KR20160111671A

KR20160111671A - Image sensor and manufacturing method thereof

Info

Publication number: KR20160111671A
Application number: KR1020150036594A
Authority: KR
Inventors: 이동진; 임성일; 김태우
Original assignee: 주식회사 레이언스; (주)바텍이우홀딩스
Priority date: 2015-03-17
Filing date: 2015-03-17
Publication date: 2016-09-27

Abstract

The present invention provides a plasma display panel comprising: a substrate having a protective film and a pad electrode formed on a surface thereof; A photoconductive layer formed on the pad electrode and the protective layer; And an upper electrode formed on the photoconductive layer, wherein the pad electrode comprises a single layer structure of Ti or a multi-layer structure of the uppermost layer of Ti.

Description

Image sensor and manufacturing method thereof

The present invention relates to an image sensor, and more particularly, to an image sensor having improved adhesion between a photoconductive layer and a substrate, and a method of manufacturing the same.

Previously, film and screen were used in medical and industrial X-ray photography. In such a case, it was inefficient in terms of cost and time owing to the problem of development and storage of the photographed film.

In order to improve this, a digital image sensor is widely used today. The image sensor can be classified into an indirect conversion method and a direct conversion method.

The indirect conversion method uses a scintillator to convert X-rays into visible light, and then converts visible light into electrical signals. On the other hand, the direct conversion method converts X-rays directly into electrical signals using a photoconductive layer. Such a direct conversion method does not require the formation of a separate phosphor and does not cause spreading of light, and is suitable for a high-resolution system.

The photoconductive layer used in the direct conversion method is formed by being deposited on the surface of the CMOS substrate. However, the photoconductive layer has poor adhesion to the surface of the CMOS substrate. Thus, a defect that the photoconductive layer floats from the surface of the substrate can be generated.

Disclosure of the Invention Problems to be Solved by the Invention The present invention has a problem to provide a method for improving the adhesion between a photoconductive layer and a substrate.

According to an aspect of the present invention, there is provided a plasma display panel comprising: a substrate having a protective film and a pad electrode formed on a surface thereof; A photoconductive layer formed on the pad electrode and the protective layer; And an upper electrode formed on the photoconductive layer, wherein the pad electrode comprises a single layer structure of Ti or a multi-layer structure of the uppermost layer of Ti.

Here, the pad electrode formed in the multi-layer structure may have a lower layer made of Al or Cu in contact with the substrate.

In the pad electrode having the single layer structure or the multi-layer structure, the metal layer made of Ti may have a thickness of 20 nm to 500 nm.

And may include at least one metal layer of Ag, Au, Pt, and Pd, which is located between the protective layer and the photoconductive layer, and which is electrically disconnected from the pad electrode on the protective layer.

The metal layer may have a voltage or a floating state.

And another metal layer made of Cr between the protective film and the metal layer.

The photoconductive layer may be made of at least one of CdTe, CdZnTe, PbO, PbI _2, HgI _2, GaAs, Se, TlBr, BiI _3.

In another aspect, the present invention provides a method of manufacturing a semiconductor device, comprising: forming a pad electrode and a protective film on a surface of a substrate; Forming a photoconductive layer on the pad electrode and the protective layer; And forming an upper electrode on the photoconductive layer, wherein the pad electrode comprises a single layer structure of Ti or a multi-layer structure of a top layer of Ti.

According to the present invention, in the image sensor, Ti excellent in adhesion to the pad electrode in contact with the photoconductive layer is used. Thus, the adhesion between the photoconductive layer and the substrate can be improved.

Furthermore, a metal layer superior in adhesion to the protective film as compared with the photoconductive layer can be further formed between the photoconductive layer and the protective layer. Thus, the adhesion between the photoconductive layer and the substrate can be further improved.

1 and 2 are respectively a plan view and a sectional view schematically showing an image sensor according to a first embodiment of the present invention;
3 is a cross-sectional view schematically showing an image sensor according to a second embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

1 and 2 are respectively a plan view and a sectional view schematically showing an image sensor according to a first embodiment of the present invention.

As the X-ray imaging apparatus using the image sensor 200 according to the first embodiment of the present invention, X-ray imaging apparatuses of various forms and uses can be used. For example, various X-ray imaging apparatuses such as a mammography apparatus and a CT apparatus can be used.

The image sensor 200 corresponds to a configuration for detecting an X-ray passing through a subject and converting it into an electrical signal. The image sensor 200 has a rectangular shape in a plan view, but is not limited thereto.

