Laminated Plasmon Generator for TAMR Reliability
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Solution Overview
Problem
Current thermally assisted magnetic recording (TAMR) technologies face challenges in achieving a narrow optical spot size of 20 nm or less with high optical efficiency and reliability, particularly due to corrosion and migration issues with noble metals used in plasmon generators (PGs).
Innovation Solution
A laminated plasmon generator structure is developed, comprising alternating layers of high optical efficiency metals like Au, Ag, Cu, and alloys with low atom mobility metals or dielectric materials, which are non-planar and fill a cavity within a dielectric layer, featuring a narrow peg portion and a wider second portion, enhancing optical spot confinement and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If noble metals (Au, Ag, Cu) are used in plasmon generator to achieve high optical efficiency, then optical efficiency is improved, but reliability deteriorates due to corrosion and migration issues
Solution Approach 1:
The patent uses composite material structures where noble metal layers (Au, Ag, Cu) are combined with protective metal layers (Pt, Pd, Rh, Ir) or dielectric layers to form laminated structures. This composite approach maintains the high optical efficiency of noble metals while the protective layers prevent corrosion and migration, thereby improving reliability without sacrificing optical performance.
Solution Approach 2:
The patent applies different material properties to different regions of the plasmon generator. The noble metal layers are positioned where optical efficiency is critical, while protective layers are applied specifically at regions prone to corrosion and migration. This localized quality differentiation allows the system to optimize both optical performance and reliability in their respective zones.
2Manufacturing precision
If plasmon generator structure is optimized to achieve narrow optical spot size of 20 nm or less, then spot size is improved, but manufacturing complexity increases
Solution Approach 1:
The plasmon generator is segmented into multiple thin layers (noble metal layers alternating with protective metal or dielectric layers) rather than using a single bulk structure. This segmentation allows precise control over the optical spot size by adjusting individual layer thicknesses and compositions, achieving 20 nm or less spot size while managing manufacturing complexity through modular layer-by-layer fabrication.
Solution Approach 2:
The patent transitions from two-dimensional planar structures to three-dimensional laminated structures with controlled thicknesses in the vertical dimension. By optimizing the thickness of each layer in the z-direction, the patent achieves precise control over the optical spot size in the lateral dimensions, effectively using the third dimension to control two-dimensional optical properties.
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 laminated PG structure achieves scalable and reliable optical spot sizes, improving areal density and reliability by preventing grain growth and corrosion, while maintaining high optical efficiency and low resistive heating.
Implementation Method 1
Through evanescent coupling, the optical energy in the WG can be efficiently transferred to EPG mode
Implementation Method 2
TAMR involves raising the temperature of a small region of the magnetic medium to near its Curie temperature... optical power from a light source is converted into localized heating in a recording medium during a write process
Data Source
AI summary
A plasmon generator (PG) is disclosed with a laminated structure of non-planar X and Y layers formed between a waveguide and write pole. Each X layer is made of a noble metal such as Au while each Y layer is a non-noble metal or dielectric material to improve durability. As a result, the PG has a peg portion at an air bearing surface with improved reliability compared with pegs made entirely of a noble metal. Non-planarity of X and Y layers improves diffusion of Y material between X grains thereby minimizing X grain growth to enhance thermal stability. The laminated PG is formed by a process sequence that involves forming and filling a cavity, and concludes with a chemical mechanical polish process to form a planar top PG surface that faces a write pole leading side.