Study of CF₄, C₂F₆, SF₆ and NF₃ Decomposition Characteristics and Etching Performance in Plasma State

Abstract

The decomposition characteristics and etching performances of CF 4 , C 2 F 6 , SF 6 and NF 3 in their plasma state were studied for use as self-cleaning gases in plasma-enhanced chemical vapor deposition (PE-CVD) equipment. The study revealed several important characteristics of these gases. The plasma decomposition ratios are in the order of C 2 F 6 >NF 3 ≫SF 6 >CF 4 . A large amount of CF 4 is formed as a result of the decomposition of C 2 F 6 . The decomposition ratio of these gases is strongly dependent on the plasma power density, but not appreciably on the temperature in the range of practical use. Moreover, the rate of F decrease of etchant through the plasma chamber appears to strongly correlate with the etch rate.