Phase Change Technology Big for Memory, ST Says

By David Manners -- Electronics Weekly, 6/9/2006

STMicroelectronics has a flash technology roadmap going all the way down to 32nm with phase change technology coming into the product line along with the traditional floating gate technology at the 45nm process node.

“We think phase change will be a big engine for the next generation of memories,” said Laurent Bosson, VP for manufacturing and technology at ST.

The floating gate roadmap is scheduled to go down to 45nm. At the moment the production process is 70nm for NAND and 90nm for NOR, with 60nm NAND and 65nm NOR both scheduled to move into production this year.

Next year ST intends to move NOR to 45nm and NAND to 50nm, and in 2008 NAND is scheduled to go to 42nm. “We’re pushing the limits at 45nm,” said Bosson.

That is when it is hoped that phase change will kick in though ST is not planning volume production of phase change memories before 2008 and, according to Orio Bellezza, group VP for advanced R&D in non-volatile memories at ST: “We expect to come in at 1Gbit or 500Mbit.”

That is a density level which is well below the 8Gbit leading edge floating point flash memories being produced today. ST has produced a 128Mbit 90nm phase change demonstrator chip.

ST’s NOR flash manufacturing is currently being done at its Singapore, Catania and Agrate fabs. Its NAND flash comes out of its 8-inch joint venture fab owned jointly with Hynix. The joint venture’s first 300mm fab is scheduled to be completed by Q3 and to start production in Q4.

ST licensed its phase change technology from Ovonyx, a subsidiary of Energy Conversion Devices, whose chief scientist, Stan Ovshinsky, has been working on phase change memory technology based on chalcogenides since the 1950s.

Electronics Weekly is the London-based sister publication of Electronic News.