Robot arm edge gripping device

An edge gripping device grips and ungrips a substrate, such as a semiconductor wafer. A blade extends in a distal direction from a base of the device. At least one distal contact member is provided at the tip of the blade. Two proximal lever arms are pivotally coupled for synchronized, oppositely directed rotation to the base. Each lever arm has at least one proximal contact member at an outer end. A biasing member is coupled to the two proximal lever arms and to an actuator to effect pivoting movement of the lever arms.

The pivoting motion moves the ends of the arms generally radially toward and away from the center of the substrate to be gripped or ungripped, thereby minimizing sliding of the substrate. The biasing member is biased to retain the lever arms in a closed position in the event of a power failure. Ramps are provided next to each contact member. The contact members and ramps are profiled to minimize the zone of the substrate edge that is contacted. The lever arms are pivotally mounted with flexural pivot members having no sliding motion, to minimize particle generation.

The edge gripping device of the present invention eliminates the need for separate actuators to move both proximal contacts. The synchronized, radial motion of the lever arms is able to provide centering of the substrate on the device, in some cases eliminating the need for a pre-aligner device. The device is able to accommodate substrates that are slightly off center on their supports or slightly warped. The edge exclusion, the zone of contact along the substrate's edge, is minimized, for example to less than 1 mm for semiconductor wafers. The lever arms are mounted using flexural pivot members that have no sliding motion, thereby minimizing particle generation.