Patent ID: 7521915

Claim:
An apparatus adapted to detect a particle present on a bevel of a wafer, the apparatus comprising: a substrate support adapted to support the wafer in a substantially horizontal orientation in a first plane and provide electrical contact to the wafer; the wafer being characterized by a center and a radial distance from the center to the bevel; a sensor housing positioned in a second plane at a distance from the center of the wafer, the distance measured along the second plane being greater than the radial distance and adapted to receive an edge of the wafer, the sensor housing partially surrounding the wafer on at least three sides, the sensor housing comprising: one or more probe electrodes; and one or more position sensors adapted to monitor a distance between the bevel of the wafer and the one or more probe electrodes; a translatable stage coupled to the sensor housing, wherein the translatable stage is adapted to control the distance between the bevel of the wafer and the one or more position sensors; electrical circuitry electrically coupled to the substrate support and the one or more probe electrodes and adapted to generate an electric field between the bevel of the wafer and the one or more probe electrodes, wherein the electric field creates a corona discharge from the particle; detection circuitry electrically coupled to the electrical circuitry; and a processor adapted to process electrical signals associated with the detection circuitry and thereby detect the particle present on the bevel of the wafer.