ELECTRON-CYCLOTRON-RESONANCE MICROWAVE PLASMA-ENHANCED SIGE OXIDATION AND MOS-TRANSISTORS

A new low temperature process using electron cyclotron resonance (ECR) microwave plasma has been developed to grow (not deposit) a stoichiometric SiGe oxide directly on Si1-xGex alloys. In situ x-ray photoelectron spectroscopy (XPS) measurements indicate that both Si and Ge are fully oxidized and Anger depth,profiling reveals that no Ge segregation occurs at the oxide/SiGe interface or near the oxide surface. The ECR-grown SiGe oxides have fixed oxide charge density 1x10(11) cm(-2) and interface trap density 1x10(11) cm(-2) eV(-1). The mean breakdown strength for the ECR oxide is 8-10 MV/cm. High quality 1 mu m Al-gate Si0.85Ge0.15 pMOSFETs with an ECR gate oxide have also been fabricated. It is found that saturation transconductance increases from 48 mS/mm (300 K) to 60 mS/mm (77 K), Low field hole channel mobility is measured at 300 K and 77 K. The best experimental values are about a factor of two better than the corresponding silicon devices.