Ion Source Arc Chamber Shielding for Phosphorus Outgassing
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Solution Overview
Problem
The accumulation of phosphorus in ion source components leads to outgassing, which can increase pressure and reduce the effectiveness of ion implantation systems, particularly during high-temperature processes.
Innovation Solution
Implementing thermal radiation shields to maintain elevated temperatures of ion source components, specifically the extraction aperture plate, to reduce phosphorus storage and minimize outgassing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional ion source components are used without thermal radiation shields, then the structure is simple and easy to manufacture, but phosphorus accumulates in components leading to outgassing and increased chamber pressure
Solution Approach 1:
A thermal radiation shield is introduced as an intermediary component between the arc chamber interior and the extraction aperture plate exterior. This shield mediates heat transfer, maintaining elevated temperatures of the extraction aperture plate to prevent phosphorus condensation and outgassing, thereby resolving the contradiction between operational stability and structural simplicity
Solution Approach 2:
The invention changes the temperature parameter of the extraction aperture plate by introducing thermal radiation shields that maintain elevated temperatures. This parameter change prevents phosphorus from condensing and storing on cold surfaces, eliminating outgassing issues while maintaining a relatively simple overall structure
2Productivity
If high arc power conditions are used for As++++ ion implantation, then higher beam currents are achieved, but outgassing of stored phosphorus significantly reduces available current due to electron capture reactions
Solution Approach 1:
The thermal radiation shield performs preliminary action by maintaining elevated temperatures of the extraction aperture plate before phosphorus can accumulate and outgas during high power operation. This preventive measure ensures that when high arc power conditions are applied for maximum beam current, the vacuum level remains stable without phosphorus outgassing interfering with electron capture reactions
3Reliability
If ion source components are maintained at elevated temperatures to reduce phosphorus storage, then outgassing is minimized, but additional thermal management components are required
Solution Approach 1:
The thermal radiation shield serves as a focused intermediary that addresses thermal management needs locally at the extraction aperture plate without requiring system-wide thermal management complexity. It selectively maintains elevated temperatures where phosphorus storage is problematic while leaving other components at their normal operating temperatures
Solution Approach 2:
The invention applies local quality by implementing thermal radiation shields only at specific locations (the extraction aperture plate) where phosphorus storage and outgassing are most problematic, rather than heating the entire ion source system. This localized approach maintains operational consistency while minimizing additional system complexity
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
Stabilizes ion beam formation and extends the lifetime of ion sources by reducing phosphorus outgassing, allowing for higher beam currents and improved operational consistency across various implantation processes.
Implementation Method 1
one or more thermal radiation shields are positioned between the one or more components and an external environment directly outside of the arc chamber. The one or more thermal radiation shields limit a transfer of the thermal radiation from the chamber environment to the external environment
Implementation Method 2
Ion sources in ion implanters typically generate the ion beam by ionizing a source material in an arc chamber
Data Source
AI summary
An arc chamber for an ion source provides a source of thermal radiation positioned within an interior region of the arc chamber. One or more components generally enclose the interior region of the arc chamber, defining an arc chamber environment within the interior region of the arc chamber. A thermal radiation shield is positioned between the one or more components and an external environment outside of the arc chamber and limits a transfer of the thermal radiation from the chamber environment to the external environment. The one or more components can be an extraction aperture plate having an extraction aperture defined therethrough. The thermal radiation shield is positioned proximate to, and covers at least approximately 75% of the exterior surface of the extraction aperture plate to primarily prevent thermal radiation for passing through the extraction aperture plate.