Awesome video and process, we've been talking about this at work since it showed up here and have a few questions if you don't mind:
How far do you think you'd be from making a simple 8-bit CPU like a 6502?
Have you thought about illuminating the initial film exposure as well as the substrate exposure (on the slide glass) using monochromatic light sources like a mercury UV lamp?
Instead of a vacuum pump to flatten the film during exposure, how about electrostatic charges?
Thanks! I'm very far from making a CPU. Check out Sam Zeloof's work to see some of the other parts of home IC fabrication. Creating the mask is just one part of the process, and dialing in diffusion, oxide growth, metal deposition would take a lot of additional effort.
Yes. My original attempt (years ago) was to use a standard photographic enlarger: replace the lens with quartz, place the paper or plastic master design on a UV light source on the table, then place the microscope slide with photoresist in the enlarger where the film would normally go. One problem is the lens is not setup to cover a whole microscope slide. Another problem is not enough UV light getting through the whole optical system -- exposure would have been hours if it worked at all.
Haven't tried electrostatic. Considered low-tack adhesive (3M post-it).
I looked up the 4004 earlier today, thinking about DIY microprocessors. It was 10 micron process. 20 micron is more like 1960-level technology, unfortunately.
As a member of Foulab, home of Thought Emporium, and as an avid watcher of many channels (yours, Thought Emporium, RedNile, BlueNile, etc) which you contributed ideas, knowledge or/and hardware over the years: thank you for spreading such tech around the hackspaces, youtube and homelab community! The content you inspired, made or indirectly contributed to is what makes YouTube the such an amazing platform.
I love your passion and drive towards making things work. Often without a blueprint to follow. Thanks for shining light (sometimes literally) on so many obscure topics.
If you ever find yourself bored, we could really use a reliable method of removing a camera senor bayer matrix. Bonus points if you can figure out how to deposit microlenses back onto the photosites after removal.
Did you ever get the low temp vantablack working as expected? I’m guessing oxygen is passivating the aluminum surface somewhere in the process, and the paper doesn’t document how careful they were. I’d personally want to do this under a nitrogen atmosphere, but I’ve never sonicated under a controlled atmosphere.
I’d bet the reason you can sort of get aluminum to blacken over the heated beaker has something to do either with the fact that the beaker is effectively positive pressure and pushing out everything but water vapor, or that the condensed watervapor on the surface of the aluminum is consistently oxygen free.
I find the former somewhat less believable than the latter, but it’s been a while since I’ve worked on things like this.
If you used your microscope slide as a mask to do photolithography on silicon, you'd use an optical reducer, right? So the feature size on the silicon could be ~5x smaller?
I believe current tech uses 4x reduction from masks down to actual chips. This works well with sizes needed for quartz lens systems, etc. Older processes used 1x reduction (either direct contact, or very tiny offset). This is cheaper and easier because you don't need any quartz lenses, which are needed instead of standard glass for their UV transmission ability.
Interesting. I've got a 180nm mask from a previous job. It's obviously a larger scale than the finished chip. Could be 4x. I think it is from TSCM, circa 2003, for mixed signal CMOS.
