The ‘micro’ enterprise that is chip repair
Rodrigo Alvarez can’t afford to replace the defective microprocessors on which his PhD depends, and so he’s learning to fix them himself.
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Rodrigo Alvarez sits silent in a darkened room. He stares through his computer screen at a gray landscape, faintly rippled like windblown sand.
Mr. Alvarez, a PhD student here at Stanford University, is looking at the polished surface of a silicon chip magnified 15,000 times under an electron microscope. That chip sits a few feet away, sealed inside a Frankensteinesque machine with wires protruding from all sides.
Alvarez is at Stanford’s Focused Ion Beam Laboratory, about to do a microscopic repair. It’s the equivalent of cutting and reconnecting wires in a toaster oven 1/100th the size of a grain of sand. Earning his PhD depends on it.
Silicon chips sit at the heart of all things electronic, from computers to iPods to cellphones. But this chip – Alvarez’s PhD project – represents an entirely new vision. He’s designed it to mimic a part of the human brain called the cerebellum. This chip, he hopes, will someday allow intelligent robots to move gracefully to explore Mars, rescue kittens from burning buildings, or cook omelets.
But that’s all in the future. Today, he has a repair job to do. Alvarez has found a fatal flaw in this chip that he spent two years designing.
Two million transistors crowd onto this silicon wafer the size of the nail on your pinkie. They are connected by 250 feet of microscopic wires, which crisscross over one another in six layers, like the stacks of an endless freeway interchange. Among those millions of wires, Alvarez has discovered eight misrouted wires that cause the entire chip to lock up like a crashed computer.
He can’t afford to order a new set of chips from the factory – not at $35,000 a set. So he’ll fix them by hand.
He’ll burn his way down to those offending wires, through the upper layers of the chip, using a high-energy ion beam as a microscopic blowtorch. He’ll cut and weld the tiny wires – without, he hopes, nicking any others.
It’s 10 o’clock on a Thursday morning. Alvarez glances at the corner of the chip displayed on his computer screen. Starting from this reference point, he turns a knob and the image on the screen shifts sideways. He maneuvers to the place where he’ll cut, as though counting paces to a buried treasure, each step measured in millionths of a foot: 400 steps to the right, 150 steps down. Dig here.
He clicks the computer mouse to highlight a rectangle much smaller than the smallest speck of dust visible to a human eye – the spot where he’ll cut.
He clicks a button. A low whir comes from the Gothic horror machine. Inside, a beam of positively charged gallium atoms, traveling at 650,000 miles per hour, sears into the chip.
You might call Alvarez a geek cog in the machine of high-tech innovation – or better yet, a Renaissance man in training.
By designing an entire chip by himself and then repairing it to boot, he’s learning the jobs that 10 different specialists would do at a big company like Intel. That training is meant to produce people who will come up with tomorrow’s big ideas.
“In a startup company you’re going to have the same guy doing everything,” says Stanford professor Kwabena Boahen – Alvarez’s PhD adviser. “That’s what it takes to innovate. Inventions don’t come from teams.”
The version of the chip that Alvarez is repairing today is strictly a research tool for deciphering how the cerebellum works. Some later version of it could find its way into battlefield robots or unmanned submarines, with patents that could net millions of dollars. But all of that is far away. The hard work comes now”
By 2 p.m. Alvarez has made 15 cuts with the ion beam, burning gradually deeper into the chip. He speaks hardly at all.