Arc Evaporation Source Magnetic Layout for Macroparticle Suppression
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Solution Overview
Problem
Conventional arc discharge film formation methods often result in surface roughness of the coating film due to the generation of macroparticles, as the arc spot tends to remain stationary on the target discharge surface, leading to adhesion of high-temperature film forming material droplets on the workpiece.
Innovation Solution
An arc evaporation source is designed with a cylindrical electromagnetic coil and a central magnet to create a repulsive magnetic field, actively moving the arc spot and suppressing macroparticle generation by stabilizing both horizontal and vertical magnetic fields on the target discharge surface, ensuring the film forming material is efficiently deposited on the workpiece.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a permanent magnet or electromagnet is arranged around the target with magnetic force lines perpendicular to the target discharge surface, then a strong vertical magnetic field is formed which directs charged particles toward the workpiece, but a horizontal magnetic field is hardly formed causing the arc spot to remain stationary and macroparticles to be generated
Solution Approach 1:
The magnetic field is segmented into two independent components: a vertical magnetic field generated by magnets arranged around the target discharge surface, and a horizontal magnetic field generated by an electromagnetic coil wound around the target. This segmentation allows each magnetic field component to perform its specific function independently - the vertical field directs particles toward the workpiece while the horizontal field moves the arc spot to prevent macroparticle generation.
Solution Approach 2:
Two magnetic field generation systems are merged into a single integrated target assembly: permanent magnets or electromagnets arranged radially around the target discharge surface, and an electromagnetic coil wound around the target body. The combined system produces both vertical and horizontal magnetic fields simultaneously, resolving the contradiction between particle direction control and arc spot movement.
2Device complexity
If the arc spot remains stationary on the target discharge surface, then the magnetic field configuration is simple, but macroparticles are generated which deteriorate the coating film surface roughness
Solution Approach 1:
The arc spot is transformed from a stationary position to a dynamic moving position through the application of a horizontal magnetic field generated by the electromagnetic coil. The coil current can be adjusted to control the strength of the horizontal magnetic field, thereby controlling the arc spot movement speed and range. This dynamic control prevents macroparticle generation while maintaining acceptable device complexity.
3Object-generated harmful factors
If the arc spot moves actively on the target discharge surface, then macroparticle generation is suppressed, but the magnetic field configuration becomes more complex requiring additional electromagnetic coils
Solution Approach 1:
The electromagnetic coil serves multiple functions simultaneously: it generates the horizontal magnetic field necessary for arc spot movement, provides magnetic confinement for the plasma, and can be used for magnetic heating of the target. This multi-functionality reduces the need for separate components and justifies the added complexity by delivering multiple benefits from a single added element.
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 configuration effectively reduces the number and size of macroparticles reaching the workpiece, improving the surface roughness of the coating film and maintaining stable arc discharge, while ensuring efficient film formation and productivity.
Implementation Method 1
The electromagnetic coil is a cylindrical electromagnetic coil arranged forward of the target discharge surface and having a center line orthogonal to the target discharge surface. The electromagnetic coil forms a first magnetic field.
Implementation Method 2
The central magnet is arranged on the center line rearward of the target discharge surface so as to form a second magnetic field. The central magnet forms the second magnetic field such that a component of the second magnetic force line parallel to the center line is in a reverse orientation to a component of the first magnetic force line parallel to the center line.
Implementation Method 3
an arc discharge voltage is applied between both electrodes. Then, each arc regulator forms a magnetic force line directed from the target to a workpiece (vapor deposition object, film forming target), whereby charged particles of the vapor deposition substance emitted from a target discharge surface upon receiving the arc discharge
Data Source
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AI summary
An arc evaporation source includes a target including a target discharge surface, an arc power supply, an electromagnetic coil arranged forward of the target, and a central magnet arranged rearward of the target. The electromagnetic coil forms a first magnetic field containing a first magnetic force line intersecting the target discharge surface and extending so as to pass through, in a front-rear direction, radially inside the electromagnetic coil. The central magnet forms a second magnetic field containing a second magnetic force line extending in a front-rear direction in a region between the central magnet and the target discharge surface. Repulsion between the first magnetic field and the second magnetic field stably forms a horizontal magnetic field and a vertical magnetic field on the target discharge surface.