Vacuum Valve Dual-Stage Actuation for Backlash-Free Fine Control
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Solution Overview
Problem
The existing vacuum valve systems for semiconductor manufacturing, which use a feed screw drive method, face insufficient fine adjustment performance due to backlash in the feed screw mechanism, limiting precise pressure adjustment in vacuum chambers.
Innovation Solution
A vacuum valve system incorporating a combination of a coarse adjustment driver using a ball screw actuated by a stepping motor and a fine adjustment driver with a magnetic levitation actuator, where the magnetic levitation actuator provides high-resolution positioning with a smaller movement amount than the coarse adjustment driver, allowing for improved accuracy in valve body positioning and pressure control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a feed screw drive method is used to control valve body opening/closing, then the valve body can be driven up and down, but backlash of the feed screw mechanism causes insufficient fine adjustment performance
Solution Approach 1:
The valve body drive system is segmented into two independent drive mechanisms: a first up-down driver (feed screw mechanism) for coarse positioning and a second up-down driver (magnetic levitation actuator) for fine positioning. This segmentation allows each mechanism to specialize in its strength while overcoming the limitations of using a single mechanism for both functions.
Solution Approach 2:
The second up-down driver replaces the traditional mechanical feed screw mechanism with a magnetic levitation actuator that uses magnetic fields instead of mechanical contact. This substitution eliminates backlash inherent in mechanical threaded connections while providing high-precision positioning capability.
2Manufacturing precision
If a single up-down driver is used, then the device structure is simpler, but fine adjustment performance is insufficient due to backlash
Solution Approach 1:
The positioning function is segmented into coarse adjustment (first driver) and fine adjustment (second driver), with each driver optimized for its specific function. The first driver handles large movements while the second driver handles micrometer-level adjustments.
Solution Approach 2:
The control system merges the outputs of two independent drive mechanisms to achieve the final valve body position. The controller coordinates both drivers to work together, combining the advantages of mechanical robustness and magnetic precision.
3Measurement precision
If magnetic levitation actuator is used for fine adjustment, then positioning accuracy is improved, but the device requires more complex control
Solution Approach 1:
The magnetic levitation actuator incorporates feedback control through sensors that continuously monitor the valve body position and adjust the magnetic field strength accordingly. This closed-loop control compensates for disturbances and maintains high positioning accuracy.
Solution Approach 2:
A controller acts as an intermediary between the two drive mechanisms, coordinating their operations. The controller receives position commands, distributes appropriate commands to each driver based on current position and required precision, and integrates their effects to achieve the target position.
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 configuration enhances the fine adjustment performance of the vacuum valve, enabling precise control of the valve body movement and pressure adjustment in vacuum chambers, effectively addressing the limitations of backlash in traditional systems.
Implementation Method 1
The second up-down driver is a magnetic levitation actuator configured to magnetically levitate and support the valve body in an up-down drive direction
Implementation Method 2
The first up-down driver is a linear actuator using a ball screw to be driven by a stepping motor
Data Source
AI summary
A vacuum valve for driving a valve body arranged facing a valve opening up and down relative to the valve opening to perform valve opening/closing operation, comprises: a first up-down driver configured to drive the valve body up and down with a first minimum drivable amount; and a second up-down driver configured to drive the valve body up and down with a second minimum drivable amount smaller than the first minimum drivable amount.