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 .
Continued Examination Under 37 CFR 1.114
A request for continued examination under 37 CFR 1.114, including the fee set forth in 37 CFR 1.17(e), was filed in this application after final rejection. Since this application is eligible for continued examination under 37 CFR 1.114, and the fee set forth in 37 CFR 1.17(e) has been timely paid, the finality of the previous Office action has been withdrawn pursuant to 37 CFR 1.114. Applicant's submission filed on September 18, 2026 has been entered.
Claims Status
Claims 1,4, 6, 8, 10 are rejected. Claim 11 is withdrawn.
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 (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.
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.
The factual inquiries for establishing a background for determining obviousness under 35 U.S.C. 103 are summarized as follows:
1. Determining the scope and contents of the prior art.
2. Ascertaining the differences between the prior art and the claims at issue.
3. Resolving the level of ordinary skill in the pertinent art.
4. Considering objective evidence present in the application indicating obviousness or nonobviousness.
Claims 1, 6, 8, 10 are rejected under 35 U.S.C. 103 as being unpatentable over Brown (U.S. 2012/0247505), Heo et al (U.S. 2003/0203632), and Lee et al (U.S. 2022/0115248).
Regarding claim 1. Brown et al discloses an etching method (Abstract; claims 16-25) comprising: selectively etching a silicon nitride layer in a reactor (FIG. 6A, item 640) against a silicon oxide layer (Abstract), under pressurization conditions ([0040], i.e. Pressure for the steam water vapor mixture can be in the range from 0.2 to 2.0 MPa), using an etching composition ([0043], i.e. a treatment liquid) including a phosphoric acid based on a total weight of the etching composition ([0040], i.e. composition of 85% phosphoric acid by weight),
wherein the etching composition does not include a compound containing a silicon atom ([0030], i.e. The chemical reactions for etching silicon nitride: Si3N4+4H3PO4+12H2O → 3Si(OH)4+4NH4H2PO4 ; [0040]; claims 16-25; examiner makes note that 4H3PO4+12H2O does not include a compound containing a silicon atom).
wherein the etching composition ([0043], i.e. a treatment liquid) is maintained in a liquid phase ([0043], i.e. a treatment liquid) under the pressurization conditions are 2 to 20 atm ([0040], i.e. mixture can be in the range from 0.2 to 2.0 MPa) during the selective etching ([0027], i.e. aqueous phosphoric acid is utilized to illustrate a treatment liquid in the present invention),
wherein the etching method is performed at a temperature of 150C to 300C ([0043, i.e. The inventors found that the treatment liquid can be advantageous at a range of 160 to 200 degrees C. and preferably about 180 degrees C. for a treatment liquid using aqueous phosphoric acid), and
wherein the following (A) to (C) are satisfied:
(A) an etching rate of the silicon nitride layer is 50 A/min or more ([0036], i.e. Silicon nitride etch processes are slow (30-60 Angstrom/min, or A/min) in hot phosphoric acid at 16.degree. C. If the etch rate of silicon nitride can be increased to over 180 A/min),
(B) an etching rate of the silicon oxide layer is 0 to 10 A/min ([0036]; claims 16-18; examiner makes note ((etch rate silicon nitride)/(etch rate of silicon oxide)=(selectivity of silicon nitride to silicon oxide) that etch rate of silicon nitride is 30- over 180 Angstrom/min and with a selectivity of silicon nitride to silicon oxide of 10:1 to 1000:1 would give an silicon oxide rate of 0.18-3 A/min), and
(C) an etching selectivity of the silicon nitride layer to the silicon oxide layer is 2 to 400 (claims 16-18; i.e. etch selectivity ratio is in the range from 10:1 to 1000:1).
Brown et al fails to explicitly disclose wherein the etching composition includes 30 to 70 wt% of the phosphoric acid, while selectively etching the silicon nitride layer against the silicon oxide layer in the reactor, the reactor itself is pressurized and maintained at a pressure and heated to such that boiling of the etching composition is suppressed and the etching composition is maintained in a liquid phase in the reactor
However, Heo et al teaches wherein the etching composition includes 30 to 70 wt% of the phosphoric acid ([Abstract]; water solution containing phosphoric acid (H3PO4) of a concentration of 50-70% by weight).
Since Brown et al and Heo et al discloses etching composition of 85% for silicon nitride, it would have been obvious to one having ordinary skill in the art of semiconductors before the effective filing date of the claimed invention to have combined the etching method as disclosed to modify Brown et al with the teachings of wherein the etching composition includes 30 to 70 wt% of the phosphoric acid as disclosed by Heo et al. The use of water solution containing phosphoric acid of a concentration of 50-70% by weight in Heo et al provides for the etch rate of the nitride film is increased, and the selectivity between the nitride film and an oxide film is kept very high (Heo et al, [Abstract]).
Brown et al and Heo et al fails to explicitly disclose while selectively etching the silicon nitride layer against the silicon oxide layer in the reactor, the reactor itself is pressurized and maintained at a pressure and heated to such that boiling of the etching composition is suppressed and the etching composition is maintained in a liquid phase in the reactor
However, Lee et al teaches while selectively etching the silicon nitride layer against the silicon oxide layer ([0005]) in the reactor (FIG. 5, item 400), the reactor itself is pressurized ([0085]) and maintained ([0085]) at a pressure ([0085]) and heated (FIG. 5, item 600, [0109]) to such that boiling of the etching composition (FIG. 5, item L) is suppressed and the etching composition is maintained in a liquid phase (FIG. 5, item L) in the reactor ([0005], i.e. concentration of the etchant constant and have completed the present invention by finding that when pressurizing an etchant storage chamber and/or an etching chamber, the vaporization of the etchant can be prevented)
Brown et al ([0040]-[0043]) and Lee et al ([0079]) discloses keeping the etchant under a pressure.
