As per the Microchem data sheet "for applications where imaged resist is to be left as part of the final device, a hard bake can be incorporated into the process if the final device or part is to be subjected to thermal processing during regular operation. A hard bake of 10oC higher than the maximum expected device operating temperature is recommended. A bake temperature in the range of 150oC to 250oC and for a time between 5 and 30 minutes is typically used."
So my query is regarding the right procedure for SU-8 hard bake. Can the imaged resist be directly placed on a hot plate at 250oC for hard bake or starting from room temperature the temperature is to be slowly increased in steps to 250.
Best baking procedure for photoresists are using convectional oven. Specially in SU-8 the ramp up backing is required e.g. to reach the temp. 120C , set the initial temperature to 60C and than ramp up with step of 5C upto 120C.
For hard bake at 250C , the same procedure can be followed.
You can check the attached publication of my group.
You can find the required details on the MicroChem web page (www.microchem.com). Just download the appropriate PDF!
Thanks Dr. Laszek. I have gone through the same and in my query i have quoted some lines from the same but it does not clearly mention regarding the exact procedure for it. i.e Hot plate/oven bake and should the temperature be increased slowly to desired temperature or directly
As SU-8 is highly networked and functionally rich, baking at too high a temperature will set the polymer before all the epoxy can crosslink. As mentioned above, it's best to cure the film at lower temperature, for a long time (think slow-cooking), to allow as many of the epoxy functions to react before setting occurs. Hope this helps.
Just to add to the other good comments, MicroChem advise using a hard bake temperature 10 oC above the maximum expected operating temperature. The hard bake can also be useful for annealing any surface cracks that may have appeared.
There is a specific document issued by MicroChem regarding the hard bake process, I have attached it in case it is of interest to anyone.
- Badges
- Science topic
- Similar topics
- Engineering
- Materials Engineering