MOS fabrication process integrating self-aligned polysilicon gate and post-processed metal gate devices on a single die

A microelectronic process allowing successful fabrication of polysilicon gate and replacement metal gate devices on the same die is described. The characteristics of aluminium replaced gate devices are compared to those of coexistent polysilicon gate devices showing agreement with theoretical predictions. Following standard processing, plasma back-etching steps are used to form the replacement gates. Virtually any material which can be deposited and patterned on silicon dioxide can be used as the replacement gate material