JPH03230569A - Image sensor and manufacture thereof - Google Patents

Abstract

PURPOSE:To prevent a short circuit between a common electrode and a wire for an individual electrode by providing a wire for the individual electrode on a photoelectric conversion film via an insulating layer comprising either or both of amorphous carbon and hydrocarbon polymer. CONSTITUTION:Numerous light receiving parts 19 having a common electrode 13, a photoelectric conversion film 15 and an individual electrode 17 in this order are provided on a substrate 11, and a wire 21 for the individual electrode connected to the individual electrode is additionally provided. Further an insulating layer 31 comprising either or both of amorphous carbon hydride (a-C:H) for example as amorphous carbon (a-C) and hydrocarbon polymer is provided between the photoelectric conversion film 15 and the wire 21 for the individual electrode. Thus even if a pin hole exists on a region of the photoelectric conversion film where the wire for the individual electrode faces the common electrode, a function of the insulating layer 31 can prevent a short circuit between the common electrode and the wire for the individual wire so as to reduce a rate of occurrence of bit defects.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an image sensor and a manufacturing method thereof.

(Prior art) In recent years, image information processing devices, such as those seen in facsimile machines, have become indispensable in the "information-oriented society."In order to construct such devices, high-performance image sensors are required. Therefore, image sensors with various structures have been proposed in the past.

Among various image sensors, a complete double-layer image sensor can read a document by directing the document to the light-receiving section, which eliminates the need for a reduction optical system or rod lens array, allowing for the miniaturization of image information reading devices. It was something.

Hereinafter, the structure of a conventional image sensor will be briefly explained using an example of a completely room-mounted image sensor. Figure 3 (A)
and (B) are diagrams for explaining the same, and are a cross-sectional view and a plan view schematically showing the structure of a conventional full coverage image sensor (hereinafter sometimes abbreviated as an image sensor). . The cross-sectional view shown in FIG. 3(A) is similar to that shown in FIG.
This corresponds to the I-I line sectional view in 8). Note that in both figures, it should be understood that there are components that are illustrated in one drawing but not illustrated in the other drawing.

This image sensor includes a large number of light receiving sections 19 having a common electrode 13, a photoelectric conversion film 15, and individual electrodes 17 in this order on a glass substrate 11, and further includes individual electrode wiring 21 connected to the individual electrodes 17. It consisted of ingredients.

Here, the common electrode 13 is made of a metal film having a light-shielding property such as chromium, the photoelectric conversion film 15 is made of hydrogenated amorphous silicon (a-3i:H), and the individual electrodes 17 are made of ITOW. It is composed of transparent conductive films such as
The individual electrode wiring 21 was made of, for example, aluminum. Each light receiving section 19 is provided with a light guide window 23 formed by removing a portion of each of the individual electrodes 17, the photoelectric conversion film 15, and the common electrode 13. The common electrode 13 is an LED
It also functioned as a light-shielding film that prevents light emitted from the array 27 from directly entering the photoelectric conversion film 15. The individual electrode wiring 21 was connected to the driver C through a wire, for example, in an area not shown.

When using this image sensor, the original 25 is pressed against the image sensor on the individual electrode 17 side.

The LED array 27 serving as a light source is placed opposite the image sensor on the glass substrate 11 side.

According to this configuration, the light emitted from the LED array 27 passes through the light guiding window 23 and hits the original 25, and then is reflected by the original 25 and enters the photoelectric conversion film 15. As a result, the shading information of the document 25 is detected by the image sensor.

(Problems to be Solved by the Invention) However, in the image sensor having the above-described configuration, the individual electrode wiring 21 or the photoelectric conversion film 15 is directly provided. Further, since the sensor structure is completely coated, the common electrode 13 has a relatively large area so as to function as a light shielding layer. For this reason, the common electrode 13 and the individual electrode wiring 21 have a structure in which they face each other over a wide area with the photoelectric conversion film 15 in between (see part P in FIG. If such a common electrode 13 and the individual electrode wiring 21 are present, an inter-electrode short circuit is very likely to occur, resulting in a problem in that bit defects are likely to occur.

