When exposed to light sources with certain wavelength: for positive photoresist materials, the exposed parts will be washed off by developer and the rest of the unexposed parts will remain on the substrate; while for negative photoresist materials, the exposed parts will remain on the substrate after developing, while the unexposed parts will be washed off.

So my question is, when I mix any positive and negative photoresist together, what will happen after exposure to light sources and developing? Which parts will be washed off?

  • $\begingroup$ Do you know what chemicals are in your materials ? Especially what the developer is composed of ? Is it just a solvent or is there some chemistry going on ? Is it the same for the positive and negative photoresist ? $\endgroup$
    – SCH
    Sep 1, 2016 at 12:23
  • $\begingroup$ I have S1813(the positive photoresist) and SU8 (the negative photoresist) in my lab. I'm a physics student so not quite sure about the chemical structures of my materials. They both have their own developers, not the same. I'm just curious if I mix them, will their positive and negative photoresist abilities cancel out... $\endgroup$
    – Xiaoxi Man
    Sep 1, 2016 at 12:56
  • $\begingroup$ Also posted to Physics SE. $\endgroup$
    – Jon Custer
    Sep 1, 2016 at 13:13
  • $\begingroup$ Crosssposted to physics.stackexchange.com/q/277619/2451 $\endgroup$
    – Qmechanic
    Sep 1, 2016 at 14:14

1 Answer 1


Without knowing what the positive developer does to the negative photoresist and vice versa, I can only guess.

Assuming the developers are just washing agents, then the positive photoresist will stay on the unexposed parts, and the negative photoresist will stay on the exposed parts. So you would get an entirely covered substrate.

Why not try the experiment you are proposing in your lab, and tell us the results? That would be neat.


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