JP2573342B2 - Light receiving element - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light receiving element, and more particularly to a structure of a light receiving element suitable for use in a complete contact image sensor.

(Prior Art) Conventionally, image sensors having various structures for optically reading an information medium such as a manuscript have been proposed, for example, a contact sensor and a perfect contact sensor have been proposed. The contact-type sensor requires a rod lens array to collect the reflected light from the document and make it incident on the light-receiving unit, while the complete contact-type image sensor reads the document by bringing the document directly into contact with the light-receiving unit and running. Therefore, there is an advantage that a rod lens array is not required, so that downsizing and cost reduction can be achieved.

FIG. 3 is a cross-sectional view of a main part schematically showing the structure of a light receiving element of one unit of a conventional complete contact type image sensor.

In FIG. 1, a light receiving element 8 is provided with a first electrode 12 and a photoelectric conversion film 14 on a substrate 10 in order, and a second electrode 16 disposed on the photoelectric conversion film 14 so as to face the first electrode 12 and this electrode.
A wiring electrode electrically connected to the wiring electrode;

The photoelectric conversion film 14 is made of an amorphous silicon layer (a-Si layer)
The second electrode 16 is wire-bonded to the driver IC via the wiring electrode 18.

Then, the substrate 10 and the second electrode 16 are formed of a transparent material, and the first electrode 12 is formed of a material having a light shielding property, and the first electrode 12, the photoelectric conversion film 14, and the second electrode 16 are provided with the light guide window 20.

In such a structure, emitted light L ₁ is the substrate 1 from the light emitting element 22 disposed on the side opposite to the light receiving element 8 across the substrate 10
0, sequentially passes through the light guide window 20 reaches the original 24, and the photoelectric conversion layer is reflected light L ₂ passes through the second electrode 16 from the document 24
The light is incident on the film 14 and photoelectrically converted by the film 14.

(Problems to be Solved by the Invention) However, in the above-described conventional light receiving element, the light emitting element 22 is not used.
In order to prevent light from coming from the device 22 directly into the photoelectric conversion film 14, the first electrode 12 must be formed sufficiently wide, so that the first electrode 12, the second electrode 16 and Region R facing wiring electrode 18 (overlap region R)
Becomes wider.

However, when the photoconductive layer 14 is made of a-Si, there is no pinhole causing a short circuit between the electrode 12 and the electrodes 16 and 18.
The formation of the -Si layer is very difficult with the current technology, and as a result, the probability of occurrence of a short circuit increases as the region R is increased. The occurrence of a short circuit causes a bit defect of the image sensor, and therefore increases the probability of occurrence of a short circuit, so that the yield of the image sensor cannot be improved.

An object of the present invention is to solve the conventional problems described above,
An object of the present invention is to provide a light receiving element having a structure capable of reducing the probability of occurrence of a short circuit.

(Means for Solving the Problems) In order to achieve this object, a light-receiving element of the present invention comprises:
In a light-receiving element in which a first electrode and a photoelectric conversion film are sequentially provided on a substrate and a second electrode and a wiring electrode are provided on the photoelectric conversion film, a light-shielding layer and a light-shielding layer are sequentially provided between the substrate and the first electrode from the substrate side. An insulating layer is provided, and the end of the first electrode on the side of the wiring electrode is terminated almost immediately below a position where the end of the side of the wiring electrode connected to the second electrode is terminated, and the first electrode is wired. Pull out from the electrode to the side toward the second electrode, place the light-shielding layer immediately below the place where the end of the first electrode on the wiring electrode side is terminated, and pull out the light-shielding layer from the second electrode to the side toward the wiring electrode It is characterized by comprising.

(Operation) According to the light receiving element of the present invention, the end of the first electrode on the wiring electrode side is terminated almost immediately below the location where the end of the wiring electrode connected to the second electrode is terminated. , The first electrode,
The first electrode and the wiring electrode are pulled out from the wiring electrode to the side toward the second electrode. Therefore, the first electrode and the wiring electrode hardly overlap each other in a plan view, so that the first electrode and the wiring electrode are electrically connected via the pinhole of the photoelectric conversion film. Can be reduced.

