由薄複晶矽經熱氧化或熱氮化所製備之穿隧氧化層

Abstract

在本論文中,我們提出了一種疊型結構以製備一具有非常高的電流注入效 率之穿隧氧化層. 這種穿隧氧化層其製程乃是藉矽基板上之薄複晶矽經熱 氧化或熱氮化/ 再氧化所製成. 當基板為高濃度摻雜時, 傳導10mA/ cm^2 之電流通過此種氧化層所需電場可從一般氧化層之10.2MV/cm降至約 5MV/ cm左右. 除了上述之優越的電流注入效率外, 此種氧化層的其他優點還包 括非常高的崩潰電場, 以及大的崩潰電場, 以及大的崩潰電荷(>100C /cm^2). 同時也顯示了疊型非晶矽之厚度應尋求其最佳值以達到良好的電 特性, 並且其界面陷阱密度及均勻性幾乎與普通的氧化層一樣. 此外, 這 種穿隧氧化層之可靠度比起一般的氮氧化層亦有明顯的改善. 也就是說, 若與氮氧化層比較, 此種穿隧氧化層在電性應力作用下會顯示出較低的界 面陷阱產生率和電荷捕捉率. In this thesis, we have proposed a stacked structure to prepare a tunnel oxide with a very high current injection efficiency. The process to prepare this kind of tunnel oxide is by use of thermal oxidation or reoxidation/nitridation of a thin polysilicon film on Si substrate. The electric field for conduction 10mA/cm^2 through this kind of tunnel oxide can be reduced from 10.2MV/cm for normal oxide to about 5MV/cm as the Si substrate being heavily-doped. Aside from the superior current injection efficiency, the other advantages of the optimum condition of this kind of tunnel oxide include a very high breakdown field, and a large charge to breakdown (>100Coul/ cm^2). It is also presented that the thickness of stacked a-Si film should be optimized to achieve excellent characteristics. Moreover, the interface trap density and uniformity are almost as good as those of normal oxide. In addition, the realiability of this tunnel oxide is siginificantly improved in comparison to the normal oxynitride, i.e., this tunnel oxide exhibits a less interface trap generation rate and a less charge trapping rate than those of normal oxynitride under electrical stress.