Multi-Wavelength Illumination Metrology for Lithography
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Solution Overview
Problem
Current metrology systems face challenges in quickly and accurately measuring a large number of lithographic features, particularly as ICs become smaller and more densely packed, requiring improved capabilities to keep pace with high-volume manufacturing rates and production speeds.
Innovation Solution
The implementation of an illumination system with first and second sources generating different wavelength bands, optically coupled to respective resonators that narrow these bands, and a detector to generate measurement signals based on radiation from a target structure, allowing for efficient and precise measurement of substrate parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional optical scatterometers are used to measure lithographic features, then measurement capability is provided, but the system cannot quickly and accurately measure a large number of features due to limited measurement speed and capacity
Solution Approach 1:
The illumination system is segmented into multiple independent sources (first source, second source, third source) each operating at different wavelengths. Each source can be independently controlled and optimized for specific measurement tasks, enabling parallel processing of multiple measurement functions simultaneously to increase overall measurement throughput while maintaining precision through wavelength-specific optimization
Solution Approach 2:
The metrology system is designed with multi-functionality by incorporating multiple illumination sources that can measure different substrate parameters (overlay error, critical dimension, focus, etc.) using a single integrated platform. The system can switch between different wavelength bands and measurement modes to handle various measurement requirements, effectively increasing measurement capacity without requiring separate dedicated instruments for each parameter
2Productivity
If the number of measurement features is increased to keep pace with IC density, then manufacturing capability is improved, but the complexity of measuring all features accurately increases
Solution Approach 1:
The measurement system segments the illumination function into multiple wavelength bands (first wavelength band, second wavelength band, third wavelength band) generated by separate sources. This segmentation allows the system to address different measurement requirements simultaneously using appropriate wavelength-specific sources, enabling measurement of multiple features at different locations on the substrate without requiring a single overly complex monolithic system
Solution Approach 2:
The system adds the wavelength dimension to the measurement capability by introducing multiple illumination sources at different wavelengths. This dimensional addition allows the system to encode different measurement types and target features in the spectral domain, enabling parallel measurement of multiple features without increasing spatial complexity of the measurement apparatus
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 faster and more accurate measurement of lithographic features, enhancing the capability to handle increased complexity and density in IC manufacturing by increasing the number of simultaneous measurements and measurement speed.
Implementation Method 1
first and second resonators optically coupled to respective ones of the first and second sources and configured to narrow respective ones of the first and second wavelength bands
Implementation Method 2
a detector configured to receive radiation returning from the target structure and to generate a measurement signal based on the received radiation
Data Source
AI summary
A system includes an illumination system, an optical element, and a detector. The optical system is implemented on a substrate. The illumination system includes first and second sources and first and second generators. The illumination system generates a beam of radiation. The first and second sources generate respective first and second different wavelength bands. The first and second resonators are optically coupled to respective ones of the first and second sources and narrow respective ones of the first and second wavelength bands. The optical element directs the beam toward a target structure. The detector receives radiation from the target structure and to generate a measurement signal based on the received radiation.