But the CeRAM could also go to multi-layer stacking, Yeric indicated.
"Regarding stacked arrays, we think it looks attractive compared to existing stacked embodiments (PCM, possibly ReRAM), but we think a non-hafnium based FeFET would ultimately be the best solution for cost, as 3D NAND has demonstrated." This point of view gives a reason why Cerfe Labs has also been given a license to develop ferroelectric FET devices by research partner Symetric Corp. (Colorado Springs, Colo.).
"Our focus is on CeRAM for the combination of scalability, speed, and power, especially in the embedded memory space. It is showing the potential to be 'more universal' than other options, which is why we are excited about it." But Yeric added that a third terminal would be needed for vertical stacking. Yeric said that while CeRAM could potentially be made into a FET it may be more straightforward for FeFET. "FeFET may not be quite as fast as CeRAM or scale to the same densities, but there is a lot of space for it to contribute to edge AI," Yeric said.
But in one important aspect of this potentially important memory element we have less information than we did five years ago and earlier. And that is of what it is likely to be made.
Going back to 2011 the early research was on carbonyl-doped nickel oxide as a potential bulk-switching RRAM non-volatile memory. Now Cerfe is saying it does not use nickel-carbonyl as a pre-cursor material and it has more than four CeRAM materials of proven capability and – for now – Cerfe isn't revealing those materials and their respective dopants and electrode materials.
Others have speculated that they may include hafnium-oxide, titanium-oxide and yttrium-titanium oxide besides nickel-oxide.
Yeric was prepared to talk about the high degree of controllability and flexibility Cerfe thas in the making of such memories.
Devices are now manufacturable using spin-on slurries, plasma vapor deposition (PVD) or high-precision atomic layer deposition (ALD), he said. "You can go after ultralow-cost IoT with the slurries, and you can go after high density memories with MLC [multi-level cell] using ALD. A sweet spot for most embedded applications may be the in-between, PVD."
A manufacturer could also vary the film thickness to tune the current and vary the doping chemistry and doping concentration. This could also be used to manage other trade-offs such as the switching voltage and voltage margins.
The technology also shows remarkably low temperature variability. This means that devices can work at close to absolute zero and at high temperatures. Testing to date has demonstrated performance from 1.5K to 115 degrees C, Yeric said. There is an expectation that the CeRAM switch will operate at up 400 degrees C.
This allows CeRAM to be a contributor to some cryogenic quantum computing control systems. "There is about a 50 percent fall off of current from 100K toward 1.5K but even at 1.5K it is a very good memory device and we expect to show millikelvin capability. This stability appears to apply to both voltage and current," Yeric said.
It may therefore be that CeRAM memories tuned for either extremely low temperature or extremely high temperature could be some of the first to appear on the market.
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