Dual Beam Path Illumination Measuring Device
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Solution Overview
Problem
Existing measuring devices require significant time and space to calibrate illumination systems for precise measurement of intensity distribution in both the illumination plane and pupil, necessitating separate instruments and complex setups.
Innovation Solution
A compact measuring device with two-dimensional resolving intensity detectors and dual measurement beam paths that combine illumination uniformity and pupil measurement functions, using a single intensity detector and imaging optical unit to image the illumination field onto the detector, reducing spatial requirements and calibration effort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate measuring instruments are used for measuring illumination uniformity and pupil intensity distribution, then measurement accuracy is improved, but device complexity and spatial requirements increase
Solution Approach 1:
The patent combines two separate measuring instruments (illumination uniformity meter and pupil intensity distribution meter) into a single integrated measuring device. The device includes a first measuring unit for measuring illumination uniformity in the illumination plane and a second measuring unit for measuring pupil intensity distribution, both integrated within one device structure. This merging reduces device complexity and spatial requirements while maintaining measurement accuracy through dedicated measuring units for each function.
Solution Approach 2:
The measuring device is designed with multi-functionality to perform both illumination uniformity measurement and pupil intensity distribution measurement. The device can switch between different measurement modes: in the first measurement position, it measures illumination uniformity in the illumination plane; in the second measurement position, it measures pupil intensity distribution. This universal design eliminates the need for separate instruments while preserving measurement precision.
2Loss of time
If measuring instruments are integrated into the inspection apparatus, then calibration time is reduced, but spatial requirements within the apparatus increase
Solution Approach 1:
The patent integrates both measuring units into a single compact device that occupies reduced space within the inspection apparatus. The integrated device includes a first measuring unit and a second measuring unit sharing common structural elements, reducing the total spatial footprint compared to separate instruments while enabling rapid calibration through integrated design.
Solution Approach 2:
The measuring device utilizes angular positioning to switch between measurement functions. The device can be positioned at different angular positions relative to the illumination system: at a first angular position for measuring illumination uniformity in the illumination plane, and at a second angular position for measuring pupil intensity distribution. This angular dimensionality allows functional switching without requiring separate spatial volumes for each measurement type.
3Measurement precision
If individual calibration of measuring instruments is performed, then measurement accuracy is ensured, but calibration time and effort increase
Solution Approach 1:
The integrated measuring device allows for unified calibration procedures that calibrate both measuring units simultaneously or in sequence within a single calibration process. The device structure enables access to both the illumination plane and pupil plane through the same physical interface, eliminating the need for separate calibration setups and reducing total calibration time while maintaining accuracy through dedicated measuring units.
Solution Approach 2:
The universal measuring device performs multiple measurement functions through a single integrated system, allowing calibration to be performed once for the entire device rather than separately for each instrument. The device can switch between measuring illumination uniformity and pupil intensity distribution using the same physical interface and detector, streamlining the calibration process while ensuring measurement precision for both functions.
4Area of stationary object
If a single intensity detector is used for both measurement functions, then spatial requirements are reduced, but measurement precision may be compromised
Solution Approach 1:
The patent utilizes angular positioning to direct illumination radiation to the single intensity detector for different measurement functions. The device can be positioned at a first angular position where the illumination detector measures illumination uniformity in the illumination plane, and at a second angular position where the same detector measures pupil intensity distribution. This angular dimensionality allows a single detector to serve both functions without spatial conflict while maintaining measurement precision through proper optical path configuration.
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, time-saving measurements of illumination properties with improved accuracy and reduced spatial requirements, allowing integration into inspection apparatuses for EUV microlithography applications.
Implementation Method 1
an imaging optical unit (44) arranged in the first measurement beam path (52) such that the illumination radiation (20) guided in the first measurement beam path (52) passes through the imaging optical unit (44)
Data Source
AI summary
A measuring device (40) for measuring an illumination property of an illumination system (12), which is configured for two-dimensional irradiation of a substrate (24) arranged in an illumination plane (21) with illumination radiation (20). Two differing measurement beam paths (52, 54) are formed in the measuring device, each arranged to guide the illumination radiation emitted by the illumination system onto a spatially resolving intensity detector (42) of the measuring device. A first (52) of the measurement beam paths is arranged to measure an intensity distribution in the illumination plane and the second (54) of the measurement beam paths is arranged to measure an intensity distribution in a pupil of the illumination system. The measuring device also includes an imaging optical unit (44) arranged in the first measurement beam path (52) such that the illumination radiation guided in the first measurement beam path passes through the imaging optical unit.