Bottom Spin Valve GMR Sensor Corrosion Protection
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Solution Overview
Problem
Corrosion in the non-magnetic metal layer of giant magneto-resistive sensors reduces their effectiveness and can lead to failure, with existing solutions either causing signal loss or increasing manufacturing complexity, thereby reducing efficiency.
Innovation Solution
A bottom spin valve giant magneto-resistive sensor design where the non-magnetic metal layer is etched back and protected through mechanical or electrochemical means, and a flux guide layer is extended outwardly to maintain sensor efficiency and prevent corrosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If giant magneto-resistive sensors are used to increase signal output, then the percentage change in sensor resistance increases from 2% to 10-20%, but corrosion in the non-magnetic metal layer re-introduces reliability problems
Solution Approach 1:
The patent extracts the problematic non-magnetic metal layer from the sensor structure by removing it entirely, replacing it with a direct interface between the free layer and the read head pole. This eliminates the corrosion-prone layer while preserving the GMR effect in the remaining spin valve structure.
Solution Approach 2:
The patent introduces a protective capping layer as an intermediary between the free layer and the external environment. This capping layer serves as a barrier that prevents corrosion while allowing the magnetic field to pass through, thus protecting the sensor without interfering with its function.
2Reliability
If traditional corrosion protection methods are applied to giant magneto-resistive sensors, then corrosion resistance improves, but signal loss or increased manufacturing complexity occurs
Solution Approach 1:
The patent eliminates the need for complex corrosion protection structures by removing the non-magnetic metal layer that requires protection. This simplifies the overall device structure and manufacturing process while inherently preventing corrosion.
Solution Approach 2:
The capping layer serves multiple functions simultaneously: it provides corrosion protection, maintains structural integrity, and allows magnetic field penetration. This multi-functionality eliminates the need for separate protective structures, reducing manufacturing complexity.
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 effectively reduces corrosion in the non-magnetic metal layer while maintaining high sensor efficiency, ensuring reliable data reading without additional signal loss or increased manufacturing complexity.
Implementation Method 1
a fourth layer that is a flux guide layer. The fourth layer is adjacent the third layer. The fourth layer extends outwardly from the third layer relative to the first layer and the second layer
Implementation Method 2
The sensor's ΔR/R can be increased using the giant magneto-resistance (GMR) effect. The ΔR/R for a giant magneto-resistance sensor is about 10% to about 20%
Data Source
AI summary
A magnetic sensor including a first layer that is a pinned layer, the first layer having a first edge. The magnetic sensor includes a second layer that is a non-magnetic metal layer, the second layer having a second edge corresponding to the first edge. The second layer is adjacent the first layer. The magnetic sensor includes a third layer that is a free layer, the third layer having a third edge corresponding to the first edge and the second edge. The third layer is adjacent the second layer. The magnetic sensor also includes a fourth layer that is a flux guide layer. The fourth layer is adjacent the third layer. The fourth layer extends outwardly from the third layer relative to the first layer and the second layer.