Magnetoresistive Device with Compound Layer for Reliability
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Solution Overview
Problem
Current magnetoresistive devices face challenges in achieving high sensitivity and low thermal noise, particularly in CPP spin valve structures, where the microscopic metal conduction path is prone to electro-migration, leading to increased resistance and local heating, which compromises long-term reliability.
Innovation Solution
Incorporating a compound layer with electrovalent or covalently-bound characteristics between the metal conduction portion and the magnetization pinned or free films, and using an insulating film with a columnar metal conduction path to confine current and reduce parasitic resistance, while employing semiconductor materials to form ohmic junctions and suppress diffusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a microscopic metal conduction path is used in CPP spin valve to enhance magnetoresistive effect, then MR value increases, but resistance increases locally and heating occurs leading to reduced reliability
Solution Approach 1:
A compound layer is introduced as an intermediary between the metal conduction path and the magnetic layers. This compound layer acts as a thermal management interface that reduces local heating while maintaining electrical conduction, thereby resolving the contradiction between enhancing MR effect and preventing thermal damage
Solution Approach 2:
The patent uses composite material structure combining metal conduction path with compound layer (having electrovalent or covalent bonds). This composite structure provides both high electrical conductivity for MR effect and thermal management properties to prevent local heating, thus improving long-term reliability
2Reliability
If a microscopic metal conduction path is used in CPP spin valve to enhance magnetoresistive effect, then MR value increases, but resistance increases over time due to electro-migration
Solution Approach 1:
The compound layer serves as a protective intermediary between the metal conduction path and the surrounding environment, reducing electro-migration effects and stabilizing resistance over time while maintaining the enhanced MR effect
Solution Approach 2:
The patent changes the chemical and physical parameters of the conduction path by introducing a compound layer with specific bonding characteristics (electrovalent or covalent). This parameter change reduces electro-migration and stabilizes resistance, improving reliability
3Reliability
If device resistance is made large to reduce thermal noise, then S/N ratio improves, but frequency response property deteriorates
Solution Approach 1:
The patent optimizes the resistance parameter by introducing a compound layer that provides controlled electrical properties. This allows achieving optimal resistance value that balances thermal noise reduction (improving S/N ratio) and frequency response requirements
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 enhances the magnetoresistive effect, stabilizes the device's thermal properties, and improves long-term reliability by minimizing resistance increases and thermal diffusion, thereby achieving a better signal-to-noise ratio and extended product lifespan.
Implementation Method 1
the compound layer including a compound having at least one of an electrovalent-bound characteristic and a covalently-bound characteristic
Implementation Method 2
the compound layer including a compound having at least one of an electrovalent-bound characteristic and a covalently-bound characteristic
Implementation Method 3
suppress diffusion
Implementation Method 4
a columnar metal conduction portion formed within the insulating film to provide electrical conductivity
Implementation Method 5
a magnetoresistive device whose electric resistance changes in accordance with a magnetic field applied thereto
Implementation Method 6
magnetization is pinned by exchange bias or the like using the antiferromagnetic layer in advance
Data Source
AI summary
A magnetoresistive device includes a magnetoresistive film and a pair of electrodes for applying a sense current substantially perpendicularly to the magnetoresistive film. The magnetoresistive film includes a magnetization pinned film including a first ferromagnetic layer having a magnetization direction substantially pinned in one direction, a magnetization free film including a second ferromagnetic layer whose magnetization direction changes in accordance with an external magnetic field applied thereto, an intermediate layer formed between the magnetization pinned film and the magnetization free film and having an insulating film and a metal conduction portion extending in the film thickness direction of the insulating film, and a layer containing an electrovalent or covalent compound formed near the metal conduction portion.