IBM scientists have reported success in the discovery of new memory that is 50x faster and cheaper than Flash memory. Their discovery appears to be a breakthrough in the development of phase change memory (PCM). For the first time IBM researchers have demonstrated they are able to store 3 bits of data per cell reliably.
At the IEEE International Memory Workshop, they presented the prototype of the memory which performed an endurance exercise of one million write cycles. PCM should be able to last for 10,000,000 write cycles which is far more than the 3,000 write cycles normal USB sticks are specified at. PCM combines the speed of DRAM with the non-volatility of NAND while its price will likely be slightly more than NAND and less than RAM memory.
PCM works because its materials exhibit two stable states, the amorphous (without a clearly defined structure) and crystalline (with structure) phases, of low and high electrical conductivity, respectively.
To store a '0' or a '1', known as bits, on a PCM cell, a high or medium electrical current is applied to the material. A '0' can be programmed to be written in the amorphous phase or a '1' in the crystalline phase, or vice versa. Then to read the bit back, a low voltage is applied.
Previously scientists already successfully demonstrated the ability to store 1 bit per cell in PCM, but at the IEEE International Memory Workshop in Paris, IBM scientists are presenting, for the first time, successfully storing 3 bits per cell in a 64k-cell array at elevated temperatures and after 1 million endurance cycles.
According to the researchers, the 3 bits per cell is important because at that density the cost of PCM will be significantly less than DRAM and closer to Flash memory.
