Hi All,

 I'm electroplating 5um of Cu onto a Si wafer using a 50nm/100nm Cr/Cu
seed layer under a resist mould. Does anyone know how I might be able to
etch off the seed layer  with wet etching, while protecting the fine
features (~4um lines) on the wafer? The chrome and copper etchants I
have used so far have massive undercut rates such that to etch off even
100nm of  Cu, the lateral undercut is many microns. Would ammonium
persulfate help in reducing the undercut rate?

Thanks very much.

Best regards,
Sanjay

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--
Dr. Sanjay Vijendran
Research Associate

OSD Group
EEE
Imperial College
Exhibition Road
London SW7 2BT
United Kingdom

Phone: +44 207 5946242
Fax  : +44 207 5946308