Macronix intros 2-bit per cell NOR Flash tech

Chicago (IL) - Macronix announced a new technology that could allow NOR Flash memory device to store twice the amount of data and keep the die within the dimensions of today's products.

The announcement is based on a 2-bit per cell approach that is not necessarily new, but uses a new nitride-based multiple bits per cell technology that is cheaper to manufacture than previous solutions and offers scaling potential for the future, Macronix said.

Typically, silicon-based floating gate NOR Flash memory products can physically store only one bit of information in each cell. The firm's "NBit" technology, however, physically stores two bits of information in each cell: The nitride-based cell "traps" the charge on one side of the cell and the charge does not flow to the other side of the cell unlike floating gate cells. As a result, another charge can be stored physically on the other side of the cell providing two bits per cell. Programming of each bit is performed by hot electron injection, erase is performed by band to band tunneling, and read by the reverse read mechanism.

According to Macronix, the process is simpler and easier to scale down to smaller geometries, since there is no floating gate in NBit. Initially, NBit is available in 32 MByte products. Down the road, the technology will scale beyond 1 GByte, Macronix said.

NOR was the first type of Flash and was developed from EPROM and EEPROM chip technologies. Equipped with an SRAM interface, NOR Flash has write and delete speeds that would be considered slow by today's standards, and can handle only a small number of write cycles (about 100,000). It is found in areas where permanently stored data needs to be only infrequently changed. For example, operating systems of digital cameras or mobile phones are stored on NOR Flash units. In contrast, storage cards typically use "NAND" Flash - which offers more than a million write cycles and higher write speeds.