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 .
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.
Election/Restrictions
Applicant’s election without traverse of claims 1-15 in the reply filed on June 23, 2026 is acknowledged. Claims 16-20 are withdrawn from further consideration pursuant to 37 CFR 1.142(b) as being drawn to a nonelected invention, there being no allowable generic or linking claim.
Claim Rejections - 35 USC § 102
The following is a quotation of the appropriate paragraphs of 35 U.S.C. 102 that form the basis for the rejections under this section made in this Office Action:
A person shall be entitled to a patent unless –
(a)(1) the claimed invention was patented, described in a printed publication, or in public use, on sale or otherwise available to the public before the effective filing date of the claimed invention.
Claims 1, 4, 7-8 and 15 are rejected under 35 U.S.C. 102(a)(1) as being anticipated by Park et al. (US20090081873).
Regarding claim 1, Park discloses a method of etching larger critical dimension (CD) features and smaller CD features into a dielectric material through a single mask using an etch stop (abstract and paragraph 0019), the method comprising: performing an inverse aspect ratio-dependent etch (ARDE) step comprising forming the etch stop on bottom surfaces of the larger CD features within the dielectric material using a first gas mixture, and etching the dielectric material within the smaller CD features using the first gas mixture while the etch stop prevents etching of the larger CD features (a reverse RIE lag reads on an inverse aspect ratio-dependent etch, paragraphs 0016-0019 and Fig. 4); and performing an ARDE step comprising concurrently etching the dielectric material within the larger CD features at a first etch rate using a second gas mixture, and etching the dielectric material within the smaller CD features at a second etch rate slower than the first etch rate using the second gas mixture (paragraph 0020 and Fig. 5).
Regarding claim 4, Park discloses wherein the first gas mixture comprises fluorocarbon (CF) species and hydrofluorocarbon (CHF) species in a first ratio of CF to CHF that is greater than about 0.45 (the etching gas includes CxFy and does not include hydrogen, paragraph 0018); amd wherein the second gas mixture comprises CF species and CHF species in a second ratio of CF to CHF that is less than about 0.25 (the etching gas includes CaHbFc, paragraph 0021).
Regarding claim 7, Park discloses a method of reactive-ion etching (RIE) larger critical dimension (CD) features and smaller CD features into a dielectric material through a single mask using an etch stop (abstract and paragraph 0019), the method comprising: performing an inverse RIE-lag step comprising forming the etch stop on nitride bottom surfaces of the larger CD features within the dielectric material using a first gas mixture comprising fluorocarbon (CF) species and hydrofluorocarbon (CHF) species in a first ratio of CF to CHF, and etching the dielectric material within the smaller CD features using the first gas mixture while the etch stop prevents etching of the larger CD features (a reverse RIE lag reads on an inverse aspect ratio-dependent etch, paragraphs 0016-0019 and Fig. 4); and performing an RIE-lag step comprising concurrently etching the dielectric material within the larger CD features at a first etch rate using a second gas mixture comprising CF species and CHF species in a second ratio of CF to CHF that is lower than the first ratio, and etching the dielectric material within the smaller CD features at a second etch rate slower than the first etch rate using the second gas mixture (the first etching gas does not include hydrogen, paragraph 0019, while the second etching gas includes hydrogen, indicating that the CF/CHF ratio in the second gas mixture is lower than in the first gas mixture, paragraphs 0019-0020).
Regarding claim 8, Park discloses wherein the first ratio is greater than about 0.45 and the second ratio is less than about 0.25 (the first etching gas includes CxFy and does not include hydrogen, paragraph 0018; the second etching gas includes CaHbFc, paragraph 0021).
Regarding claim 15, Park discloses wherein the CD of the larger CD features is greater than four times the CD of the smaller CD features (Fig. 5).
Claim Rejections - 35 USC § 103
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.
This application currently names joint inventors. In considering patentability of the claims the examiner presumes that the subject matter of the various claims was commonly owned as of the effective filing date of the claimed invention(s) absent any evidence to the contrary. Applicant is advised of the obligation under 37 CFR 1.56 to point out the inventor and effective filing dates of each claim that was not commonly owned as of the effective filing date of the later invention in order for the examiner to consider the applicability of 35 U.S.C. 102(b)(2)(C) for any potential 35 U.S.C. 102(a)(2) prior art against the later invention.
Claim 2 is rejected under 35 U.S.C. 103 as being obvious over Park et al. (US20090081873) as applied to claim 1 above.
Regarding claim 2, Park discloses wherein the bottom surfaces on which the etch stop is formed during the inverse ARDE step are bottom surfaces of the larger CD features (the large pattern reads on the larger CD feature, paragraph 0019). Park is silent about wherein the dielectric material comprises nitride. However, Park discloses that the method is used to forming a mask layer pattern having at least first and second openings of different size therein, on an electrically insulating layer (claim 1). Nitrides, such as silicon nitride, are well-known electrically insulating layer in semiconductor processes.
Claim 3 is rejected under 35 U.S.C. 103 as being unpatentable over Park et al. (US20090081873) as applied to claim 1 above, in view of Gohira et al. (US20190252203).
