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Title: Kinetic studies of SF/sub 6/ plasmas during etching of Si

Journal Article · · Plasma Chem. Plasma Process.; (United States)
DOI:https://doi.org/10.1007/BF00564630· OSTI ID:5347698

Mass spectrometric kinetic measurements were performed on a dc plasma during the etching of Si by SF/sub 6/. Neutral plasma particles were permitted to effuse through an aperture in the cathode, via a differentially pumped section, into the ion source of the spectrometer, the sample being mounted on the cathode. The applied voltage was changed in steps, and the resulting mass signal transients for SF/sup +/ /SUB x/ (x=0-5), F/sup +/, S/sub 2/F/sup +//sub 2/, SiF/sup +/, and SiF/sup +//sub 3/ were recorded. The SF/sup +//sub 5/, SF/sup +//sub 4/, and SF/sup +//sub 3/ signals turned out to be essentially a measure of the unfragmented SF/sub 6/ present in the plasma, while SF/sup +//sub 2/ and SF/sup +/ responded in a complex way to the changes of applied voltage. The rate of SiF/sub 4/ formation was not proportional to the concentration of F atoms or ions present. The S/sub 2/F/sub 2/ present in the plasma was probably formed from SF/sub 2/ and SF radicals, mostly. Slow changes were observed in the signals representing SF/sup +//sub 2/, SF/sup +/, S/sup +/, F/sup +/, and S/sub 2/F/sup +//sub 2/, presumably related to, or controlled by, gradual changes of the surface undergoing etching. The production and consumption rates of various species were seen to be nearly in balance, and strongly dependent on the applied voltage.

Research Organization:
Univ. of Wisconsin, Milwaukee, WI
OSTI ID:
5347698
Journal Information:
Plasma Chem. Plasma Process.; (United States), Vol. 3:3
Country of Publication:
United States
Language:
English