further, since the individual electrodes can be formed after covering the common electrode with the photosensitive layer and the transparent insulating layer, short circuits between the common electrode and the individual electrodes will not occur.

Furthermore, the alignment accuracy required when forming individual electrodes is relaxed.

(Embodiments) Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 3. It should be noted that these figures are only schematic representations to the extent that this invention can be understood, and the dimensions of each component,
The shape and arrangement relationship are not limited to the illustrated example.

In each figure, the same components are designated by the same reference numerals. In addition, the same components as in the prior art are denoted by the same reference numerals.

FIG. 1(A) is a partial cross-sectional view showing a contact type image sensor of the present invention focusing on one light-receiving part, and FIG. 1(B) is a partial plan view showing this image sensor as seen from the document side. It is. Note that, in order to avoid complicating the drawing, FIG. 1(A) is shown with some hatchings indicating the cross section omitted.

In these figures, 11 indicates a transparent insulating substrate such as glass. In this embodiment, this glass substrate 11
A common electrode 17 is provided on the top of the common electrode 17, which has a light-transmitting window 21 obtained by removing a portion of a metal layer having a light-shielding property, such as chromium or nichrome, and which also serves as a light-shielding film. Further, on the area of the glass substrate 11 corresponding to the light transmission window 21, a transparent insulating layer 31 made of, for example, 5in2, SiNx, etc.
is the provision.

Further, on the common electrode 17 and in the area surrounding this transparent insulating layer 31, a photosensitive layer 15, for example, an a-3t:H layer 1 is formed.
5 is provided so as to be flush with and in close contact with the surface of the transparent insulating layer 31.

Further, individual electrodes 19 made of a transparent conductive film such as an ITO film are provided over both surfaces of the photosensitive layer 15 and the transparent insulating layer 31.

Therefore, the light-receiving section 13 can be configured such that the light-transmitting window 21 of the photosensitive layer 15 is provided with a transparent insulating layer, and the photosensitive layer 15 is sandwiched between the common electrode 17 and the individual electrodes 19.

Furthermore, a transparent insulating film 29 which also serves as a protective film for the light receiving section 13 is provided on the glass substrate 11 containing the light receiving section 13, as in the conventional case.

The contact type image sensor having such a structure can be used in close contact with the original 23 with the light-transmitting insulating film (protective film) 29 interposed therebetween. Then, light emitted from a light source 27 provided below the glass substrate 11 passes through the glass substrate 11, the transparent insulating layer 31, etc., and enters the original 27, and the source of this light yI2
The reflected light from 7 is received by the light receiving section 13 and converted into an electrical signal.

Next, a method for manufacturing a contact type image sensor according to the present invention will be explained with reference to FIGS. 2(A) to 2(D), FIG. 3, and FIG. 1.

First, a chromium thin film was formed on the glass substrate 11 by a suitable method such as vacuum evaporation. Subsequently, a light transmitting window was formed in a predetermined area of this thin chromium film using photolithography and etching techniques, thereby obtaining a common electrode 17 which also served as a light shielding film and had a light transmitting window 21 in a portion ( Second
(See figure (A)).

Next, by a suitable method such as plasma CVD method, for example, Si
02 was formed, and then a resist pattern 33 was formed to cover the area corresponding to the above-mentioned light transmission window 21 of this 5 inch 2 and the area other than the area where the photosensitive layer is to be formed. In addition, the resist in this case is used for the photosensitive layer a-
5t: ) (This is a high temperature resist that can withstand the film formation temperature of the layer.

Subsequently, using this resist pattern 33 as a mask, the exposed portion of the Sin was removed to form an island-shaped transparent insulating layer 31 (see FIG. 2(B)).

Next, for example, an a-Si:H layer 35 for forming the photosensitive layer 15 was formed on the glass substrate 11 including the island-shaped transparent insulating layer 31 and the resist pattern 33. In this embodiment, this a-3i:H layer 35 is replaced by this a-Si:H layer 3.
5, the surface of the portion formed on the common electrode 17 was formed at the same level as the surface of the transparent insulating layer 31 (
(See Figure 2(C)).

Subsequently, the resist layer constituting the resist pattern 33 is dissolved using a solvent, and a-3t on this resist layer is dissolved.
: The H layer 35 was removed (lifted off). In this way, the photosensitive layer 15 could be formed in close contact with the island-shaped transparent insulating layer 31 on the upper side of the glass substrate 11 (
(See Figure 2 (D)).

