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US-20260125820-A1 - PROCESS FOR MANUFACTURING A SILICON SINGLE CRYSTAL, AND SEMICONDUCTOR WAFER MADE OF SINGLE-CRYSTAL SILICON

US20260125820A1US 20260125820 A1US20260125820 A1US 20260125820A1US-20260125820-A1

Abstract

A method produces a single crystal of silicon by pulling the single crystal from a melt. The melt is in a crucible and includes phosphorus and boron as dopants in a ratio of not more than 0.41. The boron is in the melt with a concentration of 5.0×10 14 to 2.2×10 15 atoms/cm 3 . The single crystal has a cylindrical section having a diameter of at least 300 mm, which is surrounded by a heat shield while pulled from the melt. A lower edge of the heat shield is further than 18 mm from a melt surface. The single crystal is pulled at 8-13 rpm. A horizontal magnetic field is also applied to the melt, with a magnetic flux density of the horizontal magnetic of 2000-3000 Gs.

Inventors

  • Walter Heuwieser
  • Karl Mangelberger

Assignees

  • SILTRONIC AG

Dates

Publication Date
20260507
Application Date
20230929
Priority Date
20221006

Claims (6)

  1. 1 . A method of producing a single crystal of silicon, the method comprising: pulling the single crystal from a melt, the melt being present in a crucible and comprising phosphorus and boron as dopants in a ratio of not more than 0.41, the boron being in the melt with a concentration of not less than 5.0×10 14 atoms/cm 3 and not more than 2.2×10 15 atoms/cm 3 , and the single crystal having a cylindrical section having a diameter of at least 300 mm, having a length, and being surrounded by a heat shield in a course of the pulling the single crystal from the melt, and a lower edge of the heat shield having a distance of not less than 18 mm from a surface of the melt, the pulling of the single crystal being at a speed of not less than 8 rpm and not more than 13 rpm; and applying a horizontal magnetic field to the melt, a magnetic flux density of the horizontal magnetic field being not less than 2000 Gs and not more than 3000 Gs.
  2. 2 . The method according to claim 1 , wherein the length is at least 1500 mm.
  3. 3 . The method according to claim 1 , wherein the ratio is not greater than 0.35 and not less than 0.1.
  4. 4 . The method according to claim 1 , wherein the distance is 19 mm to 25 mm.
  5. 5 . A semiconductor wafer of monocrystalline silicon having a diameter of at least 300 mm, the semiconductor wafer being predominantly p-doped, the semiconductor wafer comprising phosphorus and boron as dopants, wherein a specific electrical resistance from a center up to an edge of the semiconductor wafer varies by not more than 1%, based on a smallest resistance, and taking account of an edge exclusion of 6 mm.
  6. 6 . The semiconductor wafer according to claim 5 , wherein the specific electrical resistance is not less than 6 Ohmcm and not more than 30 Ohmcm.

Description

CROSS REFERENCE TO RELATED APPLICATIONS This application is a U.S. National Phase application under 35 U.S.C. § 371 of International Application No. PCT/EP2023/077145, filed on Sep. 29, 2023, and claims benefit to European Patent Application No. EP 22199997.2, filed on Oct. 6, 2022. The International Application was published in German on Apr. 11, 2024 as WO 2024/074431 A1 under PCT Article 21(2). FIELD The present disclosure is directed to a method of producing a single crystal of silicon by pulling the single crystal from a melt. The present disclosure is also directed to providing a semiconductor wafer of monocrystalline silicon. BACKGROUND The pulling of a single crystal of silicon from a melt by the Czochralski method comprises the pulling of a cylindrical section with uniform diameter. In general, semiconductor wafers of monocrystalline silicon are divided therefrom. In order to avoid decreasing specific electrical resistance of a single crystal of silicon doped with boron owing to the segregation of boron with the length of the single crystal, counter-doping with phosphorus is possible. US 2005 0 252 442 A1 describes a method of producing a single crystal of silicon, wherein the single crystal is pulled from a melt which is present in a crucible and contains phosphorus and boron as dopants in a ratio of 0.31, and wherein the single crystal is predominantly p-doped and has a cylindrical section having a diameter of about 200 mm. Just as important as the observance of a target resistance over the length of the cylindrical section of the single crystal is that the resistance from the center up to the edge of the single crystal at any length position over the cylindrical section differs to a minimum degree from the target resistance. EP 2 607 526 A1 describes a method of producing a single crystal of silicon, wherein the single crystal is pulled from a melt which is present in a crucible and contains phosphorus and boron as dopants in a ratio of 0.42, and wherein the single crystal is predominantly p-doped and has a cylindrical section having a diameter of about 200 mm. The radial variation of the resistance is 1.5% based on the greatest resistance measured. SUMMARY In an embodiment, the present disclosure provides a method that produces a single crystal of silicon. The method includes: pulling the single crystal from a melt. The melt is present in a crucible and includes phosphorus and boron as dopants in a ratio of not more than 0.41. The boron is in the melt with a concentration of not less than 5.0×1014 atoms/cm3 and not more than 2.2×1015 atoms/cm3. The single crystal has a cylindrical section having a diameter of at least 300 mm, having a length, and being surrounded by a heat shield in a course of the pulling the single crystal from the melt. A lower edge of the heat shield has a distance of not less than 18 mm from a surface of the melt. The pulling of the single crystal is at a speed of not less than 8 rpm and not more than 13 rpm. The method also includes applying a horizontal magnetic field to the melt, the magnetic flux density of the horizontal magnetic field being not less than 2000 Gs and not more than 3000 Gs. BRIEF DESCRIPTION OF THE DRAWINGS Subject matter of the present disclosure will be described in even greater detail below based on the exemplary figures. All features described and/or illustrated herein can be used alone or combined in different combinations. The features and advantages of various embodiments will become apparent by reading the following detailed description with reference to the attached drawings, which illustrate the following: FIG. 1 shows an apparatus suitable for performance of a method according to an aspect of the present disclosure; FIG. 2 shows the progression of the specific electrical resistance relative to the average resistance at the start of the cylindrical section depending on the crystallized amount (FS) of silicon in the case of an example and a counterexample; and FIG. 3 shows the radial variation of the specific electrical resistance as a function of the crystallized amount of silicon in the case of the example and the counter example. DETAILED DESCRIPTION Aspects of the present disclosure are directed to providing, for relatively large and relatively long single crystals of silicon, minimum variation in the specific electrical resistance thereof in the cylindrical section in axial and radial direction. An aspect of the present disclosure is directed to a method of producing a single crystal of silicon by pulling the single crystal from a melt which is present in a crucible and comprises phosphorus and boron as dopants in a ratio of not more than 0.41, wherein the melt comprises boron with a concentration of not less than 5.0×1014 atoms/cm3 and not more than 2.2×1015 atoms/cm3, and the single crystal has a cylindrical section having a diameter of at least 300 mm and a length and is surrounded by a heat shield in the course of pulling from the mel