Is copper oxide removal from wafer required before plating?April 25, 2012
Q. I'm just looking for some information on pre-treatment of wafers before they get electroplated with copper.
The process I am working on involves plating copper onto a copper seed layer. The pre-treatment involves immersion in water followed by immersion in sulphuric acid. The thinking is that this is needed to remove copper oxide. However from reading this website and lots of others I can't see this ever being raised as an issue. Lots of sites mention dipping wafers in deionized water but no other "cleaning" step before plating. So is it possible to plate onto copper oxide, or is pre cleaning really an issue as the plating bath is acidic anyway? Really appreciate any help
- Sydney, Australia
A. Sarah, When electrodepositing onto a substrate, adhesion is achieved by the bonding of the coating material to the substrate. Copper oxide is a thin layer on top of copper, so your deposit will be adhering to the copper oxide and will be much weaker than if it was attached directly to the copper. I was always taught that "cleanliness is next to Godliness" - since I have worked in the electroplating industry I have learnt that "cleanliness IS Godliness". Yes, you do need to remove the copper oxide to get a good bond.
R&D practical scientist
The Pheasantries - Chesham, U.K.