# US 5,704,974 A · Growth of silicon crystal from melt having extraordinary eddy flows on its surface

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 5,704,974 A
- Document ID: US5704974A
- Status: Granted
- Kind: A
- Application number: 08/620,873
- Filed: 1996-03-22
- Granted: 1998-01-06
- Earliest claimed: 1995-03-24
- Assignees: Research Development Corporation of Japan; Sumitomo Sitix Corporation; Toshiba Ceramics Co., Ltd.; Nippon Steel Corporation; Komatsu Electronic Metals Co., Ltd.; Mitsubishi Materials Corporation
- Inventors: Koji Izunome; Souroku Kawanishi; Shinji Togawa; Atsushi Ikari; Hitoshi Sasaki; Shigeyuki Kimura
- Web page: https://patentgrep.com/patent/US5704974A

## CPC

- C30B 29/06: Silicon
- C30B 15/30: Mechanisms for rotating or moving either the melt or the crystal (flotation methods C30B15/28)
- 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

When a Si single crystal 8 is pulled up from a melt 6 received in a crucible 2, the state of eddy flows generated in the melt 6 is judged from the temperature distribution of the melt at the surface. According to the result of judgement, the gas, i.e. N.sub.2, Xe or Kr, which causes extraoridnary deviation in the density of a melt 6 is added to an atmospheric gas, so as to keep the eddy flows under unstabilized condition. The effect of said gas is typical in the case of crystal growth from the melt to which a dopant such as Ca, Sb, Al, As or In having the effect to suppress the extraordinary deviation in the density is added. Since the single crystal is pulled up from the melt held in the temperature-controlled condition at the surface, impurity distribution and oxygen distribution are made uniform along the direction of crystal growth. A single crystal obtained in this way has highly-stabilized quality.

## Claims

### Claim 1

A method of growing and distinguishing a quality of a Si single crystal from a melt having a surface, comprising the steps of:
detecting a state of eddy flows generated on the surface of the melt received in a crucible from the temperature distribution of the melt at the surface when the single crystal is pulled up from the melt, and
distinguishing the single crystal pulled up from the melt in an unstable vortex state as a high-quality product.

### Claim 2

A method of growing a Si single crystal containing at least one impurity which suppresses a temperature deviation of a melt having a surface, comprising the steps of:
detecting a state of eddy flows generated on the surface of the melt received in a crucible from the temperature distribution of the melt at the surface when the single crystal is pulled up from the melt, and
introducing a gas which causes deviation in the density of the melt into an atmospheric gas in contact with the melt, so as to hold the melt under a condition in which the eddy flows are unstable.

### Claim 3 (depends on 2)

The method according to claim 2, wherein the at least one impurity is selected from the group consisting of Ga, Sb, Al, As and In, which determine the electrical resistivity of the crystal.

### Claim 4

A method of growing a Si single crystal under a condition to suppress a temperature deviation of a melt having a surface, comprising the steps of:
detecting a state of eddy flows generated on the surface of the melt received in a crucible from the temperature distribution of the melt at the surface when the single crystal is pulled up from the melt; and
introducing a gas which causes deviation in the density of the melt into an atmospheric gas in contact with the melt, so as to hold the melt under a condition in which the eddy flows are unstable,
wherein the gas causing the deviation in the density of the melt is at least one of N.sub.2, Kr and Xe.