Voltage Contrast Defect Analysis Using EBI and SEM CDU Comparison
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Solution Overview
Problem
Current defect detection methods for semiconductor devices using electron beams have low inspection coverage and reliability due to the low correlation between voltage contrast defects and critical dimension uniformity (CDU), limiting the effectiveness of defect analysis.
Innovation Solution
A voltage contrast defect analysis method and system that utilizes an electron beam inspection (EBI) machine and scanning electron microscope (SEM) to detect defects, measure critical dimensions, and compare them with reference dies to determine if defects are caused by poor CDU, increasing inspection coverage and reliability through automated analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electron beam inspection is used for voltage contrast defect detection, then defect detection capability is improved, but inspection coverage remains less than 1% which reduces reliability
Solution Approach 1:
The inspection process is segmented into multiple stages: first using EBI for voltage contrast defect detection, then using SEM for critical dimension measurement. This segmentation allows each tool to perform its optimal function while collectively achieving comprehensive inspection coverage and reliable defect analysis.
Solution Approach 2:
The patent introduces critical dimension measurement as an intermediary parameter to establish correlation with voltage contrast defects. By measuring CDU and comparing it with defect locations, the system creates a bridging relationship that enhances defect analysis reliability without requiring full-area inspection by a single tool.
2Measurement precision
If electron beam inspection is used to inspect critical dimension uniformity, then measurement capability is improved, but inspection coverage remains low which reduces correlation with voltage contrast defects
Solution Approach 1:
The patent applies local quality by performing SEM-based critical dimension measurements at specific defect addresses identified by EBI, rather than uniform inspection across the entire wafer. This targeted approach concentrates measurement precision where it is most needed - at locations with voltage contrast defects - thereby improving the correlation between CDU and defect analysis.
3Productivity
If automated defect analysis system is implemented, then analysis efficiency is improved, but system complexity increases
Solution Approach 1:
The automated system integrates multiple functions into a unified workflow: EBI performs voltage contrast defect detection, SEM performs critical dimension measurement, and the control system automatically correlates the data. This multi-functional integration improves defect analysis efficiency while managing system complexity through coordinated operation of standardized equipment.
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
The method and system enhance the reliability of defect analysis by increasing the correlation between voltage contrast defects and CDU, allowing for more accurate identification of defect causes and improving overall defect analysis efficiency.
Implementation Method 1
A voltage contrast defect detection is performed on a die to be tested by using an electron beam inspection (EBI) machine
Implementation Method 2
A first scanning electron microscope image at the defect address of the die to be tested is obtained by using a scanning electron microscope (SEM)
Data Source
AI summary
A voltage contrast defect analysis method including the following steps is provided. A voltage contrast defect detection is performed on a die to be tested by using an electron beam inspection machine to find out a defect address of a voltage contrast defect. A first scanning electron microscope image at the defect address of the die to be tested is obtained by using a scanning electron microscope. A first critical dimension of the first scanning electron microscope image at the defect address of the die to be tested is measured. The first critical dimension on the die to be tested is compared with a corresponding second critical dimension on a reference die where no voltage contrast defect occurs at the defect address to determine whether the first critical dimension and the second critical dimension are the same.