Cambridge scientists build 3D spintronics storage chip

Breakthrough could reduce processor footprint and power consumption

Stewart Mitchell
31 Jan 2013

Researchers at the University of Cambridge have built the world's first three-dimensional spintronic microprocessor, with claims that the breakthrough could dramatically reduce power consumption.

Spintronics technology uses the polarity of electrons instead of transistors to process or store data, and is emerging as a building block for future chip designs.

According to lead researcher Russell Cowburn, the new chip architecture could lead to microprocessors with a much lower drain on batteries and chips that perform the same function as current designs in a smaller footprint.

3D chips have been mooted before, but the Cambridge researchers say they have developed a system that actually works, layering different materials on top of each other, and using atoms as staircases between the various layers.

People want small chips because you can fit more into the same footprint, but the other thing is they're much cheaper

"People will have heard about 3D conventional CMOS before, but this is the first time spintronic chips have been made in 3D," said Cowburn.

"People have tried building 3D CMOS and you can do two or three layers, but it's rarely worth it because the cost tends to scale with the number of layers and there are real complexities about how you get the heat out of the middle," he told PC Pro.

"What we've done is show at an atomic level that you can stack these spintronic layers in a way that is scalable so you can keep on just going up and up without very much added cost."

Describing the design as "a club sandwich on a silicon chip of cobalt, platinum and ruthenium atoms," the researchers said the cobalt and platinum atoms store the digital information in a similar way to current hard disks.

"The ruthenium atoms act as messengers, communicating that information between neighbouring layers of cobalt and platinum," the researchers said. "Each of the layers is only a few atoms thick."

According to Cowburn, the technology could be applied to both logic and memory uses, although he said that most spintronic chips currently approaching production are in memory chips, which might make them a more obvious starting place for 3D technology.

Spintronics as a mainstream storage option remains perhaps 18 months away, Cowburn said, adding that “we are still some way behind that”.

Power potential

Nonetheless, the development could lead to significant advances in both performance and cost of manufacturing, not only extending battery life but removing heat from the equation.

"When you think about working in three dimensions you have to be careful you don't make that problem worse - it's easy to make it worse because you have enclosed all the heat in the middle," he said. "The beauty of spintronics chips is they create very little heat themselves."

While shrinking chip sizes has obvious advantages for device designers that are eager to put more performance or storage into a smaller footprint, it also has benefits for chip manufacturers.

"People want small chips because you can fit more into the same footprint, but the other thing is they're much cheaper – the cost of making an entire wafer is fixed, so the more chips you can get from that wafer, the cheaper they appear," Cowburn said. "Either way, this 3D methods allows you to get more kick from the same footprint."

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