Method of growing high quality, thick SiC epitaxial films by eliminating silicon gas phase nucleation and suppressing parasitic deposition

Patent metadata

Field	Value
Publication number	US-9885124-B2
Application number	US-201214360064-A
Country	US
Kind code	B2
Filing date	Nov 20, 2012
Priority date	Nov 23, 2011
Publication date	Feb 6, 2018
Grant date	Feb 6, 2018

Abstract

Methods for forming an epilayer on a surface of a substrate are generally provided. For example, a substrate can be positioned within a hot wall CVD chamber (e.g., onto a susceptor within the CVD chamber). At least two source gases can then be introduced into the hot wall CVD chamber such that, upon decomposition, fluorine atoms, carbon atoms, and silicon atoms are present within the CVD chamber. The epilayer comprising SiC can then be grown on the surface of the substrate in the presence of the fluorine atoms.

First claim

The invention claimed is:

1. A method of forming an epilayer on a surface of a substrate, the method comprising:
positioning the substrate within a hot wall CVD chamber, wherein the substrate is a silicon carbide seed substrate;
introducing SiF 4 as a fluorinated Si-source gas and introducing a carbon source gas into the hot wall CVD chamber; and
growing a homeoepitaxial film on the silicon carbide seed substrate upon chemical reaction of the SiF 4 with the carbon source gas, the homeoepitaxial film comprising a 4H or 6H SiC crystal, the homeoepitaxial film growing on the silicon carbide seed substrate at a growth temperature within the hot wall CVD chamber of about 1400° C. to about 2000° C., the homeoepitaxial film comprising silicon and carbon in the 4H or 6H crystal at a 1:1 stoichiometric ratio.

2. The method as in claim 1 , wherein the growth temperature is about 1500° C. to about 1800° C.

3. The method as in claim 1 , wherein parasitic deposition is substantially prevented on the reactor parts to increase the reusability of the reactor parts and enable longer duration growth.

4. The method as in claim 1 , further comprising:
prior to growing the homeoepitaxial film, growing a buffer epilayer on the surface of the silicon carbide seed substrate, wherein the buffer epilayer comprises SiC.

5. The method as in claim 1 , further comprising:
prior to growing the homeoepitaxial film, applying a molten mixture onto the surface of the silicon carbide seed substrate to form a treated surface thereon, wherein the molten mixture comprises KOH and a buffering agent.

6. The method as in claim 5 , wherein the buffering agent comprises MgO, GaO, or a mixture thereof.

7. The method as in claim 1 , further comprising:
prior to growing the homeoepitaxial film, applying a molten mixture onto the surface of the silicon carbide seed substrate to form a treated surface thereon, wherein the molten mixture comprises KOH—NaOH eutectic and a buffering agent.

8. The method as in claim 1 , wherein during the growth of the homeoepitaxial film, the CVD chamber has an atmosphere that includes Si—Si vapor in an amount that is less than 5% by volume.

9. The method as in claim 8 , wherein during the growth of the homeoepitaxial film, the atmosphere of the CVD chamber includes Si—Si vapor in an amount that is less than 1% by volume.

10. The method as in claim 8 , wherein during the growth of the homeoepitaxial film, the atmosphere of the CVD chamber is substantially free from Si—Si vapor.

11. The method as in claim 1 , wherein the fluorinated Si-source gas is the only silicon source introduced into the hot wall CVD chamber.

12. The method as in claim 1 , wherein the fluorinated Si-source gas is the only fluorine source introduced into the hot wall CVD chamber.

13. The method as in claim 1 , wherein the carbon source gas comprises propane.

14. The method as in claim 1 , wherein the carbon source gas comprises methane.

15. The method as in claim 1 , wherein the carbon source gas comprises ethylene.

16. The method as in claim 1 , wherein the volumetric ratio of the fluorinated Si-source gas to the carbon source gas is sufficient to provide a C:Si ratio of about 0.3 to about 1.6.

17. The method as in claim 16 , wherein the substrate is a 4H SiC substrate.

18. The method as in claim 1 , wherein the homeoepitaxial film is grown to a thickness that is about 1 μm to about 100 μm.

19. The method as in claim 1 , wherein the homeoepitaxial film is grown to a thickness that is greater than 100 μm.

20. The method as in claim 1 , wherein the homeoepitaxial film has a smooth surface having a roughness RMS of about 0.5 nm or less.

21. The method as in claim 1 , wherein the homeoepitaxial film is grown at a growth rate of about 1 μm/hour to about 30 μm/hour.

22. The method as in claim 1 , wherein the homeoepitaxial film is grown at a growth rate of 30 μm/hour or faster.

23. The method as in claim 1 , wherein the silicon carbide seed substrate is cut off-axis at an angle of 4° or 8°.

Assignees

• Univ South Carolina

Inventors

• Sudarshan Tangali S
• Song Haizheng
• Rana Tawhid

Classifications

• H10P90/126

  by chemical etching · CPC title

• H10P70/50

  characterised by the part to be cleaned · CPC title

• H10P50/644

  Anisotropic liquid etching (H10P50/61 takes precedence) · CPC title

• H10P14/3408

  Silicon carbide · CPC title

• H10P14/3258

  Crystal orientation · CPC title