Excimer Laser Pulse Circuit Layout for Uniform Electrode Discharge
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Solution Overview
Problem
Gas laser devices used in semiconductor exposure apparatuses face challenges with chromatic aberration due to large spectral line widths of KrF and ArF excimer laser devices, leading to decreased resolution and increased maintenance costs from uneven discharge between electrodes, which affects energy efficiency and wear.
Innovation Solution
A gas laser device configuration with a pair of discharge electrodes and multiple capacitors, where magnetic switches with varying Vt products are arranged along the electrode axis to reduce potential differences and suppress uneven discharge, including a second magnetic switch closer to the electrode center and additional switches to balance potential timing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single magnetic switch is used in the pulse compression circuit, then the device complexity is reduced, but uneven discharge between electrodes occurs due to potential differences along the electrode length
Solution Approach 1:
The pulse compression circuit is segmented into multiple sections, each with its own magnetic switch. The discharge electrode is divided into multiple regions along its longitudinal direction, with each region connected to a separate magnetic switch. This segmentation allows independent control of discharge timing at different positions, preventing uneven discharge while maintaining manageable system complexity through modular architecture.
Solution Approach 2:
Different magnetic switches are positioned at different locations along the electrode, and capacitors are arranged with different capacitance values corresponding to different positions. This local differentiation ensures that each section of the electrode receives appropriately timed and sized voltage pulses, achieving uniform discharge characteristics across the entire electrode length rather than applying a uniform solution throughout.
2Reliability
If multiple capacitors with different capacitance values are arranged along the electrode, then discharge uniformity is improved, but the device complexity and manufacturing cost increase
Solution Approach 1:
The capacitance values of capacitors are systematically varied along the longitudinal direction of the electrode according to a predetermined gradient. By changing the capacitance parameter progressively rather than using identical values, the voltage application timing is optimized for each electrode section, achieving uniform discharge while following a regular pattern that simplifies design and manufacturing compared to arbitrary arrangements.
3Manufacturing precision
If the spectral line width is narrowed using a line narrowing module, then chromatic aberration is reduced and resolution is improved, but the device complexity and energy loss increase
Solution Approach 1:
The laser operates in pulsed mode with periodic discharge cycles between the electrodes. By controlling the timing and duration of each pulse through the arranged capacitors and magnetic switches, the laser produces periodic bursts of coherent light. This periodic operation enables high-resolution output through controlled pulse characteristics without requiring additional line narrowing optical components, thereby avoiding the complexity and energy losses associated with such modules.
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 reduces potential differences and suppresses uneven discharge, enhancing energy efficiency and extending the lifespan of electrodes by minimizing wear, thereby improving the resolution and reliability of the gas laser device.
Implementation Method 1
a plurality of capacitors arranged along the predetermined direction, each of the capacitors having one terminal electrically connected to one of the discharge electrodes and the other terminal electrically connected to the other of the discharge electrodes
Implementation Method 2
a pair of discharge electrodes having a longitudinal direction oriented along a predetermined direction and facing each other with a space therebetween
Implementation Method 3
a first magnetic switch and a second magnetic switch each electrically connected to the one discharge electrode and the one terminal of each of the capacitors and electrically connected to each other in parallel
Data Source
AI summary
A gas laser device includes a chamber configured to enclose a laser gas as including a pair of discharge electrodes having a longitudinal direction oriented along a predetermined direction and facing each other with a space therebetween; a plurality of capacitors arranged along the predetermined direction, each of the capacitors having one terminal electrically connected to one of the discharge electrodes and the other terminal electrically connected to the other of the discharge electrodes; and first and second magnetic switches each electrically connected to the one discharge electrode and the one terminal of each of the capacitors and electrically connected to each other in parallel. The second magnetic switch is arranged closer to a center of the one discharge electrode in the predetermined direction than the first magnetic switch, and a Vt product of the first magnetic switch is smaller than a Vt product of the second magnetic switch.