Si etching rate calculation for low pressure high density plasma source using Cl-2 gas

Abstract

Based on a simplified Cl-2 plasma Si etching mechanism, we calculate the Si etching rate with a comprehensive analysis of the effect of ion bombardment. With its flux distribution, the bombarding ions are regarded as the sum of independent monoenergetic beams (SIMB) approach. The Si etching rate is examined over the radio-frequency (rf) frequency (nu(rf)) range from 1 to 20 MHz (0.1 nu(pi) less than or similar to nu(rf)less than or similar to 2 nu(pi), where nu(pi) is the ion plasma frequency) under the typical low pressure high density plasma condition. To consolidate the SIMB approach, the etching rate is compared with the result from the monoenergetic single ion beam approach. The difference in the Si etching rate between the two approaches is notable at a low rf frequency range. The effect of threshold energy on the Si etching mechanism is also investigated. We conclude that under a low rf frequency, for a precise etching property examination, the effect of the bombarding ions should be investigated through the SIMB approach. (C) 2000 American Vacuum Society.