Methods for the in-process detection of workpieces with a monochromatic light source

Abstract

A method for use with a chemical mechanical planarization (CMP) system includes an infrared LED emitter that generates an interrogation signal and directs the interrogation signal toward a polishing pad configured to process a workpiece during the CMP procedure. A reflected signal produced in response to the interrogation signal is received by a detector, and the reflected signal is processed by a converter to produce a control signal having an analog voltage. The control signal is processed and an output is produced indicative of the presence of extraneous material proximate an area of the polishing pad when the analog voltage is measured within a predetermined range. The predetermined voltage range is established such that a variety of polishing pads having different physical characteristics may be employed without altering the position of the emitter or the operating parameters of the apparatus.

Dependencies are inferred from the claim text.