JPH0645634A - Photoelectric conversion element and its manufacture - Google Patents

Abstract

PURPOSE:To provide a photoelectric conversion element wherein the element is favorable for a fine shape and an irregularity in the area of a photodetection part is small and to provide its manufacturing method. CONSTITUTION:A lower metal electrode 12, a photoelectric conversion layer 13, an upper transparent conductive film 14 and an upper metal electrode 15 are laminated and formed sequentially, and the outer circumferential shape of the photo-electric conversion layer 13, the upper transparent conductive film 14 and the upper metal electrode 15 is formed to be nearly identical within a prescribed dimensional error. Since the outer circumferential shape of the photo-electric conversion layer 13, the upper transparent conductive film 14 and the upper metal electrode 15 is formed to be nearly identical within the prescribed dimensional error, it is very favorable for making an element fine and an irregularity in the characteristic or the like of the element can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photoelectric conversion element used for image reading of facsimiles, copying machines and the like and a method for manufacturing the same.

[0002]

2. Description of the Related Art Generally, solid-state image pickup devices, linear sensors,
A photoelectric conversion element is used for the area sensor and the like.
9A and 9B are a plan view and a sectional view of a conventional photoelectric conversion element. Referring to FIGS. 9A and 9B, a conventional photoelectric conversion element includes a lower metal electrode 2 such as Cr and a photoelectric conversion layer 3 such as amorphous silicon (a-Si) on an insulating substrate 1 such as glass. , Upper transparent conductive film 4 such as ITO, Cr,
An upper metal electrode 5 made of Al or the like is sequentially laminated and formed. Here, the photoelectric conversion layer 3 is doped with P-type impurities on its upper portion, that is, on the contact portion with the upper transparent conductive film 4. There is also a structure in which the photoelectric conversion layer 3 has a PIN structure in which a lower part, that is, a contact portion with the lower metal electrode 2 is doped with N-type impurities. In a linear sensor or the like, the photoelectric conversion elements are arranged as a one-dimensional or two-dimensional array. In this case, the photoelectric conversion element corresponds to one pixel, and the photoelectric conversion layer 3
Are separated for each pixel.

FIGS. 10A to 10E are shown in FIGS.
It is a figure which shows the example of a concrete manufacturing process of the photoelectric conversion element of (b). In order to manufacture the photoelectric conversion element shown in FIGS. 9A and 9B, about 1000 Å of Cr to be the lower metal electrode 2 is deposited on the glass insulating substrate 1 by sputtering, and the photoelectric conversion layer 3 is formed. Amorphous silicon (a-S
i) is deposited by plasma CVD to about 8000 Å, and ITO to be the upper transparent conductive film 4 is deposited by sputtering to about 7
About 100Å is deposited by sputtering, and Cr to be the upper metal electrode 5 is deposited about 500Å by sputtering (FIG. 10A). Subsequently, Cr, which will be the upper metal electrode 5, is patterned into a predetermined shape by a normal photoengraving process (FIG. 10B).
Further, the ITO serving as the upper transparent conductive film 4 is patterned into a predetermined shape (FIG. 10C), and the a-Si serving as the photoelectric conversion layer 3 is patterned into a predetermined shape (FIG. 10C).
(D)) After that, Cr which becomes the lower metal electrode 2 is patterned into a predetermined shape (FIG. 10).
(E)), and the photoelectric conversion element of FIGS. 9 (a) and 9 (b) can be formed.

In the photoelectric conversion element having such a structure, a reverse bias is applied to the photoelectric conversion layer 3 by the lower metal electrode 2 and the upper metal electrode 5. In this state, when light is incident through the upper transparent conductive film 4, carriers are generated in the photoelectric conversion layer 3 in an amount corresponding to the amount of light, and photoelectric conversion can be performed by extracting the carriers as photocurrent. .

