# US 5,707,447 A · Crystal pulling apparatus

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- Number: US 5,707,447 A
- Document ID: US5707447A
- Status: Granted
- Kind: A
- Application number: 08/718,965
- Filed: 1996-09-26
- Granted: 1998-01-13
- Earliest claimed: 1995-09-26
- Assignees: Balzers und Leybold Deutschland Holding AG
- Inventors: Winfried Schulmann; Johann Scholler
- Web page: https://patentgrep.com/patent/US5707447A

## CPC

- C30B 15/14: Heating of the melt or the crystallised materials
- Y10T 117/1032: Seed pulling
- Y10T 117/1068: including heating or cooling details [e.g., shield configuration]
- Y10T 117/1088: including heating or cooling details
- 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
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

A crystal pulling apparatus for producing a crystal boule (17) from a material melted in a crucible (4) has, in a tank (1), a heater (5) surrounding the crucible (4). The tank (1) has in the area of the crucible (4) an annular chamber (8) defined on the heater (5) side by an inner protective wall (6) and connected to the shielding gas outlet (14, 15), and on the outside by an outer protective wall (7) behind which the thermal insulation (10) of the tank (1) is located.

## Claims

### Claim 1

A crystal pulling apparatus for producing a crystal boule from a melted material, said apparatus comprising
a crucible for containing said melted material,
a heater surrounding said crucible,
a tank in which said crucible and said heater are located, said tank being provided with thermal insulation and cooling passages externally of said insulation, and provided with thermal insulation and cooling passages externally of said insulation, and an annular chamber between said heater and said insulation, said chamber being defined by an inner wall adjacent to said heater and an outer wall adjacent to said insulation, and
at least one shielding gas outlet connected to said annular chamber.

### Claim 2 (depends on 1)

A crystal pulling apparatus as in claim 1 wherein said annular chamber comprises a bottom and provided with a screen plate, said at least one shielding gas outlet being connected to said annular chamber through said screen plate.

### Claim 3 (depends on 1)

A crystal pulling apparatus as in claim 1 wherein said tank comprises a floor in which two said shielding gas outlets are located, said outlets being axially aligned with said tank and opposite one another.

### Claim 4 (depends on 1)

A crystal pulling apparatus as in claim 1 wherein said heater has an upper edge and said inner wall extends upward to said upper edge of said heater.