利用CVD TEOS 在二矽烷複晶矽和堆疊結構複晶矽薄膜上沈積氧化層之特性分析

Abstract

在本論文中，我們探討了利用CVD TEOS在二矽烷複晶矽和堆疊結構複晶矽薄膜上沈積複晶矽氧化層之特性，並使用N2O快速退火來改善其特性。我們藉由原子力顯微鏡(AFM)觀察到，利用二矽烷取代傳統的矽烷所沈積的複晶矽薄膜有較平坦的表面，因此，不管是利用PECVD TEOS或LPCVD TEOS，沈積在二矽烷複晶矽表面的複晶矽氧化層都有較佳的電特性，如較大的崩潰電場、較大的崩潰電荷密度及較低的電子補抓率。此外，我們提出以堆疊結構的複晶矽來當下層複晶矽（Poly-1），因為它使複晶矽氧化層與複晶矽界面較平坦，且使較少的磷和較多的氮進入複晶矽氧化層內，利用LPCVD TEOS在堆疊結構的複晶矽薄膜表面上沈積之複晶矽氧化層，經過N2O快速退火後，有高達55.4庫侖/平方公分的崩潰電荷密度。

In this thesis, we investigate the CVD TEOS polyoxides deposited on disilane polysilicon films and stacked polysilicon films with rapid thermal N2O (RTN2O) annealing. It is found that the smoother polysilicon/polyoxide interface can be obtained by replacing conventional silane polysilicon films with disilane polysilicon films. Therefore, both the PECVD TEOS and LPCVD TEOS polyoxides deposited on disilane polysilicon films exhibit higher dielectric breakdown field, lower leakage current and lager charge to breakdown (Qbd) than those deposited on silane polysilicon films. In addition, we present a stacked polysilicon film as bottom polysilicon film (poly-1) to improve polyoxide integrity due to that stacked sample has smoother polysilicon/polyoxide interface, less phosphorus in polyoxide and more nitrogen incorporation at polysilicon/polyoxide interface than non-stacked sample. The Qbd of the stacked sample with RTN2O annealing is as high as 55.4 C/cm^2 for a polyoxide of 130A thickness.