Rotatable Magnetron Sputtering Electrode Fine Tuning
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Solution Overview
Problem
Rotatable cylindrical magnetron sputtering devices face issues with target material underutilization, non-uniform film thickness, and high power delivery complexity, including overheating and eddy currents, which affect deposition rate and coating uniformity.
Innovation Solution
A retrofit magnet arrangement with profiled magnets and a drive assembly using common components to improve target utilization and deposition rate, along with a shunting mechanism for fine-tuning the magnetic field to achieve uniform coating, reducing material waste and complexity in high power AC current delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If stationary profiled magnets are used to control magnetic field shape, then target material utilization is improved, but device complexity increases
Solution Approach 1:
The patent converts the static magnet arrangement into a dynamic system by making the magnets rotatable along with the cylindrical target. This dynamic configuration maintains optimal magnetic field shaping throughout the rotation cycle, improving target utilization without requiring complex stationary magnet structures. The magnets are attached to the cathode body and rotate synchronously with the target, creating a continuously optimized sputtering environment.
Solution Approach 2:
The invention transitions from a planar magnet arrangement to a three-dimensional cylindrical configuration. The profiled magnets are arranged in multiple axial positions on the cathode body, creating a volumetric magnetic field structure that better matches the cylindrical target geometry. This dimensional expansion enables improved magnetic flux distribution and target surface utilization.
2Productivity
If high power AC current is delivered to the rotating target, then deposition rate is improved, but harmful effects such as overheating and eddy currents increase
Solution Approach 1:
The patent replaces the conventional mechanical brush assembly current delivery system with an inductive coupling system. Electrical current is transferred to the rotating target through electromagnetic induction between stationary and rotating magnetic fields, eliminating the need for sliding contacts. This substitution eliminates brush overheating and erosion problems while enabling high power delivery for high deposition rates.
Solution Approach 2:
The invention introduces magnetic coupling as an intermediary mechanism for power transfer. The magnetic field serves as the mediator between the stationary power source and the rotating target, enabling non-contact energy transmission. This intermediary approach avoids direct electrical contact, eliminating the harmful effects associated with brush assemblies while maintaining efficient power delivery.
3Power
If custom brush assemblies with high silver content are used to carry current, then current carrying capacity is improved, but cost and brittleness increase
Solution Approach 1:
The patent eliminates the mechanical brush assembly system entirely and replaces it with an inductive power transfer system. Current is delivered to the rotating target through electromagnetic coupling rather than physical contact. This substitution removes the need for expensive, brittle high-silver-content brush materials, significantly reducing manufacturing costs while eliminating the inherent brittleness and short operating life issues.
4Reliability
If custom designed ceramic bearing is used to address eddy current heating, then reliability is improved, but cost and replaceability worsen
Solution Approach 1:
The patent replaces the mechanical bearing system with a magnetic levitation system. The rotating target is suspended and supported by magnetic fields rather than physical contact bearings. This substitution eliminates eddy current heating in the bearing, removes the need for expensive custom ceramic bearings, and enables easy replacement or adjustment of the rotating assembly without dealing with fragile, difficult-to-replace ceramic components.
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
Enhances target material utilization, reduces material waste on chamber walls, and achieves more uniform coatings by optimizing the magnetic field, while simplifying the drive assembly and reducing costs associated with custom components.
Implementation Method 1
Electrical power supplied to the electrode produces an electronic discharge which ionizes the process gas and produces charged gaseous ions from the atoms of the process gas. The ions are accelerated and retained within a magnetic field formed over the target
Implementation Method 2
The shunts are located between the first turnaround and the second turnaround and arranged at a plurality of different locations with respect to the length direction of the magnet arrangement. Shunts at different length locations are individually movable relative to the magnet arrangement in at least the height direction, thereby allowing for tuning of the effect of the magnet arrangement on coating thickness uniformity
Implementation Method 3
The ions are accelerated and retained within a magnetic field formed over the target, and are propelled toward the surface of the target which is composed of the material sought to be deposited on a substrate. Upon striking the target, the ions dislodge target atoms from the target which are then deposited upon the substrate
Data Source
AI summary
A magnetron sputtering electrode for use in a rotatable cylindrical magnetron sputtering device, the electrode including a cathode body defining a magnet receiving chamber and a cylindrical target surrounding the cathode body. The target is rotatable about the cathode body. A magnet arrangement is received within the magnet receiving chamber, the magnet arrangement including a plurality of magnets. A shunt is secured to the cathode body and proximate to a side of the magnet arrangement, the shunt extending in a plane substantially parallel to the side of the magnet arrangement. A method of fine-tuning a magnetron sputtering electrode in a rotatable cylindrical magnetron sputtering device is also disclosed.