低溫多晶矽技術對多晶矽奈米線薄膜電晶體通道結晶特性影響之研究

Abstract

本論文研究應用低溫多晶矽(LTPS)技術，製造具有多晶矽奈米線通道之薄膜電晶體。快速熱退火(RTA)是一種具有材料選擇性加熱的技術，應用於金屬誘發側向結晶法(MILC)時，除了可以大幅降低元件製程時間和熱積存問題，更能增加複晶矽橫向結晶的速度；然而，固相結晶(SPC)機制的發生卻會使MILC反應受到阻礙，藉由調整RTA製程溫度與持溫時間，討論元件特性造成的影響；並從材料、電性分析和活化能等參數萃取，探討成核開口配置及不同結晶方法製備奈米線通道薄膜電晶體的差異。另外，當電晶體佈局為複數通道時，不同多晶矽結晶技術將會對元件通道多晶矽品質產生變異性，進而造成元件操作特性的擾動，本研究結果顯示MILC製程採用RTA技術，在生產製造奈米線通道之薄膜電晶體，元件特性的均勻性優於一般採用爐管製備法。

In this thesis, low-temperature poly silicon (LTPS) technique is employed to fabricate TFTs with poly-Si nanowire (NW) channels. Rapid thermal annealing (RTA) not only possesses a good selective heating function with specific materials, but the process time and the issue of thermal budget can be diminished, even re-crystallization rate of a-Si is increased during metal-induced lateral crystallization (MILC) process. However, the mechanism of solid phase crystallization (SPC) takes place earlier in the film as the crystallization temperature increases; the laterally-grown cryststalline grain of MILC is blocked. By adjusting RTA temperature and annealing time, the impacts on the performance of the fabricated NW-TFTs are discussed. The effects of seeding window arrangement and different crystallization strategy are investigated as well via material analysis, electrical characteristics, and extraction of activation energies. Moreover, there exists crystalline variation among the poly-Si NWs. Therefore, the fluctuation of NW-TFT performance is observed. In this regard, our results indicate that MILC process with pulsed RTA (PRTA) technique achieves better uniformity in device characteristics than furnace anneal.