PMR Writer Pole Sidewall Angle Control
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Solution Overview
Problem
Existing manufacturing processes for perpendicular magnetic recording (PMR) writer poles result in varying sidewall angles from the air-bearing surface (ABS) to the yoke region, leading to on-track reverse overwrite loss without mitigating skew impact on neighboring tracks.
Innovation Solution
A damascene process is employed to maintain an approximately constant sidewall angle of 2 degrees from the ABS to the yoke region by using a combination of etching and hard mask deposition techniques, ensuring similar etching rates for insulating and magnetic materials, and adjusting the sidewall angle in the yoke region to match the ABS region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a high sidewall angle is used for the writer pole at the air bearing surface, then skew impact on neighboring tracks is prevented, but on-track reverse overwrite loss increases
Solution Approach 1:
The patent applies local quality by creating different sidewall angles at different vertical positions of the writer pole. The ABS region maintains a high sidewall angle (e.g., 85-88 degrees) to prevent skew impact on neighboring tracks, while the yoke region has a lower sidewall angle (e.g., 70-75 degrees) to reduce on-track reverse overwrite loss. This spatial differentiation of geometric properties allows simultaneous optimization of both performance metrics.
2Ease of manufacture
If existing RIE processes are used, then manufacturing is simplified, but sidewall angle varies from ABS through yoke region due to RIE loading effect
Solution Approach 1:
The patent segments the etching process into two distinct stages with different parameters. The first etching process forms the ABS region with high sidewall angle using specific etch conditions, while the second etching process forms the yoke region with lower sidewall angle using modified etch conditions. This process segmentation allows independent optimization of each region's sidewall angle while using standard RIE equipment, maintaining ease of manufacture while achieving manufacturing precision.
Solution Approach 2:
The patent applies preliminary action by first forming the ABS region with the desired high sidewall angle before proceeding to form the yoke region. The etching process is carefully controlled to first establish the critical ABS geometry, then subsequently form the yoke region with adjusted parameters. This sequential approach ensures that the more critical ABS region is formed with optimal parameters first, while still achieving the desired varying sidewall angles throughout the structure.
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 improves on-track write field performance while minimizing skew impact on neighboring tracks by maintaining consistent sidewall angles, reducing on-track reverse overwrite loss.
Implementation Method 1
existing Alumina (Al2O3) based damascene reactive ion etching ('RIE') processes produce an inconsistent sidewall angle
Implementation Method 2
depositing (e.g., electroplating) a magnetic pole material into the trenches to form write poles
Data Source
AI summary
A process for manufacturing a writer main pole for a perpendicular magnetic recording system is provided. The writer pole may have a constant sidewall angle from the ABS to yoke and may be formed out of an insulating material and a magnetic material. The sidewall angle of the yoke region may be adjusted during manufacture. The ABS region may correspond to the magnetic material and the yoke region may correspond to the insulating material. The insulating material may comprise Alumina. The magnetic material may comprise a NiFe alloy.