Using a quartz crystal microbalance for low energy ion beam etching studies

A quartz crystal microbalance (QCM) has been used for etching yield measure ments in a low energy ion beam system. The goal is to obtain etching yields for ion energies below 150 eV for various ion chemistries and target mater ials. Typical beam currents are about 0.5 mu A, and the mass change per uni t time on the QCM is much smaller than that for typical QCM applications, A number of problems with the application of a QCM were encountered and a de scription of how they were overcome is presented in this article. Quantitat ive etch yield results for the etching of two different photoresists and Si O2 down to 25 eV ion energy are presented. (C) 2000 American Vacuum Society . [S0734-2101(00)04101-4].