Heated flash memory up to 800 ° C

    Macronix, a major Taiwanese flash memory manufacturer, has developed technology to extend the life of flash memory chips from the current 10,000 write cycles to at least 100,000,000 write cycles . Macronix engineers say the life span may be longer, in the region of 1 billion cycles. It takes several months to verify this.

    The way to extend the life of flash memory is rather trivial, it was discussed earlier, but so far no one could normally implement it. We are talking about heating the microcircuit for a few milliseconds to a temperature of 800 ° C.

    Degradation of flash memory is associated with the accumulation of residual charge each time the cell is overwritten. After several thousand rewriting cycles, this residual charge increases to such an extent that further use of the cell as a storage medium becomes impossible.

    Specialists have long said that heating to a sufficiently high temperature allows you to get rid of the residual charge. After eliminating the residual charge, the microcircuit began to work “like new”. It was assumed that for this it was necessary to heat the chip to 250 ° C for several hours. Naturally, in real conditions this cannot be done.

    Macronix engineers found a solution using phase-change memory (PRAM) methods, a non-volatile memory in which the carrier of information is chalcogenide. This substance, when heated, switches between two states: crystalline and amorphous. The substance in the PRAM microcircuit changes its state when heated to 600 ° C for several nanoseconds. Macronix specialists decided to test how flash memory cells react to short-term heating to high temperatures. As a result of the experiments, they discovered a “healing effect” in the region of 800 ° C.

    It turns out that it is enough to periodically heat the memory to 800 ° C. Macronix has designed a special memory chip with miniature heaters. For the new design, we had to modify the traditional scheme of the flash memory cell (in the illustration).

    Cell heating is rarely required, and you can “fry” one cell at a time, so this procedure will not be too burdensome for the battery of a mobile device, said Hang-Ting Lue, Macronix Deputy Director and one of the authors of the scientific work .

    Macronix will present the research results at the IEEE International Electron Devices Meeting 2012 , which will be held December 10-12 in San Francisco.

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