Wolfgang Keller

Float-Zone Grown Silicon

Float-zone grown silicon today is a material of unsurpassed crystal quality and purity, which is of paramount importance as starting material for the electronics industry. This article describes the historical development up to the present state, gives a survey of the processes leading to the starting material, the polycrystalline silicon rods, and depicts the usual technology of the float-zone process, especially the dislocation-free crystal pulling technique. Moreover, silicon crystallography, the properties of silicon crystals, and the crystal defects, which are found in float-zone grown silicon, are described. Of course, important doping methods for preparing semiconductor silicon are referred to. Finally, a comparison is made with the other important crystal growth technique, crucible pulling, and the present and future trends are outlined. A discmsion of the method is given inl).