Badin,

I am guessing that the patterns are located on the outside (i.e., non-bonded)
surface of the Pyrex wafer.  To align this, you'll want to look at using an
aligner system that features optical backside alignment (for example, the EVG620
mask aligner).  IR can be a little touchy, especially with doped materials.
Additionally, trying to use IR also brings the difficulty of trying to align two
structures (the alignment keys on the back of the Pyrex to the mask above the
wafer stack) that are separated by a fairly long distance (silicon + Pyrex ~ 1mm
- or more - thick).

Using backside alignment microscopes on an EVG620, you could achieve alignment
of better than 1 um.

Best Regards,
Chad Brubaker

EV Group       invent * innovate * implement
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