Hi guys I am having a difficult time dealing with NR9-1000P lithography on
glass substrate (1mm thick) coated with Cr/Au (50nm).

It is a clear field mask, so only the pattern region (5um lines) are not
exposed and developed away

spin coat thickness is 1um at 3000rpm


I found that, when exposing using MA6 Ch1 (7.5mJ) for 20s, line will be
almost closed out. But if reduce the time, the bottom may not get enough
expose.

Could anyone suggest the way to optimize the process?