Coated Discharge Electrode Geometry for Stable Gas Laser Discharge
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Solution Overview
Problem
The existing gas laser apparatuses used in semiconductor exposure suffer from chromatic aberrations due to wide spectral linewidths, leading to reduced resolution, and the use of line narrowing modules to narrow the spectral linewidth results in unstable discharge and increased power consumption.
Innovation Solution
The discharge electrodes are designed with a specific shape and coating layer configuration where first corners are closer to the cathode, reducing the discharge space width and stabilizing the discharge, while incorporating a coating layer with varying thickness to minimize electric field concentration and electrode degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a line narrowing module is provided in the laser resonator to narrow the spectral linewidth, then chromatic aberrations are reduced and resolution is improved, but discharge stability deteriorates and power consumption increases
Solution Approach 1:
The patent changes the geometric parameters of the anode, specifically creating an asymmetric shape where the first corners are closer to the cathode than the second corners. This parameter change modifies the electric field distribution and discharge characteristics, achieving stable discharge without requiring a line narrowing module, thus resolving the contradiction between resolution improvement and discharge stability deterioration
Solution Approach 2:
The anode is designed with an asymmetric cross-sectional shape where the distance from the first corners to the cathode is shorter than the distance from the second corners to the cathode. This asymmetric configuration optimizes the discharge space width and electric field distribution, enabling stable discharge operation while maintaining the ability to achieve narrow spectral linewidth without additional modules
2Measurement precision
If a line narrowing module is provided in the laser resonator to narrow the spectral linewidth, then chromatic aberrations are reduced and resolution is improved, but power consumption increases
Solution Approach 1:
The patent modifies the anode geometric parameters to create an asymmetric shape with optimized corner positioning. This parameter optimization enables the laser to achieve narrow spectral linewidth and high resolution through improved discharge efficiency, eliminating the need for energy-consuming line narrowing modules
Solution Approach 2:
The invention extracts and removes the line narrowing module from the laser resonator system by achieving line narrowing functionality through the anode geometry itself. This eliminates the additional power consumption associated with separate line narrowing devices while maintaining high resolution performance
3Reliability
If the discharge space width is reduced to stabilize discharge, then discharge stability is improved, but electric field concentration increases causing electrode degradation
Solution Approach 1:
The patent applies local quality differentiation by creating distinct regions on the anode surface with different properties. The asymmetric corner configuration creates zones with varying electric field intensity, allowing the discharge space to be sufficiently narrow for stability while preventing excessive field concentration at any single point, thus protecting electrode durability
Solution Approach 2:
The anode cross-section is effectively segmented into different functional zones by the asymmetric corner configuration. The first corners create a discharge-optimized region closer to the cathode, while the second corners create a field-distribution region farther away, segmenting the electric field management to simultaneously achieve discharge stability and electrode protection
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 stabilizes the discharge, reduces power consumption, and prolongs electrode life by minimizing discharge space width and electric field concentration, thereby improving the resolution and efficiency of the gas laser apparatus.
Implementation Method 1
a gas laser apparatus in which a fluorine-containing laser gas is excited by discharge
Data Source
AI summary
Discharge electrodes include a cathode and an anode. The anode is disposed to face the cathode in a discharge direction perpendicular to a longitudinal direction of the cathode, and includes an electrode base 1, and a coating layer that covers a portion of a surface of the electrode base. First corners in a cross section perpendicular to the longitudinal direction connect first straight sections formed of first side surfaces that are side surfaces of the electrode base to a first curved section formed of a first discharge surface that is a discharge surface of the electrode base. The first corners are closer to the cathode in the discharge direction than second corners connecting second straight sections formed of second side surfaces that are side surfaces of the coating layer to a second curved section formed of a second discharge surface that is a discharge surface of the coating layer.