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PHYSICAL CHEMISTRY ON THE REFINING OF SOLAR GRADE SILICON USING THE AL-SI SOLVENT

铝硅溶剂精炼太阳能级硅的物理化学

基本信息

批准号：
15360398
负责人：
MORITA Kazuki
金额：
$ 9.73万
依托单位：
THE UNIVERSITY OF TOKYO
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2005
项目状态：
已结题

项目摘要

In the project, physical chemistry of SOG-Si refining using the Al-Si solvent aiming at the establishment of its low cost production process. In prior to the optimization of the solvent composition, solid solubility of Al in the solid Si was precisely determined by TGZM method at 1016 - 1622 K, showing quantitatively that the addition of Cu was effective for the reduction in the Al contamination during the solidification refining due to the strong interaction between Al and Cu.Then the possibility of P and B removal with such solvents was assessed. Considerable removal of P and B was clarified through the solid solubility of P and B determined by TGZM together with the partition ratios of them between solid Si and Si-Al solvent at 1273 - 1673 K. In the case of B bearing system, equilibria between borides and Si-Al melts as well as thermodynamic properties of AlB_<12> solid solution were clarified. Furthermore, Ti addition was found to be significantly effective for the removal of boron due to the ultra low solubility product of TiB_2 in molten Al-Si.Then, the removal of several impurities by the solidification method was assessed. Equilibrium partition ratios of them between solid Si and Al-Si melts were smaller than those for pure Si, which indicated that the recommended process was favorable also from the standpoint of the refining efficiency. Finally, small scale solidification tests were conducted and the utilization of electromagnetic force was found to be effective to recover the primary crystal of Si precipitation in the Al-Si melts. Based on the present results, a low cost refining process for SOG-Si was proposed.

本课题以建立低成本的铝硅溶剂法SOG硅精炼工艺为目标，对SOG硅精炼过程进行了物理化学研究。在优化溶剂组成之前，采用TGZM法在1016 ~ 1622 K范围内精确测定了Al在固态Si中的固溶度，定量表明Cu的加入对降低凝固精炼过程中Al的污染是有效的，这是由于Al和Cu之间的强相互作用，并评估了用这种溶剂去除P和B的可能性。用TGZM测定了1273 ~ 1673 K时P、B的固溶度和在固体Si和Si-Al溶剂中的分配比，结果表明，P、B的去除效果显著。在含B体系中，阐明了硼化物与Si-Al熔体之间的平衡以及Al B_固溶体的热力学性质<12>。此外，由于TiB_2在Al-Si熔体中的溶度积极低，Ti的加入对硼的去除有显著的效果。它们在固体Si和Al-Si熔体之间的平衡分配比小于纯Si的平衡分配比，这表明从精炼效率的角度来看，推荐的工艺也是有利的。最后，进行了小型凝固试验，发现利用电磁力可以有效地恢复铝硅熔体中硅沉淀的初晶。在此基础上，提出了一种低成本的SOG硅精炼工艺。