CoPt Sputtering Target Grain Control
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Solution Overview
Problem
Current magnetic recording media face challenges in micronizing magnetic crystal grains while maintaining good magnetic properties, as the micronization of CoPt-based alloy crystal grains leads to thermal fluctuation phenomena and reduced thermal stability, and existing methods struggle to reduce the distance between crystal grains effectively.
Innovation Solution
A sputtering target comprising metallic Co, Pt, and an oxide, with a balance of B2O3 and high-melting-point oxides, is used to create a magnetic thin film with micronized crystal grains and reduced inter-grain distance, where B2O3 with a low melting point and high-melting-point oxides like TiO2 facilitate columnar growth and grain separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the CoPt-based alloy crystal grains are micronized to increase recording density, then the signal-to-noise ratio is improved, but thermal fluctuation phenomenon occurs and thermal stability is impaired
Solution Approach 1:
The patent changes the chemical composition parameters of the sputtering target, specifically setting Co content to 70-90 at% and Pt content to 10-30 at%, which optimizes the magnetic properties and magnetocrystalline anisotropy of the resulting thin film, thereby improving thermal stability while maintaining fine grain structure
Solution Approach 2:
The patent creates a composite material system by incorporating oxide components (26-40 vol%) into the CoPt-based alloy, forming a granular structure where magnetic CoPt alloy grains are dispersed in a non-magnetic oxide matrix, which suppresses thermal fluctuation and enhances thermal stability
2Manufacturing precision
If the distance between crystal grain centers is reduced to maintain signal intensity, then recording density is improved, but grain interaction increases and coercive force is reduced
Solution Approach 1:
The patent introduces oxide components as intermediary materials that form grain boundary phases between CoPt alloy grains. These oxide grain boundaries act as magnetic isolation barriers, preventing unwanted magnetic interaction between adjacent grains even when grains are closely spaced, thereby maintaining high coercive force while achieving high recording density
3Manufacturing precision
If the oxide addition amount is increased to micronize magnetic crystal grains, then crystal grain size is reduced, but the width of crystal grain boundary increases and distance between grain centers cannot be reduced
Solution Approach 1:
The patent optimizes the oxide content parameter within the specific range of 26-40 vol%, balancing the competing requirements: sufficient oxide is present to form grain boundaries and suppress grain growth, but not so much that grain boundaries become excessively wide and increase the distance between grain centers
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 approach results in a magnetic thin film with micronized crystal grains and reduced inter-grain distance, enhancing magnetic properties such as magnetocrystalline anisotropy and thermal stability, thereby improving recording density and signal intensity.
Implementation Method 1
a sputtering target for magnetic recording media, and in particular, to a sputtering target that contains metallic Co, metallic Pt, and an oxide
Implementation Method 2
In addition, in order to grow the CoPt-based alloy crystal grains having large Ku in a columnar shape, phase separation between the CoPt-based alloy crystal grains and grain boundary material must be achieved
Data Source
AI summary
A sputtering target for magnetic recording media capable of producing a magnetic thin film in which the magnetic crystal grains are micronized and the distance between the centers of the grains is reduced while good magnetic properties are maintained. The target including metallic Pt and an oxide, with the balance being metallic Co and inevitable impurities, wherein the Co is contained in a range of 70 at % to 90 at % and the Pt is contained in a range of 10 at % to 30 at % relative to a total of metallic components in the sputtering target for magnetic recording media, the oxide is contained in a range of 26 vol % to 40 vol % relative to a total volume of the sputtering target for magnetic recording media, and the oxide is composed of B2O3 and one or more high-melting-point oxides having a melting point of 1470° C. or higher and 2800° C. or lower.