VP23-07 Monte Carlo Simulation on Spinterface’s Atomic Migration in SOT-MTJ Device
Creators: Yuhai Yuan; Yanfeng Jiang
Publisher: name: IEEE
Year: 2025

In recent years, as one of the most representative MTJ devices, spin orbit torque (SOT) MTJ is regarded as a key direction for the development of MRAM[1]. However, atomic diffusion and migration behaviors commonly occur at the heterojunction spinterfaces, which show obvious impact on the device and should be included in the characterizations of the device. In this study, an innovative computational approach that includes the migration of oxygen and metal atoms at the spinterfaces within SOT-MTJ is proposed. Here, the spinterfaces include the interface between the free layer (FL) and the oxide layer, as well as that between the FL and the heavy metal (HM) layer[2]. Utilizing Monte Carlo simulation, a simulation tool that models atomic migration at these heterojunctions is constructed. This tool innovatively applies the backward propagation of variance (BPV) technique[3] to both corner and statistical models, which is effective to link the electrical characteristics of SOT-MTJ device with the manufacturing process variations. Based on the simulation tool, it reveals the effect of the atomic migration on the electrical performance of the MTJ device. More specifically, the atomic mechanisms related to the substantial variability observed in Tunnel Magnetoresistance (TMR) values[4] of SOT-MTJ is discussed based on the simulation results, offering detailed insights at the atomic level into this pivotal phenomenon. This comprehensive understanding paves the way for improvements in SOT device reliability and performance.References: [1] Y. Wang, Y. Zhang, E. Y. Deng, J. O. Klein, L. A. B. Naviner, and W. S. Zhao, “Compact model of magnetic tunnel junction with stochastic spin transfer torque switching for reliability analyses,” Microelectron. Reliab., vol. 54, no. 9–10, pp. 1774–1778, Sep. 2014, doi: 10.1016/j.microrel.2014.07.019. [2] Z. Wang et al., “Atomic-Scale Structure and Local Chemistry of CoFeB–MgO Magnetic Tunnel Junctions,” Nano Lett., vol. 16, no. 3, pp. 1530–1536, Mar. 2016, doi: 10.1021/acs.nanolett.5b03627. [3] C. He, J. Victory, Y. Xiao, H. D. Vleeschouwer, E. Zheng, and Z. Hu, “SiC MOSFET Corner and Statistical SPICE Model Generation,” in 2020 32nd International Symposium on Power Semiconductor Devices and ICs (ISPSD), Vienna, Austria: IEEE, Sep. 2020, pp. 154–157. doi: 10.1109/ISPSD46842.2020.9170091. [4] Y. Ke, K. Xia, and H. Guo, “Oxygen-Vacancy-Induced Diffusive Scattering in Fe / MgO / Fe Magnetic Tunnel Junctions,” Phys. Rev. Lett., vol. 105, no. 23, p. 236801, Nov. 2010, doi: 10.1103/PhysRevLett.105.236801.
In recent years, as one of the most representative MTJ devices, spin orbit torque (SOT) MTJ is regarded as a key direction for the development of MRAM[1]. However, atomic diffusion and migration behaviors commonly occur at the heterojunction spinterfaces, which show obvious impact on the device and should be included in the characterizations of the device. In this study, an innovative computational approach that includes the migration of oxygen and metal atoms at the spinterfaces within SOT-MTJ is proposed. Here, the spinterfaces include the interface between the free layer (FL) and the oxide layer, as well as that between the FL and the heavy metal (HM) layer[2]. Utilizing Monte Carlo simulation, a simulation tool that models atomic migration at these heterojunctions is constructed. This tool innovatively applies the backward propagation of variance (BPV) technique[3] to both corner and statistical models, which is effective to link the electrical characteristics of SOT-MTJ device with the manufacturing process variations. Based on the simulation tool, it reveals the effect of the atomic migration on the electrical performance of the MTJ device. More specifically, the atomic mechanisms related to the substantial variability observed in Tunnel Magnetoresistance (TMR) values[4] of SOT-MTJ is discussed based on the simulation results, offering detailed insights at the atomic level into this pivotal phenomenon. This comprehensive understanding paves the way for improvements in SOT device reliability and performance.References: [1] Y. Wang, Y. Zhang, E. Y. Deng, J. O. Klein, L. A. B. Naviner, and W. S. Zhao, “Compact model of magnetic tunnel junction with stochastic spin transfer torque switching for reliability analyses,” Microelectron. Reliab., vol. 54, no. 9–10, pp. 1774–1778, Sep. 2014, doi: 10.1016/j.microrel.2014.07.019. [2] Z. Wang et al., “Atomic-Scale Structure and Local Chemistry of CoFeB–MgO Magnetic Tunnel Junctions,” Nano Lett., vol. 16, no. 3, pp. 1530–1536, Mar. 2016, doi: 10.1021/acs.nanolett.5b03627. [3] C. He, J. Victory, Y. Xiao, H. D. Vleeschouwer, E. Zheng, and Z. Hu, “SiC MOSFET Corner and Statistical SPICE Model Generation,” in 2020 32nd International Symposium on Power Semiconductor Devices and ICs (ISPSD), Vienna, Austria: IEEE, Sep. 2020, pp. 154–157. doi: 10.1109/ISPSD46842.2020.9170091. [4] Y. Ke, K. Xia, and H. Guo, “Oxygen-Vacancy-Induced Diffusive Scattering in Fe / MgO / Fe Magnetic Tunnel Junctions,” Phys. Rev. Lett., vol. 105, no. 23, p. 236801, Nov. 2010, doi: 10.1103/PhysRevLett.105.236801.