Surface passivation by adding fluorocarbons and chlorofluorocarbons into an Al dry etch reactor

Abstract

Adding fluorocarbon or chlorofluorocarbon compounds into an Al etch reactor can alter the induction time, change the Al etch rate, and inhibit the Al etching from the grounded electrode and chamber wall. These phenomena are explained by a surface passivation mechanism. During an etching process, the aluminum can react with chlorine-containing radicals and fluorine-containing radicals simultaneously to form either a volatile aluminum chloride or a stable passivation layer. The important parameters which control the etch and passivation rates, for a given system geometry, are the gas flow rate, the fluorine atomic concentration, and the bias voltage of the bottom electrode.