Any reason you're not using 5 to 10nm gold and then use a mix of KI/I2
gold etch. I have asimilar ebeam process and this recipe has worked well
for me.

To my knowledge, Aluminium is more delicate to remove without moving to
aggressive chemistries that would also affect your pmma.

M.

-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Hyunsoo Park
Sent: Friday, October 13, 2006 2:09 PM
To: [email protected]
Subject: [mems-talk] To remove Al layer from PMMA/glass substrate

Hi guys

I am using E-Beam lithography tool with glass substrate.
The PMMA is coated on glass  and this is not conductive material so I
deposited 5nm Al layer to make it conductive using evaporator.
When I have done EBL and I have to remove Al layer to develpe PMMA.

But problem is here.
I have used NH4OH and diluted HCl.
The Al layer is removed but still remain .
I tested with just glass substrate like Al/glass.
When I soak this into the solution, I can see the color become light
within couple of minutes, I think it means the Al layer is thinner. But
it keeps same color in 30 minutes.

Please tell me the possible solution.