Hi,

        One of the processes I'm working on involves spin coat / UV
patterning a UV curable Poly Vinyl Alcohol enzyme layer over a Pt electrode.
        One of our inline QC tools (FE3 ellipsometer) indicates that we are
accumlating about 50 angstroms of resist residue from the metallization
process (a combination of liftoff and etch processes). To clean the
electrode surface we have implemented an Argon sputter clean at the end of
our final metallization step.

        Unfortunately, this cleaning process seems to have adversley
affected the surface tension of the Pt electrode such that when we spin coat
a aqueous based adhesion promoter (N-2 Aminoethyl-trimethoxy silane) the
layer does not adhere well to the edge of the wafer. Does anyone understand
the mechanism at work here?
        I would have thought the bare platinum would have become more
hydrophilic rather than hydrophic after having removed the resist residue.
        At any rate, I've implemented a 1% CF4/Ar plasma that has improved
the coat uniformity and adhesion of the ahesion promoting silane layer.
        Is it likely that the fluorine in the plasma is making the Pt
hydrophilic?


> Thanks in advance,
>
> Gerry Overton
> i-Stat Canada
>