In addition, the light-shielding layer is arranged immediately below the location where the end of the first electrode on the wiring electrode side is terminated, and the light-shielding layer is drawn out from the second electrode toward the wiring electrode. The first electrode and the wiring electrode can prevent the light from directly entering the photoelectric conversion film without being reflected by the original.

(Example) Hereinafter, an example of the present invention will be described. It should be noted that the drawings are only schematically shown to the extent that these inventions can be understood, and therefore the shapes, dimensions, and arrangement positions of the components are not limited to the illustrated examples. In this embodiment, an example in which the present invention is applied to an image sensor will be described.

1 (A) and 1 (B) are diagrams schematically showing the configuration of an embodiment of the present invention, and FIG. 1 (A) is a diagram showing I in FIG. 1 (B).
Sectional drawing showing the structure of one unit of light receiving element taken along line A-IA, and FIG. 2B is a plan view showing the structure of the light receiving element in the image sensor when viewed two-dimensionally, which is cut out stepwise. It is.

As shown in FIG. 1, the light receiving element 30 of this embodiment has a structure in which a first electrode 32 and a photoelectric conversion film 34 are sequentially provided on a substrate 36, and a second electrode 38 and a wiring electrode 40 are provided on the photoelectric conversion film 34. And a light shielding layer between the substrate 36 and the first electrode 32 sequentially from the substrate 36 side.
It has a structure in which 42 and an insulating layer 44 are provided. And wiring electrodes
The end of the first electrode 32 on the side of the wiring electrode 40 is terminated almost immediately below the location where the end of the side 40 connected to the second electrode 38 is terminated, and the first electrode 32 is connected to the wiring electrode 40. To the side toward the second electrode 38. Further, a light-shielding layer 42 is disposed immediately below a position where the end of the first electrode 32 on the side of the wiring electrode 40 is terminated, and the light-shielding layer 42 is drawn out from the second electrode 38 toward the wiring electrode 40.

 Hereinafter, this embodiment will be described in more detail.

In this embodiment, the substrate 36 and the second electrode 38 are a substrate and an electrode made of a transparent material, the first electrode 32 is an electrode made of a light shielding material, and the first electrode 32, the photoelectric conversion film 34 and the second electrode 38 Are provided with light guide windows 46a, 46b, 46c, respectively. Further, the first electrode 32 and the second electrode 38 are arranged to face each other, and the wiring electrode
40 is electrically connected to the second electrode 38.

The light receiving element 30 of this embodiment constitutes a complete contact image sensor having a structure in which a plurality of the elements 30 are arranged in parallel in a row, and the first electrode 32 and the photoelectric conversion film 34 are formed by a light receiving element.
A band-shaped electrode and film extending in the arrangement direction of 30 and are used as a common electrode and film for each light receiving element 30, and a second electrode 38 and a wiring electrode 40 are separately provided for each light receiving element 30 Electrodes. This image sensor has a light source, for example, a light-emitting diode
With a diode array consisting of 48 arranged in an array,
A structure in which light from the light emitting diode 48 is irradiated to an information medium (not shown) through the light guide windows 46a, 46b, and 46c, and light reflected by the information medium is transmitted through the second electrode 38 and made incident on the photoelectric conversion film 34. Having.

In order to prevent the light L from the light emitting diode 48 from directly entering the photoelectric conversion film 34 from the diode 48, the light L is blocked by the light shielding layer 42 and the first electrode 32. The overlapping portion 50 of the layer 42 and the electrode 32 is arranged so that the light L does not directly enter the photoelectric conversion film 34 via the gap p (see FIG. 1A) between the electrode 32 and the light shielding layer 42. Formed.

