Wafer Defect Height Estimation Using Calibrated 3D SEM Models
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Solution Overview
Problem
Current methods for inspecting wafers to estimate defect heights are invasive and time-consuming, often damaging the wafer during physical inspection, which delays manufacturing and results in waste.
Innovation Solution
A method and system that create an un-calibrated 3D model from SEM images of defects, transform it into a calibrated model using a scaling factor, and estimate defect heights without physically touching the wafer, allowing for non-destructive and efficient defect measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If physical inspection using focused ion beam (FIB) cross-sectioning is used to estimate defect heights, then measurement precision is improved, but the wafer structure is damaged and the wafer is rendered useless
Solution Approach 1:
The patent creates a digital 3D model (copy) of the defect based on SEM images instead of physically cross-sectioning the wafer. This digital replica allows for virtual measurement of defect heights without touching or damaging the actual wafer structure, thus achieving measurement precision while avoiding physical harm to the object.
Solution Approach 2:
The patent replaces the mechanical/physical FIB cross-sectioning system with a computational/image-based system. Instead of using focused ion beams to physically cut and expose the defect cross-section, the system uses SEM images and 3D modeling algorithms to estimate defect heights, substituting physical mechanics with computational methods.
2Measurement precision
If physical cross-sectioning and inspection methods are used to measure defect heights, then measurement accuracy is improved, but manufacturing time is increased due to the destructive and time-consuming process
Solution Approach 1:
By creating a digital 3D model from existing SEM images, the system enables rapid virtual measurement without the time-consuming physical cross-sectioning process. The digital copy can be measured instantly using computational algorithms, dramatically reducing the time required for defect height estimation while maintaining measurement accuracy.
Solution Approach 2:
The patent performs the measurement action virtually on the digital model before any physical intervention would be needed. By pre-creating the 3D model from SEM images and using it for measurement, the system eliminates the need for subsequent physical cross-sectioning and manual inspection steps, saving significant manufacturing time.
3Productivity
If non-destructive measurement methods are used to inspect wafers, then wafer usability is preserved and manufacturing efficiency is improved, but measurement precision may be compromised compared to physical cross-sectioning
Solution Approach 1:
The patent creates a detailed digital 3D model that replicates the defect geometry with high fidelity. This digital copy preserves all necessary geometric information from multiple SEM images, enabling accurate measurement of defect heights without physical contact. The copying process maintains measurement precision while allowing the original wafer to remain usable.
Solution Approach 2:
The patent introduces a digital 3D model as an intermediary between the SEM images and the final measurement result. This intermediary structure synthesizes information from multiple images and provides a virtual platform for precise measurement, bridging the gap between non-destructive imaging and accurate quantitative assessment.
Data Source
AI summary
The present disclosure relates to a method for estimating heights of defects in a wafer. The method comprises creating an un-calibrated 3D model of a defect in a wafer, determining one or more attributes associated with the un-calibrated 3D model, transforming the un-calibrated 3D model to a calibrated 3D model, and estimating a height of the defect using the calibrated 3D model. Creating an un-calibrated 3D model corresponds to a defect present in a wafer based on a plurality of Scanning Electron Microscope (SEM) images of the defect. Transforming the un-calibrated 3D model to a calibrated 3D model uses a scaling factor corresponding to the determined one or more attributes associated with the un-calibrated 3D model. A height of the defect is estimated based on the calibrated 3D model of the defect.