Exposure times

Sebastian J. Osterfeld sjo at stanford.edu
Tue Apr 15 15:55:25 PDT 2008

Hi Chris,

I had some trouble with SPR220 in the past, basically it exposes 
quickly, but development can take up to 20 minutes!

Generally, slight overexposure is best, especially if you can live with 
slightly rounded edges. I would try:

SPR220-7 @ 15 microns - 30 seconds exposure
SPR220-7 @ 7 microns - 15 seconds exposure
SPR220-3 @ 3 microns - 7 seconds exposure

Best regards,

> Hi All,
> After some experimentation, it turns out that it is the development 
> that is unusual on SPR220-7 (15 microns), not the exposure.
> I used 1 coat of SPR220-7, exposed at 30 seconds. It develops fine, 
> but due to the lack of agitation, it takes a *very* long time on the 
> track - up to 20 minutes (4x the entire 7 micron develop program).  
> This was the step that was difficult to figure out, since from 3612 
> (any thickness) my experience was that anything which doesn't develop 
> within three minutes will not develop at all and is a sign of 
> underexposure.
> Final thickness after hard bake was something like 12 microns.
> Sebastian 

Let me know if this helps,

Chris Earhart wrote:
> Hi everyone,
> Can someone let me know the current recommended exposure times for
> SPR220-3 3 micron and SPR220-7 resists?
> Thanks,
> Chris

Sebastian J. Osterfeld
Ph.D. Candidate, Shan X. Wang Group
Dept. of Materials Science & Engineering
Stanford University

McCullough Building, Room 208A
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