二元硅氧环与CF_n(n=1～3)自由基反应的理论研究

Theoretical Study on the Reactions of Two-membered Si-O Rings with CF_n(n=1～3) Radicals

用密度泛函理论在UB3LYP/6-31G(d)水平上研究了二元硅氧环与CFn(n=1～3)自由基的反应,弄清了微观反应机理,计算了反应的活化能和反应热.计算结果表明反应按两类相互竞争的机理进行:一类是不涉及C—F键断裂的反应,另一类是Si—O和C—F键同时断裂的反应.CF2自由基与二元硅氧环反应所需活化能最小、驱动力最大,是Si—O键最有效的刻蚀剂,与实验结果一致.

The reactions of the two-membered Si-O ring with CFn（n=1-3） radicals have been studied by using density functional theory calculations at the UB3LYP/6-31G（d） level. Calculated results show that these reactions proceed via either the mechanism without C-F bond breakage or the mechanism with the C-F and S-O bond breakages. The activation energies, reaction heats, and details of the potential energy surfaces for these reactions have been obtained. CF2 radical was found to be the most effective etchant to Si-O bonds. This result is in good agreement with the corresponding experimental finding.