Magnetic Read Head Pin Layer Stripe Height Definition
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Solution Overview
Problem
The scaling of read head dimensions in hard disk drives leads to edge degradation and thermal instability issues due to the short pinned layer stripe height, affecting magnetic head performance and reliability.
Innovation Solution
A magnetic sensor with a uniform hard or soft bias layer within the sensor stack, where the free layer stripe height is defined first, followed by the track width, and then the pinned layer stripe height, with the pinned layer and hard or soft bias layer defined in the same process step, eliminating partial bias layers and reducing instability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the pinned layer stripe height is reduced to scale read head dimensions, then higher areal density is achieved, but edge degradation and thermal instability occur
Solution Approach 1:
The pinned layer stripe height is defined first before defining the free layer stripe height and track width. This preliminary definition ensures that the pinned layer has sufficient height to maintain magnetic stability and prevent edge degradation, while still enabling the overall read head dimensions to be scaled down for higher areal density.
Solution Approach 2:
The invention applies different quality requirements to different parts of the sensor stack. The pinned layer is given a specific height requirement to ensure thermal stability and prevent edge degradation, while the free layer and other components are optimized for their specific functions. This local differentiation allows the system to achieve high areal density without compromising reliability.
2Reliability
If the pinned layer stripe height is extended to improve stability, then thermal stability improves, but read head dimensions increase
Solution Approach 1:
The pinned layer stripe height is predetermined and defined first in the manufacturing process, establishing a minimum height that ensures thermal stability. This preliminary definition allows subsequent layers to be configured optimally without compromising the pinned layer's stability, achieving a balance between reliability and compact dimensions.
Solution Approach 2:
The invention optimizes the pinned layer stripe height parameter to a specific value or range that provides sufficient thermal stability while maintaining compact overall dimensions. By carefully selecting and controlling this parameter, the system achieves thermal stability without excessive increase in read head dimensions.
3Ease of manufacture
If the pinned layer and bias layer are defined in separate process steps, then manufacturing flexibility is maintained, but partial bias layers are created causing instability
Solution Approach 1:
The definition of the pinned layer stripe height and the bias layer is merged into a single simultaneous process step. This combination ensures that both layers are defined with the same reference boundaries, eliminating the creation of partial bias layers and ensuring uniform bias field application across the entire pinned layer, thereby improving reliability without sacrificing manufacturing feasibility.
Solution Approach 2:
By defining the pinned layer and bias layer simultaneously in the same process step, the invention ensures homogeneous boundaries and uniform thickness across both layers. This homogeneity prevents the formation of partial bias layers and ensures consistent magnetic properties throughout the sensor stack, improving reliability.
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
This approach enhances the stability of the shape-enhanced pinned layer (SEP) structure, improving the magnetic head's performance and reliability by ensuring a uniform bias layer thickness, thereby reducing potential instability issues.
Implementation Method 1
A first hard or soft bias layer is formed within the first channel over the substrate, and the first hard or soft bias layer has a substantially uniform thickness within the first channel
Implementation Method 2
A typical GMR sensor includes a non-magnetic layer barrier such as MgO or spacer such as AgSn sandwiched between a pinned layer and a free layer
Implementation Method 3
A typical GMR sensor includes a non-magnetic layer barrier such as MgO or spacer such as AgSn sandwiched between a pinned layer and a free layer
Implementation Method 4
a typical TMR sensor includes a thin non-magnetic, electrically insulating barrier layer sandwiched between a pinned layer and a free layer
Implementation Method 5
The magnetization of the pinned layer is pinned by exchange coupling with an antiferromagnetic layer such as IrMn
Implementation Method 6
when the disk rotates, air is swirled by the rotating disk adjacent an air bearing surface (ABS) of the slider causing the slider to ride on an air a slight distance from the surface of the rotating disk
Data Source
AI summary
The present invention generally relates to a magnetic sensor in a read head having a hard or soft bias layer that is uniform in thickness within the sensor stack. The method of making such sensor is also disclosed. The free layer stripe height is first defined, followed by defining the track width, and lastly the pinned layer stripe height is defined. The pinned layer and the hard or soft bias layer are defined in the same process step. This approach eliminates a partial hard or soft bias layer and reduces potential instability issues.