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題名 | 鉭基氮化物擴散阻礙層在銅金屬化系統之失效機制=Failure Mechanisms of Tantalum-based Nitride Diffusion Barriers Used in Copper Metallization |
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作者 | 許振聲; 陳錦山; | 書刊名 | 真空科技 |
卷期 | 12:2 1999.07[民88.07] |
頁次 | 頁5-17 |
分類號 | 440.39 |
關鍵詞 | 鉭基氮化物擴散阻礙層; 銅金屬化系統; 失效機制; |
語文 | 中文(Chinese) |
中文摘要 | 本研究主要探討厚度為40nm之不同氮含量之非晶質Ta N (a-Ta N)薄膜在銅金 屬化系統的高溫擴散阻礙行為與失效機制。綜合片電阻量測、X光繞射分析、穿透式電子顯 微繞射分析及掃瞄式電子顯微影像與X光映射分析結果發現:「Si/a-Ta N/Cu」金屬化系統 會隨溫度升高(450至900 ℃)依序產生銅晶粒成長、a-Ta N結晶轉變、巨大(尺寸1至40μm)Cu Si四角錐粒子析山與TaSi 析出的行為。銅會沿著結晶化Ta N薄膜的晶界或熱應力誘發 裂縫擴散進入矽晶終而造成四角錐Cu Si粒子之析出:銅膜會在Ta N的局部缺陷位置(晶 界或裂縫)產生破裂而聚集成小丘狀突起物,最後導致Cu原子沿這些局部缺陷穿越Ta N, 到達(100)矽晶之介面,繼而沿著不同的結晶方位逐漸消耗Si,終而形成被{111}四組平面所 包圍的Cu Si四角錐析出物。更高的溫度會導致Ta N的裂解,並與Si產生TaSi 化 合物。然而,氮含量較高之a-Ta N (a-Ta N )的結晶轉變(600 ℃)遠高於計量比Ta N (450 ℃),因此氮過度填充a-Ta2N試片具有明顯改進之擴散阻礙性能(Ta N 與Ta N 試片開 始破壞之溫度分別為500和600℃)。雙層a-Ta N (20 nm Ta N /20 nm Ta N )阻礙層設 計能大幅提高其結晶轉變溫度,而使其在更高的溫度(約625℃)仍然以非晶質的狀態開始破 壞。 |
英文摘要 | The feasibility of using 40-nm-thick amorphous Ta N(a-Ta N)thin films having different amounts of nitrogen as diffusion barriers for copper metallization has been evaluated. Results based on x-ray diffraction analyses, sheet resistance measurements, cross-sectional transmission and scanning electron microscopies consistently show that all the a-Ta N barrier layers degrade in a similar manner, initiated mainly by a complete crystallization of the amorphous barrier layers as the samples' temperature exceeds 450 ℃. This is followed by a diffusion of copper along grain boundaries and thermal-induced crevices of the crystallized Ta N thin films into the [100]-oriented silicon wafers, ultimately forming {111}-bounded pyramidal Cu Siprecipitates of sizes ranging from 1 to 40 μm. Prolonged heating at elevated temperatures greater than 650 ℃ causes Ta Nto dissociate, ultimately forming Ta Si . As adequately doping nitrogen into stoichiometric a-Ta N can substantially increase the crystallization temperature by approximately 150 ℃, the effectiveness of the nitrogen over-incorporated a-Ta N barrier layers can be markedly strengthened, subsequently elevating the degradation temperature by at least 100 ℃. |
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