[0005]

However, in the above-mentioned conventional photoelectric conversion element, each of the constituent parts thereof, that is, the lower metal electrode 2, the photoelectric conversion layer 3, the upper transparent conductive film 4, and the upper metal electrode 5 are respectively formed. Since they are formed with individual dimensions and shapes, there is a problem that it is difficult to miniaturize the element because it is necessary to design the element with a margin for each part. Also, since each of the above parts are individually manufactured,
There is a problem that the manufacturing process is complicated and it is difficult to manufacture the device with high accuracy. For example, in FIG.
In the configuration of (b), the area of the light receiving portion is determined by the shape of the photoelectric conversion layer 3, the shape of the upper transparent conductive film 4 and the upper metal electrode 5, and the matching precision between them, so that the light receiving portion is formed with high accuracy. However, the area of the light receiving portion varies from pixel to pixel.

It is an object of the present invention to provide a photoelectric conversion element which is advantageous for miniaturization and has less variation in the area of the light receiving portion, and a method for manufacturing the photoelectric conversion element.

[0007]

In order to achieve the above object, the invention according to claims 1 and 2 is such that a lower metal electrode, a photoelectric conversion layer, an upper transparent conductive film, and an upper metal electrode are sequentially laminated. In the photoelectric conversion element thus formed, the photoelectric conversion layer, the upper transparent conductive film, and the upper metal electrode are formed to have substantially the same outer peripheral shape within a predetermined dimensional error. Since the outer peripheral shapes of the photoelectric conversion layer, the upper transparent conductive film, and the upper metal electrode are formed to be almost the same within a predetermined dimensional error, it is very advantageous for miniaturization of the element, and the characteristics of the element, etc. Variation can be reduced.

Further, the invention according to claim 3 is further characterized in that at least a part of the shape of the light receiving portion is formed by patterning the upper metal electrode. Since at least a part of the shape of the light receiving portion is formed only by patterning the upper metal electrode, the area of the light receiving portion can be reduced in the case where the photoelectric conversion elements are arranged in a line or a matrix. It is possible to reduce the variation for each pixel.

According to a fourth aspect of the invention, there is provided a step of forming the outer peripheral shapes of the photoelectric conversion layer, the upper transparent conductive film and the upper metal electrode by the same photolithography, and at least a part of the shape of the light receiving portion is the upper metal electrode. And a step of forming by photolithography. As a result, the number of steps can be reduced as compared with the related art, and it is possible to obtain a photoelectric conversion element that is advantageous in miniaturization and has less variation in the area of the light receiving section, with simple steps.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. 1 (a) and 1 (b) are a plan view and a sectional view of an embodiment of a photoelectric conversion element according to the present invention. Figure 1 (a),
The photoelectric conversion element of (b) includes a lower metal electrode 12 such as Cr, a photoelectric conversion layer 13 such as amorphous silicon (a-Si), an upper transparent conductive film 14 such as ITO, and Cr on an insulating substrate 11 such as glass. , Al and other upper metal electrodes 15 are sequentially laminated and formed. By patterning the upper metal electrode 15, the light receiving window 16 having a predetermined size and shape is formed. That is, as shown in FIG.
In the configuration of (b), the shape of the light receiving portion is obtained by patterning the upper metal electrode 15.

The thickness of the upper transparent conductive film 14 is usually 1
The thickness of the photoelectric conversion layer 13 is usually 1 μm or less.
m or less, and the pattern of the upper transparent conductive film 14 (outer peripheral shape) and the pattern of at least part of the upper metal electrode 15 (that is, outer peripheral shape) are within twice the film thickness of the upper transparent conductive film 14. There is an error, and the photoelectric conversion layer 13
The pattern (outer peripheral shape) and the pattern (outer peripheral shape) of the upper transparent conductive film 14 are matched with each other with a dimensional error within twice the film thickness of the photoelectric conversion layer 13.

