Science

Hot Flash The Secret To SSDs That Will Outlast The Universe

Heat is never a desired quality in consumer electronics. Running your chips at high temperatures reduces their life and when it gets to extremes, kills performance thanks to throttling. Not so when it comes to flash memory, where a lot of heat, applied for milliseconds at a time, can allow a NAND cell to survive 100 million write cycles without breaking a sweat.

For comparison purposes, multi-level cell (MLC) and triple-level cell (TLC) NAND used in most flash drives today last ~5000-10,000 and ~1000 cycles respectively, though different manufacturers, wear-levelling algorithms and usage scenarios make the precise lifespan of an SSD difficult to predict.

So, 100 million cycles is a big deal, if entirely overkill. A report on IEEE Spectrum details the discovery, made by Taiwanese memory manufacturer Macronix. It’s common knowledge that writing to NAND chip slowly erodes the insulation surrounding its transistors. Eventually, it gets to the stage where the chip is rendered incapable of further writes.

However, Macronix found that the chips could be “healed” by applying temperatures in the 800°C range for a few milliseconds via special pulses. These pulses can be delivered by hardware built into the flash drive, but the company had to hit the drawing board a number of times to get the design right.

Macronix’s researchers were inspired by phase-change RAM, an alternative to NAND. As the IEEE Spectrum article describes, PCRAM stores information by heating gates made of “chalcogenide” glass. The heat changes the physical state of the glass, allowing it be marked as written to or empty.

100 million cycles might enormously exceed the needs of nearly everyone, but it does bring SSDs a significant step closer to superseding venerable magnetic media.

[IEEE Spectrum, via Arstechnica]

Image: Alan / Flickr, licensed under Creative Commons 2.0

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