Magnetic Head Pole Layer Groove Etching for Track Width Precision
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Solution Overview
Problem
Magnetic heads for perpendicular magnetic recording systems face challenges in achieving high recording density and accurate track width definition due to issues like adjacent track erasing and degradation of recording characteristics, primarily caused by skew and difficulties in forming precise pole layers with inclined side surfaces.
Innovation Solution
A method for manufacturing a magnetic head with a pole layer that includes a track width defining portion and a wide portion, where the end face of the track width defining portion decreases in width towards the substrate, and a groove structure with specific etching steps to form the pole layer, allowing accurate track width definition and improved recording characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the track width is reduced to achieve higher recording density, then the linear recording density is improved, but the recording characteristics such as overwrite property suffer degradation
Solution Approach 1:
The pole layer is designed with different widths at different locations: a narrower track width defining portion at the medium facing surface for high recording density, and a wider wide portion at the substrate side for improved recording characteristics. This local variation in geometry allows simultaneous optimization of both recording density and overwrite property.
Solution Approach 2:
The solution transitions from considering only the track width (one dimension) to incorporating the vertical dimension by creating a pole layer with varying width through the thickness. The wide portion extends downward from the track width defining portion, utilizing the vertical dimension to improve magnetic flux distribution and recording characteristics without affecting the horizontal track width at the medium interface.
2Reliability
If the neck height is reduced to improve overwrite property, then the recording characteristics are improved, but the track width definition becomes less precise
Solution Approach 1:
The pole layer structure provides local quality optimization by concentrating the width variation effect at the wide portion while maintaining a well-defined track width at the medium facing surface. The neck height can be optimized for overwrite property without compromising track width definition because the track width is determined by the end face geometry at the medium interface, not by the neck height.
3Reliability
If the end face of the track width defining portion is formed with asymmetric shape to prevent skew, then adjacent track erasing is suppressed, but the manufacturing complexity increases
Solution Approach 1:
The end face of the track width defining portion is formed with an asymmetric shape where one end is longer than the other end in the track width direction. This asymmetry compensates for the skew effect during magnetic recording, preventing adjacent track erasing by adjusting the effective magnetic field distribution across the track.
Solution Approach 2:
The asymmetric end face geometry is built into the pole layer structure during manufacturing, preliminarily compensating for the skew effect that will occur during operation. This preliminary geometric adjustment eliminates the need for dynamic compensation mechanisms or complex control systems during recording.
4Manufacturing precision
If a groove structure with specific etching steps is used to form the pole layer, then the track width definition precision is improved, but the manufacturing process complexity increases
Solution Approach 1:
The groove formation process is segmented into multiple etching steps, each creating a specific portion of the final groove structure. This segmentation allows precise control over the groove geometry, including the width and depth variations needed to form the track width defining portion and wide portion with high precision.
Solution Approach 2:
The groove structure acts as an intermediary mold or template that guides the formation of the pole layer. By first creating the precise groove geometry and then filling it with pole layer material, the complex width variations are achieved through the groove template rather than direct pole layer patterning, simplifying the overall manufacturing approach.
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 enables the formation of a pole layer that prevents skew-related issues, allows for precise track width definition, and enhances recording characteristics such as overwrite property, thereby improving the overall performance of perpendicular magnetic recording systems.
Implementation Method 1
a coil that generates a magnetic field corresponding to data to be recorded on the recording medium; a pole layer that allows magnetic flux corresponding to the magnetic field generated by the coil to pass and that generates a recording magnetic field
Data Source
AI summary
A magnetic head includes: a pole layer including a track width defining portion and a wide portion; and an accommodation layer disposed on a bottom forming layer and having a groove that accommodates the pole layer. The groove includes a first portion for accommodating at least part of the track width defining portion, and a second portion for accommodating at least part of the wide portion. A manufacturing method for the magnetic head includes the steps of: forming a groove defining layer on a nonmagnetic layer that is intended to later become the accommodation layer; forming a mask that covers an area of the nonmagnetic layer where to form the first portion of the groove; etching the nonmagnetic layer so that the second portion of the groove is formed in the nonmagnetic layer; removing the mask; and taper-etching the nonmagnetic layer so that the first portion of the groove is formed in the nonmagnetic layer and the groove is thereby completed.