Discharge Electrodes with Capturing Grooves for EUV Light Sources
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Solution Overview
Problem
High-speed rotation of discharge electrodes in EUV light source devices leads to centrifugal force causing high temperature plasma material to adhere to areas unnecessary for plasma generation, resulting in scattering and contamination within the chamber, while cooling challenges arise from immersion depth limitations.
Innovation Solution
Disc-shaped discharge electrodes with concentric capturing grooves to trap high temperature plasma material on areas unnecessary for plasma generation, combined with a material removing mechanism to prevent overflow and maintain electrode integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the discharge electrodes rotate at high speed to enable high repetition rate EUV radiation, then the productivity is improved, but the high temperature plasma material scatters and contaminates the chamber
Solution Approach 1:
The electrode surface is segmented into multiple functional zones by forming capturing grooves that divide the surface into a plasma generation area and a material capture area. This segmentation prevents the uncontrolled scattering of plasma material while maintaining high rotation speeds for high repetition rate EUV radiation.
Solution Approach 2:
The harmful plasma material that would otherwise scatter and contaminate the chamber is extracted from the harmful path by capturing it in dedicated grooves on the electrode surface. This removes the contamination problem while preserving the beneficial high-speed rotation for high productivity.
2Productivity
If the discharge electrodes rotate at high speed to improve EUV radiation repetition rate, then the productivity is improved, but the centrifugal force causes plasma material to adhere to areas unnecessary for plasma generation
Solution Approach 1:
Different regions of the electrode surface are given different local qualities through the capturing grooves. The plasma generation area maintains its functional properties while the grooved areas are designed specifically to capture and retain plasma material, preventing its migration to non-functional regions even at high rotation speeds.
3Temperature
If the immersion depth of the discharge electrodes in the plasma material is increased to improve cooling, then the temperature is reduced, but the electrode structure becomes more complex
Solution Approach 1:
Instead of increasing immersion depth in the vertical dimension, the cooling function is achieved by adding horizontal dimension features (capturing grooves) on the electrode surface. This provides effective plasma material contact for cooling without requiring increased vertical immersion depth, thereby avoiding structural 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
Effectively suppresses the scattering of high temperature plasma material at high rotation speeds, reducing contamination and maintaining electrode stability through efficient plasma material capture and removal.
Implementation Method 1
High-speed rotation of discharge electrodes leads to centrifugal force causing high temperature plasma material to adhere to areas unnecessary for plasma generation
Implementation Method 2
The high temperature plasma material 14 which is moved into the discharge space is irradiated with the laser beam 17 emitted from a laser source 17a. Upon irradiation with the laser beam 17, the high temperature plasma material 14 evaporates.
Implementation Method 3
A pulse discharge is triggered between the discharge electrodes 2a, 2b, and a plasma P is produced from the high temperature plasma material 14
Data Source
AI summary
Each of two discharge electrodes is partially immersed in a container, and rotations of the electrode cause a high-temperature plasma material adhering to the electrode to be conveyed into a discharge space. EUV light is emitted by generating a pulse discharge between the electrodes in a state where the high-temperature plasma material is vaporized. A plurality of capturing grooves for capturing the high-temperature plasma material are provided in the form of a plurality of concentric circles near the outer periphery of each discharge electrode. When each discharge electrode rotates, the high-temperature plasma material, which adheres to an area unnecessary for plasma generation, flows into the capturing grooves. As a result, the film thickness of the high-temperature plasma material does not increase very much at the outer periphery of each electrode, and it is possible to suppress the scattering of the high-temperature plasma material into a chamber interior.