高效能雙通道鎳金屬誘發低溫複晶矽薄膜電晶體之製備方式及特性分析

Abstract

在本研究中，主要利用鎳金屬誘發側向結晶(Nickel-Induced Lateral Crystallization , NILC)之成長機制並結合高效能雙通道(double channel, DC)結構製作出電性特性較佳之低溫複晶矽薄膜電晶體(Low-Temperature Polycrystalline Silicon Thin Film Transistor , LTPS TFT)，文中探討NILC與此新式結構分別對其電性之改善效益的成因。此新式之結構中使用雙通道結構，如此可結合了場引效汲極(Field Induced Drain, FID)及抬升式汲源極(Raised Source/Drain, RSD)之設計，可降低通道間電場，使得臨界電壓下降、提昇載子遷移率、減少扭結效應(kink effect)及降低次臨界擺幅。而NILC法因晶界內懸鍵之深態位少、累積之正電荷及施體型缺陷等原因貢獻，而獲得較高之載子遷移率、低次臨界擺幅及較小之臨界電壓。首先，本研究中先就單通道及雙通道低溫複晶矽薄膜電晶體之電性表現做討論，得知雙通道元件其電性改善成效高於單通道元件。再進一步，就NILC法及固相結晶法(Solid Phase Crystallization , SPC)之雙通道薄膜電晶體元件進行討論，NILC因晶粒大等因素，有較佳之電性表現。綜合探討機制及結果分析，結合NILC法、FID及RSD結構之雙通道鎳金屬誘發低溫複晶矽薄膜電晶體，電性上得到了卓越的改善，例如：包含降減少界電壓、提昇載子遷移率、降低扭結效應及減小之次臨界擺幅等，驗證了實驗設計。

In this research, we mainly discuss methods to produce a Low-Temperature Polycrystalline Silicon Thin Film Transistor(LTPS TFT) with better electric properties by using Nickel-Induced Lateral Crystallization ( NILC) and the construction of double channel. We also discuss factors that improve NILC’s electric properties and its new construction. The design of using double-channel in the new construction, which enables the combination of Field Induced Drain (FID) and Raised Source/Drain (RSD) should provide below three benefits: 1. Reduce the electric field to lower the threshold voltage, 2. promote the carrier mobility, 3. decrease the kink effect, and reduce the subthreshold swing. Moreover, due to the less deep state of dangling bonds, the accumulation of positive charge, and donor-like defect, NILC gains higher mobility and subthreshold swing and smaller threshold voltage. At first, the paper will discuss the performances of electric properties with single channel and double channel. Secondly, our experiment proved that the component of double channel improved electric properties better than the component of single channel. Finally, we compared the TFT elements of NILC method and SPC method. As the result, we found out that NILC gained better electric properties due to the larger grain size, and so on. By combining the new findings from the results, we claim that the Double Channels LTPS NILC TFTs with the combination of NILC method, FID, and the construction of RSD will improve electric properties greatly, such as, lowering the voltage, promoting the carrier mobility, reducing kink effect, and minimizing the subthreshold swing; which proved the design of the experiment to be true and accurate.