以化學氣相方式與濺鍍方式沉積氮化鉬擴散障礙層在極大型積體電路金屬化應用上之研究

Abstract

在本論文中,我們利用一種新的有機金屬前驅物BDBTM(bisdiethylamido bistertbutylimido molybdenum) 以化學氣相方式沉積成長氮化鉬,用作 銅與鋁金屬導線的擴散障礙層. 在物性方面,我們提出在低溫下成長的氮 化鉬再加上氨氣退火處理以及在低溫下成長氮化鉬並加上在高溫下對氮化 鉬薄膜做氮氣電漿處理二種方式,以得到高均覆性低阻值的氮化鉬薄膜.在 電性方面,利用金屬/障礙層/二極體結構在歷經退火處理後的漏電程度來 測定此障礙層的熱穩定性. 60奈米厚的薄膜對銅的熱穩定性可達攝氏500 度, 20奈米厚的薄膜對銅和鋁的熱穩定度分別達到攝式450度和500度退 火.在以濺鍍沉積氮化鉬(MoN)與氮-矽-鉬(MOSiN)化合物的研究中,我們探 討在各種不同的氮含量下,薄膜的物何和電性對於退火處理後的熱穩定性 之影響,並成功地找出最佳化的沉積條件. 在最佳條件下,60奈米厚的氮化 鉬對銅的熱穩定度可達攝氏650度,而摻入矽原子的氮化鉬在最佳條件下, 對銅的熱穩定度更可高達攝氏750度. 原因是矽原子的摻入,增加了氮化鉬 的結晶溫度(crystallization temperature),因此降低了銅在晶界(grain boundary)的擴散. In this thesis, we investigated the physical and electrical properties of the metalorganic chemical vapor deposition of MoN thin film. Molybdenum nitride was deposited using a new precusor bisdiethylamido bistertbutylimido molybdenum by thermal decomposition. To lower the film resistivity, CVD MoNx film deposited at 450oC with in-situ ammonia post treatment at 650oC/30min was used. In addition, CVD MoNx film deposited at 450oC with a sequential in-situ nitrogen plasma treatment at 650oC/30min for every 10 nm film was performed to obtain high conformity and low resistivity barrier films. The leakage current measurement on the metal/barrier/p+n junction diodes was used to characterize the thermal stability. A 60nm CVD MoNx film was able to prevent Cu diffusion at temperature up to 500oC for 30 min. A 20 nm CVD MoNx film was able to prevent Cu and Al diffusion at temperature up to 450oC/30min and 500oC/30min annealing, respectively. In the study of PVD MoN and PVD MoSiN of various nitrogen contents, we obtained the optimal Ar/N2 ratio during sputtering. Under the optimal conditions(Ar/ N2=12/3), the 60 nm PVD MoN film was able to prevent Cu diffusion up to 650oC for 30 min, while the 60 nm PVD MoSiN film has an evenhigher thermal stability of 750oC. This is attributed to the increase in crystallization temperature by the silicon incorporation in the MoN film.Higher crystallization temperature has reduced the grain boundary diffusion of copper.