Next, a transparent conductive film made of an ITO film is formed on the photosensitive layer 15 and the transparent insulating film 31 by a suitable method such as sputtering or evaporation, and then this transparent conductive film is processed into a predetermined shape to form individual pieces. Electrodes 19 were formed. Further, a protective film 29 of, for example, Si is formed on the glass substrate 11 including the individual electrodes 19 by a suitable method such as a plasma CVD method.
n, or SiN.

A contact type image sensor of the present invention as shown in FIG. 1 could be obtained by forming the following.

In the above embodiment of the manufacturing method, the formation of the photosensitive layer 15 was explained using the lift-off method, but the manufacturing method of the present invention is not limited to this. For example, in the step explained using FIG. 2(B), the resist pattern 33 is removed after finishing the patterning of Sin, and then the a-St:H layer is placed on the glass substrate 11 including the transparent insulating film 31. form 35. Next, as shown in FIG. 3, a resist pattern 37 is formed to cover the area where the photosensitive layer is to be formed, and using this resist pattern 37 as a mask, unnecessary portions of the a-3t:H layer 35 are removed and exposed to light. A layer 15 may also be formed.

In addition, the materials and means such as the film forming method used in the production described in each of the above embodiments are not limited to those described in the embodiments, and other suitable materials and means may be used.

(Effects of the Invention) As is clear from the above description, according to the contact type image sensor of the present invention, by providing the transparent insulating layer in the light transmission window so as to be flush with the surface of the photosensitive layer, Layered electrodes can be formed over the surfaces of both of these layers, and a protective film having a flat surface without recesses can also be formed on these individual electrodes. Therefore, it is possible to prevent insufficient light quantity or defective light reception caused by accumulation of dust as in the conventional case.

Furthermore, according to the method for manufacturing a contact image sensor of the present invention, the photosensitive layer can be formed without etching and the edges of the photosensitive layer are protected by the transparent insulating layer, thereby preventing damage during formation. It is possible to prevent leakage current from occurring due to contamination or the like.

Furthermore, since individual electrodes can be formed on the surfaces of both layers after covering the common electrode with a photosensitive layer and a transparent insulating layer, short circuits between the common electrode and the individual electrodes will not occur.
Therefore, individual electrodes that can efficiently obtain a photocurrent can be formed with a looser alignment precision than in the past, so that manufacturing yield can be improved.

Therefore, it is possible to provide a fully contact image sensor with high resolution and a method for manufacturing the same.

[Brief explanation of drawings]

FIGS. 1(A) and (B) are a sectional view and a plan view showing an embodiment of the contact type image sensor of the present invention, and FIGS. 2(A) to (D) are manufacturing of the contact type image sensor of the present invention. FIG. 3 is an explanatory diagram showing another manufacturing method of the contact type image sensor of the present invention, and FIGS. 4 and 5 are explanatory diagrams of a conventional contact type image sensor. 11... Transparent substrate, 13... Light receiving section 15.
...Photosensitive layer, 17...Common electrode 19...
Layered electrodes, 21...Light transmission window 23...Information carrier (original) 27...Light source 29-...Transparent insulating film (protective film) 31...Transparent insulating layer 33.37. ...Resist pattern 35...a-3i: H layer. Patent applicant: Oki Electric Industry Co., Ltd.
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Claims (3)

[Claims] (1) A common electrode, a photosensitive layer, and individual electrodes are provided on a transparent substrate, and light from the transparent substrate side is incident on an information carrier through a light transmission window provided in the photosensitive layer, and reflected light from the information carrier. A close-contact image sensor that detects an image using the photosensitive layer, wherein the light-transmitting window includes a transparent insulating layer that is flush with the surface of the photosensitive layer. (2) A common electrode, a photosensitive layer, and individual electrodes are provided on a transparent substrate, and light from the transparent substrate side is incident on an information carrier through a light transmission window provided in the photosensitive layer, and reflected light from the information carrier. In manufacturing a contact-type image sensor that detects with the photosensitive layer, a step of forming an island-shaped transparent insulation layer on the upper side of the transparent substrate, and a step of forming an island-shaped transparent insulation layer on the upper side of the substrate and around the island-shaped transparent insulation layer. 1. A method for manufacturing a contact image sensor, comprising the step of forming a photosensitive layer in close contact with each other. (3) The method of manufacturing a contact image sensor according to claim 2, wherein the surface of the photosensitive layer is formed to be flush with the surface of the island-shaped transparent insulating layer.