JP2002110678A - Ag ALLOY, Ag ALLOY THIN FILM AND, THIN-FILM TRANSISTOR USING THE SAME, AND THIN-FILM TRANSISTOR ARRAY AND MANUFACTURING METHOD OF THEM - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problems of the adhesive properties of a substrate board, surface oxidation of a film due to a later step, when an Ag alloy film is used as a gate metal film of an amorphous silicon thin film transistor. SOLUTION: The adhesive properties of the film are improved by subjecting it to reverse sputtering of the surface of the substrate before the film formed by using a nitrogen gas, when a gate metal Ag alloy film is formed. After the pattern of the gate metal Ag alloy film has been formed, the surface of the film is reversely sputtered or plasma treated to prevent a deterioration of characteristics, due to the oxidation of the Ag alloy film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an active matrix type liquid crystal display (LCD) and a thin film transistor (Thin Film Transistor) used for a memory integrated circuit.
or: Hereinafter, abbreviated as TFT. ), A wiring electrode used for an organic EL, and the like and a method of manufacturing the same.

[0002]

2. Description of the Related Art As shown in FIG. 2, a conventional thin film transistor has a gate metal film 2 of a predetermined shape on a light-transmitting substrate 1, a gate insulating film SiNx film 3, an amorphous silicon film 4, and a gate metal film 2. An n + Si film 5 for making contact with the source and drain electrodes is continuously formed.
A source / drain metal film 6 having a predetermined shape is formed thereon. A SiNx film is formed thereon as a passivation film 7, and an ITO film of a transparent conductive film 8 that is in contact with the drain metal via a contact hole is formed thereon. A as the gate metal film
In recent years, g-based alloy films have been receiving attention. The Ag-based alloy film can be made into a single-layered gate metal film in that it does not cause thermal diffusion or battery phenomena in the electrolyte even when it comes into contact with silicon or ITO film, and it is expected that the process can be simplified. ing.

[0003]

However, when an Ag-based alloy film is used as the gate metal film 2, the adhesion to a light-transmitting substrate such as glass is poor, and the A
There was a problem that the g alloy film was peeled off. On the other hand, the Ag alloy film is easily oxidized by oxygen plasma, and when an ashing step or the like is performed after pattern formation, there is a problem that the wiring is blackened and the resistance is increased.

The present invention solves these problems of the prior art, and does not peel or oxidize during the process and has a high stability, that is, a gate wiring of a thin film transistor capable of producing a large-area display with a high yield. The purpose is to provide a structure. Note that these wiring electrodes are not limited to thin film transistors, but are also used as electrodes for organic EL or the like.

[0005]

According to the thin film transistor of the present invention, in order to improve the adhesion between the Ag-based alloy film and the underlying substrate, the nitrogen content of the underlying substrate at the interface between the Ag-based alloy film and the Ag-based alloy film is reduced. More than the nitrogen content inside the base alloy film. At this time, it is desirable that the nitrogen content at the interface be two orders of magnitude greater than that inside the film. In the formation method, the surface of the base substrate is previously subjected to nitriding by reverse sputtering using nitrogen plasma or nitrogen gas. on the other hand,
In order to prevent oxidation of the Ag-based alloy film, a large amount of nitrogen is contained in the interface between the Ag-based alloy film and the gate insulating film. In the formation method, after the formation of the Ag-based alloy film, the film surface is subjected to reverse sputtering using nitrogen plasma or nitrogen gas.

The operation of the present invention will be described below.

[0007] By increasing the nitrogen content of the underlying substrate at the interface with the Ag-based alloy film, the adhesion of the Ag-based alloy film is improved, and nitrogen is present at the interface of the Ag-based alloy film with the gate insulating film. By including a lot,
The oxidation of the Ag-based alloy film during the process can be prevented.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an example of a thin film transistor of the present invention. FIG. 3 shows an example of a manufacturing process of the thin film transistor of the present invention. As shown in FIG. 1, in order to nitride the surface of the translucent substrate 1, before forming a gate metal film, reverse sputtering is performed using nitrogen gas at 100 to 300 W for about 30 seconds, and then an Ag-based alloy thin film is formed. 2 is formed to a predetermined thickness.

Next, a gate insulating film 3 made of a SiNx film
330 nm and amorphous silicon film 4 200 n
m, n + amorphous silicon film 5
After being formed by the ECVD method, it is processed into a predetermined shape. Thereafter, a Ti / Al / Ti film 6 or the like is formed as a source / drain electrode and then processed into a predetermined shape. Passive
A 300 nm thick SiNx is formed as the option film 7. Thus, a thin film transistor is formed.

