SiO2-Doped Sputtering Target Cristobalite Control
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Solution Overview
Problem
Sputtering targets for magnetic recording films, particularly those using SiO2-doped ferromagnetic alloys, face issues with micro-crack generation and extended 'burn-in time' due to crystallization of SiO2 into cristobalites, leading to particle formation during sputtering.
Innovation Solution
A sputtering target with a peak intensity ratio of crystallized SiO2 to background intensity of 1.40 or less, utilizing amorphous SiO2 and a thermal expansion coefficient change of 7% or less from 250°C to 350°C, and specific compositions like Co-Cr-Pt-SiO2, where Cr, Pt, and other elements are within certain mol percentages, to inhibit cristobalite formation and micro-crack generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If SiO2 is added to the sputtering target for magnetic recording film, then the alloy phase is magnetically separated, but cristobalites form during sputtering causing particle generation and extended burn-in time
Solution Approach 1:
The patent changes the physical and chemical parameters of SiO2 by controlling its particle size distribution (specifically keeping D50 between 0.5-5 μm and limiting fine particles below 0.5 μm to 5 wt% or less) and surface treatment. These parameter changes prevent cristobalite formation during sputtering while maintaining the magnetic separation function of SiO2 in the alloy phase.
Solution Approach 2:
The patent creates a composite sputtering target material consisting of ferromagnetic alloy powder and SiO2 powder with specific characteristics. The composite structure allows SiO2 to provide magnetic separation functionality while the controlled SiO2 properties prevent harmful cristobalite formation, resolving the contradiction between functional benefit and harmful effect.
2Stability of the object's composition
If SiO2 is added to the sputtering target, then the alloy phase is magnetically separated, but the burn-in time is extended
Solution Approach 1:
The patent changes the particle size parameters of SiO2 to optimize performance. By controlling D50 to 0.5-5 μm and limiting fine particles, the sputtering process achieves both magnetic separation functionality and reduced burn-in time, as the optimized particle size prevents cristobalite formation that would otherwise extend the burn-in period.
Solution Approach 2:
The patent applies local quality control by treating SiO2 particles differently based on size. Fine particles below 0.5 μm are strictly limited (≤5 wt%) while larger particles in the 0.5-5 μm range are encouraged (D50 within this range). This localized quality differentiation optimizes both magnetic separation and burn-in time characteristics.
3Stability of the object's composition
If conventional sputtering targets with SiO2 are used, then magnetic separation is achieved, but micro-cracks form in the target
Solution Approach 1:
The patent changes the particle size distribution parameters of SiO2 to prevent micro-crack formation. By controlling D50 to 0.5-5 μm and limiting fine particles below 0.5 μm to 5 wt% or less, the stress distribution during sputtering is optimized, preventing the formation of micro-cracks while maintaining magnetic separation functionality.
Solution Approach 2:
The patent develops a composite target material where SiO2 particles with specific size characteristics are integrated into the ferromagnetic alloy matrix. This composite structure provides magnetic separation while the controlled SiO2 particle properties prevent structural degradation through micro-crack formation, maintaining target strength and integrity.
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 significantly reduces particle generation and shortens the burn-in time, improving the quality and efficiency of magnetic recording film deposition by maintaining the magnetic characteristics and reducing defects.
Implementation Method 1
a sputtering target containing SiO2 for a magnetic recording film, wherein a peak intensity ratio of cristobalites, which are crystallized SiO2, to a background intensity is 1.40 or less
Implementation Method 2
a magnetron sputtering device comprising a DC power source... generate an electric field by applying high voltage between the substrate and the target under an inert gas atmosphere. Here, inert gas is ionized, plasma composed of electrons and positive ions is formed, the positive ions in the 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 containing SiO2 for a magnetic recording film, wherein a ratio of the peak intensity of cristobalites, which are crystallized SiO2, to the background intensity (cristobalite peak intensity/background intensity) in an X-ray diffraction is 1.40 or less. The present invention aims to obtain a sputtering target for a magnetic recording film capable of inhibiting the formation of cristobalites in the target which cause the generation of particles during sputtering, and shortening the burn-in time.