During the etching process, the wafer surface temperature is an important parameter which influences the reaction probabilities of incident species, the vapor pressure of etch products, and the redeposition of reaction products on feature surfaces. In this study, the authors investigated that the effect of substrate temperature on the etch rate of Al2O3 thin film and selectivity of Al2O3 thin film over hard mask material (such as SiO2) thin film in inductively coupled plasma as functions of Cl-2 addition in BCl3/Ar plasma, rf power, and dc-bias voltage based on the substrate temperature in range of 10-80 degrees C. The elements existed on the surface were analyzed by energy dispersive x-ray and x-ray photoelectron spectroscopy.