DETAILED ACTION
Notice of Pre-AIA or AIA Status
1. The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
Election/Restrictions
2. Applicant’s election without traverse of Group I (claims 1-21) in the reply filed on 03/13/2026 is acknowledged.
3. Claims 22-25 are withdrawn from further consideration pursuant to 37 CFR 1.142(b) as being drawn to a nonelected invention, there being no allowable generic or linking claim. Election was made without traverse in the reply filed on 03/13/2026.
Claim Rejections - 35 USC § 103
4. In the event the determination of the status of the application as subject to AIA 35 U.S.C. 102 and 103 (or as subject to pre-AIA 35 U.S.C. 102 and 103) is incorrect, any correction of the statutory basis (i.e., changing from AIA to pre-AIA ) for the rejection will not be considered a new ground of rejection if the prior art relied upon, and the rationale supporting the rejection, would be the same under either status.
5. The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action:
A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made.
6. Claims 1-11, 13-21 are rejected under 35 U.S.C. 103 as being unpatentable over Ashraf et al. (US 2021/0175082 A1) in view of Shen (US 2021/0098400 A1).
Note:
As to claim 1, Ashraf discloses a method of plasma etching a silicon carbide substrate to form a tapered feature, the method comprising the steps of:
providing a substrate with a hard mask (32) formed thereon on a substrate support in a chamber, the hard mask having an opening, wherein the substrate is formed from silicon carbide (paragraph 0055, Fig 3); and
performing a plasma etch step to anisotropically etch the substrate through the opening to produce a tapered feature (Fig 3, paragraph 0059-0065, Table 1);
wherein the plasma etch step comprises generating a plasma from an etchant gas mixture comprising at least one chlorine-containing component, at least one inert gas component (i.e. Ar) and at least one passivation material precursor (i.e. SiCl4) (See paragraph 0058, Table 1, and wherein the anisotropic etching of the substrate comprises deposition of a passivation material (40) on at least the opening such that the tapered feature comprises at least two sidewalls and each sidewall is inclined at an angle between 85 ° to 90 °
As to claim 1, Ashraf fails to disclose each sidewall is inclined at an angle of less than 85 ° to the horizontal. However, Ashraf clearly discloses an etching process result to each sidewall is inclined at an angle of 85-90 ° or 86-90 ° to the horizontal (paragraph 0027).
Shen discloses an etching process result sidewall is inclined at an acute angle of less than 90°, including angle of about 70° (See abstract, paragraph 0027, Note: 70 ° is within applicant’s range of “less than 85 °). It would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, to modify Ashraf in view of Shen by having each sidewall is inclined at an angle of less than 85 ° because in the case where the claimed ranges "overlap or lie inside ranges disclosed by the prior art" a prima facie case of obviousness exists (See MPEP 2144.05(I)).
As to claim 2, Ashraf discloses the at least one passivation material precursor comprises at least one silicon-containing component (i.e. SiCl4; See paragraph 0021, 0058, Table 1).
As to claim 3, Ashraf discloses wherein the at least one silicon-containing component comprises SiCl4 (See paragraph 0021, 0058, Table 1).
As to claim 4, Ashraf discloses wherein a total flow rate of the at least one silicon-containing component (i.e. SiCl4) at the beginning of the plasma etch step is from about 19 sccm (Table 1, within applicant’s range of “about 10 sccm to about 50 sccm”).
As to claim 5, Ashraf discloses wherein the at least one passivation material precursor comprises at least one oxygen-containing component (See paragraph 0021, 0058, Table 1).
As to claim 6, Ashraf discloses wherein the at least one oxygen-containing component comprises O2 gas (See paragraph 0021, 0058, Table 1).
As to claim 7, Ashraf discloses wherein a total flow rate of the at least one oxygen-containing component (O2) at the beginning of the plasma etch step is about 17 sccm to 25 sccm (See Table 1, within applicant’s range of “about 12 sccm to about 75 sccm”).
As to claim 8, Ashraf discloses wherein the plasma etch step comprises increasing a flow rate of the at least one passivation material precursor (e.g. O2) during the plasma etch step (See Table 1).
As to claim 9, Ashraf discloses wherein the flow rate of the at least one passivation material precursor (O2) in sccm at the end of the plasma etch step is at least two times higher than the flow rate of the at least one passivation material precursor in sccm at the beginning of the plasma etch step (See paragraph 0016; Fig 5; Table 1; beginning flow rate 25 sccm; ending flow rate 98 sccm or 100 sccm).
As to claim 10, Ashraf discloses wherein the at least one chlorine-containing component comprises Cl2 gas (paragraph 0021, 0058, Table 1).
