Multi-Angle Illumination Inspection System for Semiconductor Defect Detection
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Solution Overview
Problem
Current inspection systems for semiconductor devices lose resolution due to averaging of defect information from all scattering angles, leading to a loss of inspection capability for defects that strongly scatter illumination.
Innovation Solution
A system that illuminates samples at multiple angles and independently processes image streams from each angle using a stage, illumination sources, pupil apertures, field apertures, and detectors to enhance optical resolution without altering the wavelength or numerical aperture of the optics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a large pupil aperture is used to illuminate the sample, then the inspection area is increased, but the resolution is degraded due to averaging of defect information from all scattering angles
Solution Approach 1:
The large pupil aperture is segmented into multiple smaller sub-apertures, each illuminating the sample from a different angle. This segmentation allows the system to maintain a large overall inspection area while preserving high-resolution information from each individual angle, avoiding the averaging effect that occurs with a single large aperture.
Solution Approach 2:
The system transitions from using a single large aperture in one dimension to using multiple smaller apertures distributed across angular dimensions. By illuminating from multiple angles simultaneously, the system captures defect information from different scattering directions, effectively adding an angular dimension to the inspection process and resolving the contradiction between area and resolution.
2Ease of operation
If data from all scattering angles is averaged, then the inspection process is simplified, but frequency content and resolution are lost
Solution Approach 1:
The processing is segmented by maintaining separate data streams for each sub-aperture angle rather than averaging them. Each angle's data is processed independently through its own detection and processing channel, preserving the unique frequency content and scattering information from each angle while still providing a streamlined multi-channel processing architecture.
3Measurement precision
If multiple illumination angles are used, then resolution is enhanced, but system complexity increases
Solution Approach 1:
The system employs a universal optical architecture where multiple sub-apertures share common optical components, detection systems, and processing channels. This multi-functional design allows the same hardware infrastructure to handle multiple illumination angles simultaneously, reducing the overall system complexity compared to having separate systems for each angle while still achieving enhanced resolution.
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 higher resolution by retaining frequency content, allowing for the detection of smaller defects and improving sensitivity, effectively enhancing the inspection system's resolution beyond the limitations of traditional systems.
Implementation Method 1
at least one illumination source configured to illuminate the sample by providing illumination along an illumination path
Implementation Method 2
one or more detectors configured to receive portions of light reflected, scattered, or radiated from the surface of the sample
Implementation Method 3
one or more detectors configured to receive portions of light reflected, scattered, or radiated from the surface of the sample
Data Source
AI summary
The disclosure is directed to a system and method for inspecting a sample by illuminating the sample at a plurality of different angles and independently processing the resulting image streams. Illumination is directed through a plurality of pupil apertures to a plurality of respective field apertures so that the sample is imaged by portions of illumination directed at different angles. The corresponding portions of light reflected, scattered, or radiated from the surface of the sample are independently processed. Information associated with the independently processed portions of illumination is utilized to determine a location of at least one defect of the sample. Independently processing multiple image streams associated with different illumination angles allows for retention of frequency content that would otherwise be lost by averaging information from multiple imaging angles.