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. >>> liuxuchun2@yahoo.com 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/ _______________________________________________ mems-talk@memsnet.org mailing list: to unsubscribe or change your list options, visit http://mail.mems-exchange.org/mailman/listinfo/mems-talk Hosted by the MEMS Exchange, providers of MEMS processing services. Visit us at http://www.mems-exchange.org/