I am using SU-8 2025 to generate a high aspect ratio microchannel. I made two microchannels with the properties of:
1. width = 10 um.
height = 25 um.
SU - 8 2025.
2. width = 15 um.
height = 37.5 um.
SU - 8 2025.
Problems:
1. After careful soft-lithography, almost all of my channels tear off (silane treatment applied for soft-lithography). I am assuming that there is a problem with the photolithography process although I was following the SU-8 2025 protocol to generate both microchannels. Is there any suggestion to solve this? Any input will help!
2. Based on point 1, somehow the remaining channel has higher height than my target height. How is it possible ?
3. In another try, I was using omnicoat as adhesive promoter and the omnicoat and PR layer tear off after soft lithography.
Any opinion will help, thank you.
Hi,
Answering to question 1:
Have you performed the hard bake after development? This procedure makes the structure more resistent for soft lithography.
Have you tried with an interstitial layer of SU8? this is a first thin layer of SU8 that you flood expose to have better adhesion of your structures.
Question 2:
By changing spinning conditions you can change the height.
Hi, regarding question 1 I have the same opinion as Carolina Rodríguez-Gallo suggested, try with an interstitial thin layer of SU-8. After spin coating the thin layer of su-8 2025, do soft-baking for a short time and then spin coat the other layer with a slightly higher rpm than the one in the recipe.
Regarding the second question, please check the level of the hot plate. Sometimes the hotplate is not properly leveled and the photoresist flows to one side of the wafer making the structure non-uniform.
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