Wafer Defect Inspection Using Template-Based Coordinate Correction
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Solution Overview
Problem
Existing defect inspection apparatuses face challenges in accurately determining defect position coordinates due to errors from wafer alignment, stage movement fluctuations, and limited access to design data, which affects the precision of positional deviation correction.
Innovation Solution
The defect inspection apparatus employs a template pattern registration system, allowing semiconductor manufacturers to designate and use absolute coordinates for positional deviation correction, independent of the inspection apparatus's access to design data, by comparing template patterns with the inspected image to calculate and correct defect coordinates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the inspection apparatus calculates reference pattern coordinates using its own inspection system, then the coordinate calculation is self-contained and does not require external design data, but the calculated coordinates contain errors from wafer alignment and stage movement that reduce measurement precision
Solution Approach 1:
The patent introduces a template pattern as an intermediary reference object. Instead of directly using design data or relying solely on the inspection apparatus's own coordinate calculations, the template pattern serves as a mediator that bridges the two approaches. The template pattern is physically placed on the wafer and imaged by the inspection apparatus, allowing the system to calculate positional deviation based on the difference between the template pattern's known coordinates and its detected coordinates in the inspection image, thereby correcting defect coordinates with higher accuracy while maintaining independence from proprietary design data
Solution Approach 2:
The patent creates a physical copy of the reference pattern (template pattern) that is placed on the actual wafer. This physical template pattern copy allows the inspection apparatus to capture the pattern's position through imaging and compare it with the template pattern's designated coordinates. By copying the reference pattern onto the inspection target, the system can perform coordinate correction using only the inspection apparatus's own imaging capabilities without needing access to external design data
2Measurement precision
If design data is used for positional deviation correction, then measurement precision is improved, but the system becomes dependent on external data that may not be accessible to the inspection apparatus manufacturer
Solution Approach 1:
The patent enables the inspection apparatus to perform coordinate correction using its own imaging capabilities and the template pattern it captures. The system self-calibrates by comparing the template pattern's position in the inspection image with the template pattern's designated coordinates, calculating the positional deviation, and using this deviation to correct defect coordinates. This self-service approach eliminates dependence on external design data while maintaining high measurement precision
3Measurement precision
If template pattern coordinates are designated with absolute coordinates, then positional deviation correction accuracy is improved, but the device complexity increases due to the template pattern registration system
Solution Approach 1:
The patent performs preliminary action by pre-designating the template pattern's coordinates in the inspection apparatus before actual inspection. The template pattern's position information is stored in advance, allowing the system to quickly calculate positional deviation during inspection by comparing the pre-stored coordinates with the detected coordinates in the inspection image. This preliminary preparation simplifies the real-time correction process despite the added complexity of the registration system
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 enhances the accuracy of positional deviation correction for defect coordinates, improving the precision of defect detection and reducing errors associated with device stability and alignment issues.
Implementation Method 1
detects scattered light or reflected light generated by the light irradiation
Implementation Method 2
detects scattered light or reflected light generated by the light irradiation
Data Source
AI summary
The objective of the present invention is provide a defect inspection apparatus that increases defect position precision and can easily align a coordinate origin offset between a reviewing apparatus and the defect inspection apparatus, even when design data cannot be obtained or it is difficult to sufficiently use the design data. The defect inspection apparatus according to the present invention acquires a wafer swath image necessary for inspection, and uses the swath image to detect defects and calculate a positional deviation amount. During the calculation of the positional deviation amount, a template pattern is acquired from one arbitrary swath image via an image processing unit, and the template pattern and a plurality of swath images of the entire wafer are compared, whereby the positional deviation amount for a position corresponding to the template pattern on the wafer is calculated. For positions at which the template pattern is not present, an interpolated positional deviation amount is calculated by executing an interpolation operation by using the calculated positional deviation amount. A defect position is corrected on the basis of the positional deviation amount and the interpolated positional deviation amount, or by using a positional deviation map in which these positional deviation amounts have been mapped on the entire wafer.