Methods for producing low oxygen silicon ingots

Patent metadata

Field	Value
Publication number	US-10513796-B2
Application number	US-201815959964-A
Country	US
Kind code	B2
Filing date	Apr 23, 2018
Priority date	May 24, 2013
Publication date	Dec 24, 2019
Grant date	Dec 24, 2019

Abstract

An method for producing a silicon ingot includes melting polycrystalline silicon in a crucible enclosed in a vacuum chamber to form a melt, generating a cusped magnetic field within the vacuum chamber, dipping a seed crystal into the melt, withdrawing the seed crystal from the melt to pull a single crystal that forms the silicon ingot, wherein the silicon ingot has a diameter greater than about 150 millimeters (mm), and simultaneously regulating a plurality of process parameters such that the silicon ingot has an oxygen concentration less than about 5 parts per million atoms (ppma). The plurality of process parameters include a wall temperature of the crucible, a transport of silicon monoxide (SiO) from the crucible to the single crystal, and an evaporation rate of SiO from the melt.

First claim

What is claimed is:

1. A method for producing a silicon ingot, the method comprising:
melting polycrystalline silicon in a crucible enclosed in a vacuum chamber to form a melt;
generating a cusped magnetic field within the vacuum chamber;
dipping a seed crystal into the melt; withdrawing the seed crystal from the melt to pull a single crystal that forms the silicon ingot, wherein the silicon ingot has a diameter greater than about 150 millimeters (mm); and
simultaneously regulating a plurality of process parameters such that the silicon ingot has an oxygen concentration less than about 5 parts per million atoms (ppma), wherein the plurality of process parameters include a wall temperature of the crucible, a transport of silicon monoxide (SiO) from the crucible to the single crystal, and an evaporation rate of SiO from the melt; wherein simultaneously regulating a plurality of process parameters comprises maintaining a melt to reflector gap in a range from approximately 60 mm to 80 mm, and
wherein the silicon ingot has a diameter in a range from approximately 150 mm to 460 mm.

2. A method in accordance with claim 1 , wherein the silicon ingot has a diameter of approximately 300 mm.

3. The method in accordance with claim 1 , wherein simultaneously regulating a plurality of process parameters comprises operating a heater positioned below the crucible.

4. A method in accordance with claim 1 , wherein simultaneously regulating a plurality of process parameters comprises rotating the crucible at a rate in a range from approximately 1.3 rpm to 2.2 rpm.

5. A method in accordance with claim 1 , wherein generating a cusped magnetic field comprises generating a cusped magnetic field having a magnetic field strength in a range from approximately 0.02 to 0.05 Tesla at an edge of the single crystal at a melt-solid interface, and having a magnetic field strength in a range from approximately 0.05 to 0.12 Tesla at a wall of the crucible.

6. A method in accordance with claim 1 , wherein simultaneously regulating a plurality of process parameters comprises flowing argon gas through the vacuum chamber at a flow rate in a range from approximately 100 standard liters per minute (slpm) to 150 slpm.

7. A method in accordance with claim 1 , wherein simultaneously regulating a plurality of process parameters comprises flowing argon gas through the vacuum chamber at a pressure in a range from approximately 10 torr to 30 torr.

8. A method in accordance with claim 1 , wherein the measured defects include less than 400 defects having a size less than 60 nm, less than 100 defects having a size between 60 and 90 nm, and less than 100 defects having a size between 90 and 120 nm.

9. A method in accordance with claim 8 , wherein doping the single crystal comprises doping the single crystal with nitrogen such that a nitrogen concentration is within a range from 0 atoms per cubic centimeter to 8e15 atoms per cubic centimeter.

10. A wafer in accordance with claim 1 , wherein the wafer has 30 ohm-cm to 300 ohm-centimeter N-type resistivity such that the wafer is suitable for use in IGBT applications.

11. A wafer in accordance with claim 1 , wherein the wafer has greater than 750 ohm-cm N/P-type resistivity such that the wafer is suitable for use in IGBT applications.

12. A wafer in accordance with claim 1 , wherein the wafer has greater than 750 ohm-cm P-type resistivity such that the wafer is suitable for use in RF, HR-SOI, and CTL-SOI applications.

