Optical Inspection System for Semiconductor Defect Classification
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Solution Overview
Problem
Traditional defect classification tools in semiconductor fabrication are limited in sensitivity to small particle sizes and throughput, and require separate tools for defect location and classification, which increases turnaround time and is not cost-effective.
Innovation Solution
The implementation of an optical inspection system that detects and classifies defects based on the phase of dark field scattering by measuring the relative phase of scattered light from multiple locations in the collection pupil, allowing for simultaneous defect inspection and classification with improved sensitivity and throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional separate defect review tools are used for classification, then measurement precision is improved, but productivity deteriorates due to insufficient throughput and increased turnaround time
Solution Approach 1:
The patent combines defect detection and classification functions into a single optical inspection tool. The system integrates multiple imaging modes (bright field, dark field, phase contrast) and material classification capabilities (Raman spectroscopy, photoluminescence) within one instrument, eliminating the need to transfer wafers between separate tools and enabling simultaneous detection and classification in one inspection pass.
Solution Approach 2:
The optical inspection tool is designed to perform multiple functions: defect detection, defect classification, and material characterization. The system can switch between different imaging modes and analysis techniques to handle various defect types and materials, making a single tool versatile enough to replace multiple specialized tools while maintaining high throughput.
2Measurement precision
If EDX or SIMS techniques are used for defect composition analysis, then measurement precision is improved, but productivity deteriorates due to destructive analysis and long turnaround time
Solution Approach 1:
The patent replaces destructive mechanical/chemical analysis methods (EDX, SIMS) with non-destructive optical analysis techniques. The system uses light-based methods including Raman spectroscopy, photoluminescence, and optical imaging to characterize defect materials, eliminating the need for physical sample removal, destruction, or lengthy processing while providing immediate results.
Solution Approach 2:
The optical inspection tool performs material classification independently without requiring transfer to separate analytical instruments. The system self-containedly provides both defect detection and material characterization functions, eliminating the time-consuming workflow of moving samples between tools and enabling immediate classification results.
3Measurement precision
If phase shifting phase contrast imaging is used to classify defects, then measurement precision is improved, but productivity deteriorates due to limited photon collection and reduced sensitivity
Solution Approach 1:
The patent segments the collection pupil into multiple zones to simultaneously collect both specularly reflected light and scattered light. By dividing the pupil plane into different regions that can be independently controlled, the system captures phase information from scattered light while maintaining sufficient photon collection from specular reflection, thereby improving sensitivity without sacrificing throughput.
Solution Approach 2:
The system transitions from a single imaging mode to multiple imaging modes (bright field, dark field, phase contrast) that can be combined. By adding the dimension of multiple complementary imaging techniques, the system overcomes the limitations of phase contrast alone, achieving both high sensitivity for small particles and maintained throughput through synergistic combination of modes.
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 enables non-destructive, immediate defect classification with increased sensitivity and throughput, reducing turnaround time and eliminating the need for separate tools, thus enhancing the efficiency of semiconductor wafer inspection processes.
Implementation Method 1
detecting and classifying defects based on the phase of dark field scattering from a sample
Implementation Method 2
measuring the relative phase of scattered light collected from at least two spatially distinct locations in the collection pupil
Data Source
AI summary
Methods and systems for detecting and classifying defects based on the phase of dark field scattering from a sample are described herein. In some embodiments, throughput is increased by detecting and classifying defects with the same optical system. In one aspect, a defect is classified based on the measured relative phase of scattered light collected from at least two spatially distinct locations in the collection pupil. The phase difference, if any, between the light transmitted through any two spatially distinct locations at the pupil plane is determined from the positions of the interference fringes in the imaging plane. The measured phase difference is indicative of the material composition of the measured sample. In another aspect, an inspection system includes a programmable pupil aperture device configured to sample the pupil at different, programmable locations in the collection pupil.