Dear Brijesh,

there are diffirent polymers / adhesives which can be used as an
intermediate layer for bonding purposes. The following samples gives an
overview about the material range: Epoxies, UV-Epoxies, positiv / negativ
photoresist, BCB, PMMA, PEEK, thermosetting coplyesters, PMDS, Polyimides
and Waxes. Practically all types of wafer materials can be joined with
adhesive bonding. The exact bonding procedure depends on the adhesive
material.

A good overview about different adhesive bonding processes gives the
following paper
Low-temperature full wafer adhesive bonding,
by Frank Niklaus, Peter Enoksson, Edvard Kälvesten and Göran Stemme
http://www.iop.org/EJ/abstract/0960-1317/11/2/303

Best Regards,
Margarete Zoberbier