Can ReRAM replace flash?

Can ReRAM replace flash?

Summary: Panasonic's plans to commercialize ReRAM starting this year puts this NVRAM technology in front of the race to replace NAND flash. What is ReRAM and why is it better than flash?

TOPICS: Hardware, Processors

Flash may not scale below 10nm - even 19nm is a bit of a stretch - but what can replace it? ReRAM (or RRAM: resistance RAM) now moving into commercial production has several advantages over flash. It is now the leading candidate for global NVRAM domination.

The trouble with flash Flash, like DRAM, stores a bit as an electrical charge. As flash feature sizes shrink - or the number of bits per cell increases - so does the number of electrons storing the bit.

At some point the number of electrons will get too small to be reliably read or stored. Improved signal processing and ECC can help, but these carry their own overhead.

What is ReRAM? ReRAM uses electrically-altered resistance, not charge, to store a bit: high resistance is a 1; low resistance is a 0. Resistance is easier to measure than a cloud of a few hundred electrons.

The resistance is changed by applying voltage, like flipping a switch. One advantage: the required voltage is a fraction of that needed for flash writes, handy for low-power devices.

Several materials can be used for ReRAM. Some offer the endurance - millions of writes - and retention that beat flash, while others offer the speed of DRAM.

Other advantages include:

  • Density. Researchers in Taiwan have have shown that standard processes can build tiny ReRAM cells.
  • Cost. Manufacturing with fewer and simpler steps than flash requires has been demonstrated.
  • Write-life. Some ReRAM can be written millions of times vs. the 10,000 writes of MLC flash.
  • Flexibility. Depending on how it is architected, ReRAM can be optimized for density - mass storage - or speed.
  • Materials. A variety of materials can be used to create ReRAM. As research continues it is likely we'll see more interesting possibilities emerge.

The ultimate - and perhaps impossible - goal is a device that is as fast as DRAM with the retention of flash.

What about phase-change? ReRAM's biggest competitor is phase-change memory, which uses heat to change resistance. But it appears that the power required to switch states is making PC-RAM uncompetitive with ReRAM.

The Storage Bits take With Panasonic, 4DS, Sematech and others working on it, ReRAM appears to be the consensus favorite for the Next Big Thing in NVRAM.

ReRAM's path is not entirely smooth: flash has huge momentum and many researchers working to extend its life; and the basic physics behind ReRAM are still not well understood. But it looks like ReRAM has all the pieces needed to move ahead in the next 5 years.

Perhaps we'll get that ultimate memory device - fast as DRAM, non-volatile and cheaper than either - this decade.

Comments welcome, of course.

Topics: Hardware, Processors

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  • RE: Can ReRAM replace flash?

    Lower latency than flash, simpler production and more write cycles. If ReRAM delivers on just two of those three it will revolutionize storage yet again.

    Regardless, one thing is crystal clear: Storage is moving inexorably to solid state. Mechanical disks will be relegated to the role of tape.
    • RE: Can ReRAM replace flash?

      When? Before or after we reach Singularity?
      I've heard people wishing for solid state to replace hard drives for the last 4 years. Seagate's 3 TB drive is now $230 on Newegg.
      • RE: Can ReRAM replace flash?


        Well, if you watched Transcendent man, then you know that the rate at which we reach new technologies is accelerating. We're discovering new tech. quicker and quicker. So it could be within the next couple of years.
      • RE: Can ReRAM replace flash?


        Well put. But progress is inexorable.
      • RE: Can ReRAM replace flash?


        4 years? Try 25. Remember bubble memory? Hard drives were doomed back then, except that they, er, weren't
    • RE: Can ReRAM replace flash?

      @ChristophWeber <br><br>You act as if tape is dead . . . . <br>Perhaps if you understood that tape is for, and has been for the last few decades, primary backup and archive media.
      • RE: Can ReRAM replace flash?

        @mgaul Why do you have to understand, you even know or you don't. <a href=""><font color="#000000">uk seo company</font></a>.
  • Robin... please specify that your talking about memories...

    Some might confuse your title and think that something called "ReRAM" will replace "Adobe Flash".

    As for the technology, as always, if the manufacturers can deliver, the market will follow. Else it's bubble memory part deux.
    • RE: Can ReRAM replace flash?

      Replace Adobe? I can always hope.

      But I'd hope the 1st sentence would give most folks a clue.

      Robin Harris
  • RE: Can ReRAM replace flash?

    Nothing is real until the product is manufactured in a desirable, usable form at a reasonable price and the stores and assemblers of products offer it to us.
    Hope I live long enough to see it and some of the other wonderful ideas make it to market at a reasonable price.
    • RE: Can ReRAM replace flash?

      wow what on earth is that? i can 't believe that how you see it. <a href="">empires and allies hack</a>
  • RE: Can ReRAM replace flash?

    Not gonna happen.
  • RE: Can ReRAM replace flash?

    I imagine that ReRAM, using resistance instead of bits as a medium, would be extremely dependant on a constant and precice level of power. Even within a PC, voltage levels fluctuate within a fraction of a percent.

    An analytical example: When applied to ones and zeroes. Your base value is 1. If your voltage drops by 0.2 volts, a value of 0.8 would be rounded to a 1, and no harm is done. Or if your base is 0, a .25 overvoltage is still registered as zero.

    As a proof of concept example. I have an old Palm Tungsten E2 which has a weak battery. The touchscreen utilizes resistance based on x and y (horizontal and vertical based on where you touch) values. When the battery is weak and delivers less than optimal current, the CPU, which uses ones and zeros still works fine for as long as I can get the battery to last, but the touchscreen which relies on resistance values will return bad values and will never stay callibrated.

    With resistance, and change in value difference changes the value entirely. I'm no expert on ReRAM, but it seems to me that any memory controller utilizing ReRAM would have to bias it's output values by it's line voltage or find a way of producing an extremely level input line.