Si crystal growth by the Czochralski method is simulated within a conjugated 2D/3D numerical approach, using CGSim package. A modification of the furnace geometry is suggested to increase the growth rate. The computations have revealed new possible reasons of macro-dislocation formation in the crystal. A new growth regime is recommended to reduce the probability of dislocation generation. The experiments provided in PCMP have shown that the application of the modified furnace design allows increasing the growth rate by 15-30%, while the new growth parameters allow decreasing the probability of macro-dislocation generation by a factor of 2-4. (C) 2007 Published by Elsevier B.V.