Segmented Cathode Cap for Plasma Generator Sputtering Resistance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In ion implanters, the cathode cap used in indirectly heated cathode type plasma generators wears down due to plasma sputtering, leading to unstable ion generation and increased power consumption as thicker caps are needed for longevity, which raises costs and maintenance frequency.
Innovation Solution
A plasma generator with a cathode cap that protrudes into the arc chamber and has a radial width that decreases inwardly, combined with a magnetic field to restrict electron movement and enhance plasma generation efficiency, and a thermal electron emitter with a cathode cap of a truncated conical shape to efficiently emit thermal electrons.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If the thickness of the cathode cap is increased to extend the lifetime of the ion source, then the durability of the cathode cap is improved, but the input energy amount necessary to sufficiently heat the cap increases
Solution Approach 1:
The cathode cap is divided into multiple sections (first cathode cap and second cathode cap) with different thicknesses. The first cathode cap has a larger thickness to withstand sputtering in high-density plasma regions, while the second cathode cap has a smaller thickness to reduce heating energy requirements. This segmentation allows the structure to simultaneously achieve both durability and energy efficiency.
Solution Approach 2:
Different regions of the cathode cap are given different thicknesses based on their functional requirements. The region exposed to high-density plasma (first cathode cap) is made thicker for durability, while the region requiring efficient heating (second cathode cap) is made thinner. This local quality variation resolves the contradiction between durability and energy consumption.
2Reliability
If the thickness of the cathode cap is increased to withstand sputtering, then the reliability of ion generation is improved, but the power supply cost increases
Solution Approach 1:
The cathode cap is segmented into two parts with different thicknesses. The first cathode cap with larger thickness ensures reliable ion generation by withstanding sputtering in plasma regions, while the second cathode cap with smaller thickness reduces the overall power supply requirement by minimizing the volume that needs to be heated.
Solution Approach 2:
The cathode cap structure implements local quality variation where only the necessary regions are made thick for reliability, while other regions are kept thin to reduce power consumption. This resolves the contradiction between maintaining reliable ion generation and reducing power supply costs.
3Duration of action of stationary object
If a thicker cathode cap is used to extend device lifetime, then the durability is improved, but the maintenance frequency increases due to higher power consumption
Solution Approach 1:
The cathode cap is divided into first and second parts with different thicknesses. The first cathode cap provides durability against sputtering to extend device lifetime, while the second cathode cap reduces heating energy requirements to improve operational efficiency and reduce maintenance frequency.
Solution Approach 2:
By giving different thicknesses to different regions of the cathode cap, the invention achieves both extended device lifetime through improved durability and enhanced operational efficiency through reduced power consumption, thereby reducing maintenance frequency.
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 improves the durability and longevity of the cathode cap, reduces the energy required to heat it, and enhances plasma generation efficiency by directing thermal electrons effectively into the arc chamber, thereby extending device lifetime and reducing operational costs.
Implementation Method 1
The indirectly heated cathode type plasma generator heats a filament by allowing an electric current to flow through the filament to generate thermal electrons, and heats a cathode by the thermal electrons. Thermal electrons generated by the heated cathode are accelerated within an arc chamber
Implementation Method 2
a magnetic field generator configured to apply a magnetic field to the plasma generation region
Implementation Method 3
Thermal electrons generated by the heated cathode are accelerated within an arc chamber and collided with source gas molecules in the arc chamber, so that atoms included in the source gas molecules are ionized to generate plasma
Implementation Method 4
The cathode cap protrudes toward the inside of the arc chamber in the axial direction and has a shape of which a width in the radial direction perpendicular to the axial direction becomes smaller toward the inside of the arc chamber
Data Source
AI summary
A plasma generator includes: an arc chamber having a plasma generation region in which plasma is generated in the inside thereof; a magnetic field generator configured to apply a magnetic field to the plasma generation region; and a cathode configured to extend in an axial direction along an applying direction of the magnetic field applied to the plasma generation region and provided with a cathode cap that emits thermal electrons at a front end thereof. The cathode cap protrudes toward the inside of the arc chamber in the axial direction and has a shape of which a width in the radial direction perpendicular to the axial direction becomes smaller toward the inside of the arc chamber.