In particular, the image sensor 200 according to the first embodiment of the present invention is an X-ray detecting element of a direct conversion system, and directly converts an incident X-ray into an electrical signal.

Referring to FIGS. 1 and 2, a plurality of pixel regions P may be arranged along a row line and a column line in a matrix form in the image sensor 200.

A photoelectric conversion element PC for converting an X-ray into an electrical signal can be formed on the substrate 210 in each pixel region P. [

Here, as the substrate 210 used for the image sensor 200, for example, a CMOS substrate, a glass substrate, a graphite substrate, a substrate formed by laminating ITO on an aluminum oxide (Al ₂ O ₃ ) base, or the like is used But is not limited thereto. In the embodiment of the present invention, for convenience of explanation, a case of using a CMOS substrate is taken as an example.

A protective film 215 is formed on the surface of the substrate 210. Protective film 215 is an inorganic insulating material, for example, be formed of a silicon oxide (SiO ₂₎ or silicon nitride (SiNx).

In the protective film 215, a pad hole 217 may be formed for each pixel region P. A pad electrode 220 may be formed in the pad hole 217.

The pad electrode 220 corresponds to, for example, the first electrode 220 as one electrode constituting the photoelectric conversion element PC.

The first electrode 220 may have a single-layer structure or a multi-layer structure. 2 illustrates an example in which the first electrode 220 is formed in a multilayer structure, that is, a two-layer structure.

The first electrode 220 having a two-layer structure may include a lower first metal layer 221 and an upper second metal layer 222.

As the first metal layer 221, Al or Cu is used as a low-resistance material having a low resistance. Al and Cu have characteristics that the adhesion property to the upper photoconductive layer 240 is poor.

On the other hand, the second metal layer 222 is in direct contact with the upper photoconductive layer 240, and is formed of Ti, which is excellent in adhesion to the photoconductive layer 240. That is, Ti has a significantly higher adhesive force with the photoconductive layer 240 than Al or Cu.

As described above, the first electrode 220 directly contacting the photoconductive layer 240 is made of the metal layer 222 made of Ti, so that the adhesion of the photoconductive layer 240 to the substrate can be improved.

In this connection, when comparing the experimental values of the adhesion of the photoconductive layer 240 in the case where Ti is not used and in the case of using Ti as in the case of the prior art, The adhesive strength is 4B level (adhesion strength of 5% or less of the total area), and when Ti is used, the bonding strength is 0B level (95% of the total area).

Therefore, by applying the metal layer 222 formed of Ti to the portion of the first electrode 220 which directly contacts the photoconductive layer 240 as in the first embodiment of the present invention, The adhesion is improved to a superior level.

On the other hand, the first metal layer 221 made of Al or Cu is preferably formed to a thickness of about 1 um or less. The second metal layer 222 made of Ti is preferably formed to a thickness of about 20 nm to 1 um, more preferably about 20 nm to 500 nm.

The second metal layer 222 made of Ti may be formed by a vacuum deposition method such as sputtering or evaporation, or an electrochemical method such as plating.

In the above description, the case where the first electrode 220 has a multilayer structure has been described as an example. As another example, the first electrode 220 may have a single layer structure. In such a case, the first electrode 220 may be formed of Ti, which has excellent adhesion to the photoconductive layer 240.

A photoconductive layer 240 is formed on each of the pixel regions P on the first electrode 220 and the protective film 215.

When the X-ray is incident, the photoconductive layer 240 generates an electron-hole pair. As the photoconductive layer 240, a material capable of having characteristics of excellent charge transfer characteristics, high absorption coefficient, low dark current, and low electron-hole pair generation energy can be used. For example, a CdTe, CdZnTe, PbO, PbI _2, HgI _2, GaAs, Se, TlBr, at least one of the light conductive material, such as a group BiI ₃ is used.

The photoconductive layer 240 may be formed to have a thickness of about 100 袖 m to about 1000 袖 m, but the present invention is not limited thereto.

The upper electrode 250 may be formed on the substrate 210 on which the photoconductive layer 240 is formed. A bias voltage may be applied to the upper electrode 250.

The upper electrode 250 corresponds to the second electrode 250 as the other electrode constituting the photoelectric conversion element PC. The second electrode 250 may be formed substantially over the entire surface of the substrate 210.

The second electrode may be formed of Au or Pt, but is not limited thereto.

As described above, in the image sensor according to the first embodiment of the present invention, Ti excellent in adhesion to the pad electrode in contact with the photoconductive layer is used. That is, the pad electrode may be formed of a Ti single layer or the uppermost layer may be formed of a Ti layer.

