JPS63316472A - One-dimensional image sensor - Google Patents

Abstract

PURPOSE:To reduce dispersions in sensitivity between respective unit sensors, by providing a common electrode and a plurality of individual electrodes disposed in a line, with a semiconductor film in between, and besides by making the common electrode positioned to be shifted slantingly above the individual electrodes. CONSTITUTION:A common electrode 4 made of a transparent conductive film does not face electrodes 11 to 14 but is disposed slantingly above them. A Cr evaporative film is first formed on an insulating substrate 2 made of glass or ceramics or the like, and it is etched into a prescribed pattern by photolithography so as to form individual electrodes 11 to 14. Next a plasma CVD method is used to form an amorphous silicon layer 3 which laminates (p), (i), (n) types in order. A metallic mask with a slit-shaped opening part is used to form the amorphous silicon layer 3, and also this mask is used to form the common electrode 4 of Al by an evaporation method. Hence, sensitivity can be prevented from being lowered and dispersed by reason that light passes through the transparent electrode before attaining to an electric generation region.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a one-dimensional image sensor such as an image reading device that reads a document and converts it into an electrical signal.

[Conventional technology]

In this type of device, there is a dense 1F image sensor that uses an image sensor that is the same size as the original, and the semiconductor film is Cd.
Devices using thin film elements such as S-based and amorphous silicon-based devices have been put into practical use. The second question is an enlarged view of the sensor part of a conventional contact type image sensor using amorphous silicon. As shown in FIG. 2 fat, a plurality of individual electrodes 11 to 14 are formed on an insulating substrate 2. These individual electrodes are made of a vapor-deposited metal thin film such as Cr, and have a pixel area of about 100 square meters and a lead-out wiring area. This individual electrode is covered with an amorphous silicon layer 3 which is laminated in the order of p-type, i-type, and n-type by plasma CVD method, etc., and is further covered with a transparent conductive film such as ITO or indium oxide. Naruko 1
An i1tr pole 40 is formed. An optical signal for projecting a same-size image of the original is made incident on the sensor having such a structure from the transparent conductive film 40 side, for example, using a Rondo lens array, etc.
By sequentially extracting the current generated on the pixel portion of the individual electrode, a time-series signal corresponding to the image on the document can be obtained.

Another example is a so-called direct-reading image sensor. FIG. 3 (18), rb+ is an enlarged view of this direct reading type image sensor. The laminated structure is the same as that of the image sensor shown in FIG. 2, but a light guide window 51.
The original is illuminated through 52 and 53, and the reflected light is directly read without using a Rondo lens.

Therefore, the insulating substrate is naturally a translucent insulating substrate 2 such as glass.
Must be 1.

Problems to be solved by invention C] Sensitivity is one of the factors that determines the characteristics of a sensor, but the second
In the structure shown in the figure, the sensitivity was kept low due to light absorption loss by the transparent conductive film 40. Furthermore, sensitivity variations from pixel to pixel often occur due to non-uniformity in the thickness of the transparent conductive film.

In the structure shown in FIG. 3, the light guide windows 51 to 5
3. After forming up to the transparent conductive film 4o to open the amorphous silicon layer 31, the photoresist is developed into a desired pattern by photolithography, and the transparent conductive film is wet-etched using an etching solution to form the amorphous silicon layer 31 individual electrodes. In general, no gas has been found that can dry-etch transparent conductive films such as ITO9 indium oxide, tin oxide, etc., and the laborious method described above is used. I have no choice but to
In addition, the reflected light from the original is transmitted through the transparent conductor 1114 of the common electrode.
Since the light enters the amorphous silicon layer 3 through 0, the drop in sensitivity and variation are exactly the same as in the case of FIG.

An object of the present invention is to eliminate the above-mentioned drawbacks, provide a one-dimensional image sensor that can be manufactured through a simple process, has good performance, and has little variation in sensitivity between unit sensors.

[Means for solving problems]

To achieve the above object, the present invention provides a one-dimensional image sensor including a common electrode and a plurality of individual electrodes arranged in a line with a semiconductor film in between, in which the common electrode is located at a position shifted from above the individual electrodes. shall exist in

[Effect]

Since the common electrode does not overlap the emission T4 region on the individual electrodes, absorption loss or variation due to the common electrode cannot occur.Also, since the light guiding window cannot be opened in the common electrode, the transparent guiding window is not overlapped with the film. Wet etching is no longer necessary,
The process becomes easier.

