TMR Element Insulating Layer Sidewall Protection
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Solution Overview
Problem
The magnetoresistance change ratio of TMR elements is reduced due to heat treatment, which can cause short-circuiting of the free and pinned layers through adhesion films or metal oxide layers formed during the manufacturing process of thin-film magnetic heads.
Innovation Solution
A magnetoresistance element with an insulating layer having an island-like structure section and a coating section, where the standard Gibbs energies of formation of the oxides satisfy specific relationships, preventing oxygen movement and subsequent reduction reactions that could short-circuit the layers during heat treatment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If heat treatment is performed during manufacturing, then the manufacturing process can be completed, but the magnetoresistance change ratio is reduced due to oxygen movement and reduction reactions
Solution Approach 1:
An insulating layer is introduced as an intermediary between the free layer and pinned layer to prevent direct interaction and short-circuiting. This insulating layer contains metal oxide particles that act as a barrier to oxygen movement during heat treatment, thereby maintaining the magnetoresistance change ratio while allowing the manufacturing process to proceed.
Solution Approach 2:
The standard Gibbs energy of formation of the metal oxide in the insulating layer is carefully selected to be higher than that of the adhesion film but lower than a threshold value. This parameter optimization ensures that during heat treatment, oxygen preferentially remains in the insulating layer rather than moving to the adhesion film, preventing reduction reactions that would short-circuit the magnetic layers.
2Ease of manufacture
If adhesion films are formed during etching, then the etching process is effective, but short-circuiting of free and pinned layers occurs through the adhesion films
Solution Approach 1:
The insulating layer serves as a mediator between the adhesion film and the magnetic layers (free layer and pinned layer). It prevents direct electrical contact through the adhesion film by providing an insulating barrier, thus avoiding short-circuiting while maintaining the effectiveness of the etching process that forms the adhesion film.
Solution Approach 2:
The insulating layer is formed as a composite material containing metal oxide particles dispersed in an insulating matrix. This composite structure provides both the adhesion properties needed for the etching process and the electrical insulation properties needed to prevent short-circuiting of the magnetic layers.
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 prevents a reduction in the magnetoresistance change ratio by suppressing oxygen movement and maintaining the integrity of the free and pinned layers, thereby enhancing the performance of the TMR element.
Implementation Method 1
A magnetoresistance element according to one aspect of the present invention uses the tunneling magnetoresistance effect
Implementation Method 2
the standard Gibbs energies of formation of metal oxides contained in a tunnel barrier layer, an island-like structure section and a coating section satisfy specific relationships with one another. By virtue of this, it is possible to prevent a reduction in a magnetoresistance change ratio of a magnetoresistance element caused by heat treatment
Data Source
AI summary
A TMR element includes a stack having a sidewall, and an insulating layer in contact with the sidewall. The stack includes a first ferromagnetic layer, a second ferromagnetic layer, and a tunnel barrier layer located between the first and second ferromagnetic layers. The insulating layer includes an island-like structure section in contact with only a part of the sidewall, and a coating section covering the island-like structure section and the sidewall. The tunnel barrier layer contains a first oxide. The island-like structure section contains a second oxide. Each of the first and second oxides is a metal oxide or semiconductor oxide. G2−G1 is 435 kJ/mol or smaller, where G1 and G2 are standard Gibbs energies of formation at 280° C. of the first oxide and the second oxide, respectively.