High-quality HfSiON gate dielectric and its application in a gate-last NMOSFET fabrication

HfSiON gate dielectric with equivalent oxide thickness of 10Å was prepared by reactive sputtering. It exhibits good physical and electrical characteristics, including good thermal stability up to 900°C, high dielectric constant and low gate leakage current. It was integrated with TaN metal gate in a novel gate-last process flow to fabricate NMOSFET. In the process, poly-silicon was deposited on HfSiON gate dielectric as dummy gate and replaced by TaN metal gate after source/drain formation. Because of the metal gate formation after the ion-implant doping activation at high temperature, HfSiON/TaN NMOSFET with good driving ability and excellent sub-threshold characteristics was fabricated.