A QUARTER-MICROMETER INTERCONNECTION TECHNOLOGY USING A TIN/AL-SI-CU/TIN/AL-SI-CU/TIN/TI MULTILAYER STRUCTURE

A new interconnection structure using a TiN/Al-1%Si-0.5%Cu/TiN/Al-1%Si-0.5%Cu/TiN/Ti multilayer conductor was investigated as a quarter-micrometer interconnection candidate for 256-Mb DRAM's. It was found that intermetallic compounds such as TiAl(x) were formed at both grain boundaries of Al-Si-Cu and interfaces between Al-Si-Cu and TiN of the multilayer, resulting in both increase in Vickers hardness and suppression of stress relaxation. The multilayer conductor strip, which was covered with plasma-enchanced chemical vapor deposition silicon nitride (P-SiN), suppressed stress-induced voiding after heat treatment at 500-degrees-C. Electromigration tests for quarter-micrometer wide multilayer strips indicated the improvement in the mean time to failure and the increase of the standard deviation.