Quantitative analysis of optical emission spectroscopy for plasma process monitoring

Abstract

Plasma parameters should be evaluated to control the plasma process adequately with non-invasive method, one of which is the optical emission spectroscopy (OES) measurement. Some OES studies are reviewed to measure electron density N e, electron temperature T e and electron energy distribution function (EEDF) of argon plasma with low-electron temperature (T e ∼ 1−10 eV) under not only low-pressure condition but also atmospheric-pressure discharge. The basics and applications of a method are described using the "collisional radiative model." The methods to deduce the plasma parameters are explained in terms of detailed description of kinetic balance of excited states with elementary processes in the non-equilibrium plasma. In addition, research results on the measurement method of electron temperature, density, and EEDF are introduced for the measurement of atmospheric-pressure non-equilibrium plasma using OES measurement of continuum emission.