Vol.2 No.3 2009

Research paper : Creating non-volatile electronics with spintronics technology (S. Yuasa et al.)−200−Synthesiology - English edition Vol.2 No.3 (2009) as simply builders of production systems, current production system manufacturers play the important role of developing new materials and new device production process technology in addition to building the systems. In this R & D, we aimed for a solution to the difficult problem described above by integrating AIST’s superior material and device technology seeds and the excellent production process technology and equipment possessed by the production system manufacturer (Fig. 10). In particular, the production sputtering system of that company is a world-standard system in the HDD industry, so if mass production technology can be developed using it, that technology can be rapidly transferred to the production lines of device manufacturers.In the joint research with the Canon ANELVA Corporation, we discovered that if amorphous CoFeB alloy is used for the lower ferromagnetic electrode, a high-quality oriented polycrystalline (textured) MgO (001) tunnel barrier layer can be grown over it at room temperature (Fig. 11(a))[13]. A CoFeB/MgO/CoFeB structure MTJ device that uses this very special manner of crystal growth can be fabricated over any base layer because the lower electrode layer is amorphous. Moreover, it is formed by room temperature sputtering, so it is ideal in terms of production process compatibility and production efficiency. When that CoFeB/MgO/CoFeB-MTJ device is heat-treated at 250 or above, crystallization of the amorphous CoFeB layer begins from the interfaces (Fig. 11), and a bcc CoFeB(001) structure that has good lattice matching with the MgO (001) layer forms[14]. The device structure shown in Fig. 11(b) is basically the same as the single-crystal MgO-MTJ device and the oriented polycrystalline MgO-MTJ device, so giant TMR effect manifests by the same physical mechanism (Fig. 9, 4))[13]. This thin film fabrication process is an original method that counters the common-sense understanding that crystal growth proceeds upwards from the base layer.That CoFeB/MgO/CoFeB MTJ device has now become the mainstream technology in spintronics applications, and various types of vigorous R & D that use it are proceeding on a worldwide scale. That work has so far achieved a room temperature giant MR ratio of 600 %. Incidentally, success in developing the CoFeB/MgO/CoFeB-MTJ device was achieved in barely one year from the beginning of the joint research with Canon ANELVA. That achievement was largely dependent on the “good lineage” of the crystalline MgO tunnel barrier, but it also verified that the combination of AIST and a production system manufacturer engaging in Type 2 Basic Research was a highly suitable approach.3 Creating Outcomes3.1 Commercialization of the ultra-high-density MgO-TMR HDD headThe CoFeB/MgO/CoFeB MTJ device developed jointly by AIST and the Canon ANELVA Corporation and that company’s production system were quickly introduced to HDD manufacturers’ product development lines and energetically used in mass production of HDD magnetic heads (Fig. 10). The result of vigorous product development was the successful commercialization of the second-generation TMR head (MgO-TMR head) using the MgO-MTJ device by various HDD manufacturers in 2007. The MgO-TMR head had greatly higher performance than the Fig.10 Full Research on MgO-MTJ device.ProductdevelopmentUniversityDevicemanufacturersAISTAISTMBE system forbasic researchDevelopment of newmaterials and devicesBasic materialanddevice technologyDevicemanufacturersMass productiontechnologyProduction systemmanufacturerManufacturingsystemsType 1 BasicResearchHard diskNon-volatile memorySingle-crystalMgO-MTJ deviceClose cooperation NEDO-PjDevelopment of massproduction technologyCoFeB/MgO/CoFeBMTJ deviceLarge siliconsubstrateProduction sputteringsystemSpecialsingle-crystalsubstrateType 2 BasicResearchProductionsystemmanufacturerOne wafer per day100 wafers per day“Valley of death”


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