Cryogenic Chamber Evacuation Control for Faster Base Pressure
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Solution Overview
Problem
Current evacuation systems for chambers used in charged particle beam microscopes and other applications take excessively long to reach the necessary base pressure, reducing the availability of the chamber for inspection and other processes.
Innovation Solution
A system comprising a cooler and a controller that determines specific conditions to control the temperature of the cooler and the operation of pumps, such as a turbomolecular pump, to efficiently evacuate the chamber to base pressure by trapping and releasing gas molecules, thereby reducing evacuation time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If conventional evacuation systems are used to evacuate the chamber to base pressure, then the chamber reaches the required vacuum level, but the evacuation time is excessively long
Solution Approach 1:
The chamber is pre-cooled to cryogenic temperatures before evacuation begins. This preliminary cooling action causes gas molecules to condense on the cold surfaces, removing them from the gas phase before the pumping process. This preliminary removal of gas molecules significantly reduces the workload for the evacuation pumps and accelerates the overall evacuation process.
Solution Approach 2:
The invention utilizes the phase transition of gas molecules to solid/liquid state through cryogenic cooling. When the chamber is cooled to very low temperatures, gas molecules condense and freeze onto the cold surfaces, effectively removing them from the vacuum space. This phase change mechanism provides a rapid and efficient method for achieving base pressure.
2Loss of time
If the chamber is evacuated quickly using aggressive cooling and pumping, then evacuation time is reduced, but the system complexity increases
Solution Approach 1:
The cryogenic cooling system serves multiple functions: it cools the chamber to enable gas condensation, it acts as a cold trap to capture residual gases, and it provides thermal management for the chamber components. This multi-functionality reduces the need for separate dedicated components, thereby limiting the increase in system complexity despite the rapid evacuation capability.
3Ease of operation
If conventional pumping methods are used, then the system is simple to operate, but the base pressure is achieved too slowly
Solution Approach 1:
The cryogenically cooled chamber surfaces automatically capture and retain gas molecules through condensation and adsorption mechanisms. This self-service capability means the chamber walls actively participate in the evacuation process by removing gases without requiring additional active components or complex control systems, maintaining ease of operation while dramatically reducing evacuation time.
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 significantly reduces the time required to achieve base pressure, enhancing the availability of the chamber for useful applications by optimizing the evacuation process.
Implementation Method 1
A reduction in temperature of the cooler can trap gas molecules from the chamber within the cooler
Implementation Method 2
control one or more pumps to pump the chamber to a base pressure value
Data Source
AI summary
Systems and methods are provided for evacuating a chamber 101. The evacuation system comprises a cooler 320 coupled with the chamber and a controller 350. The controller is configured to determine whether a property of the cooler or the chamber satisfies one or more conditions. Based on the determination that the property satisfies the one or more conditions, the controller is configured to isolate the cooler from the chamber or control the temperature of the cooler to increase at one or more rates. The controller is further configured to control one or more pumps 330,340 to pump the chamber to a base pressure value.