Partnership Yields stable, Low-Power Memory Cell Structure

The joint efforts of Hitachi and Renesas Technology converge in a unique memory-cell technology that promises stable fabrication of phase-change memory while maintaining low-power operation. The technology involves forming an interfacial layer of tantalum pent-oxide between the plug that connects to a MOS transistor and the phase-change film. This also requires optimizing the thickness of the interfacial layer. The layer prevents heat diffusion from the phase-change film via the plug, resulting in a rapid temperature rise in the phase-change film. Therefore, the melting point is reached using less power. Phase-change memory cell prototypes employing this structure exhibit a power consumption of 100 µA at a supply voltage of 1.5V during programming and the ability to withstand 100 million rewrites. In addition, the resistance variation in the wafer is limited, with a ratio in two digits between the high and low resistance values. HITACHI AMERICA LTD., Brisbane, CA. (800) 448-2244. RENESAS TECHNOLOGY AMERICA INC., San Jose, CA. (408) 382-7407.