Exhaust flow control system

Abstract

A method of applying a layer of a flowable material to a substrate. The substrate is received with a rotatable chuck, and an amount of the flowable material is dispensed on to the substrate. The substrate is spun on the rotatable chuck, thereby spreading the flowable material across the substrate and conveying a surplus amount of the flowable material away from the substrate. An exhaust stream is created with a vacuum source. At least a portion of the surplus amount of the flowable material conveyed away from the substrate is entrained into the exhaust stream, which exhaust stream is conveyed into an exhaust system. A pressure drop is created in the exhaust stream across a vane anemometer within the exhaust system. The blow back of the entrained portion of the surplus amount of the flowable material from a downstream position in the exhaust system to the substrate is thereby reduced. Thus, positioning the vane anemometer in the exhaust system tends to create a sudden and distinct pressure drop across the vane anemometer, which tends to reduce the occurrence of blow back of the flowable material from the portion of the exhaust system that is downstream from the vane anemometer, and which is at a relatively lower pressure, to the portion of the exhaust system that is upstream from the vane anemometer, and which is at a relatively higher pressure, and which is where the substrate is processed.

Dependencies are inferred from the claim text.