I don't think DRIE will give the same smoothness as an KOH etch.

For renil's purpose, I think any concentration between 15%-50% will
work, because <111> surface is usually quite smooth over a wide range
of KOH concentrations.

Best
Leo



On Mon, Aug 17, 2009 at 4:06 PM, antwi nimo wrote:
> if you have the option to use DRIE that will be the best option.  if not then
you can use HF in different concentrations; mostly 50% with water.  that will be
isotropic and not anisotropic; that means not vertical wall but will be smooth
enough i guess.
>
> i hope this helps.
> Nimo

--
Xiaoguang "Leo" Liu
Birck Nanotechnology Center,
Purdue University,
1205 W.State Street, West Lafayette, IN, 47906 USA
liu79@purdue.edu