Dear Frank, Thanks a lot for your advice. We have a bulky ring already around the wafer and the wafer is placed on a sample holder which is conductive. but i have notice indeed that the rough edges occur on the side where there is a large area of photoresist. as oppose to the sides close to another plating window. It is interesting. we are investigating as well different ways of agitation. Best regards Magali Frank Rasmussen wrote: > Dear Magali, > > This is a common problem for all DC electroplating processes. The problem occurs due to crowding of current lines near the edges of the plating mould (increased current density near the edges). In case your plated structures are separated by large areas where plating does not occur, this phenomenon will be even more pronounced. A possible solution is strategic placement of dummy structures on your mask layout. These structures will then act as "current thieves" during plating, thus resulting in a more even plating of your structures. This can also be combined with at bulky metal ring around your wafer during plating that - if properly connected to the power supply - will act as a global "current thief" resulting in more parallel current lines between anode and cathode (the wafer), and thus a more even plating. > > Another solution is to convert from DC plating to pulse reversal plating. During pulse reversal material will primarily be dissolved from the regions tending to overplate, thus causing more even plating of your structures. However, please note that some electrolytes are not compatible with pulse reversal plating. > > Best regards, > Frank > ------------------------ > Frank Engel Rasmussen > Industrial Ph.D. student, MEMS research group > Mikroelektronik Centret > Oersteds Plads > Building 345 (east), DTU > DK-2800 Kgs. Lyngby > Denmark > www.mic.dtu.dk > > -----Oprindelig meddelelse----- > Fra: Magali Brunet [mailto:mbrunet@nmrc.ucc.ie] > Sendt: to 17-10-2002 09:58 > Til: mems-talk@memsnet.org > Cc: > Emne: [mems-talk] Edges problem in through-mask NiFe electroplating > > > > Dear all, > > On a silicon wafer where a Cu seed layer is sputtered, I am depositing > photoresist (8um thick) to create patterns and then electroplating NiFe > through the patterns (5um thick). > > The deposit has an even thickness except at the edges where there is a > big overplating. (kind of > "dog hears") > > Does anyone have an idea on how to get rid of this edge problem? > > Thanks a lot in advance, > > Magali > -- > PEI Technologies, > NMRC, Lee Maltings, University College, > Cork, Ireland. > > Tel: +353 21 4 904279 > Fax: +353 21 4 270271 > email: mbrunet@nmrc.ie > > > > _______________________________________________ > 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.memsnet.org/ > > > ------------------------------------------------------------------------ > Name: winmail.dat > winmail.dat Type: DAT File (application/x-unknown-content-type- DAT_auto_file) > Encoding: base64 -- PEI Technologies, NMRC, Lee Maltings, University College, Cork, Ireland. Tel: +353 21 4 904279 Fax: +353 21 4 270271 email: mbrunet@nmrc.ie