高介電常數材料氧化鋁在矽基板上之介面特性研究

Abstract

在眾多高介電係數材料之中，氧化鋁是一種非常有潛力的高介電係數材料。它有較高的介電係數（約8∼10），足夠高的載子能障（對電子約2.9電子伏特，對電洞約4.3電子伏特），以及與矽有著良好的熱穩定性。在論文中，我們研究氧化鋁經由NH3 表面處理與在氧氣與氮氣環境下進行沈積後退火（ＰＤＡ）在物性，電性，及可靠度分析。沈積後退火（ＰＤＡ）可以有效的降低表面粗糙度。我們發現NH3 表面處理與沈積後退火（ＰＤＡ）都能改善試片在電容-電壓電性分析上的平台現象，其中氨氣表面處理更可以降低試片的漏電流。

有先經過NH3 表面處理與在氮氣環境下進行沈積後退火（ＰＤＡ）的話，其介電質的可靠度將會變得較佳。在氧化鋁薄膜內的漏電傳導機制是由Schottky發射所主導的。綜上所述，氧化鋁介電層的特性在NH3 表面處理配合後續沈積後退火處理後得到了有效的改善。這種新穎的NH3 表面處理與沈積後退火提供了未來奈米元件應用在金氧半沈積處理上一個極佳的選擇。

Aluminum oxide (Al2O3) is one of the potential high-k materials. It has the higher dielectric constant (8~10), higher barrier height ( 2.9eV for electrons , and 4.3eV for holes ), and excellent thermal stability. In the thesis, physical, electrical and reliability characteristics of Al2O3 film with NH3 surface treatment and Post Deposition Annealing (PDA) in the O2 and N2 ambient were studied. The PDA can effectively reduce surface roughness. The PDA and NH3 surface treatments both can improve the C-V curves. Moreover, the lower leakage current is observed in NH3 surface treatment samples.

The reliabilities can be improved by the NH3 surface treatment after PDA in a N2 ambient. The conduction mechanism in the Al2O3 thin film is dominated by the Schottky emission. To sum up, the characteristics of Al2O3 gate dielectrics with NH3 surface treatment and subsequent PDA treatment described above are effectively improved. This novel NH3 and PDA treatment provides an alternative for post metal-oxide deposition treatment in nanoscale device application.