Rob,

There are many ways to inspect the bond quality of bonded substrates, I will
list the methods covered in Chapter 3 of "Semiconductor Wafer Bonding," by
Q.Y. Tong and U. Goesele.
1)      Infrared microscopy
2)      X-ray Topography
3)      Magic Mirror Method
4)      Interface Etching
5)      Transmission Electron Microcopy
I use IR inspection and find the results to be acceptable and the cost for
the entire set up to be relatively low.


Best Regards,

Loren St. Clair

EV Group-Technology, Tel: (602) 437 9492 x 109, Fax: (602)437 9435
E-mail: l.stclair@evgroup.com  ,
Web:www.EVGroup.com  , Date: 9/30/2000


                -----Original Message-----
                From:   Robvk [mailto:robvk@ix.netcom.com]
                Sent:   Thursday, October 19, 2000 2:15 AM
                To:     MEMS@ISI.EDU
                Subject:        Inspection of bond quality

                Does anyone know what the best way is to inspect the quality
of a
                fusion bonded wafer as far as bond voids is concerned:
                    1. IR microscopy?
                    2. Scanning Acoustic Microscopy?

                Is there some good commercially available equipment for
each?

                Thks,

                Rob.