Patent ID: 11929277
Assignee: YASKAWA AMERICA, INC.
Field: Measurement (Instruments)
Classification: CPC H  G | IPC G  H

Claim 6:
7. A method comprising:
providing a wafer platform having a wafer receiving surface configured to receive a wafer having a notch on an outer peripheral edge thereof;
providing a detector configured to scan the outer peripheral edge of the wafer to detect the notch of the wafer when the wafer is received on the wafer receiving surface;
setting a notch window defining a range of angles in which the notch is predicted to be located in relation to a start position at which the wafer is initially received on the wafer receiving surface, the start position corresponding to a sensing area of the detector; and
performing a pre-alignment operation in which the wafer is rotated from the start position to a predetermined alignment location,
wherein the pre-alignment operation is performed such that the wafer is rotated at maximum acceleration/deceleration values from the start position to a notch location detected by the detector:
where the pre-alignment operation is limited to a maximum velocity for rotation of the wafer from the start position to a notch window; and
where the pre-alignment operation is limited to a scanning velocity for rotation of the wafer within the notch window until the notch location is detected by the detector, the scanning velocity being less than the maximum velocity.