>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

The Inter-substrate alignment option of the Karl Suess aligners is nice,
but expensive. My understanding is that modern alignment tools can do
the following (never have used one, but then if I was to built one, I
would do it like this:-)
These aligners have a camera with monitor. You focus on the top surface,
the one to align to. Of course, now your other surface, the one you want
to align to, is out of focus. This top surface image is stored in the
computer, in a semitransparent fashion. Then, you focus on your other
surface. (With your galss wafers, you don't even need as anything fancy
as an ifrared or double-sided aligner, you can look right through.) Now,
you align the current image to the stored one. Extremely sneak, you can
even use the highes magnification you whish.
Now you need such an aligner...
--
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Alexander Hölke, Postdoctoral Associate
     Microsystems Technology Laboratory
     Room 39-663, Massachusetts Institute of Technology
     Cambridge, MA 02139
Phone: 617-253-0724  Fax: 617-253-6906
ahoelke@mtl.mit.edu
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