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