RhIr Alloy NFT with Rh Template Layer for TAMR Reliability
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Solution Overview
Problem
Current TAMR NFTs face challenges with oxidation susceptibility of Rh, leading to degradation and increased temperature, which affects reliability and ADC performance, and also suffer from defects like voids and cracks due to microstructure differences between the peg and NFT body, especially at peg thicknesses less than 40 nm.
Innovation Solution
A TAMR write head with a NFT made of a Au/RhIr alloy bilayer, where the upper RhIr layer has a peg with a rectangular shape and a body with increasing cross-track width, and a Rh underlayer is used to ensure uniform microstructure, minimizing oxidation and defect formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If Rh is used as the NFT material, then good optical properties are achieved, but oxidation susceptibility increases leading to degradation and temperature increase
Solution Approach 1:
The patent uses a RhIr alloy composite material that combines Rhodium and Iridium in specific ratios (30-70 at% Rh, 70-30 at% Ir). This composite maintains the excellent optical properties of Rh while Ir provides oxidation resistance and thermal stability, resolving the contradiction between optical performance and reliability.
Solution Approach 2:
The patent optimizes the compositional parameters of the alloy by controlling the atomic percentage of Rh and Ir components. By adjusting these parameters within specific ranges, the material achieves both good optical properties and oxidation resistance, transforming the trade-off into a controllable parameter optimization problem.
2Productivity
If peg thickness is reduced to increase ADC performance, then area density capability improves, but defect formation increases due to microstructure differences
Solution Approach 1:
The patent optimizes the peg thickness parameter within a specific range (20-40 nm) to balance ADC performance and defect resistance. By controlling this critical dimension parameter, the patent achieves high area density capability while maintaining structural integrity and minimizing defects.
Solution Approach 2:
The RhIr alloy composite provides uniform microstructure throughout the peg structure, eliminating the microstructure differences between peg and NFT body that cause defects. This compositional uniformity allows thin peg designs to maintain both high ADC performance and reliability.
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 solution enhances reliability and maintains acceptable ADC performance even at peg thicknesses less than 40 nm by preventing oxidation and reducing rupture defects, thereby stabilizing the NFT structure and improving overall device robustness.
Implementation Method 1
The near-field light is generated from plasmons excited by irradiation with light propagated through a metal layer. The peg generates near-field light efficiently by exciting surface plasmon (SP) or surface wave of free electrons bound at the metal-dielectric interface.
Implementation Method 2
Rh is susceptible to oxidation that leads to a degradation in plasmon efficiency and an undesirable increase in PG temperature. The present disclosure relates to a TAMR writer... comprised of a RhIr alloy having improved oxidation resistance compared with Rh
Implementation Method 3
NFT structure and geometry are engineered to enable efficient energy transfer from the waveguide to NFT body and peg, to excite local surface plasmon resonance, and to utilize a so-called lightning rod effect to further improve field confinement.
Data Source
AI summary
A near field transducer (NFT) with an upper RhIr layer having an Ir content from 20-80 atomic % and a lower Au layer is formed between a waveguide and main pole at an air bearing surface (ABS). The RhIr layer has a rod-like front portion (peg) up to height h1, and a substantially triangular shaped back portion (body) from h1 to height h2. In some embodiments, there is a Rh underlayer with a thickness from 10 Angstroms to 200 Angstroms between the upper and lower NFT layers, and extending from the ABS to h2 so that the RhIr layer has a substantially uniform microcrystalline structure throughout to prevent thermally induced rupture defects proximate to h1. Optionally, the Rh underlayer may have a front side at h1, and may further comprise a lower Al or Zr adhesion layer. Accordingly, there is improved device reliability.