Of course, in the image sensor having the configuration shown in FIG. 3, is there a possibility that an inter-electrode short circuit due to the pinhole may occur between the common electrode 13 and the individual electrodes 17?
Considering the size of the area where the electrodes face each other, the main cause that tends to cause bit defects is considered to be an inter-electrode short between the common electrode 13 and the individual electrode wiring 21.

This invention was made in view of the above points, and therefore, an object of the present invention is to eliminate short-circuits at the electrode gates caused by pinholes even when pinholes exist in the photoelectric conversion film. An object of the present invention is to provide an image sensor having a structure that is difficult to maintain, and a method for easily manufacturing the same.

(Means for Solving the Problem) In order to achieve this object, according to the first invention of this application, a large number of light receiving elements each having a common electrode, a photoelectric conversion film, and an individual electrode in this order are provided on a substrate. In an image sensor further comprising individual 81J electrode wires connected to the individual electrodes, one or both of amorphous carbon (a-C) and hydrocarbon polymer is used between the charge conversion membrane and the individual electrode wires. It is characterized by comprising an insulating layer consisting of:

Further, according to the second invention of this application, a large number of light receiving elements each having a common electrode, a photoelectric conversion film, and an individual electrode in this order are provided on a substrate, and further, individual electrode wiring connected to the individual electrode, For each image sensor manufactured, the image sensor includes the photoelectric conversion film described above and an insulating layer made of one or both of amorphous carbon and a hydrocarbon polymer provided between the wirings for the individual electrodes. The formation of the insulating layer is carried out in the following (A) and (
It is characterized in that it is carried out according to the procedure of B).

(A) Regarding the individual electrodes, a transparent conductive film is deposited on the photoelectric conversion film, a mask is formed on the transparent conductive crotch to cover the area of the transparent conductive film that is to be the individual electrode, and then the mask is formed. A sample was placed in a plasma generator, and the above-mentioned transparent conductive film was formed by mid-dry etching using a mixed gas of hydrogen and a hydrocarbon represented by C1H□ without heating the sample. Formed by etching (however, in the above - bottom of the ship, n is an integer of 1 or more, m is 4≦
An integer that satisfies m≦20+2. ).

(8) Regarding the insulating layer, one of amorphous carbon and a hydrocarbon polymer or A thin film consisting of both is deposited, and a corresponding image sample is taken out from the plasma generator described above and the thin film described above is patterned.

Here, specific examples of the hydrocarbon represented by the above-mentioned bottom include methane, ethane, propane, butane, ethylene, propylene, acetylene, and the like.

Further, in carrying out the second invention, it is preferable that the heating temperature of the above-mentioned sample be 50 to 200°C.

(Function) According to the configuration of the first invention described above, the individual electrode wiring is provided on the photoelectric conversion film via an insulating layer made of one or both of amorphous carbon and a hydrocarbon polymer.

It is rare for the insulating layer made of one or both of amorphous carbon and hydrocarbon polymers to have pinholes or no pinholes, or pinholes in the photoelectric conversion film and one or both of amorphous carbon and hydrocarbon polymers. It is even rarer that pinholes or overlapping occur in an insulating layer made of either or both. Therefore, even if some holes exist in the partial area where the individual electrode wiring and the common electrode of the charge conversion membrane face each other, short circuits between the common electrode and the individual electrode wiring are prevented by the action of the insulating layer. .

Furthermore, since the insulating layer is composed of a thin film made of one or both of amorphous carbon and hydrocarbon polymer, this insulating layer and the IT
The manufacturing advantages described below can be obtained between transparent conductive films such as O and the like.

That is, etching for patterning the individual electrodes,
Thin films made of one or both of amorphous carbon and hydrocarbon polymers can be continuously deposited using the same plasma generator.

