Switchable Illumination Mode Selector for Cross-System Optical Metrology
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Solution Overview
Problem
Existing metrology tools struggle to match data across different systems due to phase-related differences, leading to inconsistencies in measurements, particularly in low-k1 lithography processes, where current methods like the Jones Framework fail to account for phase shifts.
Innovation Solution
An illumination mode selector and optical metrology tool with individually switchable illumination and detection apertures and polarization-changing elements, allowing for a generic framework to map intensity metrics across systems, using calibration data to align measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing metrology tools use conventional measurement configurations, then the device complexity is reduced, but the measurement precision and system-to-system data matching deteriorate due to inability to account for phase shifts
Solution Approach 1:
The illumination and detection paths are segmented into multiple independently switchable apertures and polarization-changing elements. This allows systematic variation of measurement configurations to capture phase shift information while maintaining manageable complexity through modular design
Solution Approach 2:
The system employs dynamically switchable apertures and polarization elements that can be individually activated based on measurement requirements. This dynamic reconfiguration enables the system to adapt to different phase conditions without requiring permanent complex hardware for all possible configurations
2Adaptability or versatility
If more measurement configurations are added to metrology tools, then the adaptability and data matching capability improve, but the device complexity increases
Solution Approach 1:
The patent implements a universal set of apertures and polarization-changing elements that can be combined in multiple configurations to achieve various measurement objectives. These components serve multiple functions: phase shift characterization, system calibration, and data matching across different metrology systems
Solution Approach 2:
The system performs preliminary calibration measurements using the configurable apertures and polarization elements to establish system-specific calibration data before actual metrology operations. This preliminary action enables subsequent measurements to be normalized across systems without requiring permanent complex configurations
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
Enhances system-to-system data matching by leveraging intensity metrics and calibration data, ensuring consistent and accurate measurements across various metrology tools.
Implementation Method 1
at least one polarization-changing optical element; wherein each of the illumination apertures and each of the at least one polarization-changing optical element are individually switchable into an illumination path of the optical metrology tool
Data Source
AI summary
An illumination mode selector for use in an illumination branch of an optical metrology tool, and an associated optical metrology tool. The illumination mode selector includes a plurality of illumination apertures; and at least one polarization-changing optical element. Each of the illumination apertures and each of the at least one polarization-changing optical element are individually switchable into an illumination path of the optical metrology tool.