Hey Jay,

It seems to be a classic case of poor adhesion.   What's the substrate
and what procedure did you carry out prior to the deposition of the
metal layers?  Also, the 1st layer seems a bit thin for good adhesion.

Trent

Jie Zou wrote:
> Hey everyone,
>
> Using a Photoresist S1813 - LOR3A bilayer, I evaporated about 3nm Cr (as
> adhesion) 120nm gold and 130nm Cr (from bottom to top). Then I lifted it
> off. So far so good. I need to do a e-beam lithography after that. Thus I
> spinned PMMA A4 and baked it @ 180 C (30mins in oven). After I lift-off or
> just washed away the PMMA, I found parts of the metal layer detached and it
> coiled itself. I ran a test that without the PMMA, I directly baked the
> sample with the metal layer on the hot-plate, and the detachment happened
> again. I also tried a sample with only 120nm gold or only Cr layer (and the
> 3nm Cr adhesion layer) baking under the same condition. It is fine.
>
> I think this detachment and coiling is due to the stress difference between
> the Cr and Au, since I don't have any problem with only gold or only Cr.
> When I heated my sample, the two metals extended and release its stress in
> different ways.
>
> Sometimes the first evaporation also failed. I think it was also due to the
> high temperature in the evaporation chamber.
>
> Anyone had the same experience and any suggestion? Is there some annealing
> process I could try?