Raman Spectroscopy Sub-20 nm Metrology via Quantum Confinement
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Solution Overview
Problem
Current scatterometers are limited in resolving power, struggling to characterize dimensional features below 20 nm, and contact-based methods like SEM and AFM are too slow and costly for routine inspection in mass production.
Innovation Solution
A method using Raman spectroscopy to measure dimensional characteristics by analyzing the shift and broadening of spectral components caused by quantum confinement effects in inelastic scattering, employing a calibration structure to estimate the dimensions of target structures, and an apparatus comprising illumination and detection optics with a processor for calculating these characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If scatterometry is used for measuring dimensional characteristics, then measurement speed is high and it is non-contact, but measurement precision deteriorates for features below 20 nm
Solution Approach 1:
The patent changes the physical parameter being measured from elastic scattering (conventional scatterometry) to inelastic scattering (Raman spectroscopy). This parameter change enables the measurement system to access quantum confinement effects that occur at dimensions below 20 nm, thereby improving measurement precision for nanoscale features while maintaining the high-speed non-contact nature of scatterometry
Solution Approach 2:
The patent replaces the conventional optical measurement approach (elastic scattering) with a quantum-mechanical approach (inelastic scattering involving phonon interactions). This substitution enables the system to probe dimensional characteristics at the quantum level, achieving precision for sub-20 nm features that classical optics cannot resolve
2Measurement precision
If contact-based methods like SEM and AFM are used, then measurement precision improves for sub-20 nm features, but productivity deteriorates due to slow speed and high cost
Solution Approach 1:
The patent replaces contact-based mechanical measurement methods (SEM, AFM) with a non-contact optical method based on inelastic scattering. This substitution eliminates the mechanical contact requirement while achieving comparable or superior precision for sub-20 nm features, thereby restoring high measurement speed and reducing operational cost
Solution Approach 2:
The patent changes the measurement parameter from direct geometric imaging (contact methods) to quantum confinement effect analysis via inelastic scattering (Raman spectroscopy). This parameter change enables non-contact measurement while maintaining precision for nanoscale dimensional characteristics
Data Source
AI summary
A substrate is provided with device structures and metrology structures (800). The device structures include materials exhibiting inelastic scattering of excitation radiation of one or more wavelengths. The device structures include structures small enough in one or more dimensions that the characteristics of the inelastic scattering are influenced significantly by quantum confinement. The metrology structures (800) include device-like structures (800b) similar in composition and dimensions to the device features, and calibration structures (800a). The calibration structures are similar to the device features in composition but different in at least one dimension. Using an inspection apparatus and method implementing Raman spectroscopy, the dimensions of the device-like structures can be measured by comparing spectral features of radiation scattered inelastically from the device-like structure and the calibration structure.