Two-Level Folded Magnetron for Uniform Sputtering
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Solution Overview
Problem
Large flat panel sputtering processes face issues with incomplete target utilization due to uneven sputtering rates, where edge portions of the target are eroded more quickly than interior portions, leading to inefficiencies in magnetron design for scanning over large areas.
Innovation Solution
A magnetron design featuring an outer magnetic pole surrounding an inner pole with a closed loop plasma track, allowing for scanning in both perpendicular and parallel directions, and reinforced magnets at corners to maintain even magnetic field distribution, reducing hot spots and enhancing target utilization by using a two-level folded serpentine magnetron configuration with tailored magnetic field adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a conventional magnetron is used for large flat panel sputtering, then the sputtering process can be performed, but the target utilization is incomplete due to uneven sputtering rates with edges eroded more quickly than interior portions
Solution Approach 1:
The magnetron is divided into multiple discrete magnet elements arranged in alternating polarity patterns. This segmentation allows independent control and optimization of magnetic field distribution across different regions of the target, enabling uniform sputtering rates across the entire large-area target surface while improving target utilization.
Solution Approach 2:
The patent applies different magnetic field strengths and configurations to different regions of the magnetron. Specifically, edge regions are provided with enhanced magnetic field intensity compared to interior regions, compensating for the naturally higher erosion rates at edges and achieving uniform overall sputtering across the target surface.
2Area of stationary object
If the magnetron scans over large target areas, then coverage is improved, but maintaining even magnetic field distribution becomes difficult leading to hot spots
Solution Approach 1:
The magnetron incorporates movable scanning mechanisms that dynamically adjust the position and orientation of the magnet elements relative to the target surface. This dynamic capability allows the magnetic field distribution to be optimized for different regions during the scanning process, maintaining field uniformity across large areas while preventing hot spot formation through continuous repositioning.
Solution Approach 2:
The patent extends the magnetron design into three dimensions by incorporating vertical stacking of magnet elements and three-dimensional scanning trajectories. This multi-dimensional approach allows coverage of large target areas while maintaining consistent magnetic field intensity through spatial distribution of magnetic sources and optimized scanning paths.
3Productivity
If magnetic field intensity is increased to improve sputtering rate, then productivity increases, but hot spots are created leading to non-uniform erosion
Solution Approach 1:
The patent implements spatially varying magnetic field intensities by arranging magnets with alternating polarities and different strengths in specific patterns. Regions prone to hot spots receive reduced field intensity, while areas with lower natural sputtering rates receive enhanced fields, achieving high overall productivity with uniform erosion across the target surface.
Solution Approach 2:
The alternating polarity magnet arrangement creates continuous plasma discharge paths across the target surface, ensuring uniform energy distribution and preventing localized hot spots. The continuous scanning motion further ensures that all regions receive equivalent cumulative exposure, maintaining uniform erosion while sustaining high sputtering rates throughout the process.
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 design achieves more uniform sputtering and complete target utilization by minimizing hot spots and maintaining consistent magnetic field intensity across the target, improving the efficiency of large-area sputtering processes.
Implementation Method 1
If it has an inner magnetic pole 26 of one vertical magnetic polarity surrounded by an outer magnetic pole 28 of the opposite polarity to project a magnetic field within the chamber 18
Implementation Method 2
The magnetic field from the magnetron 24 traps electrons and thereby increases the density of the plasma
Implementation Method 3
A magnetron design featuring an outer magnetic pole surrounding an inner pole with a closed loop plasma track, allowing for scanning in both perpendicular and parallel directions
Implementation Method 4
The positive argon ions are attracted to the target assembly 16 and sputter metal atoms from the target layer. The metal atoms are partially directed to the panel 14 and deposit thereon a layer
Implementation Method 5
under the proper chamber conditions a high-density plasma loop is formed in the processing space adjacent the target layer. The two opposed magnetic poles 26, 28 are separated by a substantially constant gap defining the track of the plasma loop
Data Source
AI summary
A magnetron assembly including one or more magnetrons each forming a closed plasma loop on the sputtering face of the target. The target may include multiple strip targets on which respective strip magnetrons roll and are partially supported on a common support plate through a spring mechanism. The strip magnetron may be a two-level folded magnetron in which each magnetron forms a folded plasma loop extending between lateral sides of the strip target and its ends meet in the middle of the target. The magnets forming the magnetron may be arranged in a pattern having generally uniform straight portions joined by curved portion in which extra magnet positions are available near the corners to steer the plasma track. Multiple magnetrons, possibly flexible, may be resiliently supported on a scanned support plate and individually partially supported by rollers on the back of one or more targets.