A quarter-micrometer interconnection technology using a TiN/Al-Si-Cu/TiN/Al-Si-Cu/TiN/Ti multilayer structure

An 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 DRAMs. It was found that intermetallic compounds such as TiAl/sub 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-enhanced 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.<
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