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 .
Election/Restrictions
Applicant’s election without traverse of Group II (claims 1-11, 19-27) in the reply filed on 06/23/2026 is acknowledged.
Claim Rejections - 35 USC § 112
The following is a quotation of 35 U.S.C. 112(b):
(b) CONCLUSION.—The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the inventor or a joint inventor regards as the invention.
Claims 1-11, 21-27 are rejected under 35 U.S.C. 112(b), second paragraph, as being indefinite for failing to particularly point out and distinctly claim the subject matter which the inventor or a joint inventor regards as the invention.
Claims 1, 21 recites “”wherein molybdenum is not deposited..” has antecedent issues. It should be “molybdenum precursor is not ...”
Claim 21 recites in line 7 “patterning a hard mask layer..” has antecedent issues which should be “patterning the hard mask layer..”
Claim 8 defines “the gap has a width..” is indefinite as it is not clear what it refers to. For examination purpose it will be examined as a width of the via like claim 5.
Claims 2-11, 22-27 are also rejected being dependent on rejected claims 1, 21.
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 19 is rejected under 35 U.S.C. 103 as being obvious over Ho et al (US 2019/0035734 A1).
Regarding claim 19: Ho teaches in Fig. 1-14 about a method for forming an interconnect structure 100, comprising:
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forming a first dielectric layer 104 upon a substrate 102;
etching [0013] the first dielectric layer to form at least one bottom via opening (where via 106 resides);
depositing an electrically conductive material 106 in the at least one bottom via opening;
planarizing [0013] the first dielectric layer to obtain at least one bottom via;
forming a first etch stop layer 108 upon the first dielectric layer 104;
forming a second dielectric layer 110 upon the etch stop layer 108;
etching [0020] the second dielectric layer and the etch stop layer to form at least one via opening (where 112 resides) to the at least one bottom via;
depositing an electrically conductive material 116i n the at least one via opening;
planarizing [0020] the second dielectric layer to obtain a via 112 (Fig. 3);
forming a second etch stop layer 118 upon the second dielectric layer 110;
forming a third dielectric layer (120 or 122 or 120+122+124) upon the second etch stop layer 118;
forming a hard mask layer 126 [0023] upon the third dielectric layer;
etching the hard mask layer, the third dielectric layer, and the second etch stop layer to form a top via opening 136 that exposes the via (Fig. 11);
selectively depositing molybdenum upon the exposed via to form a cap;
depositing a diffusion barrier layer 114 around the cap;
filling the top via opening with an electrically conductive material 136 (Fig. 13); and
planarizing [0044] the third dielectric layer to form the interconnect structure (Fig. 14).
Ho does not explicitly show selectively depositing molybdenum upon the exposed via to form a cap.
However Ho teaches in [0021] metal caps (not shown) may be formed over the conductive lines 112. The metal caps may also be considered as parts of the conductive lines 112 throughout the description. In some embodiments, the metal caps are formed from cobalt (Co), CoWP, CoB, tungsten (W), tantalum (Ta), nickel (Ni), molybdenum (Mo), titanium (Ti), iron (Fe), or alloys thereof. The metal caps may be formed selectively.
Therefore it would have been obvious to one of ordinary skill in the art, at the time of application was filed to realize the method of forming an interconnect structure in order to reduce the resistive-capacitive (RC) delay in signal propagation due to capacitive effects as well as improvements in processes that utilize low-k dielectric materials are desired (Ho, [0001] – [0002]).
Claims 1-4, 9-10, 20 are rejected under 35 U.S.C. 103 as being obvious over Ho et al (US 2019/0035734 A1) in view of Zhang et al (US 2024/0379768 A1).
Regarding claims 1, 3-4: Ho teaches in Fig. 2-3 and [0020] about a method for forming a molybdenum cap upon a via 112, comprising:
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patterning a hard mask layer (108+110) to expose the via 112 through a window (Fig. 2-3, [0020] teaching openings/window);
depositing the molybdenum cap [0021] upon the via using a mixture comprising a carrier gas and a molybdenum precursor;
wherein molybdenum is not deposited upon the hard mask layer, so that a width of the window in the hard mask layer is not reduced in size.
Ho does not teach the molybdenum cap using a mixture comprising a carrier gas and a molybdenum precursor;
wherein molybdenum is not deposited upon the hard mask layer, so that a width of the window in the hard mask layer is not reduced in size.
