Near Field Transducer Manufacturing for HAMR Reliability
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Solution Overview
Problem
Near-field transducers (NFTs) in heat-assisted magnetic recording (HAMR) devices face degradation due to temperature rises and mechanical stress, leading to reduced reliability and service life, as well as issues with critical dimension variability and peg-disc separation.
Innovation Solution
The method involves forming NFTs with a disc and peg structure, where the peg extends towards the recording media, and a barrier layer is formed adjacent to the back edge of the rod, with the disc material deposited in a void defined by a hard mask, and polished to create a planar surface, enhancing thermal robustness and alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the NFT structure is simplified for easier manufacture, then manufacturing precision and thermal robustness deteriorate due to temperature rises and mechanical stress
Solution Approach 1:
The NFT is divided into distinct functional segments: a peg portion extending toward the recording medium and a disc portion with optical resonator structures. This segmentation allows each part to be optimized independently for its specific function while maintaining overall structural integrity under thermal and mechanical stress.
Solution Approach 2:
The optical resonator structures (including the disc and associated features) are integrated within or adjacent to the peg structure, creating a nested configuration where the resonator is positioned within the overall NFT assembly. This nesting achieves complex functionality without requiring separate discrete components, thereby maintaining manufacturing precision.
2Ease of manufacture
If the NFT structure is simplified for easier manufacture, then reliability deteriorates due to peg-disc separation and reduced service life
Solution Approach 1:
The peg and disc portions are merged into a single integrated NFT structure formed through coordinated deposition and etching processes. This merging eliminates the risk of peg-disc separation by ensuring continuous material continuity between the two functional regions, thereby enhancing reliability and service life.
Solution Approach 2:
The method performs preliminary actions by forming the complete NFT structure (peg and disc portions) in a coordinated sequence before final assembly. The peg is formed first, then the disc portion is deposited and patterned in relation to the peg, ensuring proper alignment and structural integrity from the outset.
3Productivity
If critical dimensions are reduced for higher areal density, then manufacturing precision deteriorates due to variability
Solution Approach 1:
The method controls critical dimensions by adjusting deposition parameters (thickness, composition) and etching parameters (selectivity, depth) to achieve the desired small dimensions while maintaining manufacturing precision. The peg and disc dimensions are controlled through these parameter optimizations rather than simple geometric reduction.
Solution Approach 2:
Traditional mechanical measurement and adjustment methods are replaced with deposition-based and etching-based dimensional control. The critical dimensions are defined by controlled material removal and addition processes rather than mechanical machining, reducing variability at small scales.
4Use of energy by moving object
If the NFT is exposed to higher temperatures for HAMR operation, then thermal robustness worsens leading to degradation
Solution Approach 1:
The NFT structure incorporates materials and geometries with local quality optimized for thermal performance. The peg and disc portions use materials selected for their thermal stability and conductivity characteristics, allowing the structure to withstand the high temperatures required for heat-assisted magnetic recording while maintaining structural integrity.
Data Source
AI summary
Methods of forming a NFT the methods including forming a hard mask positioned over at least a portion of the rod, the hard mask including at least one layer; patterning a resist mask over the hard mask, the resist mask having an edge positioned over at least a portion of the rod; etching a portion of the hard mask to expose a back edge of the rod and to form a back edge of the hard mask, wherein the back edge of the rod is equivalent to the back edge of the peg; and wherein a forward portion of the rod which is the portion of the rod forward of the back edge is covered by the hard mask; forming a disc mask including a void configured to form a disc of a NFT, the disc mask being formed over at least a portion of the hard mask so that the exposed back edge of the rod is within the void configured to form the disc; etching an area exposed in the void of the disc mask to remove both a rear portion of the rod and the surrounding dielectric up to the back edge of the hard mask edge; depositing a disc material in the etched void, wherein the back edge of the hard mask defines the front edge of the disc and the back edge of the rod is in contact with the front edge of the disc; and polishing the deposited disc material to form a top surface substantially planar with the top of the forward rod portion.