6-bit flash memory tested in Japan: while it operates at –200 ° C

Two years ago, the Japanese company Kioxia (formerly Toshiba Memory) announced the successful development of NAND PLC flash memory with

This promised a 25% increase in areal density compared to QLC NAND (4-bit) memory, but halved the wear tolerance for the 10nm class process to 35 rewrite cycles.However, engineers have not stopped there and have recently tested 6-bit HLC 3D NAND memory and plan tocreate an 8-bit OLC NAND.

The information in the NAND cell is encoded with a numberstates of charge (voltage) and is determined by the value 2 to the power, where the degree is the capacity of the cell. For example, for MLC memory, these are four gradations of voltage levels (22), and for the popular 4-bit QLC today, there are already 16 values ​​(24). For a memory with six bits in each cell, it is necessary to hold already 64 levels, and for an 8-bit memory - 256 values. This will incredibly load the memory controller, which will have to restore and correct all this at each operation, but physics and chemistry of materials also stand against this.

To test the operation of a 6-bit NAND cell,Kioxia engineers cooled the memory sample to a temperature of –200 °C. This stabilized the characteristics of the material and simplified the cell design. The experiment showed that in this state, a 6-bit cell can write and store data for up to 100 minutes without destruction, and can also withstand up to 1,000 rewrite cycles. The developers hope that at room temperature such memory will withstand up to 100 rewrite cycles. The achieved result allows us to hope that over time HLC and even OLC memory will appear.

However, even if scientists at KioxiaIf they can make HLC and OLC NAND work at room temperature, they will need to develop corresponding controllers. Their task is to reliably read and write data from such flash memory. Such controllers will need to support extremely complex ECC algorithms, which will require significant computing power. Will such controllers be too expensive to offset the capacity benefits of 3D HLC and 3D OLC NAND? And what performance can future HLC drives offer? As Tom's Hardware notes, "only time will tell," but experts don't expect TLC to disappear from the market anytime soon.

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