Heat transfer in an industrial directional solidification furnace with multi-heaters for silicon ingots

• We study power distribution effects on melting, growing and annealing processes.
• Power distribution has little effect on melting time and melting sequence.
• Power distribution affects melt flow and melt-crystal interface shape significantly.
• Power distribution leads to different isotherm shapes in Si ingots when annealing.

We carried out transient global simulations of melting, growing and annealing processes in an industrial directional solidification furnace with a top and side heater. The power distribution between the two heaters was set to 3:7, 5:5 and 7:3 to investigate its effect on global heat transfer and silicon crystal growth. Quantitative comparisons of temperature distributions are presented. Increasing the top heating power slightly increases the melting time and changes the melting sequence. In the crystal growth process, adjusting the power distribution from 3:7 to 7:3 can lead to an 8–12 K change in axial temperature difference in the silicon domain. Both the intensity and pattern of the silicon melt flow are influenced by the change in power distribution. The melt-crystal interface is less convex to the melt with an increase in top heating power, especially at the final stage of solidification. In the annealing process, the ingot temperature decreases to approximately 1600 K to reduce the thermal stress and dislocation density. Isotherm shapes are different at this stage and may lead to different thermal stress and dislocation density distributions in the silicon ingot. The numerical results provide a basic understanding of the heat transfer characteristics due to power distribution in an industrial multi-heater directional solidification furnace.