Surface Evaluation of LiNbO₃, LiTaO₃ Crystals Etched Using Fluorine System Gas Plasma RIE

Abstract

Etching characteristic LiNbO₃ and LiTaO₃ single crystals has been investigated using plasma RIE with mixture gases of CF₄/Ar, CF₄/H₂, CF₄/Ar/H₂. The etched surface was evaluated by means of atomic force microscopy and X-ray diffraction methods. The in situ surface temperature of the sample during RIE was measuresd. F atoms exist in the contamination layer, such as sediments, on the surface etched using the mixture gases of CF₄, Ar and H₂ gases. The etch rate was dependent on the orientation of a crystal. The etch rate of LiTaO₃ was less than that of LiNbO₃.