Crossbar plans to come to market in two phases, Minassian said. Initially, the company wants to license single-layer memory blocks as IP cores through foundries for use as embedded memory. After that, the company will develop stand-alone memories under its own brand, replacing NOR flash in code storage and NAND flash in data storage.
"We are in discussions with foundries. It will take a couple more quarters to get the technology into wafer fabs but I see embedded [memory] in the market in 2015. Meanwhile, it will take two to three years [from mid-2013] to get to stand-alone memories," he said
But the path for the introduction of innovative non-volatile memory is notoriously difficult. There are many similar ReRAM, conductive bridging and other technologies that are being researched but struggling to compete with the incumbent flash memory technology. Phase-change memory was thought to offer similar scaling benefits beyond NAND flash but the R&D phase took more than 40 years, and although it is now in the commercial marketplace and has some reported deployments, it is only made at feature sizes that are larger than mainstream flash memory.
Comparisons for Crossbar memory against contemporary flash memory. Source: Crossbar Inc.
Ron Neale, a memory device expert who has contributed review articles on non-volatile memory to EE Times, raised some areas of concern about the technology. One is the use of silver as an electrode material in the fab. Like copper, unless carefully controlled, silver can have a contaminating effect in a wafer fab. This might inhibit foundries from adopting the technology.
In email correspondence with EE Times, Neale said:
Silver is a fast diffuser and in the past it has been shown to have had a detrimental effect on MOS gate oxides. However -- although mostly as a BEOL process -- a good experience base of the use of silver pastes as conductors in direct contact with silicon is building from the photovoltaic industry.
A second area Neale raised is the blocking diode effect used for matrix isolation which, according to a 2011 PhD thesis out of University of Michigan, while apparently robust was not at that time fully understood. "There are at least a couple of candidate locations in the memory cell for the site of the non-linear matrix-isolating element," Neale said in email. A third area is the thermal-dependence of the filament creation and maintenance, which Crossbar describes as being "minimal."
"So far Crossbar appears to have done most things in the right way and this could be the flash-replacement non-volatile memory that finally takes off," Neale said. "All aspects of the claimed performance of their ReRAMs can be verified in large arrays -- but that should also mean the publication of the full details of reliability testing." he added.
Since its founding in 2010, Crossbar has filed more than 100 patents related to the development and manufacturing of ReRAM with 30 already issued. One of the biggest claims that may yet aid adoption is that the technology is completely CMOS compatible and can be integrated into the back-end-of-line of any standard CMOS wafer fab.