Dear friends,

Have you etch through the whole wafer in a deep trench etcher without using
a dummy wafer as a carrier below the device wafer? If you used SiO2 layer
as etch stop, how thick did you make your SiO2 layer? Is it possible that a
SiO2 layer of 1um might explode right before etching is through because of
the Helium pressure from the chuck? Thank you very much.

Best,

Sun