The three-dimensional time-dependent flow of the silicon melt in an electromagnetic Czochralski (EMCZ) crystal growth system with cusp-shaped magnetic fields was numerically investigated. Calculations were carried out using five different configurations of the melt and cusp-shaped magnetic fields. The results indicated that oxygen was transferred from a part of a sidewall of the crucible on which a cusp plane of the magnetic fields exists. The results also showed that the oxygen concentration at the solid-liquid interface of silicon increased when the cusp plane of the cusp-shaped magnetic fields shifted from the bottom of the crucible to the surface of the melt. (C) 2003 The Electrochemical Society.