Numerical Study of Impurity Transport during the Continuous Czochralski (Ccz) Single Silicon Crystal Growth(3/3)

Nowadays Czochralski (Cz) method is popularly used to grow the single silicon ingots. However, the change of melt depth during the Cz growth and the enlargement of melt volume to pull the large size of ingot increase the formation of defects due to the fluctuations of temperature and melt velocity under the crystal-melt interface. This leads to the improvement of growth technique to overcome these disadvantages. The continuous Czochralski (CCz) technology is introduced with using more than one crucible to contain the silicon melt. It was found from literature that a uniform resistivity distribution and high minority carrier lifer can be obtained from the silicon ingots grown by CCz method because of continuously supplying silicon charge. However, there are very few publications on this topic. In order to well-control and well-optimize the silicon crystal growth process, the characteristics of the evolution of flow, heat, impurity transport, dopant transport and defect formation under different growth conditions need to be well-understood. In this study, therefore, a modeling of CCz growth is investigated with coupling the thermal, flow, and oxygen transport. The optimization of CCz growth condition and furnace geometry with the modification of the inner crucible wall to lower the point defect density and oxygen content, and obtain the higher pulling speed of crystal is also discussed.