Ion Source Device Plasma Density Extraction
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Solution Overview
Problem
Ion source devices for ion implantation apparatuses face limitations in increasing plasma density near the ion beam extraction portion, leading to reduced extraction current, which is exacerbated by the short lifespan of the cathode when trying to enhance plasma density.
Innovation Solution
An ion source device with a cathode and repeller configuration where an external magnetic field is applied parallel to the axis connecting the cathode and repeller, and an opening is provided at the highest plasma density location on the repeller to extract the ion beam, allowing for higher plasma density extraction without increasing power supply or gas introduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If plasma density near the ion beam extraction portion is increased to increase extraction current, then productivity is improved, but cathode lifespan deteriorates
Solution Approach 1:
The invention applies different functional zones within the plasma generation region. The region near the cathode maintains lower plasma density to protect the cathode, while the region near the extraction slit achieves high plasma density through magnetic field concentration and plasma flow control, enabling high extraction current without cathode degradation
Solution Approach 2:
The invention introduces magnetic field lines as a spatial dimension to control plasma distribution. By adjusting magnetic field strength and configuration, plasma is guided along field lines to concentrate at the extraction slit region rather than uniformly distributing near the cathode, achieving spatial separation of plasma density zones
2Quantity of substance
If plasma density near the ion beam extraction portion is increased to increase extraction current, then beam current is improved, but power consumption increases
Solution Approach 1:
The magnetic field acts as an intermediary to concentrate and guide plasma to the extraction region without requiring additional power input. The plasma flow is controlled by magnetic field lines that direct ion movement toward the extraction slit, achieving high plasma density locally without increasing overall power consumption
Solution Approach 2:
The invention changes the magnetic field parameter (strength and configuration) to control plasma distribution. By optimizing magnetic field parameters, plasma is confined and concentrated at the extraction region where it is needed, rather than requiring increased power to achieve the same effect throughout the entire plasma chamber
3Quantity of substance
If plasma density near the ion beam extraction portion is increased to increase extraction current, then beam current is improved, but gas consumption increases
Solution Approach 1:
The invention creates a localized high-density plasma region at the extraction slit rather than maintaining high plasma density throughout the entire chamber. This localized approach concentrates gas utilization where ion generation is needed, reducing overall gas consumption while maintaining high extraction current
Solution Approach 2:
Magnetic field lines provide a spatial pathway that guides plasma and ion flow efficiently to the extraction region. This dimensional control ensures that introduced gas is effectively utilized in the extraction zone without requiring excessive gas flow rates, minimizing gas loss
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 enables a beam current increase of several tens of times the original plasma density, extending the cathode's lifespan by extracting ions from plasma with equivalent density to the cathode, while reducing power and gas requirements.
Implementation Method 1
a cathode that discharges thermal electrons for generating beam electrons that ionize neutral molecules
Implementation Method 2
beam electrons that ionize neutral molecules
Implementation Method 3
an external magnetic field F that is induced by a source magnetic field unit is applied to the space for plasma formation in a direction parallel to an axis that connects the cathode and the repeller
Implementation Method 4
a repeller that reflects the electrons back to the cathode
Implementation Method 5
plasma that is diffused to the front slit 20-1
Data Source
AI summary
An ion source device has a configuration in which a cathode is provided in an arc chamber having a space for plasma formation, and a repeller is disposed to face a thermal electron discharge face of the cathode by interposing the space for plasma formation therebetween. An external magnetic field that is induced by a source magnetic field unit is applied to the space for plasma formation in a direction parallel to an axis that connects the cathode and the repeller. An opening is provided in a place corresponding to a portion in the repeller with the highest density of plasma that is formed in the space for plasma formation, and an ion beam is extracted from the opening.