# US 5,700,320 A · Growth of silicon single crystal having uniform impurity distribution along lengthwise or radial direction

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- Number: US 5,700,320 A
- Document ID: US5700320A
- Status: Granted
- Kind: A
- Application number: 08/620,391
- Filed: 1996-03-22
- Granted: 1997-12-23
- 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/US5700320A

## 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)
- 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 B or P-doped Si single crystal is pulled up from a B or P-doped melt by the Czochralski method, an element such as Ga, Sb or In having the effect to reduce the heat expansion coefficient of said melt at a temperature near the melting point is added to said melt. The additive element stabilizes the temperature condition of crystal growth so as to control the generation of eddy flows just below the interface of crystal growth. When a Ga or Sb-doped Si single crystal is pulled up from a Ga or Sb-doped melt, an element such as B or P having the effect to increase the heat expansion coefficient of said melt at a temperature near the melting point is added. The agitation of the melt just below the interface of crystal growth is accelerated by the addition of B or P, so as to assure the growth of a Si single crystal from the melt having impurity distribution made uniform along the radial direction. Accordingly, a Si single crystal is formed having a uniform impurity distribution along its lengthwise or radial direction.

## Claims

### Claim 1

A method of pulling up an at least one of B and P-doped Si single crystal from a melt, comprising the steps of:
preparing an at least one of B and P-doped Si melt,
adding an element to reduce a heat expansion coefficient of said melt to said melt, and
pulling up a Si single crystal from said melt, whereby an impurity distribution of said single crystal is substantially uniform along a direction of crystal growth.

### Claim 2 (depends on 1)

The method according to claim 1, wherein the element to reduce the heat expansion coefficient is at least one of Ga, Sb and In.

### Claim 3

A method of pulling up an at least one of Ga and Sb-doped Si single crystal from a melt, comprising the steps of:
preparing an at least one of Ga and Sb-doped Si melt,
adding an element to increase a heat expansion coefficient of said melt to said melt, and
pulling up a Si single crystal from said melt, whereby an impurity distribution of said single crystal is made substantially uniform along a radial direction of the crystal.

### Claim 4 (depends on 3)

The method according to claim 3, wherein the element to increase the heat expansion coefficient is at least one of B and P.