A few thoughts

1.) Your should be using PAE (16-1-1-2) or equivalent to etch Aluminum.

2.) Your need to oxidize the surface of your aluminum before applying
Photoresist. I do it one of two ways. Dehydration bake at 120 C - 200 C
(careful - high temp may cause hillocking), or O2 clean in an asher or
plasma system. Either way will grow a thin oxide and help adhesion. HMDS
will help some, but not usually necessary.

3.) Make sure and hard bake your photoresist ~120 C.


Good Luck,
Charles Ellis,
Director, Auburn University Microelectronics Laboratory


-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf
Of Yinlan Ruan
Sent: Sunday, August 10, 2003 8:12 PM
To: [email protected]
Subject: [mems-talk] Adhesion problem Between Aluminium and Photoresist


Hello Everyone,

We have problems regarding Aluminium mask patterning with wet etching.
We use AZ5214 or AZ1518 photoresist, but Aluminium patterns are always
undercutting when we use Phosphoric acid(85%). It seems that the
adhesion betweem Aluminium film and resist are weak. we do not try HMDS
at present. I would apprecaite any advice with good Aliminium patterns
with wet or dry etching.

With regards

Yinlan Ruan
Laser Physics Center
Research School of Physical Science and Engineering
The Australian National University
Tel:61-2-61254079
Fax:61-2-61250029 _______________________________________________
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