“…The change in resistance is consistent between R-H and R-V loops, and corresponds to a TMR of 150% with a low RA of 3.5 Ω·μm 2 . Note this is not the highest reported TMR for the ultrathin CFB free layer as we have recently reported TMR greater than 180% for a similar structure with a slightly higher RA 12 .Figure 6Room temperature device switching characteristics. ( a ) Resistance versus applied magnetic field and ( b ) resistance versus DC voltage (1 ms pulses) curves from a nominal 30 nm device.…”
Section: Resultsmentioning
confidence: 91%
“…However, as Δ assumes a perfect patterning process in which the cylindrical MTJ pillars incur no damage, the estimated values represent the upper limit for Δ. A previously reported study finds Δ MS = 59 at 25 °C and the difference between the estimated Δ and experimental Δ is attributed to MTJ pillar damage incurred during fabrication 12 .Figure 5Simulated thermal stability factor Δ for different device diameters under macrospin and domain wall reversal models.…”
Section: Resultsmentioning
confidence: 94%
“…Here, we report the use of an Mg insertion layer within an ultrathin CoFeB layer that gives rise to PMA. The device performance of this ultrathin free layer was recently reported as it achieved breakthroughs in low magnetic moment and low damping that gave rise to ultra-low voltage and ultra-low power devices 11,12 . In this work, we show that the achievement of ultrathin CoFeB layers are of technological importance as they fulfill the requirements for reversal of the free layer magnetization at short pulse lengths below 10 ns, and at deep error rates of less than 1 ppm which are essential to applications such as last level cache that use static random access memory technology.…”
Section: Introductionmentioning
confidence: 99%
“…These free layers can exhibit good thermal stability withstanding 400 °C back end of line process temperatures and a wide range of operating temperatures, but require a high switching voltage. By contrast, the conservation of spin angular momentum argues that a lower moment free layer is important for the design of low switching voltage magnetic random access memory (MRAM) devices 12,16 . This study shows that ultrathin, thermally stable, high saturation magnetization CFB free layers can be achieved with the incorporation of Mg, enabling a low switching voltage at short pulse lengths.…”
Perpendicular magnetic anisotropy (PMA) ferromagnetic CoFeB with dual MgO interfaces is an attractive material system for realizing magnetic memory applications that require highly efficient, high speed current-induced magnetic switching. Using this structure, a sub-nanometer CoFeB layer has the potential to simultaneously exhibit efficient, high speed switching in accordance with the conservation of spin angular momentum, and high thermal stability owing to the enhanced interfacial PMA that arises from the two CoFeB-MgO interfaces. However, the difficulty in attaining PMA in ultrathin CoFeB layers has imposed the use of thicker CoFeB layers which are incompatible with high speed requirements. In this work, we succeeded in depositing a functional CoFeB layer as thin as five monolayers between two MgO interfaces using magnetron sputtering. Remarkably, the insertion of Mg within the CoFeB gave rise to an ultrathin CoFeB layer with large anisotropy, high saturation magnetization, and good annealing stability to temperatures upwards of 400 °C. When combined with a low resistance-area product MgO tunnel barrier, ultrathin CoFeB magnetic tunnel junctions (MTJs) demonstrate switching voltages below 500 mV at speeds as fast as 1 ns in 30 nm devices, thus opening a new realm of high speed and highly efficient nonvolatile memory applications.
