Importance

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Abstract

A system for achieving a high degree of location and orientation accuracy and repeatability of a part, such as a semiconductor wafer, for storage of the part in a cassette or placement on a process tool while being able to grasp the part, while maintaining maximally repeatable location, orientation, and cleanliness, while moving it from one tool to another, such as a process tool to a cassette. This is accomplished by providing in one case a pattern of six grooves on the circumference of a part, typically spaced 60 angular degrees apart, and a pattern of three curved contact surfaces on a gripper plate and three curved contact surfaces on a tool plate, where the plates nest such that the three curved surfaces on the gripper plate would make contact with the sides of three of the grooves in the part, and when the gripper plate that is holding the part lowers the part onto the tool plate, the three curved surfaces on the tool plate would make contact with the sides of three of the other grooves in the part as the part is unloaded from the gripper plate and comes to rest on the tool plate. Thus at all times the part position is kinematically uniquely established and mathematically defined in space which provides a high degree of repeatability, and furthermore minimizes stresses placed on the part that would otherwise occur from the typical action of clamping-type gripping mechanisms. In the second case, where it is not feasible to put grooves in the parts, the same nesting plates would each have three sets of support units that each have orthogonal curved surfaces such that when a part rests on the support points, three of the support point curved surfaces support the weight of the part, and the other three orthogonal points restrain the lateral position, In either case, the plates can be stacked horizontally, or at an inclined angle.

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First Claim