Analysis of product species in capacitively coupled C5F8 plasma by electron attachment mass spectroscopy

The decomposition and reaction products of C5F8 gas in a capacitively coupled plasma have been investigated by electron attachment mass spectroscopy (EAMS). Although only a few species are produced directly from C5F8 molecules by dissociative electron attachment, a variety of species appears after the discharge is ignited. The products comprise not only fragmented species but also polymerized species with larger masses than that of the parent molecule. It has been clarified from the energy spectra of the F- signal that perfluoro-compounds such as CF4, C2F6 and C3F8 are produced through the decomposition of C5F8, followed by secondary reactions in the gas phase. A tendency towards polymerization with increments of CF2 units is also noted.