Hi Jukka,

        Is it possible for you to hardbake your PR up to 150C and see if
the adhesion gets better? Al is usually rough, so wet etchant can
penetrate through the "channels" formed by the rough surface. Higher
hardbake temperature should have better adhesion. But then you'll probably
need O2 plasma to strip the resist afterwards.


Isaac

On Thu, 12 Aug 2004 Jukka.Viheriala@orc.tut.fi wrote:

> Hello,
>
> I have been trying to wet etch 300 nm thick Al layer using 2um wide PR
> stripe. However I have problems width adhesion of resist to aluminum. PR
> stripe seems to peal of when I'm etching.
>
> I have been using following process.
>
> 1.    Spin HDMS on wafer (no I can't use vapor prime)
> 2.    Spin 1um thick AZ6612 on wafer
> 3.    Soft bake 2 min @ 110 C on hotplate
> 4.    Exposure
> 5.    Develop
> 6.    Hard bake 3 minutes in oven. 120 C.
> 7.    Etch with wet etchant
>
> I have tried
> HCl:H20 1:2 => very non uniform etching + Resist was removed
> BOE => Resist was removed
> HF:H2O2:H2O 1:1:20 => Resist was removed
> H3PO4:HNO3:CH3COOH:H2O 4:1:4:1 => Resist was removed
>
> Does anyone have good solutions. I know that I can grow SiN on Al and use
> that as an etch mask or use dry etching but these steps make process more
> complicated and I'm designing fast test process to test epi-wafers.
>
> -Jukka Viheriala
>
>
>
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Yours sincerely,

Isaac Chan

Ph.D. Candidate
Dept. Electrical & Computer Engineering
University of Waterloo
200 University Ave. W
Waterloo, Ontario, Canada
N2L 3G1
Tel: (519) 888-4567, ext. 6014
Fax: (519) 746-6321
iwchan@venus.uwaterloo.ca
http://www.ece.uwaterloo.ca/~a-sidic