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 .
Status of the Claims
This is a final office action in response to the applicant’s arguments and remarks filed on 03/09/2026. Claims 1-18 are pending in the current office action. Claim 18 remains withdrawn.
Status of the Rejection
All 35 U.S.C. § 103 rejections from the previous office action are substantially maintained.
Drawings
The drawing objections are withdrawn in view of applicant’s arguments, therefore the drawings filed on 05/17/2023 are accepted.
Claim Rejections - 35 USC § 103
The text of those sections of Title 35, U.S. Code not included in this action can be found in a prior Office action.
Claims 1-17 are rejected under 35 U.S.C. 103 as being unpatentable over Saitoh et al. (US-20160064245-A1) in view of Shimizu et al. (US-20190362983-A1).
Regarding Claim 1, Saitoh teaches an etching method (Paragraph [0002] an etching method taught) comprising:
(a) providing a substrate on a substrate support in a chamber, the substrate including a first region having a multilayer film in which a silicon oxide film and a silicon nitride film are alternately stacked, a second region having a single-layer silicon oxide film, and a mask on the first region and the second region (Paragraph [0017] processing target provided with "a first region including a multi-layer film formed by providing a silicon oxide film and a silicon nitride film alternately, and a second region having a single silicon oxide film" that has a mask over both regions);
(b) etching the substrate with a first plasma generated from a first process gas (Paragraphs [0017-0018] plasma is generated from a second processing gas that etches the substrate); and
(c) etching the substrate with a second plasma generated from a second process gas different from the first process gas (Paragraphs [0017-0018] plasma is generated from a first processing gas that etches the substrate. Paragraphs [0065-0091] example provided where first and second processing gases are different),
wherein the first process gas contains a Cv1Fw1 (v1 is an integer of 2 or more, and w1 is an integer of 1 or more) gas (Paragraph [0057] second processing gas includes a fluorocarbon gas. Paragraph [0060] C4F8 can be included in the second processing gas), and
the second process gas contains a Cx1Hy1Fz1 gas (Paragraph [0056] first processing gas includes a hydrofluorocarbon gas. Paragraph [0067] CH2F2 is provided as an example).
Saitoh fails to teach that the gas Cx1Hy1Fz1 has an unsaturated bond and that x1 is an integer of 2 or more, and y1 and z1 are integers of 1 or more. Saitoh fails to teach that the gas Cv1Fw1 contains an unsaturated bond.
While Saitoh teaches exemplary gases that meet some of the claim limitations as outlined above, Saitoh provides a broad teaching that the first processing gas includes a hydrofluorocarbon (Paragraph [0056]) and the second processing gas includes a fluorocarbon (Paragraph [0057]).
Shimizu teaches methods related to etching silicon oxide and silicon nitride (Paragraph [0002]). Shimizu teaches the use of C3H2F4 and C3F6 to selectively etch silicon oxide and silicon nitride layers (Paragraph [0020]). Shimizu teaches that the process gases that provide ion containing fluorine aid in the etching of oxides while the process gases that provide ions containing hydrogen aid in the etching of nitrides (Paragraph [0020]).
It would have been obvious to one of ordinary skill in the art to have modified the method of Saitoh by selecting as the fluorocarbon gas to be included within the claimed first process gas, C3F6, and selecting as the hydrofluorocarbon gas to be included within the claimed second process gas, C3H2F4, as taught by Shimizu. With this modification all the instant limitations would be met, as these compounds each contain an unsaturated bond and have chemical formula that meet the required formula required by the claim.
This modification would have been the simple substitution of one fluorocarbon suitable for a process of etching silicon oxide and silicon nitride with another, and the simple substitution of one hydrofluorocarbon suitable for a process of etching silicon oxide and silicon nitride with another. The simple substitution of one known element for another is likely to be obvious when predictable results are achieved. See MPEP §2143(B). Furthermore, the selection of a known material, which is based upon its suitability for the intended use, is within the ambit of one of ordinary skill in the art. See MPEP § 2144.07.
Regarding Claim 2, modified Saitoh teaches all the limitations of claim 1, as outlined above. Saitoh further teaches that the method further comprising:(d) repeating (b) and (c) alternately (Paragraph [0006] the two steps are alternately repeated).
