Intel, STMicroelectronics double the density of PCM

Intel and STMicroelectronics have developed a new type of PCM (phase-change memory) chip that doubles the memory density over previous versions, giving a boost to an emerging technology that could one day replace the flash memory chips widely used in portable devices.

The technology is still experimental, but the companies marked another step in its evolution, delivering samples of the new chips to device makers. Proponents say that PCM is more reliable than flash memory, and that it will offer faster data transfer speeds and be more durable.

PCM uses a glass-like material that can change from an amorphous, or gaseous, state to a crystalline state as its atoms are rearranged. The state of the material corresponds to the 1s and 0s in computing, allowing it to be used to store data.

As a result of their work, Intel and STMicro said the glass-like material can now be turned into four states instead of two, allowing it to retain twice the amount of data. The material can also exist in liquid and semi-liquid states.

The advances from Intel and STMicro have made the chips smaller and more power-efficient, said Guilio Casagrande, director of advanced research and development at STMicro.

Intel and STMicro presented their new developments on Wednesday at the International Solid States Circuits Conference in San Francisco.

Numerous other companies have also been working on PCM, also known as PRAM, including IBM, Qimonda, Macronix, Infineon and Samsung.

Phase-change memory has existed since the 1960s, but the cost of the technology and the energy required to drive change between one state and another was not competitive compared to other memory technologies like RAM and flash, said Cliff Smith, technology initiatives manager of Intel's flash group.

PCM has the potential to give fast read and write speeds, while the existing NOR flash type is slow to write and NAND flash is slow to read, Casagrande said. PCM could eventually replace existing memory technologies because of its power efficiency and its ability to reduce data leaks, Casagrande said.

Intel and STMicroelectronics signed a contract to develop PCM in 2003 and are in the process of establishing a flash-memory joint venture called Numonyx, due to launch by March 28. STMicro will hold a 48.6 percent stake of Numonyx, with Intel retaining 45.1 percent. The investment company Francisco Partners is also taking part.

Numonyx will manufacture existing flash memory types until PCM is ready for market, Smith said. He expects PCM to appear first in devices such as cell phones in two to three years. Its use will eventually overtake that of DRAM, NOR, and NAND flash, he said.