Low-temperature in situ surface cleaning of oxide-patterned wafers by Ar/H2 plasma sputter

Abstract

This paper presents the investigation of low-temperature in situ surface cleaning of oxide-patterned wafers by an Ar/H2 plasma prior to the epitaxial growth on exposed silicon windows. Ar/H2 plasma sputter cleaning was carried out at 2.5 or 20-W rf power and a susceptor dc bias from 100 down to 0 V. Epitaxial layers were grown immediately after the in situ surface cleaning by ultralow-pressure chemical vapor deposition from SiH 4/H2 in a high-vacuum system (base pressure, 10 -7 Torr). Process temperatures were varied from 800 down to 500°C. The epitaxial films were characterized by cross-sectional transmission electron microscopy, secondary-ion-mass spectroscopy, Nomarski optical microscopy, and ion channeling Rutherford backscattering spectroscopy. It was found that a highly structural epitaxial layer can be grown down to 600°C and an epitaxial layer can be grown at 500°C by utilizing the preepitaxial in situ Ar/H2 plasma sputter cleaning.