Separation by Bonding Si Islands (SBSI) for Advanced CMOS LSIs - A Study on Selective Etching of SiGe Layers for SBSI Process

摘要

The etching selectivity of SiGe against Si and the surface roughness after selective etching of the SiGe layer were investigated in samples with SiGe/i-Si(non-doped-Si) stacked layers. It was found that the etching of the i-Si layer could be reduced by decreasing the HNO{sub}3 concentration; thus, the etching selectivity of SiGe against Si improved by decreasing the HNO{sub}3 concentration. The surface roughness also improved as HNO{sub}3 decreased. Furthermore, the thickness of the Si island fabricated by the SBSI process became uniform by decreasing the HNO{sub}3 concentration.