DETAILED ACTION
Status of Claims
As of the amendment filed 6/22/26, no claims have been added or canceled, and claims 1, 9, and 15 have been amended. Therefore, claims 1-20 remain pending, with claims 1, 9, and 15 being independent.
Request for Continued Examination
The request for continued examination under 37 CFR 1.114, including the fee set forth in 37 CFR 1.17(e) and a submission, filed on 6/22/26 is accepted.
Response to Arguments
Applicant’s arguments dated 6/22/26 with respect to claims 1-14 have been fully considered and are persuasive. The rejection of claims 1-14 has been withdrawn. However, Applicant's arguments with respect to claims 15-20 have been fully considered but they are not persuasive. As explained in the rejection below, siliciding interconnects is known and obvious for improving the robustness of the metal cap. It would logically have happened between the steps shown in figure 7 and figure 8. Siliciding would consume the top part of the metal cap, thus the silicide is in contact with the metal cap and, since it would only be partial consumption, there would also be an interface between the silicide and the metal cap.
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.
Claim(s) 15-20 are rejected under 35 U.S.C. 103 as being unpatentable over Lin (US 2023/0048536) in view of Yu (US 8143162).
As to claim 15, Lin teaches a semiconductor structure (fig. 14), comprising:
a first dielectric layer (24) disposed over a substrate ( [0016]);
a first metal pattern (30) disposed in the first dielectric layer (24, [0018]);
a metal cap (32) disposed over the first metal pattern (30, [0019]);
a composite etch stop layer (34) disposed on the first dielectric layer (24) and in contact with the metal silicide pattern ([0022]).
Lin does not explicitly teach a metal silicide pattern disposed on the metal cap and in contact with the metal cap with an interface between the metal silicide pattern and the metal cap, wherein opposite sidewalls of the metal silicide pattern and opposite sidewalls of the metal cap are laterally encapsulated by the first dielectric layer.
However, At the stage shown in figures 6 and 7, the metal cap is thinned (32 of fig. 6) and regrown (56 of fig. 7, [0029] and [0031]). At this point in the process, siliciding the metal cap would have been obvious so as to improve the robustness of the metal cap (col. 4:44-48 of the Yu reference shows that a silicided metal cap is known in the art).
Furthermore, Lin shows the dielectric layer (24) disposed along opposite sidewalls of the first metal pattern (30) and the metal cap (32/56, fig. 7). During the siliciding process, Yu shows the metal cap being consumed by the silicide layer (see figs. 6A and 6B). That is, the height of the metal cap does not change when its top surface is silicided. Thus, the dielectric layer would still be disposed along opposite sidewalls of the first metal pattern, the metal cap metal cap, and the silicide.
Finally, since siliciding would partially consume the top part of the metal cap, the silicide is in contact with the metal cap and there would also be an interface between the silicide and the metal cap.
As to claim 16, Lin further teaches a top surface of the metal silicide pattern is flushed with the a surface of the first dielectric layer (fig. 2, see discussion in claim 9 about consumption of the metal cap when siliciding and how it doesn’t affect the height).
As to claim 17, Lin further teaches the metal cap comprises Co, Ni, Ti, W, Pt or a combination thereof ([0019]).
As to claim 18, Lin further teaches the composite etch stop layer comprises at least two of SiOC, SiCN, SiC, SiN, AIN, Al2O3 and a combination thereof ([0022]).
As to claim 19, Lin further teaches a dielectric constant of the first dielectric layer (24) is lower than a dielectric constant of the lowermost etch stop layer (34) of the composite etch stop layer by about 10-40%([0016] and [0022]).
The materials of the dielectric layer and the ESL are different from each other for etch selectivity purposes. Lin teaches the dielectric layer is PSG, BSGB, PSG, FSG, silicon oxide or the like ([0016]), while the bottom layer of a sample composite ESL layer is an aluminum oxide material ([0022]). Aluminum oxide is known to have a higher dielectric constant than doped silicon oxide. Determining the proper concentrations would have been obvious so as to optimize an etch selectivity of the dielectric layer with respect to the ESL layer. If that leads to a difference in dielectric constants between 10-40%, then that is the result of ordinary skill in the art and not innovation.
As to claim 20, Yu further teaches a sidewall of the metal silicide pattern is flushed with a sidewall of the first metal pattern (fig. 6B).
Allowable Subject Matter
Claims 1-14 are allowed. The following is an examiner’s statement of reasons for allowance: The prior art taken either singularly or in combination fails to anticipate or fairly suggest the limitations of the claims listed above in such a manner that a rejection under 35 U.S.C. 102 or 103 would be proper.
The prior art fails to teach a combination of all of the features in the claims. As to claims 1 and 9, Lin teaches forming a recess in the metal cap by etching [0029] and siliciding the metal cap within the recess (see Yu). However, these steps are done after the formation of the composite etch stop layer, not before as claimed. Changing the step order would not have been obvious since the whole reason for the etching of the metal cap is inadvertent and due to overetching of the etch stop layer.
The remaining claims are allowed at least because they depend from allowed claims 1 or 9.
Any comments considered necessary by applicant must be submitted no later than the payment of the issue fee and, to avoid processing delays, should preferably accompany the issue fee. Such submissions should be clearly labeled “Comments on Statement of Reasons for Allowance.”
Conclusion
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Any inquiry concerning this communication or earlier communications from the examiner should be directed to KAREN M KUSUMAKAR whose telephone number is (571)270-3520. The examiner can normally be reached on Monday – Friday from 7:30a – 4:30p EST.
If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Fernando Toledo can be reached on 571-272-1867. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300.
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/KAREN KUSUMAKAR/
Primary Examiner, Art Unit 2897
6/25/26
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