Device and method for positioning a notched wafer

A method for positioning a wafer on a rotary stage with a center of the wafer aligned with a rotational center of the rotary stage, the wafer having a V-shaped notch formed in a predetermined location of an outer periphery thereof, said method comprising the steps of:

• placing the wafer on said rotary stage, at least three positioning pins being provided outwardly of the outer periphery of the wafer placed on said rotary stage;
• monitoring the outer periphery of the wafer that is rotated by rotation of said rotary stage, so as to detect an angular position of the V-shaped notch of the wafer on said rotary stage and eccentricity of the wafer relative to the rotational center of said rotary stage;
• positioning the V-shaped notch of the wafer on said rotary stage at an angular position corresponding to a predetermined one of said positioning pins on the basis of the angular position of the V-shaped notch detected by the step of monitoring;
• and
• on the basis of the eccentricity of the wafer detected by the step of monitoring, moving each of said positioning pins into contact with the wafer in such a manner that the center of the wafer lies at the rotational center of said rotary stage, wherein movement of said predetermined one of said positioning pins is in a diametric direction of said rotary stage.

A method for positioning a wafer on a rotary stage with a center of the wafer aligned with a rotational center of the rotary stage, the wafer having a V-shaped notch formed in a predetermined location of an outer periphery thereof, said method comprising the steps of:

• placing the wafer on said rotary stage, at least three positioning pins being provided outwardly of the outer periphery of the wafer placed on said rotary stage;
• monitoring the outer periphery of the wafer that is rotated by rotation of said rotary stage, so as to detect an angular position of the V-shaped notch of the wafer on said rotary stage and eccentricity of the wafer relative to the rotational center of said rotary stage;
• on the basis of the eccentricity of the wafer detected by the step of monitoring, determining whether a positioning operation to locate the center of the wafer at the rotational center of said rotary stage should be performed or not;
• and
• when it is determined that said positioning operation should be performed, fitting a predetermined one of said positioning pins into the V-shaped notch of the wafer placed on said rotary stage and moving each of said positioning pins into contact with the wafer on the basis of the eccentricity of the wafer detected by said detector, so as to position the wafer in such a manner that the center of the wafer lies at the rotational center of said rotary stage.