Systematic Defect Extraction via Segmented Wafer Inspection
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Solution Overview
Problem
The existing methods for identifying systematic defects in semiconductor wafers are time-consuming and inefficient, as they require manual review of a large number of defects, leading to potential missed systematic defects due to the high sensitivity needed for accurate identification and the time-consuming nature of scanning electron microscope reviews.
Innovation Solution
A novel method of pattern and feature grouping using an intersection method with a computerized analysis tool, such as the NanoScope Hotspot Pattern Analyzer, reduces the raw defect count by filtering out nuisance defects and prioritizing critical features, allowing for a more focused and efficient inspection process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical inspection is used to identify potential defects, then the number of potential defects identified increases, but the time required to verify systematic defects increases
Solution Approach 1:
The patent segments the verification process by dividing defects into different categories (systematic vs. random) and applying different verification strategies to each. Systematic defects are verified using targeted SEM inspection of specific regions, while random defects are handled through statistical analysis, thereby reducing overall verification time while maintaining accuracy.
Solution Approach 2:
The patent performs preliminary analysis of defect patterns and characteristics before full verification. By pre-identifying potential systematic defects based on their spatial distribution and characteristics, the system prepares targeted inspection regions, reducing the time needed for comprehensive verification while maintaining high accuracy.
2Reliability
If full SEM review of the whole wafer is performed, then systematic defects are reliably detected, but the process becomes impractically time-consuming
Solution Approach 1:
The patent applies local quality by performing high-resolution SEM inspection only on specific regions of the wafer where systematic defects are suspected, rather than uniformly inspecting the entire wafer. This targeted approach maintains high reliability for detecting systematic defects while significantly improving productivity by avoiding unnecessary inspection of defect-free regions.
Solution Approach 2:
The patent performs partial SEM review on strategically selected regions rather than complete wafer inspection. By using optical inspection to pre-identify potential systematic defect regions and then applying SEM only to those regions, the system achieves sufficient detection reliability without the excessive time cost of full wafer review.
3Measurement precision
If high sensitivity inspection is used to accurately identify defects, then the number of potential defects increases, but the complexity of manual review increases
Solution Approach 1:
The patent introduces an intermediary automated analysis system that processes the large volume of defects identified by high-sensitivity optical inspection. This intermediary system uses pattern recognition and statistical analysis to pre-filter and categorize defects, reducing the complexity of manual review while maintaining the high sensitivity benefits of the initial inspection.
Solution Approach 2:
The patent creates simplified representations or models of defect patterns from the high-sensitivity inspection data. By generating defect maps, heat maps, or statistical summaries that copy the essential information in a more manageable format, the system reduces review complexity while preserving the sensitivity-based defect identification capabilities.
Data Source
AI summary
The present disclosure provides a method of systematic defect extraction. Primary and secondary areas are defined in a wafer layout. A plurality of defects is identified by a first wafer inspection for an outside-process-window wafer. Defects located in the secondary area are removed. Defects associated with non-critical semiconductor features are also removed via a grouping process. Sensitive regions are defined around defects associated with critical semiconductor features. A second inspection is then performed on the sensitive regions for an inside-process-window wafer, thereby identifying a plurality of potentially systematic defects. Thereafter, a Scanning Electron Microscopy (SEM) process is performed to determine whether the defects in the sensitive regions of the inside-process-window wafer are true systematic defects.