Langmuir probe applications in monitoring of plasma etching

摘要

The purpose of the paper is to investigate the measurable variations in chemistry of SF_6/O_2/Ar plasma due to etching through layers interface of structure poly-Si/SiO_2/Si. The noticeable magnitude and sufficient stability in some single parameters deference make it possible to develop application of Langmuir probe as implementation of a simple end-point-detection technique. The proposed method is based on the established idea that the surface reactions involved to the process of etching lead to dramatic changes in some parameters of the charged plasma species during die process. Particularly it was found that the densities of electrons and ions and the electron temperature are affected. It was shown that effective electron temperature and electron energy distribution function of the reactive gaseous mixture differ greatly from those of Ar plasma under the same excitation conditions. An approach to wafer-surface charging minimization by varying excitation settings and EEDF was proposed.