This 22-year-old builds chips in his parents’ garage

Zeloof spins hand-cut half-inch squares of polysilicon at 4,000 revolutions per minute on a small homemade turntable, each one becoming an individual chip, and coating it with the necessary layers to transfer his designs to the surface. photosensitive material. Then his homemade lithography machine shined on his design: a grid of 12 circuits, each with 100 transistors (and a dancing bear), for a total of 1,200 transistors.

Each chip is then etched with acid and cooked in a furnace at about 1,000 degrees Celsius to bake the phosphorus atoms to adjust their conductivity. Three more rounds under the lithography machine — separated by steps, include time in a vacuum chamber filled with glowing purple plasma to etch away the polysilicon — to complete each chip. Today’s commercial fabs produce chips in roughly a similar fashion, using a series of steps to gradually add and remove material from different parts of the design. These chips are far more complex, with billions of much smaller transistors tightly packed together, and these steps are done by machines rather than by hand. The transistors on Zeloof’s second-generation chips are about 10 times faster than those on his first-generation chips, and have properties as small as 10 microns, not much bigger than a red blood cell.

In August, Zeloof tested the Z2 connected to a square beige semiconductor analyzer released by HP some 20 years before he was born. Success is marked by a series of smoothly rising current-voltage curves on its glowing green screen. “The curve is amazing,” Zeloof said. “It’s the first sign of life after you’ve dipped this little crystal fragment into a beaker of chemicals all day.”

How to celebrate when your homemade chips work? “Tweet it!Zeloff said. His project has garnered dedicated Twitter followers and millions of YouTube views, as well as some practical tips from semiconductor industry veterans in the 1970s.

Zeloof said he’s not sure what he wants to do after graduation this spring, but he’s been thinking about DIY chipmaking’s place in the modern tech ecosystem.In many ways, DIY experimentation has never been more powerful: robotic devices and 3D printers are readily available, while hacker-friendly hardware such as Arduino microcontrollers and raspberry pie Well established. “But these chips are still made in a big factory somewhere,” Zeloof said. “Little progress has been made in making it more accessible.”

Ellsworth’s homemade transistor inspired Zeloof, who says enabling high-quality hands-on chip manufacturing could be valuable. “The tools we have today can put small-scale operations at our fingertips, and for some issues, I think that makes sense,” she said. For leading fabs, chip technology deemed outdated is still useful to engineers, Ellsworth said.

Zeloof has recently upgraded his lithography machine to print details as small as about 0.3 microns or 300 nanometers, roughly on par with the commercial chip industry in the mid-90s. Now, he’s thinking about what he could build into Intel’s historic 4004-scale chip. “I want to push the garage silicon further and open up people to the possibility that we can do these things at home,” he said.

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