Apply resist statically and start by spreading the resist at low rpms (300 -
500).  Once wafer has been covered slowly increase to the desired speed and time
to obtain your thickness.

Phil

> From: forum@exchange.uta.edu
> To: mems-talk@memsnet.org
> Date: Tue, 21 Jul 2009 16:19:05 -0500
> Subject: [mems-talk] SPR 220-7
>
> Hi everyone,
>
> I am using SPR 220-7 photoresist and am looking at 7 micron thickness. I am
spinning at
>3500 rpm for 30 seconds and also tried 3k rpm for 30 seconds..
>
> I see a lot of streaks on the wafer and not getting a uniform coating. I did
take a look at
> Stanford nanofab website (www.snf.edu) but the problem is that I have manual
spinners
> and their manual procedure is also not working fine for me.
>
> If anyone has worked with it before, your suggestions would be invaluable.
>
> Thanks in advance.
> Forum