Turbo Pump Pressure Control via Dual Valve Modulation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current vacuum systems in semiconductor manufacturing face challenges in maintaining stable pressure control, especially at higher pressures and lower flows, due to limitations in throttle valve resolution and the need for costly and maintenance-intensive solutions.
Innovation Solution
A system comprising a pressure sensor, throttle valve, high-vacuum pump, and backing valve, controlled by a processor to regulate the opening sizes of the throttle and backing valves, allowing for dynamic adjustment of pumping speed without changing the turbomolecular pump's rotational speed, thereby maintaining process pressure within a preferred operating range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a throttle valve with fixed positions is used to control chamber pressure, then the valve can be simple in structure, but pressure control stability deteriorates at higher pressures and lower flows
Solution Approach 1:
The patent applies dynamics by transitioning from a static throttle valve with fixed positions to a dynamic system where the throttle valve opening is continuously adjustable. The controller dynamically modulates the throttle valve opening based on real-time pressure feedback from the chamber, enabling stable pressure control across varying operating conditions including higher pressures and lower flows where fixed-position valves fail.
Solution Approach 2:
The patent implements feedback control by using a pressure sensor to continuously monitor chamber pressure and feeding this information back to the controller. The controller then adjusts the throttle valve opening based on the difference between actual and desired pressure, creating a closed-loop system that maintains pressure stability even at higher pressures and lower flows where open-loop fixed-position control is insufficient.
2Adaptability or versatility
If the turbomolecular pump rotational speed is changed to adjust pumping speed, then pumping speed can be adjusted, but response time deteriorates due to acceleration and deceleration
Solution Approach 1:
The patent introduces an intermediary element - the throttle valve - positioned between the chamber and the pump. By adjusting the throttle valve opening, the effective pumping speed seen by the chamber is modulated without changing the pump's rotational speed. This intermediary mechanism provides rapid response time while still achieving the desired pumping speed adjustment, avoiding the slow acceleration and deceleration of the pump itself.
3Quantity of substance
If a larger turbomolecular pump is installed to achieve lower pressures with high gas flows, then lower pressures can be achieved, but control resolution deteriorates at higher pressures and lower flows
Solution Approach 1:
The patent applies dynamics by using a controller that dynamically adjusts the throttle valve opening based on real-time pressure feedback. This dynamic control provides fine resolution at higher pressures and lower flows where a fixed-position valve would have poor control, while still maintaining the high gas flow capacity of the larger turbomolecular pump for achieving lower pressures when needed.
Solution Approach 2:
The patent changes the parameter of throttle valve opening to control pressure. By varying the valve opening from fully closed to fully open positions under controller regulation, the system achieves fine pressure control resolution across the entire operating range, including the higher pressure, lower flow conditions where a larger pump alone would provide poor control.
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 provides stable and responsive pressure control across a wide range of conditions, reducing maintenance and cost while improving control stability and productivity.
Implementation Method 1
a high-vacuum pump having a pump inlet and a backing port
Implementation Method 2
Pressure in the process chamber 110 is typically measured using one or more capacitance manometer instruments 112
Implementation Method 3
a throttle valve in communication with the exhaust port of the vacuum chamber for regulating flow from the exhaust port
Implementation Method 4
a backing valve in communication with the pump backing port for regulating flow from the backing port
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The present invention is an apparatus and method for controlling a process flow rate and a pressure in a vacuum process chamber that is evacuated by a turbomolecular pump. A throttle valve between the pump and the process chamber is controlled to regulate the pressure and flow rate. A backing valve downstream of the pump is also controlled to maintain the setting of the throttle valve within a preferred, stable operating range.