Segmented Optical Detector with Spatially Separated Coatings
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Solution Overview
Problem
Current optical detectors for measuring small features in lithographic processes face limitations due to the absorption of short-wavelength radiation by air and the need for freestanding ultrathin metal films, which result in significant radiation loss and restricted wavelength range.
Innovation Solution
The use of a detector with spatially separated coatings, such as Zr and Al, to filter and transmit radiation within specific wavelength ranges, allowing for the detection of radiation over a broader frequency band without interference from higher diffraction orders, thereby avoiding the need for freestanding metal films.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If freestanding ultrathin metal films are used to filter radiation, then radiation loss is significant, but wavelength range is restricted
Solution Approach 1:
The detector surface is segmented into multiple regions, each coated with different materials having different transmission characteristics. This allows simultaneous transmission of multiple wavelength ranges without requiring a single ultrathin film that would transmit all wavelengths equally, thus reducing radiation loss while maintaining broad wavelength range.
Solution Approach 2:
Different regions of the detector have locally optimized coatings tailored to specific wavelength ranges. Each region's coating is optimized for its specific function, allowing the overall detector to handle a broad wavelength range while each local region minimizes radiation loss for its designated wavelengths.
2Adaptability or versatility
If a single coating is used to transmit all wavelengths, then wavelength range is broad, but diffraction orders overlap
Solution Approach 1:
The detector is divided into multiple regions that spatially separate different wavelength ranges. This segmentation prevents overlap of diffraction orders by directing different wavelengths to different detector regions, maintaining measurement precision while preserving broad wavelength range capability.
Solution Approach 2:
Each detector region has specialized coatings optimized for specific wavelength ranges. This local optimization ensures that each region clearly distinguishes its designated wavelengths from others, preventing diffraction order overlap while maintaining comprehensive wavelength coverage across all regions.
3Measurement precision
If shorter wavelength radiation is used to measure smaller features, then measurement capability improves, but radiation absorption by air increases
Solution Approach 1:
The system operates in a vacuum environment that replaces air with an inert medium. This eliminates absorption of short-wavelength radiation by air molecules, enabling the use of shorter wavelengths for measuring smaller features without signal loss.
4Adaptability or versatility
If broadband radiation is used to cover all wavelengths, then wavelength range is broad, but diffraction order overlap occurs
Solution Approach 1:
The broadband radiation detection is segmented across multiple detector regions, each responsible for a specific wavelength subset. This spatial segmentation preserves all wavelength information while preventing diffraction order overlap by directing different wavelength components to separate regions.
Solution Approach 2:
Each detector region has locally optimized coatings that selectively transmit specific wavelength ranges while blocking others. This local specialization maintains broad overall wavelength coverage while ensuring clean separation of diffraction orders within each region.
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 approach enables the detection of radiation over a larger wavelength range (6-50 nm) with reduced overlap of diffraction orders, improving measurement accuracy and reducing radiation loss, allowing for the measurement of smaller structures in lithographic processes.
Implementation Method 1
a first coating (304) configured to allow transmission of radiation with wavelengths within a first range of wavelengths
Implementation Method 2
a second coating (306) configured to allow transmission of radiation with wavelengths within a second range of wavelengths
Implementation Method 3
diffracted radiation which has been diffracted by a regular structure
Data Source
AI summary
A detector for detecting diffracted radiation which has been diffracted by a regular structure; said detector comprises: a sensor for sensing at least a portion of said diffracted radiation, said sensor having a first region and a second region; a first coating configured to allow transmission of radiation with wavelengths within a first range of wavelengths; and a second coating configured to allow transmission of radiation with wavelengths within a second range of wavelengths; wherein said first coating coats said first region of said sensor, and said second coating coats said second region of said sensor, and wherein said first and second regions are different regions.