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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.

The Faraday rotation of a ferrimagnetic calcium-bismuth-vanadium iron garnet sample has been measured in the wavelength range 1-5.5 pm. The results suggest that the vanadium and bismuth ions do not each occupy only one lattice site, but that these ions can occur in more than one valence state and can each partially occupy two lattice sites.