SOT MRAM Device with Spin-Orbit Torque Layer

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Current spin transfer torque random access memory (STT-RAM) technologies face challenges in achieving fast write speeds and low power consumption, which are essential for cache applications, due to inherent trade-offs in endurance and retention, and existing solutions like high frequency-assisted write operations are not feasible.

Innovation Solution

The integration of a spin-orbit torque (SOT) mechanism in MRAM assisted non-volatile memory Hall effect devices, utilizing a spin-orbit active layer and a combination of spin transfer and spin-orbit interactions to switch the magnetic moment of a free magnetic layer, enabling faster write operations with reduced current consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If spin transfer torque (STT) is used to write data in MRAM, then the magnetic moment can be switched, but the write speed is slow and power consumption is high

Engineering Contradiction:

Improvewrite speedVSAvoidpower consumption

Core Design Contradiction:

SpeedVSUse of energy by moving object

Solution Approach 1:

The patent introduces a spin-orbit active layer as an intermediary between the current source and the magnetic layer. Instead of directly passing current through the magnetic tunnel junction (STT method), the current flows through the spin-orbit active layer which generates spin-orbit torque to switch the magnetic moment. This intermediary approach enables faster switching with lower power consumption by leveraging the spin Hall effect or Rashba effect in the spin-orbit active layer.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If conventional STT-RAM is used, then non-volatile storage is achieved, but endurance and retention show inherent trade-offs

Engineering Contradiction:

Improveendurance and retentionVSAvoidwrite operation efficiency

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent changes the fundamental parameter of the writing mechanism from spin transfer torque to spin-orbit torque. This parameter change allows simultaneous improvement in endurance (by reducing write current stress on the MTJ), retention (by achieving more reliable magnetic switching), and write operation efficiency (by enabling faster switching speeds through the spin Hall effect or Rashba effect in the spin-orbit active layer).

Inventive Principle:

Principle #35Parameter changes

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 provides an order-of-magnitude improvement in write current and speed, making it suitable for high-speed, low-power cache applications by leveraging spin-orbit torque to rapidly deflect the magnetic moment, thus overcoming the limitations of conventional STT-RAM technologies.

Implementation Method 1

Methodology Applied

Scientific EffectSpin-orbit torque:

Implementation Method 2

An STT-RAM utilizes a magnetic tunneling junction (MTJ) written at least in part by a current driven through the MTJ. Another type of an MRAM is a spin orbit torque RAM (SOT-RAM).

Methodology Applied

Scientific EffectSpin transfer torque:

Data Source

PatentUS11195991B2Magnetic random access memory assisted devices and methods of making

Publication Date: 2021.12.07 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

A magnetic random access memory assisted non-volatile Hall effect device includes a spin orbit torque layer disposed over a substrate, and a magnetic layer disposed over the spin orbit torque layer. A metal oxide layer disposed over the magnetic layer. Portions of the spin orbit torque layer extend outward from the magnetic layer and the metal oxide layer on opposing sides of a first direction and opposing sides of a second direction in plan view, and the second direction is perpendicular to the first direction.