JPH0318057A - Image sensor - Google Patents

Abstract

PURPOSE:To enhance an yield and a density by so disposing first and second photodetector arrays at a deviated pitch of 1/2 pixel that the arrays are opposed. CONSTITUTION:A first photodetector array 10 is formed by sequentially laminating a metal electrode 12, a photoconductive layer 13 and a transparent electrode 14 on a board 11. A second photodetector array 20 is formed by sequentially laminating a transparent electrode 22, a photoconductive layer 23 and a metal electrode 24 on a transparent board 21 at the same pixel pitch as that of the array 10. The arrays 10, 20 are so arranged at a deviation pitch of 1/2 pixel that the arrays 10, 20 are opposed. Thus, image sensors formed of the arrays 10, 20 of low density formed on separate boards 11, 21 are arranged as high density image sensors. Thus, its yield is enhanced, and its density is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an image sensor that can be used in an input section of an image reading device such as a facsimile or an image scanner.
In particular, the present invention relates to a structure of a contact image sensor that can increase pixel density while improving manufacturing yield.

(Prior Art) Conventionally, an image reading device is composed of an image sensor having a plurality of photoelectric elements arranged in a line, and a plurality of IC chips for driving the image sensor. and,
A light source such as a fluorescent lamp or light-emitting diode illuminates the document surface, and the reflected light is imaged at the same size on each photoelectric element through a self-cleaning lens and stored as an electrical signal. Signals are extracted from each photoelectric element in time series to obtain both information on one line on the document surface.

Extraction of electrical signals from each photoelectric element is performed by the IC chip, which is controlled by an external control signal. Since each photoelectric element needs to be connected to the pad of the IC chip corresponding to each photoelectric element, there is a limit to the density of photoelectric elements that can be connected to the IC chip arranged on one side of the photodetector array.

Therefore, in order to increase the pixel density of the photoelectric element, an image sensor has been proposed in which IC chips are arranged on both sides of the light receiving element array.

As shown in FIG. 4, this image sensor consists of one
A film of chromium (Cr) is deposited on the substrate, and an individual electrode 2 consisting of a chromium pattern is formed by photolithographic etching.
A band-shaped photoconductive layer 3 made of a photoelectric material such as amorphous silicon (a-St) is formed thereon, and a transparent electrode 4 made of indium tin oxide (ITO) is further formed to form a plurality of photoelectric elements. They are arranged in a line. The individual electrode 2 is connected to the rectangular pixel 2a and the extraction electrode 2b,
The extraction electrodes 2b are alternately extracted in opposite directions. The end of the extraction electrode 2b is connected to a pad of an Ic chip (not shown), and the electrical signal accumulated in the photoconductive layer 3 is extracted.

(Problems to be Solved by the Invention) According to the image sensor described above, the density of photoelectric elements can be increased, but as a result, the pixels 2a of the individual electrodes 2
There was a problem in that the interval i between the two patterns narrowed, and there was a risk that adjacent chromium (Cr) patterns would short-circuit with each other during the manufacturing process, leading to a decrease in manufacturing yield.

In addition, in the structure of the image sensor described above, the distance between the pixels 2a of the individual electrodes 2 is reduced to 2 for reasons such as etching processing.
It was necessary to ensure a distance of approximately 0 μm, and it was impossible in the manufacturing process to narrow the distance between the pixels 2a any further. .

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an image sensor that can easily achieve high density and can achieve high density with a high yield.

(Means for Solving the Problems) In order to solve the problems of the conventional example described above, the present invention provides that the first light receiving element array and the second light receiving element array are shifted by 1/2 pixel pitch so that each light receiving element array It is characterized by being arranged so that they are facing each other.

The first light-receiving element array is formed by sequentially laminating a gold yttrs electrode, a photoconductive layer, and a transparent electrode on a substrate.

The second light receiving element array is formed by sequentially laminating a transparent electrode, a photoconductive layer, and a metal electrode on a transparent substrate at the same pixel pitch as the first light receiving element array.

