Laser Apparatus Electrode Gap Control for Spectral Narrowing
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Solution Overview
Problem
Current semiconductor exposure apparatuses face challenges with color aberration due to wide spectral line widths in KrF and ArF excimer laser apparatuses, leading to degradation in resolution, which necessitates the narrowing of the laser beam's spectral line width to minimize color aberration.
Innovation Solution
A laser apparatus with an optical resonator, including an output coupler, a laser chamber with a laser medium, and a pair of discharge electrodes with an electrode gap varying section, where the gap between the electrodes is controlled based on measured beam parameters to adjust the laser beam's characteristics, such as beam size, divergence, and pulse energy, to achieve the desired spectral line width.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the spectral line width of the laser beam is narrowed to minimize color aberration, then the resolution of the semiconductor exposure apparatus is improved, but the device complexity increases due to the need for line narrowing modules such as etalons and gratings inside the laser resonator
Solution Approach 1:
The patent changes the physical parameter of the discharge electrode gap to control and narrow the spectral line width of the laser beam. By adjusting the gap distance between discharge electrodes, the laser apparatus achieves spectral narrowing without requiring additional line narrowing modules, thus improving resolution while avoiding increased device complexity
Solution Approach 2:
The patent extracts and removes the line narrowing modules (etalons, gratings) from the laser resonator system. Instead of adding these complex components, the invention uses the discharge electrode gap configuration to inherently achieve spectral line width control, thereby simplifying the overall device structure while maintaining high resolution performance
2Object-affected harmful factors
If line narrowing modules including etalons and gratings are provided inside the laser resonator to narrow the spectrum width, then the color aberration is reduced, but the device complexity and structural complexity increase
Solution Approach 1:
The patent uses parameter change of the discharge electrode gap to control the spectral line width and eliminate color aberration. This approach replaces complex optical components with a simple geometric parameter adjustment, reducing structural complexity while effectively addressing the harmful effect of color aberration
Solution Approach 2:
The discharge electrode gap acts as an intermediary mechanism that indirectly controls the spectral properties of the laser beam. Instead of directly inserting line narrowing modules into the optical path, the patent uses the electrode gap as a mediator to achieve spectral control through its influence on the discharge characteristics and laser emission
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 allows for precise control of the laser beam parameters, effectively reducing color aberration and improving the resolution of the semiconductor exposure apparatus by dynamically adjusting the electrode gap to match target beam parameters, thereby enhancing the apparatus's performance.
Implementation Method 1
a pair of discharge electrodes disposed inside the laser chamber; a laser beam measurement section disposed in an optical path of a laser beam outputted from the output coupler, the laser beam resulting from electric discharge between the discharge electrodes
Data Source
AI summary
There may be provided a laser apparatus including: an optical resonator including an output coupler; a laser chamber containing a laser medium and disposed in an optical path inside the optical resonator; a pair of discharge electrodes disposed inside the laser chamber; an electrode gap varying section configured to vary a gap between the discharge electrodes; a laser beam measurement section disposed in an optical path of a laser beam outputted from the output coupler, the laser beam resulting from electric discharge between the discharge electrodes; and a controller configured to control the gap between the discharge electrodes through activating the electrode gap varying section, based on a beam parameter of the laser beam measured by the laser beam measurement section.