Superconference Interview: Sam Zeloof

In less than four days, the fifth Hackaday Superconference kicks off in Pasadena, California, and it’s shaping up to be a hoot. With a cavalcade of exciting workshops and talks on offer, hackers and makers are pouring in from across the globe for this celebration of software, firmware, and hardware.

Of course, the real gift of Supercon is the personalities which make up this awesome community. [Sam Zeloof] is one such luminary, well known for producing his very own silicon integrated circuits in his parent’s garage. Not content to keep this knowledge to himself, [Sam] gave an amazing talk at the 2018 Supercon on just what goes into creating your own silicon fab on a budget.

Our very own [Mike Szczys] caught up with [Sam] for an interview, discussing being inspired by the work of [Jeri Ellsworth], as well as the finer points of getting into lithography at home. [Sam] will be in attendance at the 2019 Superconference, of course. While he won’t be on the speaking circuit this year, his brother [Adam] will be presenting a talk called Thermodynamics for Electrical Engineers: Why Did My Board Melt (And How Can I Prevent It)?, which is sure to be a must-see.

You really should be there, but alas tickets have been sold out for almost two months! Never fear, we’ll be livestreaming the event. Be sure to subscribe to Hackaday on Youtube to be notified when it all kicks off, around 10 AM Pacific Time on Saturday, November 16th. If you scored tickets and are heading to Supercon, we can’t wait to see you there — the badge hacking begins early Friday morning.

Be sure to check out Sam’s interview after the break!

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Of Roach Killer And Rust Remover: Sam Zeloof’s Garage-Made Chips

A normal life in hacking, if there is such a thing, seems to follow a predictable trajectory, at least in terms of the physical space it occupies. We generally start small, working on a few simple projects on the kitchen table, or if we start young enough, perhaps on a desk in our childhood bedroom. Time passes, our skills increase, and with them the need for space. Soon we’re claiming an unused room or a corner of the basement. Skills build on skills, gear accumulates, and before you know it, the garage is no longer a place for cars but a place for pushing back the darkness of our own ignorance and expanding our horizons into parts unknown.

It appears that Sam Zeloof’s annexation of the family garage occurred fairly early in life, and to a level that’s hard to comprehend. Sam seems to have caught the hacking bug early, and by the time high school rolled around, he was building out a remarkably well-equipped semiconductor fabrication lab at home. Sam has been posting his progress regularly on his own blog and on Twitter, and he dropped by the 2018 Superconference to give everyone a lesson on semiconductor physics and how he became the first hobbyist to produce an integrated circuit using lithographic processes.

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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!

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Start Your Semiconductor Fab With This DIY Tube Furnace

Most of us are content to get our semiconductors from the usual sources, happily abstracting away the complexity locked within those little epoxy blobs. But eventually, you might get the itch to roll your own semiconductors, in which case you’ll need to start gearing up. And one of the first tools you’ll need is likely to be something like this DIY tube furnace.

For the uninitiated, [ProjectsInFlight] helpfully explains in the video below just what a tube furnace is and why you’d need one to start working with semiconductors. Perhaps unsurprisingly, a tube furnace is just a tube that gets really, really hot — like 1,200° C. In addition to the extreme heat, commercial furnaces are often set up to seal off the ends of the tube to create specific conditions within, such as an inert gas atmosphere or even a vacuum. The combination of heat and atmospheric control allows the budding fabricator to transform silicon wafers using chemical and physical processes.

[ProjectsInFlight]’s tube furnace started with a length of heat-resistant quartz glass tubing and a small tub of sodium silicate refractory cement, from the plumbing section of any home store. The tube was given a thin coat of cement and dried in a low oven before wrapping it with nichrome wire. The wrapped tube got another, thicker layer of silicate cement and an insulating wrap of alumina ceramic wool before applying power to cure everything at 1,000° C. The cured tube then went into a custom-built sheet steel enclosure with plenty of extra insulation, along with an Arduino and a solid-state relay to control the furnace. The video below concludes with testing the furnace by growing a silicon dioxide coating on a scrap of silicon wafer. This was helped along by the injection of a few whisps of water vapor while ramping the furnace temperature up, and the results are easily visible.

[ProjectsInFlight] still needs to add seals to the tube to control the atmosphere in there, an upgrade we’ll be on the lookout for. It’s already a great start, although it might take a while to catch up to our friend [Sam Zeloof].

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A wafer being loaded into an electron microscope

Using Electron Beams To Draw Tiny Shapes Onto Silicon

Over the past few years we’ve seen several impressive projects where people try to manufacture integrated circuits using hobbyist tools. One of the most complex parts of this process is lithography: the step in which shapes are drawn onto a silicon wafer. There are several ways to do this, all of them rather complicated, but [Zachary Tong] over at Breaking Taps has managed to make one of them work quite well. He shares the results of his electron-beam lithography experiments in his latest video (embedded below).

In e-beam lithography, or EBL, shapes are drawn onto a wafer using an electron beam in a vacuum chamber. This is a slow process compared to optical lithography, as used in mass production, but it is reasonably simple and very flexible. [Zach] decided to use his electron microscope as an e-beam litho machine; although not designed for lithography, it has the same basic components as a real EBL machine and can act as a substitute with a bit of software tweaking.

An AFM image of Rick Astley
[Zach] also has an atomic force microscope, which he used to make these beautiful images.
The first step is to coat a wafer with a layer of e-beam resist. [Zach] used PMMA, commonly known as acrylic plastic, and applied it using spin coating after dissolving it in anisole. He then placed the wafer into the electron microscope and used it to scan an image. The image was then developed by rinsing the wafer in cold isopropyl alcohol.