In order to form a thin film transistor array, after a contact window is formed in the passivation film 7, an ITO transparent conductive film 8 is formed to a thickness of 750 nm. The array is completed by processing the pixel electrode into a predetermined shape.

FIG. 4 shows the variation of the resistance of the gate electrode wiring between the twelve thin film transistor substrates of the present invention and the conventional variation of the resistance of the gate electrode wiring between the twelve transistors, for comparison. Note that the average value of the resistances of the twelve gate electrode wires of the thin film transistor of the present invention is set to 100, and the variation in the resistance of each substrate is shown. It can be seen that in the present invention, the variation in resistance is very small and the reproducibility is good as compared with the conventional case.

On the other hand, thin films having different nitrogen concentrations at the interface were prepared by reverse sputtering or plasma treatment with nitrogen gas before the formation of the Ag-based alloy film, and the adhesion was evaluated by a tape test. After pattern formation, reverse sputtering or plasma treatment with nitrogen gas was performed in the same manner as in the pretreatment before film formation, and then the resistance was measured to evaluate the resistance. The results are shown in (Table 1).

[0013]

[Table 1]

From Table 1, it can be seen that Ag was reversely sputtered at the interface with the underlying substrate with nitrogen gas or after plasma nitriding.
Nos. 4, 5, 9, 10, 14 to 1 in which a base alloy thin film was formed and the nitrogen concentration at the interface of the underlying substrate was higher than that in the alloy film
In Sample No. 7, samples Nos. 2, 3, 7, 8, 12, and 13 in which the nitrogen concentration at the base interface of the Ag alloy film was higher than in the alloy film.
Thus, an Ag-based alloy film having good adhesion could be formed. Also, after forming the Ag-based alloy film pattern and before forming the gate insulating film, nitrogen gas reverse sputtering or plasma nitridation was performed so that the nitrogen concentration on the alloy film surface was higher than that in the film.
o. In 6 to 17, damage during process (oxidation of alloy film)
Can be prevented, and a resistor having a relatively low resistance value is obtained.

The present inventors have also conducted similar studies on samples in which the composition (Ag, Pd, Cu, N) of the Ag alloy film is variously changed, but Pd and Cu are each at least 0.05 at%. If the nitrogen content is 5 at% or less and the nitrogen content is in the range of 0.1 to 1 at%, it is possible to form an Ag-based alloy film having good adhesion to the substrate by increasing the nitrogen concentration at the interface of the underlying substrate to be higher than in the alloy film. In addition, when the nitrogen concentration on the surface of the Ag-based alloy film was higher than that in the film, a thin film transistor having less process damage and no change in resistance during the process was obtained, and as a result, a thin film transistor having good characteristics was obtained. Nitriding of the interface between the base and the surface was similarly effective for the source / drain electrodes.

The Ag-based alloy of the present invention has high stability without being peeled or oxidized during the process even when the Ag-based alloy is used for a metal film or wiring. Further, when this Ag-based alloy film is used as a gate metal film of a thin film transistor, it is possible to provide a gate wiring structure of the thin film transistor capable of forming a large-area display with a high yield.

[Brief description of the drawings]

FIG. 1 illustrates an example of a thin film transistor of the present invention.

FIG. 2 illustrates an example of a conventional thin film transistor.

FIG. 3 is a diagram showing an example of a process flow of the thin film transistor of the present invention.

FIG. 4 is a diagram showing variations in gate wiring resistance of the thin film transistors of the present invention and the conventional invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 translucent substrate 2 gate metal film (AgPdCu) 3 gate insulating film (SiNx) 4 amorphous silicon film 5 n + Si film 6 source / drain metal film 7 passivation film SiNx 8 transparent conductive film

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) // C22C 5/06 G02F 1/136 500 5/08 H01L 29/78 617M (72) Inventor Mikihiko Nishitani Osaka 1006, Kazuma, Kamon, Fumonma-shi Matsushita Electric Industrial Co., Ltd.F-term (reference) NA28 PA07 4M104 BB08 BB39 CC05 DD22 DD89 GG20 HH09 5C094 AA32. NN72 QQ09

Claims (17)