Furthermore, although it is not certain how each component functions in the method for manufacturing an image sensor according to the second invention of this application, it is thought to be as follows.

The hydrogen gas desorbs oxygen from the exposed portion of the transparent conductive film due to the resist button.

When the aliphatic hydrocarbons are plasma decomposed, radicals and ions of alkyl groups are generated. Then, the radicals and ions of the alkyl group combine with the gold 1 (for example, In or Sn when the transparent conductive film is ITO) in the transparent conductive film after the hydrogen has been desorbed, and gasify these metals.

As a result, dry etching of the transparent conductive film becomes possible.

In addition, by heating the sample, the gases of metals such as In, S, and N are promoted, making it possible to etch the transparent conductive film.

Further, since the flow of hydrocarbon gas is increased after the etching of the transparent conductive film is completed, a thin film made of one or both of amorphous carbon and a hydrocarbon polymer can be deposited satisfactorily.

(Example) Hereinafter, an example of an image sensor of the present invention and a method of manufacturing the same will be described using an example in which the present invention is applied to a reporter-type image sensor shown in FIG. Note that drawings are used for this explanation, and these drawings schematically show the dimensions, shapes, and distribution relationships of each component to the extent that the present invention can be understood. Furthermore, in each figure, constituent components similar to those shown in FIG. 3 are designated by the same numbers as those shown in FIG. M3.

First, the structure of the image sensor of the embodiment will be explained with reference to FIGS. 1(A) and 1(B). Here, in Figure 1 (A
) is a sectional view schematically showing the structure of the main part of the image sensor of the example, and FIG. 1(B) is a plan view. Figure 1 (A
) is II-I in FIG. 1(B).
This corresponds to an I-line cross-sectional view.

The image sensor of this embodiment includes a plurality of light receiving sections 19 having a common electrode 13, a photoelectric conversion film 15, and individual electrodes 17 in this order on a substrate 11, and further includes wiring for the individual electrodes connected to the individual electrodes 17. 21, and furthermore, between the photoelectric conversion film 15 and the individual electrode wiring 21, one of hydrogenated amorphous carbon (a-C: H) in this case as amorphous carbon (a-C) and a hydrocarbon polymer or It is characterized by having an insulating layer 31 made of both. Note that each light receiving section 19 is provided with a light guiding window 23 similar to the conventional one.

In this case, the substrate 11 is constituted by a substrate, for example, a glass substrate, which has an insulating property and is transparent to the light of a light source (for example, an LED array).

The common electrode 13 is made of a metal film having light-shielding properties, such as chromium.

The photoelectric conversion film 15 is made of, for example, hydrogenated amorphous silicon (
a-3i:H).

The individual electrodes 17 are made of a transparent conductive film such as ITO. Incidentally, it is preferable that the area of the individual electrode 17 is as small as possible within the range that allows for the characteristics of the photodiode and the desired customization of the image sensor. The area of the portion of the individual electrode connected to the wiring for the individual electrode (the portion indicated by Q in FIG. 1(A)) should also be made as large as necessary. By minimizing the area of 17 individual electrodes, the individual electrode 1
7 and the common electrode 13 can be reduced, and therefore, the frequency of occurrence of short circuits between the electrodes due to bottle balls of the photoelectric conversion film in this portion can be reduced.

Further, the individual electrode wiring 21 is made of, for example, aluminum.

Further, in this embodiment, the insulating layer 31 made of one or both of amorphous carbon and a hydrocarbon polymer is
It is provided over the entire area of the photoelectric conversion film 15 excluding the area where the individual electrodes 17 are provided, and over the glass substrate 11. This is despite the fact that such an M distribution relationship is obtained when a simple manufacturing process, which will be described later, is used. However, from a structural point of view, the insulating layer 31 may be provided between the photoelectric conversion film 15 and the individual electrode wiring 21.

