The influences of carbon, hydrogen and nitrogen on the floating zone growth of four inch silicon crystals

Abstract

Dislocation-free silicon crystals, grown without a crucible by the floating zone (FZ) technique, were developed and are produced for manufacturing high voltage and high power devices. These crystals grow under extremely complicated thermal conditions, so that the advantage of high purity may be offset by the origin of new structural defects, which do not exist with the Czochralski method. With increasing crystal diameters microdefects may act as sources for dislocation formation. Attempts were made to suppress the microdefect formation by decreasing the carbon concentration in the starting material. To suppress arcing between the inductor electrodes and/or the inductor and the growing crystal, extinguishing gases such as hydrogen and nitrogen were added to the argon ambient. While hydrogen gives rise to the origin of anomalous defects, nitrogen even has beneficial effects on the crystal quality.