Plasma etching of copper films at low temperature

Experimental verification of a low temperature (<20 °C), reactive plasma etch process for copper films is presented. The plasma etch process, proposed previously from a thermochemical analysis of the Cu–Cl–H system, is executed in two steps. In the first step, copper films are exposed to a Cl2 plasma to preferentially form CuCl2, which is volatilized as Cu3Cl3 by exposure to a H2 plasma in the second step. Plasma etching of thin films (9 nm) and thicker films (400 nm) of copper has been performed; chemical composition of sample surfaces before and after etching has been determined by X-ray photoelectron and flame atomic absorption spectroscopies.