Regarding Claim 3, modified Saitoh teaches all the limitations of claim 1, as outlined above. Saitoh fails to teach wherein the first process gas further contains a Cx2Hy2Fz2 (x2 is an integer of 2 or more, and y2 and z2 are integers of 1 or more) gas containing an unsaturated bond, the second process gas further contains a Cv2Fw2 (v2 is an integer of 2 or more, and w2 is an integer of 1 or more) gas containing an unsaturated bond.
Saitoh teaches that the first and second processing gases may include additional gases (Paragraph [0041]) but fails to teaches the gases required by the instant limitation.
Shimizu teaches the use of C3H2F4 and C3F6 together to selectively etch silicon oxide and silicon nitride layers (Paragraph [0020]).
It would have been obvious to one of ordinary skill in the art to have modified the method of modified Saitoh by including C3H2F4 within the claimed first process gas and including C3F6 within the claimed second process gas.
One of ordinary skill in the art would have been motivated to make this modification because Shimizu teaches that the ratio of process gas species that can provide ions containing fluorine, that will etch oxides, and ions that contain hydrogen, that will etch nitride, can be managed to control the etch selectivity can create the desired profile in the etched features (Paragraph [0020]), and therefore by including both gases one would be able to modify the flow rates delivering those gases to control the ratio of ions provided during (b) and (c) in order to form the desired profile in the etched features. Additionally, this modification can be considered the combination of prior art elements according to known methods to yield predictable results. Saitoh teaches a method for etching silicon oxide and silicon nitride and Shimizu teaches that the use of these two gases together is suitable for etching those materials. This combination would have had the predictable result of supplying gases capable of etching silicon oxide and silicon nitride. See MPEP 2143(A)(I).
Modified Saitoh, as outlined above, fails to teach that a ratio of a flow rate of the Cv1Fw1 gas to a flow rate of the Cx2Hy2Fz2 gas is greater than a ratio of a flow rate of the Cv2Fw2 gas to a flow rate of the Cx1Hy1Fz1 gas.
Shimizu teaches that during the etching process C3H2F4 and C3F6 can be each be supplied with a flow rate of 200 to 1000 sccm (Paragraphs [0034-0035]).
It would have been obvious to one of ordinary skill in the art to have selected a flow rate for C3F6 and a flow rate for C3H2F4, for both the first process gas and the second process gas, at a level within the disclosed range of 200 to 1000 sccm, including at amounts that overlap with the claimed range where the flow rate ratio of C3F6 to C3H2F4 is greater in first process gas than in the second process gas. It has been held that obviousness exists where the claimed ranges overlap or lie inside ranges disclosed by the prior art. See MPEP 2144.05 (I). One of ordinary skill in the art would have been motivated to make this modification and selection because: Saitoh teaches that by alternating two etching processes, that have different etching rates and rates of forming a protective film during etching, it is possible to improve the vertically and equalize the depth etched in the first and second region (Paragraphs [0018-0021]). Shimizu teaches that the ratio of process gas species that can provide ions containing fluorine, that will etch oxides, and ions that contain hydrogen, that will etch nitride, can be managed to control the etch selectivity can create the desired profile in the etched features (Paragraph [0020]). Therefore, one of ordinary skill in the art would be motivated to select flow rates for the gases that would suitable for providing ions for etching the layer being etched in the first region, while also enabling the etching of the desired depth and verticality in the both features etched.
Regarding Claim 4, modified Saitoh teaches all the limitations of claims 1 and 3, as outlined above.
Modified Saitoh fails to explicitly teach wherein the ratio of the flow rate of the Cv1Fw1 gas to the flow rate of the Cx2Hy2Fz2 gas is 1 or more and 2 or less.
However, Shimizu teaches that during the etching process C3H2F4 and C3F6 can be each be supplied with a flow rate of 200 to 1000 sccm (Paragraphs [0034-0035]).
It would have been obvious to one of ordinary skill in the art to have selected a flow rate for C3H2F4 and to have selected a flow rate for C3F6 within the disclosed range of 200 to 1000 sccm for each, including at amounts that such that they overlap with the claimed range where the ratio of the flow rate of C3F6 to the flow rate of C3H2F4 is 1 or more and 2 or less. It has been held that obviousness exists where the claimed ranges overlap or lie inside ranges disclosed by the prior art. See MPEP 2144.05 (I).
