Office Action 4: Notice of Allowance (2025-03-04)

CLAIMS:
AMENDMENTS TO THE CLAIMS

1\. (Currently Amended) A method for forming a wide band gap semiconductor device, the method comprising:forming a gate insulation layer on a wide band gap semiconductor substrate;
performing a first annealing process during which the gate insulation layer is annealed using at least a first reactive gas species, wherein the first annealing process is performed in a reactive gas atmosphere comprising at least 0.1 vol% of the first reactive gas species and at most 0.1 vol% of the second reactive gas species;
performing a second annealing process separate from the first annealing process and during which the gate insulation layer is annealed using at least a second reactive gas species, wherein the second annealing process is performed in a reactive gas atmosphere comprising at least 0.1 vol% of the second reactive gas species and at most 0.1 vol% of the first reactive gas species;
diluting the first reactive gas species with an inert gas so that a volume percent of the first reactive gas species is at least lvol% and at most 50vol%;and
annealing the gate insulation layer in an inert gas atmosphere,
wherein the first reactive gas species differs from the second reactive gas species,
 the first reactive gas species is nitric oxide.

2\. (Cancelled)

3\. (Cancelled)
4\. (Currently Amended) The method of claim 1, wherein the second reactive gas species is one of nitrous oxide, hydrogen, ammonia, hydrogen peroxide, nitric acid, water vapor, phosphoryl chloride, and oxygen.

5\. (Cancelled)

6\. (Previously Presented) The method of claim 1, further comprising:diluting the second reactive gas species with an inert gas so that a volume percent of the second reactive gas species is at least O.lvol% and at most lOvol%, and wherein the second reactive gas species is ammonia.

7\. (Cancelled)

8\. (Previously Presented) The method of claim 1, wherein the annealing of the gate insulation layer in the inert gas atmosphere comprises:

heating the gate insulation layer in the inert gas atmosphere at a temperature lower than 1200°C to reduce a hydrogen concentration within the gate insulation layer.

9\. (Currently Amended) The method of claim 8, wherein the second reactive gas species comprises ammonia, and wherein a volume percent of the second reactive gas species is at least .lvol%.

10\. (Currently Amended) The method of claim 8, wherein the first reactive gas species comprises at least Svol% nitric oxide, wherein the inert gas atmosphere comprises at least 90% nitrogen, and wherein a duration of the annealing in the inert gas atmosphere is shorter than a duration of the annealing in the first reactive gas species and/or the second reactive gas species.

11\. (Original) The method of claim 8, wherein the inert gas atmosphere has a concentration of oxygen of at most O.Svol%.

12\. (Original) The method of claim 8, wherein a duration of each annealing of the gate insulation layer is at least 10 minutes and at most 600 minutes.

13\. (Original) The method of claim 8, wherein an annealing temperature of each annealing of the gate insulation layer is at least 600°C and at most 1200°C.

14\. (Previously Presented) The method of claim 1, further comprising:
 the gate insulation layer is annealed, heating the gate insulation layer in an inert gas atmosphere at a temperature of at least 950°C.

15\. (Previously Presented) The method of claim 1, further comprising:after the gate insulation layer is annealed, forming a gate electrode on the gate insulation layer.

16\. (Original) The method of claim 15, wherein the gate electrode is a gate trench electrode that extends from a surface of the wide band gap semiconductor substrate into the wide band gap semiconductor substrate.

17\. (Original) The method of claim 1, wherein the wide band gap semiconductor substrate is a silicon carbide substrate.

18\. (Original) The method of claim 1, wherein the gate insulation layer is a silicon dioxide layer.

