A novel two-step etching to suppress the charging damages during metal etching employing helicon wave plasma

A two-step etching has been performed to eliminate the plasma charging damages during helicon-wave plasma metal etching without selectivity loss. This technique utilized a normal etching recipe to remove the Al film followed by an optimized etching recipe for the overetching step. By increasing the bias power and decreasing the source power, the optimum etching recipe can target the plasma more directionally and reduce the Al charging damages. Eventually, the damage mechanism was also reported.