Dear all,

I wrote some months ago because I had problems with etching a SOI
wafer. I tried your suggestions but unfortunately did not get good
results, but finally I found the problem: our SOI wafer has 700 nm of
unexpected oxide on the top!

Have any of you ever heard about something like this?
Does anybody know a RELIABLE SOI wafer supplier where I could buy
wafers in small quantities with a device layer of silicon in the range
of 300-400 nm?

I etched the top with 3% HF, but the surface remains too rough for my
device. Now, I think the best solution is to buy a new wafer, but if
somebody knows of a better etch chemistry to remove the oxide
and get the silicon layer with optical quality it would be also
appreciated.

Thanks in advance!
Jose