Flash memory seeks to expand the physical limit

Flash technology will replace DRAM world domination in about 5-7 years if it does not encounter physical limitations too quickly.

NAND flash memory, currently used in digital cameras and MP3 players, is under intense competition among manufacturers. " The potential market for flash next year will be cameras and camera phones ," said Eli Harari, CEO of SanDisk, a storage device company.

NAND will take over DRAM, the main memory in computers, because production costs are no longer as expensive as a few years ago. IBM and many other companies are also building NAND-based semiconductor servers.

However, Harari said that the current flash technology could only last for 4 to 5 generations before a new solution needed to survive.

But improving NAND chips is becoming more complicated because the components that make up the chip can hardly "shrink" any more. The tunnel oxide layer is only capable of shrinking to 80 angstroms (units of light wavelength) while in other chips, this layer can be reduced to 12 angstroms.

The 32-nanometer NAND chip will appear later this decade and the 20 nm generation will be available a few years later. Then, NAND memory will have 256 Gb capacity and the price per bit is only 1/10 compared to the current. However, since then, flash production materials and technology are difficult to go further.

SanDisk sought a 3D memory chip solution (the technology of Matrix Semiconductor they bought a few years ago). However, Matrix chips only support write once, ie users cannot delete old data and write new data. SanDisk is continuing to fix this problem.

Many manufacturers consider adding bits to each memory cell. Currently, the highest chip density is 2 bits / cell. The chip with 3 bits / box is expected to appear in the next 2-3 years.

Meanwhile, a number of other companies focused on understanding phase transformation or actuator.