Analysis of Plasma Wall Reactions Using Virtual Optical Emission Spectrometry Signal during Dielectric Etching

Abstract

We confirmed that the SiN etch rate uniformity depends on not only the spatial distribution of the H radical density which is strongly affected by loss rates on chamber walls but also time-dependence of the loss rates. We developed a numerical simulation method for plasma–wall reactions to predict both the spatial distribution of the H radical density and the optical emission intensity observed from the view port during dielectric etching. In comparing experimental optical emission spectrometer (OES) data with virtual OES (our simulation), loss probabilities of the H radical on the Si, SiO 2 , and C–F polymer surfaces were estimated to be 0.5, 0.06, and 0.1, respectively. We successfully predicted SiN etch rates under various wall conditions by considering the spatial distribution and time-dependence of the loss probabilities.