CuW Sacrificial Layer for Magnetic Recording Head Fabrication

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Solution Overview

Problem

Current magnetic recording head fabrication processes face challenges in achieving high data-recording capabilities due to low mill resistance and non-uniformity in materials like copper, which affects the formation of write elements and leads to erosion and poor layer growth.

Innovation Solution

A sacrificial metal alloy layer with moderate mill resistance, such as copper-tungsten (CuW), is used in the fabrication process, providing improved mill resistance and wet-etchability to prevent erosion and ensure optimal formation of write pole structures with suitable wall angles.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If copper is used as a sacrificial layer material, then ease of manufacture is improved, but mill resistance is insufficient leading to erosion and non-uniform layer formation

Engineering Contradiction:

Improveease of manufactureVSAvoidmill resistance

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent applies composite materials by combining copper with tungsten to create a CuW alloy sacrificial layer. This composite material integrates the beneficial properties of both elements: copper provides good etchability and electrical conductivity, while tungsten contributes high mill resistance and structural stability. The resulting alloy maintains ease of manufacture through standard deposition processes while achieving the required mill resistance and uniformity for high-density recording head fabrication

Inventive Principle:

Principle #40Composite materials

2Ease of manufacture

If copper is used as a sacrificial layer material, then ease of manufacture is improved, but uniformity deteriorates affecting write element formation

Engineering Contradiction:

Improveease of manufactureVSAvoiduniformity

Core Design Contradiction:

Ease of manufactureVSStability of the object's composition

Solution Approach 1:

The CuW alloy creates a composite material with enhanced compositional stability. The tungsten component acts as a stabilizing agent that prevents the non-uniformity issues inherent in pure copper. This composite structure ensures consistent material properties throughout the sacrificial layer, enabling uniform write element formation and consistent wall angles across the recording head structure

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent applies parameter changes by modifying the material composition from pure copper to a copper-tungsten alloy with specific atomic percentages (e.g., 80-20, 70-30, or 60-40 Cu:W). This compositional parameter change fundamentally alters the material's mill resistance and uniformity characteristics while maintaining compatibility with existing fabrication processes, thereby achieving both ease of manufacture and compositional stability

Inventive Principle:

Principle #35Parameter changes

3Manufacturing precision

If moderate mill resistance material is used, then manufacturing precision is improved, but wet etchability may deteriorate

Engineering Contradiction:

Improvemill resistanceVSAvoidwet etchability

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent resolves this contradiction by precisely controlling the compositional parameters of the CuW alloy. By adjusting the atomic percentage of tungsten (typically 20-40%), the material achieves an optimal balance where sufficient mill resistance is obtained while retaining adequate wet etchability. The copper component ensures the alloy remains wet-etchable, while the tungsten content provides the necessary mill resistance for precise write element formation

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The composite CuW alloy structure enables simultaneous achievement of moderate mill resistance and good wet etchability. The material composition is designed so that copper provides the etchability needed for sacrificial layer removal, while tungsten contributes the mill resistance required for manufacturing precision. This composite approach allows both properties to coexist in a single material system

Inventive Principle:

Principle #40Composite materials

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 use of CuW alloy enhances the data-recording capabilities by maintaining the integrity of the write pole tip during milling and allowing for the formation of trapezoidal shapes with optimal wall angles, improving recording density without affecting subsequent layer growth.

Implementation Method 1

A sacrificial metal alloy layer, which is wet etchable and has a moderate mill resistance, is deposited over a substrate

Methodology Applied

Scientific EffectWet etching:

Data Source

PatentUS10026423B1Moderate mill resist and wet-etchable alloy for use in a recording head fabrication process

Publication Date: 2018.07.17 SEAGATE TECH LLC

AI summary

A method of forming a magnetic recording head. The method includes depositing a sacrificial metal alloy layer, which is wet etchable and has a moderate mill resistance, over a substrate. The method also includes depositing a write pole layer over the sacrificial metal alloy layer. The write pole layer has a bottom surface and a top surface opposite the bottom surface. A portion of the bottom surface of the write pole layer is in contact with the sacrificial metal alloy layer.