Badin,

I use the same tool for the same process (300 um silicon bonded on 500 um
Pyrex). You can use clariant AZ6632 (1500 rpm, >5um)  or AZ9260 (2000rpm,
>10um) photoresist and your standard recipes for this kind of process. The
resist will withstand up to 2 hours of processing with 600W coil and 14W platen
power when using an SF6/O2 process. If you have to use a handle wafer due to
holes in your pyrex wafer, you should use AZ6632 with 500rpm (plus EBR or
1500rmp for 1s) and a postbake at 125 °C, furthermore you should decrease the
coil power to 300 - 350 W.
Contact me for any more information.

Marco