Assigning Pupil Facets to Field Mirrors in Projection Exposure
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Solution Overview
Problem
The challenge in projection exposure apparatuses is to reproducibly assign pupil facets to field facets for defining illumination channels, given the vast number of possibilities that scale with the number of facets, leading to inefficiencies in illumination optimization.
Innovation Solution
A method that determines illumination parameters based on design, individual-part, total-system, calibration, and online measurement data to define an evaluation function for optimizing the assignment of pupil facets to field facets, allowing for flexible adaptation to specific illumination tasks by incorporating weighting terms and predefining evaluation target ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the number of facets of the facet mirrors is increased to improve illumination quality, then the number of assignment possibilities scales with N! and becomes vast in magnitude, but this leads to difficulty in reproducing and selecting an optimal assignment
Solution Approach 1:
The patent applies parameter changes by transforming the combinatorial assignment problem into a parameter optimization problem. Instead of dealing with N! discrete assignments, the method uses continuous parameters (illumination parameters) to characterize and compare different assignments, enabling reproducible selection through parameter-based evaluation rather than exhaustive combinatorial search
Solution Approach 2:
The patent replaces the mechanical/manual process of assignment selection with an automated computational system. The evaluation function and automated selection process substitute for manual trial-and-error methods, using computer-based calculations to determine optimal assignments based on illumination parameters and measured data
2Reliability
If an automated assignment method is implemented to improve reproducibility, then selection consistency is improved, but the need for multiple determining steps (b) to (f) increases system complexity
Solution Approach 1:
The patent applies universality by creating a multi-functional evaluation framework that can handle multiple types of input data (design predefinition data, individual-part acceptance data, total-system acceptance data, calibration data, and online measurement data) through a single unified evaluation function. This allows the same method to work across different stages of system operation and different data sources
Solution Approach 2:
The patent applies preliminary action by predefining the evaluation function and evaluation target range before the actual assignment selection process. This preparatory step establishes the criteria for optimal assignments in advance, allowing the system to efficiently evaluate and select assignments based on pre-established parameters rather than determining all criteria during the selection process itself
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 method enables a reproducible and optimized selection of illumination channels, ensuring stable and efficient illumination settings by considering various data sets and adapting to the current state of the projection exposure apparatus, thereby improving the quality and handling of illumination.
Implementation Method 1
a partial beam of illumination light, which, proceeding from a light source, is reflected at the field facet and at the pupil facet assigned via the method toward an object field illuminated by the illumination optical unit
Data Source
AI summary
Methods are disclosed for assigning a pupil facet of a pupil facet mirror of an illumination optical unit of a projection exposure apparatus to a field facet of a field facet mirror of the illumination optical unit for the definition of an illumination channel for a partial beam of illumination light.