Method and apparatus for handling wafers
AssigneeDavid Cheng
InventorDavid Cheng
Life of this patent
Estimating the term…
Abstract
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.
Claims25
A wafer testing apparatus comprising:
- a test head;
- a chuck for supporting a wafer to be tested in an x-y plane, said chuck being positioned below said test head, wherein said chuck is incapable of movement along an x-axis and a y-axis in said x-y plane;
- a first mechanism for selectively moving said chuck along a z-axis substantially perpendicular to said x-y plane to cause an upper surface of said wafer to engage and disengage said test head;
- and
- a second mechanism for moving said test head in a plane substantially parallel to said x-y plane.
A workpiece-handling apparatus comprising:
- a test head;
- a first carriage for moving said test head in an x direction;
- a chuck for supporting a workpiece in an x-y plane below said test head, said chuck being stationary with respect to movement along an x-axis and a y-axis in said x-y plane;
- a second carriage for moving said chuck along a z-axis substantially perpendicular to said x-y plane;
- and
- a device for rotating said chuck around said z-axis.
A wafer testing apparatus comprising:
- a tester;
- a chuck having a substantially planar surface configured to hold a wafer to be tested proximate to said tester;
- a mechanism for selectively moving said chuck towards and away from said tester to selectively engage and disengage a test surface of said wafer with said tester;
- a mechanism for selectively moving said tester only in a plane substantially parallel to said substantially planar surface of said chuck such that said tester can be moved proximate said chuck at a first position suitable for testing said wafer and away from said chuck to a second position;
- and
- a handling mechanism operative to engage and disengage said wafer with said chuck when said tester is in said second position.
Dependencies are inferred from the claim text.