Design and implementation of a robot assisted crucible charging system

A robotic system is developed to automate the packing of polycrystalline silicon nuggets into a fragile fused silica crucible in CZ semiconductor wafer production. The highly irregular shapes of the nuggets make this a difficult and challenging task. In this system, nugget grasping is done with a three-cup suction gripper and nugget manipulation is attained with a 7-DOF SCARA manipulator. An optical 3D vision system, based on active laser triangulation, measures the nugget and crucible profiles. A model-free virtual trial and error packing algorithm determines optimal nugget placement in real time. A hybrid position-force control scheme has been implemented and tested for physical nugget placement. The integrated system achieves high production rates, required precision and cost effectiveness