SEM Inspection Flow Planning for FOV Movement and Throughput
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Solution Overview
Problem
The throughput of SEM inspections is bottlenecked when evaluating a wide range, such as the entire surface of a wafer, due to the need for precise movement of the field of view (FOV) over a large number of finer inspection points, leading to prolonged inspection times.
Innovation Solution
An inspection flow determination device that estimates inspection time by grouping inspection points into FOVs and adjusting the number of FOV movements and inspection points based on selected rules, allowing for optimized inspection data creation and execution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the number of inspection points is increased to cover a wide range of the wafer surface, then the inspection coverage is improved, but the inspection time becomes excessively long due to prolonged FOV movement
Solution Approach 1:
The patent segments the wafer surface into multiple fields of view (FOVs) and groups inspection points into different groups based on their spatial distribution. By processing each FOV independently and allowing parallel inspection of multiple FOVs, the system reduces the total inspection time while maintaining comprehensive coverage of the entire wafer surface.
Solution Approach 2:
The patent performs preliminary grouping of inspection points into multiple FOV groups before actual inspection begins. This pre-organization allows the system to plan optimal inspection sequences and prepare for parallel processing, thereby reducing the overall inspection time without compromising coverage.
2Measurement precision
If the FOV movement is performed frequently to inspect all inspection points, then the inspection precision is improved, but the throughput is reduced due to prolonged inspection time
Solution Approach 1:
The patent divides inspection points into multiple groups corresponding to different FOVs, allowing the system to inspect multiple groups in parallel. This segmentation maintains precise inspection of each point while reducing the sequential FOV movement required, thereby improving throughput without sacrificing precision.
Solution Approach 2:
The patent enables continuous inspection by organizing multiple FOV groups to be inspected in an overlapping or parallel manner. The inspection process continues without idle FOV movement time between sequential inspections, maintaining productive action throughout the inspection cycle.
3Ease of manufacture
If the inspection points are extracted without considering FOV movement, then the extraction simplicity is improved, but the inspection time exceeds the specified time limit
Solution Approach 1:
The patent segments inspection points into multiple FOV-based groups during the extraction phase. This segmentation is integrated into the extraction process itself, so that points are assigned to groups based on their spatial coordinates and FOV boundaries. The segmentation enables time estimation and optimization without adding complex post-processing steps.
Solution Approach 2:
The patent implements feedback mechanisms where the estimated inspection time is calculated based on the number of FOV movements required for each extraction condition. This feedback allows the system to adjust extraction parameters and selection criteria to ensure the final inspection plan meets the specified time limit while maintaining extraction simplicity.
4Productivity
If the number of FOV movements is reduced to shorten inspection time, then the inspection speed is improved, but the number of inspection points that can be covered is reduced
Solution Approach 1:
The patent segments the inspection task into multiple independent FOV groups that can be processed in parallel. By reducing FOV movements within each group while maintaining multiple groups, the system achieves faster inspection speed without reducing the total number of inspection points covered across all groups.
Solution Approach 2:
The patent transitions from sequential single-FOV inspection to parallel multi-FOV inspection, adding a temporal dimension to the inspection process. Multiple FOVs are inspected simultaneously rather than one after another, effectively increasing the inspection capacity without requiring proportional increases in FOV movements.
Data Source
AI summary
An inspection flow determination device including an inspection time estimation unit configured to estimate an inspection time required to inspect an inspection point extracted under a predetermined condition based on grouping data in which inspection points of a wafer are grouped to belong to at least one field of view (FOV); and an inspection data extraction unit configured to extract an inspection point using the condition selected based on the estimated inspection time as an extraction condition. The inspection time estimation unit extracts an inspection point from the grouping data based on an FOV selection rule for determining whether to perform or skip FOV movement using the number of times of FOV movement as a parameter, and an inspection point selection rule for determining whether to inspect or skip an inspection point using the number of inspection points to be actually inspected in the FOV as a parameter.