Note that the photoelectric conversion film 15 and the individual electrode arrangement (herein referred to)
The darkness with 921 has the following meanings, for example, depending on the design of the image sensor.

For example, if the photoelectric conversion film 15 has an area that covers the common electrode 13 with a slightly larger area as shown in FIG. A short between the electrodes may also occur in the direction parallel to the main surface of the glass substrate 11 (the direction indicated by the middle day in FIG. 1(A)). Therefore, in such a case, the space between the photoelectric conversion film 15 and the individual electrode wiring 21 should be the entire area where the two face each other.

However, in the case where the planar area of the photoelectric conversion film 15 is sufficiently wider than that of the common electrode 13 and the photoelectric conversion film 15 is provided sufficiently outside the edge of the common electrode 13, the photoelectric conversion @ 15 and the wiring 21 for individual electrodes are different. 21 between the charge conversion membrane and the individual electrode wiring in the area facing each other.
It is sufficient to consider the area (area indicated by S in Figure 1 (A)) in which there is a possibility of occurrence of the show F between the common electrode 13 and the electrodes. Such a region may be determined at the time of element design.

Next, an example of the manufacturing method of the image sensor of the second invention will be explained using an example of manufacturing the image sensor of the example described using FIGS. 1 (Δ) and (B)%. I do. Figure 2 (
A) to (G) are process diagrams for explaining the process, and the first diagram shows the state of the image sensor during the main steps in the manufacturing process.
It is a process diagram shown with a sectional view at 100, corresponding to Figure (A). Note that it should be understood that the numerical conditions such as temperature, flow rate, film thickness, etc., and the conditions of the equipment used, etc., explained below are merely examples within the scope of the present invention.

First, chromium (Or) or nichrome (Ni) is deposited on the glass substrate 11 by a suitable method such as vacuum evaporation or sputtering.
A thin film of Cr) or the like is formed to a thickness of about 1,000 to 2,000 layers, for example. Next, the common electrode 13 is formed by patterning this thin layer into a predetermined shape using known two-dimensional lithography and etching techniques. Incidentally, during this patterning, the area 13a of the common electrode 13 corresponding to the area where the light guide window 23 is planned to be formed is also removed at the same time (Figure 2 (A)).
.

Next, by a glow discharge method using a raw material gas whose main component is silane gas, hydrogenated amorphous silicon, for example, 0.5 ml of hydrogenated amorphous silicon as the photoelectric conversion film 15 is selectively applied to a predetermined area on the glass substrate 11 with a common electrode. The film is deposited to a thickness of ~2 um (Fig. 2(B)).

Next, an ITO film as a transparent conductive film 41 is formed to a thickness of, for example, about 1000λ on the entire surface of the glass substrate 11 on which the photoelectric conversion film has been formed by sputtering (FIG. 2(C)).

Next, as a mask for patterning this ITO film into the shape of an individual electrode, a resist pattern 43 is formed on the ITO film 4 by a known photolithography method (FIG. 2(D)).

Next, the resist batten-formed sample is placed in a plasma generation device.

Next, without heating this sample, hydrogen and -bottom C, H
The resist baton 4 of the ITO film 41 is formed by a reaction/pouring dry etching jig using a hydrocarbon mixed gas represented by M.
3. (However, n in the above-mentioned bottom of the ship is an integer greater than or equal to 1, and m is an integer satisfying 4≦m≦2n+2.)

In this example, methane gas (
CH,)! The flow rate of methane gas was 1% 1 sccm, the flow rate of hydrogen gas was 1108 CC, and the power intensity was 0.
．． The ITO film 41 was etched under the conditions of 15 W/cm2 and a sample heating temperature (substrate heating temperature) of 160'C, thereby forming the individual electrodes 17 (Fig. 2 (E)).
), next, with the sample placed in the plasma generator as it is, the flow rate of hydrogen gas remains the same as when forming the individual electrodes, and the flow rate of methane gas! ! increase. In this example, the IT
The flow rate of methane gas, which was lsecm during etching of the O film, is increased to J1% and 30sccm. Note that the power density and substrate temperature are the same as when etching the ITO film.

