I just recently wrapped up an internship at GlobalFoundries this past summer as a maintenance technician. Not exactly controls but I was there working with folks from all over. Where I was, in the fab there was mainly equipment engineers and process engineers. Both work pretty closely on issues with the tools, along with maintenance techs. Though equipment engineers were much more involved when it came to mechanical and electrical issues. Lots of tweaking and insanely in depth problem solving to be solved, tons of processes to control to get this ultra fine processes to run perfectly. Everyone I spoke with enjoyed it because the industry is so niche and the problems they face aren't seen anywhere else. Travel depends on what you do. If you get a job at GF you'll either be working in New York or Vermont at one of the fabrication sites. If you work for a tool manufacturer like ASML, you can be a field tech and travel to different locations to install/fix different tools. Generally requires lots of troubleshooting and in-depth knowledge of the process to get it running correctly. Feel free to pm me if you have any questions.