(Function) According to the present invention, image sensors each consisting of a relatively low-density light-receiving element array formed on separate substrates are arranged to form a high-density image sensor, thereby improving yield. However, it is possible to obtain a high-density image sensor. In addition, two image sensors are installed to
h'i, the pixel spacing of a high-density image sensor can be made dense.

(Example) An example of the present invention will be described with reference to the drawings.

FIG. 1 is an explanatory plan view of an image sensor according to an embodiment, in which a first light-receiving element is shown in which a metal electrode 12 as an individual electrode, a photoconductive layer 13, and a transparent electrode 14 as a common electrode are laminated in this order on a substrate 11. The array 10 and the second photodetector array 20, which has a transparent electrode 22 as a common electrode, a photoconductor Ji2 3, and a metal electrode 24 as an individual electrode laminated in this order on a transparent substrate 21, are connected to each other between the photoelectric elements of the photodetector array. are arranged so that they face each other.

The first light receiving element array 10 will be explained with reference to FIGS. 2(a) and 2(b).

A film of chromium (C') is deposited to a thickness of 150 OA on a certain blowing plate 11 from an insulating material such as glass or ceramic, and etched by photolithography to form a pattern of rectangular amorphous elements 12a and extraction electrodes 12b. A plurality of metal electrodes 12 are formed. Amorphous silicon (a-Si) is deposited to a thickness of 2 μm so as to cover at least the pixel 12a portion of the metal electrode 12.
A strip-shaped photoconductive layer 13 is formed by depositing the photoconductive layer 13 to a film thickness of . Next, indium tin oxide (ITO) is deposited on the photoconductive layer 13 to a thickness of IOOOA to form a band-shaped transparent electrode 14, and the overlapping portion of the metal electrode 12, photoconductive layer 13, and transparent electrode 14 is The photodetector array 10 serves as a photoelectric device. Furthermore, a passivation film 15 as a protective film is deposited on the light receiving element array 10.

The second light receiving element array 20 will be explained with reference to FIGS. 3(a) and 3(b).

Indium tin oxide (ITo) is deposited to a thickness of 100 OA on a transparent substrate 2l made of an insulating material such as a glass plate, and then amorphous silicon (a-Si) is deposited to a thickness of 2 μm.
After depositing the film in a strip shape to a film thickness of
1 is exposed, and indium tin oxide (I T
A transparent electrode 2 having a plurality of notches 22c and 23c in which amorphous silicon (a-St) and amorphous silicon (a-St) are removed.
2 and a photoconductive layer 23. This notch 22c
, 23c are for removing amorphous silicon (a-St) and allowing light to pass through this portion. Therefore, the transparent electrode 22 and the photoconductive layer 23 have both pixel corresponding portions 22a and 23a formed at each pixel pitch, and connection portions 22b and 2 that connect the respective pixel corresponding portions 22a and 23a.
3b, and the interval between the pixel corresponding parts 22a and 23a is formed to be the same as the pixel pitch (1) of the first light receiving element array 10. Then, chromium (Cr) is deposited on the entire surface to a thickness of 1500A, and etched by photolithography to form rectangular pixels 24a and extraction electrodes 24b.
The metal electrode 24 is formed so that the pixel 24a is located on the pixel corresponding portions 22a and 23a. Since the pixels 24a of the metal electrode 24 are formed on the pixel corresponding parts 22a and 23a, the pixel pitch is the same as that of the first light receiving element array 10. Furthermore, the first light receiving element array 10
Similarly, a passivation film 25 as a protective film is deposited on the light receiving element array 2o.

