Hi all
I was wondering if someone could help me.
I am trying to etch SiO2/Si3N4 membranes in 100 Si wafer.  The thickness
of the Si3N4 and thermal oxide layers are  100nm
and  2.5micron, respectively.
The Si3N4 layer is removed by the  RIE ,  while  SiO2 in BHF and
then etched in KOH to produce the window membrane. Unfortunately,  each
time I repeat my process the membranes brake.
 Could someone  advise me why this is happening and suggest solution to
this problem.
Also, what are  the best conditions for fabrication of the SiO2 membranes?
Thank you very much in advance.

Maryla