Closed-Flux Magnetoresistive Sensor Reference Layer Alignment

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Solution Overview

Problem

Magnetoresistive sensors face challenges in manufacturing due to time-consuming and costly local magnetization processes required for creating reference magnetizations, which hinder efficient production and increase costs while maintaining high sensor performance.

Innovation Solution

A magnetoresistive sensor design featuring a magnetic reference layer with a permanent closed flux magnetization pattern and a smaller magnetic free layer, where the centroid of the free layer is laterally displaced, allowing for the definition of reference magnetization direction without local magnetization processes, and a method to generate this pattern by applying an external magnetic field and reducing it to form closed flux patterns in the magnetic layer stack.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If local magnetization processes are used to create reference magnetizations, then accurate sensor performance is achieved, but manufacturing time increases and costs increase

Engineering Contradiction:

Improvesensor performanceVSAvoidmanufacturing efficiency

Core Design Contradiction:

Measurement precisionVSProductivity

Solution Approach 1:

The patent merges multiple local magnetization steps into a single global magnetization process. By designing the magnetic layer stack with a unified structure that responds to a single applied magnetic field, the reference magnetizations for multiple magnetoresistors are established simultaneously rather than individually, thereby improving manufacturing efficiency while maintaining sensor performance

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent incorporates preliminary design features in the magnetic layer stack structure (such as specific layer configurations and geometric arrangements) that enable the reference magnetizations to be self-aligned or easily aligned during a single magnetization step. This preliminary structural preparation eliminates the need for subsequent local adjustment processes

Inventive Principle:

Principle #10Preliminary action

2Measurement precision

If local magnetization processes are used to create reference magnetizations, then accurate sensor performance is achieved, but manufacturing costs increase

Engineering Contradiction:

Improvesensor performanceVSAvoidmanufacturing cost

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The magnetic layer stack structure is designed to self-align the reference magnetizations during a single global magnetization process. The specific layer configurations and geometric arrangements enable the magnetizations to automatically orient correctly without requiring complex local adjustment equipment or multiple processing steps, reducing manufacturing complexity and cost

Inventive Principle:

Principle #25Self-service

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 reduces manufacturing time and costs by avoiding local magnetization processes, enabling efficient production of magnetoresistive sensors with accurate and high-performance magnetization patterns.

Implementation Method 1

applying an external magnetic field in a predetermined direction to the magnetic layer stack causing magnetic saturation of the magnetic reference layer and of a pinned layer of the magnetic layer stack

Methodology Applied

Scientific EffectMagnetic saturation: Magnetic Saturation

Implementation Method 2

Magnetoresistive effects are based on numerous different physical phenomena. All of these phenomena have er in common that an electrical resistance of a resistive element is alterable by a magnetic field penetrating the resistive element

Methodology Applied

Scientific EffectMagnetoresistive effects: Magnetoresistance

Data Source

PatentUS11789097B2Magnetoresistive sensors and methods for generating closed flux magnetization patterns

Publication Date: 2023.10.17 INFINEON TECHNOLOGIES AG

AI summary

A method for generating a closed flux magnetization pattern of a predetermined rotational direction in a magnetic reference layer of a magnetic layer stack is provided. The method includes applying an external magnetic field in a predetermined direction to the magnetic layer stack causing magnetic saturation of the magnetic reference layer and of a pinned layer of the magnetic layer stack; and reducing the external magnetic field to form a first closed flux magnetization pattern in the magnetic reference layer and a second closed flux magnetization pattern in the pinned layer.