Perpendicular Magnetic Layer Sputtering for Thermal Stability
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Solution Overview
Problem
Current methods for manufacturing magnetic recording media with high recording density struggle to achieve both improved recording and reproducing characteristics and thermal fluctuation resistance without compromising film density and hardness, particularly when forming magnetic layers with granular structures at low sputtering gas pressures.
Innovation Solution
A method involving the formation of a perpendicular magnetic layer with a granular structure using a target containing an oxide of Co and a nonmagnetic metal, where the oxygen proportion is higher than in the layer, and sputtering is conducted at a pressure of 1 Pa or less, allowing for controlled film formation and enhanced magnetic separation and hardness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a magnetic layer with granular structure is formed at low sputtering gas pressure to improve recording and reproducing characteristics, then thermal fluctuation resistance is enhanced, but film density and hardness deteriorate
Solution Approach 1:
The patent changes the sputtering gas pressure parameter to 1 Pa or less to form a granular magnetic layer structure that improves thermal fluctuation resistance while maintaining film density and hardness through controlled deposition conditions
Solution Approach 2:
The patent uses a composite target material containing Co oxide and Co nonmagnetic metal compound with specific oxygen proportion (1.2-4 times higher than the magnetic layer) to simultaneously achieve granular structure formation and maintain film quality at low pressure
2Reliability
If oxygen proportion in the target is increased to stabilize oxygen concentration in the magnetic layer, then recording and reproducing characteristics are improved, but target composition control becomes more difficult
Solution Approach 1:
The patent establishes a specific parameter range for oxygen proportion in the target (1.2-4 times higher than in the magnetic layer) that simultaneously achieves stable oxygen concentration in the film and manageable target composition control
Solution Approach 2:
The patent uses the oxygen proportion in the target as a feedback parameter to control and stabilize the oxygen concentration in the formed magnetic layer, ensuring consistent granular structure and magnetic properties
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 results in a magnetic recording medium with excellent recording and reproducing characteristics, thermal fluctuation resistance, and high recording density, while maintaining film density and hardness, by stabilizing oxygen concentration and increasing magnetic flux control.
Implementation Method 1
forming a perpendicular magnetic layer by a sputtering process
Data Source
AI summary
There are provided a method for manufacturing a magnetic recording medium which is excellent in terms of both the recording and reproduction characteristics and the thermal fluctuation characteristics without reducing the density and hardness of the perpendicular magnetic layer; a magnetic recording medium; and a magnetic recording and reproducing apparatus with which an excellent recording density is achieved,wherein, in the method for manufacturing the magnetic recording medium,at least a portion of the perpendicular magnetic layer 4 is formed as a magnetic layer having a granular structure that contains Co as a major component and also contains an oxide of at least one nonmagnetic metal selected from the group consisting of Cr, Si, Ta, Al, Ti, W and Mg;a target for forming the perpendicular magnetic layer 4 by the sputtering process is prepared so as to include an oxide of Co and a compound of Co and at least one nonmagnetic metal selected from the group consisting of Cr, Si, Ta, Al, Ti, W and Mg, and to make the proportion of oxygen contained in the target higher than the proportion of oxygen contained in the perpendicular magnetic layer 4; anda sputtering gas pressure at the time of forming the perpendicular magnetic layer is set to 1 Pa or less.