Dear Onny,
The Al is over the SiNx so it can't be leaving a residue on
the polymer and so it shouldn't have an effect. Though if you want to
try a different metal, give it a try. It would likely give some insight
whether the test is successful or not. I patented a stupid process years
ago with Al over polyimide and got it to life off quite easily in an old
Tegal etcher.
You say, "But the cantilevers in sample no. 1 seemed stuck to the
substrate." I would SEM them and see what is actually happening. It
might be that the Al/SiNx ribbon is flexing downward or falling
downward. Or doing polymer removal the stip is curling down at the
edges. (rather fanciful speculation I know.) A SEM could be very
informative.
Again, try NMP it will clean off easily resist burnt on hot plates,
labels, attack clean room gloves and most everything.
I am assuming your process is:
1. Spin polymer
2. Deposit SiNx
3. Deposit Al
4. Photomask pattern.
5. Etch Al (Plasma or wet?)
6. Etch SiNx
7. Strip photoresist? (wet or plasma?)
8. Oxygen plasma undercut.
Ed
-----Original Message-----
From: mems-talk-bounces@memsnet.org
[mailto:mems-talk-bounces@memsnet.org] On Behalf Of onny setya
Sent: Friday, January 30, 2009 9:30 AM
To: General MEMS discussion
Subject: Re: [mems-talk] hard ashing polymer (if Al deposited):possible
isotropic etch by ICP?
Hallo Ed,
thank you for your info. Yes, I use the polymer (not polyimide but
nanoimprint-polymer) as ´sacrificial layer´, so its layer is underneath
the SiNx (or any dielectric), and Al is deposited on the SiNx and then
the polymer should be removed after that.
I have compared 2 samples for 3h undercuting using an asher:1) with Al,
2) without Al.
The structure we investigated _to check the undercuting process_ looks
like a cantilever ca.100µm in lenght, 10µm in width. All of them in
sample no. 2 are peeled off. But the cantilevers in sample no.1 seemed
stuck to the substrate.
I will try to undercut the 1st-sample much longer. or maybe we need to
use other metals to replace Al?
regards,
Onny