Flow rate control device and its flow rate control method of inert gas of a silicon single crystal pulling apparatus

摘要

PROBLEM TO BE SOLVED: To enlarge the defect-free, high quality part of an ingot in the longitudinal direction.;SOLUTION: The lower end of the cylindrical part 37 of a heat insulating member 36 surrounding the outer circumferential surface of the ingot 25 is positioned above the surface of a silicon molten liquid 12 leaving a certain interval, a swelled part 41 is provided in the lower end inside the cylindrical part 37, and an inert gas supply and exhaust means makes an inert gas flow down between the swelled part 41 and the ingot 25. A plurality of flow straightening plates 43 which are respectively provided to vertically extend between the outer circumferential surface of the ingot 25 and the inner circumferential surface of the swelled part 41 and to freely move in parallel in the radial direction of the ingot 25 surround the outer circumferential surface of the ingot 25. A plurality of control plates 47 having respective base ends attached to the swelled part 41 and respective tip parts attached pivotally to the respective upper ends of a plurality of the flow straightening plates 43 close the gap between a plurality of the flow straightening plates 43 and the swelled part 41. The plurality of control plates 47 are respectively driven by a control plate driving means 50 in accordance with the change of the convection 12b of the silicon molten liquid 12 to control the solid-liquid boundary face 12c to be in an upward convex state.;COPYRIGHT: (C)2004,JPO