MgTiOx Underlayer for FePt Media Growth
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Solution Overview
Problem
Current MgO underlayers used for growing FePt granular media in the (001) direction have limitations such as low deposition rates, poor thermal conductivity, high electrical insulation, and the production of MgO dust, which hinder the development of high-density perpendicular magnetic recording media.
Innovation Solution
The use of an electrically conductive MgTiOx underlayer replaces MgO, enabling direct current sputtering for increased deposition rates and allowing for higher temperature stability, while maintaining the (001) orientation of FePt grains, which is essential for heat-assisted magnetic recording.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If MgO underlayer is used to grow FePt in (001) direction, then FePt (001) orientation is achieved, but deposition rate is low and thermal conductivity is poor
Solution Approach 1:
The patent changes the material composition parameter of the underlayer from pure MgO to MgTiOx (magnesium titanate) with specific Ti content (5-35 atomic percent). This compositional parameter change transforms the material properties: MgTiOx maintains the (001) crystal orientation capability of MgO while simultaneously improving thermal conductivity and enabling DC sputtering for higher deposition rates.
Solution Approach 2:
The patent uses a composite oxide material MgTiOx that combines MgO and TiO2 in a specific ratio. This composite material integrates the beneficial properties of both components: MgO provides the (001) orientation template for FePt growth, while TiO2 contributes to improved thermal conductivity and electrical conductivity, enabling the use of DC sputtering.
2Manufacturing precision
If MgO underlayer is used, then FePt (001) orientation is achieved, but electrical insulation is high requiring RF sputtering
Solution Approach 1:
The patent changes the electrical conductivity parameter of the underlayer by introducing Ti into the MgO matrix. MgTiOx has significantly higher electrical conductivity than pure MgO, which allows the use of DC sputtering instead of RF sputtering. This parameter change simplifies the deposition process and reduces energy consumption.
3Reliability
If MgO underlayer is used, then FePt growth is enabled, but thermal conductivity is poor limiting heat dissipation
Solution Approach 1:
The patent employs MgTiOx composite material where TiO2 domains dispersed in MgO matrix provide enhanced thermal conduction pathways. The composite structure maintains the crystallographic template function for FePt (001) growth while the TiO2 phases improve overall thermal conductivity, enabling better heat dissipation during HAMR operation.
4Manufacturing precision
If MgO underlayer is used, then FePt (001) orientation is achieved, but MgO dust is produced during deposition
Solution Approach 1:
The patent changes the material composition from pure MgO to MgTiOx, which has different physical and chemical properties. MgTiOx exhibits reduced dust generation during sputtering deposition while maintaining the essential (001) orientation capability. The Ti incorporation modifies the material's mechanical properties and reduces dust formation.
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 MgTiOx underlayer facilitates efficient growth of FePt with strong perpendicular magnetic anisotropy, enhancing the performance of magnetic recording media by enabling direct current sputtering and improving thermal and electrical conductivity, thus overcoming the limitations of MgO underlayers.
Implementation Method 1
Since MgTiOx is electrically conductive (i.e., low resistivity), direct current (DC) sputtering can be used to achieve increases sputtering rates
Implementation Method 2
an MgTiOx underlayer is less expensive and is capable of withstanding higher temperatures than an MgO underlayer
Implementation Method 3
Since MgTiOx is electrically conductive (i.e., low resistivity), direct current (DC) sputtering can be used
Implementation Method 4
an MgTiOx underlayer to grow FePt granular media with (001) texture on glass substrates
Data Source
AI summary
A perpendicular magnetic recording medium, comprising: a substrate; a buffer layer deposited in a first orientation on top of the substrate; an underlayer deposited in a second orientation on top of the buffer layer, the underlayer comprising an electrically conductive oxide; and a magnetic recording layer deposited on top of the underlayer and having an axis of magnetic anisotropy substantially perpendicular to the surface thereof.