This improves the adhesion between the photoconductive layer and the substrate, and improves the adhesion of the photoconductive layer.

3 is a cross-sectional view schematically showing an image sensor according to a second embodiment of the present invention.

In the following description, a detailed description of a similar configuration to the first embodiment can be omitted.

Referring to FIG. 3, the image sensor 200 of the second embodiment may further include a metal layer 230 formed on the protective film 215. For convenience of explanation, the metal layer 230 formed on the protective film 215 is referred to as a third metal layer 230.

The third metal layer 230 may be made of a material having excellent adhesion to the protective film 215. For example, the third metal layer 230 may include silver (Ag), gold (Au), platinum (Pt), palladium And a noble metal material group.

The third metal layer 230 is formed between the protective film 215 and the photoconductive layer 240 formed in the subsequent process so that the adhesion of the photoconductive layer 240 to the substrate 210 can be improved .

That is, the photoconductive layer 240 has a poor adhesion to the protective layer 215 using silicon nitride. In such a case, the third metal layer 230 can play a more effective role in improving the adhesion.

The third metal layer 230 made of a noble metal material may be spaced apart from the first electrode 220 and electrically disconnected. That is, in each pixel region P, the third metal layer 230 may be formed on at least a part of the periphery of the first electrode 220 in a plan view. Here, the third metal layer 230 may be configured to have an area of approximately 10% to 90% of the total area of the pixel region P. [

Meanwhile, the third metal layer 230 may function not only to improve the adhesion of the photoconductive layer 240 to the substrate, but also to function to reduce the leakage current by concentrating the electric field between the second electrode 250 and the first electrode 220 .

The third metal layer 230 is formed around the first electrode 220 so that an electric field generated between the second electrode 250 and the first electrode 220 is applied to the third metal layer 230 Thereby being able to be guided in the inward direction. As such, the third metal layer 230 can serve as a guard ring for electric field formation.

For this purpose, the third metal layer 230 may be configured with a voltage or a floating state.

A metal layer 235 formed of Cr, that is, a fourth metal layer 235 may be formed between the third metal layer 230 and the protective film 215 to improve adhesion between the third metal layer 230 and the protective film 215. That is, the fourth metal layer 235 can be formed using Cr having a higher adhesive force than the third metal layer to the protective film 215.

As a result, the adhesion of the photoconductive layer 240 to the substrate can be further improved.

On the other hand, the total thickness of the third and fourth metal layers 30 and 235 may be about 10 nm to 200 nm.

As described above, according to the embodiments of the present invention, Ti which is excellent in adhesion to the pad electrode in contact with the photoconductive layer is used in the image sensor. Thus, the adhesion between the photoconductive layer and the substrate can be improved.

The embodiment of the present invention described above is an example of the present invention, and variations are possible within the spirit of the present invention. Accordingly, the invention includes modifications of the invention within the scope of the appended claims and equivalents thereof.

200: image sensor 210: substrate
215: protective film 217: pad hole
220: pad electrode 221: first metal layer
222: second metal layer 230: third metal layer
235: fourth metal layer 240: photoconductive layer
250: upper electrode

Claims

A substrate on which a protective film and a pad electrode are formed;
A photoconductive layer formed on the pad electrode and the protective layer;
And an upper electrode formed on the photoconductive layer,
The pad electrode may be formed of a single layer structure of Ti or a multi-layer structure of the uppermost layer of Ti
Image sensor.

The method according to claim 1,
The pad electrode formed in the multilayer structure has a lower layer made of Al or Cu in contact with the substrate
Image sensor.

The method according to claim 1,
In the pad electrode of the single layer structure or the multi-layer structure, the metal layer made of Ti has a thickness of 20 nm to 500 nm
Image sensor.

The method according to claim 1,
At least one metal layer of Ag, Au, Pt, and Pd, which is located between the protective film and the photoconductive layer, and which is electrically disconnected from the pad electrode,
.

5. The method of claim 4,
The metal layer may be either a voltage applied or a floating state
Image sensor.

5. The method of claim 4,
And another metal layer made of Cr between the protective film and the metal layer
.

The method according to claim 1,
The photoconductive layer is of CdTe, CdZnTe, PbO, PbI _2, HgI _2, GaAs, Se, TlBr, BiI ₃ consisting of at least one
Image sensor.

Forming a pad electrode and a protective film on the surface of the substrate;
Forming a photoconductive layer on the pad electrode and the protective layer;
And forming an upper electrode on the photoconductive layer,
The pad electrode may be formed of a single layer structure of Ti or a multi-layer structure of the uppermost layer of Ti
Method of manufacturing an image sensor.