Multilayer Substrate Metrology for Sub-Wavelength Critical Dimensions
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Solution Overview
Problem
Conventional imaging and metrological methods are inadequate for accurately measuring multilayered substrates with critical dimensions due to limitations in resolution and complexity, particularly in the semiconductor industry, where structures with critical dimensions below the optical wavelength are challenging to characterize without damaging the substrate.
Innovation Solution
A method and device utilizing a combination of measurement technologies such as VUV/UV/VIS/NIR variable angle spectral ellipsometry, IR variable angle spectral ellipsometry, polarized reflectometry, scatterometry, and spectroscopy, along with rigorous coupled-wave analysis (RCWA) for simulation, to characterize multilayered substrates with critical dimensions, enabling high-accuracy measurement of optical properties and structural parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional imaging methods such as optical microscopy are used to measure structures with critical dimensions, then the measurement process is simple and non-destructive, but the resolution is limited to structural dimensions above half the optical wavelength due to the Abbe resolution limit
Solution Approach 1:
The patent replaces conventional optical imaging methods with scatterometric measurement methods that do not rely on mechanical resolution limits. By measuring scattered light patterns and analyzing them through rigorous coupled-wave analysis, the system achieves sub-wavelength resolution without requiring mechanical improvements to the imaging system.
Solution Approach 2:
The patent changes the measurement parameter from direct spatial resolution to optical scattering pattern analysis. By measuring intensity distributions of scattered light at different angles and wavelengths, and analyzing these patterns through computational methods, the system extracts dimensional information beyond the optical resolution limit.
2Measurement precision
If transmission electron microscopy, scanning electron microscopy, or atomic force microscopy are used to measure structures with critical dimensions, then the resolution is sufficient for sub-wavelength structures, but the measurement process is too time-intensive for process monitoring and series production
Solution Approach 1:
The patent replaces slow, time-consuming electron microscopy and atomic force microscopy with optical scatterometric measurements. By using light scattering and computational analysis, the system achieves comparable or superior resolution while dramatically improving measurement speed and throughput for industrial production environments.
Solution Approach 2:
The patent creates an optical scattering pattern 'copy' of the structure's dimensional information. Instead of directly imaging the structure (which is slow), the system measures the scattered light pattern and computationally reconstructs the structural parameters, enabling rapid analysis suitable for process monitoring.
3Measurement precision
If conventional imaging methods are combined with non-imaging optical scatterometric measuring methods, then the measurement capability is enhanced, but the complexity of the measurement system increases
Solution Approach 1:
The patent merges conventional optical imaging capabilities with scatterometric measurement methods into a unified optical measurement system. By combining these approaches, the system leverages the strengths of both methods to achieve comprehensive characterization of multilayered substrates with critical dimensions while maintaining a single optical platform.
Solution Approach 2:
The patent develops an optical measurement system that performs multiple functions: it can measure layer thicknesses, critical dimensions, and optical properties using the same optical platform and scatterometric principles. This multi-functionality reduces the need for separate specialized instruments and simplifies the overall measurement system.
4Object-affected harmful factors
If spectroscopic ellipsometry and reflectometry are used to measure layer thicknesses and optical material properties, then the measurement process is non-destructive and suitable for process control, but the measurement of complex multilayered substrates with structures becomes difficult
Solution Approach 1:
The patent extends optical scatterometry to handle complex multilayered substrates with structures. By analyzing scattered light patterns from these complex structures and using rigorous coupled-wave analysis, the system extracts both layer thicknesses and structural critical dimensions non-destructively, overcoming the limitations of conventional ellipsometry for structured surfaces.
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 characterization of multilayered substrates with complex structures by simultaneously reconstructing layer and structure parameters, providing high accuracy and computational efficiency in process monitoring.
Implementation Method 1
Classic ellipsometry is used in the prior art in order to measure layer thicknesses and optical material properties, such as refractive index and reflectance
Implementation Method 2
measuring the substrate, and in particular the structure, using at least one measuring technology
Implementation Method 3
polarized reflectometry, scatterometry, and spectroscopy, along with rigorous coupled-wave analysis (RCWA) for simulation
Data Source
AI summary
A method for measuring a multilayered substrate, particularly with at least one structure with critical dimensions, the method including the steps of (a) producing the substrate with a plurality of layers, particularly with a structure, wherein the dimensions of the layers and in particular the structures are known, (b) measuring the substrate using at least one measuring technology, (c) creating a simulation of the substrate using the measurement results from the measurement of the substrate, (d) comparing the measurement results with simulation results from the simulation of the substrate, and (e1) optimizing the simulation and renewed creation of a simulation of the substrate using the measurement results from the measurement of the substrate, in the event that there is a deviation of the measurement results from the simulation results, or (e2) calculating parameters of further substrates, in the event that the measurement results correspond to the simulation results.