高/低摻雜濃度矽晶於N2O氣體的熱氧化及元件應用

Abstract

次微米MOS元件需要高品質的超薄氧化層,最近藉著矽基板在N2O中的熱氧 化去成長超薄的閘極介電層,已引起廣泛的注意,但是現在對於在N2O中氧 化層的成長是否自我設限而未有明確的定論,這裡我們提出廣泛的結果而 證明出,高或低摻雜濃度矽晶的熱氧化並不會自我設限,在N2O的氧化我們 也發現了一些有趣的現象, 像氧化在高摻雜矽晶的增進及 (111) 和 (110) 矽晶氧化的氧化層厚度的交會效應.另外我們用N2O的氧化去研究以 沈積TEOS作為閘極氧化層的元件電性,結果顯示以N2O作退火處理的TEOS氧 化層,在經過通道熱載子強度試驗中,有較小的起始汲極電流衰退,而且和 熱氧化閘極氧化層比較,電導的衰退也只是差一點而已. High quality ultrathin oxide is requireed for deep submicron MOS devices. Recently, a new technique to grow thin thin gate dielectrics by oxidizing silicon substrates in pure N2O has been gaining wide attentions. However, there is an uncertainly whether the growth of Si in N2O ambient is self-limiting.In this study,we present extensive results of thermal oxidation of lightly and heavily doped silicon in N2O, and demonstrate that the thermal oxidation of silicon in pure N2O is not self- llmiting.The interesting phenomena of silicon enhanced oxidation on heavily doped substrates and oxide thickness crossover of (110) and (111) in the initial stage of oxidation have also been observed in N2O oxidation. The devices application utilizing N2O oxidation was used to study the electrical characteristics of MOSFET's with TEOS deposited gate oxides. Results show that devices of TEOS oxide with N2O anneal have smaller drain current degradation under CHC stress condition. The transconductance degradation is slightly worse as compared to thermal gate oxide devices.