Master Oscillator Spectral Bandwidth Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current gas laser apparatuses used in semiconductor exposure devices suffer from chromatic aberration due to wide natural oscillation amplitudes, leading to reduced resolution, which necessitates the narrowing of spectral bandwidth to mitigate this issue.
Innovation Solution
A master oscillator system with a grating functioning as a resonator mirror, a spectral bandwidth tuning unit, and a controller to adjust the spectral bandwidth based on stored control values, along with a detection unit to monitor and adjust the spectral bandwidth of the laser beam.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If gas laser apparatus is used for semiconductor exposure, then exposure capability is provided, but chromatic aberration occurs due to wide natural oscillation amplitude, leading to reduced resolution
Solution Approach 1:
The patent applies parameter changes by narrowing the spectral bandwidth of the laser beam from its natural wide oscillation amplitude (350-400 pm) to a controlled narrow bandwidth. This is achieved through providing a line narrowing module with a line narrowing element (etalon or grating) within the laser resonator, which changes the spectral parameter to reduce chromatic aberration and improve resolution while maintaining exposure capability
2Manufacturing precision
If line narrowing module is provided to narrow spectral bandwidth, then chromatic aberration is reduced, but device complexity increases
Solution Approach 1:
The patent merges the line narrowing function into the existing laser resonator structure by providing a line narrowing module that integrates the etalon or grating element within the resonator. This combining approach reduces the need for separate external narrowing components, thereby controlling device complexity while achieving the required spectral bandwidth narrowing for improved resolution
3Manufacturing precision
If spectral bandwidth is narrowed using line narrowing element, then resolution is improved, but control precision over spectral bandwidth is insufficient
Solution Approach 1:
The patent implements feedback control by providing a controller that adjusts the spectral bandwidth tuning unit based on stored control values corresponding to desired spectral bandwidths. The controller monitors and regulates the spectral bandwidth parameter, enabling precise control and maintaining the narrow bandwidth required for high resolution while compensating for any drift or variations
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 spectral bandwidth, reducing chromatic aberration and enhancing the resolution of semiconductor exposure devices by stabilizing the spectral bandwidth of the laser beam.
Implementation Method 1
a grating configured to function as one resonator mirror in an optical resonator
Data Source
AI summary
A master oscillator system may include a grating configured to function as one resonator mirror in an optical resonator, a spectral bandwidth tuning unit configured to tune the spectral bandwidth of a laser beam transmitted within the optical resonator, a storage unit configured to store a control value of the spectral bandwidth tuning unit corresponding to a desired spectral bandwidth and a controller configured to control the spectral bandwidth tuning unit based on the control value stored in the storage unit.