HAMR Write Pole Nitrogen Plasma Passivation
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Solution Overview
Problem
In heat-assisted magnetic recording (HAMR) disk drives, the write pole is prone to oxidation due to its close proximity to the heated recording layer, leading to reduced performance and reliability.
Innovation Solution
A chemically-passivated write pole end is created by exposing it to a nitrogen plasma, along with the near-field transducer end, while protecting the magnetoresistive read head, and applying an optically transparent protective film to enhance corrosion resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the write pole is placed in close proximity to the recording layer to improve write performance, then the write field strength is enhanced, but the write pole becomes prone to oxidation due to heat exposure
Solution Approach 1:
The patent applies a chemically-passivated coating specifically to the write pole end that interfaces with the recording layer, while leaving other portions of the write pole unprotected. This localized treatment provides oxidation protection precisely where heat exposure is most severe, without compromising the magnetic performance of the write pole body.
Solution Approach 2:
The chemically-passivated coating acts as an intermediary layer between the write pole and the oxidizing environment. This protective barrier prevents direct contact between oxygen and the write pole material, eliminating the harmful oxidation effect while allowing the write pole to maintain its close proximity to the recording layer for effective writing.
2Reliability
If the write pole is exposed to nitrogen plasma to improve corrosion resistance, then oxidation protection is enhanced, but the manufacturing process complexity increases
Solution Approach 1:
The nitrogen plasma treatment is applied during the manufacturing process as a preliminary step before final assembly. By performing the chemical passivation early in the manufacturing sequence, the protective coating is established before the write pole is installed in the head, simplifying the overall process and avoiding the need for additional protection steps after assembly.
Solution Approach 2:
The patent utilizes nitrogen plasma, which changes the chemical parameters of the write pole surface by introducing nitrogen atoms that form protective nitride compounds. This parameter change at the surface level provides corrosion resistance without altering the bulk properties of the write pole material or requiring complex multi-step 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 solution significantly improves the corrosion resistance of the write pole, leading to enhanced recording performance and extended lifetime of the HAMR write heads by preventing oxidation.
Implementation Method 1
exposing it to a nitrogen plasma
Implementation Method 2
A chemically-passivated write pole end is created by exposing it to a nitrogen plasma
Implementation Method 3
applying an optically transparent protective film to enhance corrosion resistance
Implementation Method 4
light from a laser diode is coupled to a waveguide that guides the light to a near-field transducer (NFT)
Implementation Method 5
Sometimes, the metal structure of the NFT can create resonant charge motion (surface plasmons) to further increase intensity and disk heating
Implementation Method 6
Since it is known that the coercivity of the magnetic material of the recording layer is temperature dependent, one proposed solution to the thermal stability problem is heat-assisted magnetic recording (HAMR), wherein high-Ku magnetic recording material is heated locally during writing to lower the coercivity
Data Source
AI summary
A heat-assisted magnetic recording (HAMR) write head has a write pole with a chemically-passivated end that substantially prevents oxidation and thus improves corrosion resistance of the write pole. The write pole and near-field transducer (NFT) are supported on a slider and have their ends in a window region of the slider's disk-facing surface. The outer surface region of the write pole is chemically-passivated, preferably by exposure to a nitrogen plasma. The nitrogen plasma has no effect on the NFT end or on the magnetoresistive read head, which is protected because it is located in a non-window region of the slider's disk-facing surface. An optically transparent protective film is formed in the window over the passivated write pole end and NFT end.