You can try to drop a big dose of the polymer on the substrate and wait till it
flows to cover the entire surface. Then spin.
This could improve the surface coating, but there could also be smaller
striations or ripples.

Dr. Pablo de la Fuente
Optical Development R&D Engineer

FAGOR AUTOMATION S. Coop.
Phone: 943 71 92 00
Fax: 943 71 92 03
e-mail: pdlfuente@fagorautomation.es
web: www.fagorautomation.com


Sandip Agarwal wrote:
> I am trying to spin-coat a polymer (1% PMMA-butadiene copolymer in
> toluene) on a substrate that has topographical features that are 50x50
> micron posts and 10 microns tall. I observe striations or ripples that
> run from the center of the substrate to the periphery after
> spin-coating. Any solutions? I have tried varying the concentration
and
> dynamic dispensing without any success.