為了改善MOSFET電晶體的性能，元件的尺寸被要求越來越小，許多新穎的研究成果已被發表出來，其中，高功函數金屬閘極的研究相當引人注目。
本論文研究的重點放在高功函數金屬閘極和cap layer 金屬的材料選擇上。第一部份為研究WHfxN(WHf_H)和TiN/WHfxN(TWHf_H)，運用在high-k介電層材料 HfAlO。根據學長的研究結果，單層WHf_H的電特性極佳。沉積cap layer TiN主要的想法是，它能阻擋外界的氧原子進入而向下擴散，並保留單層WHf_H的電特性。由實驗結果發現，TWHf_H 因為有cap layer TiN的作用，在經過高溫退火之後，雖然抑制了氧原子的擴散，使得EOT和Jg的熱穩定性較好。但在可靠性上的表現則較差。功函數方面，兩種結構功函數在PMA900oC下仍有5.02 eV以上，相當適合於pMOS元件的應用。
第二部分為探討堆疊金屬閘極TiN/WN (TW_H)和TiN/WHfxN(TWHf_H )，並運用在high-k介電層材料 HfAlO。摻雜Hf主要的想法是，期望能改善金屬閘極和閘介電層之間的介面品質。由實驗結果發現，TWHf_H在經過高溫退火之後，在多項電特性都獲得改善。在功函數的熱穩定性上，摻雜Hf使得結晶更完美，功函數也較好，適合於pMOS元件的應用。
第三部分探討堆疊金屬閘極TiN/WN(TW_H)和TaTixN/WN(TaTiW_H)，並運用在high-k介電層材料 HfAlO。延續第一部分，由於TW_H在經過高溫退火之後，Ti擴散較為嚴重，所以在TiN摻雜Ta，期望能抑制Ti擴散。由實驗結果發現，TaTiW_H閘極在經過高溫退火之後，氧原子和金屬離子的擴散並不明顯，故其熱穩定性和可靠度都獲得改善。功函數方面，TaTiW_H 高功函數結晶更明顯，功函數較大，適合於pMOS元件的應用。

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