I can vouch for this. Plastic containers can be the source of many
process problems from adhesion to corrosion due to outgassing. I have
seen many cases over the years.

Ed

-----Original Message-----
From: mems-talk-bounces@memsnet.org
[mailto:mems-talk-bounces@memsnet.org] On Behalf Of Wilson, Thomas
Sent: Thursday, January 15, 2009 6:01 PM
To: General MEMS discussion
Subject: Re: [mems-talk] Lifting-Off 1um metal


I once experienced adhesion problems with sputtered aluminum (~100-nm
thick) onto polished single crystal (100) silicon die. It turned out
that only the bare silicon die with poor silicon/aluminum lift-off
adhesion, had been stored in plastic containers (black plastic 4x4 snap
clip packs) for over one month ... apparently the plastic out-gassed
onto the silicon. Other die from the same plastic containers, when
cleaned in a 1-minute piranha followed by an 10-sec HF dip, had
excellent adhesion after liftoff.

Thomas