Forum,

I use SPR 220-7 and get a good coat with the following:

Step                    1       2
Dispense                on
Vel     rpm             200     4000
Ramp    r/s             15      2000
Time    sec             14      30

You need to almost cover the wafer with resist at low RPM, then ramp to your
final RPM.

Don't forget to check your cup exhaust.  If high or low you will get a bad
coat.


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-----Original Message-----
From: Shah, Forum N [mailto:forum@exchange.uta.edu]
Sent: Tuesday, July 21, 2009 2:19 PM
To: General MEMS discussion
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