Deepak,

Often during any dry etch process, if a powdery film remains it is probably
a nonvolatile compound formed between the etchant and the material etched.
You mentioned chlorine, but did not mention other etch parameters such as
carrier gas, substrate platen temperature, pressure, etc.  I would first
analyze the material with a surface technique (SIMS, Auger or maybe even
EDX).  Once you know what remains, you should be able to adjust the
parameters of your etch to eliminate it.

Brad Cantos


On 9/5/08 8:37 AM, "Deepak Sridharan"  wrote:

> Hello everyone,
>
> I am using an ICP etcher with chlorine chemistry  to etch into GaAs with
> ZEP/ PMMA polymers as the etch mask. After the etch I am seeing a thin layer
> of white film on top, which  seems to go away if you scrath it away with
> hand or wash it with ethanol. However, the film within the small features
> does not seem to go away.
> Has anyone had such experiences before. If so, please do let me know what
> the film is and how it can be removed.
>
> Thanks
> Deepak