Distribution And Control Method Of Oxygen And Carbon In CZSi

CZSi wafer as the good semiconductor materials for solarcells, the conversion efficiency of solar cells have a great relationship with impurities in silicon. CZSi wafer were produced first from raw material the polysilicon to the single crystal silicon and then by a series of processing from the single crystal silicon, which made the impurity content of silicon have taken place a series of changes.In this paper, the oxygen and the carbon are studied in CZSi. Firstly the main reason of forming oxygen and the carbon is researched on the basis of understanding the technics and principle of CZSi production, and CZSi production equipment and technics are changed or adjusted.The results of experiments indicate as follows:(1)Change the pattern of argon flow can lower content of oxygen and carbon in CZSi, so that oxygen content reduce to 2×10¹⁷atoms/cm³ and carbon content reduceto 0.3×10¹⁷atoms/cm³;(2)Change the size of heater thermal stove can lower contents of oxygen and carbon in CZSi, spend less time in crystal growth process with less energy consumption and better crystal quality;(3) Crucible of high purity should be high-quality materials, so as to reduce the impurities into the crystal, but in the actual manufacturing process need to consider the cost of general;(4) 40L/min Argon flow in CZSi growth, the oxygen content were significantly lower than the flow of 35L/min, but a slight increase in oxygen content;(5)stacking charge 75kg or 60kg, the changes in oxygen content is not obvious;(6) To the same the speed of crystal rotation, the high grade speed of crucible rotation, can lower contents of oxygen in CZSi carbon content of the tail of the increase in value is very unstable and a serious failure Product; but the high grade speed of crucible and crystal rotation, there was no significant change of carbon and oxygen content.The experimental results show that when the argon flowing upwards, the small-sized thermal field and the high grade crucible are used, the content of carbon and oxygen can be cut down markedly. When the argon current capacity is enlarged, the feeding quantity is increased and the speed of crystal rotation and crucible rotation are adjusted; then content of the carbon and oxygen is reduced, the distribution the carbon and oxygen is improved. Finally the aim of decreasing the carbon content and controlling the oxygen content is achieved. And the contribution is made for silicon chip solar energy conversion efficiency.