Linked Field and Pupil Signal Detection for Metrology
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Solution Overview
Problem
Metrology systems face challenges in accurately measuring the dimensions and parameters of semiconductor structures due to increasing resolution requirements, multi-parameter correlation, complex geometric structures, and the use of opaque materials, which existing optical metrology techniques struggle to address effectively.
Innovation Solution
The system simultaneously detects and processes field and pupil signals to estimate structural or process parameter values, characterize measurement conditions, and adjust focus positions, illumination, and signal contamination, enabling improved measurement accuracy and normalization of light intensity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional optical metrology techniques are used, then measurement throughput is maintained, but measurement precision deteriorates due to increasing resolution requirements and complex geometric structures
Solution Approach 1:
The patent divides the measurement system into two separate detection channels: a field detector for capturing spatial information and a pupil detector for capturing angular/directional information. This segmentation allows each detector to specialize in specific aspects of the measurement, improving overall measurement precision for complex structures while maintaining manageable system complexity through modular architecture.
Solution Approach 2:
The patent introduces a second detection dimension by adding pupil space detection to the traditional real-space field detection. This dimensional expansion captures additional information about the optical field that is not accessible through conventional single-plane detection, thereby improving measurement precision for nanoscale structures without requiring a complete redesign of the existing optical system.
2Measurement precision
If multiple measurement parameters are correlated to improve accuracy, then measurement precision improves, but processing complexity increases
Solution Approach 1:
The patent merges field measurement data and pupil measurement data into a unified analysis framework. By combining these two complementary data sets, the system correlates multiple measurement parameters (spatial distribution and angular distribution) to achieve higher measurement precision. The joint processing of both data types provides redundant information that improves accuracy while the integrated approach manages processing complexity through coordinated analysis.
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 enhances measurement precision and reliability by simultaneously processing field and pupil signals, allowing for accurate estimation of structural parameters, characterization of measurement conditions, and adjustment of focus and illumination, thereby overcoming the limitations of existing metrology techniques.
Implementation Method 1
an illumination source configured to generate illumination light
Implementation Method 2
an objective configured to collect light from the measurement site
Implementation Method 3
a field detector configured to detect light from the measurement site... and a pupil detector configured to detect light from the measurement site
Data Source
AI summary
Methods and systems for simultaneous detection and linked processing of field signals and pupil signals are presented herein. In one aspect, estimates of one or more structural or process parameter values are based on field measurement signals, pupil measurement signals, or both. In addition, the quality of the measurements of the one or more structural or process parameter values is characterized based on the field measurement signals, pupil measurement signals, or both. In some embodiments, field measurement signals are processed to estimate one or more structural or process parameter values, and pupil measurement signals are processed to characterize the field measurement conditions. In some other embodiments, pupil measurement signals are processed to estimate one or more structural or process parameter values, and field measurement signals are processed to characterize the pupil measurement conditions.