Hi Michael,

thanks for your answer, I left the Chip (5*5)mm^2 about 30minutes in hot
aceton (~80°C). Normally, a few minutes are sufficient, but I guess,
that the SF6 changes the surface of the PMMA. Under the SEM, it lokks,
as if there were cobwebs on the structure ...

Stephan

Michael Rust schrieb:
> Stephan,
>
> How long did you leave the sample in acetone?  In my experience, acetone
> works quite well to remove PMMA if you give it enough time (a couple of
> hours if doing liftoff on 2" wafer).  However I haven't used that
> combination of SF6 and Ar so perhaps, as you mentioned, a different
> chemistry is required.
>
> -Mike
>
> -----Original Message-----
> From: [email protected]
> [mailto:[email protected]]On Behalf Of Stephan
> Sent: Friday, July 28, 2006 10:30 AM
> To: [email protected]
> Subject: [mems-talk] To get rid of PMMA that was in a RIE
>
>
> Hi!
>
> After several ebeam lithogarphy steps, where I have patterned
> freestanding structures out of SOI, I want to remove
> selectively some
> parts of the upper Silicon layer. So I spin on resist (PMMA
> 500000, 7%),
> bake it at 170°C for 2 minutes. After ebeam exposure, I
> develop and use
> a RIE ICP with SF6 and Ar (5:10) to etch away the unprotected
> areas on
> the Chip.
> All this works fine, the only problem is, to remove the resist
> afterwards. Aceton does not work properly, some parts of the
> resist
> remain. I can't apply an O2 Plasma, because there are magnetic
> structures on the Chip. This is probably dur to the fact, that
> etching
> does harm to the PMMA layer.
>
> Do you have an idea, how to get rid of the resist?