Mechanisms of etching and polymerization in radiofrequency discharges of CF4–H2, CF4–C2F4, C2F6–H2, C3F8–H2

Abstract

Some results obtained during the etching of Si or the deposition of fluorocarbon films over Si substrates uncoupled from ground in rf plasmas fed with CF₄–H₂, C₂F₆–H₂, C₃F₈–H₂ and CF₄–C₂F₄ mixtures are presented. The polymerization process is explained on the basis of a mechanism which involves CF and/or CF₂ radicals as building blocks as well as an activation of the polymer surface by means of charged particle bombardment. It is definitively proved that the etch rate of Si depends only on the F‐atom concentration, independent of conditions in the various feeds.