Vacuum Condition Controlling Apparatus for Open-Area SEM Observation
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Solution Overview
Problem
Scanning Electron Microscopes (SEM) face challenges when used in open areas without a specimen chamber, particularly in creating a stable local gaseous environment and controlling pressure, which limits their applicability for observing large or complex specimens.
Innovation Solution
A vacuum condition controlling apparatus that includes a central channel, pumping channels, and a gas supplying system, allowing for the creation of a desired local gaseous environment and pressure control around the specimen, enabling the SEM to operate effectively in open areas by maintaining a pressure difference and supplying gases to the specimen region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If SEM is used in open area without specimen chamber, then accessibility to large specimens is improved, but pressure control stability deteriorates
Solution Approach 1:
The patent divides the open space into multiple controlled regions using separate pumping chambers (first pumping chamber for electron beam path, second pumping chamber for specimen area) that can be independently controlled. This segmentation allows the system to maintain different pressure conditions in different zones, enabling open-area operation while preserving pressure control stability where needed.
Solution Approach 2:
The patent introduces intermediary components including a pressure limiting aperture that mediates between the vacuum chamber and open environment, and gas supplying chambers that act as intermediaries to create controlled gaseous environments. These intermediaries enable the transition from closed vacuum to open area operation while maintaining necessary pressure control.
2Adaptability or versatility
If gas is injected into specimen region, then gaseous environment is created, but pressure stability deteriorates
Solution Approach 1:
The patent creates different pressure and gas composition conditions in different locations: the electron beam path maintains high vacuum through the first pumping chamber, while the specimen region can have controlled gaseous environment through the second pumping chamber and gas supplying chamber. This local differentiation allows gas injection where needed without compromising overall pressure stability.
Solution Approach 2:
The patent employs dynamic control of gas flow and pumping rates to maintain pressure stability. The gas supplying system and pumping systems work together with controllable flow rates, allowing the system to adapt to changing conditions while maintaining stable pressure in the specimen region.
3Quantity of substance
If positive pressure gas injection is used, then gas supply is achieved, but electron mean free path decreases
Solution Approach 1:
The pressure limiting aperture acts as an intermediary that allows controlled gas supply to the specimen region while maintaining a pressure gradient that preserves electron mean free path in the beam path. The aperture mediates between the need for gas supply and the need to maintain electron transport conditions.
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 solution allows for stable and controlled pressure environments, enabling the SEM to observe large or complex specimens with improved working distances and accuracy, addressing the limitations of conventional SEMs in open areas.
Implementation Method 1
a pressure limiting aperture deployed at an outlet of the central channel for keeping a pressure difference between the central channel and an external environment
Implementation Method 2
a first pumping channel connected to an external first pumping system... the first pumping channel is connected to the central channel, and is used for pumping the central channel
Implementation Method 3
a gas supplying channel for supplying gas to an area between the specimen to be tested and the apparatus via the gas supplying chamber
Implementation Method 4
a second pumping channel... connected to the second pumping system for pumping the area between the specimen and the apparatus
Data Source
Figure 1~2
Figure 3~4a
Figure 4b~4c
AI summary
A vacuum condition controlling apparatus (104), the top of which is connected with an electron beam generating instrument. The apparatus is rotationally symmetric, comprises the following parts deployed outward from the central axis: the central channel (113), the first pumping channel (107), the gas supplying chamber (106) and the at least one pumping chamber (108). A pressure limiting aperture (109) is deployed near the outlet of the central channel (113), for keeping the pressure difference between the central channel (113) and the outside environment, and allow the electron beam to go through the central channel (113); the first pumping channel (107) is connected to the central channel (113) to pump the central channel (113); the top of the gas supplying chamber (106) is connected to the gas supplying channel (106) to supply gas to the area (114) between the specimen (111) and the apparatus; the top of the second pumping channel is connected to the second pumping channel, to pump the area (114).