A new high-speed memory technology from stealthy startup Nantero is one step closer to reshaping data center storage. Nantero announced on Tuesday, June 2, that it had closed a $31.5 million series E financing round, bringing funding up to a total of $78 million and opening the door to further development and future volume production of its carbon nanotube storage technology. Nantero, which has been quietly working on its carbon nanotube storage since 2001 and has been in low-volume production since 2004, is making big claims for its technology.
The new memory, called NRAM (non-volatile RAM), uses carbon nanotubes as nano-scale physical switches. Nantero NRAM uses a thin film of carbon nanotubes deposited on a standard silicon substrate situated between two electrodes. Applying a small voltage across the electrodes causes the carbon nanotubes to change their alignment, effectively opening or closing a physical circuit between the two electrodes. Once switched, the carbon nanotubes retain their alignment indefinitely. Nantero claims that NRAM will store data for over 1,000 years when operating at 85°C, or for up to ten years at temperatures as high as 300°C. The carbon nanotube memory is also proof against cold, magnetism, radiation, and vibration, enabling it to be used in hostile environments. Switching times are said to be as fast as DRAM, but without the need for continual memory refresh, the power requirement is substantially lower. Endurance also looks to be good, with write cycles of up to 10E11, far surpassing the 100,000–1,000,000 erasures per block that the best SLC NAND flash can achieve.
Early NRAM devices have a relatively large cell size (140nm) with single bit memory storage. However, Nantero claims the technology can scale down to cell sizes of 5nm and can also support multilevel cell operation, which will enable storage densities up to 128 GB. Crucially, it will be possible to volume manufacture NRAM in standard CMOS fabs without having to invest in new equipment. Amid concerns that the performance and scalability limits of flash memory storage will be reached by 2022, NRAM should be ready for large-scale adoption soon enough to address long-term storage challenges.
NRAM is not the only new storage technology in play. RRAM (resistive RAM) and MRAM (magnetoresistive RAM) are already being used on a limited basis, and phase-change memory (PCM), which is being developed jointly by IBM and Samsung, has yet to reach production.