Forming gas plasma may be effective.
Mechanism of this process described in
JECS v141 (1) p192   Jan 1994

Bill Flounders
Berkeley Microlab


Jan Michael Kubr wrote:
> I have a problem in that I cannot get hardbaked PR (SPR-220) of my
> surfaces, both gold and Si.
>
> With the gold sitting on TiW, piranha is not really a feasible
> solution. I have tried long o2 plasma ashes and overnight baths in
> heated prs-3000 with little success.
>
> Any other solutions I can try?