SOT MRAM Cell with Angled Bottom Plugs for Field-Free Write
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Solution Overview
Problem
Current magnetic random access memories (MRAMs) require external magnetic fields for high write speed, which complicates production and application, and have limitations in read-write speed and magnetic moment reversal.
Innovation Solution
A magnetic random access memory cell design featuring a spin-orbit torque (SOT) layer with a magnetic tunnel junction and strategically positioned bottom plugs forming an acute angle with the magnetic moment direction, allowing both parallel and perpendicular magnetic moment components to the write current, enabling faster read-write speeds and magnetic moment reversal without external magnetic fields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If external magnetic fields are used to achieve high write speed, then write speed is improved, but device complexity and production difficulty increase
Solution Approach 1:
The patent extracts and eliminates the external magnetic field component from the write operation. By designing the SOT layer with bottom plugs forming an acute angle with the magnetic moment direction, the spin-orbit torque alone can reverse the magnetic moment without requiring external magnetic fields, thus simplifying the device structure and production process while maintaining high write speed
Solution Approach 2:
The patent changes the geometric parameters of the SOT layer structure by positioning bottom plugs at an acute angle relative to the magnetic moment direction. This parameter change enables the spin-orbit torque to effectively reverse the magnetic moment through in-plane current flow, achieving high write speed without external magnetic fields and reducing device complexity
2Speed
If separate paths for read and write are implemented, then read-write speed and stability are improved, but device structure becomes more complex
Solution Approach 1:
The patent segments the current paths into separate read and write paths. The write current flows through the SOT layer via bottom plugs to generate spin-orbit torque for magnetic moment reversal, while the read current flows perpendicularly through the magnetic tunnel junction for data reading. This segmentation enables high read-write speed and stability while the compact three-terminal MTJ structure minimizes overall device complexity
3Ease of operation
If write current flows through the SOT layer to reverse magnetic moment, then magnetic moment reversal is achieved, but read-write speed and performance need further improvement
Solution Approach 1:
The patent introduces asymmetry in the SOT layer structure by positioning bottom plugs at an acute angle with respect to the magnetic moment direction. This asymmetric configuration optimizes the spin-orbit torque efficiency, enabling faster magnetic moment reversal and improving read-write speed while maintaining ease of magnetic moment reversal through in-plane current flow
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 design enhances read-write speed and simplifies the MRAM structure by allowing magnetic moment reversal within the SOT layer, improving performance and reducing production complexity.
Implementation Method 1
The so-called 'nonvolatile' means that the memory can be kept intact after the power to the memory is turned off. An MRAM device has a high-speed read/write capability of a static random access memory (SRAM) and the high integration of a dynamic random access memory (DRAM), and can generally be rewritten infinitely.
Implementation Method 2
A spin-orbit torque (SOT) refers to the generation of a spin transfer torque using a charge flow-induced spin current based on spin-orbit coupling (SOC) to regulate the magnetic memory cells.
Implementation Method 3
The read current of the SOT MRAM perpendicularly passes through the magnetic tunnel junction (MTJ), but the write current, relying on the current flowing in the material parallel to and adjacent to the free layer, drives the torque generated by the spin orbit effect on their interface to reverse the magnetic moment of the free layer.
Data Source
AI summary
Provided are a magnetic random access memory cell and a magnetic random access memory. In one form, a memory cell includes: a spin-orbit torque (SOT) layer, through which a write current flows when performing a write operation on the magnetic random access memory cell; a magnetic tunnel junction, located on the SOT layer; a first bottom plug, located on a bottom of the SOT layer and contacting one end of the SOT layer, and a second bottom plug, located on the bottom of the SOT layer and spaced apart from the first bottom plug, the second bottom plug contacting the other end of the SOT layer, and an arrangement direction of the second bottom plug and the first bottom plug forming an acute included angle with a magnetic moment direction of the magnetic tunnel junction.