透明非晶態氧化鋅錫搭配無銦電極之薄膜電晶體

Abstract

由於銦價不斷的上漲，氧化薄膜電晶體中無銦的材料逐漸受到重視。本文著墨於無銦的非晶態氧化鋅錫薄膜電晶體的薄膜特性、光學特性、電性特性、穩定度以及抗蝕刻特性的研究，同時也與氧化銦鎵鋅薄膜電晶體做比較與討論。為了實現整個元件都無銦，在透明電極材料上使用氧化鋁鋅做為源極與漏極搭配氧化鋅錫薄膜電晶體的特性也做了完整的研究與比較。 實驗結果顯示氧化鋅錫電晶體因為有低的有效電子質量與較高的載子濃度，所以有較高的載子移動率，且在穩定度上因為氧化鋅錫有較大的電負度，所以在正偏壓應力與高溫下有較高的穩定性。而抗刻蝕刻力的結果顯示氧化鋅錫的抗蝕刻性是氧化銦鎵鋅的8.4倍，這將有利於濕式蝕刻的製程。本研究的結果指出無銦的非晶態氧化鋅錫薄膜電晶體有潛力作為高性能非金態氧化物的薄膜電晶體。

Oxide thin film transistors (TFTs) based on Indium-free materials are in high demand due to the price of In increase substantially. To solve those issues, zinc oxide (ZnO) based semiconductor materials are introduced and studied. Present study aims to develop the In-free metal oxide TFTs and discusses the characteristics of amorphous Zn-Sn-O (a-ZTO) TFTs, including thin film qualities, optical properties, electrical properties, stabilities, and etching resistance. Also, the comparisons of a-ZTO and amorphous In-Ga-Zn-O (a-IGZO) TFTs are presented. To realize the In-free TFTs, the a-ZTO TFTs with transparent conductive oxide Al-Zn-O (AZO) is used as source and drain electrodes. The electrical results demonstrate that the mobility of a-ZTO TFT is higher than a-IGZO TFT, because a-ZTO has the lower effective mass and the higher carrier concentration. A-ZTO has the higher electronegativity in stronger metal oxide bonding than a-IGZO that results in better stability under a temperature bias stressing. A-ZTO has a factor of 8 higher in etching resistance compared to that of a-IGZO, thus, more easily forming high quality patterns definition in wet etching process. These results imply that a-ZTO TFT is promising to be high performance In-free TFTs.