Effect of Via Etch Profile and Barrier Metal on Electromigration Performance of W-Filled Via Structure in TiN/AlCu/TiN Metallization

Abstract

AbstractIn this study, we have evaluated electromigration performance of W-plug vias, fabricated with process variations in via hole etching as well as in via barrier deposition, on a TiN(barrier)/AlCu/TiN metallization system. We found that via etch profile scheme as well as deposition conformity for via barrier can significantly affect W-plug via lifetimes. The results indicate that the quality of contact with AlCu layer of bottom level metal is a critical factor in determining via lifetime. Precise control of via etching or by use of conformal via barrier to ensure a good barrier between W-plug and the AlCu of bottom level metal is essential for achieving reliable via structures.