Is your gadget using secondhand memory? Predictable senility allows boffins to spot recycled NAND chips
Not what you'd expect in industrial kit
University researchers have developed a new method for rooting out recycled memory chips in industrial control devices.
The group from the University of Alabama, Huntsville say their technique could help vendors spot and remove older flash memory chips that would otherwise jeopardize the stability of embedded devices in the medical, aerospace, and military fields.
They are presenting the research as part of the 2018 HOST Symposium on Tuesday.
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With the embedded device market booming and semiconductor companies hard-pressed to keep up with demand, the re-circulation of older memory chips has grown in recent years. Because chips become more apt to fail as they get older, newer devices that are outfitted with recycled chips will be more likely to experience problems.
"Detection of recycled Flash with high confidence is challenging due to the variability among the different Flash chips caused by process variations," explain suthors Preeti Kumari, Bahar Talukder, Sadman Sakib, Biswajit Ray, and Tauhidur Rahman of the University's electrical and computer engineering school.
"There is very few works on detecting recycled memory chips, and unfortunately, all of them require an extensive database to maintain which is impossible for several electronic systems."
Rather than try to maintain those databases, the researchers instead chose to study the way NAND memory chips age. They found that, as a chip undergoes multiple program erase (PE) cycles (with information being written and then overwritten), small imperfections will be created in the transistors that will very slightly increase the time it takes a chip to perform erase operations.
This timing change, the researchers say, occurs in such a reliable and uniform way that it can be measured across memory chips from different manufacturers.
The study found that, at about 150 PE cycles, memory chips show enough of a reduction in timing cycles to be reliably distinguished from new chips (that's about 3 per cent of the expected 5,000 cycle lifespan).
The group hopes that the techniques could be used by manufacturers to test and weed out the older chips that, in an industrial control device, would cause the entire unit to go down should they fail. In the process, they hope to make embedded and industrial devices more reliable over the long-term. ®