On January 28th, 2022, the research team of the New principles Computing Research Center of the National Research and Development Corporation Industrial Technology Comprehensive Institute developed a new magnetic tunnel junction element (MTJ element) using a tunnel barrier layer composed of lithium fluoride (LiF) and magnesium oxide (MgO). It announces that it has successfully greatly improved the record retention characteristics of magnetic memory (MRAM). The General Industry Research Institute believes that this is a technology that is expected to be used in memory for brain computing.
The MTJ element has a structure that clamps the tunnel barrier layer of about 1 nm with a magnetic film, and the information can be stored semi-permanently according to the magnetization direction of the magnetic film. If this feature is used, the non-volatile memory that does not require standby power becomes possible, and it is expected to be used in brain-type computing that mimics the structure and information processing of the brain for high information processing.
However, the magnetization direction of MTJ elements sometimes fluctuates due to room temperature or heat in operation, and the information disappears. Therefore, in order to maintain the recorded information reliably, it is necessary to maintain the direction of magnetization in a specific direction without affecting the heat.
The research team developed a new structural MTJ element using a composite tunnel barrier layer of LiF and MgO. By introducing a very thin LiF with only one or two atomic layers between the iron (Fe) and MgO in the recording layer, it is found that the magnetization direction of Fe is stable in the direction perpendicular to the film surface. It is also confirmed that compared with the existing MTJ elements whose tunnel barrier layer is MgO single layer, the record holding characteristic is improved by about 2 times. If this technology is applied, even the voltage writing type MRAM with thin recording layer can achieve high record holding characteristics.
In the future, in order to realize the gigabit voltage writing MRAM which is expected to be a powerful candidate for brain computing memory, the material / structure design including base layer and magnetic layer materials is discussed. While further improving the performance, the development of voltage writing technology will also be promoted.
The technical details will be published online in the academic journal NPG Asia Materials on January 28, 2022.
Press release: press release