# US 5,704,973 A · Apparatus and method for the uniform distribution of crystal defects upon a silicon single crystal

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- Number: US 5,704,973 A
- Document ID: US5704973A
- Status: Granted
- Kind: A
- Application number: 08/666,654
- Filed: 1996-06-18
- Granted: 1998-01-06
- Earliest claimed: 1995-06-20
- Assignees: Shin-Etsu Handotai Co., Ltd.
- Inventors: Masahiro Sakurada; Wataru Sato; Tomohiko Ohta
- Web page: https://patentgrep.com/patent/US5704973A

## CPC

- C30B 29/06: Silicon
- C30B 15/00: Single-crystal growth by pulling from a melt, e.g. Czochralski method (under a protective fluid C30B27/00)
- Y10T 117/1032: Seed pulling
- 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

Proposed is an improvement in the method and single crystal growing chamber for the preparation of a single crystal rod of silicon by the Czochralski method, according to which the distance between the surface of the melt of silicon contained in a crucible and the lower surface of the top wall of the crystal growing chamber is equal to or larger than the diameter of the crucible and the heat-insulating cylinder surrounding the crucible containing the melt of silicon and the heater has such a height as to reach the lower surface of the top wall of the chamber so as to keep the single crystal rod under growing is kept at a temperature not lower than 700.degree. C. until reaching the lower surface of the top wall of the chamber thereby decreasing the density of the crystal defects of BMD type in the seed end of the single crystal rod as grown so that the uniformity in the distribution of BMD density is increased throughout the single crystal rod.

## Claims

### Claim 1

In a method for the preparation of a silicon single crystal rod by the Czochralski method, the improvement which comprises keeping the length of time taken by a silicon single crystal rod under the process of growth to pass through a region where the temperature is in a range from 600.degree. C. to 700.degree. C. does not exceed 80 minutes.

### Claim 2

In a method for the preparation of a silicon single crystal rod by the Czochralski method from a melt of silicon contained in a crucible held in a crystal growing chamber, the improvement which comprises keeping the single crystal rod under growth leaving the surface of the melt until reaching the lower surface of the top wall of the crystal growing chamber at a temperature of 700.degree. C. or higher.

### Claim 3

In a method for the preparation of a silicon single crystal rod by the Czochralski method from a melt of silicon contained in a crucible held in a crystal growing chamber, the improvement which comprises keeping a distance between the surface of the melt of silicon contained in a crucible and the lower surface of the top wall of the crystal growing chamber to be equal to or larger than the diameter of the crucible and keeping the single crystal rod under growth leaving the surface of the melt of silicon until reaching the lower surface of the top wall of the crystal growing chamber at a tem-perature of 700.degree. C. or higher.

### Claim 4

In a single crystal growing chamber for the preparation of a single crystal rod of silicon by the Czochralski method from a melt of silicon contained in a crucible heated by means of a heater, the improvement which comprises that a heat-insulating cylinder, which surrounds the crucible containing the melt of silicon and the heater to melt the silicon in the crucible, is provided, the heat-insulating cylinder having such a height as to reach a lower surface of a top wall of the crystal growing chamber.

### Claim 5

In a single crystal growing chamber for the preparation of a single crystal rod of silicon by the Czochralski method from a melt of silicon contained in a crucible heated by means of a heater, the improvement which comprises that the distance between the surface of a melt of silicon contained in the crucible and the lower surface of the top wall of the crystal growing chamber is equal to or larger than the diameter of the crucible and a heat-insulating cylinder, which surrounds the crucible containing the melt of silicon and the heater to melt the silicon in the crucible, is provided, the the heat-insulating cylinder having such a height as to reach the lower surface of the top wall of the crystal growing chamber.

### Claim 6

In a single crystal growing chamber for a preparation of a single crystal rod of silicon by the Czochralski method from a melt of silicon contained in a crucible heated by means of a heater, the improvement which comprises that a heat-insulating cylinder, which surrounds the crucible containing the melt of silicon and a heater to melt the silicon in the crucible, is provided, the heat-insulating cylinder having such a height as to reach a lower surface of the top wall of the crystal growing chamber so as to keep a region between a surface of the melt of silicon contained in the crucible and the lower surface of the top wall of the chamber at a temperature of 700.degree. C. or higher.

### Claim 7

In a single crystal growing chamber for the preparation of a single crystal rod of silicon by the Czochralski method from a melt of silicon contained in a crucible heated by means of a heater, the improvement which comprises that the distance between a surface of the melt of silicon contained in the crucible and a lower surface of a top wall of the crystal growing chamber is equal to or larger than the diameter of the crucible and a heat-insulating cylinder, which surrounds the crucible containing the melt of silicon and the heater to melt the silicon in the crucible, is provided, the heat-insulating cylinder having such a height as to reach the lower surface of the top wall of the crystal growing chamber so as to keep a region between the surface of the melt of silicon contained in the crucible and the lower surface of the top wall of the chamber at a temperature of 700.degree. C. or higher.