Zeloof spun hand-cut, half-inch squares of polysilicon, each to become a separate chip, on a small homemade turntable at 4,000 revolutions per minute to coat them with the photosensitive material needed to transfer his design onto the surface. Then his homemade photolithography machine beamed on his design: a grid of 12 circuits, each with 100 transistors (and a dancing bear), 1,200 transistors in all.
Each chip was then etched with acid and cooked in a furnace at about 1,000 degrees Celsius to bake in phosphorus atoms to adjust its conductivity. Three more rounds under the photolithography machine—separated by steps including time in a vacuum chamber filled with glowing purple plasma
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