DETAILED ACTION
Notice of Pre-AIA or AIA Status
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
Double Patenting
The nonstatutory double patenting rejection is based on a judicially createddoctrine grounded in public policy (a policy reflected in the statute) so as to prevent the unjustified or improper timewise extension of the "right to exclude" granted by a patent and to prevent possible harassment by multiple assignees. A nonstatutory obviousness-type double patenting rejection is appropriate where the conflicting claims are not identical, but at least one examined application claim is not patentably distinct from the reference claim(s) because the examined application claim is either anticipated by, or would have been obvious over, the reference claim(s). See, e.g., In re Berg, 140 F.3d 1428, 46 USPQ2d 1226 (Fed. Cir. 1998); In re Goodman, 11 F.3d 1046, 29 USPQ2d 2010 (Fed. Cir. 1993); In re Longi, 759 F.2d 887, 225 USPQ 645 (Fed. Cir. 1985); In re Van Omum, 686 F.2d 937, 214 USPQ 761 (CCPA 1982); In re Vogel, 422 F.2d 438, 164 USPQ 619 (CCPA 1970); and In re Thorington, 418 F.2d 528, 163 USPQ 644 (CCPA 1969).
A timely filed terminal disclaimer in compliance with 37 CFR 1.321 (c) or 1.321(d)may be used to overcome an actual or provisional rejection based on a nonstatutory double patenting ground provided the conflicting application or patent either is shown to be commonly owned with this application, or claims an invention made as a result of activities undertaken within the scope of a joint research agreement.
Effective January 1, 1994, a registered attorney or agent of record may sign aterminal disclaimer. A terminal disclaimer signed by the assignee must fully comply with 37 CFR 3.73(b).
Claim 1 is rejected on the ground of nonstatutory obviousness-type double patenting as being unpatentable over claims 1, 7, 10-14, 20 of US Patent 12,494,372 in view of
Ikemoto et al. (JP 2015162630 A) in view of JP4653603 B2 (herein after ‘3603). Although the conflicting claims are not identical, they are not patentably distinct from each other.
Claim 1 of ‘4372: A method of plasma etching a compound semiconductor substrate to form a feature, the method comprising the steps of:
providing a substrate with a mask formed thereon, the mask having a mask opening, wherein the substrate is formed from a compound semiconductor material, and wherein the mask includes silicon dioxide;
performing a first plasma etch step to anisotropically etch the substrate through the mask opening to produce a majority of a partially formed feature having an opening and a bottom surface comprising a peripheral region;
performing a second plasma etch step to remove a region of the mask adjacent to the opening of the partially formed feature and thereby cause rounding of the edges of the substrate at the opening of the partially formed feature; and
performing a third plasma etch step to anisotropically etch the bottom surface of the partially formed feature through the mask opening of the mask while depositing a passivation material onto the mask and the opening of the partially formed feature so as to reduce a dimension of the opening of the partially formed feature, wherein the reduction of the dimension of the opening of the partially formed feature causes an attenuation in etching of the peripheral region and the opening of the partially formed feature thereby producing a fully formed feature having an opening with rounded edges, a bottom surface comprising a central region and an edge region, wherein the central region is deeper than the edge region of the bottom surface of the fully formed feature.
Regarding claim 1: Claim 1 of ‘4372 teaches about a method of plasma etching a compound semiconductor substrate to form a feature, the method comprising the steps of:
(a) providing the substrate with a mask formed thereon, the mask having an opening, wherein the substrate is formed from a compound semiconductor material;
(b) performing a first plasma etch step (first plasma etch step) to anisotropically etch the substrate through the opening to produce a partial form of the feature having a bottom surface comprising a peripheral region; and
(c) performing a second plasma etch step (third plasma etch of ‘4372) to anisotropically etch the bottom surface of the partial form of the feature through the opening while depositing a passivation material onto the mask so as to reduce a dimension of the opening, wherein the second plasma etch step comprises ramping a parameter between a beginning and an end of the second plasma etch step, wherein the reduction of the dimension of the opening causes an attenuation in etching of the peripheral region thereby producing a full form of the feature such that the bottom surface includes a central region and an edge region, wherein the central region is deeper than the edge region of the bottom surface of the full form of the feature, and wherein the parameter includes one or more of a gas mixture composition, a gas ratio, a flow rate, a processing time, an etch time, a plasma source power, a platen power, a bias power applied to the substrate, or a frequency of power applied.