Regarding Claim 5, modified Saitoh teaches all the limitations of claims 1 and 3, as outlined above.
Modified Saitoh fails to explicitly teach wherein the ratio of the flow rate of the Cv2Fw2 gas to the flow rate of the Cx1Hy1Fz1 gas is less than 1.
However, Shimizu teaches that during the etching process C3H2F4 and C3F6 can be each be supplied with a flow rate of 200 to 1000 sccm (Paragraphs [0034-0035]).
It would have been obvious to one of ordinary skill in the art to have selected a flow rate for C3H2F4 and to have selected a flow rate for C3F6 within the disclosed range of 200 to 1000 sccm for each, including at amounts that such that they overlap with the claimed range where the ratio of the flow rate of C3F6 to the flow rate of C3H2F4 is less than 1. It has been held that obviousness exists where the claimed ranges overlap or lie inside ranges disclosed by the prior art. See MPEP 2144.05 (I).
Regarding Claims 6 and 7, modified Saitoh teaches all the limitations of claim 1 as outlined above. Shimizu further teaches wherein the Cv1Fw1 gas contains a fluoromethyl group, as required by claim 6, and wherein the Cv1Fw1 gas contains at least one of C4F8 or C3F6 (Paragraph [0020] C3F6, which contains a fluoromethyl group, is included. See the rejection of claim 1 above).
Regarding Claims 8 and 9, modified Saitoh teaches all the limitations of claim 1 as outlined above. Shimizu further teaches wherein the Cx1Hy1Fz1 gas contains a fluoromethyl group, as required by claim 8, and wherein the Cx1Hy1Fz1 gas contains at least one of C3H2F4 or C4H2F6, as required by claim 9 (Paragraph [0020] C3H2F4, which contains a fluoromethyl group, is included. See the rejection of claim 1 above).
Regarding Claim 10, modified Saitoh teaches all the limitations of claim 1 as outlined above. Shimizu further teaches wherein the Cv1Fw1 gas contains C3F6, and the Cx1Hy1Fz1 gas contains C3H2F4 (Paragraph [0020] C3F6 and C3H2F4 are included, see the rejection of claim 1 above).
Regarding Claim 11, modified Saitoh teaches all the limitations of claim 1 as outlined above.
Modified Saitoh fails to explicitly teach wherein a pressure in the chamber in (b) is higher than a pressure in the chamber in (c).
However, Saitoh teaches that the range of 20-100mT is a suitable pressure for (b) and (c) (Paragraphs [0077] and [0090]).
It would have been obvious to one of ordinary skill in the art to have selected and incorporated a pressure for (b) and a pressure for (c) at levels within the disclosed range of 20-100mT, including at amounts that overlap with the claimed range the pressure of (b) is higher than the pressure of (c). It has been held that obviousness exists where the claimed ranges overlap or lie inside ranges disclosed by the prior art. See MPEP 2144.05 (I).
Regarding Claims 12 and 13, modified Saitoh teaches all the limitations of claim 1 as outlined above.
Modified Saitoh fails to explicitly teach wherein a processing time of (b) is longer than a processing time of (c), as required by claim 12, and that a ratio of the processing time of (b) to the processing time of (c) is more than 1 and 3 or less, as required by claim 13.
However, Saitoh teaches that the range of 180-600 seconds is a suitable processing time for (b) and (c) (Paragraphs [0078] and [0091]).
It would have been obvious to one of ordinary skill in the art to have selected and incorporated a processing time for (b) and a processing time for (c) at levels within the disclosed range of 180-600 seconds, including at amounts that overlap with the claimed range where the processing time of (b) is higher than the processing time of (c), as required by claim 12, and the claimed range where the ratio of the processing time of (b) to the processing time of (c) is more than 1 and 3 or less. It has been held that obviousness exists where the claimed ranges overlap or lie inside ranges disclosed by the prior art. See MPEP 2144.05 (I).
Regarding Claim 14, modified Saitoh teaches all the limitations of claim 1 as outlined above.
