SOT-MRAM Element Segmented Voltage Path for Fast Read Speed
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Solution Overview
Problem
In SOT-MRAM elements, the integration of multiple MTJs for high-speed and high-rewrite resistance is hindered by the need to apply a voltage during writing, leading to increased resistance and slowed read operations due to thickened insulating layers for voltage withstand, which results in a trade-off between fast write and slow read times.
Innovation Solution
A magnetoresistance effect element design featuring a heavy metal layer with a magnetic recording unit and insulating layer configuration that allows magnetization reversal through a write current flowing between the heavy metal layer and the insulating layer, without current flow to the recording unit during writing, reducing the barrier layer thickness and enhancing read operation speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the insulating layer is thickened to increase withstand voltage for writing, then the MTJ can withstand the applied voltage during write operations, but the resistance value of the MTJ becomes high and read time delay occurs
Solution Approach 1:
The patent divides the voltage application path into two separate paths: one for writing (through the insulating layer to the heavy metal layer) and one for reading (through the barrier layer of the MTJ). This segmentation allows the insulating layer to be optimized for voltage withstanding during writing without compromising the barrier layer thickness needed for fast reading.
Solution Approach 2:
The heavy metal layer acts as an intermediary that receives the write voltage through the insulating layer and generates spin current to reverse the recording layer's magnetization. This mediator approach allows voltage application without direct current flow through the MTJ, enabling the use of a thinner barrier layer for faster reading.
2Ease of operation
If a voltage is applied to the MTJ to lower magnetic anisotropy for easy magnetization reversal, then the recording layer can be reversed more easily, but a current flows to the MTJ during writing which increases resistance and slows down read operations
Solution Approach 1:
The patent extracts the voltage application function from the MTJ and relocates it to the heavy metal layer through the insulating layer. This extraction allows the MTJ to be optimized for reading (with a thin barrier layer) while the heavy metal layer handles the voltage application for writing operations.
Solution Approach 2:
The patent replaces the direct electrical current mechanism (current through MTJ) with a spin-orbit interaction mechanism (spin current from heavy metal layer). By applying voltage to the heavy metal layer, spin current is generated that acts on the recording layer's magnetization, eliminating the need for current flow through the MTJ.
3Speed
If the barrier layer is made thin to reduce MTJ resistance for fast reading, then the read operation speed increases, but the MTJ cannot withstand the high voltage required for writing operations
Solution Approach 1:
The patent segments the voltage withstanding function from the MTJ's barrier layer and assigns it to a separate insulating layer. This allows the barrier layer to be optimized for fast reading (thin structure) while the insulating layer provides the necessary voltage withstanding capability for writing operations.
Solution Approach 2:
The insulating layer serves as an intermediary between the voltage source and the heavy metal layer during writing operations. It provides the necessary dielectric strength to withstand the write voltage while preventing direct current flow to the MTJ, allowing the barrier layer to remain thin for fast reading.
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 faster read operations by reducing the resistance of the MTJ and eliminating current flow during writing, achieving high-speed data writing and reading while maintaining data integrity without external magnetic fields.
Implementation Method 1
a current is caused to flow to the heavy metal layer to induce a spin current by a spin-orbit interaction, and spins polarized by the spin current flow into the recording layer
Implementation Method 2
a magnetoresistance effect element, magnetic memory array, magnetic memory device, and write method for magnetoresistance effect element
Data Source
AI summary
The present invention provides a magnetoresistance effect element with a high read operation speed, a magnetic memory array, a magnetic memory device, and a write method for a magnetoresistance effect element. A magnetoresistance effect element includes: a heavy metal layer; a magnetic recording unit including a recording layer that includes a ferromagnetic layer that is magnetized in a vertical direction with respect to a film surface and is provided on a front surface of the heavy metal layer, a barrier layer that is provided on a surface of the recording layer which is opposite to the heavy metal layer and is formed from an insulator, and a reference layer which is provided on a surface of the barrier layer which is opposite to the recording layer, and a magnetization of the reference layer is fixed in the vertical direction with respect to a film surface; an insulating layer that is provided on a surface of the heavy metal layer which is opposite to the magnetic recording unit; a first terminal that is connected to the insulating layer at a position facing the recording layer with the heavy metal layer and the insulating layer interposed therebetween and applies a voltage to the heavy metal layer through the insulating layer; a second terminal that is connected to the reference layer; and a third terminal and a fourth terminal which are connected to the heavy metal layer, and cause a write current to flow to the heavy metal layer between the magnetic recording unit and the insulating layer.