Claim 1 does not explicitly talk about wherein the second plasma etch step comprises ramping a parameter between a beginning and an end of the second plasma etch step and wherein the parameter includes one or more of a gas mixture composition, a gas ratio, a flow rate, a processing time, an etch time, a plasma source power, a platen power, a bias power applied to the substrate, or a frequency of power applied.
However Ikemoto and ‘3630 teaches in an analogous art of a method of plasma etching a compound semiconductor substrate to form a feature, wherein the second plasma etch step comprises ramping a parameter between a beginning and an end of the second plasma etch step and wherein the parameter includes one or more of a gas mixture composition, a gas ratio, a flow rate, a processing time, an etch time, a plasma source power, a platen power, a bias power applied to the substrate, or a frequency of power applied (For clarification, ‘3630 teaches in page 9 during a second plasma etch process, the growth rate of the protective film 401 increases as the O2 flow ratio increases, the processing pressure increases, and the high-frequency bias OFF time increases and the frequency of the bias power to be applied is increased. Ikemoto teaches in paeg7 teaches the flow rate of the protective film forming gas is increased as compared with the trench forming step).
Thus, it would have been obvious to one of the ordinary skill in the art at the time the application was filed to have the feature of ramping up one or more processing parameters with routine experiment and optimization in order to control the since the shape of the bottom of the trench according to the teachings of Ikemoto and ‘3603. In re Woodruff, 16 USPQ2d 1935, 1937 (Fed. Cir. 1990). See also In re Boesch, 205 USPQ 215 (CCPA) (discovery of optimum value of result effective variable in known process is ordinarily within skill of art) and In re Aller, 105 USPQ 233 (CCPA 1955) (selection of optimum ranges within prior art general conditions is obvious).
Claim Rejections - 35 USC § 103
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 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.
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 of this title, 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.
Claims 1, 23 are rejected under 35 U.S.C. 103 as being obvious over JP4653603 B2 (herein after ‘3603) in view of Ikemoto et al. (JP 2015162630 A)
Regarding claims 1, 23: ‘3603 teaches in Fig. 7A-7D about a method of plasma etching a substrate to form a feature, the method comprising the steps of:
(a) providing the substrate 102 with a mask 201 formed thereon, the mask having an opening, wherein the substrate is formed from a compound semiconductor material;
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(b) performing a first plasma etch step to anisotropically etch (page 8) the substrate through the opening to produce a partial form of the feature 203 having a bottom surface comprising a peripheral region; and
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(c) performing a second plasma etch step to anisotropically etch (page 9) the bottom surface 203 of the partial form of the feature through the opening while depositing a passivation material 401onto the mask so as to reduce a dimension of the opening (as shown),
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wherein the second plasma etch step comprises ramping a parameter between a beginning and an end of the second plasma etch step, wherein the reduction of the dimension of the opening causes an attenuation in etching of the peripheral region thereby producing a full form of the feature such that the bottom surface includes a central region (bottom surface 402) and an edge region 405, wherein the central region is deeper than the edge region of the bottom surface of the full form of the feature (for clarification, page 9 teaches As the trench etching progresses, a protective film 401 is formed on the trench sidewall 404, and the film thickness gradually increases. The ions of the mixed gas plasma incident on the bottom surface 402 of the trench are partially blocked by the protective film 401. The closer the bottom end 402 is to the trench side wall 404, the smaller the solid angle of ion incidence by the protective film 401, and the lower the etching rate. Since the processing proceeds at a constant etching rate on the surface of the bottom portion 402 where the ion incidence is not shielded, the end portion 405 of the trench bottom surface 402 is rounded), and wherein the parameter includes one or more of a gas mixture composition, a gas ratio, a flow rate, a processing time (For clarification, page 9 teaches The film thickness and shape of the protective film 401 described above can be adjusted by adjusting the amount of reaction product generated by the O2 flow rate ratio and the processing pressure, or by the reaction time of the reaction product by the duty ratio and period of the TM bias, and the side wall. It can be controlled by adjusting the adhesion time. The growth rate of the protective film 401 increases as the O2 flow ratio increases, the processing pressure increases, and the high-frequency bias OFF time increases. Depending on the film thickness of the protective film 401, the region for shielding ion incidence can be adjusted, and the radius of curvature in round processing can be controlled.), an etch time, a plasma source power, a platen power, a bias power applied to the substrate, or a frequency of power (for clarification, page 9 teaches However, in order to improve the controllability of the top round shape applied to the trench upper end portion 204, the frequency of the bias power to be applied is increased) applied.
