Hyperspectral Imager for Multi-Wavelength Metrology
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Solution Overview
Problem
Conventional metrology apparatuses in lithographic processes can only perform measurements using a single wavelength of measurement radiation, which limits their ability to accurately measure targets in different layers due to varying behavior across different wavelengths, requiring individual tuning for each layer and reducing measurement efficiency.
Innovation Solution
A metrology apparatus equipped with an illumination system providing measurement radiation comprising multiple wavelengths and a hyperspectral imager that captures a hyperspectral representation of the structure by spatially modulating and spectrally dispersing the scattered radiation, enabling the estimation of a three-dimensional data cube from a two-dimensional coded spatio-spectral projection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional scatterometers use single wavelength measurement radiation, then the device complexity is reduced and operation is simplified, but measurement precision and reliability deteriorate due to inability to optimize wavelength for different layers
Solution Approach 1:
The patent applies parameter changes by transitioning from single-wavelength to multi-wavelength measurement radiation. The illumination system is configured to provide measurement radiation comprising multiple wavelengths, allowing optimization of wavelength selection for different layers and targets. This enables improved measurement precision while managing device complexity through systematic parameter variation.
Solution Approach 2:
The hyperspectral imager provides multi-functionality by capturing scattered radiation across multiple wavelengths simultaneously. This single device performs what would otherwise require multiple separate measurement systems, achieving universal measurement capability across different layers and target types while maintaining operational simplicity.
2Measurement precision
If individual wavelength tuning is performed for each layer, then measurement precision is improved, but productivity decreases due to time-consuming sequential measurements
Solution Approach 1:
The patent implements continuity of useful action by performing multi-wavelength measurements simultaneously in a single continuous operation. The hyperspectral imager captures scattered radiation across the entire wavelength range in one measurement cycle, eliminating the need for sequential wavelength tuning and maintaining continuous productive action.
Solution Approach 2:
Multiple wavelength measurements that would traditionally be performed separately are merged into a single simultaneous measurement operation. The illumination system provides multiple wavelengths and the hyperspectral imager captures them all at once, combining what would be multiple discrete measurement actions into one unified operation.
3Adaptability or versatility
If multi-wavelength measurement is implemented, then measurement precision and versatility are improved, but device complexity increases due to need for hyperspectral imaging system
Solution Approach 1:
The hyperspectral imager serves as a universal measurement device that handles multiple wavelengths and different target types with a single system. This multi-functional approach achieves high adaptability while avoiding the need for multiple specialized devices, thereby managing overall system complexity.
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 allows for simultaneous measurement with multiple wavelengths, optimizing the wavelength selection for each layer and enhancing the robustness of overlay measurements, thereby improving measurement accuracy and throughput by reducing the need for individual tuning and increasing the ability to handle multilayer targets.
Implementation Method 1
measure one or more properties of the scattered radiation—e.g., intensity at a single angle of reflection as a function of wavelength
Implementation Method 2
spectrally dispersing the scattered measurement radiation to obtain a two-dimensional coded spatio-spectral projection
Data Source
AI summary
Disclosed is a metrology apparatus and method for measuring a structure formed on a substrate by a lithographic process. The metrology apparatus comprises an illumination system operable to provide measurement radiation comprising a plurality of wavelengths; and a hyperspectral imager operable to obtain a hyperspectral representation of a measurement scene comprising the structure, or a part thereof, from scattered measurement radiation subsequent to the measurement radiation being scattered by the structure.