As the nanotechnology gate is scaling down, the fabrication technology of gate spacer for CMOS transistor becomes more critical in manufacturing processes. For CMOS technologies, sidewall spacers play an important role in the control of short channel effects by offsetting ion implantation profiles from the edge of the gate. A sidewall spacer patterning technology yields critical dimension variations of minimum-sized features much smaller than that achieved by optical Complementary Metal–Oxide–Semiconductor (CMOS) fabrication processes integration. The present study is to overcome the fabrication limitations and more particularly focus on etching processes integration on structural and formation processing for complementary metal oxide semiconductor nanofabrication process on gate spacer technology and electrical characteristics performance of nanotechnology gate structure were included. Based on the investigation of the etching effect and interface film variation on the electrical characteristics of the gate oxide on etching profile and their impacts on the sidewall transistor gate structure, a novel etching integration process for optimal controlled sidewall gate spacer fabrication was developed.