We are using a somewhat dated Lam etcher (autoetch 490) as an oxide etcher
and it has developed a peculiar problem. Occasionally, (and it is more
frequent than desired) it will break SOI wafers. The best diagnosis seems
to be that the wafers are sticking to the platen. This sticking problem
happens to both double side polish (DSP) and SSP SOI wafers, and also to
non-SOI dummy wafers. However, the thin (380 um) SOI seem to be weaker and
so they break when the lifting fingers try to raise the wafer from the
cathode. (we have manually unloaded some wafers after etching and it takes
quite a bit of effort to pry them from the cathode). Has anybody
encountered this before and is a solution known?
Thanks

James Dekker, Research Engineer
VTT Microelectronics Research center
Tekniikantie 17, Espoo
P.O.Box 1208, FIN-02044 VTT, FINLAND