Silver alloy material, circuit substrate, electronic device, and method for manufacturing circuit substrate

Abstract

A circuit substrate of the present invention uses as component materials for gate lines and gate electrodes, silver alloy material containing silver as a main component, and at least one element selected from the group consisting of tin, zinc, lead, bismuth, indium, and gallium. It is especially preferable that the silver alloy material mainly consisting of silver and containing indium is used for the gate lines and the gate electrodes. With this, it is possible to provide silver alloy material whose resistance value, adhesion, plasma resistance, and reflection characteristics can be appropriately adjusted by the adjustment of the content of indium. Further, it is also possible to apply the alloy in accordance with the characteristic required for each part of the circuit substrate.

Description

[0001] This Nonprovisional application claims priority under 35 U.S.C. § 119(a) on Patent Application No. 200806 / 2003 filed in Japan on Jul. 23, 2003, Patent Application No. 200815 / 2003 filed in Japan on Jul. 23, 2003, Patent Application No. 185228 / 2004 filed in Japan on Jun. 23, 2004, and Patent Application No. 185264 / 2004 filed in Japan on Jun. 23, 2004, the entire contents of which are hereby incorporated by reference. FIELD OF THE INVENTION [0002] The present invention relates to a silver alloy material. The present invention relates in particular to a silver alloy material which composes lines and / or electrodes on a circuit substrate that uses an insulation substrate; a circuit substrate whose lines and / or electrodes are formed using either the above-mentioned material or fluid material such as silver alloy fluid; a method for manufacturing the circuit substrate; and an electronic device using the circuit substrate, such as a display device, a liquid crystal display device, and...

AI Technical Summary

Benefits of technology

[0023] The present invention has an objective to provide a silver alloy material that can realize a material having heat resistance and strong adhesion to a glass substrate as well as high plasma resistance and good light reflectance. The present invention also has an objective to provide a circuit substrate that can obviate a multi-layer structure of thin films so as to prevent the increase in the number of steps and cost for manufacturing the circuit substrate; a method for manufacturing the circuit substrate; and an electronic device.

[0024] As a result of assiduous study in order to achieve the foregoing objectives, the inventors of the present invention found that in a case where particles of alloy containing silver as its main component and indium are used as a material for forming lines or electrodes on an insulation substrate, the adhesion of the lines and electrodes to the insulation substrate, as well as the heat resistance and plasma resistance of the lines and electrodes improved, compared with a case where particles consisting only silver is used as a material for forming the lines or electrodes on the insulation substrate. Further, the inventors found that the similar effects can be achieved by using alloy in which tin, zinc, lead, bismuth, or gallium, instead of indium, is added to silver.

[0025] Further, the inventors of the present invention found that it is possible to obtain a silver alloy film retaining high visible light reflectance after baked at 200° C. or at 300° C. by adding an appropriate amount of indium to silver. Further, the inventors found that, because the silver alloy film as described above has high reflectance as a whole compared with aluminum conventionally used for a light reflecting film, brighter display can be achieved when the silver alloy film is used as light reflective electrodes, etc., in a reflection type liquid crystal display device, for example.

[0028] Further, as a result of assiduous study, the inventors of the present invention found that it is possible to reduce the number of steps and cost for manufacturing a circuit substrate by adjusting the characteristics of a same line in accordance with the characteristic required for each part of the line.

[0031] It is possible to change characteristics of one portion from another in the same line by causing the portions to have different composition ratios from one another, or by causing the portions to have different component materials from one another.

Problems solved by technology

Accordingly, a huge cost of equipment is required in the manufacturing of TFT array substrates in response to recent demands for TFT array substrates having larger size.

However, the usable range of silver is limited because of the properties of silver.

Silver significantly lacks heat resistance.

If silver is formed into a film on a glass substrate using an evaporation method, a sputtering method, or other methods, for example, the silver film generates grain growth and clouded surface when baked at about 250° C. Further, silver has weak adhesion to the glass substrate.

Therefore silver cannot be directly used as a material for forming the lines on TFT array substrates.

Further, conventional silver has low heat resistance, and the reflectance of the silver is remarkably lowered after the silver is baked at 200° C., for example.

Hence, conventional silver cannot be used if heat resistance is required during the manufacturing process.

For example, it has been difficult to use silver as a material for a light reflecting film provided on a TFT array substrate in a reflection type liquid crystal display device, for example.

However, it is difficult for one type of material to cover all of the performances as described above.

This is a notable material for the lines on the circuit substrate, but has a limited range of usage because of the properties of the material.

Silver significantly lacks heat resistance depending on temperature.

However, silver as an application material, in particular, cannot have an effect of implanting into the substrate when formed into the film.

Consequently, the silver has weak adhesion to the glass substrate, thus having problems in processability and stability.

Further, if the baking is used to improve the adhesion, the surface flatness of the silver film deteriorates due to the grain growth properties of silver as described above.

Further, there is also a problem in using silver to form lines on a TFT array substrate.

When exposed to plasma in the dry etching gas, the silver film is deteriorated and separated because of oxidation, etc.

Therefore there is a problem in immediately using silver as the wiring material.

In other words, there is a problem that thin films are layered on the insulation substrate.

This increases the number of steps for manufacturing the circuit substrate, thereby increasing the cost.

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