[Claims] 1. An Ag-based alloy comprising Ag as a main component and having a higher nitrogen content at the interface than at the inside. 2. A method according to claim 1, wherein said substrate is formed on a substrate containing Ag as a main component.
An Ag-based alloy thin film, characterized in that the interface between the substrate and the Ag-based alloy thin film contains two or more digits of nitrogen from the inside of the substrate. 3. The method according to claim 1, wherein the substrate is formed on a substrate containing Ag as a main component.
An Ag-based alloy thin film, wherein the Ag-based alloy thin film contains nitrogen at an interface with an underlying substrate by two digits or more from the inside of the film. 4. An Ag-based alloy thin film containing Ag as a main component and containing nitrogen by two orders of magnitude or more at the interface side with the upper layer film than the internal content of the film. 5. An Ag-based alloy thin film containing two or more digits of nitrogen at the interface with the underlying substrate and at the interface with the upper layer film more than inside the substrate. 6. An Ag-based alloy thin film containing two or more digits of nitrogen at the interface between the underlying substrate and the Ag-based alloy and between the interface with the upper layer film. 7. An Ag-based alloy thin film containing two or more digits of nitrogen at the interface between the underlayer substrate and the upper layer film from the inside of the substrate, and whose concentration changes in a gradient manner. 8. The Ag-based alloy thin film according to claim 1 is formed on a light-transmitting substrate as a gate metal film, and a Si metal thin film is formed thereon.
An Nx gate insulating film, an a-Si semiconductor film, an n + Si film, and a source / drain electrode are laminated, and the nitrogen content at the interface between the under translucent substrate and the Ag-based alloy thin film is the Ag content. A thin film transistor characterized by being two or more digits larger than the inside of the alloy thin film. 9. The Ag-based alloy thin film according to claim 1 is formed on a light-transmitting substrate as a gate metal film, and a Si metal thin film is formed thereon.
An Nx gate insulating film, an a-Si semiconductor film, an n + Si film, and a source / drain electrode are laminated, and the nitrogen content at the interface between the Ag-based alloy thin film and the underlying translucent substrate is the same as that of the Ag alloy. A thin film transistor characterized by being two or more digits larger than the inside of the thin film. 10. The Ag-based alloy thin film according to claim 1 is formed on a light-transmitting substrate as a gate metal film, and S
An iNx gate insulating film, an a-Si semiconductor film, an n + Si film, and a source / drain electrode are laminated, and the nitrogen content at the interface between the Ag-based alloy thin film and the SiNx gate insulating film is the Ag alloy thin film. A thin film transistor characterized by being two or more digits larger than the inside. 11. An Ag-based alloy thin film according to claim 1 is formed as a gate metal film on a light-transmitting substrate.
Ag-based alloy in which an iNx gate insulating film, an a-Si semiconductor film, an n + Si film, and a source / drain electrode are laminated, and nitrogen is contained in the interface between the underlying substrate side and the upper layer film at least two orders of magnitude more than inside the substrate. A thin film transistor having a thin film. 12. An Ag alloy gate metal film according to claim 1 is formed on a translucent substrate, and a SiNx gate insulating film, an a-Si semiconductor film, an n + Si film, and source / drain electrodes are laminated thereon. A of the base translucent substrate
A thin film transistor, wherein the nitrogen content at the interface with the g-based alloy thin film and the nitrogen content at the interface with the gate insulating film are at least two orders of magnitude greater than inside the Ag alloy thin film. 13. The Ag-based alloy thin film according to claim 1 is formed as a gate metal film on a light-transmitting substrate, and S
An iNx gate insulating film, an a-Si semiconductor film, an n + Si film, and a source / drain electrode are stacked, and nitrogen is contained in the interface between the underlying substrate and the upper layer film at least two orders of magnitude greater than the inside of the substrate, and A thin film transistor having an Ag-based alloy thin film whose concentration changes in a gradient manner. 14. The nitrogen content is adjusted by nitriding the surface of the transparent substrate or the surface of the Ag alloy gate metal film with nitrogen plasma. A method for manufacturing the thin film transistor according to the above. 15. The nitrogen content is adjusted by reverse-sputtering the surface of the translucent substrate or the surface of the Ag alloy gate metal film with a nitrogen gas. 3. The method for manufacturing a thin film transistor according to item 1. 16. A thin-film transistor array comprising the thin-film transistor according to claim 8 and pixel electrodes arranged in a matrix. 17. A thin-film transistor array comprising: the thin-film transistor according to claim 8; a pixel electrode for driving liquid crystal; and a step of forming a gate line and a source bus line. Production method.