AVS 50th International Symposium
    Thin Films Tuesday Sessions
       Session TF-TuM

Paper TF-TuM7
Properties of Indium Zinc Oxide Thin Films on Heat Withstanding Plastic Substrates

Tuesday, November 4, 2003, 10:20 am, Room 329

Session: Thin Films on Organic, Polymeric and Biological Substrates
Presenter: H. Hara, Teijin Ltd., Japan
Authors: H. Hara, Teijin Ltd., Japan
T. Hanada, Teijin Ltd., Japan
T. Shiro, Teijin Ltd., Japan
T. Yatabe, Teijin Ltd., Japan
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Accompanying with downsizing and improving of resolution of various display devices, a heat withstanding plastic substrates with low resistivity of transparent conductive oxide (TCO) films have been demanded. We succeeded in development of optical anisotropy transparent plastic substrates with high glass transition temperature over 200 degC. However, tin doped indium oxide (ITO) films used as the transparent conductive electrode have high resistivity about 5E-4 ohm cm because the deposition of ITO films was carried out by sputtering at room temperature to avoid the out gassing from the plastic substrate. This kind of ITO films arise the amorphous/crystal transformation (a/c transformation) at 150 degC. The a/c transformation makes the ITO films crack with increase in resistivity. Then, we have been investigated new transparent conductive oxide films with low resistivity for our heat tolerance plastic substrate. We found that 7.5 wt% ZnO doped indium oxide (IZO(7.5)) films are suitable for the plastic substrates by surveying the ZnO content preciously. IZO(7.5) films deposited at room temperature by conventional dc-magnetron sputtering exhibited the low resistivity, 2.9E-4 ohm cm, keeping the high transparency, over 86 %. By using XRD and TEM, it is revealed that IZO(7.5) films were remained the structure in amorphous after annealing. Moreover, the result of thermal properties of IZO(7.5) films by DSC was elucidated that the a/c transformation was occured at 350 degC. The etching rate to 3.5 wt% HCl of IZO(7.5) films were 2 nm/sec. It is almost as same as or quicker than that of amorphous ITO films. The durability to 5 wt% KOH solution is also good for practical use. We have already succeeded in deposition of IZO(7.5) film on our heat withstanding plastic substrate with 1000 mm width and 500 m length. This substrate with IZO(7.5) film can remain the all properties after 180 degC annealing.