Single Beam Ion Source Cusp Magnetic Field Design
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Solution Overview
Problem
Conventional ion sources, such as racetrack designs, face challenges including high ion energies that can damage films, wide distribution of emission angles affecting surface morphology, and frequent maintenance due to contamination and alignment issues.
Innovation Solution
A single beam plasma or ion source apparatus that emits a single ion beam with a modifiable diameter, operates over a wide range of pressures and gases, and can adjust ion energies, featuring a design without a filament and with a non-magnetic cap for easy maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If racetrack ion source design is used, then ion extraction is achieved, but ion energies are too high causing film damage
Solution Approach 1:
The patent changes the electromagnetic field parameters by using permanent magnets arranged in a specific pattern to create a cusp magnetic field configuration. This modifies the electron drift trajectory and reduces the voltage required for ion extraction, thereby lowering ion energy from >250V to controllable levels that prevent film damage while maintaining effective ion beam generation
2Ease of operation
If racetrack ion source design is used, then ion extraction is achieved, but emission angles are wide affecting surface morphology
Solution Approach 1:
The patent creates a focused ion beam with narrow angular distribution by designing the magnetic pole arrangement to confine electron drift paths. The cusp magnetic field configuration locally concentrates the ion emission in a specific direction, producing a well-collimated beam that improves surface morphology control while maintaining effective ion extraction
3Measurement precision
If narrow emission slit is used in racetrack ion source, then ion beam focus is improved, but maintenance frequency increases due to contamination
Solution Approach 1:
The patent eliminates the narrow emission slit design by using a different magnetic field configuration that naturally focuses the ion beam through the cusp field geometry. This removes the component prone to contamination and material deposition, thereby reducing maintenance frequency while preserving ion beam focus through the magnetic field shaping rather than physical aperture constraints
4Reliability
If racetrack ion source is used, then plasma discharge is sustained, but voltage requirement is high (>250V)
Solution Approach 1:
The patent changes the electromagnetic field configuration from conventional racetrack geometry to a cusp magnetic field arrangement using permanently magnetized poles. This parameter change in field topology improves plasma confinement efficiency and reduces the voltage threshold for sustaining plasma discharge, enabling reliable operation at lower voltages below 250V
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 apparatus achieves stable, high-quality thin film deposition with improved ion-surface interactions, reduced contamination, and lower maintenance requirements, leading to dense, smooth films with enhanced properties.
Implementation Method 1
The magnetic poles are connected to a ground potential and act as cathodes 5. Electrons attracted toward the anode experience a Lorenz force that drives the electrons in E×B direction
Implementation Method 2
Electrons attracted toward the anode experience a Lorenz force that drives the electrons in E×B direction (where E is an electrical field vector and B is a magnetic induction field vector)
Implementation Method 3
the gap between the anode and cathode must be small (a few millimeters) to create a strong electrical field to extract the ions
Data Source
Figure 1~3
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Figure 6~8
AI summary
A single beam plasma or ion source apparatus (21, 221, 321, 421, 521) is provided. Another aspect employs an ion source (25) including multiple magnets (91) and magnetic shunts (93) arranged in a generally E cross-sectional shape. A further aspect of an ion source includes magnets and/or magnetic shunts which create a magnetic flux (115) with a central dip (117) or outward undulation located in an open space within a plasma source. In another aspect, an ion source includes a removeable cap (73, 573) attached to an anode body (97) which surrounds the magnets. Yet a further aspect provides a single beam plasma source (221, 521) which generates ions simultaneously with target sputtering and at the same internal pressure.