Almost immediately below the place where the end of the wiring electrode 40 connected to the second electrode 38 is terminated, the end of the first electrode 32 on the wiring electrode 40 side is terminated, and the first electrode 32 is wired. Since the first electrode 32 and the wiring electrode 40 are pulled out from the electrode 40 toward the second electrode 38, they do not overlap with each other except for a very small overlap outside the pixel region 52 in a plan view. Moreover, even if the first electrode 32 is provided in this manner, the first electrode 32
A light-shielding layer immediately below the location where the end on the side of the wiring electrode 40 is terminated
42, and the light-shielding layer 42 is drawn from the second electrode 38 toward the wiring electrode 40, so that the light-emitting diode
When the light L from 48 is directly incident on the photoelectric conversion film 34,
This can be prevented by the first electrode 32 and the light shielding layer 42.

Since the first electrode 32 and the wiring electrode 40 can hardly overlap each other when viewed in plan, the first electrode 32 and the wiring electrode 40 are electrically connected to each other through the pinhole of the photoelectric conversion film 34. The probability of contact (in other words, the occurrence of a short circuit) can be reduced, thereby reducing bit defects and improving the yield of the image sensor as compared with the related art. For example, according to this embodiment, the yield can be improved to about 60%, while the yield is about 10% in the conventional structure.

In order to reduce the probability of occurrence of a short circuit, a portion of the first electrode 32 on the wiring electrode 40 side when viewed in a plan view is a pixel region 52 (for example, a region indicated by hatching in FIG. 1B). Preferably, the probability of occurrence of a short circuit can be effectively reduced.

 Next, the manufacturing method of this embodiment will be described.

2 (A) to 2 (F) are cross-sectional views showing the manufacturing steps of this embodiment step by step, and show cross sections corresponding to FIG. 1 (A).

First, a transparent insulator substrate made of, for example, glass is prepared as the substrate 36, and a layer made of a light-shielding material is deposited on one substrate surface of the substrate 36, and then this layer is patterned to obtain a structure shown in FIG. The light shielding layer 42 is formed as shown in FIG. For example, chromium (Cr) or nichrome (NiCr) is used as a light-shielding material, and this light-shielding material is deposited on a substrate surface by a vacuum evaporation method or a sputtering method so as to have a layer thickness of about 1000 to 2000 mm. .

Next, as shown in FIG. 2 (B), an insulating layer 44 is deposited on the light shielding layer 42 for insulation between the first electrode 32 and the light shielding layer 42. For example, the SiO _x layer or SiN _x layer as an insulating layer 44
It is formed with a layer thickness of about 500 to 1 μm.

Preferably, the layer thickness of the insulating layer 44 is sufficiently larger than the layer thickness of the light shielding layer 42 so that the surface 42a of the insulating layer 44 is substantially flat.

After the formation of the insulating layer 44, an electrode material is deposited to form a first electrode layer, and then the first electrode is patterned to provide a light guide window 46a as shown in FIG. 2 (C). One electrode 32 is formed. For example, chromium or nichrome is used as the electrode material.

In forming the first electrode 32, an overlapping portion 50 is formed so as to prevent light L from the light emitting diode 48 from directly entering the photoelectric conversion film 34, and the first electrode 32 is viewed in plan. The first electrode 32 is formed such that the portion on the side of the wiring electrode 40 is disposed in the pixel region 52.

For example, when the thickness of the insulating layer 44 is about 500 ° to 1 μm, the width t of the overlapping portion 50 in the direction along the substrate surface is about 1 μm to 1 mm, so that the light L to the photoelectric conversion film 34 is reduced. Direct incidence can be blocked.

After the formation of the first electrode 32, amorphous silicon (hereinafter a-Si) is formed on the first electrode 32 as shown in FIG.
Is selectively deposited to form a photoelectric conversion film 34 of a semiconductor layer made of a-Si. For example, a film thickness of 0.5 to 1.5 by a glow discharge method using a source gas containing SiH ₄ as a main component.
A photoelectric conversion film 34 is formed by depositing a-Si of about μm. A-Si can be selectively deposited by using a mask.

Next, an electrode material is deposited on the photoelectric conversion film 34 to form a second electrode layer, and then the second electrode layer is patterned to form a second electrode layer.
As shown in FIG. 5E, the second electrode 38 having the light guide window 46c is provided.
To form A transparent conductive material, for example, ITO (Indium Tin Oxide) is used as an electrode material of the second electrode 38.

