I am trying to fabricate ridge waveguide on X-cut LiNbO3 parallel to
crystallographic Y-axis.  Initially after depositing Cr-layer of specific
thickness I am doing Proton Exchange in Benzoic acid to activate the
unmasked surface, then I am doing RIE of the activated surface using CHF3
and Ar.  But  after doing RIE for ~ 10 min some white particles are observed
to be grown on the surface, it has been found that the particles is Nb2O5. I
don't have any clue how it is forming during etching and I want to avoid the
formation of this particle.

Can anybody suggest something?

Thanks a lot in advance.

Shantanu Pal
PhD Research Scholar
Integrated Optoelectronics/MEMS & Microelectronics Labs,
Electrical Engineering Department,
Indian Institute of Technology Madras,
Chennai-600036,India.