When the conditions of the plasma generation device are set in this way, in the plasma generation device, the sample is made of one or both of amorphous carbon and hydrocarbon polymer: llJ
A film 45 is deposited (FIG. 2(E)). Note that the etching conditions for ITOH and the conditions for depositing a thin film made of one or both of amorphous carbon and a hydrocarbon polymer are not limited to the above-mentioned conditions. However, regarding the substrate heating temperature, if it is too low, the transparent conductive film cannot be etched well, and the quality of the thin film made of one or both of the amorphous capone and the hydrocarbon polymer deteriorates, and if it is too high, the substrate and ITO Problems that are thought to be caused by the difference in thermal expansion coefficient with the film (such as cracking in the ITO film), deformation of the resist batten, and difficulty in peeling off the resist may occur. Therefore, the substrate heating temperature is
The temperature is preferably within the range of 50 to 200'C, more preferably 150 to 200'C.

Next, the sample on which the thin film consisting of one or both of amorphous carbon and hydrocarbon polymer has been deposited is taken out from the plasma generator, and the resist batten 43 is peeled off to remove the amorphous material deposited on the resist batten 43. A desired insulating layer 31 is formed by simultaneously removing (one lift-off) the thin film portion made of one or both of carbon and hydrocarbon polymer (FIG. 2(G)).

Using a suitable method such as vacuum evaporation, sputtering, etc., a thin film (not shown) for forming wiring for individual electrodes, such as aluminum, etc.
The thin film is formed to a thickness of 2 um, and then this thin film is patterned into a predetermined shape using known photolithography and etching techniques to form the wiring 21 for individual electrodes. Subsequently, a light guiding window 23 is formed using known photolithography and etching techniques to obtain the image sensor of the embodiment shown in FIG.

In the above description, the embodiment of the image sensor of the first invention and the embodiment of the method of manufacturing an image sensor of the second invention have been described respectively, but these inventions are not limited to the above-mentioned embodiments and will be explained below. For example, each of the embodiments is an example in which the first invention and the second invention are applied to a complete nine-layer image sensor. It can be widely applied to image sensors having a structure in which individual electrode wiring C is sandwiched.

In addition, in the embodiment of the method for manufacturing an image sensor according to the second invention, the deposited thin film made of one or both of the amorphous carbon and the hydrocarbon polymer was patterned by lift-off, so that the insulating layer 31 was used for photoelectric conversion. A wide area remains on the glass substrate 11 and on the area excluding the area where the individual electrodes 17 of the film 15 are formed. However, if necessary, this insulating layer 31 or the photoelectric conversion film 15 and the individual electrode wiring 2 may be
You may further butter it so that it remains only at the gate with 1.

Further, in each of the examples, the transparent conductive film is IT○, but other materials may be used. Sn○2 instead of IT○
Alternatively, even when ZnO is used, etching of the transparent conductive film using a plasma generator and deposition of a thin film made of one or both of amorphous carbon and hydrocarbon polymer can be performed in the same manner as in the embodiment.

Furthermore, in the embodiment of the image sensor manufacturing method described above,
-Bottom〇-Hm (n is an integer greater than or equal to 1, m is 4≦m≦
An integer that satisfies 2n+2. ) is used as methane gas, or other hydrocarbons suitable for use in this invention are those that can generate radicals and ions of alkyl groups by plasma and gasify the metal in the transparent conductive film. It could be something like that. For example, ethane (CHe)
, propane (C3H1l), butane (C4H+o),
Even if ethylene (C2H,), propylene (C3H8), acetylene (C2H2), or the like is used, the same effects as in the examples can be expected.