Regarding claim 3, Park is silent about wherein the dielectric material is an ONO stack comprising a plurality of oxide layers separated by nitride layers. However, Park discloses that the method uses plasma etching to form patterned structures on an electrically insulating layer (paragraph 0020 and claim 1). In addition, Gohira teaches that a plasma etching process can be applied to form patterned structures on an ONO stack (abstract). Therefore, it would have been obvious to one of ordinary skill, in the art before the effective filing date of the claimed invention, to apply the plasma etching method of Park to the insulating stack of Gohira, with a reasonable expectation of success. It has been held that combining prior art elements according to known methods to yield predictable results is obvious. See MPEP 2143 I.(A).
Claim 12 is rejected under 35 U.S.C. 103 as being obvious over Park et al. (US20090081873) as applied to claim 7 above, in view of Gohira et al. (US20190252203).
Regarding claim 12, Park is silent about wherein the dielectric material is an ONO stack comprising a plurality of oxide layers separated by nitride layers. However, Park discloses that the method uses plasma etching to form patterned structures on an electrically insulating layer (abstract). In addition, Gohira teaches that a plasma etching process can be applied to form patterned structures on an ONO stack (abstract). Therefore, it would have been obvious to one of ordinary skill, in the art before the effective filing date of the claimed invention, to apply the plasma etching method of Park to the insulating stack of Gohira, with a reasonable expectation of success. It has been held that combining prior art elements according to known methods to yield predictable results is obvious. See MPEP 2143 I.(A).
Allowable Subject Matter
Claims 5-6, 9-11 and 13-14 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.
The following is a statement of reasons for the indication of allowable subject matter:
Regarding claims 5 and 13, the cited prior art of record, taken either alone or in combination, fails to disclose or render obvious a method comprising: clogging openings of the mask corresponding to the smaller CD features to form an additional etch stop after the inverse ARDE step and before the ARDE step so that the second etch rate during the ARDE step is substantially zero, wherein etching the dielectric material during the inverse ARDE step comprises etching the dielectric material within the smaller CD features until reaching an underlying layer, in the context of the instant claim.
Regarding claim 6, the cited prior art of record, taken either alone or in combination, fails to disclose or render obvious a method comprising: performing an additional inverse ARDE step, the intermediate ARDE step comprising forming an intermediate etch stop on bottom surfaces of intermediate CD features and on bottom surfaces of the larger CD features using a third gas mixture, and etching the dielectric material within the smaller CD features using the third gas mixture while the intermediate etch stop prevents etching of the intermediate CD features and the larger CD features, wherein the inverse ARDE step further comprises etching the dielectric material within the intermediate CD features using the first gas mixture while the etch stop prevents etching of the large CD features, in the context of the instant claim.
Regarding claim 9, the cited prior art of record, taken either alone or in combination, fails to disclose or render obvious a method comprising: wherein the first gas mixture comprises trifluoromethane (CHF3) and at least one higher order CF species, the first ratio being about 0.48, and wherein the second gas mixture comprises CHF3 and at least one higher order CF species, the second ratio being about 0.23, in the context of the instant claim.
Regarding claim 10, the cited prior art of record, taken either alone or in combination, fails to disclose or render obvious a method comprising: wherein the inverse RIE-lag step further comprises etching the dielectric material within the smaller CD features using a third gas mixture comprising CF species and CHF species in a third ratio of CF to CHF that is lower than the first ratio and higher than the second ratio after etching the dielectric material using the first gas mixture, in the context of the instant claim.
Regarding claim 11, the cited prior art of record, taken either alone or in combination, fails to disclose or render obvious a method comprising: performing a flash step using a flash gas mixture comprising oxygen to remove the etch stop before the RIE-lag step, in the context of the instant claim.
Regarding claim 14, the cited prior art of record, taken either alone or in combination, fails to disclose or render obvious a method comprising: performing an additional inverse RIE-lag step, the intermediate RIE-lag step comprising forming an intermediate etch stop on nitride bottom surfaces of intermediate CD features and on nitride bottom surfaces of the larger CD features using a third gas mixture comprising CF species and CHF species in a third ratio of CF to CHF that is higher than the first ratio, and etching the dielectric material within the smaller CD features using the third gas mixture while the intermediate etch stop prevents etching of the intermediate CD features and the larger CD features, wherein the inverse RIE-lag step further comprises etching the dielectric material within the intermediate CD features using the first gas mixture while the etch stop prevents etching of the large CD features, in the context of the instant claim.
Conclusion
The prior art made of record and not relied upon is considered pertinent to applicant's disclosure. Raley et al. (US20180358227) discloses a method for etching a dielectric layer with different CDs (about 15nm and about 80nm) using a two-step process comprising a step exhibiting inverse etch lag and a step with etch lag (abstract, and paragraphs 0017 and 0020).
Any inquiry concerning this communication or earlier communications from the examiner should be directed to JIONG-PING LU whose telephone number is (571) 270-1135. The examiner can normally be reached on M-F: 9:00am – 5:00pm. If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Joshua L Allen, can be reached at telephone number (571)270-3176. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300.
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/JIONG-PING LU/
Primary Examiner, Art Unit 1713
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