Short-Wavelength Metrology with Segmented EUV Source Control
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Solution Overview
Problem
Current metrology techniques struggle to accurately measure small features on substrates due to the limitations of available radiation wavelengths, leading to inaccurate measurements and the inability to penetrate through thick process layers, and existing high-frequency radiation sources are either too large or too expensive for high-volume manufacturing.
Innovation Solution
A method and apparatus that utilize a generation medium to generate measurement radiation by simultaneously providing first and second radiation to specific subregions, either suppressing or enhancing measurement radiation, allowing for the capture of scattered radiation to improve measurement precision and reduce beam size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If visible or near-infrared radiation is used for metrology, then the grating pitch must be much coarser than actual product structures, but this results in inability to measure small features accurately
Solution Approach 1:
The patent changes the wavelength parameter of the radiation from visible/near-infrared to extreme ultraviolet (EUV) range (10-20 nm). This parameter change allows the grating pitch to be reduced to match actual product structures while maintaining measurement capability, thereby enabling accurate measurement of small features that were previously unmeasurable with longer wavelengths
2Measurement precision
If EUV radiation with wavelength 10-20 nm is used, then small features can be measured accurately, but the radiation source must be very small to achieve sufficient brilliance
Solution Approach 1:
The patent segments the source region into multiple independent laser spots that can be selectively activated. By using a segmented approach with multiple small spots rather than a single large source, the system achieves the required small effective source size for high brilliance while maintaining flexibility in source configuration and management
Solution Approach 2:
The patent implements dynamic control of the laser spots through independent activation and positioning. The source configuration can be dynamically adjusted by selecting which spots are active and their spatial arrangement, allowing optimization of source size and brilliance based on measurement requirements
3Power
If multiple laser spots are used to generate EUV radiation, then source brilliance can be increased, but system complexity increases
Solution Approach 1:
The patent implements self-service through automated spot management where the system automatically handles the coordination and control of multiple laser spots. The control system autonomously manages spot activation, positioning, and timing without requiring complex manual intervention, thereby reducing operational complexity while maintaining high source brilliance
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 precise measurement of small features with reduced crosstalk from neighboring structures, using high-frequency radiation to penetrate deeper into the substrate, thereby improving measurement accuracy and efficiency.
Implementation Method 1
providing, simultaneously with the provision of first radiation at the first region, either second radiation to at least a first subregion of the first region so as to suppress generation of the measurement radiation within the first subregion or second radiation to at least a second subregion of the first region to enhance generation of the measurement radiation within the second subregion
Data Source
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AI summary
Disclosed is a method of and apparatus for metrology or inspection of a structure on a substrate. The method comprises providing first radiation to a first region of a generation medium to generate measurement radiation; providing, simultaneously with the provision of first radiation at the first region, either second radiation to at least a first subregion of the first region so as to suppress generation of the measurement radiation within the first subregion or second radiation to at least a second subregion of the first region to enhance generation of the measurement radiation within the second subregion; illuminating the structure with the measurement radiation; and capturing scattered radiation, having scattered from the structure as a result of the illuminating step.