Application of plasma oxidation to strained-Si/SiGe MOSFET

We have applied microwave-plasma oxidation to the gate oxide formation of strained-Si metal-oxide-semiconductor field-effect-transistor (MOSFET). Change in surface morphology of plasma oxidized strained-Si/SiGe is studied using an atomic force microscope (AFM) and compared with thermal oxidation. The AFM observation is carried out before and after oxidation in an identical area of a single sample. Plasma oxidation at 400 ∘C which proceeds under diffusion-limited condition suppressed nonuniform oxide growth caused by cross-hatch related surface morphology and is able to form gate oxide on strained-Si/SiGe without increase in surface roughness. Strained-Si n-channel MOSFETs on 15%-Ge content wafer were fabricated and the transconductance was enhanced by 70% compared with unstrained Si devices.