Etching mechanism of LiTaO₃ crystals in CHF₃/Ar plasma

Abstract

CHF3/Ar plasma was used to etch LiTaO3 crystal by inductively coupled plasmas technique. X-ray photoelectron spectroscopy was performed to investigate the etching mechanism. It was found that chemical reactions had occurred between the F plasma and the Li and Ta metal species, forming the corresponding fluorides. Some fluorides are nonvolatile, and remained on the surface during the etching period. In order to get higher etching rate, it is important to remove these metal fluorides. The combination of chemical reaction and sputtered etching was performed and could effectively remove the remaining residues.