SOT-MRAM Stack With Magnetic Bias Layer for Field-Free Writing
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Solution Overview
Problem
Conventional spin-orbit torque (SOT)-based magnetoresistive random access memory (MRAM) devices require an external magnetic field for writing, complicating the process and reducing switching efficiency.
Innovation Solution
Incorporating a magnetic bias layer with perpendicular magnetic anisotropy in contact with the SOT layer, which breaks the symmetry of charge carriers, allowing magnetization reversal without an external field, thus simplifying the process and improving switching efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional SOT-based MRAM devices use external magnetic field for writing, then magnetization reversal can be achieved, but the process becomes complicated and switching efficiency is reduced
Solution Approach 1:
The patent extracts and removes the external magnetic field component from the writing process by incorporating a magnetic bias layer that generates the necessary magnetic field internally. This eliminates the need for external magnetic field application equipment and simplifies the writing process while maintaining magnetization reversal capability.
Solution Approach 2:
The magnetic bias layer serves the system by providing the necessary magnetic field for magnetization reversal internally. The bias layer automatically compensates for the lack of external magnetic field, enabling the device to perform the writing function autonomously without external assistance.
2Productivity
If magnetic bias layer with perpendicular magnetic anisotropy is incorporated, then switching efficiency is improved, but device structure becomes more complex
Solution Approach 1:
The patent combines the magnetic bias layer with the existing spin-orbit torque layer and magnetic tunnel junction structure. By merging these components into a unified stack, the device achieves improved switching efficiency while minimizing the increase in structural complexity through integrated design.
Solution Approach 2:
The magnetic bias layer serves multiple functions: it provides the necessary magnetic field for magnetization reversal, establishes perpendicular magnetic anisotropy for efficient switching, and maintains compatibility with standard MRAM read operations. This multi-functionality justifies the additional layer by delivering multiple benefits from a single structural addition.
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 enables external field-free SOT-MRAM operation, enhancing switching current efficiency and maintaining a sufficient reading window, thereby boosting device performance.
Implementation Method 1
spin-orbit torque (SOT)-based magnetoresistive random access memory (MRAM) devices
Implementation Method 2
The conductive lines sandwich a magnetic tunnel junction (MTJ), which functions as a magnetic memory cell
Data Source
AI summary
Memory stacks, memory devices and method of forming the same are provided. A memory stack includes a spin-orbit torque layer, a magnetic bias layer and a free layer. The magnetic bias layer is in physical contact with the spin-orbit torque layer and has a first magnetic anisotropy. The free layer is disposed adjacent to the spin-orbit torque layer and has a second magnetic anisotropy perpendicular to the first magnetic anisotropy.