Reactive ion etching process of SiO2 film using on-site synthesized C2F4 from CF4

C2F4 is a potential etching gas for high aspect ratio etching of SiO2 films owing to its high etch rate. However, it is difficult to fill C2F4 to a gas cylinder with high pressure for mass production due to its high reactivity. To overcome this problem, we developed an etching system, where the on-site synthesized C2F4 from CF4 using a VHF plasma was supplied directly into the etching reactor. It was demonstrated that SiO2 etching using synthesized-C2F4/O2/Ar gas mixture plasma was carried out successfully and the etch rate became 2.7 times higher than that of CF4/O2/Ar gas mixture plasma.