METHODS AND APPARATUS FOR MONITORING THE ROTATION OF A SUBSTRATE DURING CLEANING

摘要

A method and an apparatus for monitoring the rotation of a substrate during a cleaning process are provided to use an optical sensor in a wet environment by using an arrangement of light detectors. A substrate cleaner supports and cleans a substrate(102). An optical source(112) provides a light beam(118) having a path(120) in the substrate cleaner. An optical sensor(114) is located along the path to receive the light beam from the optical source. The optical sensor detects an oriented feature(104) when the oriented feature passes through the route. The optical sensor includes an arrangement(202) of light detectors(204). The path is perpendicular to a main surface of the substrate. The path is arranged adjacent to an edge of the substrate. The substrate cleaner deposits a fluid on the substrate during a cleaning process. The optical sensor detects the oriented feature regardless of the fluid on the path.