Multi-Aperture Substrate Illumination Beam Calibration
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Solution Overview
Problem
Current methods for measuring illumination beam characteristics are time-consuming and impractical for on-site calibration, particularly in modern metrology systems where illumination source components deteriorate or move, requiring frequent recalibration to maintain beam quality.
Innovation Solution
A system and method utilizing a substrate with spatially distributed apertures that are actuated through an illumination beam, allowing for the comparison of intensity levels at different offsets and focus levels to determine and calibrate illumination beam characteristics, such as minimum beam spot size and location, and compensate for changes over time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If current methods for measuring illumination beam characteristics are used, then measurement accuracy can be achieved, but calibration time becomes excessively long and impractical for on-site calibration
Solution Approach 1:
The substrate is segmented into multiple discrete apertures arranged in a grid pattern, allowing simultaneous measurement at multiple spatial locations. This segmentation enables parallel data collection across the beam profile, reducing the time required to map the entire illumination pattern while maintaining measurement accuracy through multiple sampling points.
Solution Approach 2:
The system uses a finite array of discrete apertures rather than continuous scanning, sampling the illumination beam at sufficient points to characterize the beam profile accurately. This partial action approach captures the essential beam characteristics without requiring exhaustive measurement of every possible location, significantly reducing calibration time while maintaining practical accuracy.
2Reliability
If illumination source components deteriorate or move over time, then beam characteristics change requiring recalibration, but frequent recalibration increases maintenance time and reduces productivity
Solution Approach 1:
The system performs preliminary characterization of the illumination beam profile using the multi-aperture substrate before actual metrology measurements. By pre-mapping the beam characteristics including minimum beam spot location and size, the system establishes baseline data that can be used to compensate for subsequent drift, reducing the frequency and impact of full recalibration events.
Solution Approach 2:
The system continuously monitors beam characteristics through the aperture array and provides feedback on deviations from the minimum beam spot. This feedback mechanism enables real-time detection of illumination source deterioration or movement, allowing for targeted recalibration only when necessary, thus maintaining beam quality while minimizing interruptions to productivity.
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 and practical on-site calibration of illumination sources by accurately determining and compensating for changes in beam characteristics, improving metrology system performance and reducing calibration time.
Implementation Method 1
A detector may be configured to receive at least a portion of illumination passing through at least one aperture of the plurality of apertures
Data Source
AI summary
The disclosure is directed to a system and method for determining at least one characteristic of an illumination beam emanating from an illumination source. A substrate having a plurality of apertures may be actuated through an illumination beam so that apertures at different spatial offsets are scanned through the illumination beam at one or more levels of focus. Portions of illumination directed through scanned apertures may be received by at least one detector. At least one characteristic of the illumination beam may be extracted from data points associated with intensity levels associated with detected portions of illumination. Furthermore, multiple determinations of a beam characteristic made over a period of time may be utilized to calibrate the illumination source.