Apparatus and method for detecting contaminants carried by a fluid

Abstract

A coating system for detecting the presence of contaminants carried by a fluid that is applied as a coating on a workpiece. A tube guides the fluid along a flow path to the workpiece. A light source illuminates the fluid along at least a portion of the flow path, and this light is scattered by any contaminants present in the fluid. Light scattered by the contaminant particles is more intense than light scattered by the other fluid particles, and this brighter scattered light is detected by a light detector positioned adjacent to the fluid flow path. If one or more contaminant particles is detected in the fluid, a warning signal can be given and/or the flow of fluid can be stopped. This coating system is particularly well suited for use in a spin-on coating process that applies a liquid, such as a photoresist material or a dielectric material, to a semiconductor wafer or other workpiece that is secured to a rotating turntable.

Dependencies are inferred from the claim text.