Perpendicular Magnetic Recording Medium Three-Layer Ground Structure
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Solution Overview
Problem
The existing perpendicular magnetic recording medium faces challenges in achieving higher recording density due to noise issues, corrosion, and low shock resistance, particularly with the second ground layer having a low film density and rough structure, which affects the magnetic recording layer's stability and performance.
Innovation Solution
A three-layer ground structure is introduced, where the first and second ground layers contain ruthenium with varying gas pressures for sputtering, and the third ground layer is a high-density metal layer with an hcp structure, formed at a low pressure to prevent corrosion and enhance shock resistance, while maintaining crystal orientation and particle fineness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a two-layer ground structure is used to promote finer magnetic particles and isolation, then crystal orientation and particle fineness are improved, but film density decreases and corrosion resistance deteriorates
Solution Approach 1:
The ground layer is divided into three distinct layers (first ground layer, second ground layer, third ground layer) with different sputtering conditions and functions. The first and second ground layers use high-pressure sputtering to promote crystal orientation and particle isolation, while the third ground layer uses low-pressure sputtering to form a high-density corrosion-resistant barrier, thereby resolving the contradiction between manufacturing precision and reliability
Solution Approach 2:
Each ground layer is assigned different local properties: the first and second ground layers have properties optimized for crystal growth and particle formation (high-pressure sputtering), while the third ground layer has properties optimized for corrosion resistance (low-pressure sputtering with higher density). This local differentiation allows each layer to perform its specific function optimally without compromising the overall system
2Manufacturing precision
If the second ground layer is formed with high gas pressure to improve crystal orientation, then magnetic particle isolation is enhanced, but film density decreases and shock resistance deteriorates
Solution Approach 1:
The ground layer is segmented into three layers with different sputtering pressures. The second ground layer uses high gas pressure to achieve excellent crystal orientation and particle isolation, while the third ground layer uses low gas pressure to form a dense, shock-resistant protective layer, thereby resolving the contradiction between manufacturing precision and strength
Solution Approach 2:
The solution adds a third layer to the existing two-layer structure, transitioning from a two-dimensional optimization problem to a three-dimensional solution. This additional layer provides a new dimension for optimizing shock resistance without compromising the crystal orientation achieved by the second layer
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 three-layer structure improves crystal orientation, reduces noise, and increases coercive force, achieving finer magnetic particles and better isolation, while preventing corrosion and enhancing shock resistance, thus improving the recording density and reliability of the magnetic recording medium.
Implementation Method 1
a first ground layer on a side away from the magnetic recording layer is first formed by sputtering under an atmospheric gas at a predetermined pressure, and a second ground layer on a side near the magnetic recording layer is then formed by sputtering under an atmospheric gas at a pressure higher than the predetermined pressure
Data Source
AI summary
An object is to provide a perpendicular magnetic recording medium including a ground layer that prevents corrosion, while achieving a primary object of promoting finer magnetic particles of a magnetic recording layer and isolation of these magnetic particles.The structure of a perpendicular magnetic recording medium 100 according to the present invention includes, at least on a base 110: a magnetic recording layer 122 on which a signal is recorded; a ground layer 118 provided below the magnetic recording layer; a non-magnetic layer 116 for controlling crystal orientation of the ground layer; and a soft magnetic layer 114 provided below the non-magnetic layer. The ground layer 118 is configured to have three layers including, in an order from bottom, a first ground layer 118a and a second ground layer 118b that contain ruthenium, and a third ground layer 118c that contains a metal. A gas pressure at film formation by sputtering for the second ground layer 118b is the highest among those for the above three layers.