Variable Overcoat for HAMR Near Field Transducer Protection
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Solution Overview
Problem
The harsh environment of heat-assisted magnetic recording (HAMR) processes, characterized by high temperatures and corrosive chemistries, leads to rapid wear of delicate structures like the near field transducer (NFT) and write pole, necessitating effective protective methods for these components.
Innovation Solution
The method involves depositing a first and second layer over a structure with a magnetic reader and writer, including a NFT, followed by a photoresist material layer exposure through both the bottom and top surfaces to create exposed regions, which are used to form a writer hard mask and etch the first layer, ultimately applying a variable overcoat with a disparate portion over the magnetic writer for enhanced protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a uniform thick overcoat is deposited to protect the NFT and write pole from corrosion and wear, then the protective reliability is improved, but the head-to-media spacing increases which degrades magnetic recording performance
Solution Approach 1:
The patent applies different overcoat thicknesses to different regions: a first thickness (e.g., 5-10 nm) over the reader region and a second, greater thickness (e.g., 15-30 nm) over the writer region including the NFT and write pole. This local differentiation provides enhanced protection where needed while maintaining minimal spacing where performance is critical.
Solution Approach 2:
The overcoat is segmented into at least two distinct layers with different thicknesses: a first overcoat layer over the reader and a second overcoat layer over the writer. This segmentation allows independent optimization of protection and performance for different functional regions of the magnetic head.
2Length of moving object
If no overcoat is used to maintain small head-to-media spacing, then the magnetic recording performance is maintained, but the NFT and write pole are exposed to corrosive chemistries and high temperatures leading to rapid wear
Solution Approach 1:
The patent provides localized protection by depositing greater overcoat thickness specifically over the writer region where the NFT and write pole are located, while maintaining thinner overcoat over the reader region. This ensures durability for exposed components without compromising overall head-to-media spacing.
Solution Approach 2:
The overcoat layers are deposited beforehand to create a protective barrier against the corrosive HAMR environment (high temperatures and corrosive chemistries) before the head undergoes operation, preventing rapid wear of the NFT and write pole from the outset.
3Reliability
If a variable overcoat with disparate thicknesses is formed, then the protective reliability is improved without increasing overall head-to-media spacing, but the manufacturing process complexity increases
Solution Approach 1:
The patent introduces a thickness dimension variation in the overcoat structure, transitioning from a uniform 2D layer to a 3D variable thickness structure. This allows enhanced protection in specific regions while maintaining minimal overall height, achieving both protection and performance goals.
Solution Approach 2:
The patent changes the thickness parameter of the overcoat layer across different spatial regions. By controlling deposition parameters (such as shadow masking, selective deposition, or varying deposition time), the process creates variable thickness profiles to optimize both protection and spacing.
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 provides improved thermal, chemical, and mechanical reliability for the NFT and write pole by forming a variable overcoat that protects these components without increasing the head-to-media spacing, thus maintaining performance and preventing corrosion and wear.
Implementation Method 1
exposing the photoresist material layer to radiation through the bottom surface of the photoresist material layer via the NFT to form a first exposed region
Implementation Method 2
exposing the photoresist material layer to radiation through the top surface of the photoresist material layer to form a second exposed region
Implementation Method 3
the optical waveguide is configured to transmit radiation to the NFT
Data Source
AI summary
Methods that include depositing a first layer over the entire surface of a structure, the structure having a magnetic reader and a magnetic writer, wherein the magnetic reader and the magnetic writer are positioned adjacent to each other on a substrate and the magnetic writer includes a near field transducer (NFT); depositing a second layer over the entire surface of the first layer; depositing a photoresist material layer over the entire surface of the second layer, the photoresist material layer having a bottom surface in contact with the second layer and an opposing top surface; exposing the photoresist material layer to radiation through the bottom surface of the photoresist material layer via the NFT to form a first exposed region; and exposing the photoresist material layer to radiation through the top surface of the photoresist material layer to form a second exposed region.