19\. (Cancelled)

20-27. (Cancelled)2126

28\. (New) A method for forming a wide band gap semiconductor device, the method comprising:

forming a gate insulation layer on a wide band gap semiconductor substrate;
performing a first annealing process during which the gate insulation layer is annealed using at least a first reactive gas species, wherein the first annealing process is performed in a reactive gas atmosphere comprising at least 0.1 vol% of the first reactive gas species and at most 0.1 vol% of the second reactive gas species;
performing a second annealing process separate from the first annealing process and during which the gate insulation layer is annealed using at least a second reactive gas species, wherein the second annealing process is performed in a reactive gas atmosphere comprising at least 0.1 vol% of the second reactive gas species and at most 0.1 vol% of the first reactive gas species;
diluting the second reactive gas species with an inert gas so that a volume percent of the second reactive gas species is at least 0.lvol% and at most lOvol%; and
annealing the gate insulation layer in an inert gas atmosphere,
wherein the first reactive gas species differs from the second reactive gas species,
wherein the second reactive gas species is ammonia.

29\. (New) The method of claim 28, further comprising:after the gate insulation layer is annealed, forming a gate electrode on the gate insulation layer.

30\. (New) The method of claim 29, wherein the gate electrode is a gate trench electrode that extends from a surface of the wide band gap semiconductor substrate into the wide band gap semiconductor substrate.

31\. (New) The method of claim 28, wherein the annealing of the gate insulation layer in the inert gas atmosphere comprises:heating the gate insulation layer in the inert gas atmosphere at a temperature lower than 1200°C to reduce a hydrogen concentration within the gate insulation layer.

32\. (New) The method of claim 31, wherein the first reactive gas species comprises nitric oxide, and wherein a volume percent of the first reactive gas species is at least 0.lvol%.

33\. (New) The method of claim 31, wherein the first reactive gas species comprises at least Svol% nitric oxide, wherein the inert gas atmosphere comprises at least 90% nitrogen, and wherein a duration of the annealing in the inert gas atmosphere is shorter than a duration of the annealing in the first reactive gas species and/or the second reactive gas species.

34\. (New) The method of claim 31, wherein the inert gas atmosphere has a concentration of oxygen of at most O.Svol%.

35\. (New) The method of claim 31, wherein a duration of each annealing of the gate insulation layer is at least 10 minutes and at most 600 minutes.

36\. (New) The method of claim 31, wherein an annealing temperature of each annealing of the gate insulation layer is at least 600°C and at most 1200°C.

OFFICE ACTION:
Reasons for Allowance
The following is an examiner’s statement of reasons for allowance: Claims 1 and 28 recite the limitations  diluting the first reactive gas species with an inert gas so that a volume percent of the first reactive gas species is at least 1 vol% and at most 50 vol%, and wherein the first reactive gas species is nitric oxide and diluting the second reactive gas species with an inert gas so that a volume percent of the second reactive gas species is at least 0.1 vol% and at most 10 vol%, and wherein the second reactive gas species is ammonia, respectively. The closest prior art references US 20040101625 and US 20020102358  neither alone nor in combination disclose or suggest these limitations in combination with the other limitations as set forth in the claims, respectively. Claims 4, 6, 8-18, and 29-36 depend from these claims respectively.
Any comments considered necessary by applicant must be submitted no later than the payment of the issue fee and, to avoid processing delays, should preferably accompany the issue fee.  Such submissions should be clearly labeled “Comments on Statement of Reasons for Allowance.”
Conclusion

APPLICANT REBUTTAL: REMARKS
Claims 1, 4-6, 8-18, and 20-27 were pending at the time of the Office Action dated December 3, 2024. Claims 1, 4, 8-18, and 20-27 are rejected. Claims 5-6 are objected to as being dependent upon a rejected base claim, but would be allowable if rewritten in independent form including all of the limitations of the base claim and any intervening claims. Applicant respectfully submits that the present application is in condition for allowance at least for the reasons explained below.
Claim Amendments
Independent claim 1 has been amended to include the features of
allowable
dependent claim 5 (see Sections 8-9 of the Office Action for indication of allowable subject matter).
Claims 5 and 20-27 have been cancelled.
Claims 4, 9 and 10 have been amended, in view of the changes to claim 1.
New independent claim 28 includes the features of prior independent claim 1 and
allowable
dependent claim 6 (see Sections 8-9 of the Office Action for indication of allowable subject matter).
New dependent claims 29-36 correspond to dependent claims 15-16 and 8-13, respectively.
No new matter is added by way of the claim amendments made herein, and entry is respectfully requested.
Patentability of Pending Claims
All claims pending herein recite subject matter deemed by the Office to be allowable. Hence, withdrawal of all claim rejections is respectfully requested.
Conclusion


