Surface Modifications of Electronic Materials Induced by Plasma Etching

Abstract

A review of in situ x-ray photoelectron spectroscopy studies of fluorine-based plasma etching induced surface modifications of several electronic materials, but primarily single-crystal silicon, is presented. Post-plasma surface analysis of vacuum-transferred etched specimens has been conducted in an ultra-high vacuum surface analysis chamber connected via a load-lock to the etching chamber. The achievement of SiO2/Si etch selectivity because of different formation rates of a passivating fluorocarbon film which controls the etching behavior and in general the substrate dependence of the fluorocarbon film formation rate is discussed. The post-plasma in situ surface analysis methodology has been extended to the study of realistic semiconductor microstructures after reactive ion etching. Spatially resolved in situ x-ray photoemission spectroscopy of the surface chemistry of a photoresist-patterned silicon dioxide on silicon contact hole etching process has been undertaken by utilizing the topography and conduction characteristics of the realistic microstructure. Often, dry etching processes are followed by a cleaning treatment in order to prepare device quality surface conditions. The dependence of the efficiency of conventional oxygen plasma/wet oxide removal cleaning treatments of reactive ion etched (RIE) silicon surfaces on RIE operating conditions has been studied. The composition and extent of reacted surface layers, e.g., the competitive formation of fluorides or oxides in CF4/O2 discharges, have also been reviewed in the present article. © 1989, The Electrochemical Society, Inc. All rights reserved.