Research and optimization of plasma-enhanced chemical vapor deposition α-Si process compatible with 8-in. CMOS technology

This research focuses on the optimization of PECVD-deposited α-Si in the fabrication of metasilicon lenses compatible with 8-in. CMOS semiconductor processes. Using SiH4 as the precursor gas, the study addresses the bubble formation issue in α-Si films during subsequent PECVD steps by optimizing process parameters and introducing an additional annealing step. Experimental results show that the refractive index, extinction coefficient, and deposition rate of the α-Si film are influenced by RF power, spacing, SiH4 flow, and chamber pressure. After annealing, both the refractive index and extinction coefficient increase with longer annealing duration. The introduction of an annealing step in the CMOS process effectively releases free hydrogen from the α-Si film, thus preventing bubble formation. The findings of this study provide valuable insights into optimizing PECVD α-Si film deposition, contributing to advancements in related technologies.