CITED REFERENCE SUMMARIES: Ref US20040101625: 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.
Ref US20020102358: Claims:
1. A method of forming an insulator in a silicon carbide electronic device, comprising: 
fabricating a nitrided oxide layer on a layer of silicon carbide; and  annealing the nitrided oxide layer in an environment containing hydrogen.
2. The method according to claim 1, wherein the silicon carbide layer comprises 4H polytype silicon carbide.
3. The method according to claim 1, wherein the silicon carbide layer comprises a silicon carbide layer on a non-silicon carbide substrate.
4. The method according to claim 1, wherein the silicon carbide layer comprises a portion of a silicon carbide substrate.
5. The method of claim 1, wherein the step of fabricating a nitrided oxide layer comprises at least one of forming the oxide layer in at least one of nitric oxide and nitrous oxide and annealing an existing oxide layer in at least one of nitric oxide and nitrous oxide.
6. The method of claim 1, wherein the step of fabricating a nitrided oxide layer comprises the steps of: 
fabricating an oxide layer; and  fabricating a nitride layer on the oxide layer so as to nitridate the oxide layer on which the nitride layer is fabricated.
7. The method of claim 6, wherein the step of annealing the oxide layer in an environment containing hydrogen is provided substantially concurrently with the step of fabricating the nitride layer so that the step of fabricating a nitride layer on the oxide layer comprises fabricating a nitride layer on the oxide layer so as to nitridate and hydrogenate the oxide layer on which the nitride layer is fabricated.
8. The method of claim 1, wherein the step of annealing the oxide layer comprises heating the oxide layer to a temperature of greater than about 400° C. in a hydrogen containing environment as part of another processing step.
9. The method of claim 1, wherein the step of annealing the oxide layer comprises annealing the oxide layer at a temperature of greater than about 400° C. in a hydrogen containing environment.
10. The method of claim 1, wherein the step of annealing the oxide layer comprises annealing the oxide layer at a temperature of less than about 900° C. in a hydrogen containing environment.
11. The method of claim 1, wherein the step of annealing the oxide layer comprises annealing the oxide layer at a temperature of between about 400° C. and about 1000° C. in a hydrogen containing environment.
12. The method of claim 1, wherein the step of annealing the oxide layer comprises annealing the oxide layer at a temperature of between about 400° C. and about 800° C. in a hydrogen containing environment.
13. The method of claim 1, further comprising the step of performing subsequent high temperature processing steps in a hydrogen containing environment.
14. The method of claim 1, wherein the step of annealing is preceded by the step of forming metallization for a semiconductor device associated with the oxide layer.
15. The method of claim 14, wherein the step of annealing the oxide layer comprises annealing the oxide layer at a temperature of less than about 900° C. in a hydrogen containing environment.
16. The method of claim 15, wherein the step of annealing the oxide layer comprises a contact anneal.
17. The method of claim 1, wherein the step of annealing comprises annealing the oxide layer in forming gas having about 4% hydrogen and 96% inert gases.
18. The method of claim 1 further comprising forming a silicon carbide metal oxide semiconductor device having the oxide layer as a gate oxide of the metal oxide semiconductor device.
19. The method of claim 1, wherein the step of annealing the oxide layer is carried out for at least about 2 minutes.
20. A method of fabricating an oxide layer on a silicon carbide layer, comprising: 
nitriding the oxide layer on the silicon carbide layer with at least one of nitric oxide and nitrous oxide; and  annealing the nitrided oxide layer at a temperature of between about 400° C about 900° C. in a hydrogen containing environment for at least about 2 minutes.