Side Write Shield Perpendicular Magnetic Recording Head
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Solution Overview
Problem
Perpendicular magnetic recording heads face significant lateral fringing issues, leading to unwanted side-writing and instability in high areal recording densities, which existing technologies have not adequately addressed.
Innovation Solution
A three-way shielded magnetic pole structure is formed using reactive ion etching and ion beam etching with a metal mask, creating side shields that also shape the pole tip, reducing side fringing and allowing for a larger pole while maintaining track resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a perpendicular magnetic recording head is used to achieve high areal recording densities, then recording density is improved, but lateral fringing increases causing side-writing
Solution Approach 1:
The shield structure is segmented into multiple components: a main pole, side shields positioned laterally adjacent to the main pole, and a trailing shield. This segmentation allows each component to independently manage specific aspects of the magnetic field, with side shields specifically targeting lateral fringing while the main pole maintains recording density.
Solution Approach 2:
Side shields act as intermediary elements positioned between the main pole and adjacent tracks. These shields intercept and redirect fringing magnetic fields before they can reach adjacent tracks, effectively mediating the interaction between the recording head and the recording medium to prevent side-writing.
2Object-generated harmful factors
If side shields are added to reduce lateral fringing, then side-writing is reduced, but device complexity increases
Solution Approach 1:
The side shields are integrated with the main pole structure to form a unified magnetic circuit. The trailing shield connects to the side shields, merging multiple shielding functions into a cohesive structure. This integration reduces the number of discrete components and simplifies manufacturing while maintaining effective side-writing prevention.
Solution Approach 2:
The side shields serve multiple functions: they reduce lateral fringing, define track boundaries, and work in conjunction with the trailing shield to manage return flux. This multi-functionality reduces the need for additional specialized components, thereby reducing overall device complexity.
3Strength
If a larger pole is formed to improve signal strength, then recording signal is improved, but track resolution decreases
Solution Approach 1:
The pole structure exhibits local quality variations: the main pole has a larger cross-sectional area to generate strong magnetic signals, while the pole tip that contacts the recording medium is precisely controlled in size to maintain track resolution. The side shields provide localized field confinement at the boundaries, allowing the pole body to be larger without compromising track definition.
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 effectively reduces side fringing, enabling higher areal recording densities up to 500 Gb/in2 and preventing side overwriting, while allowing for a larger pole structure without compromising track definition.
Implementation Method 1
A first object of this invention is to provide a method of forming a shielded pole structure for a perpendicular magnetic recording (PMR) head
Implementation Method 2
A first object of this invention is to provide a method of forming a shielded pole structure for a perpendicular magnetic recording (PMR) head
Implementation Method 3
This invention relates generally to magnetic recording heads, particularly to perpendicular recording heads that produce their recording magnetic fields perpendicularly to the recording medium
Implementation Method 4
By means of fringing magnetic fields that extend between two emerging pole pieces, longitudinal recording heads form small magnetic domains within the surface plane of the magnetic medium
Implementation Method 5
a soft magnetic underlayer (SUL) formed within the medium acts as a stabilizing influence on these perpendicular domain structures
Data Source
AI summary
A perpendicular magnetic recording (PMR) head is fabricated with a pole tip shielded laterally by a separated pair of side shields and shielded from above by an upper shield. The side shields are formed by a RIE process using specific gases applied to a shield layer through a masking layer formed of material that has a slower etch rate than the shield material. A masking layer of Ta, Ru/Ta, TaN or Ti, formed on a shield layer of NiFe and using RIE gases of CH3OH, CO or NH3 or their combinations, produces the desired result. The differential in etch rates maintains the opening dimension within the mask and allows the formation of a wedge-shaped trench within the shield layer that separates the layer into two shields. The pole tip is then plated within the trench and, being aligned by the trench, acquires the wedge-shaped cross-section of the trench. An upper shield is then formed above the side shields and pole.