A low-temperature and high-quality radical-assisted oxidation process utilizing a remote ultraviolet ozone source for high-performance SiGe/Si MOSFETs

Abstract

By utilizing a remote ultraviolet ozone source, a low-temperature (600–700 °C) radical-assisted oxidation (RAO) process to produce high-quality ultrathin (1.4–3.7 nm) gate oxides was successfully developed for the fabrication of high-performance SiGe/Si metal-oxide-semiconductor field effect transistors (MOSFETs). The oxide grown by this technique showed much improved leakage and breakdown properties, compared with that grown without ozone. The reactive oxygen species in the RAO process seemed to cure the unpaired bonds in oxide networks making them more robust and dense, without an increase in thermal budget. The Si0.8Ge0.2 p-channel MOSFET with a RAO gate oxide exhibited superior device and 1/f noise characteristics to that with a standard higher temperature furnace oxide. This was because of the suppressed Ge-related gate-oxide degradation at the reduced process temperature when the Si-cap layer was thinned to below 2 nm. These suggest that the RAO process is particularly suitable for SiGe/Si MOSFET devices requiring a high-quality and low-temperature oxidation process.