Hi Lisen,

I had the same problem some time ago. Luckily for me the Al
layer was on the backside and the pattern I was developing
was on the front side.

So I protected the  backside of my wafer (Al pattern) with a
blanket coat of AZ 1512 (thinner than AZp4620) and then did
the lithography and development on the front side with
AZp4620 and AZ400k developer. After this to remove the
protective layer on the Al side I did an O2 clean in the RIE
for 5 mins. This easily removed the resist on the Al side
leaving the pattern on the frontside intact.

If you have both patterns on the same side then you might
want to take into account the Al etchrate while designing
your mask.However if you have only 1 pattern in Al (and no
other lithography steps) then the unexposed resist should
protect the Al in the places you want it pretty well.

Hope this helps

Goodluck
Anupama


> Hi,there,
> Anyone has experience with patterning Al. I got
> problem when developing the photoresist, the Al layer
> is etched by the developer. I tried SHipley and AZ
> resists, but both have the same problem. THanks
> Lisen
>
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