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Need to do Selective Electroless plating (Cu or Ni)

June 10, 2015

Q. Hi,
I've encountered some problems when doing my electroless plating (Cu and Ni) experiment: the samples I used consisted of copper pillars and Cr(seed layer) on silicon dies. When I performed electroless plating (Cu or Ni), it plated both on copper pillars and Cr. However, I only wanted to plate on copper pillar instead of Cr. Then I etched Cr by dilute HCl with Al, underneath the Cr was the Silicon. Once again, it still plated both on copper pillars and Si.

The pretreatment steps followed by cleaning, micro etching, acid dipping, predip, activation by Pd.

Are there any ways that I can do selective plating (plating only on copper but not on Cr or Si)? Please help me with it.

Here is my thought:
In addition, would placing my samples (copper pillars and Si on the top of silicon die) into furnace with 900-1200 °C for growing SiO2 help to block from plating? Or enhancing the layer of Cr2O3 would prevent it from plating?

Thanks all for suggestions.

kevin lee
- san jose, California, USA