Read Transducer Soft Magnetic Bias Stability
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Solution Overview
Problem
Conventional magnetic recording read transducers experience reliability issues due to residual soft bias layer material left after fabrication, which is magnetically unstable and not fully stabilized by the shield, leading to potential instabilities in the transducer's performance.
Innovation Solution
The solution involves a magnetic transducer design where soft magnetic bias structures extend beyond the initial stripe height of the free layer, ensuring they are connected to the second shield, thereby increasing their stability and reducing residual material, which enhances the overall reliability of the transducer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the soft bias layer is deposited and partially milled through in step 16, then the stripe height of the free layer is set, but residue from the soft bias layer remains and is magnetically unstable
Solution Approach 1:
The patent extracts the problematic residue by extending the milling process through the soft bias layer completely, removing the unstable material that was previously left behind. This is achieved by adjusting the milling depth to go through the soft bias layer and into the underlying layers, thereby eliminating the source of magnetic instability.
Solution Approach 2:
The patent applies preliminary action by extending the pinned layer beyond the free layer stripe height before the milling process. This extended pinned layer structure allows the subsequent milling to remove the soft bias layer residue more effectively, as the extended pinned layer provides a structural framework that facilitates complete removal of the unstable residue material.
2Manufacturing precision
If the second conventional milling mask is used to set the pinned layer stripe height, then the pinned layer extends further from the ABS than the free layer, but the soft bias layer residue is prevented from being milled
Solution Approach 1:
The patent segments the milling process into distinct stages with different mask configurations. The first milling step sets the free layer stripe height, while the second milling step extends the pinned layer. By separating these operations and using appropriately configured masks for each, the process achieves both precise stripe height control and complete residue removal.
Solution Approach 2:
The patent introduces a dimensional change by extending the pinned layer in the vertical dimension (further from the ABS) beyond the free layer stripe height. This vertical extension provides an additional dimension for controlling the milling process, allowing the soft bias layer residue to be removed while maintaining precise horizontal stripe height control through the mask configuration.
3Ease of manufacture
If the soft bias structures extend only to the free layer stripe height, then the fabrication process is simpler, but the residue is not stabilized by the shield
Solution Approach 1:
The patent merges the soft bias structure extension with the shield structure, causing them to overlap in the vertical dimension. The extended soft bias structure is positioned to overlap with the shield, creating a combined magnetic structure where the shield provides stabilization to the previously unstable residue region. This merging eliminates the need for separate stabilization measures.
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 design improves the magnetic stability and reliability of the read transducer by ensuring a larger portion of the soft bias structures is connected to the shield, reducing residue and enhancing the transducer's performance.
Implementation Method 1
The soft magnetic bias structures 56 are used to magnetically bias the sensor layer of the sensor 54
Data Source
AI summary
A method and system provide a magnetic transducer having an air-bearing surface (ABS). The magnetic transducer includes a first shield, a read sensor, at least one soft magnetic bias structure and a second shield. The read sensor includes a sensor layer, a pinned layer and edge(s). The sensor layer has a first stripe height in a stripe height direction perpendicular to the ABS. The pinned layer has a second stripe height in the stripe height direction. The second stripe height is greater than the first stripe height. The soft magnetic bias structure(s) are adjacent to the edge(s) of the sensor. A portion of the soft magnetic bias structure(s) is further from the ABS than the first stripe height. The read sensor is between the first shield and the second shield. The soft magnetic bias structure(s) extend to the second shield.