Method for detecting contaminants carried by a fluid

摘要

A coating method for detecting the presence of contaminants carried by a liquid that is applied as a coating on a workpiece. A tube guides the liquid along a flow path to the workpiece. A light source illuminates the liquid along the flow path with an optical fiber or other light carrier, and light is scattered by any contaminants present in the liquid. Light scattered by the contaminant particles is more intense than light scattered by the other liquid particles, and this brighter scattered light is detected by a light detector positioned adjacent to the fluid flow path. The 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 and rotated to receive a coating of the liquid.