JPH07101735B2 - Method of manufacturing image sensor - Google Patents

Description

The present invention relates to a method for manufacturing an image sensor used as an image information reading device such as an image processing device.

(Prior Art) In recent years, an image sensor using a storage photoelectric conversion element has been adopted in an image input unit of an image processing apparatus such as a facsimile or OCR.

In this image sensor, as shown in FIG. 3, a plurality of individual electrodes 2 ... Are arranged in a line on an insulating substrate 1, and lead wires 3 ... A semiconductor film 5 and a transparent common electrode 6 extending on the common electrode 4 are sequentially laminated on the electrodes 2 ...

That is, this image sensor has a configuration in which a plurality of photoelectric conversion elements are arranged in a row on the insulating substrate 1.

Next, a method of manufacturing such an image sensor will be described.

First, a metal thin film made of, for example, Al, Cr or the like is formed on the insulating substrate 1 by a vapor deposition method. After that, each individual electrode 2 ..., Lead wiring 3 ...
And a desired pattern of the common electrode 4 is simultaneously formed.

Then, a semiconductor film 5 is grown thereon by CVD (vapor phase growth) using a partial film deposition method using a metal mask so as to cover the individual electrodes 2.

Then, after this, the transparent common electrode film 6 is formed from the semiconductor film 5 to the common electrode 4 by a sputtering method using a partial film formation method or the like, and the manufacturing process of the image sensor is completed.

However, if the patterns of the semiconductor film 5 and the transparent common electrode 6 are formed by using the partial film deposition method or the like in this way, it is difficult to obtain a highly precise shape, and therefore the resolution is improved and the entire device is improved. However, there has been a problem that it is not possible to meet the recent demands such as miniaturization.

In view of these difficulties, the following image sensor manufacturing methods have been widely used.

FIG. 4 is a view showing a cross section of each step in the method of manufacturing an image sensor described below.

In this method, first, a metal thin film 8 made of, for example, Al, Cr or the like is formed on an insulating substrate 7 such as a glass plate by a vapor deposition method (FIG. 4A).

Then, a photosensitive resist resin is applied on the metal thin film 8 to form a resist layer, and a large number of individual electrodes 9, lead wirings 10 and lead wires 10 are formed on the insulating substrate 7 by an ordinary photoetching method using a desired mask. A desired pattern of the common electrode 11 is simultaneously formed (FIG. 4B).

Next, the remaining resist layer 12a is removed (see FIG.
C), and the semiconductor film 1 is formed on the entire surface of the insulating substrate 7 by the CVD method.
3 is formed (Fig. 4-D).

Next, a desired pattern of the semiconductor film 13 is formed so as to cover the individual electrodes 9 by the same photo-etching method as described above (FIG. 4E).

Next, the remaining resist layer 12b is removed, and the semiconductor film 13
A transparent common electrode film 14 is formed from the top to the common electrode 11 by a sputtering method using a partial film deposition method using a metal mask (FIG. 4F).

Thereafter, a desired pattern of the transparent common electrode film 14 is formed by the same photoetching method (see FIG.
G).

Then, the remaining resist layer 12c is removed, and the image sensor manufacturing process is completed (FIG. 4H).

By manufacturing an image sensor using such a method, it is possible to improve the planar shape accuracy of a three-layer structure portion including the individual electrode 9, the semiconductor film 13, and the transparent common electrode 14 that directly influences the characteristics of the photoelectric conversion element. In addition, the size of the entire device can be reduced.

(Problems to be Solved by the Invention) However, in such a conventional manufacturing method, since the pattern of each layer is formed by etching, a step is generated between the semiconductor film and the common electrode, and as a result, The following difficulties arise.

That is, the film thickness of the transparent common electrode deposited on the portion where the step is formed is smaller than the film thickness formed on the plane, and the increase of the resistance value or the disconnection of the transparent common electrode may occur. There is a problem that the characteristics of the photoelectric conversion element are deteriorated due to the occurrence, and the reliability of the image sensor is lowered.

The present invention is intended to solve such a problem, and reduces the variation in the film thickness of the transparent common electrode formed in the portion from the semiconductor film to the common electrode to reduce the characteristic value of the photoelectric conversion element. It is an object of the present invention to provide a method for manufacturing an image sensor, which makes it possible to manufacture stable and highly reliable products.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve this object, the present invention arranges a plurality of individual electrodes in a row and a common electrode on an insulating substrate, and a semiconductor is provided on each individual electrode. In manufacturing an image sensor in which a film and a transparent common electrode extending over the common electrode are sequentially stacked, after forming the individual electrode and the common electrode on the insulating substrate, a partial film deposition using a mask A step of depositing the semiconductor film on the individual electrodes by a method, a step of depositing a transparent electrode film on at least a portion from the semiconductor film to the common electrode, and a transparent common film by etching from the transparent electrode film. Forming a desired pattern of electrodes, and exposing the surface of the individual electrode side end portion from the semiconductor film by etching and leaving at least the common electrode side end portion and other portions. It is characterized by a step of forming a desired pattern of the semiconductor film by selectively removing the.

(Operation) In the method of manufacturing an image sensor of the present invention, a semiconductor film having a gently inclined surface at an end is formed on an individual electrode by a partial film formation method using a mask, and this semiconductor film is commonly used in a later step. Since the desired pattern of the semiconductor film is formed by selectively removing other portions by etching while leaving at least the electrode side end portion, not only it is possible to manufacture a product with high shape accuracy, but also It is possible to form a transparent common electrode having a small variation in film thickness from the semiconductor film to the common electrode, stabilize the characteristic value of the photoelectric conversion element, and manufacture a highly reliable image sensor.

(Example) Hereinafter, the Example of this invention is described in detail based on drawing.

