JPS63110771A - Contact-type image sensor - Google Patents

Abstract

PURPOSE:To execute the manufacture in a simple process without deteriorating the yield rate of a product and to reduce the irregularity of a photoelectric output at each photoelectric transducer in such a way that an individual electrode is formed by a conductive film which comes into contact with the area which is equal to a semiconductor layer at an opening of an insulating film. CONSTITUTION:A group of 1728 conductive films 7 which concurrently function as 100mum wide stripe-like individual electrodes arranged at an interval of 25 mum starting from an ITO film and as a wiring part are formed on a glass substrate 1 by photoetching; photosensitive polyimide is coated to form an insulating film 8; a 100mum wide opening 9 is formed by means of a mask which is aligned by an end-pin mating method. In addition, a high-resistance P-type a-SiC film, an I-quality a-Si film and an N-type a-Si film are piled up in succession by means of a mask and by a plasma glow discharge method; a semiconductor layer 4 is formed; a 1mm wide common electrode 5 is formed on the layer by a carbon paste using a screen-printing process.

Description

[Detailed description of the invention] [Technical field to which the invention pertains]

The present invention relates to a close-contact image sensor in which a large number of photoelectric conversion elements are arranged in a line, and is used in a facsimile document reading outfit ff, an OA equipment image-powered device 1 banknote validator, a hand scanner, and the like.

[Prior art and its problems]

As a practical example of a contact type image sensor, 8 dots/am
A document reading device for facsimile is known. Figure 2 (a), ~) shows a practical example of this, which is an insulating substrate I
Individual 11 consisting of wA3 and chrome on top! I! li!
2. After processing the connection portion 21 and the connection portion 51 of the common electrode by photoetching, a photoelectric conversion semiconductor layer 4 made of a 1M amorphous silicon film (hereinafter referred to as a-3i) is grown using a mask, and further a-3i is formed.
The ITo film 1111 forming a heterojunction with the film 4 is formed by masking the pole 5. In this image sensor, since the common a-pole is formed using a mask, the distance X in FIG. 2 varies. Since the portion sandwiched between the chromium film 21 and the ITO film 5 also plays the role of a light receiving element, variations in X result in variations in the photoelectric conversion area, resulting in variations in photoelectric output, leading to deterioration in image reading quality and yield. There was a drawback. In order to reduce this variation in X, there are problems in that an expensive device for positioning is required and that the manufacturing process is expensive because it takes extra time. Another practical example is a contact type image sensor shown in FIG. On an insulating substrate 1, individual electrodes 2 and their connection parts 21 are made of chromium, and wiring 3 is made of chromium-gold.
and P wet hydrogenated amorphous silicon carbide (hereinafter a-5
iC), Ifa-3l, and N-type a-3t are sequentially deposited to form a pin junction photoelectric conversion layer 4. ITO common electrode 5
After forming a film using a mask, a chromium light shielding layer 1!16 was processed by photoetching. However, when the chromium light-shielding film 6 formed in this manner is processed by photoetching in order to define the pixel area, the light guide window is required to have high positional accuracy. For example, for an 8 dot/fl sensor, the individual electrodes 2 are 100 n square,
Since the light guiding window is approximately 60 to 100 n square, the position accuracy is ±
20- or less is required. For large 1&temporary sensors with a width equal to tens of values of originals, such as contact type sensors, it is extremely difficult to achieve a position accuracy of ±20n or less, and when photo-etching a light-shielding film, it is necessary to align the markers using at least a microscope. Other processes also cause dimensional variations such as shrinkage of the substrate, so advanced production technology is required and the process is expensive.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a contact-type image sensor that can be manufactured in a simple process without reducing the yield of the product, and has small variations in the photoelectric output of each photoelectric conversion element, while eliminating the above-mentioned drawbacks.

[Key points of the invention]

The present invention includes a common electrode extending in one direction on one side of a photoelectric conversion semiconductor layer, an insulating film provided on the other side with a strip-shaped opening extending in the direction, and an insulating film provided on the common electrode extending in the same direction. A conductive film that is in contact with the semiconductor layer at the opening of the insulating film and has a plurality of strip-shaped conductive films of equal width extending at equal intervals in a direction perpendicular to the said direction, and that is in contact with the semiconductor layer in an equal area at the opening of the insulating film. form individual electrodes, and between the individual electrodes and the common electrode, all pixels of the photoelectric conversion element have the same area. In this case, the positional accuracy of the opening of the insulating film and the conductive film group does not need to be high, and processing can be performed by a simple process such as end face alignment even in a photolithography process. Note that in order to prevent the output of a pixel from being influenced by adjacent pixels, it is desirable that at least the layer portion of the semiconductor layer on the side that contacts the conductive film group is made of a high-resistance semiconductor film.

