JPS59204267A - Thin film reading device - Google Patents

Abstract

PURPOSE:To restrain the generation of defective bits by putting the titled device in a homogeneous and excellent layer structure by a method wherein a photoconductor layer surrounded by the first and second electrodes is formed flatly. CONSTITUTION:The titled device is composed of a Cr electrode 2 formed from the side of one long side of the surface of a glass substrate 1, an amorphous Si hydrogenated layer 3 so formed as to cross the electrode 2 at a position slightly backward from the tip of this electrode 2, an Si oxide layer 4 formed onto the substrate while forming a slight super-position on this layer 3, and a common clear electrode 5 made of Ind-Sn oxide film formed in comb-shape so as to be opposed to the Cr electrode via layer 3. Besides, the width of this clear electrode is formed smaller than the width of the Cr electrode.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a thin film reading device, and more particularly to a long thin film reading device having a sandwich structure used in image sensors and the like.

<Prior art> Conventionally, semiconductor image sensors such as C0D1 photodiode arrays have been the main source of document reading devices used in input sections of facsimile machines, etc., but these devices usually use small optical systems. Therefore, the optical path length is long, which is a reason that prevents miniaturization of the mounting device.

Recently, in order to reduce the size of the device, a long thin film reader having a sandwich structure in which amorphous silicon as a photoconductor is sandwiched between a metal electrode and a transparent electrode has been proposed.

As shown in FIG. 1 as a plan view and as shown in FIG. 2 as a cross-sectional view taken along line A-A in FIG. metal electrodes 2, an amorphous silicon layer 3 formed so as to cover these metal electrodes 2, and a transparent electrode 5 integrally formed over the entire surface of the amorphous silicon layer 3. It is composed of

In this long thin film reading device, usually an insulating substrate 1
After depositing a thin film of aluminum (A), chromium (Cr), gold (Au), etc. on top, a metal electrode 2 with a film thickness of several hundred to several thousand angstroms (X) is formed using photolithography or the like. is formed, and then an amorphous silicon layer is deposited by vapor deposition, plasma pyrolysis growth (plasma CVD), sintering method, or the like.

However, this amorphous silicon layer becomes partially thinner or has a weaker film quality at the step part at the end of the lower metal electrode 2, so it is difficult to apply a voltage between the metal electrode and the upper transparent electrode. However, due to leakage caused by pinholes or the like, dielectric breakdown occurs at this stepped portion, which tends to cause defective bits. Additionally, in order to prevent this, a method has been considered in which the film thickness of the metal electrode 2 is reduced to reduce the step difference, but with this method, defects such as disconnections and pinholes are likely to occur in the metal electrode itself. There was a drawback.

<Object of the Invention> The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a highly reliable thin film reading device with a low incidence of defective bits.

<Structure of the Invention> The present invention provides a thin hr tj/n removing device having a sand char structure in which a photoconductor layer is sandwiched between a first electrode and a second electrode formed in a predetermined pattern on a substrate.
The photoconductor layer is formed slightly away from the tip of the first electrode, and an insulating layer is formed on the remaining portion in front, and the second ion pole is written as 1-1IJ, and 1 quasi-pole is formed. By setering the photoconductor layer so that it has a smaller width than the electrode width, the photoconductor layer in the center area, that is, the area surrounded by the first electrode and the second electrode, is This is intended to prevent leakage caused by pinholes or the like in the photoconductor layer by preventing the electrode from crossing the step.

Key I is commonly used as the first electrode that is initially formed on the substrate.
A metal electrode is used, and a transparent electrode is used as the second layer +Th formed thereon via a photoconductor layer that is subsequently formed.

In a special case where light is irradiated from the substrate side, a transparent electrode is used as the first electrode, and a metal electrode or the like is used as the second electrode. In either case, by determining the shapes of the light guide/casing layer and the second electrode in accordance with the shape of the first electrode formed on the substrate, it is possible to eliminate the difference in level due to the shape of the first electrode. This is intended to prevent uneven portions of the film appearing on the photoconductor layer formed thereon from being included in the sensor section.

<Example> Next, a long thin film reading device according to an example of the present invention will be described with reference to the drawings.

As shown in FIG. 3 as a plan view and as shown in FIG. A number of chromium (Cr) electrodes 2 formed in a shape, and an amorphous silicon hydride layer 3 formed across the chromium electrode 2 at a position slightly set back from the tip of the chromium electrode 2. Then, while forming a slight overlapping portion on this amorphous hydrogenated silicon layer 3, the silicon oxide layer 4 formed over the substrate and the side facing the long side on which the chromium electrode is formed are formed. A common transparent layer made of indium tin oxide +1&1 (ITOH'A) formed in a comb shape so as to face each of the chromium electrodes from the long side with the amorphous silicon hydride layer 3 interposed therebetween. It is composed of an electrode 5.

