Invensas, a subsidiary of chip microelectronics company Tessera, has discovered a way of stacking multiple DRAM chips on top of each other. This process, called multi-die face-down packaging, or xFD for short, massively increases memory density, reduces power consumption, and should pave the way for faster and more efficient memory chips.

Multi-die face-down packaging is exactly what it sounds like, and the Invensas press release actually describes it a “shingle-like configuration” — i.e. each of the individual dies is staggered slightly, like roofing tiles. Much like a normal desktop DIMMs and laptop SO-DIMMs, each of the stacked dies is wired to each other in series — but in this case, the connections are much shorter, as they only have to run a few micrometers to the chip below it. This is where all of the power and speed enhancements come from: shorter interconnects mean less power is needed (and thus less heat is dissipated) and signals propagate faster.

Multi-die memory chips aren’t exactly new, mind you; various fabs have tried to implement processes along similar lines, and there are a handful of CPUs and GPUs that feature stacked DRAM, but for the most part silicon chips have remained resolutely flat. With humanity’s newfound love for mobile computing, however, physical space is now at a huge premium, and 3D packaging techniques (as opposed to 3D transistors) are a very hot sector. Lower power consumption is obviously very important in the mobile space, too — but it’s even more important in data centers and high-performance computing sectors where memory and relevant interconnects can account for a large percentage of total power usage.

For now, Invensas has only managed to commercially produce a memory chip with two RAM dies stacked on top of each other, but four- and eight-stack chips are on the roadmap. The dual-stack chip will be showed off at the Intel Developer Forum (IDF) next week, and hopefully some actual hands-on benchmarks will appear soon after. It’s also safe to assume that these xFD chips will be very expensive to begin with — but having said that, Invensas assures us that conventional chip fabrication processes can produce xFD packages, so we’ll see!

Read more at BusinessWire (Invenas press release) or hit up Invensas’ antiquated website