Hello Everyone,

I am trying to perform contact lithography experiments and for my
experiments I am using patterns defined in Aluminum thin films as the mask
features (in other words the mask is made of Aluminum) and g-line
photoresist for the resist. Now for the first few runs I get features as
expected in the resist after lithography. However after the first few runs I
see diffraction occuring that is causing the patterns in the resist to be
much larger than the patterns on the mask. I tried using solvent clean to
remove any trace photoresist that may be sticking to the mask. But it
doesn't help. I am not sure if there are any other factors causing the
problem.

Please let me know if you have any ideas for solving this problem.

Thanks
Sreemanth

ps. Thanks a lot for the suggestions for my previous question.