Processing Liquid Circulation Control to Prevent Pump Cavitation
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Solution Overview
Problem
Conventional substrate processing apparatuses face the risk of pump malfunction when increasing the flow rate of processing liquid circulation due to insufficient control mechanisms.
Innovation Solution
A processing liquid supply system with a controller that stabilizes pump operation by gradually increasing the flow rate through rotation speed control and flow rate feedback, ensuring stable circulation and temperature control before reaching the processing set flow rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the pump operates at high flow rate to increase processing liquid circulation, then productivity is improved, but pump cavitation occurs causing malfunction
Solution Approach 1:
The system performs preliminary air evacuation from the circulation path before starting pump operation. By removing air pockets in advance, the pump can immediately operate at high flow rates without cavitation, enabling rapid achievement of processing set flow rate while maintaining reliable operation
Solution Approach 2:
The flowmeter provides real-time feedback on the circulation flow rate to the controller. The controller adjusts pump operation based on this feedback to maintain the flow rate at the processing set value, ensuring both high productivity and reliable pump operation without cavitation
2Loss of time
If the pump starts immediately at high speed to achieve processing flow rate, then time is saved, but air in circulation path causes unstable operation
Solution Approach 1:
The system performs preliminary air evacuation using the air evacuation mechanism before pump startup. This preliminary action removes air pockets that would cause unstable operation, allowing the pump to start immediately at high speed and reach processing flow rate quickly while maintaining stable operation throughout
Data Source
AI summary
A processing liquid supply system includes a processing liquid supply for supplying a processing liquid into a processing tub in which a substrate is immersed to be processed; a circulation path for allowing the processing liquid to flow out from the processing tub and return back into the processing tub; a pump and a flowmeter provided in the circulation path; and a controller. The controller performs: storing the processing liquid in the processing tub; filling the circulation path with the processing liquid; circulating the processing liquid through the circulation path by operating, after the filling of the circulation path, the pump such that the processing liquid reaches a predetermined initial set flow rate; and operating, after a timepoint when a measurement value of the flowmeter has reached the initial set flow rate, the pump to achieve a predetermined processing set flow rate at which the substrate is processed.