The width of this transparent electrode is smaller than that of the chromium electrode.

Next, a method of manufacturing a long thin film reading device according to an embodiment of the present invention will be explained.

First, a 3000 angstrom (X) thin chromium film is deposited on an insulating glass substrate 1 by electron beam evaporation, and a plurality of chromium electrodes each having a sensor portion corresponding to a bit are formed by photolithography. Form.

Next, a metal jig formed into a predetermined shape is placed in close contact with a predetermined position on the substrate surface, and using this as a mask, the amorphous silicon hydride layer 3 is formed on the chromium electrode 2 by plasma pyrolysis. The membrane is band-shaped, slightly receding from the tip. The gas used at this time is monosilane (SiH
4) Under the following conditions, a substrate temperature of 250°C, a discharge pressure of 0.4 Torr, a distance between the cage electrode and the substrate of 40 mm, a high frequency power of 20 W, a gas flow rate of 20 standard cc min (SCCM), and a non-conductor of approximately 1 μm. A crystalline hydrogenated silicon layer 3 is formed.

Furthermore, a gold jig 4y formed into a predetermined shape is placed in close contact with a predetermined position on the substrate surface, and using this as a mask, a silicon oxide (SiO2') film 4 is formed by plasma pyrolysis.
is formed so as to slightly overlap the amorphous hydrogenated silicon layer 3. The gas used at this time is monosil/(
5xH4) Deca oxide (N20) mixed gas, substrate temperature 250℃, discharge pressure IToor, electrode-to-substrate distance 40mm, high frequency power 100W, gas flow rate 5
5 under the conditions of iH45SCCM, N20250 SCCM
A film is deposited to a thickness of 000X.

Finally, as a transparent electrode 5, an I2To thin film is deposited at 800X on the entire surface by DC sputtering. A comb-shaped transparent electrode 5 is then formed by photolithography.

The DC voltage-current characteristic f of the elongated thin film reader thus formed is shown in FIG. Here, the vertical axis is the current (A
/ctn2), and the horizontal axis is the bias voltage (V). A is a characteristic curve of photocurrent when irradiated with light of 100 lux (1 lux), Bi''l is a characteristic curve of dark current.

As is clear from the figure, the light [(+, current is 105 of the dark current
It has good characteristics as it is double sided.

In addition, the amorphous hydrogenated silicon layer is flat without any step in the sensor part, that is, the part sandwiched between the chromium electrode and the transparent electrode, and an insulating layer is interposed in the step part at the tip of the chromium electrode. Because of this, when reading a long thin film with 4=1, there will be no defective bits due to leakage caused by the thinning of the layer on the step or the formation of pinholes, resulting in excellent reliability. .

In the embodiment, the printed silicon film 4 as an insulating film is formed so as to slightly overlap the amorphous hydrogenated silicon layer 3-H.
However, it goes without saying that if the cross-sections at the boundary portions are formed in close contact with each other, it is not necessary to form nine parts.

As an insulating film, in addition to the silicon film in the example,
Silicon nitrideff'A, PSG phosph.

It is also possible to use polyimide resin (5ilicate glass), etc.

Furthermore, in the embodiment, a configuration in which light is irradiated from above has been described, but when light is irradiated from the lower substrate side, a translucent insulating substrate is used and the first electrode is a transparent electrode. The second ′′ tail electrode may be a metal′ electrode.

<Effects> As explained above, according to the present invention, in the sensor section, that is, in the effective part of the photoconductor core layer surrounded by the first electrode and the second electrode, the photoconductor Since the layers are formed flat, a homogeneous and good layer structure and the occurrence of defects and defective pits are suppressed, thereby providing a highly reliable thin J conversion reading device ρ.

[Brief explanation of the drawing]

The first item 1 is a plan view of a conventional long thin film reader;
The figures are a sectional view taken along the line AA in FIG. The figure shows the current of a long thin film reader according to an embodiment of the present invention.
FIG. 3 is a diagram showing voltage characteristics. l... Insulating substrate, 2... Metal electrode, 3... Optical monument layer, 4... Insulator layer, 5... Transparent electrode, A...
Characteristic curve of light'rI-5 current, B...Characteristic curve of dark current. Figure 3 Figure 4 (V)

Claims (2)

[Claims] (1) A plurality of first electrodes formed on an insulating substrate, a photoconductor layer formed on the first electrodes with the tip of the first electrodes slightly recessed, and a photoconductor layer formed on the first electrodes, an insulating layer formed adjacent to the photoconductor layer and covering at least the tip of the first electrode; and a comb-shaped second electrode having a small electrode width. (2) The insulating layer is located at the tip of the photoconductor layer.