Apparatus and method for neutron transmutation doping of semiconductor wafers

Patent metadata

Field	Value
Publication number	US-10468148-B2
Application number	US-201715494599-A
Country	US
Kind code	B2
Filing date	Apr 24, 2017
Priority date	Apr 24, 2017
Publication date	Nov 5, 2019
Grant date	Nov 5, 2019

Abstract

In various embodiments, a method of processing one or more semiconductor wafers is provided. The method includes positioning the one or more semiconductor wafers in an irradiation chamber, generating a neutron flux in a spallation chamber coupled to the irradiation chamber, moderating the neutron flux to produce a thermal neutron flux, and exposing the one or more semiconductor wafers to the thermal neutron flux to thereby induce the creation of dopant atoms in the one or more semiconductor wafers.

First claim

What is claimed is:

1. A method of processing one or more semiconductor wafers, the method comprising:
positioning the one or more semiconductor wafers in an irradiation chamber;
generating a neutron flux in a spallation chamber coupled to the irradiation chamber;
moderating the neutron flux to produce a thermal neutron flux; and
exposing the one or more semiconductor wafers to the thermal neutron flux to thereby induce the creation of dopant atoms in the one or more semiconductor wafers,
wherein the one or more semiconductor wafers comprise a plurality of semiconductor wafers,
wherein each of the plurality of semiconductor wafers has a first surface and a second surface opposite the first surface,
wherein the plurality of semiconductor wafers are positioned so that the first and second surfaces of each semiconductor wafer are perpendicular to the thermal neutron flux and the thermal neutron flux flows through the plurality of semiconductor wafers and is incident on the first surface of each of the plurality of semiconductor wafers, and
wherein the plurality of semiconductor wafers are positioned to be collinear with each other so that a first surface of one semiconductor wafer faces a second surface of another semiconductor wafer.

2. The method of claim 1 , wherein the generating the neutron flux comprises:
generating a proton beam; and
directing the proton beam at a neutron producing target to thereby generate the neutron flux.

3. The method of claim 2 , wherein the generating the proton beam comprises:
directing a laser beam at a proton producing target to thereby generate the proton beam.

4. The method of claim 2 , further comprising:
cooling the neutron producing target.

5. The method of claim 2 , further comprising:
monitoring the thermal neutron flux in the irradiation chamber.

6. The method of claim 2 , further comprising:
cladding the plurality of semiconductor wafers with an oxide material before exposure to the thermal neutron flux and uncladding the oxide material from the plurality of semiconductor wafers after exposure to the thermal neutron flux.

7. The method of claim 2 , further comprising:
annealing the plurality of semiconductor wafers.

8. The method of claim 2 , further comprising:
removing spallated particles adjacent to a surface of the neutron producing target on which the proton beam is incident.

9. The method of claim 2 ,
wherein the proton beam is generated from a particle accelerator.

10. The method of claim 2 ,
wherein the neutron producing target comprises lithium, lithium/carbon mixture, tungsten, boron, or boron compounds.

11. The method of claim 2 ,
wherein the neutron flux is moderated by heavy water, carbon, or carbon compounds.

12. The method of claim 2 ,
wherein each of the plurality of semiconductor wafers has a diameter of about 300 mm or greater.

13. The method of claim 1 ,
wherein the irradiation chamber and the spallation chamber each comprise a cylindrical cavity, and
wherein the plurality of semiconductor wafers are axially aligned with the cylindrical cavity of the irradiation chamber.

14. The method of claim 13 ,
wherein the spallation chamber and the irradiation chamber are axially aligned with each other.

15. The method of claim 1 , further comprising:
repositioning the plurality of semiconductor wafers after a first exposure period so that the thermal neutron flux is incident on the second surface of each of the plurality of semiconductor wafers for a second exposure period.

16. The method of claim 15 ,
wherein the plurality of semiconductor wafers are arranged on a removable wafer rack in the irradiation chamber, further comprising:
removing after the first exposure period the removable wafer rack from the irradiation chamber; and
repositioning the removable wafer rack in the irradiation chamber so that an orientation of the removable wafer rack is reversed for the second exposure period.

17. The method of claim 16 ,
wherein the irradiation chamber comprises a single cavity for receiving the plurality of semiconductor wafers and a door for accessing the cavity.

18. The method of claim 1 ,
wherein the moderating is performed by a neutron moderator disposed between the spallation chamber and the irradiation chamber so as to partition the spallation chamber and irradiation chamber.

19. The method of claim 18 ,
wherein the spallation chamber and the irradiation chamber each comprise neutron reflective walls, further comprising:
guiding neutrons of the neutron flux in the spallation chamber towards the irradiation chamber and guiding neutrons of the thermal neutron flux in the irradiation chamber towards the plurality of semiconductor wafers.

Assignees

• Infineon Technologies Ag

Inventors

• Bina Markus
• Schulze Hans-Joachim
• Schustereder Werner

Classifications

• H10P34/20

  for inducing a nuclear reaction transmuting chemical elements · CPC title

• G21G1/06 Primary

  by neutron irradiation · CPC title

• G21G4/02

  Neutron sources · CPC title

• C30B31/20

  Doping by irradiation with electromagnetic waves or by particle radiation · CPC title

• H01L21/261

  Electricity · mapped topic