Removal of Titanium Oxide Grown on Titanium Nitride and Reduction of Via Contact Resistance Using a Modern Plasma Asher

In making multi-level interconnects, a via layer is generally made of a dielectric layer grown on a TiN/AlSiCu/TiN metal stack. The via contact hole to the lower level metal is first etched after metal patterning and intermetal oxide deposition, then the resist mask for via etch is stripped in an oxygen plasma at high temperature before filling the via with tungsten or aluminum. However, during the resist stripping process, the titanium nitride …