maybe it's not the photoresist but the residue of ICP etching. Have you tried
piranha and have you tried to analyze the composition of the resist?


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>From: "Jason Milne" 
>To: "'General MEMS discussion'" 
>Subject: Re: [mems-talk] PR removal after ICP RIE etching
>Date:Wed, 21 May 2008 12:42:32 +0800
>
>I run into this problem frequently with AZ2035, a negative resist. The
> problem occurs with negative resists if you take the resist above a
> certain temperature (~125C for AZ2035), or if you use CF4 plasma, even
> at low temperatures.
>
> I remove the baked-on resist using hot AZ Kwik Strip, but I imagine
> other photoresist strippers will work. 5 minutes in a bath of Kwik Strip
> with the hotplate set to 100C, and the resist is gone. Alternatively, an
> overnight soak at room temperature seems to work.
>
> The same technique works if the resist gets too hot during a liftoff
> metal deposition. If liftoff fails in acetone, try using hot photoresist
> stripper instead. I have saved many samples this way.
>
> I would recommend trying the overnight soak first, and if that doesn't
> work then make sure you take appropriate precautionary steps when
> heating up Kwik Strip, or whatever stripper you use.