Thin SU-8 Film Lithography - Curing Images
SU-8 is an epoxy based photoresist.
Experimental Procedure
Wafer Preparation
Clean Wafer Dehydration Bake Wafer
Spin Coat
Cover the Solitec spinner's drain and plastic top with a cleanroom wipe. Mount the wafer on the Solitec spinner. Apply a quarter sized puddle of SU-8 to wafer. Ramp to 500 rpm at 100rpm/s (5 seconds) Ramp to 6500 rpm at 300rpm/s (20 seconds). Hold at 6500 rpm for 40 seconds
Softbake
Heat the Cole-Parmer hotplate to 65°C Place the wafer on the hotplate Set the timer to 2 minutes When the time is up change the temperature to 95°C Set the timer to 5 minutes When the time is up transfer the wafer to a wafer holder
Exposure
On the Karl Suss aligner expose the wafer for 12 seconds.
Post Exposure Bake
Heat the Cole-Parmer hotplate to 65°C Place the wafer on the hotplate Set the timer to 1 minute When the time is up change the temperature to 95°C Set the timer to 2 minutes When the time is up transfer the wafer to a wafer holder
Development
Place some SU-8 developer in a glass plate Place the wafer in the developer for 2 minutes The development is very sensitive to the concentration of the developer. After developing a few wafers the development time might need to be increased or new developer should be used.
Curing
Heat the clean oven to 65°C Place the wafer in a metal wafer carrier Place the metal carrier in the oven Set the clean oven to 200°C. This will cause the temperature to ramp up as fast as possible. Set a clean room timer to 30 minutes When the time is up remove the metal carrier from the oven
Results
Channel Width (um) x Separation (um) | Cured | Not Cured |
2x2 | ![]() | ![]() |
2x8 | ![]() | ![]() |
4x4 | ![]() | ![]() |
4x32 | ![]() | ![]() |