Patterned Seed Layer Fabrication for Magnetic Recording Media
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Magnetic hard disk drives face challenges in recording capacity due to the superparamagnetic effect, and patterned media fabrication methods struggle with flyability, topographical features affecting aerodynamics, and high background noise from stray fields, making cost-effective mass production difficult.
Innovation Solution
Growing vertical magnetic grains on a patterned seed layer with a matrix of islands separated by non-magnetic regions, allowing for self-organized magnetic and non-magnetic material deposition without additional planarization or trench removal processes, which minimizes topographical differences and reduces noise from non-magnetic boundaries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the magnetic recording layer is initially deposited as a continuous film and then patterned using lithographic processes, then the magnetic islands can be defined with precise dimensions, but the finished media has topographical features that affect the aerodynamics of the read/write head (flyability problem)
Solution Approach 1:
The invention applies preliminary patterning to the seed layer before magnetic layer deposition. The seed layer is patterned into islands and trenches in advance, and then the magnetic layer is deposited conformally over this pre-patterned structure. This preliminary action allows the magnetic islands to inherit the precise patterning from the seed layer while avoiding post-deposition planarization steps that would compromise flyability.
Solution Approach 2:
The invention segments the seed layer into discrete islands separated by trenches, with different crystallographic orientations. The <100> oriented seed islands promote vertical magnetic grain growth, while the <110> oriented seed in trenches promotes non-magnetic material growth. This segmentation creates magnetically isolated islands with controlled dimensions and properties without requiring additional planarization.
2Ease of manufacture
If reactive-ion-etching is used to remove portions of the magnetic layer to create patterned media, then the magnetic islands can be defined, but the magnetism of the remaining magnetic islands is affected (causing softening, loss of magnetic moment)
Solution Approach 1:
The invention performs the patterning action on the seed layer before magnetic layer deposition, rather than etching the magnetic layer itself. The seed layer is patterned using lithographic and etch processes, then the magnetic layer is deposited conformally. This preliminary patterning of the seed layer avoids direct etching of the magnetic material, preserving its magnetic properties while still achieving the desired island structure.
Solution Approach 2:
The seed layer acts as an intermediary layer between the substrate and the magnetic recording layer. It receives the patterning processes (lithography and etching) that define the island structure, then transfers this pattern to the magnetic layer through conformal deposition. This intermediary role protects the magnetic layer from direct exposure to harsh etching processes that would compromise its magnetic stability.
3Ease of manufacture
If material is deposited onto the sidewalls of the islands, then the islands are formed, but coupling of adjacent islands occurs via the trenches due to material deposition on sidewalls
Solution Approach 1:
The invention applies local quality by creating different crystallographic orientations in different spatial regions. The seed layer islands have <100> orientation promoting vertical magnetic growth, while the trench regions have <110> orientation promoting non-magnetic material growth. This local differentiation ensures that material deposited in trench regions does not become magnetically active, preventing coupling between adjacent magnetic islands.
Solution Approach 2:
The invention changes the crystallographic orientation parameter of the seed layer in different regions to control material growth properties. By orienting the seed layer <100> in island regions and <110> in trench regions, the patent controls whether deposited material becomes magnetic or non-magnetic, thereby preventing unwanted magnetic coupling while maintaining island formation.
4Reliability
If the magnetic recording layer is created as an ordered array of pre-defined highly uniform islands, then the superparameteragnetic effect is delayed, but write synchronization between the write head position and the position of the islands is necessary, increasing system complexity
Solution Approach 1:
The invention applies self-service by creating media structures that inherently provide their own positioning references. The periodic pattern of magnetic islands and non-magnetic trenches creates detectable transitions that automatically indicate island positions to the read/write head. This self-positioning capability reduces the complexity of external synchronization systems while maintaining the magnetic stability benefits of patterned media.
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 enhances recording density and signal-to-noise ratio by ensuring magnetic grains align with bit boundaries, reducing the need for additional processing steps and minimizing overgrowth, thus achieving a higher utilization factor comparable to continuous perpendicular recording media.
Implementation Method 1
The first seed material is selected to initiate growth of magnetic material, and the second seed material is selected to initiate growth of non-magnetic material
Implementation Method 2
magnetic material is grown on the first seed material, and non-magnetic material is grown on the second seed material
Data Source
AI summary
Patterned media and associated methods of fabrication are provided in which vertical magnetic grains are grown on a patterned seed layer. The patterned seed layer includes a matrix of islands of a first seed material. Each island of first seed material is separated from other islands by a region of second seed material. The first seed material is selected to initiate growth of magnetic material, and the second seed material is selected to initiate growth of non-magnetic material. Subsequently, magnetic material is grown on the first seed material and non-magnetic material is grown on the second seed material. Deposition may be simultaneously. The magnetic and non-magnetic materials form well-defined vertical columns over the first and second seed materials respectively. Thus, each island behaves as an isolated magnetic unit, which switches independently from its neighbor units, which are magnetically separated by the non-magnetic material.