SOT-MRAM Device Field-Free Magnetization Switching
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Solution Overview
Problem
Current magnetoresistive random access memory (MRAM) devices face challenges in reducing power consumption and achieving efficient data writing, particularly in spin orbit torque-magnetoresistive memory (SOT-MRAM) devices, where existing technologies struggle to effectively utilize spin currents for magnetization switching without external magnetic fields.
Innovation Solution
The proposed SOT-MRAM device incorporates a spin orbit torque structure with a stack of a metal oxide layer, a horizontal ferromagnetic pattern, and a non-magnetic pattern, generating vertical spin currents through the spin Hall effect, which are used to induce magnetization switching in a free layer pattern within a magnetic tunnel junction (MTJ) structure, allowing for field-free magnetization switching and reduced operating currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional MRAM devices use traditional write mechanisms, then data writing can be achieved, but power consumption is high and efficiency is low
Solution Approach 1:
The patent replaces conventional current-driven magnetization switching with spin orbit torque-based switching. By utilizing the spin Hall effect in a non-magnetic metal layer, the invention converts charge current into spin current, which then exerts torque on the ferromagnetic layer to switch magnetization. This substitution of the write mechanism achieves lower power consumption and higher writing efficiency compared to traditional methods.
Solution Approach 2:
The patent introduces a horizontal magnetic field component through the ferromagnetic pattern's in-plane magnetization, which modifies the switching conditions. By combining this horizontal field with the vertical spin torque from the spin Hall effect, the device achieves asymmetric switching thresholds and improved writing efficiency while reducing the required current density for magnetization reversal.
2Device complexity
If spin currents are used for magnetization switching without external magnetic fields, then device integration is improved, but effective utilization of spin currents is challenging
Solution Approach 1:
The patent employs a composite structure consisting of a non-magnetic metal layer (providing spin Hall effect), a ferromagnetic layer (providing magnetization), and an oxide layer (providing interface spin current). This composite material system enables reliable field-free magnetization switching by combining multiple physical effects at the nanoscale interface, achieving both integration compatibility and switching reliability.
Solution Approach 2:
The ferromagnetic pattern with horizontal magnetization serves as an intermediary that converts the vertical spin torque from the spin Hall effect into effective switching action. The in-plane magnetization creates a horizontal magnetic field component that, when combined with the spin torque, enables reliable magnetization switching without requiring external magnetic fields, thus mediating between the spin current source and the storage layer.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration enhances data writing efficiency by increasing interface spin currents, reducing the threshold currents required for magnetization switching and decreasing operating currents in the SOT-MRAM device, thereby improving power efficiency and data writing characteristics.
Implementation Method 1
the spin currents include a spin current generated by a spin Hall effect
Implementation Method 2
a first interface spin current generated at a first interface between the oxide layer pattern and the ferromagnetic pattern
Implementation Method 3
a second interface spin current generated at a second interface between the ferromagnetic pattern and the non-magnetic pattern
Implementation Method 4
magnetoresistive random access memory device
Data Source
AI summary
A magneto resistive random access memory (MRAM) device including a spin orbit torque structure including a stack of an oxide layer pattern, a ferromagnetic pattern, and a non-magnetic pattern; and a magnetic tunnel junction (MTJ) structure on the spin orbit torque structure, the MTJ structure including a stack of a free layer pattern, a tunnel barrier pattern, and a pinned layer pattern, wherein the spin orbit torque structure extends in a first direction parallel to an upper surface of the spin orbit torque structure, the ferromagnetic pattern includes a horizontal magnetic material, and the free layer pattern has a magnetization direction in a vertical direction perpendicular to the upper surface of the spin orbit torque structure, the magnetization direction being changeable in response to spin currents generated in the spin orbit torque structure.