Gas Laser Pulse Circuit for Stable Cathode Voltage
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Solution Overview
Problem
Gas laser devices used in semiconductor exposure apparatuses face issues with chromatic aberration due to wide spectral line widths, leading to decreased resolution, and existing solutions like line narrowing modules do not fully address the problem of peak voltage fluctuations that increase arc discharge intensity and reduce laser output stability.
Innovation Solution
A gas laser device configuration with a power source, main capacitor, solid-state switch, magnetic pulse compression circuits, and a regenerative transformer, along with specific adjustments to the pulse power module, is used to control the potential of the cathode electrode and suppress peak voltage fluctuations, thereby reducing chromatic aberration and improving laser output stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a line narrowing module is provided in the laser resonator to narrow spectral line width, then chromatic aberration is reduced and resolution is improved, but peak voltage fluctuations increase and arc discharge intensity increases
Solution Approach 1:
The invention changes the electrical parameters of the pulse power module by controlling the potential of the cathode electrode to be within -200V to 200V during 0.5μs to 20μs after main discharge. This parameter control suppresses peak voltage fluctuations and reduces arc discharge intensity, thereby improving laser output stability while maintaining the resolution benefits of the line narrowing module
2Duration of action of stationary object
If the cathode electrode potential is not controlled, then arc discharge intensity increases and electrode lifetime decreases, but laser output stability is improved
Solution Approach 1:
The invention implements feedback control by monitoring and controlling the cathode electrode potential to remain within -200V to 200V during the critical period after main discharge. This feedback mechanism suppresses peak voltage fluctuations that would otherwise increase arc discharge intensity and reduce electrode lifetime, while simultaneously improving laser output stability through reduced electrical instability
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
The solution effectively suppresses peak voltage fluctuations, reducing arc discharge intensity and extending the lifetime of discharge electrodes while improving energy stability and resolution in the gas laser device.
Implementation Method 1
a step-up transformer in which a primary side thereof is connected in parallel to the main capacitor via the solid-state switch
Implementation Method 2
a first magnetic pulse compression circuit including a first transfer capacitor to which charges in the main capacitor are transferred and a first magnetic switch
Implementation Method 3
a pair of discharge electrodes configured of a cathode electrode and an anode electrode and connected in parallel to the peaking capacitor
Implementation Method 4
a regenerative transformer in which a primary side thereof is connected in parallel to the main capacitor and a secondary side thereof is connected to the first transfer capacitor, and which is configured to transfer charges generated by the pair of discharge electrodes to the main capacitor after main discharge
Data Source
AI summary
A gas laser device includes a power source, a main capacitor, a solid-state switch, a step-up transformer, a first magnetic pulse compression circuit including a first transfer capacitor and a first magnetic switch, and connected to a secondary side of the step-up transformer, a second magnetic pulse compression circuit including a second transfer capacitor and a second magnetic switch, and connected subsequently to the first magnetic pulse compression circuit, a peaking capacitor connected subsequently to the second magnetic pulse compression circuit, a pair of discharge electrodes, a regenerative transformer transferring charges generated by the discharge electrodes to the main capacitor after main discharge, and a reset circuit resetting the first magnetic switch and the second magnetic switch. Potential of the cathode electrode in a period of 0.5 μs to 20 μs both inclusive after the main discharge starts is within a range of −200 V to 200 V both inclusive.