Intellectual property licensor Rambus Inc. has been working quietly for three years on metal-oxide based resistive RAM technology and has signed up "a lot of customers" for technology, according to CEO Ron Black. It is now looking likely that a number of players could come to contest the NAND flash replacement with various ReRAM approaches in 2016.
In the case of Rambus (Sunnyvale, Calif.), it is working with customers on ReRAM development and Black does not see it being a significant revenue generator in the short-term, he told analysts on a conference call to discuss Rambus' 4Q14 financial results.
But Black said that Rambus has made "significant progress" with the memory over last two years. The company announced it had signed an architectural license with Tezzaron Semiconductor Corp. (Napeville, Illinois), a supplier of 3D and 2.5D memory, memory subsystems, and memory-intensive SOCs immediately prior to announcing its financial results (see Tezzaron Agrees to License Rambus’ ReRAM IP). Tezzaron is expected to build storage-class 3D non-volatile memory systems for military, aerospace and commercial applications. Tezzaron's first ReRAM devices are scheduled for production in 2016.
"While we've not discussed it much in the past, we have been quietly working on our Resistive RAM technology or RRAM, which is a higher speed, next generation technology to replace or complement conventional flash memory," Black said on the conference call. "The performance of resistance RRAM has been very good. We have a lot of customers that we are working with. We just haven’t announced anything. I don’t expect that this is going to be a significant revenue generator in the short term but the performance of it especially as you tune it, could be very interesting."
Black told the analysts that the technology still has some issues with regard to temperature stability. "Probably the biggest hurdle in terms of opening it up is getting the high temperature stability. So in consumer applications, I think the existing temperature ranges that we have are fine but to really hit industrial and automotive grade we are going to have to continue to tweak or with our customers, going to have to continue to tweak the bit cells to really ensure that they are stable. So if we can get pass that, I can see it becoming mainstream rather quickly."
Rambus acquired its ReRAM technology, originally called CMOx, when it acquired Unity Semiconductor Corp. for $35 million in cash in February 2012. Unity has been working on the technology without for a decade without being able to come to market prior to being acquired. At the point of acquisition the company had developed an extensive patent portfolio on ReRAM and the deal allowed the Unity team to continue with R&D with a view to eventually licensing the technology out.
Many companies in the United States and Asia have been developing resistive RAMs based on multiple operating principles and many materials systems. The technology appears one of the favorites to replace NAND flash, which struggles to scale below 20nm.
Adesto Technologies Corp. (Sunnyvale, Calif.) is one company that has come to market with its conductive bridging RAM (CBRAM) non-volatile memory. CBRAM was originally developed at Arizona State University where it was also known as Programmable Metallization Cell technology. It involves the movement of metallic ions to form and break a conductive bridging filament. Although original research favored silver ionic transport Adesto has switched to copper, which is more readily available in wafer fabs.
A more recent ReRAM startup is fabless chip company Crossbar Inc. (Santa Clara Calif.), which says it is continuing to make progress with its silver-over-amorphous-silicon non-volatile memory technology. While the company expects to get silicon back from manufacturing partners in 2015 it is now saying 2016 is when its stand-alone ReRAM could be available.
Meanwhile researchers from Micron Technology Inc. and Sony Corp. have presented details of non-volatile 16-Gbit ReRAM based on a copper ionic transport memory.
If and when ReRAM market develops there promises to be considerable legal action as companies cross-license or contest each others patent portfolios. Rambus has some of the longest-established patents in the field and a chance to establish prior art.
Rambus announced a net income of $7.8 million on revenues of $72.0 million for the fourth quarter of 2014. The revenue was flat with the same quarter a year before and the profit compared with a net loss. For the full 2014 year Rambus made a net income of $26.2 million on revenues of $271.5 million, up 2.8 percent compared with 2013.
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