hi Lior,
as I know, it is not possible to reduce the CTE mismatch betwenn silicon
and photosensitive glasses because of the composition of this kind of
glasses. There is a research group at the Technical University Ilmenau,
Germany dealing with this subject. You can contact Mr. Alf Harnisch,
e-mail: [email protected] 
By the way, it is also possible to structure pyrex or any kind of glass
by sandblasting. For information contact:
Little Things Factory 
Germany
Regards Heike