Next, an electrode material is deposited on the second electrode 38 to form a third electrode layer, and then the third electrode layer is patterned to form a wiring electrode.
The light-receiving element 30 is formed, and then the photoelectric conversion film 34 is patterned to form the light-guiding window 46b, thereby obtaining the light-receiving element 30 having a structure as shown in FIG. 2 (F).

As the electrode material of the wiring electrode 40, for example, a metal (metal) material such as aluminum is used.

The present invention is not limited only to the above-described embodiments, and accordingly, the arrangement positions, forming materials, shapes, and configurations of the respective components can be suitably changed. For example, in the above-described embodiment, an example in which the image sensor is configured by arranging the light receiving elements in a row has been described. However, the arrangement position of the light receiving element may be arbitrarily changed in order to configure the image sensor. For example, an image sensor may be configured by arranging light receiving elements two-dimensionally. The light receiving element may be used not only for the image sensor but also for forming various optical elements. Therefore, the shapes, arrangement positions, and forming materials of the electrodes, the photoelectric conversion film, the light shielding layer, and other components may be appropriately determined. Can be changed. For example, the pixel area may be an area for one pixel set to any suitable shape and size, and thus the size and shape of the pixel area are not limited to those in the illustrated example.

In the above-described embodiments, specific materials, forming methods, manufacturing process orders, and specific numerical conditions have been described in order to deepen the understanding of the present invention. However, these materials, forming methods, manufacturing process orders, and conditions are examples. Therefore, it can be changed in any suitable manner within the scope of the present invention.

(Effects of the Invention) As is apparent from the above description, according to the light receiving element of the present invention, the first electrode is provided almost immediately below the place where the end of the wiring electrode connected to the second electrode is terminated. And the first electrode is pulled out from the wiring electrode toward the second electrode, so that the first electrode and the wiring electrode are outside the pixel region when viewed in plan. Except that they overlap only slightly. Moreover, even when the first electrode is provided in this manner, the light-shielding layer is disposed immediately below the location where the end on the wiring electrode side of the first electrode is terminated, and the light-shielding layer is moved from the second electrode to the wiring electrode. The first electrode and the light shielding layer can prevent light from the light emitting element disposed on the back side of the substrate from directly entering the photoelectric conversion film without being reflected by the document.

By providing the first electrode in this manner, the first electrode and the wiring electrode can be prevented from almost overlapping each other when viewed in a plan view. The probability of electrical contact through the hole can be reduced.

Therefore, if the present invention is applied to the manufacture of a light receiving element of an image sensor, the occurrence of bit defects can be stochastically reduced and the yield of the image sensor can be improved.

[Brief description of the drawings]

1 (A) and 1 (B) are a cross-sectional view and a plan view schematically showing a configuration of an embodiment of the present invention, and FIGS. 2 (A) to 2 (F) are explanations of a manufacturing process of the embodiment of the present invention. FIG. 3 is a sectional view schematically showing the structure of a conventional light receiving element. 30 ... light receiving element, 32 ... first electrode 34 ... photoelectric conversion film, 36 ... substrate 38 ... second electrode, 40 ... wiring electrode 42 ... light shielding layer, 44 ... insulating layer 50 ... overlap Part, 52 ... Pixel area.

Claims (1)

(57) [Claims] 1. A light receiving element comprising a first electrode and a photoelectric conversion film sequentially provided on a substrate, and a second electrode and a wiring electrode provided on the photoelectric conversion film, wherein a substrate is provided between the substrate and the first electrode. A light-shielding layer and an insulating layer are sequentially provided from the side, and the end of the first electrode on the wiring electrode side is terminated almost immediately below the place where the end of the wiring electrode connected to the second electrode is terminated. Pulling out the first electrode from the wiring electrode toward the second electrode, disposing a light-shielding layer immediately below a location where an end of the first electrode on the wiring electrode side is terminated, A light-receiving element, which is drawn out from two electrodes toward a wiring electrode.