Tri-Layered Hard Mask for Wraparound Shield Write Head Precision

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Solution Overview

Problem

Current manufacturing processes for magnetic recording write heads face challenges in achieving precise control over shield thickness and taper characteristics, leading to variations in performance and susceptibility to corrosion, especially at smaller geometries.

Innovation Solution

The implementation of a tri-layered hard mask using NiCr/Ir/NiCr layers in conjunction with 193 nm DUV photolithography technology, eliminating the need for CMP processes and enabling better control over Leading Edge Shield and Leading Edge Taper formation, with a non-magnetic RIE stop layer for improved precision and corrosion resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If traditional manufacturing processes are used for write head shield formation, then production can be maintained, but shield thickness uniformity and taper precision deteriorate due to process variations

Engineering Contradiction:

Improveshield thickness uniformityVSAvoidprocess variation susceptibility

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The manufacturing process is segmented into distinct sequential steps: depositing first and second hard mask layers with different etch selectivities, forming the shield structure, then removing masks in sequence. This segmentation allows each layer to serve a specific function in controlling shield thickness and taper, improving precision while reducing process variation susceptibility.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention changes the material parameters by using a specific combination of hard mask layers with different etch selectivities (e.g., chromium oxide and silicon nitride). By selecting materials with contrasting etch rates, the process achieves precise control over shield thickness and taper characteristics, resolving the contradiction between manufacturing precision and reliability.

Inventive Principle:

Principle #35Parameter changes

2Length of moving object

If shield geometry is reduced to achieve smaller write head dimensions, then areal density improves, but corrosion resistance deteriorates

Engineering Contradiction:

Improvewrite head dimensionVSAvoidcorrosion susceptibility

Core Design Contradiction:

Length of moving objectVSObject-affected harmful factors

Solution Approach 1:

The invention employs a composite hard mask structure with multiple layers (e.g., chromium oxide layer and silicon nitride layer) that work together to protect the shield geometry. This composite approach enables the formation of smaller, more precise shield features while maintaining corrosion resistance through the protective properties of the hard mask materials.

Inventive Principle:

Principle #40Composite materials

3Ease of manufacture

If CMP processes are used for shield formation, then manufacturing simplicity is maintained, but precision and corrosion resistance worsen

Engineering Contradiction:

Improveprocess simplicityVSAvoidtaper characteristic precision

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The invention replaces the mechanical CMP (chemical mechanical polishing) process with a deposition-based approach using hard mask layers. Instead of mechanically removing material to achieve the desired shield geometry, the process deposits precise layers of material with controlled thicknesses, eliminating CMP-induced variations and improving taper precision while maintaining manufacturing feasibility.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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

This approach results in improved uniformity and precision of shield thickness and taper characteristics, enhancing the performance of the wraparound shield write head by reducing process variations and avoiding corrosion issues, thereby improving areal density and write field strength.

Implementation Method 1

depositing a first hard mask layer of chromium oxide over the collimated pole pieces and leading edge of the return pole; depositing a second hard mask layer of silicon nitride over the first hard mask layer

Methodology Applied

Scientific EffectPhysical Vapour Deposition: Physical Vapour Deposition

Implementation Method 2

193 nm DUV photolithography technology

Methodology Applied

Scientific EffectPhotography: Photography

Data Source

PatentUS8801943B2Method for manufacturing wraparound shield write head using hard masks

Publication Date: 2014.08.12 WESTERN DIGITAL TECHNOLOGIES INC

AI summary

The present disclosure describes a method for manufacturing a full wraparound shield damascene write head through the implementation of a three layered (tri-layered) hard mask. According to an embodiment of the invention, the various layers of hard mask are used for different purposes during the formation of a write head. The wraparound shield head of the present invention exhibits improved physical characteristics that further result in improved performance characteristics. Use of the hard mask layers according to the present invention allows for use of manufacturing processes that can be more closely controlled than those processes used in other processes. For example, smaller dimension lithographic techniques can be used. Also, reliance on certain CMP processes is not necessary where the use of CMP processes is not as well-controlled as deposition or lithographic techniques as is possible using the present invention.