Charged Particle Beam Device Asynchronous Inspection
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Solution Overview
Problem
Current charged particle beam inspection devices for substrates with circuit patterns are limited by slow inspection speeds, requiring significant time to cover large areas like a 300 mm diameter wafer, with conventional swath sampling methods only achieving a 20 times speed increase, which is insufficient for efficient defect detection.
Innovation Solution
Implementing a charged particle beam device that selectively samples and inspects partial regions of interest (ROI) by moving the sample stage and deflecting the beam, allowing for asynchronous beam scanning and deflection control to capture images at higher speeds without compromising accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional swath sampling is used to reduce the number of scanning stripes, then inspection speed is improved, but inspection coverage area is reduced
Solution Approach 1:
The inspection area is divided into multiple regions of interest (ROIs) that are selectively inspected. Instead of uniformly sampling the entire substrate, the method segments the inspection into critical areas where defects are most likely to occur, allowing faster inspection while maintaining adequate coverage of important regions.
Solution Approach 2:
Different inspection strategies are applied to different regions of the substrate. High-density sampling is applied to critical regions where defects would have severe impact, while lower-density sampling is applied to less critical areas, optimizing the balance between inspection speed and coverage.
2Loss of time
If the number of scanning stripes is reduced for high-speed inspection, then inspection time is decreased, but defect detection accuracy may be compromised
Solution Approach 1:
Regions of interest are pre-identified based on historical defect data, circuit pattern complexity, and criticality analysis before the inspection begins. This preliminary segmentation allows the inspection system to focus resources on areas most likely to contain defects, maintaining detection accuracy while reducing overall inspection time.
Solution Approach 2:
The patent replaces uniform mechanical scanning with an intelligent, adaptive scanning pattern that uses computational algorithms to determine which regions require inspection and at what density. This substitution of mechanical uniformity with computational intelligence maintains detection accuracy while enabling faster inspection.
3Productivity
If asynchronous beam scanning and stage movement are implemented, then inspection speed is increased, but system complexity increases
Solution Approach 1:
The inspection system transitions from synchronous, fixed-rate scanning to dynamic, asynchronous scanning where the beam scanning rate and stage movement speed are independently controlled and adjusted. This allows the system to optimize performance for different regions and defect types, achieving higher speeds while adapting to varying inspection requirements.
Solution Approach 2:
The system implements feedback control mechanisms that continuously monitor the positions of the beam and stage, and adjust their respective rates to maintain proper synchronization and image quality. This feedback loop manages the complexity of asynchronous operation by automatically coordinating the independent movements.
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 defect candidate extraction at significantly higher speeds than conventional methods, potentially increasing inspection speed by 4 to 10 times, thereby reducing the time required to inspect large substrates like a 300 mm diameter wafer.
Implementation Method 1
irradiating a sample with a charged particle beam
Data Source
AI summary
There is provided a substrate inspection device which uses a charged particle beam and is capable of more quickly extracting a defect candidate than ever before. The configuration of the substrate inspection device is such that a substrate having a circuit pattern is irradiated with a primary charged particle beam, the substrate is moved at a constant speed or at an increasing or a decreasing speed, a position resulting from the movement is monitored, the position of irradiation with the primary charged particle beam is controlled according to the coordinates of the substrate, an image in a partial region on the substrate is captured at a speed lower than the velocity of the movement, a defect candidate is detected based on the captured image, and the detected defect candidate is displayed in a map format.