Swiss,
Have you considered using an SOI wafer? It would essentially be a thin Si
wafer bonded to a thick wafer, at the beginning of your process, which you
could separate later.

Jesse Fowler
  UCLA/MAE Dept., 420 Westwood Plaza, Room 37-129, ENGR IV
  Los Angeles, CA 90095-1597 | (310)825-3977
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