The effects of argon gas flow rate and furnace pressure on oxygen concentration in Czochralski silicon single crystals grown in a transverse magneticfield

The effects of the argon gas flow rate and furnace pressure on the oxygen c oncentration in a transverse magnetic field applied Czochralski (TMCZ) sili con single crystals were examined through experimental crystal growth. A ga s controller which had been proposed by Zulehner was used for this series o f experiments. In the TMCZ gas-controlled crystals, a decrease in the oxyge n concentration with a decrease in furnace pressure was found. A clear rela tionship between the oxygen concentration and the argon gas flow rate was n ot obtained due to the limited experimental conditions. The relationships b etween the oxygen concentration and the furnace pressure and the argon gas now rate previously observed for Czochralski (CZ) crystals by a similar gas controller Mere confirmed by the present gas controller. The oxygen concen tration changes in the TMCZ and the CZ crystals were analyzed in terms of t he calculated flow velocity of the argon gas between the gas controller and the silicon melt surface. In contrast with the CZ gas-controlled crystals, the oxygen concentration was decreased with an increase in the flow veloci ty of argon gas in the TMCZ gas-controlled crystals. The surface temperatur e model and the melt flow pattern model which had been proposed in the prev ious report are discussed again in light of the present experimental result s. (C) 2000 Elsevier Science B.V. All rights reserved.