The Zeloof Z2 Intergrated Circuit Has 100 Transistors

Back in 2018 we reported on the first silicon integrated circuit to be produced in a homemade chip fab. It was the work of [Sam Zeloof], and his Z1 chip was a modest six-transistor amplifier. Not one to rest on his laurels, he’s back with another chip, this time the Z2 is a hundred-transistor array. The Z2 occupies about a quarter of the area of the previous chip and uses a 10µm polysilicon gate process as opposed to the Z1’s metal gates. It won’t solve the global chip shortage, but this is a major step forward for anyone interested in building their own semiconductors.

The transistors themselves are FETs, and [Sam] is pleased with their consistency and characteristics. He’s not measured his yield on all samples, but of the twelve chips made he says he has one fully functional chip and a few others with at least 80% functionality. The surprise is that his process is less complex than one might expect, which he attributes to careful selection of a wafer pre-treated with the appropriate oxide layer.

You can see more about the Z2 in the video below the break. Meanwhile, should you wish to learn more about the Z1 you can see [Sam’s] Hackaday Superconference talk on the subject. We’re looking forward to the Z3 when it eventually arrives, with bated breath!

30 thoughts on “The Zeloof Z2 Intergrated Circuit Has 100 Transistors

        1. Think he’s referring to people constantly saying stuff like ‘you could have done that with a 555 timer instead of using a full blown microcontroller/raspberry pie’. I like your interpretation better tho

          1. Then he could make a 3909 LED flasher, which is no longer made. For some uses, better than a 555.

            In 1976, I was given atube of 555s. I still have some. I guess a syatement on how I reuse parts, rather than a dismissal of tIe 555

    1. Right now he made some N-type MOSFET. The only type of logic he could be making is NMOS.

      At some point, he’ll need to be able to make PMOS transistors to make CMOS (as in complementary i.e. P + N transistors). Making PMOS transistors on top of the P well would mean at least 2X the number of steps.

      Circuit complexity would need some routing layers. Think of it as routing a PCB, how many time you would need to add jumpers or go beyond a single layer for anything non-trivial?

      Don’t hold your breath.

      1. Don’t forget his z1 chip used PMOS transistors. NMOS ICs are apparently harder to do and suspect it may now even be possible for him to make an original 6502 CPU (which uses NMOS).

        Going to CMOS is one of his stated future aims in his current blog, so I’ll keep watching this space :-)

    1. I put off watching this vid until I had more time, and now I’ve seen it, all I can say is wow!

      This guy *might* have a lot of time and money, but that’s probably not true. I know a guy that has a mass spectrometer in his garage and works for a pretty measly salary. I’d take a wager he got most of his gear on the cheap by knowing people in the know and being at the right place at the right time.

  1. Amazing work, like small companies launching rockets into space where in the 60s it took a nation state, one dedicated individual is doing now what it took thousands of engineers to do back then. Thanks for sharing this alchemy with the world, demystifying this process.

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