Dear Gregg,

Here are a few tips for etching GaAs:

Stop with the HCl.  It makes the wafer rough and I don't see your purpose for
needing this step.
Use more Ar that Cl2.
If you don't have a real reason for the silicon or quartz, get rid of them.
Wafer temp is very important.
The hotter your sample gets the faster it will etch
Cl2 seems to always leave me with a rough finish.  I switched to BCl3 (2 sccm)
Ar (8 sccm) @ 20 watts RIE only.  This is much slower, but very smooth.

Brent


Greg Chance wrote:

> Dear all
>
> I'm having a lot of trouble with the dry etching GaAs. Using a CL2 @ 15
> sccm, Ar @ 4 sccm, 4 mTorr pressure, Power RF @ 200W, ICP @ 200W, and a
> de-oxidised silicon wafer on a quartz platter. The surface is very rough
> and etch rate seems to diminish with etch time. The GaAs is de-oxidised in
> HCl and were using Ti as a mask (600nm) for the etch. I need to etch about
> 30um.
>
> Any suggestions?
>
> Regards
> Greg Chance
> Physics Department
> Bath University UK
>
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