Etching Charactristic of LiNbO3 Crystal in Fluorine System Gas Plasma RIE

Abstract

Plasma etching characteristic of LiNbO3 has been investigated. Etch rate increased in propotion to the atomic weight of inert gas in CF4+inert gas(He, Ne, Ar) plasma. Etch rate increased by removing a mixing layer, such as LiF, by an ion bombardment effect in CF4+Ar plasma. As etch rate was extremely low in Ar+H2, it was understood that F radical is contributing to etching of LiNbO3. Etching profile of the surface of crystal by CF4+Ar+H2 plasma was remarkably smooth similar to the non-etched surface. An anisotropic etching that had a high aspect ratio could be materialized in CF4+Ar plasma. Futhermore, waveguide pattern that had a comparatively high aspect ratio and etching profile of the surface was smooth could be realized in CF4+Ar+H2 plasma.