US 4,830,703 A · Single crystal growth apparatus

Abstract

A pair of coils are arranged to surround a crucible for storing a melt. The axes of the coils are vertical and the melt is heated by a heater. When the coils are energized such that the magnetic fluxes thereof oppose each other along the axial direction, a magnetic field having an isomagnetic field distribution of an elliptical shape is formed. When the energization current is properly selected, a magnetic field for restricting thermal convection of the upper melt portion is formed, while, conversely, thermal convection of the lower melt portion occurs. When the melt surface level is lowered upon pulling of the single crystal, a magnetic field is controlled such that the boundary between the thermal convection restriction region and the thermal convection region is, similarly, lowered. Since thermal convection is restricted near the solid-liquid interface layer, the single crystal can be stably grown. In the lower melt portion, thermal convection is present such that the lower melt is stirred. The temperature of the melt is uniform, thereby manufacturing a uniform single crystal ingot of high quality.

Claims15

Dependent claims

A single crystal growing method comprising the steps of:

dipping a seed crystal in a single crystal material melt stored in a vessel and heated by heating means;
pulling a single crystal growing in a solid-liquid interface layer in the melt;
forming a first magnetic field having an intensity for preventing thermal convection in an upper melt portion, and a second magnetic field having an intensity which does not prevent thermal convection in a lower melt portion, by a pair of coils whose axes are aligned with each other, said axes extending vertically, each of said coils lying in a respective substantially horizontal plane, one above the other each of the magnetic fields having isomagnetic field distribution curves of a circular or elliptical shape in a plane including the axes of said coils;
and
moving a boundary between the first and second magnetic field regions downward upon the downward shift of a surface of the melt.

2 more elements

A single crystal growth apparatus comprising:

a vessel for holding a single crystal material melt;
heating means for heating the melt in said vessel;
a single crystal puller for dipping a seed crystal in the melt and for pulling a single crystal growing in a solid-liquid interface layer in the melt;
magnetic field forming means including a pair of coils whose axes are aligned with each other, said axes extending vertically, each of said coils lying in a respective substantially horizontal plane, one above the other and energizing means for energizing said pair of coils so as to generate opposing magnetic fluxes along an axial direction of said coils, thereby applying a first magnetic field having an intensity for preventing thermal convection in an upper melt portion and a second magnetic field having an intensity which does not prevent thermal convection in a lower melt portion, each of the magnetic fields having isomagnetic field distribution curves of a circular or elliptical shape in a plane including the axes of said coils;
and
magnetic field adjusting means for moving a boundary between the first and second magnetic regions downward upon the downward shift of a surface of the melt.

3 more elements

Dependencies are inferred from the claim text.

Single crystal growth apparatus

Life of this patent

Single crystal growth apparatus

Life of this patent

Abstract

Claims15