“…The change in resistance is consistent between R-H and R-V loops, and corresponds to a TMR of 150% with a low RA of 3.5 Ω·μm 2 . Note this is not the highest reported TMR for the ultrathin CFB free layer as we have recently reported TMR greater than 180% for a similar structure with a slightly higher RA 12 .Figure 6Room temperature device switching characteristics. ( a ) Resistance versus applied magnetic field and ( b ) resistance versus DC voltage (1 ms pulses) curves from a nominal 30 nm device.…”
Section: Resultsmentioning
confidence: 91%
“…However, as Δ assumes a perfect patterning process in which the cylindrical MTJ pillars incur no damage, the estimated values represent the upper limit for Δ. A previously reported study finds Δ MS = 59 at 25 °C and the difference between the estimated Δ and experimental Δ is attributed to MTJ pillar damage incurred during fabrication 12 .Figure 5Simulated thermal stability factor Δ for different device diameters under macrospin and domain wall reversal models.…”
Section: Resultsmentioning
confidence: 94%
“…Here, we report the use of an Mg insertion layer within an ultrathin CoFeB layer that gives rise to PMA. The device performance of this ultrathin free layer was recently reported as it achieved breakthroughs in low magnetic moment and low damping that gave rise to ultra-low voltage and ultra-low power devices 11,12 . In this work, we show that the achievement of ultrathin CoFeB layers are of technological importance as they fulfill the requirements for reversal of the free layer magnetization at short pulse lengths below 10 ns, and at deep error rates of less than 1 ppm which are essential to applications such as last level cache that use static random access memory technology.…”
Section: Introductionmentioning
confidence: 99%
“…These free layers can exhibit good thermal stability withstanding 400 °C back end of line process temperatures and a wide range of operating temperatures, but require a high switching voltage. By contrast, the conservation of spin angular momentum argues that a lower moment free layer is important for the design of low switching voltage magnetic random access memory (MRAM) devices 12,16 . This study shows that ultrathin, thermally stable, high saturation magnetization CFB free layers can be achieved with the incorporation of Mg, enabling a low switching voltage at short pulse lengths.…”
Perpendicular magnetic anisotropy (PMA) ferromagnetic CoFeB with dual MgO interfaces is an attractive material system for realizing magnetic memory applications that require highly efficient, high speed current-induced magnetic switching. Using this structure, a sub-nanometer CoFeB layer has the potential to simultaneously exhibit efficient, high speed switching in accordance with the conservation of spin angular momentum, and high thermal stability owing to the enhanced interfacial PMA that arises from the two CoFeB-MgO interfaces. However, the difficulty in attaining PMA in ultrathin CoFeB layers has imposed the use of thicker CoFeB layers which are incompatible with high speed requirements. In this work, we succeeded in depositing a functional CoFeB layer as thin as five monolayers between two MgO interfaces using magnetron sputtering. Remarkably, the insertion of Mg within the CoFeB gave rise to an ultrathin CoFeB layer with large anisotropy, high saturation magnetization, and good annealing stability to temperatures upwards of 400 °C. When combined with a low resistance-area product MgO tunnel barrier, ultrathin CoFeB magnetic tunnel junctions (MTJs) demonstrate switching voltages below 500 mV at speeds as fast as 1 ns in 30 nm devices, thus opening a new realm of high speed and highly efficient nonvolatile memory applications.
“…Experimentally, the most advanced STT-MTJ now can achieve 1 ns switching with a current density of 10-20 MA/cm 2 in sub-50nm perpendicular magnetic tunnel junctions (MTJs). [1,2] While the best SOT-MTJ at the research front now can already achieve 0.5 ns switching with a current density of 10-20 MA/cm 2 in sub-500nm in-plane MTJs. [3][4][5] When scaled-down, in-plane SOT-MTJ can potentially achieve sub-ns, and ~fJ write operation.…”
As spin-orbit-torque magnetic random-access memory (SOT-MRAM) is gathering great interest as the nextgeneration low-power and high-speed on-chip cache memory applications, it is critical to analyze the magnetic tunnel junction (MTJ) properties needed to achieve sub-ns, and ~fJ write operation when integrated with CMOS access transistors. In this paper, a 2T-1MTJ cell-level modeling framework for in-plane type Y SOT-MRAM suggests that high spin Hall conductivity and moderate SOT material sheet resistance are preferred. We benchmark write energy and speed performances of type Y SOT cells based on various SOT materials experimentally reported in the literature, including heavy metals, topological insulators and semimetals. We then carry out detailed benchmarking of SOT material Pt,-W, and BixSe(1-x) with different thickness and resistivity. We further discuss how our 2T-1MTJ model can be expanded to analyze other variations of SOT-MRAM, including perpendicular (type Z) and type X SOT-MRAM, two-terminal SOT-MRAM, as well as spin-transfer-torque (STT) and voltagecontrolled magnetic anisotropy (VCMA)-assisted SOT-MRAM. This work will provide essential guidelines for SOT-MRAM materials, devices, and circuits research in the future.
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