Saitoh fails to teach wherein an aspect ratio of a recess formed in the first region and an aspect ratio of a recess formed in the second region in the substrate after the etching method has been applied are equal to or more than 10.
Shimizu teaches that features can be formed that have an aspect ratio of 20:1 to 100:1 (Paragraph [0009]).
It would have been obvious to one of ordinary skill in the art to have modified the method of modified Saitoh by forming the recessing such that they had an aspect ratio of 20:1 to 100:1 as taught by Shimizu.
This modification would have been obvious as it would have been the combination of prior art elements according to known methods to yield predictable results. The combination would have had the predictable result of providing a suitable aspect ratio for the features that are etched. See MPEP 2143(I)(A).
Regarding Claim 15, modified Saitoh teaches all the limitations of claim 1 as outlined above. Saitoh further teaches wherein at least one of the first process gas or the second process gas further contains an oxygen-containing gas (Paragraph [0041] second processing gas may include an oxygen-containing gas).
Regarding Claim 16, modified Saitoh teaches all the limitations of claim 1 as outlined above. Saitoh further teaches wherein at least one of the first process gas or the second process gas further contains an inert gas (Paragraph [0041] second processing gas may include a noble gas).
Regarding Claim 17, modified Saitoh teaches all the limitations of claim 1 as outlined above. Saitoh further teaches wherein the mask contains at least one of carbon or boron (Paragraph [0027] the mask can be formed of amorphous carbon or an organic polymer).
Response to Arguments
As noted in the Drawing section, applicant's arguments filed on 03/09/2026 with respect to the objections to the drawings have been fully considered and are persuasive. The objections to the drawings have been withdrawn.
Applicant’s arguments, see Remarks Pg. 3-5, filed 03/09/2026, with respect to the 35 U.S.C. § 103 rejection have been fully considered and are not persuasive.
Applicant argues that there is no suggestion to substitute the individual gases taught by Saitoh with the gases taught by Shimizu, and that the modification outlined in the rejection would render the invention of Saitoh unsuitable for its intended purpose.
Examiner respectfully disagrees. Saitoh teaches examples of gases that can be used in the first and second process gases in Paragraphs [0039-0040], [0056], and [0060-0061] however Saitoh teaches in these sections that alternative gases, as well as additional, can be used within the first and second process gases. In Paragraphs [0056-0057] Saitoh teaches that the first processing gas includes a hydrofluorocarbon and a plasma of a hydrofluorocarbon has a higher etching rate for silicon nitride than silicon oxide, while the second processing gas includes a fluorocarbon and the plasma of a fluorocarbon has a higher etching rate for silicon oxide than silicon nitride. Further, Shimizu teaches that the cited gases are suitable for etching oxide and nitride layers, and that the gases provided within the singular process gas taught by Shimizu have differing roles: where the process gases that provide ion containing fluorine aid in the etching of oxides while the process gases that provide ions containing hydrogen aid in the etching of nitrides (Paragraph [0020]).
Examiner takes the position that one of ordinary skill in the art would have been able to combine these teachings to replace each of the gases taught by Saitoh with the gases taught by Shimizu, as outlined in the rejection, with a reasonable expectation of success as the gases taught by Shimizu are taught to have similar roles (i.e. supplying particular types of ions that would enable increased etch rates for particular materials) as the process gases used in the method of Saitoh.
While Shimizu teaches a single etching process and the use of a gas mixture within that process, the test for obviousness is not whether the features of a secondary reference may be bodily incorporated into the structure of the primary reference; nor is it that the claimed invention must be expressly suggested in any one or all of the references. Rather, the test is what the combined teachings of the references would have suggested to those of ordinary skill in the art. See In re Keller, 642 F.2d 413, 208 USPQ 871 (CCPA 1981). In this situation, it is not necessary to incorporate the full mixture of gases taught by Shimizu, or the use of a single etching step taught by Shimizu, into the method of Saitoh. Instead, as outlined in the rejection above, the specific individual gases taught by Shimizu can be incorporated into the method of Saitoh to replace specific individual gases within the method.
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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/A.K.L./Examiner, Art Unit 1713 /DUY VU N DEO/Primary Examiner, Art Unit 1713
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