# US 7,071,079 B2 · Epitaxial wafer and a method for producing it

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- Number: US 7,071,079 B2
- Document ID: US7071079B2
- Status: Granted
- Kind: B2
- Application number: 10/487,043
- Filed: 2002-08-21
- Published: 2004-09-16
- Granted: 2006-07-04
- Earliest claimed: 2001-08-23
- Assignees: Shin-Etsu Handotai Co., Ltd.
- Inventors: Satoshi Tobe
- Web page: https://patentgrep.com/patent/US7071079B2

## CPC

- H10P 36/20: Intrinsic gettering, i.e. thermally inducing defects by using oxygen present in the silicon body
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10

## Abstract

The present invention provides an epitaxial wafer wherein a silicon epitaxial layer is formed on a surface of a silicon single crystal wafer in which nitrogen is doped, and a density of oxide precipitates having such a size that a gettering capability can be achieved in a bulk is 108 numbers/cm3 or more. And the present invention also provides a method for producing an epitaxial wafer wherein a silicon single crystal in which nitrogen is doped is pulled by Czochralski method, the silicon single crystal is processed into a wafer to produce a silicon single crystal wafer, and the silicon single crystal wafer is subjected to heat treatment so that a density of oxide precipitates having such a size that a gettering capability can be achieved in a bulk of the wafer may be 108 numbers/cm3 or more, and then the silicon single crystal wafer is subjected to epitaxial growth. A silicon single crystal wafer which surely has a high gettering capability irrespective of a device process can be obtained herewith.

## Claims

### Claim 1

A method for producing an epitaxial wafer, comprising:
pulling a silicon single crystal, in which nitrogen is doped to a concentration of 1013 to 1014 atoms/cm3, by Czochralski method,
processing the silicon single crystal into a wafer to produce a silicon single crystal wafer,
subjecting the silicon single crystal wafer to a two-stage heat treatment so that a density of oxide precipitates having such a size that a gettering capability can be achieved in bulk of the wafer may be 108/cm3 or more, the two-stage heat treatment consisting of:
heating the silicon single crystal wafer at 600° C.–1000° C. for 0.5 hours to 8 hours, and
subsequently heating the silicon single crystal wafer at 800° C.–1150° C. for 0 hour to 10 hours; and
subjecting the silicon single crystal wafer to epitaxial growth.