Cap-Layer Interface for Magnetic Recording Media Adhesion

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Solution Overview

Problem

The existing carbon overcoat layer in heat-assisted magnetic recording media experiences decreased mechanical hardness and thermal stability during deposition, leading to poor adhesion and environmental degradation, resulting in smearing on the air bearing surface.

Innovation Solution

An additional interface layer, referred to as a cap-layer, is introduced between the magnetic recording layer and the carbon overcoat layer, optimized in thickness and material composition to enhance mechanical reliability and adhesion, while maintaining signal-to-noise ratio performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a carbon overcoat layer is deposited on the magnetic recording layer, then environmental protection is improved, but mechanical hardness decreases and thermal stability deteriorates

Engineering Contradiction:

Improveenvironmental protectionVSAvoidmechanical hardness

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The protective overcoat is segmented into multiple layers: a carbon-rich overcoat layer for environmental protection and an interface layer (cap-layer) with optimized composition for mechanical strength. This segmentation allows each layer to specialize in its function without compromising the other.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The interface layer uses a composite material composition (e.g., TiOx, SiOx, TaOx, MgOx) that combines the benefits of carbon-based environmental protection with oxide-based mechanical strength and thermal stability, creating a multi-functional protective structure.

Inventive Principle:

Principle #40Composite materials

2Reliability

If a carbon overcoat layer is deposited on the magnetic recording layer, then environmental protection is improved, but adhesion performance worsens

Engineering Contradiction:

Improveenvironmental protectionVSAvoidadhesion

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The interface layer acts as an intermediary between the magnetic recording layer and the carbon-rich overcoat layer, providing optimal adhesion properties that bridge the two materials and prevent delamination during writing and operation.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If the carbon overcoat layer is deposited, then environmental degradation is prevented, but smearing on the air bearing surface occurs

Engineering Contradiction:

Improveenvironmental protectionVSAvoidsmearing

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The overcoat structure implements local quality differentiation where the carbon-rich overcoat layer provides environmental protection while the interface layer controls surface properties to prevent smearing, with each layer having optimized composition for its specific function.

Inventive Principle:

Principle #3Local quality

4Reliability

If the carbon overcoat layer is deposited, then environmental protection is improved, but thermal stress increases during writing

Engineering Contradiction:

Improveenvironmental protectionVSAvoidthermal stress

Core Design Contradiction:

ReliabilityVSStress or pressure

Solution Approach 1:

The interface layer composition parameters (oxide content, thickness) are optimized to manage thermal stress during writing, creating a gradient structure that accommodates thermal expansion differences between the carbon overcoat and magnetic recording layer.

Inventive Principle:

Principle #35Parameter changes

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 cap-layer improves the mechanical performance of the carbon overcoat layer, preventing smearing and environmental degradation, and reduces thermal stress during writing, resulting in increased durability and power savings through optimized optical properties.

Implementation Method 1

sputter deposition is used to deposit the interface layer

Methodology Applied

Scientific EffectSputter deposition: Sputtering

Implementation Method 2

a refractive index of the interface layer is set at or between about 0.5 and about 1.6 based at least in part on a material composition used for the interface layer and a thickness of the interface layer, and wherein a refractive index of the carbon overcoat layer is set at or between about 2.0 and about 2.5 based at least in part a thickness of the carbon overcoat layer

Methodology Applied

Scientific EffectOptical absorption: Absorption (EM radiation)

Data Source

PatentUS11348613B2Adding a cap-layer to improve magnetic recording media

Publication Date: 2022.05.31 SEAGATE TECH LLC

AI summary

Systems and methods for adding a cap-layer to magnetic recording media are described. In one embodiment, the method may include depositing a magnetic recording layer over a substrate, depositing an interface layer over the magnetic recording layer, and depositing a carbon overcoat layer over the interface layer. In some cases, sputter deposition is used to deposit at least the interface layer. In some cases, oxygen is used as a background gas of the sputter deposition.