Gear

Intel Lakefield Brings Its 3D Chip-Stacking Tech to Life

Weeks after introducing Foveros, its 3D logic stacking technology, Intel has shown off a motherboard that puts it to use.
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Three years ago, Intel engineer Wilfred Gomes and his colleagues sat down to decide how the future should look.

The team had just finished its work on Intel's next-generation high-performance and low-power processes, both of which would further shrink the company's chip designs to new extremes. But the traditional route of making chips ever smaller had begun to offer diminished gains. Keeping pace with Moore's law would require more dramatic measures. "We were thinking out into the next decade," says Gomes, a 22-year Intel veteran. "How should products be built?"

Intel

They landed on what would become Foveros, a 3D packaging technology that stacks logic chips atop one another. Monday at CES, that design became an actual product: Lakefield, a breakthrough CPU architecture tailor-made for devices that don't yet exist.

From Foveros to Lakefield

Ideas don't become products overnight. It wouldn't be until the following year that Gomes, along with senior fellows Rajesh Kumar and Mark Bohr, brought their proposal to recently hired Intel president Murthy Renduchintala. If the team could pull it off, Renduchintala told them, they could change the direction of the company.

That might sound overstated. But the stakes now are even higher than they were two years ago. Intel's efforts to manufacture chips on the smaller, next-generation 10nm process has fallen behind schedule, cracking open a window for competitors like AMD. "Their credibility is on the line," says Patrick Moorhead, founder of Moor Insights & Strategy.

And while the 3D stacking technique that defines Foveros has been accomplished previously in research labs and in memory chips, no one had come anywhere near producing at scale. The ability to build a chip up rather than out has manifold benefits, chief among them the ability to mix and match transistors for specialized tasks. CPUs destined for gaming laptops have different needs than those that prioritize on interconnectivity. Foveros allows for that customization without sacrificing performance or space. But with those benefits come challenges. Big ones.

"When we penciled it out, we spent a lot of time arguing among ourselves which elements were highly risky and which ones we had to get right" Gomes says. "Typically what we do is pick two or three miracles that we have to somehow pull off."

In this case, it required three. First, the architecture itself, a radical rethinking of how processors look and act. Next, the ability to execute against that stacked design in a way that ensures every part works; if any single layer of the stack fails, your yield drops. And last, heat travels up, a thermal problem that needs to be solved to make a vertical CPU workable.

Intel has offered a glimpse at how it overcame those challenges in Lakefield, if not the whole picture. Every part of the stack gets vetted before assembly, for instance, to weed out any bad silicon before it can cause problems. And the company invented an entirely new insulation material to help dissipate heat.

"If you put the right silicon materials, put the right amount of thermal compounds, and then you design your actual thing so that you don't end up in a thermal hot spot, you should be able to build many compelling 3D stacked products," Gomes says. "Lakefield is the first one."

Specifically, the compute elements of Lakefield are built on Intel's next-generation 10nm process and stacked atop a 22nm chipset. The entire package is a mere 12 x 12 x 1 millimeters; smaller than a dime. If those numbers and nodes trip you up, just know that Lakefield is very small and should be very capable.

"This is the world's smallest PC motherboard ever," says Gregory Bryant, manager of Intel's Client Computing Group, referring the Lakefield-powered product the company showed off Monday.

Just how capable the platform will be remains a mystery. While Lakefield combines a next-generation 10nm Sunny Cove core with four low-power Atom cores, neither Gomes nor Bryant provided specific performance benchmarks, or even a ballpark. "It's hard to compare it to something easily, because the hybrid architecture is totally new," Bryant says.

A New Breed

Still, you can catch glimpses in Lakefield's full potential in how Intel describes the devices it will enable. Here's a hint: They don't exist yet.

"This enables essentially whole new categories of devices to be built," Bryant says. "It speaks to the dynamic range of scaling down to very low power and then up to a more full PC experience, in that tiny little board."

Start with portable PCs or two-in-one form factors, with screens smaller than 11 inches. Then get a little more creative: foldable smartphones or dual-screen devices. Then think of the possibilities that exist beyond the limits of your imagination. That's where Lakefield is headed.

For its part, Intel has gotten Lakefield working on two reference systems: a single-screen device and a dual-screen clamshell. "We had to go that far just to make sure that we were getting the design right," Bryant says.

Companies have attempted unconventional products like this for years, with limited success. It'll take more than innovative CPU architecture for them to take off with consumers. Foldable phones, like the ones Samsung and Royole recently introduced, require breakthrough display materials first and foremost.

Which is to say that with Lakefield, Intel has created a critical piece to a puzzle of uncertain shape and size. Don't take that as a demerit. Whenever the next generation of hybrid devices materializes, they now have a CPU befitting of their needs.

Remember, too, that Intel's long-term ambitions don't rest entirely on Lakefield. That long-awaited 10nm client processor, called Ice Lake, finally got the full demo treatment on Monday, with product shipments expected in time for the next holiday season. Intel also showed off Nervana, a neural network processor for inference that will help it remain competitive on artificial intelligence. And it continues to command nearly 99 percent of the server CPU market.

"Intel's more diversified than I've ever seen them before," Moorhead says.

So take Lakefield for the impressive piece of engineering that it is, but just one of several paths forward for Intel—and even for Foveros itself.

"We did not create Foveros just to say that we were going to build some low-powered product that was going to a niche segment," Gomes says. "We thought about this long and hard, how to architect it from the ground up. Lakefield is the first product of many."

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