ELECTROLESS PLATING OF COBALT ALLOY THIN FILMS AS ESSENTIAL THCHNOLOGY FOR COPPER INTERCONNECT RELIABILITY IMPROVEMENT

摘要

Electroless plated CoWP films were investigated as a capping layer to improve the reliability of Cu interconnects. The thin films were successfully formed on 200mm and 300mm wafers using an automated single-wafer tool. The thin film deposited on both Cu blanket and patterned wafers showed satisfactory thickness controllability and uniformity. The thickness of continuous films deposited can be controlled as thin as 5nm. The metallic contamination on the wafer's backside was kept at an acceptable level for production. The film was proven to be a diffusion barrier against Cu and oxygen at thickness as thin as 20nm. Smooth morphology and high selectivity of deposition was also obtained. The electrical performance of 250nm interconnects on wafers were measured, and high comb yield of current leakage and line resistance increase less than 2% were confirmed.