Optical Module Calibration Using Dynamic Excitation Profile Fitting
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Solution Overview
Problem
Existing methods for calibrating manipulable optical modules in microlithographic projection exposure apparatuses suffer from inaccuracies and inefficiencies, particularly due to deviations between the actual and specified variation profiles, leading to suboptimal imaging of mask structures on wafers.
Innovation Solution
A method involving a temporally varying excitation signal applied to manipulation elements, followed by data processing to estimate and fit a temporally varying scaling, allowing for the determination of a full effect profile and calibration data to accurately set the variation profile, thereby suppressing static and dynamic errors without significantly extending measurement time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If regular aberration measurement and simulation-based actuation signal determination are used, then the calibration process is simple and quick, but deviations between actual and specified variation profiles occur, reducing imaging accuracy
Solution Approach 1:
The patent applies periodic excitation signals to the manipulation elements during calibration, enabling the system to capture dynamic response characteristics. This periodic action allows for more accurate determination of the full effect profile by measuring the system's response at multiple time points, thereby improving calibration accuracy without requiring excessive measurement time.
Solution Approach 2:
The patent implements a feedback mechanism where the measured variation profiles from periodic excitation are used to iteratively refine the full effect profile. The system continuously compares actual measurements with simulated responses and adjusts the calibration data accordingly, ensuring high accuracy while maintaining efficient measurement processes.
2Measurement precision
If static error suppression methods are applied, then measurement accuracy improves, but measurement time increases significantly
Solution Approach 1:
The patent performs preliminary characterization of the manipulation elements' dynamic response through periodic excitation before actual calibration. By pre-determining the full effect profile including dynamic characteristics, the system suppresses both static and dynamic errors in advance, eliminating the need for time-consuming error correction during the calibration process itself.
Solution Approach 2:
The patent changes the excitation parameters (amplitude, frequency, timing) to optimize the measurement process. By carefully selecting excitation signal characteristics, the system achieves comprehensive error suppression while maintaining short measurement times, balancing accuracy and productivity.
Data Source
AI summary
A method for calibrating a manipulable optical module for a microlithographic projection exposure apparatus, which comprises at least one manipulation element for setting an at least one-dimensional local variation profile of an optical property of the optical module is provided. The method comprises: applying a temporally varying excitation signal to the at least one manipulation element; determining a raw measurement data set via a measurement device measuring the respective local variation profile resulting at different times during the variation of the excitation signal; estimating a temporally varying scaling, caused by the temporal variation of the excitation signal, in the variation profiles of the raw measurement data set; determining a full effect profile of the optical property by fitting the temporally varying scaling to the variation profiles of the raw measurement data set; and determining calibration data of the manipulable optical module on the basis of the full effect profile.