Integrated device manufacturer, Macronix, has produced a new type of self-repairing flash memory. The new NAND memory cell with built-in heat plates applies high temperatures across its architecture which repairs decayed memory fragments.
The heated memory cell's design is outlined in a paper that will be presented at the International Electron Devices Meeting 2012. It describes the process by which 800 degrees Centigrade of heat is applied to small groups of memory cells for milliseconds at a time, restoring damaged locations to working order.
The process is power-intensive but the heating is conducted infrequently, while the device is inactive and connected to a power source. The memory cell also boasts the unforeseen benefit of faster erasing.
“Further down, this may evolve into a ‘thermally assisted’ mode of operation that gives both better performance, such as the faster erasing and better endurance flash memory,” Hang-Ting Lue, project director of Macronix, told IEEE Spectrum.
This system of self-repair builds on past research which found that degraded materials in old flash memory can be repaired through the use of heat. Early applications of this theory proved impractical as memory chips would be left to bake in a 250 degrees Centigrade oven for hours.
Tests conducted by Macronix have found that its custom flash chip can withstand 100 million program/erase (PE) cycles, however, that is just a general estimation as it would take months to ascertain the devices true upper limit of reliability. Comparatively today’s flash memory solutions a can only achieve 10,000 PE before reliability begins to suffer.
“We do not know what would eventually cause the device to fail, since we have not seen the end-of-life signals yet,” said Lue.
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