Gas Laser Resonator Beam Expander for Stable Exposure Resolution
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Solution Overview
Problem
Chromatic aberration occurs in gas laser devices with large spectral line widths, leading to decreased resolution in semiconductor exposure apparatuses, necessitating line-narrowing modules that can deteriorate over time.
Innovation Solution
A gas laser device configuration with a beam expander using a convex and concave cylindrical mirror arrangement to expand and collimate laser light, reducing linear polarization differences and minimizing beam width fluctuations, while using a drive mechanism to adjust mirror positions for optimal performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a line narrowing module is provided in the laser resonator to reduce spectral line width, then chromatic aberration is reduced and resolution is improved, but the optical elements in the line narrowing module deteriorate over time
Solution Approach 1:
The patent extracts the line-narrowing function from a separate module and integrates it into the laser resonator itself. The resonator's mirrors and optical path are designed to inherently narrow the spectral line width, eliminating the need for additional line-narrowing modules with fragile optical elements. This resolves the contradiction by achieving high resolution without compromising optical element durability.
2Stability of the object's composition
If the beam width of laser light is expanded to improve uniformity, then polarization differences are reduced, but the beam width becomes difficult to control
Solution Approach 1:
The patent employs dynamic control of the beam expander's magnification ratio, allowing it to be adjusted based on process requirements. By making the beam expansion ratio variable rather than fixed, the system can optimize both polarization uniformity and beam width control for different exposure conditions, resolving the contradiction between these two parameters.
3Manufacturing precision
If the beam width of laser light is reduced to improve focus, then resolution is improved, but polarization differences increase
Solution Approach 1:
The patent uses a beam expander with adjustable magnification ratio to dynamically control beam width. When high resolution is needed, the beam width is reduced while the system compensates by adjusting other parameters to maintain polarization uniformity. This dynamic adjustment capability allows the system to optimize for resolution without permanently sacrificing polarization stability.
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
Enhances laser light quality by maintaining consistent beam width and reducing polarization differences, thereby improving resolution and reducing the risk of optical element deterioration.
Implementation Method 1
a convex mirror including a reflection surface on which the laser light output from the chamber device is incident so that the first linear polarization in the laser light becomes S-polarization, and which reflects the laser light so that a beam width of the laser light is expanded
Implementation Method 2
a concave mirror including a reflection surface on which the laser light reflected by the convex mirror is incident so that the first linear polarization in the laser light becomes S-polarization, and which reflects the laser light toward the output coupling mirror so as to collimate the laser light so that the expanded beam width of the laser light becomes constant
Implementation Method 3
a polarizer arranged on an optical path of the laser light of the resonator, and configured to reduce, from the laser light, linear polarization whose polarization direction is different from a polarization direction of a first linear polarization
Data Source
AI summary
A gas laser device amplifies, using an amplifier, laser light output from a laser oscillator. The amplifier includes a chamber device, a resonator including an output coupling mirror and causing the laser light to resonate, a polarizer reducing linear polarization whose polarization direction is different from a polarization direction of a first linear polarization, and a beam expander. The beam expander includes a convex mirror including a reflection surface on which the laser light output from the chamber device is incident and which reflects the laser light so that a beam width of the laser light is expanded, and a concave mirror including a reflection surface on which the laser light reflected by the convex mirror is incident and which reflects the laser light toward the output coupling mirror so as to collimate the laser light so that the expanded beam width of the laser light becomes constant.