Netsu Sokutei, 35 (2), p. 81, (2008)



Application of Thermal Analysis to Optimization of Preparation Process of Indium-Tin-Oxide Thin Films

薄膜の熱分析が可能かつ有用な例として,多結晶およびアモルファスのスズ添加酸化インジウム(indium-tin-oxide; ITO)透明導電膜の加熱変化を昇温脱離ガス分析法(temperature programmed desorption; TPD)および高温X線回折法(high-temperature X-ray diffraction analysis; HT-XRD)で検討した結果を解説する。ITO膜が放出する主たるガスは水蒸気で、放出量は緻密な結晶性薄膜に比べて多孔質の結晶性薄膜の方が多い。アモルファス薄膜を加熱した際には水蒸気が放出された。その原因は,アモルファス薄膜中に存在するIn-OHまたはSn-OH結合が結晶化の際に切断されるためと推定した。スパッタ成膜する際の水蒸気分圧を制御することによってアモルファスITO膜の結晶化の抑制が可能なことが高温X線回折によって示された。
The present article introduces that thermal analysis of thin films are possible and useful. Thermal change of crystalline and amorphous indium-tin-oxide (ITO) transparent conducting films was investigated by temperature programmed desorption (TPD) and high-temperature X-ray diffraction (HT-XRD). Water vapor was the main gas released from the all films. Porous crystalline films released more water vapor than those from the dense ones. The thermal crystallization of amorphous films accompanied fast release of large amount of water vapor, which was attributed to disappearance of In-OH and Sn-OH bonds. The in-situ measurement of the crystallization process by HT-XRD analysis revealed that the thermal crystallization could be suppressed by the optimization of water vapor pressure during the sputter-deposition.