The problem you have is with the square substrates. We manufacture a coater that
uses a spray technology we developed that allows a fine spray to be controlled
while the wafer is spinning at a low rpm 300 and our dispense arm is
programmable to allow a sweep that spends more time on the edges and speeds up
through the center. This compensates for the difference in surface area to be
coated. Our uniformity from center to edge is around 5% 1 sigma on square
substrates up to 8" x 8". For more information contact Bob Henderson at
480-968-8818 x 11