Layer-Specific Metrology Illumination for Multi-Layer Precision
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Solution Overview
Problem
Metrology systems face challenges in achieving consistent precision and repeatability when measuring multi-layer samples due to variations in layer-specific optical properties and configurations, leading to suboptimal image quality and metrology performance.
Innovation Solution
A metrology system with a controller that determines and applies layer-specific imaging configurations, including tailored illumination spectra, polarization, and sample positioning, to ensure accurate imaging and measurement of features across multiple sample layers within selected image quality tolerances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single imaging configuration is used for all sample layers, then the device complexity is reduced, but the measurement precision deteriorates due to varying optical properties across layers
Solution Approach 1:
The patent segments the imaging process by creating layer-specific imaging configurations for different sample layers. Each configuration is optimized for the optical properties of its target layer, allowing precise measurements without requiring a completely separate imaging system for each layer.
Solution Approach 2:
The patent implements dynamic switching between different imaging configurations based on which layer is being measured. The system can adaptively change illumination spectra, polarization states, and optical settings according to the specific layer requirements, maintaining precision while using a single versatile imaging system.
2Measurement precision
If layer-specific imaging configurations are implemented, then the measurement precision improves, but the ease of operation deteriorates due to multiple configuration parameters
Solution Approach 1:
The controller automatically selects and applies the appropriate imaging configuration based on the target layer being measured. This self-service approach eliminates the need for manual configuration by the operator, maintaining ease of operation while achieving layer-optimized measurement precision.
Solution Approach 2:
The system manages multiple configuration parameters (illumination spectra, polarization, optical settings) through centralized control that automatically adjusts these parameters based on the measurement requirements, simplifying the operator's task while maintaining precision.
3Measurement precision
If the illumination spectrum is tailored for each layer, then the measurement precision improves, but the use of energy increases due to multiple spectrum adjustments
Solution Approach 1:
The illumination system is designed with multi-functionality to generate multiple spectra using a single light source. This allows the system to switch between different illumination spectra for different layers without requiring separate light sources, thereby reducing overall energy consumption while maintaining measurement precision.
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
The system achieves consistent and accurate metrology measurements across multiple layers by tailoring imaging configurations to each layer's specific properties, enhancing precision, repeatability, and image quality, thereby improving overlay metrology and pattern feature measurements.
Implementation Method 1
metrology of a sub-surface layer may involve propagating an illumination beam through one or more transparent or semi-transparent layers near the surface
Implementation Method 2
receiving radiation from the sub-surface layer through the transparent or semi-transparent layers
Implementation Method 3
the one or more illumination optics include a polarizer to selectively adjust a polarization of the illumination beam
Data Source
AI summary
A metrology system may include an imaging sub-system including one or more lenses and a detector to image a sample, where the sample includes metrology target elements on two or more sample layers. The metrology system may further include a controller to determine layer-specific imaging configurations of the imaging sub-system to image the metrology target elements on the two or more sample layers within a selected image quality tolerance, where each layer-specific imaging configuration includes a selected configuration of one or more components of the imaging sub-system. The controller may further receive, from the imaging sub-system, one or more images of the metrology target elements on the two or more sample layers generated using the layer-specific imaging configurations. The controller may further provide a metrology measurement based on the one or more images of the metrology target elements on the two or more sample layers.