Hi,
I had problems with the adhesion of photoresist on crystalline quartz when
exposing in a double sided mask aligner.  The substrate holder was made of
fused quartz, and thus the photoresist was exposed from the back side due
to internal reflections in the (UV transparent) substrate holder and the
quartz wafer. Placing a silicon wafer between the holder and the substrate
solved some of the problem, but I also had to minimise the exposure time.
Best regards,
Orjan Vallin