Beam Extraction Slit Structure for Ion Source Meniscus Control
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Solution Overview
Problem
The existing ion implanter technologies face challenges in maintaining a stable plasma meniscus, which affects the efficiency of ion beam extraction and productivity due to variations in plasma density and electric field intensity, leading to poor beam properties and reduced ion implantation current.
Innovation Solution
A beam extraction slit structure with a plasma meniscus fixing part at the center and a non-fixing part at the ends, designed to maintain the plasma meniscus at optimal positions within the slit, utilizing a thermionic emission unit and magnetic field to stabilize the plasma and enhance ion beam extraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the plasma density is increased to improve ion beam current, then the ion implantation productivity is improved, but the plasma meniscus position becomes unstable and beam properties deteriorate
Solution Approach 1:
The invention applies different surface properties to different regions of the extraction electrode. The central region has a plasma meniscus fixing part with specific surface characteristics that stabilize the plasma meniscus position, while the end regions have different surface properties that allow controlled movement. This local differentiation resolves the contradiction by maintaining stability where needed (center) while allowing adaptability where required (ends), enabling high plasma density operation without meniscus instability.
2Productivity
If the electric field intensity is increased to improve beam extraction efficiency, then the ion beam current is improved, but the plasma meniscus shape becomes unstable and beam properties vary
Solution Approach 1:
The extraction electrode is designed with spatially varying surface properties: the central fixing part provides strong electric field anchoring for plasma meniscus stabilization, while the end non-fixing parts have modified surface characteristics that accommodate meniscus movement. This local quality differentiation allows high electric field intensity to be applied without causing overall meniscus shape instability, maintaining consistent beam properties during efficient extraction.
3Ease of manufacture
If a uniform slit structure is used to simplify the device design, then the manufacturing complexity is reduced, but the plasma meniscus cannot be stabilized across varying plasma densities
Solution Approach 1:
Rather than using a completely uniform slit structure, the invention introduces localized surface modifications only at critical regions (central fixing part and end non-fixing parts) of the extraction electrode. This approach maintains manufacturing simplicity compared to complex adjustable mechanisms while providing the functional differentiation needed to stabilize plasma meniscus across varying plasma densities, ensuring consistent beam extraction performance.
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 stabilizes the plasma meniscus, improves ion beam extraction efficiency, and maintains high productivity by optimizing beam properties across varying plasma densities, ensuring consistent ion implantation current.
Implementation Method 1
An indirectly heated cathode ion source is configured to heat a filament by a direct current so as to generate thermoelectrons, which heat the cathode
Implementation Method 2
a magnetic field generator that applies a magnetic field aligned with the longitudinal direction of the slit in the arc chamber
Implementation Method 3
The electric field produced at the beam extraction slit of the arc chamber in accordance with the voltage applied across the extraction electrode and the beam extraction slit extracts a beam from the ion source
Implementation Method 4
The thermoelectrons generated from the heated cathode are accelerated in an arc chamber and collide with source gas molecules in the arc chamber, thereby ionizing atoms included in the source gas molecules
Data Source
AI summary
A beam extraction slit structure includes a plasma chamber interior surface that is, in operation, in contact with a plasma; a plasma chamber exterior surface that faces an extraction electrode; and a slit surface part that forms a beam extraction slit between the plasma chamber interior surface and the plasma chamber exterior surface in the beam extraction direction. The slit surface part includes a plasma meniscus fixing part formed in an area of relatively higher plasma density in the slit longitudinal direction to fixingly maintain a plasma meniscus of the plasma and a plasma meniscus non-fixing part formed in an area of relatively lower plasma density in the slit longitudinal direction to movably maintain the plasma meniscus of the plasma in the beam extraction direction.