Pile them up high!
Intel is making good progress on its next-generation chips. At CES 2019, the chipmaker showed off the first completed designs for Lakefleld, a stacked processor based on its Foveros 3D-stacking design that it revealed last year.
Lakefleld combines a 10nm Sunny Cove core with four lowpower Atom cores, and it sits on what is the world’s smallest PC motherboard, according to Intel. Lakefleld’s compute elements sit atop a 22nm chipset, and the entire package measures just 12 x 12mm.
MIX-AND-MATCH
Chipmakers already stack memory chips on top of one another, but this is the first time 3D stacking is coming to logic-on-logic integration, complete with plans to produce it at scale. It can be thought of as a follow-up to Intel’s existing Embedded Multi-die Interconnect Bridge (EMIB) design, which is currently in use on the Kaby Lake-G processors that contain an Intel CPU, AMD GPU, and HBM2 memory on the same package.
However, while EMIB allows for 2D integration of components built on separate processes, and the key difference is that Foveros adds a new level of density and builds up. Ultimately, Foveros will also involve mixing and matching different “chiplets”, where the core processor components are distributed between different dies. This means you could have your processor cores built on the 10nm process, while things like integrated USB, Wi-Fi, Ethernet, or PCIe could use less cuttingedge 14nm or 22nm processes.
BETTER POWER EFFICIENCY
Power usage would also be a lot lower than if you used the same process across the board. This is because certain components like Wi-Fi or cellular connectivity are optimized on a particular process. Similarly, the best process for a desktop gaming CPU might not necessarily be the same as that for a GPU. Before this, Intel had to settle for the best compromise for all the silicon, but the added flexibility afforded by Foveros would allow companies to use the best possible process for each component.
In addition, Intel says it invented a brand new insulation material to help dissipate heat more effectively.
A NEW WAY OF CONNECTING PARTS
Current package-on-package stacked designs take advantage of just a few hundred connections to connect things like the memory and processor in a system-on-chip, but the size and performance of the connections are quite limiting. Foveros gets around that by using etched silicon, just like EMIB, to facilitate a greater number of interconnections running at higher speeds.
However, instead of EMIB’s silicon bridges, Foveros puts thousands of microbumps on the surface of chips. The underlying package also has larger solder bumps, and these have direct faceto-face connections with the stacked chips by way of Through Silicon Via (TSVs) in the silicon interposer.
IT’S SUPER FLEXIBLE
Starting with Lakefleld, Foveros could enable a new breed of devices and systems. This includes more than just new portable PCs or convertibles and could encompass even foldable smartphones or dualscreen devices. Intel has already installed Lakefleld in two reference systems – a single-screen device and dual-screen clamshell – but the possibilities are endless.
With a flexible board like Lakefleld, Intel could scale from a low-power experience to a more powerful package for desktop PCs, which opens up plenty of new options.