‘3603 teaches the substrate is silicon except a compound semiconductor material.
Ikemoto teaches in abstract in an analogous art of two step etching process to form a feature while the substrate is a compound semiconductor material Silicon Carbide.
It would have been obvious to one of ordinary skill in the art at the time of the application was filed to havethe material as claimed, since it has been held to be within the general skill of a worker in the art to select a known material on the basis of its suitability for the intended use as a matter of obvious design choice as Ikemoto teaches in page 1 silicon carbide is used for power devices. In re Leshin, 125 USPQ 416.
Claims 1-2, 4-19, 23 are rejected under 35 U.S.C. 103 as being obvious over Ikemoto et al. (JP 2015162630 A) in view of JP4653603 B2 (herein after ‘3603)
Regarding claims 1, 23: Ikemoto teaches in Fig. 3-7 about a method of plasma etching a substrate K to form a feature (trench), the method comprising the steps of:
(a) providing the substrate with a mask M formed thereon, the mask having an opening,wherein the substrate is formed from a compound semiconductor material (mask forming step S1) (Abstract, silicon carbide);
(b) performing a first plasma etch step (trench forming step S2 comprising S22 and/or S22) to anisotropically etch the substrate through the opening to produce a partial form of the feature having a bottom surface comprising a peripheral region (Fig. 4); and
(c) performing a second plasma etch step (trench bottom rounding process) to anisotropically etch the bottom surface of the partial form of the feature through the opening while depositing a passivation material onto the mask so as to reduce a dimension of the opening (page 7 teaches B) The flow rate of the protective film forming gas is increased as compared with the trench forming step), wherein the second plasma etch step comprises ramping a parameter between a beginning and an end of the second plasma etch step, wherein the reduction of the dimension of the opening causes an attenuation in etching of the peripheral region thereby producing a full form of the feature such that the bottom surface includes a central region and an edge region (Fig. 7, page 7 teaches the protective film H formed on the sidewall of the trench T is thicker than in the trench formation step), wherein the central region is deeper than the edge region of the bottom surface of the full form of the feature (Fig. 7), and wherein the parameter includes one or more of a gas mixture composition, a gas ratio, a flow rate (paeg7 teaches The flow rate of the protective film forming gas is increased as compared with the trench forming step), a processing time, an etch time, a plasma source power, a platen power, a bias power applied to the substrate, or a frequency of power applied.
Ikemoto teaches only the flow rate of the protective film forming gas is increased during the trench bottom rounding step.
However ‘3603 teaches during second anisotrophy etching for rounding bottom of the trench in Fig. 7 (d) and page 9, one or more processing parameters like the growth rate of the protective film 401 increases as the O2 flow ratio increases, the processing pressure increases, and the high-frequency bias OFF time increases, the frequency of the bias power to be applied is increased can be increased (thereby ramping).
Thus, it would have been obvious to one of the ordinary skill in the art at the time the application was filed to have the feature of ramping up one or more processing parameters with routine experiment and optimization in order to control the since the shape of the bottom of the trench according to the teachings of Ikemoto and ‘3603. In re Woodruff, 16 USPQ2d 1935, 1937 (Fed. Cir. 1990). See also In re Boesch, 205 USPQ 215 (CCPA) (discovery of optimum value of result effective variable in known process is ordinarily within skill of art) and In re Aller, 105 USPQ 233 (CCPA 1955) (selection of optimum ranges within prior art general conditions is obvious).
Regarding claim 2: Ikemoto teaches in trench bottom rounding step of B) wherein the passivation material is deposited at a deposition rate that increases during the second plasma etch step.
Regarding claim 4: Ikemoto teaches in trench bottom rounding step of B) wherein the parameter that is varied is ramped at an increasing rate of change (page 7, At this time, preferable F6 / F5 is 1-1.39).
