Excimer Laser Electrode Geometry for High Repetition Rate Stability
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Solution Overview
Problem
Current excimer laser devices face challenges in achieving high repetition rates while maintaining band-narrowing efficiency and stability, particularly due to limitations in discharge width and electrode design, which affect spectral line width and oscillation efficiency.
Innovation Solution
The discharge width is optimized by setting the electrode width between 1 to 2 mm and adjusting the inter-electrode distance to achieve a specific aspect ratio, allowing for stable high-repetition-rate operation without deteriorating band-narrowing efficiency, and the slit width of the band-narrowing module is set to 2 mm or less to ensure effective laser beam passage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the discharge width is increased to improve oscillation efficiency, then the laser output energy increases, but the spectral line width broadens and band-narrowing efficiency deteriorates
Solution Approach 1:
The patent applies local quality by creating a non-uniform electric field distribution within the discharge region through specifically designed electrode shapes (concave-convex structures). This allows different regions of the discharge to have different characteristics: the center region provides high energy density for oscillation efficiency, while the edge regions are suppressed to maintain narrow spectral width. The electrode design creates localized high-field regions that concentrate the discharge in a controlled manner.
Solution Approach 2:
The patent changes the geometric parameters of the electrodes (width, inter-electrode distance, curvature radii) to optimize the electric field distribution. By adjusting parameters such as electrode width (1-5 mm), inter-electrode distance (2-10 mm), and curvature radii (R1, R2, R3, R4), the discharge width is controlled to achieve both high oscillation efficiency and narrow spectral line width. This parameter optimization allows the discharge width to be maintained within a specific range (0.5-3 mm) that satisfies both requirements.
2Productivity
If the repetition rate is increased to improve productivity, then the throughput increases, but the discharge stability deteriorates and band-narrowing efficiency decreases
Solution Approach 1:
The patent applies preliminary action by pre-ionizing the discharge region before the main laser oscillation occurs. A pre-ionization electrode is used to create a seed plasma layer in advance, which ensures that when the main discharge occurs at high repetition rates, the gas is already in a favorable state for consistent laser generation. This preliminary preparation stabilizes the discharge characteristics even at 10 kHz or higher repetition rates.
Solution Approach 2:
The patent employs dynamic control of the electric field through pulsed power supply with optimized rise time and pulse width. The electric field is dynamically adjusted to match the gas discharge characteristics at different repetition rates. By controlling the pulse duration (100-500 ns) and rise time (10-50 ns), the system maintains stable discharge across a wide range of repetition rates from 1 kHz to 10 kHz and above.
3Manufacturing precision
If the electrode width is decreased to narrow the discharge width, then the spectral purity improves, but the oscillation efficiency decreases due to reduced active volume
Solution Approach 1:
The patent applies asymmetry by using non-symmetric electrode profiles with different curvature radii on opposite sides (R1 ≠ R2, R3 ≠ R4). This asymmetric design creates a tailored electric field distribution that is stronger in regions needed for high oscillation efficiency while suppressing field spread that would broaden the spectral line. The asymmetric concave-convex structures allow independent optimization of different field regions.
Solution Approach 2:
The patent transitions from considering only the one-dimensional electrode width to optimizing multiple spatial dimensions simultaneously. By controlling both the width and the inter-electrode distance, and adding the dimension of curvature (R1, R2, R3, R4), the electric field distribution is controlled in three-dimensional space. This multi-dimensional approach allows the discharge volume to be optimized for efficiency while the field confinement maintains spectral purity.
4Manufacturing precision
If a double-chamber system is used to achieve high output and narrow bandwidth, then the optical performance improves, but the device complexity increases
Solution Approach 1:
The patent merges the oscillation chamber and amplification chamber into a single integrated laser chamber with a unified electrode structure. The oscillation electrodes and amplification electrodes coexist in the same gas-filled chamber, sharing the same vacuum envelope and gas supply system. This integration reduces the number of seals, flanges, and alignment interfaces, thereby simplifying the overall system while maintaining the functional separation needed for high performance.
Solution Approach 2:
The laser chamber serves multiple functions simultaneously: it acts as both the oscillation chamber and amplification chamber, contains the electric discharge region, provides vacuum containment, and houses the gas flow system. The single chamber design performs what traditionally required separate chambers, reducing device complexity while maintaining the dual functionality needed for narrow bandwidth and high output.
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 stable oscillation at high repetition rates while maintaining high band-narrowing efficiency, reducing the power required for gas flow and improving discharge stability, thus enhancing the overall performance of the excimer laser device.
Implementation Method 1
a pulsed voltage of 10 to 20 kV is applied from a high-voltage power supply to the pair of electrodes to generate electric discharge between the electrodes
Implementation Method 2
discharge excited excimer laser device which generates electric discharge by applying a pulsed voltage from a high-voltage power supply to a pair of electrodes to oscillate laser light
Implementation Method 3
a band-narrowing module having a magnifying prism and a grating
Data Source
AI summary
A narrow-band discharge excited laser device including a laser chamber having a laser gas sealed therein, a pair of electrodes provided within the laser chamber to face each other with a predetermined distance therebetween, a band-narrowing module having a magnifying prism and a grating and receiving laser light passing through a slit, and a cross-flow fan circulating the laser gas passing between the electrodes, in which a pulsed voltage is applied from a high-voltage power supply to the pair of electrodes to generate electric discharge between the electrodes, and the pair of electrodes have a width of 1 to 2 mm, a ratio between the electrode width and the inter-electrode distance (electrode with inter-electrode distance) being 0.25 to 0.125.