Gas Laser Purification Column and Booster Pump Control
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Solution Overview
Problem
Gas laser apparatuses used in semiconductor exposure devices face challenges in maintaining the purity of laser gases, leading to impurities that absorb pulse laser light and degrade discharge conditions, resulting in unstable output of desired pulse laser energy.
Innovation Solution
A gas laser apparatus with a purification system that includes a laser chamber connected to a first and second laser gas supply source with different halogen gas concentrations, a purification column to remove halogen gases and compounds, and a booster pump to raise gas pressure, controlled by a system that calculates and adjusts the gas supply to maintain optimal gas composition and pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a gas laser apparatus operates continuously to maintain productivity, then laser output is sustained, but impurities accumulate in the laser gas leading to degraded discharge conditions and unstable output
Solution Approach 1:
The patent implements a gas replacement system that periodically discards accumulated impure laser gas and replaces it with fresh laser gas. The control unit monitors discharge conditions and triggers gas replacement when impurity levels degrade performance, thereby restoring stable laser output without interrupting overall productivity.
Solution Approach 2:
The patent maintains continuous laser operation by implementing rapid gas replacement that occurs during or between pulse sequences. The gas supply unit and control unit work together to replenish fresh gas quickly, ensuring the laser can resume productive operation immediately after gas replacement, minimizing interruption to the useful action.
2Reliability
If laser gas is frequently replaced to maintain gas purity, then output stability is improved, but gas consumption increases
Solution Approach 1:
The control unit continuously monitors discharge conditions and laser output characteristics to detect when impurity accumulation begins to degrade performance. Based on this feedback, the system determines the optimal moment to replace gas, replacing it only when necessary rather than on a fixed schedule, thereby minimizing gas consumption while maintaining output stability.
Solution Approach 2:
Instead of complete gas replacement, the patent introduces a controlled amount of fresh laser gas to dilute and replace a portion of the impure gas. This partial replacement action is sufficient to restore discharge conditions and output stability without consuming excessive amounts of expensive laser gas.
3Power
If high pressure is applied to the laser gas to improve energy density, then laser output energy is enhanced, but discharge conditions become harder to control
Solution Approach 1:
The patent dynamically adjusts gas pressure parameters based on real-time monitoring of discharge conditions. The control unit modifies pressure settings to optimize the balance between achieving sufficient energy density for high power output and maintaining discharge stability, preventing pressure from becoming too high and causing control difficulties.
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 system effectively replaces impure gases with purified ones, reducing consumption and maintaining long-term stability of pulse laser energy output by controlling the gas composition and pressure within the laser chamber.
Implementation Method 1
a purification column that removes at least a part of the halogen gas and a halogen compound from at least a part of a gas exhausted from the laser chamber
Data Source
AI summary
A gas laser apparatus may include: a laser chamber connected through a first control valve to a first laser gas supply source that supplies a first laser gas containing a halogen gas; a purification column that removes at least a part of the halogen gas and a halogen compound from at least a part of a gas exhausted from the laser chamber; a booster pump; and a controller that calculates, on a basis of a first amount of a gas supplied from the booster pump to the laser chamber, a second amount of the first laser gas that is to be supplied to the laser chamber and controls the first control valve on a basis of a result of the calculation of the second amount.