CoPtBN Capping Layer for HAMR Areal Density and Grain Protection

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Solution Overview

Problem

Existing magnetic recording media face challenges in achieving high areal density capabilities due to limitations in capping layer design, which affect the readback signal and grain boundary integrity in heat-assisted magnetic recording systems.

Innovation Solution

A CoPtBN capping layer with a face-centered cubic (FCC) crystalline structure and 5-12 atomic percentage of Pt is introduced, enhancing vertical exchange coupling and reducing etch damage to FePt grains, thereby improving readback signal and areal density.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a conventional capping layer is used, then the structure is simple, but the areal density capability is limited and etch damage occurs

Engineering Contradiction:

Improveareal density capabilityVSAvoidcapping layer composition

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent changes the compositional parameters of the capping layer by incorporating Pt into Co-BN at specific atomic percentages (5-12 at.% Pt). This parameter modification improves areal density capability by enhancing vertical exchange coupling and reducing etch damage to FePt grains, while maintaining the overall layered structure simplicity

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite capping layer material (CoPtBN) by combining multiple elements (Co, Pt, B, N) with specific atomic ratios. This composite material provides superior performance in terms of etch resistance and exchange coupling compared to conventional single-material capping layers, directly addressing the areal density limitation

Inventive Principle:

Principle #40Composite materials

2Measurement precision

If Pt content is increased to improve readback signal, then readback signal improves, but etch damage to FePt grains increases

Engineering Contradiction:

Improvereadback signalVSAvoidetch damage to FePt grains

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent identifies and optimizes the Pt atomic percentage parameter to a specific range (5-12 at.%). Within this range, the readback signal is enhanced through improved vertical exchange coupling, while etch damage to FePt grains is simultaneously reduced. This precise parameter control resolves the trade-off between signal improvement and damage prevention

Inventive Principle:

Principle #35Parameter changes

3Manufacturing precision

If smaller magnetic grain sizes are used to increase areal density, then areal density increases, but magnetic anisotropy increases requiring higher temperatures

Engineering Contradiction:

Improveareal densityVSAvoidwriting temperature

Core Design Contradiction:

Manufacturing precisionVSTemperature

Solution Approach 1:

The patent modifies the capping layer composition parameters (Pt content in Co-BN) to enhance vertical exchange coupling strength. This parameter change allows smaller magnetic grains with higher anisotropy to be written at achievable temperatures by strengthening the exchange interaction that assists magnetization reversal, thereby enabling high areal density without requiring excessive temperatures

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 CoPtBN capping layer with Pt doping improves areal density capability by up to 3% and maintains effective readback signal, while minimizing etch damage and secondary grain issues.

Implementation Method 1

enhancing vertical exchange coupling

Methodology Applied

Scientific EffectExchange coupling:

Implementation Method 2

Methodology Applied

Scientific EffectCrystalline structure protection:

Data Source

PatentUS20250378850A1Magnetic recording medium with platinum-doped co-BN capping layer and magnetic recording apparatus for use therewith

Publication Date: 2025.12.11 WESTERN DIGITAL TECHNOLOGIES INC

AI summary

Various apparatuses, devices, methods, and media are disclosed for heat-assisted magnetic recording (HAMR) that, in some examples, provide a HAMR medium with a platinum-doped CO—BN capping layer. In one example, the HAMR medium includes a CoPtBN capping layer on a magnetic recording layer with Pt in the range of 5-12 atomic percentage (at. %). An atomic ratio of Co to Pt within the CoPtBN may be, e.g., in the range of 5 to 13. The BN in the CoPtBN may be, e.g., 22-30 mole percentage of the CoPtBN. The CoPtBN may have a face-centered cubic (FCC) crystalline structure. The HAMR medium may have various other layers, such as a substrate, a heatsink layer on the substrate, and a seed layer on the heatsink layer, with the magnetic recording layer on the seed layer. The seed layer may include MgO or MgO—TiO. An amorphous soft underlayer (SUL) may be provided.