High purity carbon/carbon composite useful as a crucible susceptor

• US 5,858,486 A
• Filed: 06/03/1997
• Issued: 01/12/1999
• Est. Priority Date: 02/27/1995
• Status: Expired due to Fees

• Current Assignee: HITCO Carbon Composites, Inc. (Sgl Carbon Se)
• Original Assignee: SGL Carbon Composites, Inc.
• Inventors: Hathcock, Joseph David, Winsek, Peter M., Metter, Robert Howard
• Primary Examiner(s): RAIMUND, CHRISTOPHER W
• Application Number:
  US08/868,211
• Time in Patent Office: 588 Days
• Field of Search: 442/179, 428/408, 428/34.1, 117/13, 117/200
• US Class Current: 428/34.1
• CPC Class Codes: C04B 35/83 Carbon fibres in a carbon matrix
• CPC Class Codes: C30B 15/00 Single-crystal growth by pulling from a melt, e.g. Czochralski method under a protective fluid C30B27/00
• CPC Class Codes: C30B 15/10 Crucibles or containers for supporting the melt
• CPC Class Codes: C30B 15/14 Heating of the melt or the crystallised materials
• CPC Class Codes: C30B 35/00 Apparatus not otherwise provided for, specially adapted for the growth, production or after-treatment of single crystals or of a homogeneous polycrystalline material with defined structure
• CPC Class Codes: C30B 35/002 Crucibles or containers
• CPC Class Codes: D01F 11/125 Carbon
• CPC Class Codes: Y10T 117/10 Apparatus
• CPC Class Codes: Y10T 428/13 Hollow or container type article [e.g., tube, vase, etc.]
• CPC Class Codes: Y10T 428/30 Self-sustaining carbon mass or layer with impregnant or other layer
• CPC Class Codes: Y10T 442/2984 Coated or impregnated carbon or carbonaceous fiber fabric

Abstract

A Czochralski process furnace component comprises a high purity, semiconductor standard composite including a carbon fiber reinforced carbon matrix having a total level of metal impurity below about 10 ppm, preferably below about 5 ppm, and most preferably having a level of metal impurity below the detection limit of inductively coupled plasma spectroscopy for the metals Ag, Al, Ba, Be, Ca, Cd, Co, Cr, Cu, K, Mg, Mn, Mo, Na, Ni, P, Pb, Sr and Zn. A crucible susceptor for a crystal growing process for pulling a crystal ingot from a crystal material melt in a crucible comprises a high purity composite comprising a two dimensional, continuously woven carbon fiber fabric reinforced carbon matrix; the high purity composite having a total level of metal impurity less than about 10 parts per million; the crucible susceptor being a one piece, ply lay-up structure of said high purity composite, having a side ring and a base, said side ring and said base having substantially the same thickness.

Claims

1. A crucible susceptor for a crystal growing process for pulling a crystal ingot from a crystal material melt in a crucible, comprising:

a high purity composite comprising a two dimensional, continuously woven carbon fiber fabric reinforced carbon matrix;

said high purity composite having a total level of metal impurity less than about 10 parts per million;

said crucible susceptor being a one piece, ply lay-up structure of said high purity composite, having a side ring and a base, said side ring and said base having substantially the same thickness.

2. The crucible susceptor of claim 1 wherein the base is adapted to directly engage a crystal growing furnace pedestal.

3. The crucible susceptor of claim 1 wherein the thickness of the base and the side ring is between about 0.12 inches and about 0.35 inches.

4. The crucible susceptor of claim 1 wherein the high purity composite provides substantially uniform heat transfer from outside said susceptor to the crucible holding the melt.

5. The crucible susceptor of claim 1 having a refractory coating selected from the group consisting of carbides, borides, and nitrides.

6. The crucible susceptor of claim 1 having a refractory coating selected from the group consisting of silicon carbide, silicon nitride, boron nitride, pyrolytic boron nitride and silicon boride.

7. The crucible susceptor of claim 1 wherein said metal impurity consists essentially of the metals Ag, Al, Ba, Be, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Mo, Na, Ni, P, Pb, Sr, V and Zn.

8. The crucible susceptor of claim 1 wherein said high purity composite has a total level of metal impurity less than about 5 parts per million.

9. The crucible susceptor of claim 1 wherein said high purity composite has a level of metal impurity below the detection limit of inductively coupled plasma spectroscopy for the metals Ag, Al, Ba, Be, Ca, Cd, Co, Cr, Cu, K, Mg, Mn, Mo, Na, Ni, P, Pb, Sr and Zn.

10. The crucible susceptor of claim 1 wherein the high purity composite has an ultimate tensile strength of about 25 to about 100 ksi and a tensile modulus of about 3 to about 30 msi.

11. The crucible susceptor of claim 1 wherein the high purity composite has a flexural strength of about 15 to about 60 ksi and a compressive strength of about 10 to about 50 ksi.

12. The crucible susceptor of claim 1 wherein the high purity composite has a fracture toughness as measured by Izod impact of about 5 to about 25 ft lb/in.

13. The crucible susceptor of claim 1 wherein the high purity composite has an in plane thermal expansion coefficient of zero to about 2×

10⁶ and a cross-ply thermal expansion coefficient of about 6 to about 10×

10⁶.

14. The crucible susceptor of claim 1 wherein the high purity composite has an in-plane thermal expansion coefficient of about 1.4×

10⁶.

15. The crucible susceptor of claim 1 wherein the high purity composite has an in-plane thermal conductivity of about 20 to about 500 W/mK and a cross-ply thermal conductivity of about 5 to about 200 W/mK.

16. The crucible susceptor of claim 1 wherein the high purity composite has a thermal conductivity of about 100 W/mK.

17. The crucible susceptor of claim 1 wherein the high purity composite has a thermal emissivity of about 0.4 to about 0.8.

18. The crucible susceptor of claim 1 wherein the high purity composite has a thermal emissivity of about 0.52.

19. The crucible susceptor of claim 1 having an electrical resistivity of about 1×

10^-4 to about 1×

10^-2 ohm-cm.

20. A single crystal growing process for pulling a single crystal ingot from a crystal material melt, including:

providing the crystal material melt in a crucible, and,

intimately supporting the crucible with the crucible susceptor of claim 1.

21. The process of claim 20 including setting the crucible susceptor directly upon a crystal growing furnace pedestal.

22. The process of claim 20 wherein the crystal material is selected from the group consisting of sapphire, silicon, gallium arsenide and cadmium zinc telluride.

23. A Czochralski crystal growing process for pulling a semiconductor ingot from a semiconductor material melt, including:

providing the semiconductor material melt in a quartz crucible, and,

intimately supporting the crucible with the crucible susceptor of claim 1.

24. The process of claim 23 including setting the crucible susceptor directly upon a Czochralski crystal growing furnace pedestal.

25. The process of claim 23, wherein the semiconductor ingot is a silicon ingot, including cutting the silicon ingot into silicon wafers, and further including providing said silicon wafers with an electrical breakdown time of greater than 300 microseconds.

26. The process of claim 23, wherein the semiconductor ingot is a silicon ingot, including cutting the silicon ingot into silicon wafers, and further including providing a yield greater than 68 percent of good-for-structure silicon semiconductor wafers.

27. The process of claim 23, wherein the semiconductor is selected from the group consisting of silicon, gallium arsenide and cadmium zinc telluride.