Is Success in Miniaturization its Own Worst Enemy?
Nowadays two transistors, fabricated a few dozen nanometers apart on the same piece of silicon, will not have the same electrical properties.
It’s one of the key barriers that the global chip industry—with sales of US $300 billion—must overcome to keep producing better, faster, cheaper, more energy-efficient chips. The culprit is scaling.
Chips have improved because their transistors and connecting wires have kept getting smaller, but now they’re so small that random differences in the placement of an atom can have a big impact on electrical properties. Some batches vary so much that more than half will run 30 percent slower than intended or consume 10 times as much power as they should when on standby.
Some of these defective chips can be sold at a discount, but if they’re for application-specific designs—say, for mobile phone communication or video encoding—they might find no better destination than the junkyard. And the defect rate will only get worse as transistors continue to shrink.
(via The Threat of Semiconductor Variability - IEEE Spectrum)