FIG. 1 is a sectional view of each main step showing a method for manufacturing an image sensor according to an embodiment of the present invention, and FIG. 2 is a perspective view showing an image sensor manufactured by this method.

As shown in these figures, in the manufacturing method of this embodiment, first, a metal thin film 22 made of, for example, Cr and having a thickness of about 2000 Å is formed on the entire surface of an insulating substrate 21 such as a glass plate by vapor deposition ( Fig. 1-a).

After that, a photosensitive resist resin is applied to the entire surface of the metal thin film 22 to form a resist layer, and a large number of individual electrodes 23, lead wires 24, and lead wires 24 are formed on the insulating substrate 21 by a normal photoetching method using a desired mask. A desired pattern of the common electrode 25 is simultaneously formed (FIG. 1-b).

The common electrode 25 is formed on an extension line in the direction in which the individual electrodes 23 are arranged in a row, that is, at the end of the insulating substrate 21 in the longitudinal direction.

After that, the remaining resist layer 25a is removed (see FIG. 1-
c) A semiconductor film 27 having a thickness of about 2 μm made of, for example, a-Si (amorphous silicon) or the like is formed so as to cover all the individual electrodes 23 on the insulating substrate 21 by a partial film-forming method using a metal mask or the like. Formed by CVD method (Fig. 1-
d).

Then, a transparent common electrode film 28 made of, for example, ITO and having a thickness of about 800 Å is formed so as to substantially cover the semiconductor film 27 and the common electrode 25 by the sputtering method using the partial film-forming method or the like as described above ( Fig. 1-e).

Next, a metal thin film 29a made of, for example, Cr or the like and having a thickness of about 2000Å and a metal thin film 29b made of, for example, Al or the like and having a thickness of about 1 μm are partially deposited on one end of the transparent common electrode film 28 in the short side direction. Are sequentially formed by the vapor deposition method using (FIG. 1-f).

After that, by the usual photo-etching method, the desired metal thin films 28a and 28b are respectively formed from the deposited metal thin films 29a and 29b.
Patterns are sequentially formed (FIG. 1-g).

Then, after the remaining resist layer 26b is removed, the transparent common electrode film 28 is selectively removed by the same etching as above to form the desired pattern (FIG. 1-h).

Next, after removing the remaining resist layer 25c, the semiconductor film 2
A desired pattern of the semiconductor film 27 is formed by selectively removing the other portions of the semiconductor film 7 by etching, leaving the common electrode 25 side end portion (FIG. 1-i).

After that, the remaining resist layer 26d is removed to complete the image sensor manufacturing process (FIG. 1-j).

Thus, according to the method of manufacturing the image sensor of this embodiment, the semiconductor film 27 is deposited at a desired position by the partial film deposition method using a metal mask or the like, and the semiconductor film 27 is deposited in a later step.
The following effects are obtained by forming the desired pattern by selectively removing the other part of the common electrode 25 example except the end part by etching.

That is, the edge of the semiconductor film 27 formed by the partial film formation method using the metal mask described above has a gently inclined cross section, which is formed between the semiconductor film 27 and the common electrode 25. This is a preferable condition for reducing the variation in the film thickness of the transparent common electrode 28.

Therefore, such an inclined cross section is formed only at the end portion of the semiconductor film 27 on the common electrode 25 side, and the other end portion, that is, the end portion in the short side direction in the image sensor of this embodiment is etched to have a desired pattern. By forming
It is possible to form a plurality of photoelectric conversion elements having a stable effective plane shape and area, and to prevent the increase of the resistance value, disconnection, etc., and further stabilize the characteristics of the photoelectric conversion elements.

In this embodiment, the individual electrode 23 and the common electrode
I explained about 25 using Cr as the material,
The present invention is not limited to this, and for example, Ti or the like may be used. The semiconductor film 27 is not limited to the a-Si film, but may be, for example, a-Si / a-si (x).
The present invention can be similarly applied to a multilayer structure film such as C (1-x).

Further, it goes without saying that a photoelectric conversion element group of two or more rows may be simultaneously formed by the manufacturing method of the present invention and then a plurality of image sensors may be manufactured by cutting.

As described above, according to the present invention, the characteristic value of the photoelectric conversion element can be reduced by reducing the variation in the film thickness of the transparent common electrode formed in the portion from the semiconductor film to the common electrode. A stable and reliable product can be manufactured.

[Brief description of drawings]

FIG. 1 is a sectional view of each step for explaining a method of manufacturing an image sensor according to an embodiment of the present invention, FIG. 2 is a perspective view showing the image sensor, and FIG. 3 is a perspective view showing a conventional image sensor. FIG. 4 and FIG. 4 are cross-sectional views for each step for explaining a conventional method of manufacturing an image sensor. 21 …… Insulating substrate 23 …… Individual electrode 25 …… Common electrode 27 …… Semiconductor film 28 …… Transparent common electrode

Claims (1)

[Claims] 1. An image sensor in which a plurality of individual electrodes are arranged in a row on an insulating substrate and a common electrode is provided, and a semiconductor film and a transparent common electrode extending on the common electrode are sequentially laminated on each individual electrode. In manufacturing the above, after forming the individual electrodes and the common electrode on the insulating substrate, depositing the semiconductor film on the individual electrodes by a partial deposition method using a mask, and at least the semiconductor film A step of depositing a transparent electrode film on a portion from above to the common electrode; a step of forming a desired pattern of the transparent common electrode by etching from the transparent electrode film; and an individual electrode side by etching from the semiconductor film. A desired pattern of the semiconductor film is formed by exposing the upper surface of the end portion and selectively removing the other portion leaving at least the end portion on the common electrode side. An image sensor manufacturing method, comprising: