STUDY OF CF4, C2F6, SF6 AND NF3 DECOMPOSITION CHARACTERISTICS AND ETCHING PERFORMANCE IN PLASMA STATE

The decomposition characteristics and etching performances of CF4, C2F 6, SF6 and NF3 in their plasma state were studied for use as self-clea ning gases in plasma-enhanced chemical vapor deposition (PE-CVD) equip ment. The study revealed several important characteristics of these ga ses. The plasma decomposition ratios are in the order of C2F6 > NF3 mu ch greater than SF6 > CF4. A large amount of CF4 is formed as a result of the decomposition of C2F6. The decomposition ratio of these gases is strongly dependent on the plasma power density, but; not appreciabl y on the temperature in the range of practical use. Moreover, the rate of F decrease of etchant through the plasma chamber appears to strong ly correlate with the etch rate.