Unity Semiconductor

TORONTO – Tezzaron Semiconductor will be the first customer to incorporate Rambus oxide-resistive memory (ReRAM) technology in forthcoming devices through an architecture license that provides Tezzaron access to system IP, specifications and validation suites to design differentiated chips using ReRAM.

ReRAM, sometimes known as RRAM, operates by changing the resistance of special dielectric material called a memresistor, whose resistance varies depending on the applied voltage. The main advantage of ReRAM over other non-volatile memories is its high switching speed. The thinness of the memresistors means it has potential for high storage density, greater read and write speeds, lower power usage, and cheaper cost than flash memory.

Bob Patti, Tezzaron’s CTO, said the company sees short-term potential for ReRAM in military, aerospace and HPC applications where it can meet the power and performance requirements, and long-term opportunity in more commercial memory applications. Tezzaron is always on the look-out for new memory technologies, he said, and ReRAM fits into the emerging market of storage-class memory.

Patti said ReRAM offers very high endurance for military and aerospace customers as well as radiation hardness. “It’s much more robust than standard flash.” He sees it having the potential to replace DRAM as it could scale better in the long term, perhaps as low as six nanometers.

ReRAM fills the gap between what DRAM and flash can provide while being highly reliable and high speed, said Gary Bronner, VP of Rambus Labs. In addition to the aerospace and military applications that Tezzaron is eyeing for ReRAM use, he said Rambus sees an opportunity for Internet of Things devices, in part because of its low power qualities.

Rambus has been working on ReRAM since acquiring the technology through its acquisition of Unity Semiconductor in early 2012. Unity was working on a metal oxide-based cross-point two-terminal non-volatile memory cell under the name CMOx, which Rambus renamed ReRAM.

CMOx was intended as a NAND flash replacement, said Bronner, but since acquiring Unity, Rambus has focused on pivoting the technology and sees the immediate interest in ReRAM for embedded applications that require ultra-low power non-volatile memory. While it could be a replacement for NAND flash and DRAM in the long term, 3D NAND is addressing the current scaling issues for that technology, although the future of DRAM is a little less clear.

The concept of ReRAM goes back further than the efforts of Rambus. Unity's work on the technology dates back to 2002. In 2011, researchers from the Samsung Advanced Institute of Technology and the department of physics at Sejong University in Seoul, Korea reported on a non-volatile resistive RAM with a read-write endurance of more than one trillion cycles. Elpida Memory announced the development of a ReRAM prototype in early 2013 with plans to commercialize towards volume production of a gigabit-scale ReRAM in 2013.

Jim Handy, principal analyst with Objective Analysis places ReRAM in category he calls “exotic memory, ” which has three key characteristics: it’s non-volatile, high speed, and low power. These memories aren’t often cheap and tend to be niche. ReRAM could become a cheaper alternative in some niche applications, including those that require SRAM with battery power, something MRAM is doing.

Ultimately, it’s cost that determines the uptake of these niche memories, and if ReRAM finds more opportunities to expand markets, its cost will come down, ” said Handy. “Alternative memories are getting into the market by replacing the most expensive existing option, then the second.”

Handy said Tezzaron is essentially a pioneer in a market that hasn’t developed yet, but that ReRAM is making rapid progress given that it has really hasn’t done beta sampling but has been licensed to go into production.

Patti couldn’t give specific details on future products using ReRAM, but Tezzaron plans to build ReRAM into storage-class 3D memory devices for military, aerospace and commercial applications, as well as implement ReRAM in an assortment of SoCs, FPGAs and processors to take advantage of the split-fab production experience of Tezzaron’s fabrication subsidiary, Novati Technologies, which add hundreds of megabytes of storage to a logic device manufactured in a standard commercial fab.

The first in Tezzaron’s family of Rambus ReRAM devices is currently in the design phase and is expected to go into production in 2016. More broadly, Patti said the company focuses on creating devices with self-repair features for devices that can’t be easily accessed for maintenance, such as satellites and other space-bound equipment, such as rovers on Mars that have had partial flash memory failures.