Durchflusssensor

Abstract

Flow measurements in processes like etching, cleaning, chemical mechanical polishing and coating in semiconductor manufacturing and chemical industries require high performance flowmeters. In pro-cesses like chemical mechanical polishing (CMP) it is important that as little as possible external par-ticles generated by the flowsensor reach the abrasive liquid (slurry). These particles could damage the silicon wafer, so it is advantageous to use flowmeters that do not have any moving parts. Together with Levitronix GmbH in Zurich we developed a new flowmeter for high-purity and aggressi-ve liquids. The principle of the flow sensor is based on a balance between hydrodynamic and magne-tic forces. A floating body, containing a permanent magnet is kept at a constant position in a tube by an external solenoid. The current in the solenoid required to compensate the hydrodynamic force by a magnetttttttic force, is used as a measure for the flow rate in the tube. An integrated viscosity ...