| 摘要 |
PROBLEM TO BE SOLVED: To mold, on an occasion for manufacturing a floating zone (FZ) monocrystal for solar cells, a polycrystalline silicon generally mass-produced based on a zinc reduction method of silicon tetrachloride in a fixed form such as a rod shape, etc. for enabling the use thereof as a raw ingredient for manufacturing the FZ monocrystal, to execute the molding efficiently within the briefest time possible for suppressing the contamination thereof by impurities serving as lifetime killers and originating from a molten liquid interface, and thus to suppress the same at a level 0.01 or less of the same in Czochralski (CZ) monocrystal silicon being generally used today.SOLUTION: For the purpose of molding, as a silicon rod, polycrystalline silicon of an acicular, dendritic, coral, or lumpy shape produced by the zinc reduction method, vacuum suction is performed via a quartz tube plugged into a molten silicon liquid provided as a raw ingredient or a SiC tube impregnated with high-purity silicon, and the liquid contact time is reduced by adjusting the magnitude of vacuum. The solidification time within the suction tube, furthermore, is adjusted by installing a heat ray source or high-frequency coil above the liquid contact interface of the suction tube and by impressing thereon an energy at an adjusted output. It accordingly becomes to ameliorate osmotic contaminations by lifetime killers at negligible levels. |