[Embodiments of the invention]

Part 2 below. Embodiments of the present invention will be described with reference to drawings in which parts common to those in FIG. 3 are given the same reference numerals. FIG. 1 fat, e+ shows an embodiment of the present invention, and ta+
1 is a cross-sectional view, and middle) is a plan view showing the positional relationship between the two poles and the insulating film.
As shown in FIG. 1), the TO film 7 has a width of 1
00 tna with a spacing d of 25 fa. On this is formed an insulating film 8 having an opening 9 in a strip shape perpendicular to the strip ITO film 7 and having a width of 100 nm, for example. ITO in the shaded area 10 in Figure 1 of Part 9)
It is in contact with the membrane 7. As shown by the dotted line in Figure 1),
A common pole 5 covering the opening 9 is formed. Such an image sensor was manufactured through the following steps. First, on a glass substrate 1, a group of 1,728 conductive films 7, which served as individual electrodes and wiring, were processed from an ITO film by photoetching, each having a width of 100 nm and an interval of 25 cm. Further, a photosensitive polyimide such as Hitachi Chemical IPL-1200 was deposited to form an insulating film 8, and an opening 9 having a width of 100 tna was formed using a mask aligned by the end face alignment method. Furthermore, a high-resistance P-type a-SIC film with a thickness of 200 mm, 5 it (* , 'I quality A-5T film with a thickness of 5000, and further 5i
A 500mm thick N-type a-
A semiconductor layer is formed by sequentially depositing 5iJI using a mask, and a common 1! The plate 5 was formed to have a width of 1 fi by screen printing with carbon paste, for example, Dotite PC-40LP manufactured by Fujikura Kasei. Figure 1 (X shown in bl)
+7 are each designed to be 300μ. As a result of manufacturing 500 contact type image sensors in this way, the dimensional variation in X was 300-±40μ, and the dimensional variation in y was 30Opa±43μ. Further, a typical V-1 characteristic of the element at this time is shown in FIG. 4, which shows the output current when a reverse bias of 251x, 2.5 lx, and dark time is applied. In addition, for one sensor, for an applied voltage of 3 V, 25
When the output current when irradiated with 1.chi. light was measured for 1728 elements, the average value was within -6.4%. Furthermore, Figure 5 shows the results of a similar investigation of variations in element output for 500 prototype sensors.
All 500 sensors had element outputs within ±20%, of which 483 had outputs within ±10% (96.6%).
)there were. FIGS. 6(a) and 6(bl) show another embodiment of the present invention, and (
a). fbl is a sectional view and a plan view similar to those in FIG. 1. In this embodiment, a common electrode 8i5 made of chromium is provided on a glass substrate l as shown by the dotted line in FIG. 8 is formed, and the strip-shaped ITOTlO2 is formed in the opening 9.
It is formed on the semiconductor layer 4 at right angles to the length direction thereof, and contacts the semiconductor layer 4 at the opening 9 to form a heterojunction. Such an image sensor first forms a common electrode 5 by depositing a chromium film on a glass substrate 1 using a mask, and then! After forming a high quality a-5L film 4 to a thickness of 1-Hz using a plasma glow discharge method using a mixed gas of 5IHa and H2 using a mask, an insulating film 8 was formed from a silicon nitride film, and photoetching was performed to achieve a high "100" openings 9 were obtained.Furthermore, the ITO film formed by sputtering was processed by photoetching using a mask with end face pinning to form 1,728 strip-shaped individual electrodes and alternatingly different directions. A wiring group 7 of L-100g and d-25- was formed to be drawn out to. In this case, the wiring group 7 of FIG. As a result of prototyping 500 contact image sensors similar to the example shown in , the dimensional variation in xI+x2 was 100 tna±42n, the dimensional variation in y was 200 tna±48-, and the applied voltage for the 500 sensors was When the output of each of the 1728 elements was measured at an irradiation intensity of 251x with respect to 5V to determine the variation, a distribution as shown in FIG. 7 was obtained, and all variations were within ±30%.

【Effect of the invention】

According to the present invention, one side of the photoelectric conversion half-layer has a dimensional accuracy of 9
A group of parallel conductive films with a constant width that are in contact with a common electrode with poor positional accuracy and laminated on the other side with an insulating film interposed therebetween are all equal in the strip-shaped opening of a constant width in the insulating film that intersects them at right angles. Contact by area and individual 1! By making the other part of the conductive film also serve as the lead-out wiring, the variation in photoelectric output is extremely small, and the processing of each film requires expensive equipment and long time to align markers, resulting in high costs. A contact image sensor that can be manufactured without requiring the steps described above can be obtained.

[Brief explanation of the drawing]

FIG. 1 shows an embodiment of the present invention, and fa) is a sectional view. Fig. 2 is a cross-sectional view of a conventional practical example, Fig. 3 is a cross-sectional view of another conventional practical example, and Fig. 4 is a plan view showing the positional relationship between both electrodes and the insulating film. FIG. 5 is a frequency distribution diagram of the element output in the sensor of the embodiment shown in FIG. 1, and FIG. Another example is shown, (al
is a cross-sectional view, (bl is a plan view showing the positional relationship between both electrodes and the insulating film, and FIG. 7 is a frequency distribution diagram of the element output in the sensor of the embodiment shown in FIG. 6. 1: Insulating substrate, 4: Photoelectric conversion semiconductor layer, 5: Common electrode,
7: [TO film, 8: Insulating film, 9: Opening, 10: Contact region. The patent attorney +/- 11JO is done in one go. Figure 2/~1 Figure 4 1.

Claims (1)

[Scope of Claims] 1) A common electrode extending in one direction on one side of a photoelectric conversion semiconductor layer, an insulating film provided on the other side with a striped opening extending in the direction, and the insulating film. A close-contact image, comprising: a plurality of strip-shaped conductive films having equal widths, provided on top of the semiconductor layer, contacting the semiconductor layer at the opening, and extending at equal intervals in a direction perpendicular to the direction. sensor. 2) A contact image sensor according to claim 1, wherein at least the layer portion of the photoelectric conversion semiconductor layer on the side that contacts the conductive film is made of a high-resistance semiconductor film.