Advantages of silicon Key: ability to form on silicon a stable, controllable oxide film(silicon oxide, Sio2) that has excellent insulating properties Selective etching HF dissolves Sio, not si SiO2 shields Si from doping(photosensitive polymer films are used to define shielded regions)Advantages of Silicon Key: ability to form on silicon a stable, controllable oxide film (silicon oxide, SiO2 ) that has excellent insulating properties. • Selective etching: HF dissolves SiO2 not Si • SiO2 shields Si from doping (photosensitive polymer films are used to define shielded regions)