In the photoelectric conversion element having such a configuration, all the patterns (outer peripheral shape) of the photoelectric conversion layer 13, all the patterns (outer peripheral shape) of the upper transparent conductive film 14, and at least a part of the upper metal electrode 15. Pattern (peripheral shape)
It is formed by the first photolithography, and the pattern of the upper metal electrode 15 which becomes at least a part of the shape of the light receiving portion is formed by the second photolithography. That is, in the present invention, the photoelectric conversion layer 13, the upper transparent conductive film 1
4, a step (first photoengraving step) of producing the periphery of each of the upper metal electrodes 15, that is, the outer periphery by the same photoengraving (first photoengraving), and an upper metal electrode 15 formed by the second photoengraving The photoelectric conversion element is manufactured by two photomechanical processes including the process of forming the light receiving window 16 and forming the pattern (outer peripheral shape) of the lower metal electrode 12 (second photomechanical process). .

In the photoelectric conversion element having such a structure, the photoelectric conversion layer 13, the upper transparent conductive film 14, the upper metal electrode 15 are formed.
Since each periphery is formed by patterning in the same photolithography process, it is not necessary to consider the alignment margin for each of these portions, and the photolithography process can be accurately performed with fewer photolithography processes than in the past. At least a part of the pattern of the upper transparent conductive film 14 and the pattern of the upper metal electrode 15 are matched with each other with a dimensional error within twice the film thickness of the upper transparent conductive film 14, and the pattern of the photoelectric conversion layer 13 and the upper transparent conductive film 14 are matched. It is necessary to match all of the patterns with the dimensional error within twice the film thickness of the photoelectric conversion layer,
Since the film thickness of the upper transparent conductive film 14 is usually 1000 Å or less and the film thickness of the photoelectric conversion layer 13 is usually 1 μm or less, it is not possible to realize the conventional method because the alignment margin must be taken into consideration. According to the present invention, it can be easily realized by patterning in the same photolithography process.

Further, in the present invention, since the light receiving window 16, that is, the light receiving portion is determined only by patterning the upper metal electrode 15, it is possible to realize a photoelectric conversion element having a small variation in the light receiving portion area.

The basic operation of the photoelectric conversion element is the same as that of the conventional one shown in FIG. 1, except that the potential on the upper transparent conductive film 14 side is output or reset. Since the periphery of the upper transparent conductive film is surrounded by the upper metal electrode 15 having a lower resistance, it is advantageous for high-speed reset.

2 (a) to 2 (c) are shown in FIG. 1 (a),
It is a figure which shows the manufacturing process example of the photoelectric conversion element of (b). In this manufacturing example, first, Cr, which will become the lower metal electrode 12, is sputtered on the glass insulating substrate 11 to about 100.
Amorphous silicon (a-Si) which is to be the photoelectric conversion layer 13 is deposited to a thickness of 0 Å by plasma CVD to about 80
IT which is deposited as 00Å and becomes the upper transparent conductive film 14 thereon
About 700 Å of O is deposited by sputtering, and about 500 Å of Cr to be the upper metal electrode 15 is further deposited thereon by sputtering (FIG. 2 (a)). Here, the a-Si to be the photoelectric conversion layer 13 has a layer of about 500 Å doped with boron as a P-type impurity on the upper part thereof.

Then, Cr, which becomes the upper metal electrode 15,
The ITO serving as the upper transparent conductive film 14 and the amorphous silicon (a-Si) serving as the photoelectric conversion layer 13 are patterned into a predetermined shape by a single photolithography process (FIG. 2).
(B)).

Further, Cr which becomes the lower metal electrode 12,
The light receiving window 16 inside Cr which becomes the upper metal electrode 15 is patterned into a predetermined shape by a single photolithography process (FIG. 2C). As a result, the photoelectric conversion element shown in FIGS. 1A and 1B can be formed.

The photoelectric conversion element shown in FIGS. 1A and 1B is usually connected to another driving element by an external extraction electrode such as Al. FIG. 3 is a diagram (cross-sectional view) showing a configuration example in which the photoelectric conversion element of FIGS. 1A and 1B is further provided with an external extraction electrode. In the example of FIG. 3, an insulating film 17 is formed on the photoelectric conversion elements of FIGS. 1A and 1B, a contact hole is formed in the insulating film 17, and then the external extraction electrode 1 such as Al is formed.
8 is deposited by sputtering or the like, and is further patterned by a photoengraving process. This external extraction electrode 18 is used to connect to other elements.

