Happy New Year!

I think it might be helpful to keep you guys posted about my testing.
Today, I used a larger container for SU8 developer ( I used to use a
4in glass petri-dish) and refresh developer after each use. The
fabrication process is the same as before.

For the first sample, 1 min of development is barely enough. I can see
the trace amount of residual remaining in the channel. So I continue
the development in 2nd fresh batch of developer for 15 sec. The
channel is clean now, but the bright spot appeared at the acute angel
of the Y shape channel. This is at least better than the picture I
posted in the original message where the channel is surrounded by
bright spots.

For the second one, I do the development in the first batch of
developer for 1.5 min, then need to remove some trace residue in a
second batch for 15 sec. No bright spots found in this case.

For the third one, I switched back to petri-dish. 90 sec development
followed by 45 sec development in two petri-dishes cannot fully remove
the trace amount of PR in the channel. I did a 30 sec rinse in a large
beaker with fresh developer and the result was better. And no bright
edge in this case.

For now, it seems that using more developer might help. However, I
compared the difference between beaker and petri-dish about 2 months
ago, and at that time, there was no difference -- see bright edges in
both cases.

Anyway, thanks for reading this message and any further input would be
greatly appreciated.


Best,
Liu Yu