TMR Sensing Element With IrMn-TaN Stack for Thermal Stability
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Solution Overview
Problem
Magnetoresistive sensors, particularly tunnel magnetoresistance (TMR) sensors, face challenges with low thermal stability, which leads to degradation in back-end-of-line (BEOL) processes and reduced lifetime due to decreased sensitivity and increased angle error drift over time.
Innovation Solution
A TMR sensing element with a layer stack that includes a tantalum-nitride (TaN) layer and a natural antiferromagnetic (NAF) layer comprising iridium-manganese (IrMn), where the NAF layer is formed in direct contact with the TaN layer, increasing the blocking temperature and enhancing thermal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional TMR sensing element structure is used, then the device can be manufactured with standard processes, but the thermal stability is low leading to degradation in BEOL processes and reduced lifetime
Solution Approach 1:
The patent applies composite materials by combining IrMn (iridium-manganese) and TaN (tantalum-nitride) layers to form a natural antiferromagnetic structure. This composite structure increases the blocking temperature from conventional levels to above 260°C, providing enhanced thermal stability that prevents degradation during BEOL processes and extends device lifetime.
Solution Approach 2:
The patent changes the blocking temperature parameter of the antiferromagnetic layer by introducing direct contact between the IrMn layer and TaN layer. This parameter change from conventional blocking temperatures to above 260°C resolves the thermal stability issue while maintaining compatibility with standard manufacturing processes.
2Reliability
If the blocking temperature of the NAF layer is increased through direct contact with TaN layer, then thermal stability is improved, but the device structure becomes more complex
Solution Approach 1:
The TaN layer serves as an intermediary between the IrMn NAF layer and the pinned layer. This intermediary structure enables direct contact that increases blocking temperature to above 260°C, providing thermal stability without requiring complex additional layers or structures. The TaN mediator facilitates the thermal stability improvement while maintaining structural simplicity.
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 increased blocking temperature of the NAF layer results in a more stable reference system, reducing degradation in BEOL processes and extending the lifetime of the TMR sensing element by maintaining sensitivity and reducing angle error drift.
Implementation Method 1
a coupling interlayer arranged between the pinned layer and the reference layer; and a natural antiferromagnetic (NAF) layer comprising iridium-manganese (IrMn), wherein the NAF layer is configured to hold the fixed pinned magnetization in a first magnetic orientation and hold the fixed reference magnetization in a second magnetic orientation
Implementation Method 2
wherein the direct contact of the NAF layer with the TaN layer increases a blocking temperature of the NAF layer
Implementation Method 3
A TMR effect occurs in a magnetic tunnel junction (MTJ), wherein the magnetic tunnel junction occurs at a thin insulator that separates two ferromagnets from one another
Implementation Method 4
Magnetoresistance is a property of a material to change a value of the material's electrical resistance when an external magnetic field is applied to the material
Data Source
AI summary
A tunnel magnetoresistance (TMR) sensing element includes a layer stack having a tantalum-nitride (TaN) layer; a reference layer system; a magnetic free layer having a magnetically free magnetization; and a tunnel barrier layer arranged between the reference layer system and the magnetic free layer. The reference layer system includes a pinned layer having a fixed pinned magnetization; a reference layer having a having a fixed reference magnetization; a coupling interlayer arranged between the pinned layer and the reference layer; and a natural antiferromagnetic (NAF) layer comprising iridium-manganese (IrMn), wherein the NAF layer is formed in direct contact with the TaN layer, wherein the NAF layer is configured to hold the fixed pinned magnetization in a first magnetic orientation and hold the fixed reference magnetization in a second magnetic orientation, and wherein the direct contact of the NAF layer with the TaN layer increases a blocking temperature of the NAF layer.