The design of a 3D surface geometry acquisition system for highly irregular shaped objects: with application to CZ semiconductor manufacture

A robotic system is being developed to automate the crucible packing process in CZ semiconductor wafer production. It requires the delicate manipulation and packing of highly irregular polycrystalline silicon nuggets, into a fragile fused silica crucible. For this application, a dual optical 3D surface geometry measuring system that uses active laser triangulation has been developed and successfully tested. One part of the system measures the geometry profile of a nugget being packed and the other the profile of the nuggets already in the crucible. A resolution of 1 mm with 15 KHz sampling frequency is achieved. Data from the system is used by a packing algorithm to determine optimal nugget placement. The system is shown to achieve high production rates, required precision and cost effectiveness.