Bravo: Sam Zeloof isn’t your ordinary teenager. While still a senior in high school in 2018, he made the first homemade (lithographically-fabricated) integrated circuit which he dubbed the “Z1.” The chip only had six transistors on it, but again, he made the thing at home in a garage. Now, he’s back with version two.
Appropriately named “Z2,” this new chip packs 100 transistors on a 10µm polysilicon gate process. That’s the same technology that Intel used to create its 4004 CPU way back in the early 1970s, but to directly compare the two would be a bit unfair as Intel’s chip featured 2,300 transistors.
The chip design consists of a simple 10x10 array of transistors that Zeloof was able to lay out in Photoshop. As before, the entire process took place in his “garage fab” using impure chemicals, homemade equipment and without a clean room.
The Z2 is leaps and bounds better than the Z1. Switching to a polysilicon gate process reduced power consumption significantly, but without pure chemicals and in the absence of a clean room, yields are low.
“I’ve made 15 chips (1,500 transistors) and know there’s at least one completely functional chip and at least two “mostly functional”, meaning ~80 percent of the transistors work instead of 100 percent,” Zeloof said.
The most common defect, he said, is a drain or source shorted to the bulk silicon channel. With the Z1, the biggest issue was a leaky or shorted gate.
Thinking back to what I was doing at this age, it’s safe to say that Zeloof is well ahead of the curve. Those interested in supporting his endeavors should check out his newly created Patreon page.