Effect of Heater Structure on Oxygen Concentration in Large Diameter N-Type Czochralski Silicon Study Using Numerical Simulation

Abstract

During the growth of large-diameter N-type Czochralski (Cz) silicon, oxygen is a major impurity in the single-crystal silicon rod, seriously affecting the cell efficiency of monocrystalline silicon wafers. To reduce the oxygen concentration in the silicon crystal to improve wafer cell efficiency. In this paper, a 2D global quasi-steady axisymmetric model is established based on the N-type 252 mm diameter single-crystal silicon growth process, the effect of different heater structures on the oxygen concentration in the hot zone, the crystal, and the melt of the Cz furnace are investigated using the FVM method. The results show that when the height of the heater is increased from 210mm to 300mm, the view factor from the heater to the crucible rises from 0.475 to 0.679. Heater power is reduced from 46.8 kw to 46.73 kw, and the average value of oxygen concentration in the head silicon wafer of the single-crystal silicon rod increased from 10.51ppma to 10.81ppma. This shows that increasing the height of the heater reduces power consumption. However, it will increase the oxygen concentration of the silicon wafer at the head of the single-crystal silicon rod. By reducing the slot depth, using a heater with a height of 260 mm, a top slot depth of 140 mm, and a bottom slot depth of 200 mm, the heater power is reduced by 10%. Detecting the oxygen concentration of silicon wafers using Fourier transform infrared spectroscopy, the oxygen concentration decreased by 1.324 ppma. This study provides a theoretical basis for the design of oxygen-reducing heaters in large-diameter N-type Cz furnaces.

Keywords: heat transfer, Computer simulation, Oxygen concentration, Czochralski method