Table of Contents:
Alex Mellnik, October 23, 2014
It's possible to get 0.5 um lines with this recipe. The values are optimized for sapphire substrates, and the last bake and the development time may need to be adjusted depending on the substrate.
Resist Recipe for Liftoff or Etching
Spin LOR-3A in the class 2 room for 60 s at 3000 RPM with 1000 RPM/s acceleration.
Bake 5 min at 180 C.
Spin S-1813 for 60 s at 3000 RPM with 1000 RPM/s acceleration.
Bake 1:15 at 115 C for sapphire substrates.
Expose 0.26 seconds in the 5x stepper.
Develop for 1:30 in 726-MIF developer using minimal agitation.
Rinse in DI water.
Suggestions for mounting pieces in the 5x:
Mahmoud Elzouka, July 27, 2015
Lift-off tips:
LOR thickness should be at least 1 to 1.25 times the target thickness of metal to have the liftoff process complete satisfactorily within 12-24 hours. More LOR may speed up the liftoff process.
The LOR undercut is visible in the optical microscope, the edge of the LOR and the edge of the top photoresist is offset bu around 500 nm to a couple um based on process parameters.