Given his requirement of vertical sidewalls with >12:1 aspect ratio,
I don't think HNA is even an option. KOH etch is pretty much the
only reasonable choice.

However, he needs to be reminded that he will have to align the
crystalline faces well with the features on his mask and that he will
only get vertical walls in one direction.

Best
Leo

On Tue, Aug 18, 2009 at 2:41 PM, antwi nimo wrote:
> he must try all.  KOH is also a good option for sure.  KOH, DRIE or
HF+HNO3+wafer...the one which works best.
>