We are experimenting with SU8 2000.5 (0.5 um thick) on GaAs substrates.
Quite often, the part of the resist that has *not* been exposed cannot be removed using SU-8 developer. This issue has persisted over quite a few different variations of prebake and postbake times and temperatures, ranging from those in the Kayaku data sheet to those given in "Processing of thin SU-8 films," J. Micromech. Microeng. 18 125020 (2008), where the authors just used a room-temperature evaporative “prebake” and a 50°C postbake.
I don’t understand how resist that has not been exposed fails to develop, since in these regions its acid has not been activated nor can it presumably become cross linked during postbake.
Does anyone have some insight into how this might happen, and any suggestions of how to fix the problem?
- Badges
- Science topic
- Similar topics
- Physical Sciences
- Materials Science
- Materials Chemistry
- Polymer Chemistry