Talk to Karl Suss, Inc. in Waterbury Vermont and ask for Joe Brown, or
call their Phoenix office and ask for Jim St. Leger or Klaus Ruhmer.
They make systems with what they call "inter-substrate alignment" that
achieve a precision on the order of one micron (one-sigma) for distances
of 60 millimeters.  KS has a number of alignment systems across the
country, some of which are equipped with this feature.  They may be able
to help you -- they will certainly know where the nearest properly
equipped aligner is located.

Thor Osborn, Ph.D.
Manager, MEMS Processing
Microvision, Inc.
2203 Airport Way South, Suite 100
Seattle, Washington 98134

TEL.    (206) 623-7055 (Main Office)
TEL.      (206) 685-6649 (Fab Office)
FAX     (206) 467-8120


-----Original Message-----
From: Alexander Shenderov [mailto:ashend@bellsouth.net]
Sent: Wednesday, March 03, 1999 9:28 AM
To: MEMS@ISI.EDU
Subject: ALIGNMENT OF FAR-APART WAFERS


Dear all:

I have a problem aligning two glass substrates with a pattern of
transparent electrodes on each.  The wafers need to be  arranged
face-to-face through a gasket 25 to 100 microns thick (obviously, with
holes in it).  The electrode arrays on the opposing sides of the
resultant chamber need to oppose each other to within few microns
(optimally, a micron).

Trouble is, you can not see the electrodes on both sides at the same
time - they are waaay too far apart.

Any suggestions will be highly appreciated.  In particular, does anybody
know a manufacturer who could do such alignment?  I am in RTP, NC - if
you know several locations.

Thank you all.

Alex