In this letter, we report the relationships between polymerization on Si substrates and the generation ratio for reactive species in fluorocarbon plasma, and reveal essential points for SiO2 etching selectivity to underlying Si. The SiO2 etching selectivity to underlying Si is determined by both the fluoropolymer deposition rate and the sputtering rate on underlying Si. The sputtering rate strongly depends on the F atom concentration in the polymer. Conversely, the deposition rate depends on the CF2 radical density in the plasma. Therefore, control of the generation ratio of CF2 radicals to F atoms is needed to realize highly selective SiO2 etching.
ASJC Scopus subject areas
- Physics and Astronomy(all)