HAMR Media Templated Growth for Grain Size Control
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Solution Overview
Problem
Current data storage systems using heat-assisted magnetic recording (HAMR) face challenges in achieving high areal data storage densities due to limitations in controlling grain size and distribution of magnetic grains, which affect signal-to-noise ratio and thermal stability.
Innovation Solution
The use of pre-defined topographical features, such as patterned surfaces and nanoparticle arrays, as templates to control the growth of high anisotropy HAMR media, allowing for precise control of grain size and distribution, and the growth of chemically distinct and isolated columnar grains at elevated temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional deposition methods are used to form magnetic grains, then the grain size distribution is wide (above 10-15%), but using templated growth methods enables precise control of grain size distribution to below 10-15%
Solution Approach 1:
A template structure is formed in advance on the substrate before depositing the magnetic material. The template pre-defines the grain size and distribution pattern, allowing precise control of magnetic grain formation without requiring complex in-situ manipulation during deposition. This preliminary structuring enables the magnetic material to self-organize into desired grain patterns.
Solution Approach 2:
The template acts as an intermediary structure that mediates between the substrate and the magnetic material. It provides a controlled interface that directs the deposition process, enabling precise grain size control while simplifying the overall manufacturing process by using a removable or integrated template rather than complex real-time control systems.
2Productivity
If magnetic grain size is reduced to increase areal density, then storage density improves, but thermal stability and coercivity may deteriorate
Solution Approach 1:
The template structure creates local variations in the substrate surface that induce localized strain fields during magnetic material deposition. These local strain fields enhance the magnetic anisotropy energy, providing thermal stability to ultrathin magnetic grains. Different regions of the template can be designed to provide specific local conditions for optimal grain stability.
Solution Approach 2:
The templated growth method changes the physical parameters of the substrate surface (such as surface energy, roughness, and strain state) to optimize magnetic material properties. By controlling these substrate parameters, the magnetic grains achieve enhanced coercivity and thermal stability despite their reduced size, enabling higher areal densities without sacrificing reliability.
3Strength
If high temperature deposition is used to form chemically ordered L10 phase, then magnetic anisotropy improves, but the template must withstand temperatures as high as 700°C
Solution Approach 1:
The template is constructed from composite materials or multi-layer structures that combine materials with different thermal stability characteristics. This allows the template to withstand high deposition temperatures while maintaining its structural integrity and patterning capabilities. The composite structure can be designed to have thermal expansion coefficients matched to the substrate and magnetic layer to minimize thermal stress.
Solution Approach 2:
The template structure is designed with inherent thermal management features that cushion against high temperature effects before they can damage the template or affect the magnetic material quality. This may include thermal barriers, heat sinks, or temperature-controlled deposition zones that protect the template during the high-temperature chemical ordering 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
This approach enables the reduction of grain size distribution to below 10-15%, improving areal densities and thermal stability, while maintaining high coercivity and remnant magnetization, thus enhancing the performance of HAMR media.
Implementation Method 1
By preserving the surface properties of these features, they introduce heteroepitaxial strain resulting in the high anisotropy direction aligned out-of-plane
Implementation Method 2
Depositions are done at elevated temperatures in the range 300 to 700° C. to ensure that the highly anisotropic (Ku) chemically ordered L10 phase is formed in a chemical ordering transition from an initially isotropic A1 phase
Data Source
AI summary
Methods are disclosed for increasing areal density in Heat Assisted Magnetic Recording (HAMR) data storage systems by controlling the media layer grain size, grain size distribution, and pitch via templating techniques that are compatible with the high temperature HAMR media deposition. Embodiments include using current HAMR media seed layers as well as additionally introduced interlayers for the templating process. Topographic as well as chemical templating methods are disclosed that may employ nanoimprint technology or nanoparticle self-assembly among other patterning techniques.