Flexible Control of Si Etching and Si/SiGe Selectivity for Advanced 3D Integration

Si/SiGe etch selectivity was controlled through surface passivation, oxidation, and digital etching. NH₄OH showed high selectivity toward Si, further enhanced by (NH 4 ) 2 S-induced suppression of SiGe etching. H 2 O 2 -assisted surface oxidation enabled preservation of Si pattern integrity during the thinning process. In addition, by incorporating acidic environments and fine-tuned digital etching, Si/SiGe selectivity was modulated with increased flexibility. These approaches offer flexible etch control for advanced Si/SiGe integration.