Low global warming fluorinated carbonyl compounds for plasma etching of SiO2 and Si3N4

In this work, the plasmas of fluorinated carbonyl compounds such as C2F4O, C4F8O, and C5F10O having low global warming potential (GWP) were characterized for etching SiO2, Si3N4 and poly-Si films. Radicals in the plasma were analyzed by quadrupole mass spectroscopy, and CO and CF3 peaks were identified as major products in the plasma phase. The concentration of exhaust gases were analyzed by Fourier transform infrared spectroscopy, and the global warming effect of the exhaust gases was evaluated by CO2 equivalent values. CO and COF2 having low GWP were identified as the major reaction products in exhaust with fluorinated carbonyl compound plasmas. CF4 having high GWP were also identified as a significant emission due to the abundance of trifluoromethyl group (-CF3) in the molecules. The CO2 equivalent values for the exhaust gases of C2F4O, C4F8O, and C5F10O were lower by up to 78 %, compared to that of c-C4F8 plasma.