Z.Z.,

The use of a dry etch usually requires chlorine chemistry in an ICP.
Sometimes BCl3 is used instead of Cl2.  It is difficult to suggest a
recipe because it is very dependent on the tool you are using.  There
are many papers written on this topic to suggest starting points, but
the key is to remove all the volatile compounds by adjusting the gas
ratios and the rf/icp power ratio.  If you have the tool, you can
perform a DOE to help identify the key etch conditions.

Brad Cantos


On Nov 12, 2008, at 10:10 AM, Zhaoyu Zhang wrote:

> Thank you Brad and Edward!  Ideally, I would like etching rate
> difference within 20% for both p-AlGaAs and n-AlGaAs.  I thought
> about using vapor and maybe dry etch to cut the current path.  Any
> good suggestion on that? I don't even know if anybody has done that
> before.
>
> Thanks again for your valuable input!
>
> Z.Z