Effects of the Applied Power of Remote Plasma System With Green Alternative Chamber Cleaning Gas of Carbonyl Fluoride

An effort to find an alternative dry-cleaning process gas with low global warming potential (GWP) has been conducted to decrease greenhouse gas emissions. Carbonyl fluoride (COF2) is one of the candidates as an alternative gas for plasma-enhanced chemical vapor deposition (PECVD) chamber cleaning because of its lower GWP compared to the currently employed $\mathrm {NF}_{\mathrm {3}}$ gas. The dry-cleaning process conditions containing the power amount of the plasma source is related to the dissociation rate of the cleaning gas and dry-cleaning performance. We investigated the effects of the amount of remote plasma power to the chamber cleaning rate with COF2, and its effects with diluted gases of $\mathrm {O}_{\mathrm {2}}$ and Ar. By the comparison of both numerical analysis and experiment, we found that the change of the amount of power induced different production rates of species in the gas mixture. In the case of $\mathrm {O}_{\mathrm {2}}$ dilution, oxygen radicals prevail in the plasma, and it produces stable by-product of $\mathrm {CO}_{\mathrm {2}}$ with the reaction of oxygen radicals to yield more fluorine atoms and radicals. We conclude that oxygen radicals have a significant role in the dissociation of the COF2, production of fluorine radicals, and it helps to reduce the amount of cleaning inhibitors such as C-C and C-F compounds. Additional dilution gases for cleaning gas affect production mechanisms and rates of species.