Hi, Zeng,

I had the same problem (cracks on PR) before. Even though I do not why you
need deposit PR on PDMS (I used Sylgard 184, Dow Corning), I would like to
suggest the following solutions for you consideration.

(1) You can deposit a thin Al (~800A or less) on top of PDMS, and use Al as a
masking layer.

(2) For my own experience, you might want to try the photopatternable-silicone
(Wl-5000, Dow Corning). There are much easier to process. I had a paper for u
reference.
http://www.lehigh.edu/~wez6/LEHIGH_EUROSENSORS_ESCW.pdf

Anyway, 3-5 um is very challenged for either solution.

Good luck!

Lydia











Quoting Hongjun-ECE :

> I'm trying to pattern photoresist on the PDMS but got the following
> problems. Can you guys kindly help me fix them?
>
> 1. I spined PR1818 on the PDMS but found there are a lot of thin cracks in
> the photoresist after the softbake. I guess it is caused by the difference
> of thermal coefficients between the photoresist and the PDMS. Did you guys
> have this problem and how did you resolve it?
>
> 2. I want to pattern photoresist on PDMS with a feature size of 3-5um, do
> you think it is possible? I plasma-treated the PDMS before coating
> photoresist and it seems the adhesion of the resist on the PDMS is very
> good, but when the exposed wafers are developed, all the lines with width
> less than 10um flaked off the PDMS substrate.
>
> Thanks you very much for you help,
>
> Hongjun Zeng, PhD
>
> Microfabrication Application Laboratory (MAL)
> University of Illinois at Chicago
> 3014 ERF Building, 842 W. Taylor Street
> Chicago, IL 60607
> Tel. 312-413-5889, Fax: 312-996-6465
>
>
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