Parallel Imaging Paths for Multi-Wavelength Semiconductor Inspection
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Solution Overview
Problem
Inspection systems face challenges in detecting defects on semiconductor samples with increased accuracy and precision due to reduced throughput and alignment uncertainties caused by machine drift and vibrations when imaging multiple times with different wavelengths, leading to increased inspection noise.
Innovation Solution
A system that uses parallel imaging paths to illuminate a sample simultaneously with multiple wavelengths, allowing for concurrent imaging and data collection, which enables easier alignment and differentiation of nuisance components from defect-of-interest data through comparative analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the sample is imaged multiple times with different illumination wavelengths to generate more data for defect detection, then the defect detection accuracy is improved, but the throughput is reduced
Solution Approach 1:
The imaging system is divided into multiple parallel imaging paths, each dedicated to a specific wavelength band. This segmentation allows simultaneous acquisition of multi-wavelength images without sequential processing, thereby maintaining high defect detection accuracy while significantly improving throughput by eliminating the time penalty of multiple sequential imaging operations.
Solution Approach 2:
Multiple imaging paths for different wavelength bands are merged into a single integrated inspection system that processes the sample simultaneously. The parallel architecture combines the capabilities of multi-wavelength imaging while maintaining synchronized acquisition, resolving the contradiction between detailed spectral analysis and production speed.
2Measurement precision
If the sample is imaged multiple times with different illumination wavelengths, then more data is collected for defect analysis, but alignment uncertainty increases due to machine drift and vibrations
Solution Approach 1:
The system performs preliminary alignment by capturing a reference image at a first wavelength before acquiring images at subsequent wavelengths. This preliminary action establishes a stable reference frame that compensates for machine drift and vibrations, ensuring that all multi-wavelength images remain precisely aligned throughout the acquisition sequence.
Solution Approach 2:
The system employs feedback mechanisms where images from different wavelength bands are continuously compared and realigned based on detected features. This feedback loop compensates for drift and vibration effects, maintaining alignment accuracy even during extended multi-wavelength imaging sequences.
3Loss of information
If images are collected at different times with different wavelengths, then spectral information is obtained, but inspection noise increases due to temporal fluctuations in the imaging system
Solution Approach 1:
The parallel imaging paths operate continuously and simultaneously, capturing all wavelength bands in an uninterrupted sequence during a single sample traversal. This continuous action eliminates temporal gaps between wavelength acquisitions, preventing imaging system fluctuations from introducing noise while preserving complete spectral information.
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 defect detection accuracy and reduces noise by aligning images simultaneously and improving throughput, allowing for more precise identification and classification of defects across multiple layers.
Implementation Method 1
one or more illumination sources configured to illuminate at least a portion of a surface of a sample simultaneously with at least a first wavelength of illumination and a second wavelength of illumination
Implementation Method 2
a first detector or set of detectors configured to detect illumination reflected, scattered, or radiated along a first imaging path from a selected portion of the sample
Implementation Method 3
a first detector or set of detectors configured to detect illumination reflected, scattered, or radiated along a first imaging path from a selected portion of the sample
Data Source
AI summary
The present disclosure is directed to a system for inspecting a sample with multiple wavelengths of illumination simultaneously via parallel imaging paths. The system may include at least a first detector or set of detectors configured to detect illumination reflected, scattered, or radiated along a first imaging path from a selected portion of the sample in response to the first wavelength of illumination and a second detector or set of detectors configured to concurrently detect illumination reflected, scattered, or radiated along a second imaging path from the selected portion of the sample (i.e. the same location on the sample) in response to the second wavelength of illumination, where the second imaging path may at least partially share illumination and/or detection optics with an autofocus channel.