探討晶片表面潔淨與閘極結構對閘極氧化層之影響

Abstract

對於電晶體而言，閘極氧化層的好壞是很重要的關鍵。在本論文中， 將探討晶片的表面潔淨與閘極結構對電晶體的閘極氧化層之影響。在第二 章中，我們對傳統式的RCA清洗晶片法作一些改良，在其第一步驟中加入 一種叫TMHA的特別藥劑，並將其第二步驟加以省去。將新方法所做的電容 元件與傳統清潔法比較，發現改良式清洗晶片法能大幅的改善MOS電容的 電特性。在第三章裡，我們對閘極層結構對閘極氧化層的影響作一個探討 。比較四種不同的閘極結構，包括多晶矽、非晶矽、長時間退火處理過之 非晶矽和氮化過之堆疊多晶矽(Stacked poly)。經過一連串的電性試驗比 較後，我們發現用氮化過的堆疊多晶矽作為閘極有最好的電特性。它具有 較大的崩潰電場和崩潰電荷、較低的電子捕捉率，並且在經過後段長時間 的高溫處理下仍然能有很好的電特性，這是其它三種結構所無法辦到的特 性。 The quality of gate oxide is the very important key point for MOSFET. Inthis thesis,the effects of the wafer surface clean and gate structure on gate oxide will be studied. In chapter 2,we improved the traditional RCAinitial clean method. One chemical solution named TMHA had been added intoRCA standard cleaning one,and RCA standard cleaning two had been omitted. The MOS capacitor using traditional RCA initial clean method. Wefound that new clean way could improve the MOS capacitor in electrical characteristics very well. In the chapter 3,we studied on the effects of gate structure for gate oxide. Choosing four types of gate structure to compare. They includedpolysilicon,amorphous,annealed amorphous and nitrided stacked polysilicon.After one series of electrical tests, we found that the MOS capacitor with nitrided stacked polysilicon gate had the best electrical characteristics. It had higher dielectric breakdown field, higher charge-to-breakdown andlower electron trapping rate. It could also have the very good performanceafter long-time annealing at high temperature. However, the othe gate structures colud not approach its performance.