Magnetic Reader Crystal Decoupling Structure for Exchange Coupling
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Solution Overview
Problem
Conventional magnetic recording read transducers face issues with lower-than-desired exchange coupling between the AFM layer and the pinned layer, and suboptimal quality of the tunneling barrier layer, which affects the performance of the read sensor.
Innovation Solution
Incorporating a crystal decoupling structure with high crystalline temperature layers, such as Ta, Hf, W, or Ti, that remain amorphous up to elevated temperatures, allowing for improved crystallographic and magnetic properties of the read sensor layers during fabrication, including higher anneal temperatures without crystallization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the substrate is heated to elevated temperatures (e.g., 285°C) during AFM layer deposition, then the crystallographic and magnetic properties of the sensor layers are improved, but the CoFeB layer crystallizes which degrades the exchange coupling between the AFM layer and pinned layer
Solution Approach 1:
An amorphous magnetic layer (CoFeB) is introduced as an intermediary between the NiFe seed layer and the NiFe shield. This amorphous layer acts as a buffer that prevents crystal structure propagation from the shield to the sensor layers, while still allowing magnetic coupling to occur. The amorphous nature of this intermediate layer blocks the transmission of crystalline structure that would otherwise degrade the exchange coupling.
Solution Approach 2:
The patent changes the physical state parameter of the CoFeB layer from crystalline to amorphous. By depositing CoFeB in an amorphous state and maintaining it amorphous through the fabrication process (including elevated temperature deposition of AFM layer), the crystal structure propagation is prevented while magnetic properties are preserved or enhanced.
2Reliability
If conventional fabrication methods are used without a crystal decoupling structure, then the manufacturing process is simpler, but the tunneling barrier layer quality and sensor performance are degraded
Solution Approach 1:
The amorphous magnetic layer serves as a crystal decoupling structure that mediates between the crystalline shield and the sensor stack. This intermediate layer prevents crystal structure interference from the shield, enabling high-quality tunneling barrier layer deposition and improving overall sensor performance without requiring complex process 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
Enhances the exchange field and magnetoresistance of the read sensor, improving the overall performance of the magnetic read apparatus by decoupling the crystal structure of the shield from the seed and sensor layers, allowing for better magnetic coupling and sensor growth.
Implementation Method 1
a crystal decoupling structure with high crystalline temperature layers, such as Ta, Hf, W, or Ti, that remain amorphous up to elevated temperatures
Implementation Method 2
The substrate is heated, via step 18. The substrate is heated to nominally two hundred eighty-five degrees Celsius. Thus, the portion of the read transducer that has been fabricated is heated to approximately two hundred eighty five degrees Celsius.
Data Source
AI summary
A magnetic read apparatus has an air-bearing surface (ABS) and includes a shield, a crystal decoupling structure on the shield and a read sensor on the crystal decoupling structure. The crystal decoupling structure includes at least one of a magnetic high crystalline temperature amorphous alloy layer and a combination of a high crystalline temperature amorphous layer and an amorphous magnetic layer. The high crystalline temperature amorphous layer has a crystalline temperature of at least three hundred degrees Celsius. The amorphous magnetic layer is amorphous as-deposited.