Laser Apparatus Divergence Control for Semiconductor Exposure
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Solution Overview
Problem
Semiconductor exposure apparatuses face challenges in maintaining stable laser beam characteristics, particularly divergence, pointing, and position, especially during switching operations from low-load to high-load or vice versa, leading to potential color aberration and decreased resolution due to wide spectral line widths in KrF and ArF excimer laser systems.
Innovation Solution
A laser apparatus comprising a first and second optical element to adjust laser beam divergence in perpendicular directions, a measuring unit to assess these divergences, and a controller to adjust the optical elements based on measured values, ensuring the laser beam characteristics remain within predetermined ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a gas laser apparatus (KrF or ArF excimer laser) is used as an exposure light source, then high-resolution semiconductor exposure is enabled through short wavelength output, but the spectral line width becomes wide (350-400 pm) causing color aberration and resolution decrease
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the divergence of the laser beam in both horizontal and vertical directions using optical elements (such as cylindrical lenses or mirrors). This adjustment compensates for the wide spectral line width effect and color aberration, maintaining resolution despite the inherent wide bandwidth of excimer lasers. The measuring unit detects divergence changes, and the controller modifies optical parameters to keep the beam characteristics within acceptable ranges.
2Adaptability or versatility
If the laser apparatus operates under varying load conditions, then flexibility and adaptability are improved, but laser beam characteristics (divergence, pointing, position) become unstable
Solution Approach 1:
The patent implements a feedback control system where a measuring unit continuously monitors the divergence of the laser beam in both horizontal and vertical directions. The controller receives these measurements and dynamically adjusts optical elements to compensate for deviations caused by load switching. This closed-loop feedback mechanism maintains beam characteristic stability despite changes in operational load, preventing color aberration and resolution degradation.
Solution Approach 2:
The patent employs dynamic adjustment of optical elements to adapt laser beam characteristics in real-time. The optical elements (such as adjustable mirrors or lenses) are modified based on measured divergence values, allowing the system to maintain stable beam properties across varying load conditions. This dynamic compensation approach enables the laser apparatus to transition between low-load and high-load operations without significant degradation in beam quality.
3Stability of the object's composition
If optical elements are added to adjust and stabilize laser beam divergence, then beam characteristic stability is improved, but device complexity increases
Solution Approach 1:
The patent applies local quality by using separate optical elements to adjust divergence independently in horizontal and vertical directions. Each optical element is positioned and configured to address specific directional divergence issues, allowing targeted correction without requiring complete system redesign. This localized approach stabilizes beam characteristics while minimizing overall system complexity compared to a fully integrated solution.
Data Source
AI summary
A laser apparatus may include a first laser resonator configured to generate a laser beam, a first optical element configured to adjust a divergence in a first direction of the laser beam, a second optical element configured to adjust a divergence in a second direction of the laser beam, a measuring unit configured to measure the divergence in the first direction and the divergence in the second direction of the laser beam, and a controller configured to control one or both of the first optical element and the second optical element based on the divergence in the first direction and the divergence in the second direction of the laser beam both measured by the measuring unit.