13. A wafer in accordance with claim 1 , wherein the wafer is a handle wafer.

14. A wafer in accordance with claim 1 , wherein the wafer is a P-type product having at least one of boron, aluminum, germanium, and indium as a majority carrier, and having at least one of red phosphorus, phosphorus, arsenic, and antimony as a minority carrier.

15. A wafer in accordance with claim 1 , wherein the wafer is a N-type product having at least one red phosphorus, phosphorus, arsenic, and antimony as a majority carrier, and having at least one of boron, aluminum, germanium, and indium as a minority carrier.

16. A method for producing a silicon ingot, the method comprising:
melting polycrystalline silicon in a crucible enclosed in a vacuum chamber to form a melt;
generating a cusped magnetic field within the vacuum chamber;
dipping a seed crystal into the melt; withdrawing the seed crystal from the melt to pull a single crystal that forms the silicon ingot, wherein the silicon ingot has a diameter greater than about 150 millimeters (mm); and
simultaneously regulating a plurality of process parameters such that the silicon ingot has an oxygen concentration less than about 5 parts per million atoms (ppma), wherein the plurality of process parameters include a wall temperature of the crucible, a transport of silicon monoxide (SiO) from the crucible to the single crystal, and an evaporation rate of SiO from the melt; wherein simultaneously regulating a plurality of process parameters comprises positioning a cusp of the generated magnetic field in a range from approximately 10 mm to 40 mm below a surface of the melt, and
wherein the silicon ingot has a diameter in a range from approximately 150 mm to 460 mm.

17. A method in accordance with claim 16 , wherein the silicon ingot has a diameter of approximately 300 mm.

18. The method in accordance with claim 16 , wherein simultaneously regulating a plurality of process parameters comprises operating a heater positioned below the crucible at a power in a range from approximately 0 kilowatts to 5 kilowatts.

19. A method in accordance with claim 16 , wherein simultaneously regulating a plurality of process parameters comprises rotating the crucible at a rate in a range from approximately 1.3 rpm to 2.2 rpm.

20. A method in accordance with claim 16 , wherein generating a cusped magnetic field comprises generating a cusped magnetic field having a magnetic field strength in a range from approximately 0.02 to 0.05 Tesla at an edge of the single crystal at a melt-solid interface, and having a magnetic field strength in a range from approximately 0.05 to 0.12 Tesla at a wall of the crucible.

21. A method in accordance with claim 16 , wherein simultaneously regulating a plurality of process parameters comprises flowing argon gas through the vacuum chamber at a flow rate in a range from approximately 100 standard liters per minute (slpm) to 150 slpm.

22. A method in accordance with claim 16 , wherein simultaneously regulating a plurality of process parameters comprises flowing argon gas through the vacuum chamber at a pressure in a range from approximately 10 torr to 30 torr.

23. A method in accordance with claim 16 , wherein the measured defects include less than 400 defects having a size less than 60 nm, less than 100 defects having a size between 60 and 90 nm, and less than 100 defects having a size between 90 and 120 nm.

24. A method in accordance with claim 23 , wherein doping the single crystal comprises doping the single crystal with nitrogen such that a nitrogen concentration is within a range from 0 atoms per cubic centimeter to 8e15 atoms per cubic centimeter.

25. A method in accordance with claim 16 , wherein simultaneously regulating a plurality of process parameters comprises maintaining a melt to reflector gap in a range from approximately 60 mm to 80 mm.

26. A wafer in accordance with claim 16 , wherein the wafer has 30 ohm-cm to 300 ohm-centimeter N-type re

Assignees

• Globalwafers Co Ltd

Inventors

• Basak Soubir
• Hudson Carissima Marie
• Samanta Gaurab
• Ryu Jae-Woo
• Sreedharamurthy Hariprasad
• Mccallum Kirk D
• Lee Hyungmin

Classifications

• C30B15/305 Primary

  Stirring of the melt · CPC title

• C30B15/30

  Mechanisms for rotating or moving either the melt or the crystal (flotation methods C30B15/28) · CPC title

• C30B15/04

  adding doping materials, e.g. for n-p-junction · CPC title

• C30B30/04

  using magnetic fields · CPC title

• C30B29/06

  Silicon · CPC title