CPC H01L 21/681 (2013.01) [G01N 21/43 (2013.01); G01N 21/9501 (2013.01); H01L 21/68 (2013.01)] | 20 Claims |
1. A pre-aligner for pre-aligning a wafer having a notch on an outer peripheral edge thereof, the pre-aligner comprising:
a rotation unit including:
a wafer platform having a wafer receiving surface configured to receive the wafer; and
a drive device configured to rotate the wafer platform about an axis;
a detector configured to detect the notch of the wafer when the wafer is received on the wafer receiving surface;
a memory configured to store 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
a controller programmed to perform a pre-alignment operation in which the wafer is rotated from the start position to a predetermined alignment location,
wherein the controller is programmed to perform the pre-alignment operation 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.
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