(Effects of the Invention) As is clear from the above description, according to the image sensor of the first invention, if a pinhole exists in the partial area facing the individual electrode wiring and the common electrode of the photoelectric conversion film, However, due to the effect of the insulating layer, short circuits between the common electrode and the wiring for individual electrodes can be prevented, so the occurrence rate of bit defects can be reduced compared to the conventional method. Furthermore, since the insulating layer is composed of a thin film made of amorphous carbon and/or a hydrocarbon polymer, etching for patterning the transparent conductive film normally used as individual electrodes and deposition of the insulating layer are required. can be performed continuously using the same plasma generator.

Further, according to the method for manufacturing an image sensor of the second invention,
Etching for patterning the individual electrodes and deposition of a thin film made of one or both of amorphous carbon and a cladded wood-based material can be performed continuously by the same plasma generator.

Therefore, the image sensor of the first invention can be manufactured easily and inexpensively.

[Brief explanation of drawings]

Figures 1 (△) and (B) are cross-sectional views and plan views for explaining the image 7 sensor of the embodiment, and Figures 2 (A) to (G).
3A and 3B are process diagrams for explaining an example of a manufacturing method, and FIGS. 3A and 3B are a cross-sectional view and a plan view for explaining a conventional image sensor. 11... Substrate (e.g. glass substrate) 13... Common electrode (e.g. Cr film) 15... Photoelectric conversion film (θ1] for example a-3i17...
Individual electrode (for example, ITO electrode) 19...light receiving part H) 21... Wiring for individual electrode (for example, A9 film) 23...
Light guide window 31... Insulating layer 41 made of one or both of amorphous carbon and hydrocarbon polymer... Transparent conductive film (for example, ITO film) 43... Resist button 45... Amorphous carbon and hydrocarbon polymer A thin film consisting of one or both polymers. Applicant Oki Electric Industry Co., Ltd. (A) Photoelectric conversion film (e.g. a-3i:H) Individual electrode (e.g. ITOZi! pole) Wiring for individual electrode of light receiving part (e.g. AI2 film) Light guiding window amorphous cover and carbonization Cross-sectional view and plan view for explaining an image sensor of an embodiment of an insulating layer made of hydrogen-based polyester or both. Figure 2 Process for explaining an example of the manufacturing method Figure 2 (G)

Claims (2)

[Claims] (1) In an image sensor that includes a large number of light receiving elements having a common electrode, a photoelectric conversion film, and an individual electrode in this order on a substrate, and further includes wiring for the individual electrodes connected to the individual electrodes, the photoelectric conversion film and An image sensor comprising an insulating layer made of one or both of amorphous carbon (a-C) and a hydrocarbon polymer between the individual electrode wiring and the individual electrode wiring. (2) A large number of light receiving elements each having a common electrode, a photoelectric conversion film, and an individual electrode in this order are provided on a substrate, and wiring for the individual electrode connected to the individual electrode, and wiring for the photoelectric conversion film and the individual electrode are provided. In manufacturing an image sensor comprising an insulating layer made of one or both of amorphous carbon and a hydrocarbon polymer provided between wirings, the formation of the individual electrodes and the insulating layer is performed according to the following (A) and (B).
). (A) For individual electrodes, a transparent conductive film is deposited on the photoelectric conversion film, a mask is formed on the transparent conductive film to cover the area of the transparent conductive film that is to be the individual electrode, and then the mask is formed. The transparent conductive film is formed by placing the finished sample in a plasma generator, and etching the transparent conductive film by reactive dry etching using a mixed gas of hydrogen and a hydrocarbon represented by the general formula CnHm while heating the sample.
However, in the above general formula, n is an integer of 1 or more, and m is 4≦m≦
An integer that satisfies 2n+2. ). (B) Regarding the insulating layer, after forming the individual electrodes, the flow rate of the hydrocarbon gas is increased in the plasma generator to form a thin film made of either or both of amorphous carbon and a hydrocarbon polymer on the sample. is deposited, and then the sample is taken out from the plasma generator and the thin film is patterned and formed.