Laser diagnostics of plasma etching: Measurement of Cl+2 in a chlorine discharge

Abstract

Laser-induced fluorescence has been used to determine the relative density of Cl+2 in a chlorine radio frequency discharge as a function of pressure, flow, power, frequency, and distance from the electrodes. The conditions studied correspond closely to those used in anisotropic plasma etching of materials such as Si and InP. This technique provides quantitative data on ion densities over a wide range of parameters, as contrasted with qualitative methods, such as optical emission.