Since Brown et al, Heo et al and Lee et al teach selectively etching silicon nitride film to silicon oxide film, it would have been obvious to one having ordinary skill in the art of semiconductors before the effective filing date of the claimed invention to have combined the etching method as disclosed to modify Brown et al and Heo et al with the teachings of while selectively etching the silicon nitride layer against the silicon oxide layer in the reactor, the reactor itself is pressurized and maintained at a pressure and heated to such that boiling of the etching composition is suppressed and the etching composition is maintained in a liquid phase in the reactor as disclosed by Lee et al. The use of concentration of the etchant constant and have completed the present invention by finding that when pressurizing an etchant storage chamber and/or an etching chamber, the vaporization of the etchant can be prevented in Lee et al provides for a selectivity of the silicon nitride film to the silicon oxide film can be remarkably improved (Lee et al, [0005]).
Regarding claim 6. Brown et al, Heo et al and Lee et al discloses all the limitation of the etching method of claim 1 above.
Brown et la further discloses wherein the etching composition has an etching selectivity of 10 to 400 (claims 16-18; i.e. etch selectivity ratio is in the range from 10:1 to 1000:1)
Regarding claim 8. Brown et al, Heo et al and Lee et al discloses all the limitations of the etching method of claim 1 above.
Brown et al further discloses wherein an object to be etched of the etching composition is a wafer (Claim 16) in which both silicon nitride layer (Claim 16) and silicon oxide layer (Claim 16) are exposed to a surface (Claim 16) or a wafer having a stack structure having the silicon nitride layer and the silicon oxide layer as a unit layer.
Regarding claim 10. Brown et al, Heo et al and Lee et al discloses all the limitations of the etching method of claim 1 above.
Brown et al further discloses a method of manufacturing a semiconductor device ([0027]) using the etching method of claim 1 (claims 14-16).
Allowable Subject Matter
Claim 4 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.
Response to Arguments
Applicant's arguments filed September 18, 2026 have been fully considered but they are not persuasive.
On page 5 of applicant’s remarks, applicant appears to argue that Brown does not teach or suggest pressurizing the reactor itself to suppress boiling.
Examiner respectfully points out that Brown et al was not used to teach pressurizing the reactor itself to suppress boiling and that Lee et al discloses applicant’s amended claim limitation. In response to applicant's arguments against the references individually, one cannot show nonobviousness by attacking references individually where the rejections are based on combinations of references. See In re Keller, 642 F.2d 413, 208 USPQ 871 (CCPA 1981); In re Merck & Co., 800 F.2d 1091, 231 USPQ 375 (Fed. Cir. 1986).
On page 8 of applicants remarks, applicant appears to argue that brown fails to disclose the entire interior of the reactor is pressurized.
In response to applicant's argument that the references fail to show certain features of the invention, it is noted that the features upon which applicant relies (i.e., the entire interior of the reactor) are not recited in the rejected claim(s). Although the claims are interpreted in light of the specification, limitations from the specification are not read into the claims. See In re Van Geuns, 988 F.2d 1181, 26 USPQ2d 1057 (Fed. Cir. 1993).
Furthermore, Lee et al discloses applicant’s argued limitation.
On page 9 of applicant’s remarks, applicant appears to argue that Heo et al does not disclose or suggest the reactor itself is pressurizing the reactor itself to 2 to 20 atm at the high temperature of 1500C to 3000C so as to suppress boiling and maintain an etching composition in the liquid phase.
Examiner respectfully points out that Heo et al was not used to disclose this argued claim limitation and that Brown et al and Lee et al disclose applicant’s argued limitation. In response to applicant's arguments against the references individually, one cannot show nonobviousness by attacking references individually where the rejections are based on combinations of references. See In re Keller, 642 F.2d 413, 208 USPQ 871 (CCPA 1981); In re Merck & Co., 800 F.2d 1091, 231 USPQ 375 (Fed. Cir. 1986).
On page 10 of applicant’s remarks, applicant appears to argue that there is no motivation to combine Brown et al and Heo et al.
In response to applicant’s argument that there is no teaching, suggestion, or motivation to combine the references, the examiner recognizes that obviousness may be established by combining or modifying the teachings of the prior art to produce the claimed invention where there is some teaching, suggestion, or motivation to do so found either in the references themselves or in the knowledge generally available to one of ordinary skill in the art. See In re Fine, 837 F.2d 1071, 5 USPQ2d 1596 (Fed. Cir. 1988), In re Jones, 958 F.2d 347, 21 USPQ2d 1941 (Fed. Cir. 1992), and KSR International Co. v. Teleflex, Inc., 550 U.S. 398, 82 USPQ2d 1385 (2007). In this case, Brown et al and Heo et al discloses etching composition of 85% for silicon nitride.
Conclusion
The prior art made of record and not relied upon is considered pertinent to applicant's disclosure.
Lim et al (U.S. 2022/0235267) NON-PHOSPHORIC ACID-BASED SILICON NITRIDE FILM ETCHING COMPOSITION AND ETCHING METHOD USING THE SAME.
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/S.E.B./Examiner, Art Unit 2815
/JOSHUA BENITEZ ROSARIO/Supervisory Patent Examiner, Art Unit 2815
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