Insulated gate bipolar transistor （IGBT） is a core device for energy conversion and transmission， which widely used in rail transportation， smart grid， aerospace， electric vehicles and other fields. As the substrate material for IGBT chips， the quality of lightly phosphorus-doped silicon wafers with ultra-low oxygen content plays a crucial role in the performance of IGBT chips. Due to the use of oxygen-containing quartz crucibles during the Czochralski （CZ） method for monocrystalline silicon growth， the oxygen content of the obtained silicon is typically 4×10¹⁷~9×10¹⁷ atoms/cm³， which is much higher than the oxygen content of less than 2.5×10¹⁷ atoms/cm³ required for IGBT silicon wafers. To solve the above problems， this article presents a numerical simulation of monocrystalline silicon growth using a 32 inch hot zone， and designs a new heater to produce ultra-low oxygen monocrystalline silicon ingots that meet the requirements of IGBT substrates. The simulation results show that the flow rate of silicon melt near the quartz crucible wall and solid-liquid interface decreases when using a split heater. This phenomenon is beneficial to reduce the oxygen content in the melt and the transport of oxygen impurities to the solid-liquid interface， thereby effectively reducing the overall oxygen content of the crystal rod. In addition， due to the use of a split heater， the axial temperature gradient of the crystal rod at solid-liquid interface is significantly reduced compared to conventional heaters， which is also beneficial to reduce the oxygen content in the silicon rod. The experimental results further confirmed the simulation results. The oxygen content of the monocrystalline silicon rod produced under the split heater is much lower and remains below 2.5×10¹⁷ atoms/cm³ throughout， fully meeting the requirements for IGBT substrates.