Joint Electron-Optical Column for Wafer Flooding and Imaging
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Solution Overview
Problem
Traditional voltage contrast wafer inspection systems require large, expensive electron-optical systems, necessitate re-alignment of electron-optical elements between flooding and imaging scans, and suffer from poor image-forming resolution during inspections.
Innovation Solution
A scanning electron microscopy system utilizing a joint electron-optical column for both flood-charging and image-forming scans, which includes a double-lens assembly and a beam limiting aperture, allowing for efficient switching between flooding and imaging modes to improve resolution and throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional voltage contrast wafer inspection systems use separate electron-optical systems for flooding and imaging, then the system can perform both functions, but the device complexity and cost increase significantly
Solution Approach 1:
The patent combines the flooding electron-optical system and imaging electron-optical system into a single integrated electron-optical column. The same electron source, lenses, and scanning mechanisms are used for both flooding scans (to charge the wafer surface) and imaging scans (to detect defects), eliminating the need for separate systems and reducing overall complexity
Solution Approach 2:
The electron-optical system is designed to perform multiple functions using the same hardware components. By switching between flooding mode and imaging mode through software control and parameter adjustment, the system achieves versatility without requiring duplicate equipment, thereby reducing cost and complexity
2Adaptability or versatility
If traditional systems use separate electron-optical systems for flooding and imaging, then both functions can be performed, but re-alignment of electron-optical elements is required between scans
Solution Approach 1:
The patent merges the flooding and imaging functions into a single electron-optical column, eliminating the physical separation between systems. Since both functions use the same optical path and components, no re-alignment is needed when switching between flooding scans and imaging scans, saving time and improving efficiency
3Device complexity
If traditional voltage contrast inspection systems use a single electron-optical system for both flooding and imaging, then device complexity is reduced, but image-forming resolution deteriorates
Solution Approach 1:
The patent employs dynamic adjustment of electron-optical parameters during operation. The system can switch between flooding mode (with higher beam current for charging) and imaging mode (with optimized parameters for resolution) by dynamically adjusting lens currents, beam energy, and other parameters to maintain high image-forming resolution while using a single integrated 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
The system reduces the complexity and cost of electron-optical components, enhances image-forming resolution, and increases the throughput of voltage contrast inspections by enabling rapid flood-charging and high-resolution imaging with a single set of optical elements.
Implementation Method 1
an electron source configured to generate an electron beam, and an electron-optical column configured to direct the electron beam to a sample
Implementation Method 2
a detector assembly configured to detect electrons scattered from a surface of the sample
Data Source
AI summary
A scanning electron microscopy system may include an electron-optical sub-system and a controller. The electron-optical sub-system may include an electron source and an electron-optical column configured to direct an electron beam to a sample. The electron-optical column may include a double-lens assembly, a beam limiting aperture disposed between a first and second lens of the double-lens assembly, and a detector assembly configured to detect electrons scattered from the sample. In embodiments, the controller of the scanning electron microscopy system may be configured to: cause the electron-optical sub-system to form a flooding electron beam and perform flooding scans of the sample with the flooding electron beam; cause the electron-optical sub-system to form an imaging electron beam and perform imaging scans of the sample with the imaging electron beam; receive images acquired by the detector assembly during the imaging scans; and determine characteristics of the sample based on the images.