Nitrogen passivation of interface states in SiO2/SiC structures

• US 20040101625A1
• Filed: 08/14/2003
• Published: 05/27/2004
• Est. Priority Date: 08/30/2002
• Status: Active Grant

• Current Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Das, Mrinal Kanti, Saxler, Adam William
• Granted Patent: US 7,022,378 B2
• Time in Patent Office: Days
• US Class Current: 427/378
• CPC Class Codes: H01L 21/02167 the material being a silicon carbide not containing oxygen, e.g. SiC, SiC:H or silicon carbonitrides H01L21/02126 and H01L21/0214 take precedence
• CPC Class Codes: H01L 21/022 the layer being a laminate, i.e. composed of sublayers, e.g. stacks of alternating high-k metal oxides adhesion layers or buffer layers H01L21/02304, H01L21/02362
• CPC Class Codes: H01L 21/02332 into an oxide layer, e.g. changing SiO to SiON
• CPC Class Codes: H01L 21/02337 treatment by exposure to a gas or vapour
• CPC Class Codes: H01L 21/049 Conductor-insulator-semiconductor electrodes, e.g. MIS contacts
• CPC Class Codes: H01L 21/3143 composed of alternated layers or of mixtures of nitrides and oxides or of oxinitrides, e.g. formation of oxinitride by oxidation of nitride layers
• CPC Class Codes: H01L 21/3145 formed by deposition from a gas or vapour

Abstract

A nitrided oxide layer on a silicon carbide layer is processed by annealing the nitrided oxide layer in a substantially oxygen-free nitrogen containing ambient. The anneal may be carried out at a temperature of greater than about 900° C., for example, a temperature of about 1100° C., a temperature of about 1200° C. or a temperature of about 1300° C. Annealing the nitrided oxide layer may be carried out at a pressure of less than about 1 atmosphere, for example, at a pressure of from about 0.01 to about 1 atm or, in particular, at a pressure of about 0.2 atm. The nitrided oxide layer may be an oxide layer that is grown in a N₂O and/or NO containing ambient, that is annealed in a N₂O and/or NO containing ambient or that is grown and annealed in a N₂O and/or NO containing ambient.

Claims

1. A method of processing a nitrided oxide layer on a silicon carbide layer, the method comprising:

annealing the nitrided oxide layer in a substantially oxygen-free nitrogen containing ambient.

2. The method of claim 1, wherein annealing the nitrided oxide layer in a substantially oxygen-free nitrogen containing ambient is carried out at a temperature of greater than about 900°

C.

3. The method of claim 1, wherein annealing the nitrided oxide layer in a substantially oxygen-free nitrogen containing ambient is carried out at a temperature of greater than about 1000°

C.

4. The method of claim 1, wherein annealing the nitrided oxide layer in a substantially oxygen-free nitrogen containing ambient is carried out at a temperature of about 1100°

C.

5. The method of claim 1, wherein annealing the nitrided oxide layer in a substantially oxygen-free nitrogen containing ambient is carried out at a temperature of about 1200°

C.

6. The method of claim 1, wherein annealing the nitrided oxide layer in a substantially oxygen-free nitrogen containing ambient is carried out at a pressure of less than about 1 atmosphere.

7. The method of claim 1, wherein annealing the nitrided oxide layer in a substantially oxygen-free nitrogen containing ambient is carried out at a pressure of from about 0.01 to about 1 atm.

8. The method of claim 1, wherein annealing the nitrided oxide layer in a substantially oxygen-free nitrogen containing ambient is carried out at a pressure of about 0.2 atm.

9. The method of claim 1, further comprising growing an oxide layer in a N₂O and/or NO containing ambient so as to provide the nitrided oxide layer.

10. The method of claim 1, further comprising annealing an oxide layer in a N₂O and/or NO containing ambient so as to provide the nitrided oxide layer.

11. The method of claim 1, further comprising:

growing an oxide layer in a N₂O and/or NO containing ambient; and

annealing the grown oxide layer in a N₂O and/or NO containing ambient so as to provide the nitrided oxide layer.

12. The method of claim 1, wherein the substantially oxygen-free nitrogen containing ambient comprises a NH₃ containing ambient.

13. The method of claim 12, wherein the substantially oxygen-free nitrogen containing ambient comprises NH₃ and at least one inert gas.

14. The method of claim 12, wherein a flow rate of the NH₃ is from about 1 and about 10 Standard Liters per Minute (SLM).

15. The method of claim 12, wherein a flow rate of the NH₃ provides a gas velocity of from about 0.1 cm/sec to about 1000 cm/sec.

16. The method of claim 12, wherein a flow rate of the NH₃ provides a gas velocity of from about 1 cm/sec to about 100 cm/sec.

17. The method of claim 12, wherein the substantially oxygen-free nitrogen containing ambient comprises NH₃ and one or more of N₂, Ar, and/or He.

18. The method of claim 12, wherein the substantially oxygen-free nitrogen containing ambient comprises NH₃ and N₂ in a ratio of about 1:

3.

19. The method of claim 12, wherein the substantially oxygen-free nitrogen containing ambient comprises NH₃ and H₂.

20. The method of claim 12, wherein the substantially oxygen-free nitrogen containing ambient comprises NH₃ and SiH₄.

21. The method of claim 20, wherein the SiH₄ and NH₃ are provided in a reaction chamber containing the nitrided oxide layer such that the SiH₄ and NH₃ are not mixed until a region of the reaction chamber proximate the nitrided oxide layer.

22. The method of claim 1, wherein the nitrided oxide layer comprises a thermally grown oxide layer.

23. The method of claim 1, wherein the nitrided oxide layer comprises a deposited oxide layer.

24. The method of claim 1, wherein annealing the nitrided oxide layer in a substantially oxygen-free nitrogen containing ambient comprises annealing the nitrided oxide layer in a substantially oxygen-free nitrogen containing ambient at a temperature of greater than about 1000°

C. and at a pressure of less than 1 atmosphere.

25. The method of claim 24, wherein the substantially oxygen-free nitrogen containing ambient comprises NH₃.

26. The method of claim 1, wherein annealing the nitrided oxide layer in a substantially oxygen-free nitrogen containing ambient is carried out at a temperature of about 1300°

C.