〔Example〕

Embodiments of the present invention will be described below with reference to figures in which parts common to those in FIGS. 2 and 3 are given the same reference numerals. 1st
In the embodiment shown in FIGS. (a) and (bl), the common electrode 4 made of a transparent conductive film is not opposed to the individual electrodes 11-14 as shown in FIG. Such an image sensor is manufactured in the following steps. First, C is deposited on an insulating substrate 2 made of glass or ceramic.
After forming the evaporated film to a thickness of 2,000 mm, it is etched into a desired pattern by photolithography to form the individual electrodes 11 to 14. Next, the electrodes are laminated in the order of 1)+I+n type using the plasma CVD method. An amorphous π silicon layer 3 is formed. In the case of p layer, silane (Silln),
EP using a mixed gas of diborane (agui) and methane (CH,), a mixed gas of SiH gas for the first layer, and a mixed gas of Sil'l*+ phosph 7 (PH3) for the n layer.
The thickness of +1+'l type layer is 500 people and 5oo respectively.
o people, 100 people.

In addition, amorphous silicon J! 3 is formed using a metal mask having a slit-like opening.Furthermore, a common electrode i4 of M is formed by a vapor deposition method using a mask in the same manner. However, in this case, the common electrode 4 is
It is necessary to align the mask so that it does not overlap with numbers 1 to 14.

Normally, the output current of the amorphous silicon diode obtained in this way is about 10 when the sensor surface illuminance is 10011x.
-" A. On the other hand, the resistivity of the n-layer formed by adding 1% P) is 101 to 10! Ω. Therefore, the current generated on the individual electrodes The voltage drop when flowing through to the common electrode is 0.01 to 0.I
It is calculated as V. In other words, when driving by applying a bias voltage of several volts between both electrodes, no problem will occur even if the common electrode is shifted.

In the example of FIG. 1, the radiation 11 Si on the individual electrodes 11-14
Since the common electrode 4 does not overlap in the area, the common i
Absorption loss or variation due to the i1 electrode cannot occur, and an opaque conductive material such as the M thin film can be used for the common electrode 4 as in the above example, so a stable t-pole can be obtained.

Figure 4 shows 1. Il! The laminated structure showing another embodiment of the present invention applied to a close-reading image sensor is the same as the embodiment shown in FIG. Light guide windows 51 to 5 opened in the center of 14
Illuminate the original through 4. To form the light guide windows 51-54, a photoresist is developed into a desired pattern by photolithography, and holes are made in the amorphous silicon layer 3 and the Cr individual electrodes 11-14 by dry etching. For amorphous silicon, a mixed gas of CF, . . . O□ is used, and for Cr, a mixed gas of ccl, . . . , o□ is used as the etching gas.

Also in this embodiment, the common type 1'j 4 is the individual electrode 11-1
Since it is out of the emission TL t'W region shown in 4, no optical absorption loss or variation due to the common electrode can occur, and the common electrode can be formed by mask vapor deposition, and wet etching of the transparent common electrode can be omitted. be.

Hereinafter, the explanation has been made using two examples, but the materials cited in the explanation are not limited to these. If the layer does not have a low resistance, the output voltage drop will be large and the desired characteristics cannot be obtained, so care must be taken.Also, when forming individual electrodes by placing an opaque common electrode on a substrate and sandwiching a semiconductor yI film, can also be applied.

〔Effect of the invention〕

In the present invention, is the common pole individual? Since it is shifted from 1tFi in a plane, there is no reduction in sensitivity or variation caused by light passing through a transparent electrode before reaching the power generation area, and dry etching is not possible in the case of a direct reading type one-dimensional image sensor. There is no need for wet patterning to form holes in the transparent conductive film, making manufacturing easier.

[Brief explanation of drawings]

FIG. 1 shows an embodiment of the present invention, +a) is a plan perspective view, fbl is a sectional view taken along the line A-A of (al), FIGS. 2 and 3 are conventional image sensors, and (Ik) are plane perspective views, Fig. 2 is a sectional view taken along the B-B plane of Fig. 2+al, Fig. 3 is a sectional view taken along the C-C plane of Fig. An example is shown, (Ml is a plane perspective view, a mountain) is t
It is a DD plane sectional view of a+. 11, 12.13.14: Individual electrode, 2: Insulating substrate,
21: Transparent insulating substrate, 3: Amorphous silicon layer, 4: Common electrode, 51.52.53.54: Light guide window. Figure 1 D Engraving of drawings C No changes to the contents) W 4th area procedural amendment (7j kalpa, September 7, 1988 3, person making the amendment d, application, address related to 'IG case) 1-1 Tanabeshinden, Kawasaki-ku, Kawasaki City Name (
Sukefuji Electric Co., Ltd. 4, Agent

Claims (1)

[Claims] 1) A one-dimensional image sensor comprising a common electrode and a plurality of individual electrodes arranged in a line with a semiconductor film in between, wherein the common electrode is located at a position shifted from above the individual electrodes.