Magnetoresistive Sensor Elements with Self-Pinned Layers

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Solution Overview

Problem

Magnetic sensors using GMR elements face challenges in achieving full 360° sensing capability due to differences in magnetoresistive element heights and sensitivity axes, leading to complex manufacturing processes and size constraints.

Innovation Solution

Magnetoresistive elements with self-pinned ferromagnetic pinned layers, where first and second ferromagnetic films are coupled through an antiparallel coupling layer in an antiferromagnetic manner, are formed directly on the same substrate with the same height, eliminating sensitivity differences and allowing closer placement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If magnetoresistive elements are stacked through insulating layers to achieve full 360° sensing capability, then sensitivity coverage is improved, but height differences appear causing sensitivity differences between sensitivity axes and complicating manufacturing

Engineering Contradiction:

Improvesensitivity coverageVSAvoidheight uniformity

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The patent merges multiple magnetoresistive elements with different sensitivity axes (X-axis and Y-axis elements) onto the same substrate plane, eliminating the need for stacking through insulating layers. This integration approach maintains height uniformity while achieving full 360° sensing capability through the combined output of elements with orthogonal sensitivity directions.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

Instead of stacking elements in the vertical dimension (creating height differences), the patent arranges elements with different sensitivity axes in the planar dimension on the same substrate. This dimensional reorganization allows multiple sensitivity directions to coexist at the same height, avoiding sensitivity differences caused by height variations.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Manufacturing precision

If magnetoresistive elements are disposed separately to avoid height difference influence on photoresist application, then photoresist application quality is improved, but element size reduction is constrained

Engineering Contradiction:

Improvephotoresist application qualityVSAvoidsensor size

Core Design Contradiction:

Manufacturing precisionVSVolume of moving object

Solution Approach 1:

The patent combines magnetoresistive elements with different sensitivity axes onto the same substrate plane, allowing them to be positioned close together without the need for separate stacking structures. This merging approach enables compact sensor design while maintaining uniform height for high-quality photoresist application.

Inventive Principle:

Principle #5Merging (Combining)

3Adaptability or versatility

If magnetoresistive elements are positioned at different heights to achieve different sensitivity axes, then sensing capability is improved, but wiring routing becomes difficult requiring additional contact hole processes

Engineering Contradiction:

Improvesensing capabilityVSAvoidmanufacturing process complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent merges elements with different sensitivity axes onto the same substrate plane, allowing all elements to be connected through planar wiring routes. This eliminates the need for vertical through-substrate connections and contact holes, significantly simplifying the manufacturing process while maintaining full sensing capability.

Inventive Principle:

Principle #5Merging (Combining)

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 enables the formation of magnetoresistive elements with different sensitivity axes on the same substrate without height differences, simplifying manufacturing and reducing sensor size by eliminating the need for additional clearances and complex wiring processes.

Implementation Method 1

a first ferromagnetic film and a second ferromagnetic film are coupled to each other through an antiparallel coupling layer in an antiferromagnetic manner

Methodology Applied

Scientific EffectAntiferromagnetic coupling: Magnetism

Implementation Method 2

a magnetic sensor using magnetoresistive elements (GMR elements) which utilize a giant magnetoresistive effect

Methodology Applied

Scientific EffectGiant magnetoresistive effect: Magnetoresistance

Data Source

PatentUS9207293B2Method for manufacturing a magnetic sensor

Publication Date: 2015.12.08 ALPS ALPINE CO LTD

AI summary

A magnetic sensor having no sensitivity differences between sensitivity axes, and an easy manufacturing method therefor are provided. The method includes a process of forming first stacked films for a magnetoresistive element on a substrate. This element has a sensitivity axis in a certain direction and includes a self-pinned ferromagnetic pinned layer in which first and second ferromagnetic films are antiferromagnetically coupled through an antiparallel coupling layer, a nonmagnetic intermediate layer, and a soft magnetic free layer. The method further includes a process of removing a region of the first stacked films from the substrate. The remaining region of the films includes at least a region to be left to form the element. The method furthermore includes a process of forming second stacked films for a magnetoresistive element, which has a sensitivity axis in a direction different from the certain direction and has the same structure, on the exposed substrate.