5.1 結論
對於高介電常數閘極電晶體在負偏壓溫度不穩定性的研究，可分 為界面層選用二氧化矽或氮氧化矽的影響，高介電常數材料選用氧化 鉿或氮氧矽化鉿的影響，閘極材料為金屬氮化鈦或多晶矽的影響以及 驗證負偏壓溫度不穩定性的主導退化機制是高介電常數薄膜裡的陷 阱。
關於界面層的選用二氧化矽的元件比使用氮氧化矽元件具有較 低的界面陷阱電荷、較薄的等效氧化層電荷，但其受到負偏壓溫度不 穩定性的劣化較為嚴重。而選用氮氧化矽元件比使用二氧化矽有較低 的閘極漏電流，較高的漂移率及較小的負偏壓溫度不穩定性影響。
關於高介電常數材料選用氮氧矽化鉿的元件比使用氧化鉿的元 件具有較大的飽和電流，較低的界面陷阱數量以及較高的漂移率。對 於選用氧化鉿的元件比使用氮氧矽化鉿的元件具有較低的閘極漏電 流以及較小的等效氧化層厚度。另外在負偏壓溫度不穩定性方面，使 用氮氧矽化鉿的元件比具有一層氮化矽覆蓋於氧化鉿上面的元件有 較大的劣化程度。
對於驗證P型高介電常數之場效應電晶體其負偏壓溫度不穩定性
的行為中，主導退化機制的是高介電常數薄膜裡的陷阱。利用多晶矽 閘極堆疊元件為氮氧矽化鉿搭配二氧化矽其顯示當強迫電壓值比 -2.5+VTH伏特還大時，被陷入在薄膜的電荷以電洞為多數，而當強迫 電壓比-2.5+VTH伏特還小時，被陷入在薄膜的電荷以電子為多數。故 高介電常數閘極電晶體在負偏壓溫度不穩定性受本體缺陷影響，使得 有異於以往的負偏壓溫度不穩定性現象發生。
關於高介電常數材料選用金屬閘極高介電常數介電層元件比多 晶矽閘極高介電常數介電層元件的使用上有更低的等效氧化層厚 度，較高的漂移率，較佳的次臨界斜率，較好的閘極控制能力，以及 較高的驅動電流。在負偏壓溫度不穩定性方面造成兩種元件的特性退 化有不同現象，以臨界電壓改變量方面來看使用金屬閘極高介電常數 介電層元件有較少的負偏壓溫度不穩定性現象。
5.2 未來展望
本文研究高介電常數閘極電晶體在負偏壓溫度不穩定性實驗中 溫度的設定都為室溫。雖然元件施加負閘極電壓或者在高溫操作，其 一即可造成負偏壓溫度不穩定性的現象，但同時考慮兩者時將使負偏 壓溫度不穩定性現象更貼近元件或產品在使用時的狀況。所以此研究
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