Movable Magnet Array for Uniform Cylindrical Target Erosion
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Solution Overview
Problem
Cylindrical targets in magnetron sputtering systems experience uneven material erosion, leading to inefficient target utilization and frequent replacements, as existing solutions fail to uniformly distribute sputter rates across the target surface regardless of material type, thickness, or permeability.
Innovation Solution
A magnetron apparatus with an elongated magnet array and a drive mechanism, featuring axially movable shunts that adjust the magnetic field distribution along the target, ensuring uniform sputter rates by varying the gap width between magnet segments, thereby reducing net target erosion and improving material utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a stationary magnet is used in a rotating cylindrical target, then the magnetic field is stable and easy to control, but the target experiences uneven erosion with severe wear at the ends and less wear at the center
Solution Approach 1:
The magnet array is designed with movable portions that can shift axially relative to the rotating target. This dynamic configuration allows the magnetic field distribution to change during operation, enabling the sputter rate to be averaged across the target length and achieving more uniform target erosion patterns.
Solution Approach 2:
The magnet array is divided into stationary and movable portions, with the movable portions positioned at the ends of the racetrack. This segmentation allows independent control of magnetic field distribution at different locations, enabling compensation for the non-uniform erosion pattern that occurs with stationary magnets.
2Productivity
If the sputter process is stopped when target ends are eroded, then the target material utilization is limited, but continuing operation causes premature end erosion
Solution Approach 1:
By making portions of the magnet array movable, the system can dynamically adjust the magnetic field distribution to maintain uniform sputter rates across the entire target length. This allows continuous operation without premature target replacement, significantly improving target material utilization and reducing waste.
3Loss of substance
If sophisticated magnetic field manipulation is used to match erosion rates, then target utilization improves for some materials, but the solution becomes strongly dependent on material thickness and permeability requiring unique solutions for each material type
Solution Approach 1:
The movable magnet portions provide a universal dynamic adjustment mechanism that can adapt to different material types, thicknesses, and permeabilities through controlled motion rather than material-specific magnetic field configurations. This approach achieves erosion uniformity across various materials without requiring unique solutions for each material type.
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 improved cylindrical sputter target utilization and increased magnetic field strength without sacrificing target material efficiency, enhancing thin film properties by uniformly distributing the sputter rate across the target surface.
Implementation Method 1
The magnet produces a magnetic field adjacent to the target. This magnetic field confines the plasma to the outer surface of the target.
Implementation Method 2
This magnetic field confines the plasma to the outer surface of the target
Implementation Method 3
magnetron sputtering or reactive sputtering of materials from a cathode target onto a substrate
Data Source
AI summary
An apparatus for sputtering target material onto a substrate based on a plasma confining racetrack having two parallel straight portions and two turnaround portions includes a tubular target, an elongated magnet array, and a drive mechanism. The tubular target has two ends in proximity to the two turnaround portions and a longitudinal axis about which the target is rotatable. The magnet array is supported within the target to generate a plasma-confining magnetic field. The array includes a central stationary portion of magnets and two axially movable shunts positioned at the ends of the stationary portion. Each shunt carries a magnet segment configured to slidably extend from each end of the stationary portion to define a gap. The gaps are positioned internal to the turnaround portions. The drive mechanism axially moves the shunts parallel to the longitudinal axis of the target to vary a width of the gaps.