Magnetic Domain Wall Element Impurity Adhesion

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Solution Overview

Problem

Miniaturization of magnetoresistance effect elements leads to impurity adhesion on side walls, causing deterioration in magnetic characteristics and reliability due to ion beam irradiation, resulting in leakage and reduced reliability.

Innovation Solution

A magnetic domain wall movement element with a specific lamination structure including a first ferromagnetic layer, a nonmagnetic layer, and a second ferromagnetic layer, where the first ferromagnetic layer's side surface is inclined and the nonmagnetic layer's thickness is 30 Å or larger, with controlled milling rates and underlayer configurations to prevent impurity adhesion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of moving object

If ion beam irradiation is performed to slim the magnetoresistance effect element, then the area of the element is reduced, but impurities scatter and adhere to the side wall causing deterioration in magnetic characteristics and reliability

Engineering Contradiction:

Improvearea of magnetoresistance effect elementVSAvoidreliability of magnetoresistance effect element

Core Design Contradiction:

Area of moving objectVSReliability

Solution Approach 1:

A nonmagnetic layer with high milling rate is introduced as an intermediary between the ferromagnetic layer and the ion beam irradiation process. This nonmagnetic layer acts as a protective mediator that prevents direct interaction between scattered metal impurities and the ferromagnetic side wall, thereby preventing impurity adhesion and maintaining magnetic characteristics while enabling area reduction through slimming

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention changes the material composition parameter by introducing a nonmagnetic layer with specific properties (high milling rate, thickness of 1-10 nm). This parameter change allows the structure to withstand ion beam irradiation without suffering from impurity adhesion, resolving the contradiction between area reduction and reliability maintenance

Inventive Principle:

Principle #35Parameter changes

2Area of moving object

If ion beam irradiation is performed to slim the magnetoresistance effect element, then the area of the element is reduced, but adhered impurities cause leakage

Engineering Contradiction:

Improvearea of magnetoresistance effect elementVSAvoidleakage current

Core Design Contradiction:

Area of moving objectVSObject-generated harmful factors

Solution Approach 1:

The nonmagnetic layer serves as a protective intermediary that prevents scattered metal impurities from adhering to the ferromagnetic side wall. By blocking the direct path for impurity adhesion, this layer prevents the formation of leakage paths, thereby eliminating the harmful effect of leakage current while enabling area reduction

Inventive Principle:

Principle #24Intermediary (Mediator)

3Area of moving object

If ion beam irradiation is performed to slim the magnetoresistance effect element, then the area of the element is reduced, but magnetic characteristics deteriorate

Engineering Contradiction:

Improvearea of magnetoresistance effect elementVSAvoidmagnetic characteristics

Core Design Contradiction:

Area of moving objectVSManufacturing precision

Solution Approach 1:

The nonmagnetic layer with high milling rate acts as a protective intermediary during ion beam irradiation. It prevents direct damage to the ferromagnetic layer's side wall by blocking scattered impurities, thereby preserving magnetic characteristics such as coercivity and saturation magnetization while still enabling the slimming process to reduce area

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

By changing the material parameter to include a nonmagnetic layer with specific properties (high milling rate, controlled thickness), the invention protects magnetic characteristics from deterioration during the slimming process, allowing area reduction without sacrificing manufacturing precision of magnetic properties

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

The solution enhances the reliability of magnetoresistance effect elements by preventing impurity adhesion during slimming, maintaining magnetic characteristics and ensuring reliable operation.

Implementation Method 1

a nonmagnetic layer provided on the first ferromagnetic layer... preventing impurity adhesion

Methodology Applied

Scientific EffectPhysical barrier protection:

Implementation Method 2

a side surface of the first ferromagnetic layer inclined with respect to the lamination direction

Methodology Applied

Scientific EffectGeometric configuration:

Data Source

PatentUS11963461B2Magnetic domain wall movement element and magnetic recording array

Publication Date: 2024.04.16 TDK CORP

AI summary

A magnetic domain wall movement element according to the present embodiment includes a first ferromagnetic layer, a nonmagnetic layer, and a second ferromagnetic layer that are laminated in an order from a side close to a substrate. On a cross-section along a lamination direction and a second direction orthogonal to a first direction in which the first ferromagnetic layer extends in a plan view from the lamination direction, a shortest width of the first ferromagnetic layer in the second direction is shorter than a width of the nonmagnetic layer in the second direction.