Hi, Maybe the only feasible way to etch through Pyrex (i supposed 500um thickness)is to deposit LPCVD amorphous silicon 400nm& PECVD SiC 500nm. These double layer mask can etch deep trench and through holes on pyrex glass. The etchant is HF(5%) & H3PO4(70%. the wafer is safe nearly 10 hurs in solutions. good luckly. Dlee Mechanical Engineering Department The Univeristy of Texas At Austin _________________________________________________________________ Add photos to your e-mail with MSN 8. Get 2 months FREE*. http://join.msn.com/?page=features/featuredemail