Metrology System Using Optical Frequency Separation for Spectral Feature Estimation
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Solution Overview
Problem
Accurate measurement and control of spectral features, such as bandwidth, of light beams in lithography exposure systems are challenging due to disturbances like temperature and optical distortions, which affect the precision of feature size control in deep ultraviolet lithography.
Innovation Solution
A metrology system that includes an optical frequency separation apparatus and multiple sensing regions to measure and analyze the spectral components of a pulsed light beam, averaging the properties to estimate the spectral feature and adjust it if necessary, using a control system connected to a spectral feature selection system to maintain acceptable spectral characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single sensor is used to measure spectral features, then the device complexity is low, but the measurement precision deteriorates due to noise and disturbances
Solution Approach 1:
The patent divides the measurement task into multiple independent sensing regions (first sensing region, second sensing region, etc.), each measuring spectral components at different wavelengths. By segmenting the measurement process across multiple sensors and then combining the results through averaging, the system achieves higher measurement precision while managing complexity through modular design
Solution Approach 2:
The patent combines measurements from multiple sensing regions through averaging to produce a final spectral feature estimate. This merging of multiple independent measurements reduces the impact of noise and disturbances on any single sensor, thereby improving overall measurement precision
2Measurement precision
If multiple sensing regions are used to improve measurement precision, then the measurement precision improves, but the device complexity increases
Solution Approach 1:
The measurement system is segmented into multiple sensing regions, each responsible for measuring specific spectral components. This segmentation allows parallel measurement of different wavelength regions, improving precision through statistical averaging while maintaining manageable system complexity through clear functional division
Solution Approach 2:
Each sensing region is designed to measure spectral components at specific wavelengths, with the entire system serving the universal function of characterizing the pulsed light beam spectrum. The modular sensing regions can be configured to cover different wavelength ranges, providing versatility while improving measurement precision
3Manufacturing precision
If spectral features are not accurately controlled, then the manufacturing precision of feature size deteriorates, but the device complexity and control system requirements increase
Solution Approach 1:
The control system receives measurement data from the multiple sensing regions, compares the measured spectral features against target values, and generates adjustment signals to control the optical source. This feedback loop ensures accurate spectral feature control, which directly improves feature size manufacturing precision in lithography applications
Solution Approach 2:
The patent replaces complex mechanical adjustment mechanisms with an optical-based measurement and control system. By using optical frequency separation apparatus and photodetector arrays to measure spectral features, and controlling the optical source through electronic feedback, the system achieves precise feature size control without complex mechanical interventions
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 approach improves the precision of spectral feature measurement and control, reducing noise and maintaining precise spectral features, thereby enhancing the accuracy of feature size control in lithography processes.
Implementation Method 1
an optical frequency separation apparatus in the path of the pulsed light beam and configured to interact with the pulsed light beam and output a plurality of spatial components that correspond to the spectral components of the pulsed light beam
Implementation Method 2
a plurality of sensing regions that receive and sense the output spatial components
Data Source
AI summary
A metrology system includes an optical frequency separation apparatus in the path of the pulsed light beam and configured to interact with the pulsed light beam and output a plurality of spatial components that correspond to the spectral components of the pulsed light beam; a plurality of sensing regions that receive and sense the output spatial components; and a control system connected to an output of each sensing region. The control system is configured to: measure, for each sensing region output, a property of the output spatial components from the optical frequency separation apparatus for one or more pulses; analyze the measured properties including averaging the measured properties to calculate an estimate of the spectral feature of the pulsed light beam; and determine whether the estimated spectral feature of the pulsed light beam is within an acceptable range of values of spectral features.