Regarding claim 5: Ikemoto teaches in in trench bottom rounding step of B) wherein ramping the parameter comprises ramping the flow rate of a passivation material precursor during the second plasma etch step such that the flow rate of the passivation material precursor is increased during the second plasma etch step (page 7, At this time, preferable F6 / F5 is 1-1.39)
Regarding claim 6: Ikemoto teaches wherein the passivation material precursor comprises an oxygen-containing gas page 7, At this time, preferable F6 / F5 is 1-1.39).
Regarding claim 7: Ikemoto teaches in page 9 about wherein ramping the parameter comprises ramping the bias power applied to the substrate during the second plasma etch step, such that the bias power applied to the substrate is decreased during the second plasma etch step (in the late etching process, the power applied to the base 15 is lowered as compared with the initial etching process.
Regarding claim 8: ‘3630 teaches wherein the passivation material comprises a silicon oxide [page 7].
Regarding claim 9: ‘3630 teaches in wherein the passivation material and the mask are made of substantially the same material (silicon oxide).
Regarding claim 10: Ikemoto and ‘3630 teaches in wherein the second plasma etch step includes using an etch recipe comprising a chlorine-based etchant (Fluorine based etchant).
It would have been obvious to one of ordinary skill in the art at the time of the application was filed to have the etchant as claimed, since it has been held to be within the general skill of a worker in the art to select a known material on the basis of its suitability for the intended use as a matter of obvious design choice. In re Leshin, 125 USPQ 416.
Regarding claim 11: Ikemoto and ‘3630 teaches wherein the chlorine-based etchant comprises Cl2 and/or SiCl4 (Fluorine based etchant).
It would have been obvious to one of ordinary skill in the art at the time of the application was filed to have the etchant as claimed, since it has been held to be within the general skill of a worker in the art to select a known material on the basis of its suitability for the intended use as a matter of obvious design choice. In re Leshin, 125 USPQ 416.
Regarding claim 12: Ikemoto and ‘3630 teaches wherein the bottom surface of the partially formed feature is substantially flat.
Regarding claim 13: Ikemoto and ‘3630 teaches wherein the feature is a trench.
Regarding claim 14: Ikemoto and ‘3630 teaches wherein the central region of the bottom surface of the fully formed feature is substantially flat.
Regarding claim 15: Ikemoto and ‘3630 teaches wherein the edge region of the bottom surface of the fully formed feature comprises a curved surface.
Regarding claim 16: Ikemoto and ‘3630 teaches wherein the edge region forms a rounded corner between the central region of the bottom surface and a sidewall of the fully formed feature.
Regarding claim 17: Ikemoto teaches in abstract wherein the compound semiconductor substrate is a silicon carbide (SiC) wafer.
Regarding claim 18: ‘3630 teaches in page 10 about (d) selectively removing the passivation material from the substrate by wet etching.
Regarding claim 19: Ikemoto and ‘3630 teaches wherein steps (b) and (c) are performed using an inductively coupled plasma (ICP) etch apparatus.
It has been held that to be entitled to weight in method claims, the recited-structure limitations therein must affect the method in a manipulative sense, and not to amount to the mere claiming of a use of a particular structure. Ex parte Pfeiffer, 1962 C.D. 408 (1961).
Response to Arguments
Applicant’s arguments with respect to claim 1 has been considered but are moot because the new ground of rejection does not rely on any reference applied in the prior rejection of record for any teaching or matter specifically challenged in the argument.
Conclusion
THIS ACTION IS MADE FINAL. Applicant is reminded of the extension of time policy as set forth in 37 CFR 1.136(a).
A shortened statutory period for reply to this final action is set to expire THREE MONTHS from the mailing date of this action. In the event a first reply is filed within TWO MONTHS of the mailing date of this final action and the advisory action is not mailed until after the end of the THREE-MONTH shortened statutory period, then the shortened statutory period will expire on the date the advisory action is mailed, and any nonprovisional extension fee (37 CFR 1.17(a)) pursuant to 37 CFR 1.136(a) will be calculated from the mailing date of the advisory action. In no event, however, will the statutory period for reply expire later than SIX MONTHS from the mailing date of this final action.
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/Mohammed Shamsuzzaman/Primary Examiner, Art Unit 2897
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