Optical Assembly Contactless Temperature Monitoring
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Solution Overview
Problem
Current lithography systems face challenges in precisely determining the properties and alignment of optical elements, particularly in EUV projection systems, due to limitations in sensor placement, contamination detection, and aberration correction, which affect the accuracy and efficiency of imaging processes.
Innovation Solution
An optical assembly with an acquisition device that acquires radiation signals from marking elements outside the optically active regions of optical elements, allowing for spatially and temporally resolved determination of properties such as temperature, position, and alignment without additional sensors on the elements, enabling precise alignment and monitoring of optical elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If cable-based temperature sensors are mounted on the mirror rear side for monitoring optical properties, then spatial resolution of temperature monitoring is improved, but the cables produce dynamic short circuits between the mirror and apparatus frame
Solution Approach 1:
The patent removes cables from the optical path by using contactless temperature sensing. Infrared cameras or other non-contact sensors are positioned to monitor the mirror surface temperature without physical connection, eliminating the cable-induced short circuit problem while maintaining temperature monitoring capability.
Solution Approach 2:
The patent introduces an intermediary sensing mechanism (infrared camera or contactless sensor) that can detect temperature through radiation or optical means without direct contact with the mirror. This intermediary allows temperature monitoring while avoiding the harmful electrical connection between the mirror and apparatus frame.
2Measurement precision
If a large number of temperature sensors are mounted on or within the optical element to achieve high spatial resolution, then monitoring precision is improved, but manufacturing complexity and failure risk increase
Solution Approach 1:
The patent extracts the sensing function from the optical element itself by using external contactless sensors. Instead of embedding multiple sensors within or on the optical element, a single or few external infrared cameras or sensors monitor the entire surface, reducing manufacturing complexity while maintaining monitoring capability.
Solution Approach 2:
The patent creates an optical copy or image of the temperature distribution through infrared radiation detection. Rather than directly measuring temperature at multiple points with physical sensors, the system captures thermal radiation patterns that represent temperature distribution, simplifying the sensing architecture.
3Manufacturing precision
If multiple optical elements are used in the projection system to achieve precise imaging, then imaging precision is improved, but alignment complexity increases
Solution Approach 1:
The patent implements feedback mechanisms using sensors to detect the position and alignment status of optical elements. The system continuously monitors alignment parameters and provides feedback signals to actuators that automatically adjust element positions, reducing manual alignment complexity while maintaining high imaging precision.
Solution Approach 2:
The patent transitions from static mechanical alignment to dynamic alignment control. Optical elements are mounted on adjustable stages with real-time position monitoring and active correction capabilities, allowing the system to adapt to thermal drift and other variations during operation.
4Reliability
If optical elements are monitored during operation to detect variations in optical properties, then detection capability is improved, but the monitoring system adds complexity to the optical assembly
Solution Approach 1:
The patent designs the monitoring system to serve multiple functions: temperature monitoring, alignment verification, and optical property detection all use the same contactless sensing infrastructure. This multi-functional approach reduces overall system complexity compared to dedicated separate monitoring systems for each function.
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 solution enables efficient and precise determination of optical element properties, improving the accuracy of imaging processes, reducing contamination-related issues, and allowing for early detection of degradation, thereby enhancing the overall performance and reliability of lithography systems.
Implementation Method 1
an acquisition device (110) which is designed to acquire radiation signals from marking elements (414, 424) on or at the at least two optical elements (101, 103, 704, 705)
Data Source
AI summary
An optical assembly, in particular for a lithography system for imaging lithographic micro- or nanostructures, includes at least two optical elements arranged successively in a beam path of the optical assembly, an acquisition device designed to acquire radiation signals from marking elements on or at the at least two optical elements, and a control device coupled to the acquisition device and which is designed to determine the plurality of properties of the optically active surface of the at least two optical elements as a function of the information contained in the radiation signals originating from the marking elements. The disclosure also relates to a method for operating the optical assembly.