The epitaxial silicon layer selectively grown on the reactive ion etched (RIE) silicon substrate using CF4, CHF3and Ar etching gases has been studied. Defects and contaminants induced by the RIE process result in a rough epilayer, and degrade the current–voltage (I–V) characteristics. An interfacial carbide layer is present between the epilayer and the RIE treated substrate. Using an efficient and convenient after‐etching treatment with a CF4/O2low‐energy plasma, we obtain a clean Si surface in the patterned oxide windows for selective epitaxial growth, and the electrical characteristics are significantly improved. ©1995 American Institute of Physics.