This paper presents the investigation of low‐temperatureinsitusurface cleaning of oxide‐patterned wafers by an Ar/H2plasma prior to the epitaxial growth on exposed silicon windows. Ar/H2plasma 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 theinsitusurface cleaning by ultralow‐pressure chemical vapor deposition from SiH4/H2in a high‐vacuum system (base pressure, 10−7Torr). 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 preepitaxialinsituAr/H2plasma sputter cleaning.