Wafer presence sensor for detecting quartz wafers

摘要

An acoustic transmitter and an acoustic receiver are positioned to define a path for travel of an acoustic signal from the acoustic transmitter to the acoustic receiver. A substrate is positioned in the path so as to interrupt the acoustic signal. The acoustic receiver detects interruption of the acoustic signal. The acoustic signal path may be provided above a chamber in which the substrate is processed, such as by cleaning or drying the substrate. The acoustic signal path may be arranged at an angle relative to a plane defined by raising and lowering the substrate relative to the processing chamber. The angling of the acoustic signal path prevents interference with the signal paths provided with respect to other processing modules arranged in a linear array.