Insert Layer for Spin Orbit Torque Magnetic Memory
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Solution Overview
Problem
Spintronic memory technologies, such as STT-MRAM, face challenges with high voltage and current requirements during programming, leading to reliability issues and slow switching times due to large write currents and high write error rates in magnetic tunnel junctions.
Innovation Solution
Incorporating inserts like Hf, Ta, W, Ir, Pt, Bi, Cu, Mo, Gd, Ge, Ga, or Au between the spin orbit coupling (SOC) or spin orbit torque (SOT) layer and the free magnet layer in magnetic junctions, which reduce the DMI at the interface and act as a matching layer to enhance spin orbit coupling efficiency, allowing for lower power and faster switching with perpendicular magnetization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If spin transfer torque based magnetic random access memory is used, then state retention and energy efficiency are enabled, but high voltage and high write current are required during programming
Solution Approach 1:
A non-magnetic insert layer (Ru, Rh, Ir, Cu, Ag, Au, Al, or their alloys) is introduced as an intermediary between the magnetic tunnel junction and the spin orbit coupling electrode. This insert layer mediates the interaction between the spin-polarized current and the free magnet layer, enabling more efficient spin transfer torque switching with reduced write current requirements while maintaining energy efficiency.
Solution Approach 2:
The patent employs a composite structure combining magnetic tunnel junction materials (CoFeB, CoFe) with non-magnetic insert materials (Ru, Rh, Ir, Cu, Ag, Au, Al) and spin orbit coupling materials (Pt, Pd, Ir). This composite material approach optimizes the spin transfer torque effect by combining the advantages of different materials to achieve lower write current while maintaining state retention and energy efficiency.
2Productivity
If large write current is applied to write a tunnel junction based magnetic tunnel junction, then switching can be achieved, but reliability issues arise due to the presence of large current flowing through the tunnel barrier
Solution Approach 1:
The non-magnetic insert layer serves as a protective intermediary that reduces the direct impact of high write current on the tunnel barrier. By introducing this intermediate layer, the current density through the tunnel barrier is reduced, preventing damage and reliability degradation while still enabling effective magnetization switching through enhanced spin transfer torque.
Solution Approach 2:
The patent replaces the direct high-current switching mechanism with a spin transfer torque-based switching mechanism. Instead of relying on high current flowing directly through the tunnel junction, the system uses spin-polarized current in the insert layer to exert torque on the free magnet layer, achieving switching with lower current and improved reliability.
3Power
If limited write current is used in MTJ based MRAM, then write error rates increase or switching times exceed 20 ns
Solution Approach 1:
The composite structure of magnetic tunnel junction materials combined with non-magnetic insert materials and spin orbit coupling materials creates an optimized system where spin transfer torque is enhanced. This material combination enables fast switching times (below 20 ns) with reduced write current by improving the efficiency of angular momentum transfer from spin-polarized electrons to the free magnet layer.
Solution Approach 2:
The patent changes key parameters including the insertion of non-magnetic layers with specific thicknesses (1-10 nm), use of materials with high spin polarization, and optimization of tunnel barrier properties. These parameter changes enable the system to achieve fast switching speeds with lower write current by optimizing the spin transfer torque efficiency and reducing damping effects.
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 approach enables low programming voltages, reduces write error rates, and achieves faster switching times of less than 10 ns with significantly lower read currents, improving the reliability of magnetic tunnel junctions and enabling efficient spin orbit torque-based magnetic memory.
Implementation Method 1
spin orbit torque based magnetic memory
Implementation Method 2
spin hall effect or spin orbit torque electrode
Implementation Method 3
reduce the DMI at the interface
Data Source
AI summary
An apparatus is provided which comprises: a magnetic junction having a magnet with a first magnetization (e.g., perpendicular magnetization); a first structure adjacent to the magnetic junction, wherein the first structure comprises metal (e.g., Hf, Ta, W, Ir, Pt, Bi, Cu, Mo, Gf, Ge, Ga, or Au); an interconnect adjacent to the first structure; and a second structure adjacent to the interconnect such that the first structure and the second structure are on opposite surfaces of the interconnect, wherein the second structure comprises a magnet with a second magnetization (e.g., in-plane magnetization) substantially different from the first magnetization.