Self-Aligned Optical Side Shields for TAMR Head Plasmon Efficiency
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Solution Overview
Problem
Current TAMR write heads face challenges in maintaining thermal stability and coercivity due to the size reduction of magnetic particles, which is exacerbated by asymmetrical optical side shield (OSS) placement leading to suppressed surface plasmon excitations and reduced optical efficiency.
Innovation Solution
A self-aligned optical side shield (SA-OSS) method is introduced to uniformly control the gap between the near-field transducer (NFT) and OSS, ensuring precise and consistent positioning across wafers, thereby improving down-track and cross-track thermal gradients and enhancing near-field energy concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the magnetic fine particles are made smaller to reduce boundary irregularities and enhance recording density, then the recording density is improved, but the thermal stability of magnetization deteriorates due to reduced particle volume
Solution Approach 1:
The patent applies thermal assistance by temporarily changing the temperature parameter of the magnetic recording medium during the writing process. A laser heats the medium to reduce coercivity, enabling writing on high-KU particles that would otherwise be too stable to write. This parameter change (temperature) allows the system to achieve both high recording density and maintain thermal stability through the use of high-anisotropy particles.
2Stability of the object's composition
If KU is increased to improve thermal stability of magnetization, then the thermal stability is improved, but the coercivity increases making writing difficult
Solution Approach 1:
The patent employs periodic thermal assistance where a laser pulse is applied temporarily during the writing process to reduce coercivity, followed by cooling to restore high coercivity for thermal stability. This periodic action (heating-cooling cycle) allows the medium to be written when needed while maintaining stability during storage.
3Ease of manufacture
If asymmetrical OSS placement is used in conventional fabrication, then the fabrication process is simpler, but the surface plasmon excitations are suppressed and optical efficiency is reduced
Solution Approach 1:
The patent employs a self-aligned fabrication process where the OSS structures are automatically positioned relative to the waveguide and NFT during fabrication, eliminating the need for complex separate alignment steps. The OSS are formed in a self-aligned manner that ensures symmetrical placement, improving plasmon excitation efficiency while maintaining fabrication feasibility through integrated process design.
4Ease of manufacture
If conventional photolithography is used for OSS fabrication, then the manufacturing process is established, but asymmetrical side gaps are created between OSS and NFT
Solution Approach 1:
The patent introduces a self-aligned fabrication process that uses the waveguide and NFT structures themselves as alignment references for forming the OSS. This intermediary alignment approach ensures that the OSS are positioned symmetrically relative to the NFT, eliminating the asymmetries caused by conventional photolithography while maintaining compatibility with existing manufacturing processes.
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 self-aligned OSS feature enhances the thermal activation of magnetic recording media by uniformly sharpening the heated region, improving writing performance and reliability by eliminating asymmetries and optimizing plasmon energy transfer.
Implementation Method 1
The waveguide-propagated electromagnetic radiation is transferred to the NFT by electromagnetic coupling
Implementation Method 2
the radiation in the waveguide couples to a device called a plasmon generator by electromagnetic coupling where it excites plasmon modes in the generator
Implementation Method 3
The optical radiation coupled by the waveguide to the plasmon generator is in turn transferred to the recording medium via the near-field energy of the plasmons produced by the generator, and this energy locally heats the surface of recording media
Implementation Method 4
this energy locally heats the surface of recording media
Implementation Method 5
Heat is applied locally to a magnetic recording medium immediately before applying a writing magnetic field, particularly while using a magnetic material having a large value of KU. The heat then effectively lowers the medium's coercivity
Data Source
AI summary
An optically shielded (thermally assisted magnetic recording (TAMR) head comprises a perpendicular magnetic recording (PMR) write head and a near-field transducer (NFT) having an emerging peg at the air-bearing surface (ABS). Self-aligned optical side shields (SA-OSS) are formed using a self-aligning process that positions the shields symmetrically relative to the emergent peg of the NFT. As a result of the symmetric positioning the down-track and cross-track near-field and near-field gradients are significantly sharpened.