As to claim 11, Ashraf discloses wherein the at least one inert gas component comprises argon (Ar gas; See paragraph 0021, 0022, 0058).
As to claim 13, Ashraf fails to disclose wherein each sidewall is inclined at an angle of 81 ° to the horizontal or less. However, Ashraf clearly discloses each sidewall is inclined at an angle of less than 90° , including example of 85° to the horizontal (See Fig 3-4; paragraph 0028). Shen discloses an etching process result sidewall is inclined at an acute angle of less than 90 °, including angle of about 70 ° (See abstract, paragraph 0027, Note: 70 ° is within applicant’s limitation “at an angle of 81° to the horizontal or less”). It would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, to modify Ashraf in view of Shen by having each sidewall is inclined at an angle of less than 85 ° because in the case where the claimed ranges "overlap or lie inside ranges disclosed by the prior art" a prima facie case of obviousness exists (See MPEP 2144.05(I)).
As to claim 14, Ashraf discloses a total flow rate of at least one chlorine-containing component in sccm at the end of the etch step is 160 sccm and a total flow rate of the at least one passivation material precursor (O2) at the end of the plasma in sccm is 98 sccm (See Table 1). Any person having ordinary skill in the art would be able to calculate a ratio of a total flow rate of the at least one chlorine-containing component in sccm at the end of the plasma etch step to a total flow rate of the at least one passivation material precursor in sccm at the end of the plasma etch step as shown below:
Flow Ratio of at least one chlorine-containing component to the at least one passivation material precursor = 160 sccm : 98 sccm = 1.63: 1 (within applicant’s range of “about 1:1 to about 3:1”).
As to claim 15, Ashraf discloses a total flow rate of the at least one chlorine-containing component is at least 100 sccm (Table 1).
As to claim 16, Ashraf discloses the plasma etch step is performed using a plasma source that supplies a power of from about 800 W to about 2000 W including example of 950 W or 1500 W to the plasma (See paragraph 0058, Table 1, within applicant’s range of “from about 800 W to about 2400 W” ).
As to claim 17, Ashraf discloses wherein an initial bias power of from 100 W to 1600 W or 400 W to 1400 W is applied to the substrate support during the plasma etch step (paragraph 0019, within applicant’s range of “from 100 W to 1500 W”).
As to claim 18, Ashraf discloses the plasma etch step comprises decreasing a bias power applied to the substrate support during the plasma etch step (See paragraph 0019 “the bias power applied to the substrate during the second plasma etch step can be lower than the bias applied to the substrate during the first plasma etch”).
As to claim 19, Ashraf discloses wherein an initial bias power applied to the substrate support is decreased by at least 50% during the plasma etch step (See paragraph 0019; bias power during the first plasma is between 400 W to 1400 W; bias power during the second bias is 140-220 W or 170 to 210 W).
As to claim 20, Ashraf discloses the substrate support (platen) is maintained at a temperature of 20 °C (Table 1; within applicant’s range of “between about 5 °C and about 50 °C).
As to claim 21, Ashraf discloses wherein a pressure within the chamber during the plasma etch step is from between 2 mtorr to 20 mtorr including example of 5 mtorr or 8 mtorr (See paragraph 0058, Table 1; within applicant’s range of from 2 mtorr to 60 mtorr).
7. Claim 12 is rejected under 35 U.S.C. 103 as being unpatentable over Ashraf et al. (US 2021/0175082 A1) in view of Shen (US 2021/0098400 A1) as applied to claims 1-11 above, and further in view of Chiu (US 2016/0111324 A1).
As to claim 12, Ashraf and Shen fail to disclose a total flow rate of the at least one inert gas component is from about 500 sccm to about 800 sccm. However, Ashraf clearly discloses to use argon during an etching process (See paragraph 0021, 0022, 0058). Chiu discloses to use argon at a flow rate between 600 sccm to 1200 sccm (paragraph 0036, within applicant’s range “from about 500 sccm to about 800 sccm”). It would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, to modify Ashraf in view of Shen by using argon at a flow rate of 600 sccm to 800 sccm because in the case where the claimed ranges "overlap or lie inside ranges disclosed by the prior art" a prima facie case of obviousness exists (See MPEP 2144.05(I)).
Conclusion
8. Any inquiry concerning this communication or earlier communications from the examiner should be directed to BINH X TRAN whose telephone number is (571)272-1469. The examiner can normally be reached Monday-Friday.
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BINH X. TRAN
Examiner
Art Unit 1713
/BINH X TRAN/ Primary Examiner, Art Unit 1713
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