Multi-Angle Laser Wafer Inspection System
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Solution Overview
Problem
Conventional semiconductor inspection systems face limitations in defect detection due to single-direction illumination and sequential inspection passes, which reduce throughput and miss certain defect types, especially as semiconductor devices become increasingly sensitive to smaller defects.
Innovation Solution
A semiconductor inspection system utilizing simultaneous multiple illumination channels to generate incident beams at different azimuth angles with corresponding separated collection channels for simultaneous direction of output light to detectors, enhancing optical resolution and defect sensitivity through combination of images from various angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional single-direction illumination and sequential inspection passes are used, then the inspection system is simpler to operate, but defect detection coverage is incomplete and inspection throughput is reduced
Solution Approach 1:
The illumination system is segmented into multiple independent illumination channels, each providing light from a different azimuth angle. This segmentation allows simultaneous multi-directional illumination of the wafer, enabling comprehensive defect detection coverage without requiring sequential inspection passes, thus resolving the contradiction between versatility and complexity
Solution Approach 2:
Multiple illumination channels at different azimuth angles are merged into a single inspection system that operates simultaneously. The collection optics and sensor are shared across all channels, combining the advantages of multi-directional illumination while avoiding the complexity of multiple separate inspection systems
2Adaptability or versatility
If multiple sequential inspection passes are performed to capture different defect types, then more defect types can be detected, but inspection throughput decreases
Solution Approach 1:
The system performs continuous simultaneous illumination from multiple azimuth angles during a single wafer inspection pass, eliminating the need for sequential passes. This continuous multi-directional illumination ensures all defect types are detected in one continuous operation, maintaining high throughput while achieving comprehensive defect coverage
Solution Approach 2:
The inspection system adds the azimuth angle dimension to the illumination geometry, transitioning from single-direction to multi-directional simultaneous illumination. This dimensional expansion enables detection of various defect types (edge dislocation, pinhole, particle, scratch) in a single pass, resolving the throughput-coverage contradiction
3Measurement precision
If single-direction illumination is used, then the inspection system has lower complexity, but optical resolution and defect sensitivity are limited
Solution Approach 1:
Each illumination channel is optimized for its specific azimuth angle, providing locally optimized illumination quality for detecting defects with particular orientations. The collection optics and sensor maintain uniform high quality across all channels, achieving high optical resolution and defect sensitivity without proportionally increasing 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 improves defect sensitivity and detection capabilities by extending coverage in Fourier space, allowing for more effective detection of various defect types without compromising inspection speed, and enables high-resolution imaging beyond the limitations of conventional systems.
Implementation Method 1
illumination optics for simultaneously directing a plurality of incident beams at a plurality of azimuth angles towards a sample
Implementation Method 2
collection optics for directing a plurality of field portions of output light from at least two or more of the angles
Implementation Method 3
collection optics for directing a plurality of field portions of output light from at least two or more of the angles towards two or more corresponding sensors
Implementation Method 4
The sensors are arranged to receive the field portions and generate corresponding images
Data Source
AI summary
Disclosed is apparatus for inspecting a sample. The apparatus includes illumination optics for simultaneously directing a plurality of incident beams at a plurality of azimuth angles towards a sample and collection optics for directing a plurality of field portions of output light from two or more of the plurality of angles towards two or more corresponding sensors. The two or more sensors are arranged for receiving the field portions corresponding to two or more angles and generating two or more corresponding images. The apparatus further comprises a processor for analyzing the two or more images to detect defects on the sample.