Hello.  I'm currently working on creating cantilever beams of poly-silicon.  The
wafers that I've been working with recently are 2um poly, on 2um SiO2, on a
silicon substrate.  When attempting to undercut the beams with BOE, I have had
little success with keeping the beams from collapsing and sticking to the
surface of the wafer.  Has anyone had any experience with a similar approach, or
similar problems?  My first assumption is that it is due to surface tension
forces when drawing the water out from under the undercut section when rinsing
and drying.  Perhaps a different sacrificial layer could be used, and then
utilize a dry etch to undercut?  Any info would be appreciated.

Thanks in advance.

Eddie McCloud
Center for Electronic Materials and Devices @ San Jose State Univ.