Toshiba Memory Corp. has developed a prototype of a BiCS FLASH device that delivers 4-bit-per-cell (quadruple-level cell, QLC) technology. Toshiba claims that this is the world's first BiCS FLASH three-dimensional (3D) flash memory with a stacked cell structure.

Multi-bit cell flash memories store data by managing the number of electrons in each individual memory cell. Achieving QLC technology posed a series of technical challenges, as increasing the number of bit-per-cell by one within same electron count requires twice the accuracy of triple-level cell (TLC) technology.

Toshiba's prototype features a die capacity of 768Gb (96GB) with 64-layer 3D flash memory process. The QLC 3D flash memory also enables a 1.5TB device with a 16-die stacked architecture in a single package.

Shipment of the prototypes to SSD and SSD controller vendors for evaluation and development purposes started early June.