Kinetics and mechanisms of Cl2 or HCl plasma etching of copper

An investigation by experiment and computer simulation is reported into the kinetics and mechanisms of the interaction between copper and impinging reactive species as the former is etched with a chlorine or a hydrogen chloride plasma. It is established that the manner in which etching proceeds is substantially the same for the two parent gases. There are, however, considerable differences in etch rate that are related to those in the types and stationary concentrations of reactive plasma species and in their fluxes to the surface being processed. Two regimes of etching are identified over the temperature range 373-653 K that differ in the character of the etch-rate-temperature relationship and in the shape of kinetics graphs. In a higher temperature regime, the plasma-etching reaction with copper involves complete removal of etch products from the surface; it proceeds under steady-state conditions and is of first order in terms of the concentration of reactive species in the bulk plasma. This occurs at temperatures above 500-520 K for Cl2 plasmas and at above 580-600 K for HCl plasmas. © 2007 Pleiades Publishing, Ltd.