Pupil Stop Shape Optimization for Optical Metrology Simulation
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Solution Overview
Problem
Metrology systems struggle to accurately simulate the illumination and imaging properties of optical production systems due to differences in design and energy setup, leading to deviations in simulation results.
Innovation Solution
An optimization method for pupil stop shape is developed using mathematical modeling to determine the effects of stop shape changes on illumination and imaging properties, allowing for precise simulation of optical production systems' properties during object illumination and imaging, accounting for complex settings and structural specifications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the metrology system uses the same design and energy setup as the optical production system, then the simulation accuracy of illumination and imaging properties is improved, but the device complexity and cost increase significantly
Solution Approach 1:
The patent creates a simplified copy of the production system's optical properties through mathematical modeling. Instead of physically replicating the complex production system, the invention models its illumination and imaging properties computationally, allowing accurate simulation without the associated complexity and cost.
Solution Approach 2:
The invention changes the approach from physical replication to parameter-based simulation. By modeling optical properties as adjustable parameters in a computational framework, the system achieves accurate simulation of illumination and imaging characteristics without requiring identical physical configurations.
2Measurement precision
If the pupil stop shape is modified to improve simulation accuracy, then the match quality between metrology and production systems is improved, but the fabrication difficulty increases
Solution Approach 1:
Instead of physically modifying the pupil stop to match complex production system configurations, the invention creates a simplified computational model that replicates the optical effects. This allows accurate simulation of complex illumination settings without the fabrication difficulty of creating physically complex stop shapes.
Solution Approach 2:
The patent replaces physical mechanical modifications to the pupil stop with computational modeling. Rather than fabricating complex stop shapes to achieve desired optical properties, the invention uses software-based optical modeling to simulate the effects, eliminating fabrication difficulties while maintaining accuracy.
3Measurement precision
If the metrology system is designed with high energy output to match production system capabilities, then the simulation fidelity is improved, but the energy consumption and system cost increase
Solution Approach 1:
The invention creates a computational copy of the production system's optical behavior rather than a physical copy requiring equivalent energy resources. The mathematical model simulates illumination and imaging properties without requiring the metrology system to consume production-level energy.
Solution Approach 2:
The patent substitutes physical energy-intensive optical processes with computational modeling. Instead of requiring the metrology system to consume high energy to match production system capabilities, the invention uses software-based simulations that achieve the same measurement objectives with minimal energy consumption.
Data Source
AI summary
In order to simulate properties of an optical production system, use is made of an optical measurement system comprising an illumination optical unit for an object to be imaged having a pupil stop in the region of an illumination pupil and an imaging optical unit for imaging the object. In order to optimize a pupil stop shape of the pupil stop, firstly a starting stop shape of the pupil stop is predefined as an initial design candidate for the simulation. The starting stop shape is modified and at least one fabrication boundary condition of the corresponding modification stop shape is checked. The steps “modifying” and “checking” are repeated until the checking reveals compliance with the boundary conditions. A match quality between the properties of the optical production system and those of the optical measurement system is determined and the steps “modifying”, “checking” and “determining” are repeated until the match quality attains a predefined optimization criterion, which is queried. A target stop shape resulting from the target stop shape that occurred with the smallest merit function value E in the optimization is fabricated as an optimized pupil stop shape after attaining the optimization criterion. This results in simulation—as free of deviations as possible—of the illumination and imaging properties of the optical production system during the illumination and imaging of the object by use of the optical measurement system.