SEM Defect Review Using Dynamic Imaging Mode Switching
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Solution Overview
Problem
Automated defect review systems using scanning electron microscopes often fail to detect defects that are classified as SEM non-visible, as they are not visible in the initial imaging configuration, leading to incomplete defect identification.
Innovation Solution
The system configures the SEM to alternate between two imaging configurations: a physical mode with low landing energy and low beam current to detect secondary electrons for surface defects, and a backscattered electron mode with high landing energy to detect backscattered electrons for buried defects, allowing for comprehensive defect detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a pre-set electron beam configuration (secondary electron mode) is used in the SEM, then the imaging process is simple and fast, but many defects remain non-visible and undetected
Solution Approach 1:
The patent implements dynamic switching between different SEM imaging configurations (secondary electron mode, backscattered electron mode, and other modes) based on the defect characteristics. The system automatically selects and switches between imaging modes to optimize both review speed and detection accuracy, resolving the contradiction between simple/fast imaging and comprehensive defect visibility.
Solution Approach 2:
The patent changes key imaging parameters including electron beam energy (landing energy), beam current, and detection mode (secondary electron vs. backscattered electron) to adapt to different defect types. By adjusting these parameters dynamically, the system achieves both efficient processing and high detection accuracy across various defect scenarios.
2Measurement precision
If multiple imaging configurations are used to detect all defect types, then defect detection accuracy improves, but the review process becomes more complex and time-consuming
Solution Approach 1:
The patent performs preliminary classification of defects based on inspection system data before SEM review. This preliminary action allows the system to pre-determine which imaging configurations are needed for each defect, avoiding unnecessary mode switching and reducing operational complexity while maintaining high detection accuracy.
Solution Approach 2:
The system uses feedback from the initial inspection and from intermediate imaging results to dynamically adjust the imaging configuration. This feedback mechanism ensures that the most appropriate imaging mode is selected for each defect, reducing unnecessary complexity while maintaining high detection accuracy.
3Measurement precision
If multiple imaging configurations are used to review all defects, then comprehensive defect identification is achieved, but the review time increases
Solution Approach 1:
The patent segments the defect review process into different stages based on defect characteristics and risk levels. High-priority or suspicious defects receive multiple imaging configuration reviews, while low-priority defects are reviewed with standard configurations. This segmentation reduces overall review time while maintaining comprehensive detection for critical defects.
Solution Approach 2:
The patent applies partial action by using multiple imaging configurations only when necessary based on defect characteristics. For defects that are clearly visible in the initial configuration, additional modes are not applied. For ambiguous or critical defects, the system applies excessive action by reviewing in multiple modes to ensure detection, optimizing the balance between review time and detection accuracy.
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 the detection and classification of both visible and non-visible defects, ensuring thorough inspection and review of semiconductor wafers by switching between imaging modes to capture defects at or below the substrate surface.
Implementation Method 1
an electron beam column configured to generate an incident electron beam and scan the incident beam over a surface of a target substrate
Implementation Method 2
a detector configured to detect secondary electrons
Implementation Method 3
a backscattered electron mode with high landing energy to detect backscattered electrons for buried defects
Data Source
AI summary
One embodiment relates to a method of reviewing defects using a scanning electron microscope (SEM). A defect location having a defect for review is selected, and the SEM is configured to be in a first imaging configuration. The selected defect location is imaged using the SEM to generate a first SEM image of the selected defect location. A determination is made as to whether the defect is visible or non-visible in the first SEM image. If the defect is non-visible in the first SEM image, then the SEM is configured to be into a second imaging configuration, the selected defect location is imaged using the SEM to generate a second SEM image of the selected defect location, and a further determination is made as to whether the defect is visible or non-visible in the second SEM image. Other embodiments, aspects and features are also disclosed.