SEOUL -- Samsung Electronics has developed technology that could increase the data capacity of NAND flash memory chips by as much as 50%.
The technology, called 3-bit/cell multilayer cell NAND, works in two ways to raise memory capacity. First, 3-bit memory chips can hold 50% more data than their conventional counterparts. Each memory cell can handle 3 bits of data, instead of the conventional 2 bits. Second, layering multiple memory cells makes it possible to bolster memory capacity without increasing the chip's footprint.
Samsung and other manufacturers have been selling single-level 3-bit NAND chips. But the South Korean firm recently began mass producing the multi-level type, a world's first. Multi-level NAND chips are made by vertically stacking memory cells and connecting them by numerous electrodes.
Conventional single-layer chips have improved memory capacity and lowered costs by narrowing circuit width. But many believe this method will soon hit the wall because there is a physical limit to how narrow a circuit can be made. Multi-level chips can raise memory capacity without narrowing circuit width, through layering. This makes it possible to produce higher-capacity chips without increasing the footprint.
Bargains
Samsung started mass production of 24-level NAND chips last year, then increased the number of layers to 32 in May. But these are all 2-bit cells. The new technology has made it possible for the company to use some of 3-bit cells in 32 layers,not 2-bit.
Using 3-bit cells also enables Samsung to address the major issue with multilevel chips -- high costs due to the complex production process. This is achieved by reducing the number of layers that are necessary to offer the same amount of memory capacity.
Samsung plans to capitalize on the lower production costs by using 3-bit multilevel NAND chips in its solid-state drives for personal computers. "We want to accelerate the shift from hard drives to NAND-chip-based solid state drives," a Samsung official said.
The company has been selling 2-bit multilevel NAND-chips mainly for use in data center servers. Multilevel chips are less prone to data-write errors and other malfunctions. Because high reliability is crucial for servers, multilevel chips have strong appeal for data centers even if they cost more.
For now, multi-level NAND chips are more costly to produce than single-level chips. Samsung believes it can change this.
"We will be able to beat single-level NAND cell production costs by increasing the number of layers further in the future," a company official said.
Related stories
