Magnetic Memory Device Wiring Structure for Internal Bias

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Solution Overview

Problem

Current magnetic memory devices face challenges in efficiently writing data using the spin orbit torque method without adding complexity to the device structure, particularly in generating the necessary magnetic field bias for magnetoresistance effect elements with perpendicular magnetization.

Innovation Solution

The proposed magnetic memory device incorporates a wiring structure with a ferromagnetic layer and a non-magnetic layer, comprising ruthenium, iridium, or osmium, which generates a spin orbit torque and applies a bias magnetic field internally, allowing for data writing without an external magnetic field, thereby simplifying the write operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If an external magnetic field is applied to write data in magnetoresistance effect elements with perpendicular magnetization, then data writing capability is achieved, but device complexity and operational load increase

Engineering Contradiction:

Improvedata writing operationVSAvoidmagnetic field generation structure

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The patent combines the write current path and magnetic field bias generation into a single integrated wiring structure. The wiring includes a ferromagnetic layer and a non-magnetic layer (containing ruthenium, iridium, or osmium) that work together to generate both the spin orbit torque and the magnetic field bias simultaneously, eliminating the need for separate external magnetic field generation components.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The wiring structure serves dual functions: it carries the write current to generate spin orbit torque while simultaneously generating the magnetic field bias through its own composition. The ferromagnetic layer and non-magnetic layer work together to provide the necessary magnetic field bias internally, allowing the device to write data without requiring external magnetic field generation infrastructure.

Inventive Principle:

Principle #25Self-service

2Reliability

If a wiring structure with ferromagnetic layer and non-magnetic layer is added to generate spin orbit torque, then internal magnetic field bias is achieved, but device structure becomes more complex

Engineering Contradiction:

Improvemagnetic field bias generationVSAvoidwiring structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The wiring structure is designed to perform multiple functions simultaneously: it serves as the current path for write operations, generates spin orbit torque through its material composition, and provides magnetic field bias for perpendicular magnetization switching. This multi-functionality reduces the need for separate components while achieving reliable internal magnetic field bias generation.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The wiring structure uses a composite of ferromagnetic layer and non-magnetic layer (with ruthenium, iridium, or osmium) to achieve properties that neither material could provide alone. The ferromagnetic layer provides magnetic field generation capability while the non-magnetic layer with high spin-orbit coupling enhances spin orbit torque, creating a synergistic effect that enables reliable internal magnetic field bias.

Inventive Principle:

Principle #40Composite materials

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 reduces the load of the write operation by generating the required magnetic field bias internally, enhancing data writing efficiency while maintaining device complexity at a manageable level.

Implementation Method 1

The non-magnetic layer has a film thickness of 3 nanometers or less, and comprises an element selected from ruthenium, iridium, rhodium, and osmium. The non-magnetic layer generates a spin orbit torque.

Methodology Applied

Scientific EffectSpin orbit torque:

Implementation Method 2

The wiring includes a ferromagnetic layer and a non-magnetic layer... applies a bias magnetic field internally

Methodology Applied

Scientific EffectMagnetic field bias: Magnetic Field

Data Source

PatentUS20230082665A1Magnetic memory device

Publication Date: 2023.03.16 KIOXIA CORP

AI summary

A magnetic memory device includes a three-terminal type memory cell. A first terminal is connected to a first conductor layer. A second terminal is connected to a second conductor layer. A third terminal is connected to a third conductor layer. The memory cell includes a fourth conductor connected to the first conductor layer, the second conductor layer, and the third conductor layer. A magnetoresistance effect element of the memory cell is coupled between the third conductor layer and the fourth conductor layer. A first switching element is coupled to the second conductor layer and the fourth conductor layer. A second switching element coupled to the first conductor layer and the third conductor layer. The fourth conductor layer includes a first ferromagnetic layer and a first non-magnetic layer. The first non-magnetic layer comprises at least one of ruthenium, iridium, rhodium, or osmium.