MTJ Layer Structure for Magnetic Anisotropy and Data Retention

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Solution Overview

Problem

Existing magnetoresistance memory devices face challenges in achieving high magnetic properties in memory cells, which affects data retention and storage efficiency.

Innovation Solution

The magnetoresistance memory device incorporates a specific layered structure including a first and second ferromagnetic layer, a metal layer for antiferromagnetic coupling, and ferromagnetic oxide layers with common elements to enhance magnetic anisotropy and retention properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional magnetoresistance memory devices are used, then device simplicity is maintained, but magnetic properties and data retention are insufficient

Engineering Contradiction:

Improvedata retentionVSAvoidlayered structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The memory device is segmented into multiple functional layers including first and second ferromagnetic layers, ferromagnetic oxide layers, metal layers, and insulating layers. Each layer performs a specific function contributing to overall magnetic properties and data retention, resolving the contradiction by dividing the device into specialized segments rather than using a simple uniform structure

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The device employs composite material structures where ferromagnetic layers are combined with ferromagnetic oxide layers containing common elements. This composite approach enhances magnetic anisotropy and retention properties by leveraging the complementary characteristics of different materials, achieving high reliability while managing complexity through material composition rather than structural complexity

Inventive Principle:

Principle #40Composite materials

2Strength

If ferromagnetic layers are added to improve magnetic properties, then magnetic anisotropy increases, but device structure becomes more complex

Engineering Contradiction:

Improvemagnetic anisotropyVSAvoidnumber of layers

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

Ferromagnetic oxide layers are strategically positioned between ferromagnetic layers to provide localized enhancement of magnetic anisotropy. The oxide layers contain common elements with the adjacent ferromagnetic layers, creating localized regions of high magnetic property without requiring the entire device structure to be complex

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

Ferromagnetic oxide layers serve as intermediary structures between metal layers and ferromagnetic layers. These intermediary layers facilitate antiferromagnetic coupling while enhancing magnetic anisotropy, allowing the device to achieve high magnetic strength without directly increasing the complexity of the primary ferromagnetic structure

Inventive Principle:

Principle #24Intermediary (Mediator)

3Duration of action of stationary object

If multiple ferromagnetic oxide layers are used to enhance retention, then data retention improves, but manufacturing complexity increases

Engineering Contradiction:

Improvedata retention durationVSAvoidlayer deposition complexity

Core Design Contradiction:

Duration of action of stationary objectVSEase of manufacture

Solution Approach 1:

The ferromagnetic oxide layers are designed with specific thickness parameters and compositional ratios of common elements to optimize retention properties. By controlling these parameters within specific ranges, the device achieves enhanced data retention duration while maintaining manufacturability through parameter optimization rather than structural complexity

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 configuration results in an MTJ element with improved magnetic properties, enhanced data retention, and increased resistance ratio, addressing the limitations of existing devices.

Implementation Method 1

The metal layer antiferromagnetically couples the first ferromagnetic layer and the first ferromagnetic oxide layer

Methodology Applied

Scientific EffectAntiferromagnetic coupling: Magnetism

Implementation Method 2

A magnetoresistance memory device stores data using an element exhibiting a magnetoresistance effect

Methodology Applied

Scientific EffectMagnetoresistance effect: Magnetoresistance

Implementation Method 3

The second ferromagnetic layer includes the one of iron and cobalt that is included in the first ferromagnetic oxide layer and one element of a first element group, and has an easy magnetization axis extending in a direction across an interface with the metal layer

Methodology Applied

Scientific EffectMagnetic anisotropy: Anisotropy

Data Source

PatentUS12329038B2Magnetoresistance memory device

Publication Date: 2025.06.10 KIOXIA CORP

AI summary

A magnetoresistance memory device includes first, second, third and fourth ferromagnetic layers; a first and second ferromagnetic oxide layers; a metal layer; an insulating layer. The second ferromagnetic layer includes one of iron and cobalt included in the first ferromagnetic oxide layer and one element of a first element group. The second ferromagnetic oxide layer includes an oxide of an alloy of the one of iron and cobalt included in the second ferromagnetic oxide layer with a first element, which has a standard electrode potential lower than that of iron or cobalt and that of the one element of the first element group included in the second ferromagnetic layer.