Wafer Defect Detection Using Multi-Channel Inspection
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Solution Overview
Problem
Current wafer inspection methods fail to accurately detect defects due to reliance on graphical data stream (GDS) data, which may not be available, and suffer from alignment inaccuracies and inefficiencies in nuisance defect suppression, especially when defect signals are weak.
Innovation Solution
A computer-implemented method using defect-specific information from multiple channels, acquiring images of patterns of interest (POI) and known defects of interest (DOI) with different optics modes, decoupling pattern search sensitivity from defect detection sensitivity, and employing micro care areas for precise defect detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If GDS data and swath-based alignment are used to detect defects, then defect detection coverage is improved, but alignment accuracy deteriorates due to image distortion in large swath images
Solution Approach 1:
The patent divides the wafer inspection into multiple small fields of view (FOVs) instead of using a single large swath image. Each small FOV is imaged separately with high resolution, avoiding the distortion problems of large-scale imaging while collectively covering the entire wafer surface for comprehensive defect detection.
Solution Approach 2:
The patent transitions from two-dimensional swath-based alignment to three-dimensional stacked FOV imaging with depth information. By capturing images at multiple depths and combining them, the system achieves accurate defect localization without relying on distorted large-area alignment, adding a depth dimension to the inspection process.
2Measurement precision
If multi-channel inspection with multiple optics modes is used, then defect detection sensitivity is improved, but system complexity increases
Solution Approach 1:
The patent implements a multi-channel inspection system where a single integrated device performs multiple functions: bright-field channel for general defect detection, dark-field channel for high-contrast defect detection, and oblique illumination channel for surface defect detection. This universal system handles various defect types without requiring separate specialized equipment for each mode.
Solution Approach 2:
The patent combines multiple optics modes (bright-field, dark-field, oblique illumination) into a single integrated inspection system that captures images simultaneously or sequentially. By merging these channels and processing their combined data, the system achieves enhanced defect detection sensitivity while avoiding the complexity of operating multiple separate inspection devices.
3Reliability
If defect detection is performed after acquiring entire wafer images, then comprehensive defect coverage is improved, but inspection time increases significantly
Solution Approach 1:
The patent segments the wafer inspection process into multiple small FOV regions that are imaged and processed independently and in parallel. This segmentation allows simultaneous processing of multiple regions, significantly reducing total inspection time while maintaining comprehensive coverage of the entire wafer surface through the collective analysis of all FOV segments.
Solution Approach 2:
The patent performs preliminary defect detection and filtering at the small FOV level before combining results for wafer-level analysis. By pre-processing and identifying potential defects in each small FOV independently, the system reduces the computational burden of full-wafer image processing and accelerates the overall inspection throughput while maintaining detection accuracy.
Data Source
AI summary
Methods and systems for detecting defects on a wafer using defect-specific and multi-channel information are provided. One method includes acquiring information for a target on a wafer. The target includes a pattern of interest (POI) formed on the wafer and a known defect of interest (DOI) occurring proximate to or in the POI. The method also includes detecting the known DOI in target candidates by identifying potential DOI locations based on images of the target candidates acquired by a first channel of an inspection system and applying one or more detection parameters to images of the potential DOI locations acquired by a second channel of the inspection system. Therefore, the image(s) used for locating potential DOI locations and the image(s) used for detecting defects can be different.