I will bond three wafers together by using the wafer to wafer
bonding technique. Howerver, all three wafers have patterned and have
etched profiles. I have to align them (say +/-20 micron) before bonding
and keep them aligned during the bonding process.
        Any feedback or sharing your experience on that will be appreciable.

Sincerely,

Levent Yobas
Case Western Reserve U.
Cleveland, OH