Etch to Cu in PQuest ?

Jim McVittie mcvittie at cis.Stanford.EDU
Mon Feb 14 16:56:19 PST 2005


Here is the reply I got from Gigi about using copper in the PQuest.  

"I remember from Evan's exeperiments that any copper exposed to (Cl) etch
will mess up completely the wafer: that's what happened when even a
little corner of copper taper was left exposed to the plasma. Maybe Evan
can say a bit more about that...
That's all I know about copper"

Since the III-V users use copper tape in the PQuest, copper is not a 
problem to them from a device viewpoint. However, as pointed out above Cu 
can affect GaAs etching. I will contact Evan to see if follow wafers saw 
any affect from the Cu.


On Fri, 11 Feb 2005, jim kruger wrote:

> Jim,
> Would it be permitted to etch sputtered SiN (500 A) to
> stop on Cu (1000 A, on Thermal SiO2/ Si) in PQuest? 
> The etch chemistry is based on the GaAs recipe, 2
> mTorr, Ar15, BCl3 5, Cl2 10 with 200 watts uWave and
> 40 watts RF for 45 or 50 volts DC bias.  
> The etch mask is ZEP 520a e-beam resist, with sub
> 100nm critical dimensions - aiming for very small
> pattern transfer.
> The open area etching to Cu is only ~ 1% of the ~2x2
> cm chip mounted on a 4inch Si carrier wafer with a
> high vac compatible electron microscope Carbon
> adhesive dot.
> Since the area is so small, the bias is so low, and
> the Cu would be exposed only in over-etch, little Cu
> would be left in the chamber, certainly less than
> exposed when others are using approved covered copper
> tape in the Pquest.
> jimkruger
> Mark Wendman
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Jim McVittie, Ph.D.    			Senior Research Scientist 
Allen Center for Integrated Systems     Electrical Engineering
Stanford University             	jmcvittie at
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Stanford, CA 94305-4075			Tel: (650) 725-3640

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