Comparison study between optical emission spectroscopy and x-ray photoelectron spectroscopy techniques during process etch plasma

This paper describes the complementary study of plasma-emission wavelength by optical emission spectroscopy (OES) and the experimental results collected from an x-ray photoelectron spectroscopy (XPS) directly over the etched wafer. We have monitored two kinds of etch processes, where the chemistry used was based on CF₄, He, CH₂F₂, and HBr, O₂. Additionally, the study was carried out across a typical silicon wafer and across a silicon wafer with a coating layer of hydrogenated amorphous carbon (a-C:H) which is used in semiconductor manufacturing as a mask layer to etch very small dimensions. The study done by OES along with XPS analysis was compared in order to propose a mechanism of formation of the radical during the plasma etching processes.