| 摘要 |
A technique for automatically compensating for differences in orientation of a workpiece, such as a rectangular substrate, a substrate cassette, a loadlock for accessing a vacuum chamber, and a substrate support on a robot mechanism. Sensors on the substrate support detect the position of a front edge of a substrate, a cassette or a loadlock, and measurements taken at the time the sensors are tripped by the edge are used to compute linear, angular and radial position corrections. More specifically, in moving a substrate from a cassette to the loadlock, the substrate support compensates for the orientation of the cassette, compensates for the orientation of the substrate within the cassette, and withdraws the substrate without contact with the cassette walls, and without the need for moving edge guides to orient the substrate. Before placing the substrate in the loadlock, the mechanism translates the substrate past a fixed sensor to determine the substrate position on the substrate support, and makes appropriate corrections to predicted linear and radial positions of the loadlock. The procedure for removing a substrate from the loadlock and placing it in a cassette employs a similar set of steps.
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