Ring Cathode Magnetron Sputtering for Uniform Coating
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Solution Overview
Problem
Magnetron sputtering systems face challenges in achieving uniform coating thickness and high deposition rates across large substrates without using masks, while maintaining low defect levels and avoiding material waste and arcing issues.
Innovation Solution
A magnetron sputtering device with a ring-shaped cathode and a low-voltage anode vessel, where the anode is positioned at the center of the cathode ring, and an activated reactive gas source is integrated to enhance coating uniformity and efficiency, allowing for increased coating area and target material utilization without masking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If heavy masking is used to achieve acceptable thickness distribution, then coating uniformity is improved, but material utilization is reduced and device complexity increases
Solution Approach 1:
The cathode is segmented into multiple independent magnetron modules arranged in an array, allowing each module to be optimized for specific coating zones. This segmentation enables precise control of material flux distribution without requiring masks to block excess material, thereby improving material utilization while maintaining thickness uniformity.
Solution Approach 2:
The patent transitions from a single planar cathode to a three-dimensional array of magnetron modules with varying positions and orientations. By utilizing vertical and horizontal positioning dimensions, the system achieves uniform coating distribution across the substrate without needing masks to block material in specific areas.
2Manufacturing precision
If masks are used to control coating distribution, then thickness uniformity is improved, but device complexity and maintenance requirements increase
Solution Approach 1:
The masking function is extracted and replaced by the geometric arrangement and magnetic field configuration of the magnetron module array. Instead of adding masks to control coating distribution, the system uses the inherent directional control of each magnetron module to deposit material only where needed, eliminating the masking subsystem entirely.
Solution Approach 2:
The magnetron module array is designed to self-regulate coating distribution through its geometric configuration and magnetic field patterns. Each module's plasma confinement and material ejection are inherently directional, allowing the system to achieve uniform coating without external masking components that would require maintenance.
3Manufacturing precision
If masks are used to reduce coating rate variation, then thickness uniformity is improved, but productivity is reduced due to material shielding
Solution Approach 1:
Each magnetron module in the array is configured with specific local characteristics including varying distances from the substrate, different magnetic field strengths, and adjusted power levels. This local optimization allows each module to contribute appropriately to the overall coating uniformity without requiring masks to reduce material flux in certain areas, thereby maintaining high deposition rates.
4Reliability
If high pressure is used to sustain plasma, then plasma stability is improved, but coating quality deteriorates due to gas scatter
Solution Approach 1:
The array of magnetron modules creates continuous localized plasma regions that maintain stability through cumulative effect. Each module sustains its own plasma discharge, and the combined output provides continuous material flux to the substrate. This allows operation at lower pressures where the mean free path is longer, reducing gas scatter while maintaining plasma stability through the distributed modular architecture.
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 solution achieves excellent coating uniformity across large substrates with reduced defect levels and increased throughput, maintaining high coating quality and efficiency, and allows for the coating of larger substrates like 300mm without sacrificing quality, while minimizing material waste and arcing.
Implementation Method 1
a magnetic field confines the glow discharge plasma and increases the path length of the electrons moving under the influence of the electric field
Implementation Method 2
a DC voltage applied between the cathode and the anode ionizes the argon into a plasma
Implementation Method 3
The ions strike the target in front of the cathode with a substantial energy and cause target atoms or atomic clusters to be sputtered from the target
Implementation Method 4
The ions are accelerated into the target of coating material at the cathode by an electric field causing atoms of the target material to be ejected from the target surface
Data Source
Figure 1
Figure 2A~2C
Figure 3A
AI summary
The present invention relates to a magnetron sputtering device including a large ring cathode (12) having a defined inner radius (r1). The position of the ring cathode is offset in relation to a center point (C) of a planetary drive system. An anode or reactive gas source may be located within the inner radius of the ring cathode. Lower defect rates are obtained through the lower power density at the cathode which suppresses arcing, while runoff is minimized by the cathode to planet geometry without the use of a mask.