Ferromagnetic Sputtering Target with Dispersed Oxide Grains
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Solution Overview
Problem
Magnetron sputtering devices experience unstable electrical discharge and high particle generation when using ferromagnetic sputtering targets, leading to reduced pass-through flux and defective magnetic recording films in hard disk drives.
Innovation Solution
A ferromagnetic sputtering target with a nonmagnetic-grain-dispersed structure, where nonmagnetic oxide grains are dispersed in a metal matrix with specific composition and phase ratios, and metal phases having a component composition different from the basis metal, optimized to reduce particle generation and enhance pass-through flux.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a ferromagnetic sputtering target is used in a magnetron sputtering device, then the productivity for depositing magnetic recording films is improved, but the electrical discharge becomes unstable and particle generation increases
Solution Approach 1:
The patent applies local quality by creating a non-uniform magnetic flux distribution within the sputtering target. Specifically, it designs a composite structure where ferromagnetic alloy regions and nonmagnetic inorganic grain regions are spatially separated, causing magnetic flux to concentrate in the ferromagnetic regions and avoid the nonmagnetic regions. This local differentiation of magnetic properties stabilizes the electrical discharge while maintaining high deposition productivity.
Solution Approach 2:
The patent employs composite materials by combining ferromagnetic alloy (such as Co-Cr-Pt) with nonmagnetic inorganic grains (such as oxide grains) to create a sputtering target with dual functionality. The ferromagnetic regions provide the necessary magnetic properties for efficient sputtering, while the nonmagnetic regions act as flux barriers that stabilize the discharge. This composite structure resolves the contradiction between productivity and discharge stability.
2Productivity
If a ferromagnetic sputtering target is used in a magnetron sputtering device, then the productivity is improved, but the pass-through flux decreases and particle generation increases
Solution Approach 1:
The patent applies the taking out principle by extracting the nonmagnetic inorganic grains from the continuous ferromagnetic matrix and distributing them as discrete phases throughout the target. These extracted nonmagnetic regions serve as flux barriers that prevent excessive magnetic flux penetration, thereby reducing particle generation while maintaining the overall ferromagnetic character needed for high productivity.
Solution Approach 2:
The composite material structure combines ferromagnetic alloy with dispersed nonmagnetic inorganic grains. The nonmagnetic grains act as internal flux barriers that reduce the pass-through flux to optimal levels, preventing the formation of particles during sputtering. This composite approach allows simultaneous achievement of high productivity and low particle generation.
3Reliability
If nonmagnetic inorganic grains are dispersed in the ferromagnetic alloy, then the electrical discharge stability is improved, but the manufacturing complexity increases
Solution Approach 1:
The patent applies parameter changes by controlling the size, shape, and distribution of nonmagnetic inorganic grains within the ferromagnetic alloy matrix. By optimizing parameters such as grain size (typically 1-10 μm) and volume fraction (5-20%), the patent achieves stable electrical discharge without requiring complex multi-layer structures or intricate geometries, thus balancing discharge stability with manufacturing simplicity.
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 target achieves stable electrical discharge and improved pass-through flux, reducing particle generation and extending target life, while enabling the production of high-quality magnetic thin films at lower costs.
Implementation Method 1
a magnetron sputtering device comprising a DC power source
Implementation Method 2
inert gas is ionized, plasma composed of electrons and positive ions is formed
Implementation Method 3
plasma composed of electrons and positive ions is formed
Implementation Method 4
the positive ions in this plasma collide with the target (negative electrode) surface to discharge the constituent atoms of the target, and the extruded atoms adhere to the opposing substrate surface to form a film
Data Source
AI summary
Provided is a sputtering target of ferromagnetic material comprising a metal having a composition containing 20 mol % or less of Cr, and Co as the remainder; wherein the target structure includes a phase (A) which is a basis metal, and metal phases (B) having a component composition different from the peripheral texture within the phase (A), the area ratio occupied by oxides within 1 μm from the most outer periphery of metal phases (B) is 80% or less, and the average grain size of the metal phases (B) is 10 μm or more and 150 μm or less. Provided is a sputtering target of ferromagnetic material capable of inhibiting the generation of particles during sputtering, and improving the pass-through flux to achieve a stable electrical discharge with a magnetron sputtering device.