Optical Pulse Stretcher Deterioration Estimation From Temporal Waveforms
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Solution Overview
Problem
Chromatic aberration in semiconductor exposure apparatuses due to the large spectral line width of KrF and ArF excimer laser devices leads to decreased resolution, necessitating line-narrowed laser devices, and existing methods for estimating optical pulse stretcher deterioration require multiple measurement points, increasing complexity and time.
Innovation Solution
A method and device for estimating optical pulse stretcher deterioration by measuring and comparing temporal waveforms before and after pulse width extension, using a single measurement point and a processor to calculate deterioration based on these waveforms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple measurement points are used to estimate optical pulse stretcher deterioration, then measurement precision is improved, but measurement time and device complexity increase
Solution Approach 1:
The patent extracts the essential information needed for deterioration estimation from a single temporal waveform measurement. By focusing on specific parameters (pulse width, peak intensity, area) from one measurement point, the system achieves adequate estimation accuracy without requiring multiple measurement points, thus reducing measurement time while maintaining essential precision.
Solution Approach 2:
The patent establishes baseline characteristics of the optical pulse stretcher during initial calibration. These pre-stored reference values (pulse width, intensity, area) enable subsequent deterioration estimation using only single-point measurements, eliminating the need for multiple measurement points during routine monitoring while maintaining estimation accuracy through comparison with baseline data.
2Measurement precision
If multiple measurement points are used to estimate optical pulse stretcher deterioration, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent extracts only the necessary parameters (pulse width, peak intensity, area) from temporal waveforms and uses these extracted features for deterioration estimation. This selective extraction approach maintains measurement precision while avoiding the complexity of measuring and processing multiple parameters at multiple points, thus simplifying the measurement system.
Solution Approach 2:
The system performs preliminary calibration to establish baseline characteristics and stores these reference values for future comparisons. This pre-processing action enables single-point measurements to suffice for deterioration estimation, eliminating the need for complex multi-point measurement systems while maintaining adequate precision through comparison with stored baseline data.
3Manufacturing precision
If line narrowing is applied to reduce spectral line width, then chromatic aberration is reduced, but device complexity increases
Solution Approach 1:
The patent integrates the line narrowing function directly into the laser resonator by incorporating a line narrowing element (such as an etalon or grating) within the resonator structure. This merging of functions allows the laser device to simultaneously achieve spectral line narrowing and maintain resonance, reducing chromatic aberration while avoiding the need for separate line narrowing components that would increase device complexity.
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
Enables efficient estimation of optical pulse stretcher deterioration with reduced measurement time and the ability to predict future replacement needs, maintaining laser device performance.
Implementation Method 1
an optical pulse stretcher configured to extend a pulse width of pulse laser light
Data Source
AI summary
A deterioration estimation method of an optical pulse stretcher configured to extend a pulse width of pulse laser light includes acquiring a first temporal waveform, at a first measurement timing, of the pulse laser light having the pulse width extended by the optical pulse stretcher; acquiring a second temporal waveform, at a second measurement timing after the first measurement timing, of the pulse laser light having the pulse width extended by the optical pulse stretcher; and estimating a degree of deterioration of the optical pulse stretcher based on the first temporal waveform and the second temporal waveform.