SIGNAL PROCESSING FOR FINDING SUBSTRATE NOTCH

Abstract: a notch finding apparatus includes a sensor to generate a signal that depends on an proportion of a sensing region of the sensor that is covered by a substrate, and a controller configured to cause an actuator to position a carrier head relative to the substrate with the sensing region of the sensor at an edge of the substrate, cause a motor to generate relative motion between the carrier head and the sensor such that the sensing region of the sensor scans along a circumference of the substrate, and detect an angular position of a notch in the edge of the substrate based on an initial signal from the sensor, including generating a second or higher order derivative signal from the initial signal.

Inventor(s): Nojan Motamedi, Dominic J. Benvegnu, Harry Q. Lee, Boguslaw A. Swedek

CPC Classification: B24B49/12 (MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING (grinding of gear teeth , of screw-threads ; by electro-erosion ; abrasive or related blasting ; tools for grinding, buffing or sharpening ; polishing compositions ; abrasives ; electrolytic etching or polishing ; grinding arrangements for use on assembled railway tracks ); DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS)

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