Bert,
Use pulse electroplating. In the world of plating, voltage is not the
parameter to watch. It is current. You have 4 variables. positive current for
some time, and negative current for some time. The positive current over time
will grow your copper. The negative current over some fairly short time will
knock off the copper growing on the sidewalls.To start I would recommend doing
the positive current for, say 100 ms followed by the negative current for, say
10 ms. for simplicity you can let the amplitude of the positive and negative
current be equal. The amplitude that you choose should be low enough to
provide a fairly smooth plating with equal thickness across your wafer. In
general, the slower, the better. (This is exactly opposite, of course, to what
the manufacturing people will want.) It's been a while since I've done any
plating so I'm going to guess that you can start with 1 mA / sq cm of exposed
plating area. You should already have a handle on this, however, based on the
plating that you've already done. You would do yourself a big favor if you do
a designed experiment with the 4 variables.
Good luck.
Mike Mattes
Medtronic, Inc.
>>> [email protected] 04/17/02 01:30PM >>>
Hi, Everyone,
I met a problem with Cu electroplating, hopefully
someone can provide me some advice.
The problem is, I want to fill a trench by Cu
electroplating with DC. The size of trench is 10um x
100um. The depth is 5um. Once I begin the plate, it
seems that Cu is growing along the sidewall instead of
filling the trench. I notice that if I grow in trench
for 1um, Cu will accumulate in the sidewall for about
3um above the surface. I wonder if anyone also has
such a problem and what is the answer to this. Someone
suggest me to do it by AC with some duty cycle, does
this method avoid this problem? Usually what is the
parameter for AC plating in the similar case?
Thank you very much and hope someone can give me some
solutiong soon!
Bert Liu
Yahoo! Tax Center - online filing with TurboTax
http://taxes.yahoo.com/
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