TMR Junction Sidewall Bypass for Tunnel Barrier Reliability

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

The high density of reversal current in tunnel magnetoresistive effect (TMR) elements can lead to excessive current input into the magnetic tunnel junction, degrading the tunnel barrier layer and reducing the reliability of the TMR element.

Innovation Solution

A TMR element is designed with a side wall portion covering the magnetic tunnel junction, incorporating a minute particle region with dispersed insulation material and magnetic metal particles, which is electrically connected in parallel, allowing excessive current to bypass the junction and maintaining a constant current flow through the tunnel junction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If spin injection magnetization reversal (STT technology) is used to reverse the magnetization direction of the magnetization free layer, then the magnetization can be efficiently reversed from the viewpoint of electrical energy and no interconnect for magnetic field generation is necessary, but the density of the reversal current becomes high which degrades the tunnel barrier layer and decreases the reliability of the TMR element

Engineering Contradiction:

Improveelectrical energy efficiencyVSAvoidreliability of TMR element

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The invention segments the current path by introducing a separate bypass path through the side wall portion containing minute particle regions. The current is divided into two paths: one through the magnetic tunnel junction for magnetization reversal and another through the side wall portion to bypass excessive current, thereby protecting the tunnel barrier layer while maintaining STT efficiency

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The side wall portion with minute particle regions acts as an intermediary protective path. It provides an alternative route for excessive current, preventing direct damage to the tunnel barrier layer while allowing the necessary current to flow through the magnetic tunnel junction for magnetization reversal

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If a configuration is added to suppress excessive current input into the magnetic tunnel junction, then the reliability of the TMR element is improved, but the device complexity increases

Engineering Contradiction:

Improvereliability of TMR elementVSAvoidstructural complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The protective function is merged with the existing side wall structure. The side wall portion, which would normally just provide structural support and insulation, is enhanced by incorporating minute particle regions to provide current bypass functionality, combining structural and protective roles in one element

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The side wall portion is designed to serve multiple functions: providing structural support, electrical insulation, and current bypass protection. By making the side wall multi-functional, the need for separate protective components is eliminated, maintaining simplicity while improving reliability

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 effectively suppresses excessive current input into the magnetic tunnel junction, enhancing the reliability of the TMR element by maintaining a constant current value through the junction while allowing increased current flow through the minute particle region.

Implementation Method 1

In a current range where the applied current is 0 (ampere) to a certain current value, the electrical resistance value of the minute particle region is higher than that of the magnetic tunnel junction. Consequently, in a range where the applied current for the TMR element is 0 (ampere) to the current value, a current flows through the magnetic tunnel junction, and a current that flows through the minute particle region is maintained at almost 0 (ampere).

Methodology Applied

Scientific EffectElectrical Resistance: Electrical Resistance

Implementation Method 2

A technology called 'spin injection magnetization reversal' in which a spin transfer torque (STT) is applied to the magnetization free layer from electron spins by causing a spin-polarized current to flow through the magnetization free layer is known as a method of reversing the magnetization direction of the magnetization free layer of the TMR element

Methodology Applied

Scientific EffectSpin transfer torque:

Implementation Method 3

the TMR element that uses an insulation layer (tunnel barrier layer) as the non-magnetic spacer layer generally has high element resistance but can realize high magnetoresistance (MR ratio)

Methodology Applied

Scientific EffectTunnel magnetoresistive effect: Magnetoresistance

Data Source

PatentUS12120890B2Tunnel magnetoresistive effect element, magnetic memory, and built-in memory

Publication Date: 2024.10.15 TDK CORP

AI summary

A TMR element includes a magnetic tunnel junction, a side wall portion that covers a side surface of the magnetic tunnel junction, and a minute particle region that is disposed in the side wall portion. The side wall portion includes an insulation material. The minute particle region includes the insulation material and a plurality of minute magnetic metal particles that are dispersed in the insulation material. The minute particle region is electrically connected in parallel with the magnetic tunnel junction.