Making the masks in photoshop is a really neat trick. Reminds me of Bob Moore of Forth fame who said something like "once you have enough code to draw a square you are half way to a chip design package".
Related thread: https://news.ycombinator.com/item?id=28176255
I loved this, it made me realise how close to negative development is to photolithography. When doing separate etching layers how are wafers lined up or is everything done in situ?
Interesting. Curious what the yield is. And he doesn't need a cleanroom, or work with dangerous chemicals like HF?
Direct link to the blogpost: http://sam.zeloof.xyz/second-ic/