Ion Generator Thermal Reflector Narrow Gap Design
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Solution Overview
Problem
In ion implanters, the degradation of thermal insulation properties in the tubular member due to metal deposition from halide source gases leads to frequent maintenance needs, reducing productivity and increasing costs.
Innovation Solution
An ion generator and thermal electron emitter design featuring a cylindrical thermal reflector with a narrow gap structure between the cathode and reflector, which reduces plasma infiltration and maintains thermal insulation, thereby minimizing maintenance requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the cathode cap is maintained at high temperature to improve thermal electron generation efficiency, then the generation efficiency of thermal electrons is improved, but metal material deposits on the tubular member surface, degrading thermal insulation properties
Solution Approach 1:
A thermal insulator is introduced as an intermediary component between the cathode cap and the tubular member. This thermal insulator prevents direct thermal conduction while allowing the cathode cap to maintain high temperature for efficient thermal electron generation. The thermal insulator is positioned to extend from the cathode cap toward the tubular member, creating a thermal barrier that prevents metal deposition on the tubular member surface.
2Use of energy by moving object
If the cathode cap is maintained at high temperature, then thermal electron generation efficiency is improved, but maintenance frequency increases due to metal deposition
Solution Approach 1:
The thermal insulator serves as a sacrificial intermediary that protects the tubular member from metal deposition. By placing the thermal insulator between the high-temperature cathode cap and the tubular member, the insulator prevents halide dissociation and metal deposition on the tubular member surface, thereby reducing maintenance frequency and improving productivity while allowing the cathode cap to operate at high temperature for efficient thermal electron generation.
3Reliability
If a wide gap exists between the cathode and thermal reflector, then thermal insulation is maintained, but plasma infiltrates and causes metal deposition
Solution Approach 1:
The gap between the cathode and thermal reflector is segmented into multiple regions with different widths. A narrow gap region is positioned at the lower part where plasma infiltration is most problematic, while a wide gap region is positioned at the upper part where thermal insulation is most critical. This segmentation allows the narrow gap to block plasma infiltration and prevent metal deposition, while the wide gap maintains thermal insulation properties.
4Temperature
If the tubular member has good thermal insulation properties, then cathode cap temperature stability is improved, but metal deposition occurs on the tubular member surface
Solution Approach 1:
The thermal insulator acts as a protective intermediary that prevents metal deposition on the tubular member surface while maintaining the tubular member's inherent good thermal insulation properties. The thermal insulator is positioned between the cathode cap and tubular member, allowing heat to be contained in the cathode cap region while preventing halide dissociation and metal deposition on the tubular member, thereby maintaining temperature stability without the harmful effect of metal deposition.
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 design enhances ion generation efficiency by maintaining cathode temperature stability, reducing maintenance frequency, and improving productivity while lowering operational costs.
Implementation Method 1
a filament is heated by a current to generate thermal electrons
Implementation Method 2
thermal electrons generated by the heated cathode are accelerated within an arc chamber
Implementation Method 3
the tubular member to which the cathode cap is attached desirably has good thermal insulation properties
Data Source
AI summary
An ion generator includes an arc chamber, a cathode that extends outward from the inside of the arc chamber in an axial direction and that emits a thermal electron into the arc chamber, a thermal reflector with a cylindrical shape provided around the cathode in a radial direction and extending in the axial direction, and a narrow structure configured to narrow a width in the radial direction of a gap between the cathode and the thermal reflector at a given position in the axial direction.