Hi, all

I am using SU-8 2050 for my microfluidic pattern, but got the problem
during the align process that the SU-8 coated sample keep sticking on
the mask. The SU-8 sample preparation procedure I took was,

1) Spin coat SU-8 at 3000rpm accelated at 1000rpm for 40s (suppose to be 40um)
2) Pre bake at 65C for 3 mins and then 95C for 5 mins (hotplate)

After this, I use MA8 to align and exposure my sample. I took Hard
mode first, the align gap set at 100um, however, the sample get
sticked on mask. Then I clean the mask and redo by setting the
exposure mode at prox, and align gap at 150 um, exposure gap at 150
um. However, the sample still get to stick on mask. During both
processes, I noticed that the sample will always contact the mask
first before the microscope come down for alignment. I do not know
whether this is the reason that my sample will stick on mask. If so,
how can I adjust the MA8 not to get the wafer and mask get contact
throughout the entire process?

I am also thinking whether my baking time is too short that making the
SU-8 so sticky? Normally how long it cost to get the SU-8 2050 ready
for the exposure?

At the same time, there was a SU-8 bead along the edge of my irregular
sample. Does anyone know how to remove this in a clean way. I I have
tried using wipe to remove it shading with a glass slide, but the
result is not that clean.

Thanks a lot!

Steven