MODEL FOR AL ETCH-RATE ENHANCEMENT AT LOW-TEMPERATURES

A surface reaction model for aluminum etching by chlorine is proposed, which takes into account the temperature dependence of the thermal pr ocesses and the ion-assisted processes simultaneously. In the model, c hlorine physisorption and chemisorption are treated separately, based on the previous work on chlorine adsorption on aluminum. In particular , cluster formation was introduced into the chlorine physisorption pro cess to allow physisorbed species to exist on the Al surface. The mode l reproduced the measured Al etch rate, including the Al etch-rate enh ancement in the low-temperature regime. This etch-rate enhancement was found to be brought about by the increase in physisorbed chlorine on the Al surface, followed by ion-assisted reaction and desorption.