FR-03 Anomalous Hall Resistance in Ta/Co40Fe40B20/MgO/Ta for Constructing Physical Unclonable Function
Creators: Divyanshu Divyanshu
Meng Tang
Aijaz H. Lone
Selma Amara
and Gianluca Setti
Publisher: name: IEEE
Year: 2025

Physical Unclonable Functions (PUFs) enhance device authenticity and resist cloning by generating unique identifiers. Spintronics-PUF devices, with key advantages for hardware security, have gained significant interest [1]-[4]. In this work, we experimentally demonstrate Ta (5nm)/ Co40Fe40B20 (0.85nm)/ MgO (2nm)/ Ta (2nm) Hall bar devices as spintronic PUFs, considering process-induced device-to-device (D2D) variation in the critical spin-orbit torque (SOT) switching current. PUF tokens are fabricated under similar conditions to account for actual process variation during the fabrication process. The single PUF token size is 510 µm*510 µm. The anomalous Hall effect loops and the current-induced magnetization switching loops demonstrate good perpendicular magnetic anisotropy (PMA) and D2D variation. Fig 1 shows the detailed block diagram of the setup used. Measurements were performed in a magnetic field environment at room temperature. A constant DC read current of 60 µA is used. A fixed write current of ±1.72 mA, Hx = +400 Oe, for this setup, is used to generate the challenge-response (CRP) pairs. Obtained anomalous Hall resistance (RH) is converted into response bits, which include appropriate normalization and offset. The challenge set consists of 300 bits in matrix form, and the corresponding response set consists of 300 bits. The obtained CRP data set is then evaluated for PUF performance metrics using Python and NIST SP 800-22 statistical suit. Several key PUF performance metrics are calculated, as shown in Fig 2. Our results indicate good performance in terms of uniformity (45.167%), response complexity, and repeatability for the selected main PUF tokens. However, the obtained uniqueness value is inferior due to the chosen biasing point. Overall, this work demonstrates a promising initial performance for spintronic PUFs, which can be further optimized.References: [1] S. Gosh, Proc. IEEE Inst. Electr. Electron. Eng., vol. 104, no. 10, pp. 1864–1893 (2016). [2] G. Finocchio et al., J. Appl. Phys., vol. 128, no. 3, p. 033904 (2020). [3] D. Divyanshu, et. al, IEEE Access, vol. 10, pp. 93029–93038 (2022). [4] S. Zhang et al., Sci. China Inf. Sci., vol. 65, no. 2 (2022).
Physical Unclonable Functions (PUFs) enhance device authenticity and resist cloning by generating unique identifiers. Spintronics-PUF devices, with key advantages for hardware security, have gained significant interest [1]-[4]. In this work, we experimentally demonstrate Ta (5nm)/ Co40Fe40B20 (0.85nm)/ MgO (2nm)/ Ta (2nm) Hall bar devices as spintronic PUFs, considering process-induced device-to-device (D2D) variation in the critical spin-orbit torque (SOT) switching current. PUF tokens are fabricated under similar conditions to account for actual process variation during the fabrication process. The single PUF token size is 510 µm*510 µm. The anomalous Hall effect loops and the current-induced magnetization switching loops demonstrate good perpendicular magnetic anisotropy (PMA) and D2D variation. Fig 1 shows the detailed block diagram of the setup used. Measurements were performed in a magnetic field environment at room temperature. A constant DC read current of 60 µA is used. A fixed write current of ±1.72 mA, Hx = +400 Oe, for this setup, is used to generate the challenge-response (CRP) pairs. Obtained anomalous Hall resistance (RH) is converted into response bits, which include appropriate normalization and offset. The challenge set consists of 300 bits in matrix form, and the corresponding response set consists of 300 bits. The obtained CRP data set is then evaluated for PUF performance metrics using Python and NIST SP 800-22 statistical suit. Several key PUF performance metrics are calculated, as shown in Fig 2. Our results indicate good performance in terms of uniformity (45.167%), response complexity, and repeatability for the selected main PUF tokens. However, the obtained uniqueness value is inferior due to the chosen biasing point. Overall, this work demonstrates a promising initial performance for spintronic PUFs, which can be further optimized.References: [1] S. Gosh, Proc. IEEE Inst. Electr. Electron. Eng., vol. 104, no. 10, pp. 1864–1893 (2016). [2] G. Finocchio et al., J. Appl. Phys., vol. 128, no. 3, p. 033904 (2020). [3] D. Divyanshu, et. al, IEEE Access, vol. 10, pp. 93029–93038 (2022). [4] S. Zhang et al., Sci. China Inf. Sci., vol. 65, no. 2 (2022).