Abstract: A deposition rate monitor based on the measurement of optical attenuation is described for use in deposition equipment such as sputtering systems used to deposit thin metal films on semiconductor devices. A beam of light is passed through the region between a deposition source and the deposition substrate. The beam of light is attenuated by the material being transported from the source to the substrate before the light is detected at a detector. The level of attenuation of the light passing through the deposition environment can be empirically related to the rate at which material is being deposited on the substrate. The optical absorption deposition rate monitor can be used to adjust processing variables to maintain a constant deposition rate.

Abstract: A wafer positioning system determines the position of a wafer during processing by monitoring the position of the wafer transport robot as the robot transports the wafer by one or more position sensors. The wafer positioning system incorporates a transparent cover on the surface of the wafer handling chamber and two optical position sensors disposed on the surface of the transparent cover. The position sensors direct light through the wafer handling chamber to reflectors near the floor of the chamber which reflect the light back to the position sensors. A detector within the position sensor detects when the beam path from the position sensor to the reflector is uninterrupted. As wafers are transported through the chamber, the edge of the transported wafer interrupts the position sensor beam path causing the output of the position sensor to switch states. When the position sensor output switches, the position of the wafer transport robot is measured.