Thin-Film Magnetic Head Read Gap Thickness Control
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Solution Overview
Problem
Thin-film magnetic heads with a CPP structure face challenges in maintaining precise read gap thickness and narrow free layer width due to variations in fabrication processes, leading to unstable read output and increased serial resistance, which hinders the achievement of high recording density and sensitivity.
Innovation Solution
A thin-film magnetic head design incorporating an additional metal layer with a nonmagnetic metal layer and a soft magnetic layer, where the soft magnetic layer serves as part of the upper magnetic shield, maintaining uniform thickness and allowing for a thinner cap layer, thereby stabilizing the read output and improving thickness accuracy of the read gap.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the read gap is narrowed to achieve high recording density, then recording density performance is improved, but thickness variation of the read gap increases and read output becomes unstable
Solution Approach 1:
An additional metal layer is introduced as an intermediary between the MR multi-layered structure and the upper electrode layer. This additional metal layer serves as a mediator that provides a uniform thickness reference, allowing precise control of the read gap thickness even when the read gap is narrowed for high recording density applications.
Solution Approach 2:
The invention changes the structural parameter by adding an extra metal layer with controlled thickness. This parameter change enables better control over the read gap thickness, reducing thickness variation and stabilizing read output while maintaining the ability to achieve high recording density through narrow read gap design.
2Productivity
If the read gap is narrowed to achieve high recording density, then recording density performance is improved, but magnetic coupling between magnetic shield layer and magnetic layers increases causing unstable read output
Solution Approach 1:
The additional metal layer acts as a nonmagnetic intermediary that separates the magnetic shield layer from the MR multi-layered structure. This intermediary layer prevents direct magnetic coupling between the magnetic shield layer and the magnetic layers (free layer and hard bias layer), thereby stabilizing read output while allowing the read gap to be narrowed for high recording density.
Solution Approach 2:
The invention extracts the magnetic coupling effect by introducing a nonmagnetic additional metal layer that physically separates magnetic components. This extraction removes the harmful magnetic interaction between the shield layer and magnetic layers, preventing read output instability while maintaining the narrow read gap structure needed for high recording density.
3Ease of manufacture
If conventional fabrication process is used, then manufacturing simplicity is maintained, but free layer width cannot be narrowed sufficiently for high recording density
Solution Approach 1:
The invention segments the metal structure into distinct functional layers: the MR multi-layered structure with the free layer, the additional metal layer, and the upper electrode layer. This segmentation allows independent optimization of each layer's thickness and function, enabling the free layer width to be narrowed for high recording density while maintaining fabrication simplicity through standard deposition and patterning processes.
Solution Approach 2:
The invention addresses the free layer width constraint by working in the thickness dimension through the additional metal layer. This dimensional approach allows the free layer width to be reduced without compromising manufacturing simplicity, as the additional metal layer provides structural support and magnetic shielding in the vertical dimension while enabling narrower horizontal dimensions for the free layer.
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 solution enhances the precision of read gap thickness and narrows the free layer width, stabilizing the read output even with a narrow read gap structure, improving the magnetic domain stability and frequency characteristics of the MR head.
Implementation Method 1
an upper magnetic shield layer laminated on the upper electrode layer. The additional metal layer has a multi-layered structure including a nonmagnetic metal layer and a soft magnetic layer laminated on the nonmagnetic metal layer
Implementation Method 2
a tunnel magnetoresistive effect (TMR) head with a TMR read head element having a current perpendicular to plane (CPP) structure
Data Source
AI summary
A thin-film magnetic head includes a lower magnetic shield layer, an MR multi-layered structure formed on the lower magnetic shield layer so that current flows in a direction perpendicular to surfaces of laminated layers, an insulation layer formed to surround the MR multi-layered structure, an additional metal layer laminated on at least the MR multi-layered structure, an upper electrode layer made of a soft magnetic material laminated on the additional metal layer and the insulation layer, and an upper magnetic shield layer laminated on the upper electrode layer. The additional metal layer has a multi-layered structure including a nonmagnetic metal layer and a soft magnetic layer laminated on the nonmagnetic metal layer, and has a length along a track-width direction of the MR multi-layered structure larger than a width of a magnetization-free layer in the MR effect multi-layered structure.