[Zach] explains the whole process in detail in his video, including how he tuned all the parameters like resist thickness, beam strength, exposure time and development time, as well as the software tricks needed to persuade the microscope to function as a litho machine. In his best runs he managed to draw lines with a width of about 100 nanometers, which is seriously impressive for such a relatively simple setup.

These e-beam lithography experiments follow on from [Zach]’s earlier research using lasers. Homebrew IC expert Sam Zeloof has also used electron beams in his work. Thanks for the tip, [smellsofbikes]!

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Integrated Circuit Manufacturing At Bell Labs In 1983

With the never ending march of technological progress, arguably the most complex technologies become so close to magic as to be impenetrable to those outside the industry in which they operate. We’ve seen walkthrough video snapshots of just a small part of the operation of modern semiconductor fabs, but let’s face it, everything you see is pretty guarded, hidden away inside large sealed boxes for environmental control reasons, among others, and it’s hard to really see what’s going on inside.

Let’s step back in time a few decades to 1983, with an interesting tour of the IC manufacturing facility at Bell Labs at Murray Hill (video, embedded below) and you can get a bit more of an idea of how the process works, albeit at a time when chips hosted mere tens of thousands of active devices, compared with the countless billions of today. This fab operates on three inch wafers, producing about 100 die each, with every one handled and processed by hand whereas modern wafers are much bigger, die often much smaller with the total die per wafer in the thousands and are never handled by a filthy human.

Particle counts of 100 per cubic foot might seem laughable by modern standards, but device geometries back then were comparatively large and the defect rate due to it was not so serious. We did chuckle somewhat seeing the operator staff all climb into their protective over suits, but open-faced with beards-a-plenty poking out into the breeze. Quite simply, full-on bunny suits were simply not necessary. Anyway, whilst the over suits were mostly for the environment, we did spot the occasional shot of an operator wearing some proper protective face shielding when performing some of the higher risk tasks, such as wafer cleaning, after all as the narrator says “these acids are strong enough to eat through the skin” and that would certainly ruin your afternoon.

No story about integrated circuit processing would be complete without mentioning the progress of [Sam Zeloof] and his DIY approach to making chips, and whilst he’s only managing device counts in the hundreds, this can only improve given time.

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Hackaday Links: January 23, 2022

When Tonga’s Hunga-Tonga Hunga-Ha’apai volcano erupted on January 15, one hacker in the UK knew just what to do. Sandy Macdonald from York quickly cobbled together a Raspberry Pi and a pressure/humidity sensor board and added a little code to create a recording barometer. The idea was to see if the shock wave from the eruption would be detectable over 16,000 km away — and surprise, surprise, it was! It took more than 14 hours to reach Sandy’s impromptu recording station, but the data clearly show a rapid pulse of increasing pressure as the shockwave approached, and a decreased pressure as it passed. What’s more, the shock wave that traveled the “other way” around the planet was detectable too, about seven hours after the first event. In fact, data gathered through the 19th clearly show three full passes of the shockwaves. We just find this fascinating, and applaud Sandy for the presence of mind to throw this together when news of the eruption came out.

Good news for professional astronomers and others with eyes turned skyward — it seems like the ever-expanding Starlink satellite constellation isn’t going to kill ground-based observation. At least that’s the conclusion of a team using the Zwicky Transient Facility (ZTF) at the Palomar Observatory outside San Diego. ZTF is designed to catalog anything that blinks, flashes, or explodes in the night sky, making it perfect to detect the streaks from the 1,800-odd Starlink satellites currently in orbit. They analyzed the number of satellite transients captured in ZTF images, and found that fully 20 percent of images show streaks now, as opposed to 0.5 percent back in 2019 when the constellation was much smaller. They conclude that at the 10,000 satellite full build-out, essentially every ZTF image will have a streak in it, but since the artifacts are tiny and well-characterized, they really won’t hinder the science to any appreciable degree.

Speaking of space, we finally have a bit of insight into the causes of space anemia. The 10% to 12% decrease in red blood cells in astronauts during their first ten days in space has been well known since the dawn of the Space Age, but the causes had never really been clear. It was assumed that the anemia was a result of the shifting of fluids in microgravity, but nobody really knew for sure until doing a six-month study on fourteen ISS astronauts. They used exhaled carbon monoxide as a proxy for the destruction of red blood cells (RBCs) — one molecule of CO is liberated for each hemoglobin molecule that’s destroyed — and found that the destruction of RBCs is a primary effect of being in space. Luckily, there appears to be a limit to how many RBCs are lost in space, so the astronauts didn’t suffer from complications of severe anemia while in space. Once they came back to gravity, the anemia reversed, albeit slowly and with up to a year of measurable changes to their blood.

From the “Better Late Than Never” department, we see that this week that Wired finally featured Hackaday Superfriend Sam Zeloof and his homemade integrated circuits. We’re glad to see Sam get coverage — the story was also picked up by Ars Technica — but it’s clear that nobody at either outfit reads Hackaday, since we’ve been featuring Sam since we first heard about his garage fab in 2017. That was back when Sam was still “just” making transistors; since then, we’ve featured some of his lab upgrades, watched him delve into electron beam lithography, and broke the story on his first legit integrated circuit. Along the way, we managed to coax him out to Supercon in 2019 where he gave both a talk and an interview.

And finally, if you’re in the mood for a contest, why not check out WIZNet’s Ethernet HAT contest? The idea is to explore what a Raspberry Pi Pico with Ethernet attached is good for. WIZNet has two flavors of board: one is an Ethernet HAT for the Pico, while the other is as RP2040 with built-in Ethernet. The good news is, if you submit an idea, they’ll send you a board for free. We love it when someone from the Hackaday community wins a contest, so if you enter, be sure to let us know. And hurry — submissions close January 31.