How to SU8
!!!ALWAYS WORK UNDER THE FUME CUPBOARD WHEN HANDLING SU8 AND ITS ASSORTED CHEMICALS!!! (The following instructions are for SU8-100 and can also be applied to SU8-50. Check with microchem for guidelines for other version of SU8)
(1) Put SU8 in a small beaker (~10ml in total)
(2) Heat ~7ml of SU8
(3) Heat up a hot plate @66°C for 10'(until it's runny).
(4) Calculate 1ml/inch (or 1ml/2cm).
(5) Set the spinner.
(6) Do a manual spread: You have 10 to set the spread from 0 to 500rpm.
(7) Set the spin spread @2500rpm for 30 (or adjust spread as required)
(8) Use a glass syringe to spread (2ml volume would be OK). Keep it in aceton until needed.
(9) Measure 1ml of SU8 (slowly because the barrel might run out of travel) and spread it in a spiral motion, so that it covers all the surface of the sample.
(10) Clean the syringe immediately.
(11) Spin coat.
(12) Bake on a hot plate @66°C for 20' and then @95°C for 50'. Make sure hot plate is flat to avoid thickness fluctuations. Let sample cool down to room temperature on hot plate.
(13) Turn on mask aligner.
(14) Develop pattern. Exposure time depends on how old the UV lamp is, so adjust accordingly.
(15) Post exposure bake: 1' @65°C then 12'@95°C. The pattern will start developing by now.
(16) The developer for SU8 is the EC solvent (smells really bad, so keep the sash of the hood as low as possible!)
(17) Wash your photolith mask with aceton.
(18) After the sample has been heated, switch off the hot plate and let the sample cool down SLOWLY on the hot plate.
(19) When cooled at room temperature, it needs to be developed.
- put some developer in a beaker and let the sample in for ~5' while it's agitated.
- stop the procedure with IPA.
- If it's "milky" it means it's underdeveloped and needs to go back in to the developer.