Magnetic Transducer Pinning Method for Signal-to-Noise Ratio
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Solution Overview
Problem
Conventional magnetoresistive (MR) sensors suffer from a degraded signal-to-noise ratio (SNR) due to canting of the synthetic antiferromagnetic (SAF) layers caused by hard bias structures during fabrication, which is exacerbated by high-temperature processing.
Innovation Solution
A method involving the initialization of hard bias magnetization with a first component aligned with the free layer direction and a second component aligned with the pinned layer direction, followed by thermal treatments above room temperature to reset the hard bias magnetization, thereby reducing canting and improving SNR.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If hard bias structures are provided with magnetization initialized along the free layer direction, then the pinned layer magnetization alignment is improved, but high-temperature processing causes canting and degrades signal-to-noise ratio
Solution Approach 1:
The patent applies preliminary action by initializing the hard bias magnetization with a specific configuration (first component along free layer direction, second component along pinned layer direction) before the detrimental high-temperature processing occurs. This preliminary magnetization state creates a protective effect that prevents canting during subsequent thermal processing, thereby maintaining pinned layer alignment and preserving signal-to-noise ratio.
Solution Approach 2:
The patent utilizes parameter changes by modifying the hard bias magnetization parameters - specifically setting up a dual-component magnetization state (with components along both free layer and pinned layer directions) that differs from conventional single-direction initialization. This parameter modification enables the system to withstand high-temperature processing without degrading the pinned layer alignment.
2Ease of manufacture
If conventional hard bias initialization is used, then fabrication is simpler, but thermal processing causes magnetization canting and increases noise
Solution Approach 1:
The patent implements preliminary action by establishing a specific hard bias magnetization configuration before thermal processing. The magnetization is initialized with components along both the free layer direction and pinned layer direction, creating a pre-conditioned state that protects against thermal damage during subsequent fabrication steps.
Solution Approach 2:
The patent applies preliminary anti-action by setting up the hard bias magnetization in a way that counteracts the detrimental effects of thermal processing. The dual-component magnetization configuration creates an opposing influence that prevents canting and maintains alignment stability during high-temperature steps.
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 method reduces the distribution of magnetization in the pinned layer, aligns ferromagnetic layers closer to the desired direction, and minimizes the impact of high-temperature processing, resulting in an improved signal-to-noise ratio for the magnetic transducer.
Implementation Method 1
performing at least one thermal treatment after the step of initializing the hard bias magnetization. The thermal treatment(s) are above room temperature.
Implementation Method 2
The hard bias magnetization is initialized such that a first component of the hard bias magnetization is along the first direction, while a second, nonzero component of the hard bias magnetization is along the second direction.
Data Source
AI summary
A method comprises providing a magnetic element including a free layer, a pinned layer, a nonmagnetic spacer layer between the free and pinned layers, and a pinning layer adjacent the pinned layer. The free layer is biased in a first direction. The pinned layer has a first layer having a first magnetization, a second layer having a second magnetization, and a nonmagnetic layer between the first and second layer. The first magnetization is pinned parallel to a second direction substantially perpendicular to the first direction and substantially perpendicular to the ABS. The second magnetization is antiparallel to the second direction. The pinning layer is oriented along the second direction. The method further comprises providing a hard bias structure having a hard bias magnetization, initializing the hard bias magnetization along the second direction, performing at least one thermal treatment, and resetting the hard bias magnetization substantially along the first direction.