Electrical Evaluation of Ru-W(-N), Ru-Ta(-N) and Ru-Mn films as Cu diffusion barriers

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• 作者：H. Wojcik^a ; ^{henry.wojcik@tu-dresden.de} ; R. Kaltofen^b ; U. Merkel^a ; C. Krien^b ; S. Strehle^a ; J. Gluch^b ; M. Knaut^a ; C. Wenzel^a ; A. Preusse^c ; J.W. Bartha^a ; M. Geidel^a ; B. Adolphi^a ; V. Neumann^a ; R. Liske^d ; F. Munnik^e
• 关键词：Cu diffusion barrier ; Ru composites ; Bias temperature stress ; Triangular voltage sweep
• 刊名：Microelectronic Engineering
• 出版年：2012
• 期刊代码：91_01679317
• 类别：cp
• 出版时间：April, 2012
• 卷：92
• 期：Complete
• 页码：71-75
• 文件大小：631 K

摘要

Co-sputtered Ru-Ta(N), Ru-W(N) and Ru-Mn composites are investigated in terms of their barrier properties against Cu diffusion. A wide range of stoichiometries is analyzed with regard to crystallization, barrier properties, resistivity, Cu adhesion and direct Cu plating behaviour. All films were annealed at 350 掳C and 600 掳C in forming gas for 1h and subsequently stressed at elevated temperatures and electrical fields (BTS, 250 掳C, 2 MV/cm, 30 min). The leakage current was monitored during BTS to observe increased leakage due to Cu diffusion. The Cu ions that eventually have passed the barrier and drifted into the dielectric of the MIS test structure were detected and quantified using the triangular voltage sweep method. The addition of 10%W or Ta into a Ru film already leads to a highly improved barrier performance against Cu diffusion, comparable to TaN, as long as the temperatures involved are kept below 350 掳C. Outstanding barriers were identified after 600 掳C annealing and subsequent BTS, among them Ru₅₀W_50, Ru₅₀Ta₅₀ and Ru₉₅Mn₅. However, only Ru₉₀Ta₁₀ and Ru₉₅Mn₅ offer an excellent Cu adhesion and the possibility of direct Cu plating.