Hi,
I planed to stop the KOH wet etching by the buried oxide layer of SOI
wafer. But every time when I did the experiment, KOH just etched through
the oxide layer. The oxide layer is about 1 micron thick, with 2 or 10
micron 100 silicon on top. According to some references, it should be equal
to 300-400 microns silicon in 30wt% KOH solution @80 degree. But everytime
I did the experiment, I just saw the reaction kept going and going, and
suddenly etch through the wafer. (By seeing the bubble of reaction. I
assume that the bubbling will decrease or even disappear when reaction
reached to the oxide)
Any explain or suggestion will be really appreciated.

Thanks a lot!

Peng Yao
DOEs lab
Electrical Engineering Dept.
Univeristy of delaware
Newark D.E 19716