Though the company did not disclose the details, it said that the improvements were made to the material of the perpendicular magnetic memory element with a width of 30nm and its multilayer structure.
When the energy of the STT-MRAM using the new memory element in operation was calculated in a simulation, it was 46pJ. It is about 1/30 that of a traditional STT-MRAM and 1/3 (or less) that of SRAM, Toshiba said.
Furthermore, Toshiba made improvements to circuits. While its six-transistor SRAM and traditional STT-MRAM cache have a path for leakage current, the company developed a memory circuit that does not have a path for leakage current this time. The memory circuit has a three-transistor/one-MTJ structure and does not cause much leakage current in theory like DRAM, the company said.
As a result, it becomes possible to reduce the power consumption of cache memory to 1/3, according to Toshiba's estimate. The contribution of the normally-off operation and that of the improvement of the memory element are almost the same, the company said.
Toshiba also announced the results of a simulation for realizing a processor by using the new technologies. With an ARM core and Linux OS, it is possible to reduce power consumption to 1/3 that with a processor using an SRAM cache at the time of using an application while keeping the speed performance, according to the results.
Toshiba will announce three theses on STT-MRAM at the 2012 IEEE International Electron Devices Meeting (IEDM 2012). The lecture numbers of its reports on the memory element, the entire STT-MRAM and the circuit are 29.4, 11.3 and 10.5, respectively.
The latest results were achieved only by Toshiba, and SK Hynix Inc, which co-develops STT-MRAM with Toshiba, was not involved in the development, Toshiba said. The latest development was conducted in a project that the company carries out with New Energy and Industrial Technology Development Organization (NEDO).