| 摘要 |
A method and apparatus for handling wafers. A wafer pick moves along a horizontal x-axis to unload a wafer from a cassette and position the wafer over a chuck. The chuck moves upwardly along a z-axis perpendicular to the surface of the wafer and lifts the wafer off the pick. The pick retracts through a slot in the chuck and a test probe moves along the x-axis to position itself over the wafer and chuck with reference to a calculated wafer center. The chuck then moves upwardly to engage the surface of the wafer with the probe. Wafer characteristics are tested at several test points located on a circle on the surface of the wafer by repeatedly lowering the chuck, rotating the chuck by a small amount, and raising the chuck to engage the wafer with the probe. The probe is then positioned to test another circle of points.
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