4 (a), (b), FIG. 5 (a),
6B, FIG. 6A, and FIG. 6B are a plan view and a cross-sectional view, respectively, of another embodiment of the photoelectric conversion element according to the present invention. Figure 1
In the photoelectric conversion elements shown in (a) and (b), all four sides of the light receiving window 16 are defined by the upper metal electrode 15. In this case, the light receiving window 16 is defined by the upper metal electrode 1.
Although it is formed inside 5, in the example of FIGS. 4A and 4B, among the four sides R1 to R4 around the light receiving window 16, only three sides R1, R2 and R3 are formed by the upper metal electrode 15. It has been prescribed. In the example of FIGS. 5A and 5B, only the two sides R2 and R4 of the four sides R1 to R4 around the light receiving window 16 are defined by the upper metal electrode 15. Further, in the example of FIGS. 6A and 6B,
Of the four sides R1 to R4 around the light receiving window 16, only one side R2 is defined by the upper metal electrode 15. That is, FIG. 4 (a), (b), FIG. 5 (a),
In the example of (b), FIG. 6 (a), and (b), the light receiving window 16 is
Although it is also formed on the outer side of the upper metal electrode 15, even in this case, the light receiving window 16 is formed by one photoengraving process, and therefore, similar to the case of FIGS. 1A and 1B. To
The variation in area can be reduced as compared with the conventional case.

FIG. 7 is a diagram showing a structural example of a one-dimensional array using the photoelectric conversion elements shown in FIGS. 1 (a), 1 (b) or 3. The one-dimensional array of FIG. 7 is configured by arranging a plurality of the photoelectric conversion elements of FIGS. 1A, 1B or 3 in a one-dimensional array C1 to Cn. In this case, the lower metal electrode 12 made of Cr of each photoelectric conversion element C1 to Cn
Is connected to the individual electrode 22 for each photoelectric conversion element through the contact hole 20, and the upper metal electrode 15
Are connected to the common electrode 21 through the contact holes 19.

FIG. 8 is a diagram showing an example of the structure of a one-dimensional array using the photoelectric conversion elements of FIGS. 5 (a) and 5 (b).
The one-dimensional array shown in FIG. 8 is configured by arranging a plurality of photoelectric conversion elements shown in FIGS. 5A and 5B in a one-dimensional array form. In this case, the lower metal electrode 12 made of Cr of each of the photoelectric conversion elements C1 to Cn serves as a common electrode, and the upper metal electrode 15 serves as the contact hole 19
It is connected to the individual electrode 22 via the and has a very simple layout.

The inventor of the present application actually manufactured the photoelectric conversion element by the manufacturing process shown in FIGS. 2 (a) to 2 (c). As a result, a photoelectric conversion element having a pattern minimum dimension of 5 μm could be obtained. In addition, in manufacturing the conventional photoelectric conversion element shown in FIGS. 9A and 9B, it is necessary to consider an alignment margin of about 2 μm as a whole, whereas in FIGS. In manufacturing the photoelectric conversion element of b), it was possible to eliminate the need to consider the alignment margin. Further, conventionally, four photoengraving steps were required as shown in FIGS. 10A to 10E, but in the present invention, two photoengraving steps were performed as shown in FIGS. 2A to 2C. The photoelectric conversion element could be formed only by the photoengraving process, and the manufacturing process could be simplified. In both of the two patterning processes, the positive type OFPR- was used as the photoresist.
800 (manufactured by Tokyo Ohka) was used. Further, Cr is patterned using a cerium nitrate-based etching solution, and ITO is patterned using a hydrochloric acid-based etching solution, and amorphous silicon (a-Si) is CF4.
Patterning was performed by dry etching using a system gas. Furthermore, when a one-dimensional array having a structure of about 25 mm in length as shown in FIG. 7 was created and the variation in the area of the light receiving part for each pixel was evaluated, it was about 10% in the past. In the case of the invention, the variation in the area of the light receiving part is about 5%.
However, the accuracy of the area of the light receiving portion could be improved.

