Nobody seems to have mentioned electron beam lithography. Hobbyists have done that.[1] E-beam lithography has been used since the 1970s. It's slow; it might ta

Nobody seems to have mentioned electron beam lithography. Hobbyists have done that.[1] E-beam lithography has been used since the 1970s. It's slow; it might take a day to make a CPU. That's why it's not used as a production process. But as a prototype process, it works fine. There are a few hobbyists doing this.[1] E-beam systems are basically scanning electron microscopes with more power. There's a vacuum chamber, means for focusing and steering an electron beam similar to what's inside a CRT, and control equipment. It's all computer-controlled, of course. This has many advantages. Software can correct for nonlinearities in the scanning. The machine can inspect what it's written by scanning at low power. You still have to coat and etch; it's not a dry process. The beam just exposes photoresist. The equipment is the size of a desk. Here's a machine at CMU.[2] Many universities have such machines. [1] https://hackaday.com/2024/08/06/creating-1%c2%b5m-features-the-hacker-way/ https://hackaday.com/2024/08/06/creating-1%c2%b5m-features-t... [2] https://nanofab.ece.cmu.edu/facilities-equipment/fei-sirion.html https://nanofab.ece.cmu.edu/facilities-equipment/fei-sirion....