I looked at the site and it's cool that that he's not using HF to metal etch. Instead he's using an ammonia and hydrogen peroxide solution. That's a lot safer

I looked at the site and it's cool that that he's not using HF to metal etch. Instead he's using an ammonia and hydrogen peroxide solution. That's a lot safer stuff to handle. That seemed to always be the roadblock to home silicon fabrication: that you needed to use some very toxic stuff to metal etch.