I recommend learning about semiconductor fabrication because it's fascinating. I spent five years as a process engineer in a semiconductor plant, and I saw some really cool technology while I was there. How many other fields use TEM micrographs for debugging? Or make factories with separate foundations for dozens of pieces of equipment, built on piles sunk 60 feet to rest on bedrock? Or have unit processes that include particle accelerators?
However, the chasm between undergrad CS and semiconductor fabrication is too big. There are dozens of layers in between, and all of them are interesting. If you want something more relevant to your degree, study computer architecture or VLSI design. Learn an FPGA synthesis language. If you like quantum mechanics, study semiconductor physics. Learn how a DRAM cell works and why it needs to be refreshed.
At any rate, I don't want to discourage people from studying semiconductor fabrication, but don't do it as part of a CS education. Do it because turning rocks into circuits is an awesome work of alchemy and you can be part of it.