High rate magnetic annealing system and method of operating

Patent metadata

Field	Value
Publication number	US-9822424-B2
Application number	US-201514752271-A
Country	US
Kind code	B2
Filing date	Jun 26, 2015
Priority date	Dec 17, 2014
Publication date	Nov 21, 2017
Grant date	Nov 21, 2017

Abstract

An annealing system and method of operating is described. The annealing system includes a furnace having a vacuum chamber wall that defines a processing space into which a plurality of workpieces may be translated and subjected to thermal and magnetic processing, wherein the furnace further includes a heating element assembly having at least one heating element located radially inward from the vacuum chamber wall and immersed within an outer region of the processing space, and wherein the heating element is composed of a non-metallic, anti-magnetic material. The annealing system further includes a magnet system arranged outside the vacuum chamber wall of the furnace, and configured to generate a magnetic field within the processing space.

First claim

The invention claimed is:

1. A magnetic annealing system, comprising:
a furnace comprising a vacuum chamber wall that defines a processing space into which a plurality of workpieces may be translated and subjected to thermal and magnetic processing, the furnace further comprising a heating element assembly including at least one heating element located radially inward from the vacuum chamber wall and immersed within an outer region of the processing space, wherein the heating element is composed of a non-metallic, anti-magnetic material; and
a magnet system arranged outside the vacuum chamber wall of the furnace, and configured to generate a magnetic field within the processing space.

2. The system of claim 1 , wherein the heating element is composed primarily of carbon (C).

3. The system of claim 1 , wherein the furnace is oriented in a horizontal configuration such that workpieces are translated horizontally into and out of the furnace, or wherein the furnace is oriented in a vertical configuration such that workpieces are translated vertically into and out of the furnace.

4. The system of claim 1 , further comprising:
a workpiece boat for carrying the plurality of workpieces; and
a boat loader operably configured to translate the workpiece boat and position the workpieces within the processing space.

5. The system of claim 4 , wherein the system includes at least two workpiece boats each carrying a plurality of wafers, wherein the furnace is a vertical furnace, and workpiece boats are transferred vertically into and out of the vertical furnace by the boat loader, the system further comprising:
a workpiece boat turntable arranged adjacent the vertical furnace, and configured to support the at least two workpiece boats, wherein the workpiece boat turntable includes a load/unload position at which a workpiece boat is loaded onto the workpiece boat turntable prior to processing and from which a workpiece boat is unloaded from the workpiece boat turntable after processing, the workpiece boat turntable further including a process position at which the boat loader transfers a workpiece boat between the workpiece boat turntable and the vertical furnace, wherein the workpiece boat turntable is configured to rotate to index workpiece boats between the process position and the load/unload position, and wherein the workpiece boat turntable includes an opening at the process position to permit the boat loader to engage and translate workpiece boats into and out of the vertical furnace.

6. The system of claim 4 , wherein the heating assembly is disposed in a vacuum during processing, and wherein the heating assembly directly faces a workpiece boat loaded in the furnace during processing without a process tube between the heating assembly and the workpiece boat.

7. The system of claim 1 , wherein the heating element comprises a carbon element sheathed within a protective casing.

8. The system of claim 1 , wherein the vacuum chamber wall is composed of stainless steel, and at least a portion of an inner surface of the vacuum chamber wall has a reflectance that is equal to or greater than 50%.

9. The system of claim 1 , further comprising:
a controller operably coupled to the furnace and the magnet system, and programmably configured to operate a power supply coupled to the at least one heating element.

10. The system of claim 9 , wherein the controller programmably operates the power supply to achieve workpiece heating rates ranging from about 10° C. per minute to about 100° C. per minute.

11. The system of claim 9 , wherein the controller programmably operates the power supply to achieve workpiece cooling rates ranging from about 5° C. per minute to about 20° C. per minute.

12. The system of claim 1 , wherein the magnet system includes an electromagnet or a permanent magnet.

13. The system of claim 1 , wherein the magnet system includes a solenoid magnet or a Helmholtz magnet.

14. The system of claim 1 , wherein the magnet system includes a superconducting magnet.

15. The system of claim 1 , wherein the magnet system generates a magnetic field within the processing space having a magnetic field strength ranging up to 10 Tesla.

16. A method of operating a magnetic annealing system, comprising:
loading a plurality of workpieces into a first workpiece boat;
translating the first workpiece boat into a processing space of a furnace using a boat loader, wherein the processing space is defined within a vacuum chamber wall and the furnace comprises a heating element assembly positioned inside of the vacuum chamber wall, the heating assembly including at least one heating element surrounding the first workpiece boat, wherein the heating element is composed of a non-metallic, anti-magnetic material, and wherein after translating the first workpiece boat into the processing space the heating assembly is positioned between the workpiece boat and the vacuum chamber wall;
elevating a temperature of the plurality of workpieces by coupling power to the heating element assembly;
generating a magnetic field within the processing space using a magnet system arranged outside the furnace; and
wherein the plurality of workpieces and the heating assembly are maintained in a vacuum pressure within the vacuum chamber wall during at least part of the elevating of the temperature or the generating the magnetic field.

17. The method of claim 16 , wherein the heating element is composed primarily of carbon (C).

18. The method of claim 16 , further comprising:
positioning the plurality of workpieces with respect to the at least one heating element such that the plurality of workpieces are in direct line-of-sight with the at least one heating element in the processing space.

19. The method of claim 16 , further comprising:
heating the plurality of workpieces at a rate ranging from about 10° C. per minute to about 100° C. per minute; and
cooling the plurality of workpieces at a rate ranging from about 5° C. per minute to about 20° C. per minute.

20. The system of claim 1 , wherein the furnace is a vertical furnace, the system further including a boat loader for loading and unloading workpiece boats to and from the vertical furnace and workpiece boats are transferred vertically into and out of the vertical furnace by the boat loader, the system further comprising:
a workpiece boat turntable arranged below the vertical furnace, and configured to support at least two workpiece boats, wherein the workpiece boat turntable includes a load/unload position at which a workpiece boat is loaded onto the workpiece boat turntable prior to processing and from which a workpiece boat is unloaded from the workpiece boat turntable after processing, the workpiece boat turntable further including a process position at which the boat loader transfers a workpiece boat between the workpiece boat turntable and the vertical furnace, and wherein the workpiece boat turntable is configured to rotate to index workpiece boats between the process position and the load/unload position, and wherein the workpiece boat turntable includes an opening at the process position to permit the boat loader to engage and translate workpiece boats into and out of the vertical furnace.

Assignees

• Tokyo Electron Ltd

Inventors

• Ishii Toru
• Yamazaki Mitsuru

Classifications

• C21D9/00

  Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor · CPC title

• H01F41/304

  using temporary decoupling, e.g. involving blocking, Néel or Curie temperature transitions by heat treatment in presence/absence of a magnetic field · CPC title

• C21D9/0006 Primary

  Details, accessories not peculiar to any of the following furnaces (control devices C21D11/00) · CPC title

• C21D1/26

  Methods of annealing · CPC title