It is possible that you had an effect of material diffusion or re-deposition during the DRIE process, which would make the oxide more resistant to BHF. Elina > On Jul 19, 2010, at 2:29 PM, antwi nimo wrote: > > Hello Friends, >> >> I was wondering if there are some silicon-dioxide which will not etch in >> BHF(31°C). >> >> I was etching the buried oxide of an SOI which has the device layer >> DRIE'ed and >> i experienced this suprising effect whereby some of the oxide is somewhat >> resistant to the BHF. most of the oxide is etched but on some parts, there >> is >> still oxide which seems to be resistant to the BHF. There has not been any >> high >> temperature oven process either......so i cant explain this effect. >> Has anybody experienced this effect and possible explanation why some >> silicon-dioxide will not etch in BHF. >> >> thanks in advance. >> Nimo >> Elina Kasman Process Development Engineer, R&D Engis Corporation Click to visit our newly redesigned website www.engis.com Phone: 1(847) 484-7225 E-mail: ekasman@engis.com