| In the 21st century, the development and survival of human face a tremendous challenge, along with a huge opportunity. Non-renewable energy resources such as petroleum, coal, natural gas are decreasing by each day. The harmful products of fossil fuel combustion has made a invaluable bad impact on the environment. Exploitation and utilization of clean renewable energy will be the key of energy system in the future and photovoltaic industry has a vast potential for future development. In the meantime, with the rigorous development of semiconductor industry, mankind entered the information age, a fundamental change is taking place in the way of information exchange and processing, showing the trends of integration, network, intelligence. Single silicon crystal is the base material of photovoltaic and information industry, the quality of which plays a determinative effect on the products’ performance and service life. Growth of Czochralski silicon crystals is the most common and perfect one in industry and experiment research. In the past research, in order to find the best processing parameters, most of the studies are experimental method based and the results are concluded through a lot of experiments. However, experiments needs huge research funds, take a large amount of time and the reproducibility is poor.In recent years, with the development of computer technology, numerical simulation and modeling has become a important method of investigating the silicon crystal growth under different processing parameters. Using CGSim software to establish Czochralski silicon crystal growth furnace model and observe the change pattern of thermal field, flow field and stress field under different processing parameters is a mature and reliable method.In this paper, Φ200 mm and Φ450 mm Czochralski silicon crystal growth furnace models were built by CGSim, thermal field, flow field, interface shape and stress field under different pulling rate, crystal and crucible rotation rate, position of heat shield were observed, the results of two different diameter crystal growth were compared so as to investigate the structural characteristic, processing improve direction and optimality principles of large diameter silicon crystal growth furnace, this research has great academic value and practical significance for China’s further large diameter silicon growth research.Firstly, using CGSim software, a symmetric finite element model of Φ200 mm silicon crystal growth furnace was built by reference to the blueprint of TDE-90 furnace. A Φ450 mm crystal growth furnace geometry was transformed obeying the thermal field change law of large diameter crystal growth.Secondly, based on the steady processing parameters, melt thermal field, flow field, interface shape, V/G ratio, stress field under different technological parameter combinations, the results showed that:① pulling rate did no obvious influence on melt thermal field, the cold zone under interface was axial compressed with the increasing of crystal rotation rate, free surface temperature dropped when the heat shield moved far away from the triplepoint. ② thermal field stability decreased when the crystal rotation rate exceeded 12.5 rpm. ③ the convex trend of interface intensified when the pulling rate or the distance between heat shield and triplepoint increased,④ high V/G ratio corresponded to high pulling rate; V/G ratio showed a slight increasement when the crystal rotation rate was increased in the range of 1-12 rpm and decreased when the crystal rotation rate continues to grow; the position of heat shield showed little influence on V/G distribution.⑤the maximum thermal stress appeared on the side wall of crystal above the triplepoint and continued to increase when the pulling rate, crystal rotation rate were higher or the position of heat shield was lower.Finally, compared with the characteristic of Φ200 mm silicon growth, big diameter silicon growth rule was observed under different processing parameters, the results showed that: ① the cold zone beneath interface expanded along with the pulling rate, crystal rotation and crucible rotation rate increasing, ②the maximum flow speed in Φ450 mm silicon crystal melt reached 0.02～0.04 m/s. The stability of flow field improved under the combination of crystal rotation was 5 rpm and crucible rotation was 2-5 rpm. ③the convex trend of interface intensified with the pulling rate, crystal rotation rate increasing and crucible rotation rate decreasing. ④Radial V/G ratio curves rose with the pulling rate and crucible rotation rate increasing and crystal rotation rate decreasing.⑤thermal stress increased under the condition of high pulling rate, otherwise, crystal and crucible rotation had little influence on stress field. |
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