Crossbar announces RAM technology almost ready for launch
The RRAM manufacturer Crossbar unveils new aNAND flash replacement. RAM (RAM or ReRAM) is designed to store data by creating resistance in a circuit rather than trapping electrons within a cell. The company is currently working to deliver their designs to commercial use.
NAND is falling behind its rival ReRAM on many aspects. NAND has a limited program cycle, its lifespan wears out as cells become smaller, resulting in a corresponding increase of error correction. There are few performances NAND flash devices can achieve and they have no other option but to improve the NAND controller or the system interface rather than the unsatisfactory performance of the NAND itself.
The operating and performance characteristics of ReRAM are higher. For instance, it doesn’t require formatting before it’s programmed and it has higher speed than NAND flash, plus it doesn’t draw as much power. According to Crossbar, NAND requires 1360 picojoules per cell to program whereas RRAM does its job with only 64 picojoules per cell. In addition to low power consumption, the new discovered technology should support storing two bits of data per cell (analogous to MLC NAND) and being stacked into 3D layers.
It’s also possible that this new technology could be used to reduce the complexity of the microcontroller itself, a noticeable improvement considering how complexity and cost have been increasing as the task of flash management becomes more complicated.
Even though Crossbar showed that its designs can scale up into the terascale, it remains to be seen when it’ll be able to deliver products at that density to market. The company is now licensing to ASIC, FPGA, and SoC developers, with samples arriving in 2015.
NAND flash will dominate the memory market for many years to come. There are economic reasons for that. Samsung, Intel, Micron paid billions of dollars for NAND production and it isn’t likely they’ll suddenly switch suppliers. The strategy to survive in tech industry isn’t always to adopt the latest technology but to continue extending the same product at lower costs. Storage manufacturers tend to use the cheapest technology for decades even though other technologies offer better performance.
3D NAND flash (or V-NAND) will maintain its top spot in non-volatile memory market for at least three more years. That doesn’t mean RRAM won’t make a presence among consumers or other businesses. There are some companies that have already turned to higher performance designs like PCI Express or the upcoming NVMe which enables faster response times for high-frequency stock trading or other latency-critical applications. RRAM’s running speed may not seem higher than NAND’s but it's capable of better response times at latencies that matter to computers, thus determining some segments to adopt the equipment.
There are other versions of resistive memory, such as phase change memory (PCM) that can indeed offer better performance than NAND flash but also at a higher price. RRAM uses conventional CMOS hardware and can operate at scales down to 5nm. NAND flash, in contrast, isn’t expected to scale below 10nm.
3D NAND will allow companies to introduce higher nodes. For instance, Samsung’s current V-NAND is built on 40nm process technology. It’s a good approach that could work for the next five to ten years but in order to improve power consumption and take computing to the next level we should move to a new form of memory, and right now RRAM seems the most capable to meet these challenges.