Stacking Semiconductor Transistors Could Help Circumvent Moore’s Law
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As chipmakers make their products ever smaller, they run into limits on how much computing power can be packed into a single chip. A record-breaking chip avoided the problem and could lead to more sustainable manufacturing of electronic devices.
Since the 1960s, making electronics more powerful has meant making its building blocks – transistors – smaller and more densely packed on chips. This trend has been illustrated by Moore’s Law, which suggests that the number of components on a microchip will double every year. But that law began to weaken around 2010. Xiaohang Li, of King Abdullah University of Science and Technology in Saudi Arabia, and his colleagues showed that instead of going smaller, the solution to this conundrum might be to build upwards.
They designed a chip made up of 41 vertical layers of two different types of semiconductors separated by insulating material – a stack of transistors about 10 times taller than anything that had been made before. To test its functionality, the team made 600 copies, all of which had similar, reliable performance, and used some of these stacked chips to implement a few different basic operations that computers or sensing devices need. The tokens work similarly to some more traditional tokens that are not stacked.
Li says making these batteries required fewer power-intensive methods than making more standard chips. Team member Thomas Anthopoulos of the University of Manchester in the United Kingdom says the new chip won’t necessarily lead to new supercomputers, but if it could be used in common devices like smart home electronics and wearable health devices, it would reduce the electronics industry’s carbon footprint while providing more functionality with each added layer.
How far could the pile go? “There’s really no stopping. We can keep going. It’s just a matter of sweat and tears,” says Anthopoulos.
But technical challenges remain in terms of the chip’s maximum temperature before malfunctioning, says Muhammad Alam of Purdue University in Indiana. It’s a bit like trying to stay cool by wearing several parkas at once, because each layer adds warmth, he says. The chip’s current thermal limit of 50°C would need to be increased by 30 degrees or more to make it practical for use outside the lab, Alam says. Yet, according to him, the only way for electronics to progress in the short term is precisely to adopt this approach and develop vertically.
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