Chemical deterioration of Al film prepared on CF4 plasma-etched LiNbO3 surface

The fabrication process of an Al thin-film optical polarizer on LiNbO3 wave guides after CF4 plasma dry etching of a previously deposited SiO2 buffer l ayer was investigated. The problem in this process is a precipitation of co mpounds containing C, O, F, and Li on the etched LiNbO3 surface and a chemi cal deterioration of the Al caused by a reaction with these precipitates. M ost notably, the growth of amorphous phase in addition to the crystalline A l metal grains and a partial oxidization of Al were found at the interface using transmission electron microscopy and x-ray photoelectron spectroscopy .