Magnetic Memory Device Diffusion Barrier

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Current magnetic memory devices face challenges in enhancing the tunnel magnetoresistance ratio (TMR) and anti-ferromagnetic coupling energy, particularly at higher annealing temperatures, due to diffusion of easily diffusing elements that degrade the performance of magnetic tunnel junction elements.

Innovation Solution

Incorporating a non-magnetic layer with a higher melting point, such as zirconium or hafnium, as a diffusion barrier between layers to prevent the diffusion of easily diffusing elements like platinum, which suppresses the degradation of spin polarizability and anti-ferromagnetic coupling, thereby maintaining improved TMR and coupling energy even at elevated temperatures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If annealing temperature is increased to improve TMR and anti-ferromagnetic coupling energy, then the tunnel magnetoresistance ratio and coupling energy are enhanced, but element diffusion occurs which degrades the performance of magnetic tunnel junction elements

Engineering Contradiction:

ImproveTMR and anti-ferromagnetic coupling energyVSAvoidelement diffusion

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

A non-magnetic layer with high melting point (zirconium oxide or hafnium oxide) is inserted between the ferromagnetic layer and the oxide layer. This intermediary layer acts as a diffusion barrier that prevents easy diffusion elements (such as platinum) from migrating into the oxide layer during high-temperature annealing, while still allowing the annealing process to proceed at temperatures sufficient to achieve the desired TMR and coupling energy enhancement.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent employs a composite structure combining multiple materials with different properties: ferromagnetic layers (CoFeB, CoFe), non-magnetic layers (Ru, Rh, Ir, Pt), and oxide layers (MgO, AlOx). The high-melting-point non-magnetic layer (ZrO2 or HfO2) is specifically selected for its dual functionality as both a structural component and a diffusion barrier, creating a composite material system that resists element diffusion while maintaining magnetic properties.

Inventive Principle:

Principle #40Composite materials

2Reliability

If high-temperature annealing is applied to enhance TMR, then the tunnel magnetoresistance ratio is improved, but spin polarizability degrades due to element diffusion

Engineering Contradiction:

ImproveTMRVSAvoidspin polarizability

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The high-melting-point non-magnetic layer serves as a protective intermediary that preserves spin polarizability by preventing element diffusion during the high-temperature annealing process required to achieve high TMR values.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the melting point parameter of the non-magnetic layer by selecting materials with significantly higher melting points (ZrO2: ~2700°C, HfO2: ~2500°C) compared to conventional materials. This parameter change enables the layer to withstand high-temperature annealing without undergoing phase transitions or excessive diffusion, thereby maintaining spin polarizability while achieving high TMR.

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 results in a magnetic tunnel junction element with enhanced TMR and anti-ferromagnetic coupling energy, maintaining performance at higher annealing temperatures compared to conventional designs without the diffusion barrier, leading to improved reliability and efficiency.

Implementation Method 1

Incorporating a non-magnetic layer with a higher melting point, such as zirconium or hafnium, as a diffusion barrier between layers to prevent the diffusion of easily diffusing elements like platinum

Methodology Applied

Scientific EffectDiffusion barrier: Diffusion Barrier

Implementation Method 2

A magnetic memory device (magnetoresistive random access memory, or MRAM) that incorporates a magnetoresistance effect element as a storage element

Methodology Applied

Scientific EffectMagnetoresistance effect: Magnetoresistance

Data Source

PatentUS11563168B2Magnetic memory device that suppresses diffusion of elements

Publication Date: 2023.01.24 KIOXIA CORP

AI summary

A magnetic memory device includes a magnetoresistance effect element including a first, second, and third ferromagnetic layer, a first non-magnetic layer between the first and second ferromagnetic layer, and a second non-magnetic layer between the second and third ferromagnetic layer. The second ferromagnetic layer is between the first and third ferromagnetic layer. The third ferromagnetic layer includes a fourth ferromagnetic layer in contact with the second non-magnetic layer, a third non-magnetic layer, and a fourth non-magnetic layer between the fourth ferromagnetic layer and the third non-magnetic layer. The first non-magnetic layer includes an oxide including magnesium (Mg). A melting point of the fourth non-magnetic layer is higher than the third non-magnetic layer.