# US 8,769,993 B2 · Silicon electromagnetic casting apparatus

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- Number: US 8,769,993 B2
- Document ID: US8769993B2
- Status: Granted
- Kind: B2
- Application number: 13/814,809
- Filed: 2010-11-17
- Published: 2013-05-30
- Granted: 2014-07-08
- Earliest claimed: 2010-08-11
- Assignees: Sumco Corporation
- Applicants: Daisuke Ebi; Mitsuo Yoshihara
- Inventors: Daisuke Ebi; Mitsuo Yoshihara
- Web page: https://patentgrep.com/patent/US8769993B2

## CPC

- B22D 27/04: Influencing the temperature of the metal, e.g. by heating or cooling the mould
- C01B 33/02: Silicon (forming single crystals or homogeneous polycrystalline material with defined structure C30B)
- C30B 11/001: {Continuous growth}
- C30B 29/06: Silicon
- B22D: CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES (shaping of plastics or substances in a plastic state B29C; metallurgical processing, selection of substances to be added to metal C21, C22)
- C01B: NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; {METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C}
- C30B: SINGLE-CRYSTAL GROWTH (by using ultra-high pressure, e.g. for the formation of diamonds, B01J3/06); UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL (zone-refining of metals or alloys C22B); PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE (casting of metals, casting of other substances by the same processes or devices B22D; working of plastics B29; modifying the physical structure of metals or alloys C21D, C22F); SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE (for producing semiconductor devices or parts thereof H10); APPARATUS THEREFOR

## Abstract

Provided is a silicon electromagnetic casting apparatus that is capable of stably producing polycrystalline silicon used as a solar cell substrate material, having a bottomless cold mold and an induction heating coil, the apparatus for pulling down the silicon melted through electromagnetic induction heating by means of the induction coil and solidifying the silicon melt; further including a plasma torch for generating a transferable plasma arc and a top heater configured so as to face a top surface of the molten silicon, the top heater for generating heat through electromagnetic induction by means of the induction coil. The apparatus enables, upon production of a high quality polycrystalline silicon ingot as a solar cell substrate material along with plasma heating, stable production thereof without cracking in a final solidification portion.

## Claims

### Claim 1

A silicon electromagnetic casting apparatus including:
a conductive bottomless cold mold in which part thereof in an axial direction is divided into a plurality of elements along a circumferential direction; and
an induction coil surrounding the mold, in which silicon is melted through electromagnetic induction heating by means of the induction coil and is pulled down to be solidified, and further comprising:
a plasma torch as a heating source installed above the cold mold so as to be raised or lowered, the plasma torch generating a transferable plasma arc in continuous casting; and
a top heater configured so as to face a top surface of the molten silicon in the cold mold, the top heater generating heat through electromagnetic induction by means of the induction coil in a final solidification step at which casting ends, the top heater comprising two or more divided heating members.

### Claim 2 (depends on 1)

The silicon electromagnetic casting apparatus according to claim 1, wherein
the top heater has a structure in which the top heater is suspended from the plasma torch.

### Claim 3 (depends on 2)

The silicon electromagnetic casting apparatus according to claim 2, wherein
the cold mold is a square or rectangular mold having a side length of 300 mm or more.

### Claim 4 (depends on 2)

The silicon electromagnetic casting apparatus according to claim 2, wherein a frequency of an alternating current applied to the induction coil is 25 to 35 kHz.

### Claim 5 (depends on 4)

The silicon electromagnetic casting apparatus according to claim 4, wherein the cold mold is a square or rectangular mold having a side length of 300 mm or more.

### Claim 6 (depends on 1)

The silicon electromagnetic casting apparatus according to claim 1, wherein
a frequency of an alternating current applied to the induction coil is 25 to 35 kHz.

### Claim 7 (depends on 6)

The silicon electromagnetic casting apparatus according to claim 6, wherein
the cold mold is a square or rectangular mold having a side length of 300 mm or more.

### Claim 8 (depends on 1)

The silicon electromagnetic casting apparatus according to claim 1, wherein
the cold mold is a square or rectangular mold having a side length of 300 mm or more.