氫氣電漿對低溫複晶矽薄膜電晶體的鈍化效應之研究

Abstract

本論文主要研究氫氣電漿鈍化後之低溫、n-型通道複晶矽(最高製程溫度 為攝氏600度)薄膜電晶體的特性。藉由氫氣電漿對能隙中的捕獲能位的鈍 化效應，改善元件的特性，可使低溫複晶矽薄膜電晶體，具有移動率 32cm2/Vsec、臨界電壓約3V、最大的開/關電流比率達1.8e6的基本特性。 其能隙中捕獲能位的密度，大約降至原來(未經氫氣鈍化)的9%，臨界電壓 亦隨之降低。此外，氫氣電漿對低溫複晶矽薄膜電晶體的鈍化效應與動力 機構，亦同時被探討。兩種不同型態的缺陷結構，能藉由電晶體的電性參 數隨著氫氣電漿鈍化後的提昇過程而加以區別，亦在本文中加以提出。 The reduction of trap-state density by plasma hydrogenation of n-channel polysilicon thin film transistors (poly-Si TFT's) fabricated using a maximum temperature of 600(C has been studied. Hydrogenated devices have a mobility of 32 cm2/Vsec,a threshold voltage of ~3V, and a maximum ON/OFF current ratio of 1.8e6.Trap- state density decreases to about 9% of the value of the as-fabricated devices, concomitant with the reduction of threshold voltage.In addition, the effect and kinetics of the hydrogen passivation on polysilicon thin film transistors were also investigated. Based on the response of device parameters with the progress of hydrogenation, two types of defects can be distinguished from the difference in the passivation rate.