Dear sir,

I'm spinning my photoresist (SU-8) on a 1" x 1" square silicon wafer sample
using a lab spin-coater. I'm dispensing about 0.4 ml onto the surface using
a syringe (static dispense). My spread spin is 500 rpm / 5 sec while spin
speed is 4000 rpm/ 30 sec. However, I'm always getting an uneven thickness
(in circular pattern) The centre looks different while sides are in
different color. How do I improve uniformity? Your kind help is highly
appreciated.

Abang Annuar.