Low Vacuum SEM Using Ion Current Imaging for Safe Adsorption
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Solution Overview
Problem
Conventional scanning electron microscopes require high vacuum conditions for specimen observation, which is costly and poses risks of electrical discharge during electrostatic adsorption, limiting the use of inexpensive exhaust systems and making it difficult to safely adsorb rare or fragile substances.
Innovation Solution
A low vacuum SEM system that uses ion current and absorption current imaging, allowing for safe adsorption via electrostatic or shear stress methods, using a commonly available exhaust system and inert gases to prevent electrical discharge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high vacuum conditions are used for specimen observation in SEM, then observation quality is improved, but cost increases and electrical discharge risk occurs during electrostatic adsorption
Solution Approach 1:
The patent changes the vacuum parameter from high vacuum (10^-4 Pa) to low vacuum (10^2 to 10^4 Pa) conditions. This parameter change eliminates the electrical discharge risk during electrostatic adsorption while maintaining sufficient observation quality through ion current detection methods, thus resolving the contradiction between observation quality and electrical discharge risk
Solution Approach 2:
The patent introduces an inert gas atmosphere (nitrogen or argon) into the specimen chamber at low vacuum conditions. This inert environment prevents electrical discharge during electrostatic adsorption of rare or fragile substances, while still allowing adequate specimen observation, thereby resolving the contradiction between observation quality and electrical discharge risk
2Measurement precision
If high vacuum conditions are maintained, then specimen observation is enabled, but expensive exhaust systems are required
Solution Approach 1:
The patent changes the vacuum parameter from high vacuum (10^-4 Pa) to low vacuum (10^2 to 10^4 Pa) conditions. This parameter change allows the use of inexpensive exhaust systems (such as simple vacuum pumps) while still enabling sufficient specimen observation through ion current detection, thus resolving the contradiction between observation capability and exhaust system cost
3Ease of manufacture
If low vacuum conditions are used, then inexpensive exhaust systems can be used, but conventional SEM observation methods cannot be used due to electrical discharge risk
Solution Approach 1:
The patent substitutes the conventional secondary electron detection method with ion current detection method. This substitution enables effective specimen observation under low vacuum conditions where conventional methods would fail due to electrical discharge, thus resolving the contradiction between exhaust system cost and observation capability
Solution Approach 2:
The patent introduces an inert gas atmosphere (nitrogen or argon) at low vacuum conditions to prevent electrical discharge. This allows the use of inexpensive exhaust systems while maintaining observation capability through the inert environment that prevents harmful electrical discharge, resolving the contradiction between exhaust system cost and observation capability
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
Enables safe and cost-effective observation and adsorption of target substances without the risk of electrical discharge, using a low vacuum environment and inexpensive exhaust systems.
Implementation Method 1
the target substance to be adsorbed onto a probe by the agency of an electrostatic force generated between the target substance and the probe
Implementation Method 2
there is provided a scanning electron microscope capable of implementing safe adsorption of a target substance even in the case where a low vacuum atmosphere is used, by use of an imaging system by detection of an ion current and an absorption current
Implementation Method 3
by use of an imaging system by detection of an ion current and an absorption current
Data Source
AI summary
With a scanning electron microscope (SEM) adopting a commonly available exhaust system such as a turbo-molecular pump, an ion pump, or a rotary pump, and so forth, there is realized an apparatus capable of safely executing observation, or adsorption of a target substance that is high in rarity. Further, there is realized a safe SEM low in the risk of an electrical discharge by providing the apparatus with a probe, a means for replacing an atmosphere in a specimen chamber, with a predetermined gas, and a means for forming an image by detection of an ion current, and detection of an absorption current. Further, there is provided a means for controlling the polarity of a voltage applied to the probe. Still further, there is provided a control means for controlling a value of the voltage applied to the probe according to a degree of vacuum.