Trapezoidal Magnetic Write Pole for Leakage Reduction
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Solution Overview
Problem
Magnetic recording heads with rectangular cross-sections suffer from side writing or erasure on adjacent tracks due to magnetic field concentrations at sharp corners, and existing technologies face limitations in achieving high aerial densities due to superparamagnetic instabilities.
Innovation Solution
A trapezoidal write pole with a narrow bottom width and a top width 1.25 to 3 times larger, an aspect ratio of 1:1 to 10:1, is formed using a hybrid thermal flow process involving thermal baking and shrinking of resist trenches, followed by electroplating a magnetic material, to reduce magnetic field leakage and enhance thermal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a rectangular write pole is used, then the fabrication process is simple, but magnetic field concentration at sharp corners causes side writing or erasure on adjacent tracks
Solution Approach 1:
The patent applies asymmetry by changing the write pole cross-section from a symmetric rectangular shape to an asymmetric trapezoidal shape with a narrow bottom width and a top width 1.25 to 3 times larger. This asymmetric geometry eliminates the sharp corners that cause magnetic field concentration and side writing, while maintaining ease of fabrication through standard electroplating processes.
Solution Approach 2:
The patent changes the geometric parameters of the write pole by defining specific width ratios (top width 1.25 to 3 times the bottom width) and aspect ratios (1:1 to 10:1). These parameter changes optimize the magnetic field distribution to reduce leakage while preserving fabrication simplicity through conventional manufacturing methods.
2Reliability
If longitudinal magnetic recording is used, then the current technology isๆ็, but superparamagnetic instabilities limit recording densities above 40 Gbit/in2
Solution Approach 1:
The patent changes the fundamental recording parameter by transitioning from longitudinal to perpendicular magnetic recording orientation. This parameter change enables recording densities well beyond 100 Gbit/in2 by storing magnetic bits vertically, overcoming the superparamagnetic stability limitations that constrain longitudinal recording at high densities.
3Manufacturing precision
If perpendicular magnetic recording is implemented, then recording density can exceed 100 Gbit/in2, but the structure complexity increases with main pole and flux return pole
Solution Approach 1:
The patent applies asymmetry in the pole structure design where the write pole has a trapezoidal cross-section with a narrow bottom and wider top, and the gap length is optimized to be 0.5 to 2.0 times the bottom width. This asymmetric configuration enhances magnetic field concentration for high-density recording while maintaining a relatively simple single-pole structure compared to traditional perpendicular recording heads.
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 trapezoidal shape reduces magnetic field leakage, allowing for higher aerial densities and improved thermal stability in magnetic recording, while being compatible with heat-assisted magnetic recording (HAMR) processes and standard industry fabrication methods.
Implementation Method 1
heating the structure for a first amount of time at a first temperature to form a predetermined slope in the first and second sidewalls of the trench
Implementation Method 2
heating the capped trench for a second amount of time at a second temperature to shrink the separation of the first and second sidewalls of the trench
Implementation Method 3
electroplating a magnetic material in the trench
Implementation Method 4
A coil having a plurality of turns is located adjacent to the main write pole for inducing a magnetic field between the pole and a soft underlayer of the storage media
Implementation Method 5
removing the seed material outside the pole area by ion-beam etching to form the magnetic pole
Data Source
AI summary
A method for forming a magnetic write pole with a trapezoidal cross-section is described. The method consists of first forming a magnetic seedlayer on a base followed by depositing a removable material layer on the seedlayer, and then a resist layer on the removable material layer. A trench is then formed in the resist, and the resist is heated to cause the cross -sectional profile of the trench to assume a trapezoidal shape. The resist is then capped with another resist layer and further heated to cause the width of the trapezoidal trench to become narrower. The cap layer and removable material layer at the bottom of the trench are then removed and the trench filled with magnetic material by electroplating. The resist and seedlayer external to the trench are finally removed to form a write pole with a trapezoidal cross-section.