LONDON STMicroelectronics is backing phase-change memory as the technology most likely to succeed flash memory, and could move its development work to volume manufacture in the 45-nm process generation. The company currently has a 128-Mbit large area demonstrator implemented on 90-nanometer process technology.
Laurent Bosson, executive vice president in charge of technology and manufacturing at ST, showed the company’s latest phase-change roadmap to financial analysts at a conference held here on Tuesday (May 22). Volume production of a multigigabit phase change memory is expected to arrive at the 45- or 32-nm node, some time after 2008, according to Bosson.
The large array demonstrator has been build after simple proof-of-concept circuits were developed by ST over the period 2002 to 2004. With the principle of operation proved out the 128-Mbit device is being used to determine product performance, manufacturability, scalability and cost. This is intended to help the memory technology intersect with leading-edge manufacturing and provide a system-level benefit to customers Bosson said.
Carlo Bozotti, now chief executive but then general manager of the memory product group, signaled the entry into the large area demonstrator phase in May 2004. Back then Bozotti envisioned moving phase change memory to customer sampling before the end of 2005. In contrast Bosson put samples somewhere well beyond 2006.
ST’s investigation of phase-change memory is based on a licensing agreement with Ovonyx Inc., a wholly-owned subsidiary of Energy Conversion Devices Inc., which was set up to work with ST and Intel. Ovonic Unified Memory attempts to exploit a reversible phase change between the amorphous and crystalline states that can be affected in chalcogenide alloys, typically an alloy of antimony telluride and germanium telluride.