Perpendicular Magnetic Recording Media Density and Corrosion
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Solution Overview
Problem
Perpendicular magnetic recording media suffer from poor scratch resistance in high RPM drives and poor corrosion performance in hot and humid environments due to high porosity, low density, and high surface roughness in the media film stack.
Innovation Solution
A perpendicular magnetic recording medium is developed with a substrate, an interlayer of hexagonal columns, and a magnetic layer deposited using a bias voltage to eliminate sub-grains and achieve perpendicular magnetic anisotropy, incorporating an amorphous soft underlayer and a granular magnetic layer with CoPtMo or CoPtCr alloys for improved density and corrosion resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high pressure sputtering is used to form Ru-containing layer and fill TiO2 or SiO2 in gaps, then perpendicular magnetic anisotropy is achieved, but porosity increases and density decreases
Solution Approach 1:
The patent changes the deposition pressure parameter from high pressure to low pressure (e.g., 3-10 mTorr) during sputtering of the Ru-containing layer and subsequent filling of TiO2/SiO2. This parameter change reduces porosity and increases density while maintaining the perpendicular magnetic anisotropy achieved through the hexagonal column structure.
2Reliability
If high pressure sputtering is used to form Ru-containing layer and fill TiO2 or SiO2 in gaps, then perpendicular magnetic anisotropy is achieved, but surface roughness increases
Solution Approach 1:
The patent changes the deposition pressure parameter from high pressure to low pressure (e.g., 3-10 mTorr) during sputtering. This parameter change produces a smoother surface finish while maintaining the hexagonal column structure that provides perpendicular magnetic anisotropy.
3Reliability
If high porosity and low density structure is used in media film stack, then perpendicular magnetic anisotropy is achieved, but scratch resistance deteriorates
Solution Approach 1:
The patent changes the deposition pressure from high to low (e.g., 3-10 mTorr), which increases density and reduces porosity. This creates a harder, more scratch-resistant surface while preserving the hexagonal column structure necessary for perpendicular magnetic anisotropy.
4Reliability
If high porosity and low density structure is used in media film stack, then perpendicular magnetic anisotropy is achieved, but corrosion performance deteriorates
Solution Approach 1:
The patent changes the deposition pressure from high to low (e.g., 3-10 mTorr), which reduces porosity and creates a denser, more corrosion-resistant structure. The low porosity prevents corrosive agents from penetrating the media film stack while maintaining the hexagonal column structure for perpendicular magnetic anisotropy.
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 enhances scratch resistance and corrosion performance while maintaining high areal recording density by reducing sub-grain growth, surface roughness, and exchange coupling, leading to improved media signal-to-noise ratio and bit error rate.
Implementation Method 1
The Ru-containing layer is generally sputtered at high pressure and TiO2 or SiO2 is filled the gap between columns in yet another high pressure process stage
Implementation Method 2
They are a Ruthenium (Ru)-containing layer having hexagonal Ru columns and TiO2 or SiO2 in the gaps between the Ru columns
Implementation Method 3
A perpendicular recording media has layers that make bits stand up and be perpendicular to the surface
Data Source
AI summary
An embodiment of the invention relates to a perpendicular magnetic recording medium comprising (1) a substrate, (2) an interlayer comprising hexagonal columns and (3) a magnetic layer, wherein the magnetic layer is deposited applying a bias voltage to the substrate such that the magnetic layer comprises magnetic grains having substantially no sub-grains within the magnetic layer, and the magnetic layer has perpendicular magnetic anisotropy.