Dear Alex,
The aligner you described below is a Karl Suss MA/BA6-BSA.  BSA stands for
Bottom Side Alignment.  The alignment procedure works exactly like you
described it.  Utilizing the image storing technology for the alignment is
actually a patented Suss technology.
The ISA (Intersubstrate Alignment) is probably overkill for what you need.
We do have users of this kind of alignment system in RTP.  Please contact
our East Coast guys to find out who.

Regards,
Klaus Ruhmer
Karl Suss
West Coast guy.

-----Original Message-----
From: Alexander Hoelke 
To: [email protected] 
Date: Tuesday, March 23, 1999 3:56 PM
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
>
>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...
>--
>********************************************************
>Alexander Hvlke, Postdoctoral Associate
>     Microsystems Technology Laboratory
>     Room 39-663, Massachusetts Institute of Technology
>     Cambridge, MA 02139
>Phone: 617-253-0724  Fax: 617-253-6906
>[email protected]
>********************************************************
>
>
>
>