Magnet Assembly for High Power Pulsed Magnetron Sputtering
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Solution Overview
Problem
Conventional magnet assemblies for high power pulsed magnetron sputtering exhibit lower deposition rates compared to DC magnetron sputtering due to the 'return effect' of metal ions, magnetic confinement, and sideways movement of sputtered ions, which limits the escape of ions from the plasma region.
Innovation Solution
A magnet assembly with a specific magnetic field topology comprising tangential and total magnetic field distributions, featuring outer and inner continuous rings with alternating high and low field values and gradients, designed to balance electron trapping and sputtered ion leakage, allowing for higher ion flux and reduced arcing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional magnet assemblies are used for high power pulsed magnetron sputtering, then magnetic confinement is achieved, but deposition rates are lower due to ion return effect and limited ion escape from plasma region
Solution Approach 1:
The magnet assembly is segmented into multiple magnet elements (first, second, third, and fourth magnet elements) arranged in a specific pattern around the target. This segmentation creates distinct magnetic field regions that allow controlled electron trapping while providing pathways for ion escape, thereby increasing deposition rate without compromising plasma stability.
Solution Approach 2:
Different regions of the magnet assembly have different magnetic field strengths and configurations. The magnet elements are positioned to create localized magnetic field zones that optimize electron confinement in certain areas while allowing ion escape in other areas, achieving both high deposition rate and stable plasma maintenance.
2Productivity
If high peak power pulses are applied to generate high electron densities, then ionization of sputtered material is enhanced, but arcing may increase
Solution Approach 1:
The magnet assembly is designed to work dynamically with pulsed power application, where the magnetic field configuration optimizes electron trapping during high peak power pulses to enhance ionization efficiency. The segmented magnet structure allows the plasma to be confined during pulsing while providing escape paths that prevent excessive charge buildup and reduce arcing.
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 magnet assembly achieves deposition rates up to twice those of conventional systems and significantly reduces arcing, enabling more efficient and stable high power pulsed magnetron sputtering with improved film quality and uniformity.
Implementation Method 1
A magnet assembly for use in high power pulsed magnetron sputtering comprises a configuration of magnets having a magnetic field topology comprising magnetic field components Bx, By and Bz
Implementation Method 2
the tangential magnetic field B// alternates between (a) high field values greater than 200 G and high gradients in the z-direction of at least 1000 G/in, and (b) low field values of less than 50 G and low gradients in the z-direction of at most 250 G/in
Implementation Method 3
A gas such as argon (the 'working gas') is ionized between the cathode (target) and the anode, forming a plasma containing positive argon ions and free electrons
Implementation Method 4
The magnetic field causes electrons in the plasma to follow curved trajectories. A longer (curved) path increases the probability of collision with gas atoms in the chamber
Implementation Method 5
The negatively charged target attracts the positive ions from the plasma. The positive ions are accelerated to a high kinetic energy and strike the surface of the target structure
Implementation Method 6
an ionization zone is created between the pulsed plasma and the workpiece away from the front surface of the sputtering target, the ionization zone having a sufficient electron density and temperature to ionize an additional fraction of the atoms removed from the sputtering target
Data Source
AI summary
A magnet assembly for use in high power pulsed magnetron sputtering comprises a configuration of magnets having a magnetic field topology comprising magnetic field components Bx, By and Bz. A tangential magnetic field B// distribution on an x-y plane above the configuration of magnets comprising an outer continuous ring and one or more inner continuous rings contained in the outer continuous ring. A total magnetic field Btot distribution on an x-z plane intersecting the configuration of magnets comprises an outer closed loop and one or more inner closed loops contained in the outer closed loop, where, as a function of x, a tangential magnetic field B// alternates between (a) high field values greater than 200 G and high gradients in the z-direction of at least 1000 G/in, and (b) low field values of less than 50 G and low gradients in the z-direction of at most 250 G/in.