HAMR Media Sacrificial Layer Etching for Lower Head-to-Media Spacing
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Solution Overview
Problem
The challenge in heat-assisted magnetic recording (HAMR) systems is the high roughness of the media interface due to magnetic grain topology, leading to increased head-to-media spacing and degraded recording performance, which is exacerbated by the use of a thick carbon overcoat to achieve smoothness.
Innovation Solution
Incorporating a sacrificial layer made of non-magnetic material within the capping layer, which is selectively etched to planarize the capping layer and reduce roughness, maintaining the magnetic grain structure integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a thick carbon overcoat is used to achieve smoothness at the media interface, then surface smoothness is improved, but head-to-media spacing increases and recording performance degrades
Solution Approach 1:
A sacrificial layer is deposited beforehand on the magnetic recording layer before the capping layer and overcoat are applied. This sacrificial layer serves as a placeholder that allows subsequent etching to selectively remove material from peaks while preserving valleys, achieving smoothness in advance rather than requiring a thick overcoat
Solution Approach 2:
The invention changes the physical and chemical parameters of the media interface by introducing a sacrificial layer with specific etch selectivity. Through controlled etching processes, the surface topology is transformed from rough to smooth by differential removal of material based on local composition variations
2Length of moving object
If the media interface roughness is reduced to minimize head-to-media spacing, then recording performance is improved, but the magnetic grain structure may be compromised
Solution Approach 1:
The sacrificial layer is strategically positioned only at grain boundaries rather than uniformly distributed. This local placement allows etching to selectively smooth peak regions while preserving the magnetic grain structure in the valleys, achieving surface smoothness without compromising magnetic integrity
Solution Approach 2:
The sacrificial layer acts as an intermediary material that facilitates the smoothing process. It is deposited on the magnetic layer, allows selective etching to occur, and then is partially removed to reveal the smoothed magnetic grain structure underneath, protecting it during the process
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 results in a smoother media interface, allowing for thinner overcoat layers, reduced head-to-media spacing, and improved magnetic recording performance with higher signal-to-noise ratio and glide yield.
Implementation Method 1
selectively etched to planarize the capping layer and reduce roughness
Data Source
AI summary
Various apparatuses, systems, methods, and media are disclosed to provide a heat-assisted magnetic recording (HAMR) medium that includes a sacrificial layer and corresponding etching processes to minimize head to media spacing. The medium may include the sacrificial layer and a capping layer where each of the layers is etched to reduce roughness. The sacrificial layer is configured to ensure an etch rate that allows for selective etching and may be deposited on the capping layer and after etching, may remain along grain boundaries of the capping layer. The remaining portions of the sacrificial layer may form a discontinuous layer, including layer segments positioned along grain boundaries of the capping layer. The sacrificial layer may be made of non-magnetic materials different from the materials of the capping layer or materials of an overcoat layer deposited on the etched capping layer.