Charged Particle Beam Detector Using Gas Scintillation
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Solution Overview
Problem
Current charged particle beam devices face limitations in high-speed observation under low vacuum conditions due to the physical limitations of ion detection speed, which affects the quality of secondary electron images, particularly in fields like biological/chemical and semiconductor analysis, where high-vacuum secondary electron image quality is desired.
Innovation Solution
A detection method utilizing light as a signal source through the light emission phenomenon of gas scintillation, where a light guide and photomultiplier tube configuration capable of detecting light from the vacuum ultraviolet to visible region are used, combined with ion current detection, to enhance image quality and scanning speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If ion current detection method is used for low-vacuum observation, then secondary electron image quality is improved, but scanning speed is limited due to physical limitations of ion detection speed
Solution Approach 1:
The patent replaces the ion current detection mechanism with a light-based detection system. Specifically, it uses the light emission phenomenon (scintillation) that occurs when electrons and gas molecules collide, and detects this light using a photomultiplier tube. This substitution of mechanical/electrical detection with optical detection enables high-speed scanning while maintaining image quality comparable to ion current detection methods.
Solution Approach 2:
The patent changes the detection parameter from measuring ion current to measuring light intensity. By detecting the light emitted during electron-gas molecule collisions rather than the ion current itself, the system achieves both high scanning speed and good image quality. The light detection parameter allows for faster response times compared to ion current measurement.
2Productivity
If reflection electron detection is used for low-vacuum observation, then high scanning speed can be achieved, but image quality and surface information detail are reduced
Solution Approach 1:
The patent introduces light emission (scintillation) as an intermediary phenomenon to bridge between electron-gas molecule collisions and detection. Instead of directly detecting ions or reflection electrons, the system detects the light emitted during these collisions. This intermediary light signal carries information about secondary electron generation while enabling fast detection speeds.
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 allows for high-speed scanning and image quality comparable to high-vacuum secondary electron images, providing improved performance and functionality for various fields by optimizing the detection unit to handle light and ion signals effectively.
Implementation Method 1
A detection method utilizing light as a signal source through the light emission phenomenon of gas scintillation
Implementation Method 2
a light guide and photomultiplier tube configuration capable of detecting light from the vacuum ultraviolet to visible region
Data Source
AI summary
The present invention provides a scanning charged particle beam device including a sample chamber (8) and a detector. The detector has: a function of detecting light at least ranging from the vacuum ultraviolet region to the visible light region, of light (17) having image information which is obtained by a light emission phenomenon of gas scintillation when the sample chamber is controlled to a low vacuum (1 Pa to 3,000 Pa); and a function of detecting ion currents (11, 13) having image information which are obtained by cascade amplification of electrons and gas molecules. Accordingly, it becomes possible to realize a device which can deal with observation of various samples. Further, an optimal configuration of the detection unit is devised, to thereby make it possible to add value to an obtained image and provide users in wide-ranging fields with the observation image. In addition, the detector is made usable in combination with a detector for high vacuum, to thereby make it possible to provide wide-ranging users with the image, irrespective of the vacuum mode.