Design and implementation of a 3-D mapping system for highly irregular shaped objects with application to semiconductor manufacturing

The basic technology for a robotic system is developed to automate the packing of polycrystalline silicon nuggets into fragile fused silica crucible in Czochralski (melt pulling) semiconductor wafer production. The highly irregular shapes of the nuggets and the packing constraints make this a difficult and challenging task. 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 3-D surface mapping 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 are used by the packing algorithm, which determines optimal nugget placement. The key contribution is to describe the design and implementation of an efficient and robust 3-D imaging system to map highly irregular shaped objects using conventional components in context of real commercial manufacturing processes.