[0024]

As described above, according to the first and second aspects of the invention, the outer peripheral shapes of the photoelectric conversion layer, the upper transparent conductive film and the upper metal electrode are substantially the same within a predetermined dimensional error. Since it is formed, it is very advantageous for miniaturization of the element and it is possible to reduce variations in the characteristics of the element.

Further, according to the invention of claim 3, since at least a part of the shape of the light receiving portion is formed by patterning the upper metal electrode, the photoelectric conversion element is formed in, for example, a line shape or a matrix shape. It is possible to reduce the variation in the area of the light receiving unit for each pixel in the case of configuring the array arranged in.

According to a fourth aspect of the invention, the step of forming the outer peripheral shapes of the photoelectric conversion layer, the upper transparent conductive film and the upper metal electrode by the same photolithography, and at least part of the shape of the light receiving portion Since it has a step of forming on the metal electrode by photolithography, the number of steps can be reduced as compared with the conventional one, it is a simple step, advantageous for miniaturization, and there is little variation in the area of the light receiving part. A photoelectric conversion element can be obtained.

[Brief description of drawings]

1A and 1B are a plan view and a cross-sectional view of an embodiment of a photoelectric conversion element according to the present invention.

2A to 2C are diagrams showing an example of a manufacturing process of the photoelectric conversion element of FIGS. 1A and 1B.

FIG. 3 is a diagram showing a configuration example in which an external extraction electrode is further provided to the photoelectric conversion element of FIGS. 1 (a) and 1 (b).

4 (a) and 4 (b) are a plan view and a sectional view of another embodiment of the photoelectric conversion element according to the present invention.

5 (a) and 5 (b) are a plan view and a sectional view of another embodiment of the photoelectric conversion element according to the present invention.

6 (a) and 6 (b) are a plan view and a sectional view of another embodiment of the photoelectric conversion element according to the present invention.

FIG. 7 is a diagram showing a configuration example of a one-dimensional array using the photoelectric conversion element of FIG. 1 (a), (b) or FIG.

FIG. 8 is a diagram showing a configuration example of a one-dimensional array using the photoelectric conversion elements of FIGS. 5 (a) and 5 (b).

9A and 9B are a plan view and a sectional view of a conventional photoelectric conversion element.

10A to 10E are diagrams showing an example of a manufacturing process of the photoelectric conversion element of FIGS. 9A and 9B.

[Explanation of symbols]

 11 Insulating substrate 12 Lower metal electrode 13 Photoelectric conversion layer 14 Upper transparent conductive film 15 Upper metal electrode 16 Light receiving window

Claims (4)

[Claims] 1. A photoelectric conversion device comprising a lower metal electrode, a photoelectric conversion layer, an upper transparent conductive film, and an upper metal electrode, which are sequentially stacked, and a peripheral shape of the photoelectric conversion layer, the upper transparent conductive film, and the upper metal electrode. Are formed to be substantially the same within a predetermined dimensional error. 2. The photoelectric conversion element according to claim 1, wherein
The outer peripheral shape of the upper transparent conductive film and the outer peripheral shape of the upper metal electrode coincide with each other with a dimensional error within twice the film thickness of the upper transparent conductive film, and the outer peripheral shape of the photoelectric conversion layer and the outer peripheral conductive film are A photoelectric conversion element having a dimensional error within twice the film thickness of the photoelectric conversion layer. 3. The photoelectric conversion device according to claim 1,
Further, the photoelectric conversion element is characterized in that at least a part of the shape of the light receiving portion is formed by patterning the upper metal electrode. 4. A step of forming the outer peripheral shapes of the photoelectric conversion layer, the upper transparent conductive film, and the upper metal electrode by the same photolithography, and a step of forming at least a part of the shape of the light receiving portion on the upper metal electrode by the photolithography. A method for manufacturing a photoelectric conversion element, comprising: