New Phase-change Memory Superior in Speed, Efficiency, Cycling Capability

Dec 10, 2013
Jyunichi Oshita, Nikkei BP Semiconductor Research

Low-power Electronics Association & Project (LEAP) and the University of Tsukuba announced that they have co-developed a phase-change memory technology using a new film structure and operating principles at IEDM 2013 (lecture number: 30.5).

Compared with existing phase-change memories, the new technology reduces write time and writing current by 90% or more and increases cycling capability to 100 million (108) times or more.

"We aim to commercialize the new technology by 2018 to 2020, when new memory technologies are required for SSDs designed for data centers due to 'information explosion'," said Norikatsu Takaura, the Phase-Change Device Group, LEAP.

At the 2013 Symposium on VLSI Technology, which took place in June 2013, the development team announced a phase-change memory technology that replaces a conventional GeSbTe-based phase-change film with a superlattice film using GeTe/Sb2Te3.

The GeSbTe film of conventional phase-change memory is melted by heat, changing the resistance value of the film. On the other hand, with the newly-developed structure, resistance value is changed by the movement of Ge ions caused by electron injection. As a result, compared with NAND flash memories used for current SSDs and conventional phase-change memories, the new technology enables to rewrite data at a higher speed and with a lower power consumption.

At the 2013 Symposium on VLSI Technology, the team announced that it became possible to halve the rewriting voltage of phase-change memory to 0.4V. This time, it enhanced film quality by changing the conditions for the formation of the GeTe/Sb2Te3 superlattice film. As a result, the team drastically improved memory properties such as cycling capability and rewriting current.