Bit Patterned Media Non-Magnetic Layer Trench Interference

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Solution Overview

Problem

Magnetic material in trenches between topographic features of hard disk drives causes unwanted magnetic flux, leading to readback interference and background noise, which existing methods like angled deposition do not fully address due to complex shapes and dimensional distortions.

Innovation Solution

A thicker non-magnetic layer is deposited on the topography before the magnetic layer, increasing the lateral diameter of land regions and reducing trench deposition, with deposition angles and material compositions optimized to minimize magnetic flux interference.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If magnetic material is blanket deposited on topographically patterned substrate, then magnetic recording layer is formed on pillars, but magnetic material accumulates in trenches causing unwanted magnetic flux and readback interference

Engineering Contradiction:

Improvemagnetic material in trenchesVSAvoidreadback interference

Core Design Contradiction:

Quantity of substanceVSObject-affected harmful factors

Solution Approach 1:

A non-magnetic intermediate layer is deposited between the topographic features and the magnetic recording layer. This intermediate layer acts as a mediator that prevents magnetic material from accumulating in the trenches while still allowing the magnetic layer to form properly on the pillars. The non-magnetic material fills the trenches and blocks magnetic flux generation, thereby reducing readback interference.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The harmful magnetic material is extracted or removed from the trenches by using the non-magnetic intermediate layer as a barrier. Instead of allowing magnetic material to deposit in the trenches during blanket deposition, the intermediate layer extracts this unwanted material accumulation, leaving only the desired magnetic recording on the pillars.

Inventive Principle:

Principle #2Taking out (Extraction)

2Quantity of substance

If angled deposition is used to reduce trench material, then some magnetic material in trenches is reduced, but significant deposits accumulate on sidewalls affecting magnetic properties

Engineering Contradiction:

Improvemagnetic material in trenchesVSAvoidsidewall deposits

Core Design Contradiction:

Quantity of substanceVSShape

Solution Approach 1:

The non-magnetic intermediate layer serves as a protective intermediary that prevents magnetic material from depositing on the sidewalls during angled deposition. By placing this intermediate layer first, the sidewalls are covered and protected, so when angled magnetic deposition occurs, the material deposits on the intermediate layer rather than directly on the pillar sidewalls, avoiding unwanted shape changes and magnetic property alterations.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Object-affected harmful factors

If non-magnetic layer is deposited to reduce trench deposition, then magnetic flux interference is reduced, but lateral diameter of land regions increases

Engineering Contradiction:

Improvemagnetic flux interferenceVSAvoidland region area

Core Design Contradiction:

Object-affected harmful factorsVSArea of moving object

Solution Approach 1:

The non-magnetic intermediate layer is deposited with locally varying thickness or coverage. In the trench regions, the layer is thicker and fully covers the harmful areas, effectively blocking magnetic flux. In the land region areas, the layer is thinner or optimized to minimize the increase in lateral diameter. This local quality variation allows the system to reduce magnetic flux interference while maintaining acceptable land region dimensions for recording.

Inventive Principle:

Principle #3Local quality

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

Significantly reduces magnetic flux and readback interference by minimizing magnetic material in trenches, maintaining magnetic properties and avoiding unwanted effects from non-magnetic sidewall deposition, achieving improved signal-to-noise ratios.

Implementation Method 1

An intermediate and significantly thicker non-magnetic layer is deposited on the topography prior to depositing the functional magnetic layer

Methodology Applied

Scientific EffectPhysical Vapour Deposition: Physical Vapour Deposition

Implementation Method 2

sputter deposition has only limited directionality

Methodology Applied

Scientific EffectSputter deposition: Sputtering

Data Source

PatentUS9058832B2Method of manufacturing a bit patterned media on a magnetic media disk

Publication Date: 2015.06.16 WESTERN DIGITAL TECHNOLOGIES INC

AI summary

A method of forming a bit patterned media on a magnetic media disk may include forming topographic features on a substrate and defining trenches therebetween. The method also may include forming non-magnetic material on the topographic features to define non-magnetic portions. In addition, magnetic material may be formed on the non-magnetic portions to define magnetic portions for a recording layer, such that the magnetic portions have a magnetic width that is greater than a non-magnetic width of the non-magnetic portions.