Have you tried a hard bake prior to SiO2 etch?

Ed

-----Original Message-----
From: mems-talk-bounces@memsnet.org
[mailto:mems-talk-bounces@memsnet.org] On Behalf Of Taekyung Kim
Sent: Friday, January 30, 2009 11:11 AM
To: mems-talk@memsnet.org
Subject: [mems-talk] PMMA or ZEP resist adhesing promotion


Hi folks,

I have an adhesion issue with PMMA.

PMMA 495 C4 was spun on a thermal oxide substrate and after e-beam
lithography, 6 um x 10 um window was opened. Instead of dry etching, I
wanted to wet etch SiO2 (~50nm thick) with 1:6 BOE (etch rate ~90
nm/min).But the problem is after wet etching and PMMA removal, the
pattern is no longer rectangle. It's close to an oval shape. I think
it's because the adhesion of PMMA layer to the substrate is not goo. Is
there any way to improve adhesion?

What if I use ZEP resist? Is there a way to improve ZEP adhesion to SiO2
substrate?

Thanks

TK