Phase controlled sublimation

• US 20040216661A1
• Filed: 04/30/2003
• Published: 11/04/2004
• Est. Priority Date: 04/30/2003
• Status: Active Grant

• Current Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Kordina, Olof Claes Erik
• Granted Patent: US 7,147,713 B2
• Time in Patent Office: Days
• US Class Current: 117/92
• CPC Class Codes: C30B 25/14 Feed and outlet means for the gases; Modifying the flow of the reactive gases
• CPC Class Codes: C30B 29/36 Carbides
• CPC Class Codes: Y10T 117/10 Apparatus

Abstract

A method of forming a silicon carbon compound. A silicon source is introduced into an environment. Silicon particles are formed therefrom. One or more hydrocarbons are introduced into the environment separately from the silicon source, thereby forming one or more silicon carbon compounds. A dissociation enhancer may be introduced into the environment to minimize silicon particle size prior to it joining the hydrocarbon source.

Claims

1. A method of forming a silicon carbon compound on a growing surface comprising:

introducing a silicon source into an environment;

forming silicon particles; and

introducing one or more hydrocarbons into the environment separately from the silicon source to form silicon-carbon particles;

wherein the one or more hydrocarbons are introduced at a distance from the growing surface sufficient to allow the formed silicon-carbon particles to sublime before reaching the growing surface, thereby forming one or more silicon carbon compounds on the growing surface.

2. The method of claim 1 further comprising:

introducing hydrogen chloride into the environment.

3. The method of claim 2 wherein the HCl is introduced into the environment separately from the silicon source and the hydrocarbon source.

4. The method of claim 3 wherein the silicon particles formed meet with the hydrogen chloride before meeting with the hydrocarbon flow.

5. The method of claim 1 wherein the silicon source is selected from the group consisting of silane, trichlorosilane, silicon tetrachloride, Si₂Cl₆, Si₃Cl₈ and a combination of two or more of the aforementioned compounds.

6. The method of claim 5 wherein the silicon source is silane.

7. The method of claim 1 wherein the silicon source is a chlorosilane and the method further comprises:

introducing hydrogen into the environment.

8. The method of claim 1 wherein the one or more hydrocarbons are in a carrier stream containing hydrogen.

9. The method of claim 1 wherein the concentration of silicon is greater than the concentration of the one or more hydrocarbons.

10. The method of claim 1 wherein the one or more hydrocarbons contains ethylene.

11. The method of claim 1 wherein the silicon source is transported in a carrier gas.

12. The method of claim 11 wherein the carrier gas is an inert gas.

13. The method of claim 12 wherein the inert gas is helium.

14. The method of claim 1 wherein the silicon source and the one or more hydrocarbons are kept substantially separate until they reach the sublimation zone.

15. The method of claim 1 wherein a second amount of one or more hydrocarbons is introduced into the environment with the silicon source in addition to the one or more hydrocarbons being introduced into the environment separately from the silicon source.

16. The method of claim 15 wherein the flow of the second amount of hydrocarbons is less than 5 sccm.

17. The method of claim 1 performed at a temperature below about 2400°

C.

18. The method of claim 17 performed at a temperature of below about 2100°

C.

19. The method of claim 1 wherein the flow rate of silicon source is in a range of about 300 standard cubic centimeter/minute-1 liter/minute.

20. The method of claim 1 wherein the flow rate of hydrocarbon is in the range of about 50 sccm-500 sccm.

21. The method of claim 1 wherein the flow rate of hydrogen chloride is in the range of about:

100 sccm-300 sccm.

22. The method of claim 1 wherein the flow rate of helium is in the range of about 1 liter/min-3 liters/min.

23. The method of claim 1 wherein the silicon source and the hydrocarbon source are physically separated within a growth chamber until they reach an area of predetermined temperature.

24. The method according to claim 2 wherein the silicon and hydrogen chloride are physically separated from the hydrocarbon flow within a growth chamber until they reach an area of predetermined temperature.

25. The method according to claim 2 wherein the silicon and hydrogen chloride are physically separated from the hydrocarbon flow within a growth chamber until the particle size is decreased to a predetermined size.

26. The method of claim 1 wherein the hydrocarbons are introduced into the environment at a distance of about 30 mm to 200 mm from the growing surface.

27. The method of claim 1 wherein the hydrocarbons are introduced into the environment at a distance of about 70 mm to 120 mm from the growing surface.

28. A silicon carbide crystal grown according to the method of claim 1.

29. A semiconductor device comprising a silicon carbide crystal formed according to the method of claim 1.

30. A method of forming a silicon carbon compound comprising:

introducing a silicon source and one or more hydrocarbons into an environment; and

subsequently introducing a dissociation enhancer into the environment.

31. The method of claim 30 wherein the dissociation enhancer is HCl.

32. The method of claim 30 wherein the silicon source is selected from the group consisting of silane, trichlorosilane, silicon tetrachloride, Si₂Cl₆, Si₃Cl₈ and a combination of two or more of the aforementioned compounds.

33. The method of claim 32 where the silicon source is silane.

34. A silicon carbide crystal formed according to claim 30.

35. A semiconductor device comprising a silicon carbide crystal formed according to the method of claim 30.

36. A sublimation chamber comprising:

a sample holder to hold a substrate;

one or more first inlets into the chamber;

one or more second inlets into the chamber;

wherein the first and second inlets are positioned such that material flows entering the chamber through the inlets join one another at a distance from the substrate sufficient to allow particles formed from the material flows to sublime before reaching the substrate.

37. The sublimation chamber of claim 36 further comprising:

one or more third inlets positioned so that a dissociation enhancer flow entering through the third outlets will aid in dissolving particles prematurely formed by material flows from the first and second inlets.

38. The sublimation chamber of claim 37 wherein the third inlets are positioned so that the third inlet flow interacts with the second inlet flow prior to the second inlet flow interacting with the first inlet flow.

39. The sublimation chamber of claim 36 further comprising:

one or more walls positioned between the first and second inlets to further separate material flows through the first and second inlets.

40. The sublimation chamber of claim 37 further comprising:

one or more walls positioned between the first and second inlets to further separate material flows through the first and second inlets;

and wherein the third inlets are on the same side of the wall as the second inlets.

41. A semiconductor device formed at least in part in the sublimation chamber of claim 36.

42. A silicon carbide crystal formed at least in part in the sublimation chamber of claim 36.