Integration of microwave-annealed oxidation on germanium metal-oxide-semiconductor devices

In this paper, a method that entails using microwave thermal oxidation to form a high-quality gate dielectric on Ge through surface passivation at considerably low temperatures (<400 °C) is presented. Formation of the GeO_x layer was confirmed by x-ray photoelectron spectroscopy. To reduce the bulk trap density and interface trap density (D_it), microwave thermal oxidation was employed for postdeposition microwave thermal oxidation after the deposition of Al₂O₃ through atomic layer deposition. Tiny frequency dispersion in capacitance measurement and a low D_it value of 5.9 × 10¹¹ cm⁻² eV⁻¹ near the midgap confirmed a desirable passivation effect, which was favorable in mitigating the formation of dangling bonds on the Ge surface. A small hysteresis in capacitance was also observed, suggesting that the bulk dielectric was of high quality. On the basis of these characteristics, microwave-activated GeO_x is a promising passivation layer material for aggressively scaled Ge-related metal oxide semiconductor devices.