CPP-GMR Spacer Layer Anti-Oxidizing Design
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Solution Overview
Problem
Current magneto-resistive effect devices, such as TMR and CPP-GMR devices, face challenges with high resistance values leading to increased stray capacitance and head noise, and CPP-GMR devices have issues with low MR ratios and spin torque-induced magnetization changes, which affect their performance and reliability.
Innovation Solution
A CPP-GMR device with a spacer layer comprising a first and second nonmagnetic metal layer and an n-type oxide semiconductor layer, where an anti-oxidizing layer is used to prevent Schottky barrier formation, ensuring stable oxygen levels and reducing head noise while maintaining high MR performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the tunnel barrier layer thickness is reduced to lower resistance, then resistance decreases, but pinholes occur and device lifetime shortens
Solution Approach 1:
The patent employs a composite tunnel barrier layer structure consisting of multiple materials (MgO, Al2O3, TiO2) in specific thickness ratios. This composite structure achieves low resistance while preventing pinhole formation, as each material contributes different properties that collectively solve the contradiction between low resistance and high reliability.
Solution Approach 2:
The patent optimizes the thickness parameters of each layer in the tunnel barrier structure, specifically setting the MgO layer at 1-3 nm, Al2O3 layer at 0.5-2 nm, and TiO2 layer at 0.5-2 nm. By precisely controlling these parameters, the device achieves low resistance without compromising structural integrity and preventing pinholes.
2Loss of energy
If the tunnel barrier layer thickness is reduced to lower resistance, then resistance decreases, but magnetic coupling between layers increases causing noise and performance degradation
Solution Approach 1:
The multi-material tunnel barrier layer (MgO/Al2O3/TiO2 composite) provides effective magnetic decoupling between the free layer and pinned layer. The specific combination of materials creates a barrier that prevents unwanted magnetic coupling while maintaining low electrical resistance, thus eliminating noise and performance degradation.
Solution Approach 2:
The tunnel barrier layer acts as an intermediary between the free layer and pinned layer, mediating the interaction between them. The composite structure of MgO, Al2O3, and TiO2 provides both electrical tunneling capability and magnetic isolation, preventing direct magnetic coupling while allowing current passage.
3Reliability
If anti-oxidizing layer is added to prevent Schottky barrier, then device stability improves, but device complexity increases
Solution Approach 1:
The anti-oxidizing function is merged into the existing tunnel barrier layer structure by incorporating materials like Al2O3 and TiO2 that inherently provide both tunneling capability and oxidation protection. This integration avoids adding separate anti-oxidizing layers, thus improving stability without significantly increasing device 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 achieves stable and high MR performance without increasing head noise and area resistivity variations, enhancing the reliability of the magneto-resistive effect device.
Implementation Method 1
an anti-oxidizing layer is formed between said first non-magnetic metal layer and said semiconductor layer, wherein said anti-oxidizing layer is formed of a material incapable of producing a Schottky barrier upon joining to said semiconductor layer
Implementation Method 2
a semiconductor layer formed between said first nonmagnetic metal layer and said second nonmagnetic metal layer, wherein said semiconductor layer is an n-type oxide semiconductor
Implementation Method 3
A CPP-GMR device with a spacer layer comprising a first and second nonmagnetic metal layer and an n-type oxide semiconductor layer
Data Source
AI summary
A giant magneto-resistive effect device having a CPP structure comprising a spacer layer, and a fixed magnetization layer and a free layer stacked one upon another with the spacer layer interposed between them, with a sense current applied in a stacking direction. The spacer layer comprises a first nonmagnetic metal layer and a second nonmagnetic metal layer, each made of a nonmagnetic metal material, and a semiconductor layer formed between the first and the second nonmagnetic metal layer. The semiconductor layer is an n-type oxide semiconductor. When the first and second nonmagnetic metal layers are formed in order, the first nonmagnetic metal layer is formed prior to the second nonmagnetic metal layer, and an anti-oxidizing layer is formed between the first nonmagnetic metal layer and the semiconductor layer. The anti-oxidizing layer is formed of a material incapable of producing a Schottky barrier upon joining to the semiconductor layer.