Variable Conductance Valve Load Lock Turbulence Control
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Solution Overview
Problem
The operation of vacuum pumps in load locks for disk processing systems causes turbulent gas flow, dislodging microscopic particles from chamber surfaces and contaminating substrates, leading to defects in finished articles.
Innovation Solution
A load lock system equipped with a variable conductance valve controlled by an electromechanical actuator or processor, which gradually adjusts the flow rate during evacuation to reduce turbulence and minimize particulate contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a vacuum pump is used to evacuate the load lock chamber, then the chamber reaches partial vacuum necessary for substrate processing, but turbulent gas flow dislodges microscopic particles from chamber surfaces and contaminates substrates
Solution Approach 1:
The patent applies a variable conductance valve that dynamically adjusts the flow rate during the evacuation process. The valve transitions from a fully open state to a gradually closing state, creating a soft roughing effect that reduces gas flow velocity and turbulence. This dynamic adjustment allows the system to achieve the necessary vacuum level while minimizing particulate dislodgement and substrate contamination.
Solution Approach 2:
The patent changes the conductance parameter of the valve throughout the evacuation process. By varying the valve opening degree as a function of time or pressure, the system optimizes the balance between evacuation speed and turbulence reduction. This parameter change enables controlled gas flow that achieves vacuum without causing excessive particle dislodgement from chamber surfaces.
2Productivity
If the valve conductance is kept high for fast evacuation, then productivity is improved, but gas flow turbulence increases and causes more particulate contamination
Solution Approach 1:
The patent implements a time-dependent valve control strategy where the valve conductance varies during the evacuation process. The valve starts in a fully open position for rapid initial evacuation, then gradually closes as the process progresses. This periodic adjustment of conductance allows the system to achieve fast initial vacuum establishment while reducing turbulence in the later stages to minimize contamination.
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
The controlled evacuation process effectively reduces particulate contamination, minimizing defects in substrates and ensuring a cleaner vacuum environment for downstream processes.
Implementation Method 1
valve controller having an electromechanical actuator configured to control the conductance of the valve
Implementation Method 2
The operation of the vacuum pump during the evacuation process tends to cause a turbulent flow of gas in the load lock chamber
Data Source
AI summary
A station for a disk processing system includes a load lock chamber, a variable conductance valve configured to connect the chamber to a vacuum pump, and valve controller. The valve controller may include a processor that controls an electromechanical actuator to adjust the conductance of the valve during the evacuation of the chamber.