- 學位論文
反應性濺鍍製備Ta-Co-N三元合金薄膜與銅金屬化製程整合特性探討
Evaluation of Ternary Alloy TaCoN Thin Films Deposited by Reactive Sputtering for Copper Metallization
摘要
本研究是以不同比例的TaCo靶材在不同的N2流量下，於Si基板上濺鍍TaCoN三元合金薄膜做為Cu製程之擴散阻礙層。將Si/barrier/Cu結構在RTA中做500-900oC熱處理後，利用四點探針(FPP)、X光繞射分析儀(XRD)、掃描式電子顯微鏡(SEM)、歐傑電子能譜儀(AES)及穿透式電子顯微鏡(TEM)分析薄膜之電性、相變化、表面形態與元素之縱深分佈及微結構。 實驗結果顯示，TaCoN三元合金薄膜初鍍膜為非晶質結構，各組實驗中最低的電阻率為183.5 μΩ-cm，薄膜電阻率隨N2含量增加而增加，Co原子百分比含量較高的薄膜有較佳的導電性，結晶溫度在N2流量高於1 sccm時反而下降。與Cu製程整合後發現， N2流量為1 sccm之Si/TaCoN/Cu結構具有最佳的熱穩定性，失效溫度可達750oC。失效機制除因Cu與Si反應形成Cu3Si結晶相，另外Cu在表面產生聚集也會使得薄膜電阻變化率升高，導致Si/TaCoN/Cu結構失效。 本實驗中因N2含量的增加使得N2原子與Co產生反應的機會增加而導致低溫時CoN結晶相的產生，非晶質薄膜結晶化所產生的晶界因而提供Cu原子的擴散路徑，此結果不利於Cu製程的整合。因此一味的提高TaCoN薄膜的含N2量除了使得導電率下降之外，也造成結晶溫度的降低，並且降低Si/TaCoN/Cu結構的失效溫度。
關鍵字
無資料並列摘要
Thin-film properties and diffusion barrier characteristics of TaCoN films on silicon substrate prepared by a dc reactive magnetron sputtering at different nitrogen partial pressures are investigated. This work examines the sputtering nitrogen partial pressure impact on thermal stability, crystal structure, surface morphology and electrical properties of the films using x-ray diffractometry, electron microscopy and four-point probe measurement after rapid thermal annealing the deposited films at an elevated temperature. The findings indicate that the as-deposited TaCoN films exhibit an amorphous structure. The lowest electrical resistivity is 183.5 μΩ-cm for TaCo (77.8:22.2) films. The Si/TaCoN (1 sccm)/Cu exhibits a better thermal stability up to an annealing temperature of 750oC. The increasing in nitrogen partial pressure during deposition enhances the reaction between cobalt and nitrogen by forming CoN phase at a relative low temperature. The increase in nitrogen partial pressure during sputtering induces a lower conductivity and a lower crystallization temperature of the films, and therefore reduces the failure temperature on copper metallization.