Plasma process for etching multicomponent alloys

Abstract

A method of etching a multicomponent alloy on a substrate, without forming etchant residue on the substrate, is described. In the method, the substrate is placed in a process chamber comprising a plasma generator and plasma electrodes. A process gas comprising a volumetric flow ratio V.sub.r of (i) a chlorine-containing gas capable of ionizing to form dissociated Cl.sup.+ plasma ions and non-dissociated Cl.sub.2.sup.+ plasma ions, and (ii) an inert gas capable of enhancing dissociation of the chlorine-containing gas, in introduced into the process chamber. The process gas is ionized to form plasma ions that energetically impinge on the substrate by (i) applying RF current at a first power level to the plasma generator, and (ii) applying RF current at a second power level to the plasma electrodes. The combination of (i) the volumetric flow ratio V.sub.r of the process gas and (ii) the power ratio P.sub.r of the first power level to the second power level, is selected so that the chlorine-containing etchant gas ionizes to form dissociated Cl.sup.+ plasma ions and non-dissociated Cl.sub.2.sup.+ plasma ions in a number ratio of at least about 0.6:1. The increased amount of dissociated Cl.sup.+ ions relative to non-dissociated Cl.sub.2.sup.+ ions etches the multicomponent alloy on the substrate at an etch rate of at least about 500 nm/min, without forming etchant residue on the substrate.