Fine Surface Processing of LiNbO₃ Crystal Etched without Mask Using Fluorine System Gas Plasma RIE

Abstract

Etching characteristic LiNbO₃ single crystal has been investigated using plasma RIE (Reactive Ion Etching) with mixture gases of CF₄/Ar, CF₄/H₂, CF₄/Ar/H₂. The etched surface was evaluated by means of atomic force microscopy. The etched rate for -Z surface of LiNbO₃ single crystal was higher than +Z surface using CF₄/Ar and CF₄/H₂ mixture gases. Possibility of the deep etching at the boundary between -Z surface and +Z surface for partially polarization-reversed LiNbO₃ without mask was investigated. The best condition of the deep etching was obtained by using CF₄/H₂ mixture gas. The value of aspect ratio is approximately 1.0 on this condition.