The light receiving element arrays 1o and 20 shaped as described above are arranged so that the photoelectric elements face each other to constitute an image sensor. At this time, the second light receiving element array 2
The pixels 12a of the first light receiving element array 10 are positioned in the notches 22c and 23c of 0, and shifted by 172 pixel pitch (t/2), and the first light receiving element array 1o and the second light receiving element array 20 are Pixel 1 2 a, 2
4 Arrange a in one row. This alignment can be achieved, for example, by simultaneously forming a plurality of markers 16 on both ends of the substrate 11 by photolithography at the time of electrode creation, and forming + markers 26 at predetermined positions on both ends of the transparent substrate 21. This is done by aligning the markers 16 and 26 of the transparent substrate 2 and 11 with each other. First light receiving element array 1
0 and the second light-receiving element array 20 may be bonded and fixed using an adhesive, or may be directly fixed to the main body housing the image sensor so as to satisfy the above-mentioned conditions.

In the photodetector arrays 10 and 20 of this example, the metal electrodes were formed as individual electrodes and the transparent electrodes were formed as a common electrode, but one or both of the photodetector arrays had the opposite structure (
Of course, the common electrode may be a metal electrode and the individual electrodes may be transparent electrodes.

The image sensor configured as described above has a transparent substrate 2
The reflected light from the original is made to enter from the first side, and the reflected light is guided to the pixel 12a and the pixel 24a. The reflected light is guided to the pixel 12a via the light receiving element array 20, but the notch 22 formed in the light receiving element array 20
c, 23c, the reflected light is guided to the pixel 12a without being obstructed by the photoconductive layer 23 of the light receiving element array 20. In addition, the light receiving element array 10 and the light receiving element array 2
0, the optical path length of the imaged light differs by the thickness of the light-receiving element array 20, but since it is about 2 to 3 μm, it can be within the error range when imaged through a SELFOC lens.

According to the above embodiment, the light receiving element array 10 having pixels of 40 x 40 μm is created at 8 dots/aII, and the light receiving element array 20 having the same pixels of <40x40 μm is created at 8 dat/ops, and both are halved. If the pixel pitch (t/2-62.5μm) is shifted and joined, 16
A dot/mm image sensor can be obtained.

Further, according to the above embodiment, the metal electrode 12 of the light receiving element array 10 and the metal electrode 24 portion of the light receiving element array 20 are formed by etching on different substrates, so that the light receiving element arrays are arranged together. In this case, each pixel can be placed close to each other to the extent that they do not overlap.
The pixel spacing between the metal electrodes, which was required to be separated by about 20 μm in a t/mm image sensor, can be narrowed, and as a result, the area of both element parts can be increased, so sensitivity can be improved.

(Effects of the Invention) According to the present invention, since the image sensors are arranged from relatively low-density light receiving element arrays formed on separate substrates to form a high-density image sensor, the yield can be reduced. It is possible to obtain a high-density image sensor while improving the image quality. In addition, since it is configured with two image sensors, the pixel spacing of the high-density image sensor can be made close, and as a result, the area of the pixel portion can be increased, so the high-sensitivity image sensor can be obtained.

[Brief explanation of drawings]

FIG. 1 is an explanatory plan view showing an image sensor according to an embodiment of the present invention, FIG. FIG. 2(a) is an explanatory cross-sectional view taken along the line nn', and FIG. 3(a) is the second cross-sectional view of this embodiment.
An explanatory plan view showing the end of the light receiving element array in FIG.
) is an explanatory cross-sectional view taken along the line m-m' in FIG. 3(a), and FIG. 4 is an explanatory plan view showing a conventional image sensor. 10... Light receiving element array 11... Substrate 12... Metal electrode l3... Photoconductive layer 14... Transparent electrode 20... ... Light-receiving element array 21 ... Transparent substrate 22 ... Transparent electrode 23 ... Photoconductive layer 24 ... Metal electrode Fig. 2 (b) 3v! ! i (α) (b)

Claims (1)

[Claims] A first light receiving element array is formed by sequentially stacking a metal electrode, a photoconductive layer, and a transparent electrode on a substrate, and a first light receiving element array is formed by sequentially stacking a transparent electrode, a photoconductive layer, and a metal electrode on a transparent substrate. An image sensor comprising an element array and a second light-receiving element array formed at the same pixel pitch, shifted by 1/2 pixel pitch, and arranged so that the light-receiving element arrays face each other.