超低電阻率單晶二矽化鎳之可靠度量測

Reliability and Ultra-low Resistivity of Epitaxial Nickel Silicide for Future CMOS Source/Drain Contact

鄧旭昇(Hsu-Shen Teng)

指導教授 ： 辛正倫

國立中央大學/資訊電機學院/電機工程學系/碩士(2014年)

摘要

近年來為了有效的降低接觸電阻(contact resistance)，提出使用表面平整的磊晶金屬矽化物源/汲極結構來取代金屬矽化物源/汲極。目前有研究指出，一般成長二矽化鎳需要700℃以上的高溫，但當金屬Ni厚度小於某一臨界厚度時，即可在低溫下與矽反應成磊晶的二矽化鎳且不需要經過其他中間相(Ni2Si、NiSi)。本論文利用離子濺鍍機(Sputter)鍍膜後將Ni濕蝕刻掉，Ni會與矽形成一層超薄的鎳矽混合層，此層厚度約會小於能形成磊晶二矽化鎳所需的臨界厚度，因此再經過快速熱退火(RTA)處理後，即可在低溫下形成磊晶二矽化鎳。本論文將會在大電流密度下量測磊晶二矽化鎳與多晶二矽化鎳的可靠度(reliability)，並求出個別的活化能(activation；Ea)及電流加速因子(current acceleration factor；n)。最後利用公式來回推在正常電流密度使用下，磊晶二矽化鎳的元件失效時間。也將用四點量測機台、掃描式電子顯微鏡與穿透式電子顯微鏡，來研究磊晶二矽化鎳的電性、磊晶品質、表面型態及分析造成元件失效的原因。

關鍵字

單晶 ； 二矽化鎳 ； 可靠度 ； 電致遷移

並列摘要

Ultra-thin epitaxial NiSi2 was formed and the structure was examined by electronic microscopy techniques. Compared to previous reports, the resistivity of the epitaxial NiSi2 was unprecedentedly as low as 6 μΩ-cm. The reliability, which was investigated under different temperatures and current densities to understand its electronic characteristics, is 1.5 times longer than that of the conventional poly-crystalline counterpart. By using Black’s equation and measured the mean-time-to-failure values to obtain the reliability characteristics, the details of epitaxial and poly-NiSi2 were revealed. The electromigration phenomenon was obtained as the failure mechanism. This observation provides evidence that the epitaxial NiSi2 is promising as source/drain contact in the future.

參考文獻

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