Crossbar recently chalked up another milestone in its quest to get on-chip non-volatile resistive RAM (ReRAM) technology to market.
The Santa Clara, California-based startup licensed its core ReRAM intellectual property to Microsemi, a semiconductor supplier to the military and aerospace industry. The companies plan to collaborate on the research, development and application of the Crossbar ReRAM into Microsemi products designed for 16, 14, and 12 nanometer (nm) process nodes.
ReRAM is a type of non-volatile memory that consumes less power and offers faster reads and writes, higher endurance and greater storage density than NAND flash. But Crossbar does not position its ReRAM as an alternative to technologies such as flash-based solid-state drives (SSDs). The initial use cases for ReRAM will more likely be under the covers in CPUs, field programmable gate arrays (FPGAs), and system-on-a-chip (SoC) architectures, possibly as an alternative to slower static RAM (SRAM) or less energy-efficient dynamic RAM (DRAM), according to Sylvain Dubois, vice president of business development and marketing at Crossbar.
Dubois expects the embedded Crossbar ReRAM technology to reach products that businesses or consumers might use in 2019.
ReRAM use case example
In the meantime, Crossbar demonstrated potential use cases in “artificial intelligence applications at the edge” – designed for devices such as surveillance cameras and mobile phones – at the recent Embedded Vision Summit in San Jose, California. The startup showed off ReRAM test chips with applications designed to recognize faces and license plates. Dubois said the test chips integrate the algorithms and the database, enabling classifications to be done efficiently at low latency and low power, with no need to communicate with a distant cloud-based database.
Alternative technologies that a designer might have chosen for such applications include static RAM (SRAM) and dynamic RAM (DRAM), according to Dubois. But he claimed SRAM would have been slower and DRAM would have consumed more energy than the Crossbar ReRAM.
Microsemi did not disclose the types of products that might incorporate the Crossbar ReRAM technology nor the foundry with which it is working. The company’s product line includes PGAs, controllers, communications chips and artificial intelligence computing chips.
“What is unique is that this Microsemi deal is targeted at 1x nanometer,” Dubois said. “Getting to the point where you can prove the scalability is a major milestone. Now we have not only a customer but we also have a foundry that is getting access to embedded ReRAM at 1x nanometer.”
Dubois said Crossbar started its non-volatile ReRAM commercialization phase on 40 nm process nodes with Semiconductor Manufacturing Corp. (SMIC). He said Crossbar also works with two other foundries and licenses its ReRAM to about a dozen chip designers.
Crossbar ReRAM nanofilament technology is built on standard complementary metal oxide semiconductor (CMOS) processes, and the company claims it will scale to below 10 nm without impact to performance.
“The big trick is to get into high volume production because the most important thing in semiconductors is to get the volume high enough so you can drive the costs out,” said Jim Handy, general director and semiconductor analyst at Objective Analysis.
Handy said the Microsemi agreement with Crossbar shows the semiconductor supplier took a hard look at the ReRAM, decided it’s a good technology, and expects other companies to sign on. He said the 1x nanometer process achievement indicates Crossbar could be looking at use cases where NOR flash won’t work any longer due to scaling issues.
“Microsemi supplies stuff for aerospace, and in space, there’s a lot of radiation. Radiation tends to cause NOR flash, or any flash, to lose its content. The radioactive particles go through the chip and drag the electrons out of the floating gate,” Handy said. “The Crossbar metal filament technology doesn’t use electrons. And nuclear particles can go zipping through the chip and not destroy bits.”
Handy said enterprise users aren’t likely to notice ReRAM in their servers or storage systems because it would be buried in places they won’t see. But he said Crossbar ReRAM could lower the cost of SSD controllers marginally by allowing them to scale better.
“Now 80% or more of the cost of the drive is the NAND flash. So this is going to make a small difference, but it will make a difference,” Handy said.