Zhang teaches in [0093] – [0095], Fig. 2H about using a mixture comprising a carrier gas and a molybdenum precursor (a selective deposition method of cap formation with a mixture of H2 (carrier gas) and WCl5 (tungsten precursor) with a molar ratio 100:1 and the metal precursor can be Molybdenum [0090]) and
wherein molybdenum is not deposited upon the hard mask layer, so that a width of the window in the hard mask layer is not reduced in size ([0005] – [0007] teaches without forming a forming a seam in the via/feature opening and using the mixture of a carrier gas and a molybdenum precursor and therefore would inherently not be deposited upon the hard mask layer).
Therefore it would have been obvious to one of ordinary skill in the art, at the time of applicant was filed to combine Zhang’s teachings to Ho’s metal cap formation process to have the feature as claimed without forming a forming a seam in the via/feature opening and to have a reliable contact structure with low contact resistance (Zhang, [0005] – [0007]).
Regarding claim 9: Ho teaches in Fig. 3 wherein the via contacts one or more bottom vias 106.
Regarding claim 10: Ho teaches in Fig. 3, further comprising depositing a diffusion barrier layer 114 around the molybdenum cap.
Regarding claim 2, 20: Ho does not teach wherein the cap is formed using a mixture of H2 and MoC5 with a molar ratio (H2:MoC5) of 1500:1 or lower.
Zhang teaches in [0093] – [0095], Fig. 2H about a selective deposition method of cap formation with a mixture of H2 and WCl5 with a molar ratio 100:1 and the metal precursor can be Molybdenum [0090].
In the case where the claimed ranges “overlap or lie inside ranges disclosed by the prior art” a prima facie case of obviousness exists. In re Wertheim, 541 F.2d 257, 191 USPQ 90 (CCPA 1976); In re Woodruff, 919 F.2d 1575, 16 USPQ2d 1934 (Fed. Cir. 1990).
Therefore it would have been obvious to one of ordinary skill in the art, at the time of applicant was filed to combine Zhang’s teachings to Ho’s metal cap formation process without forming a forming a seam in the via/feature opening and to have a reliable contact structure with low contact resistance (Zhang, [0005] – [0007]).
Claims 5-8, 11 are rejected under 35 U.S.C. 103 as being obvious over Ho et al (US 2019/0035734 A1) in view of Zhang et al (US 2024/0379768 A1) and further in view of Su et al. (KR 20220134431 A)
Regarding claims 5, 8: Su teaches in Fig. 3 wherein the via has a width of about 5 nanometers to about 30 nanometers (9 nm to 30 nm).
In the case where the claimed ranges “overlap or lie inside ranges disclosed by the prior art” a prima facie case of obviousness exists. In re Wertheim, 541 F.2d 257, 191 USPQ 90 (CCPA 1976); In re Woodruff, 919 F.2d 1575, 16 USPQ2d 1934 (Fed. Cir. 1990).
Regarding claim 6: Su does not explicitly teach wherein the molybdenum cap upon the via has a thickness of at least 2 nanometers.
However Su teaches in Fig. 9b the thickness of the molybdenum cap upon the via has a thickness very thin in compare with the via opening 42 of Fig. 3 which would make it very thin.
Thus, it would have been obvious to one of the ordinary skill in the art at the time the invention was made to use have thickness as claimed with routine experiment and optimization since the thickness of the metal cap depends on the selective deposition method using a precursor in order to control contact resistance according to the teaching of Su and Zhang. 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 7: Su teaches in Fig. 9b wherein the molybdenum cap upon the via has a width of about 3 nanometers to about 200 nanometers (cap 54 is over the via 50 of width 9 nm to 30 nm).
In the case where the claimed ranges “overlap or lie inside ranges disclosed by the prior art” a prima facie case of obviousness exists. In re Wertheim, 541 F.2d 257, 191 USPQ 90 (CCPA 1976); In re Woodruff, 919 F.2d 1575, 16 USPQ2d 1934 (Fed. Cir. 1990).
Regarding claim 11: Su teaches in Fig. 15a further comprising forming a top via 72 upon the molybdenum cap 54.
Therefore it would have been obvious to one of ordinary skill in the art, at the time of applicant was filed to combine Su’s teachings to Ho’s interconnect formation process to have the feature as claimed with/without forming top via upon bottom via by having/not having metal cap in between using a dual damascene structure depending on design choice for contact resistance.
Claims 21, 24-27 are rejected under 35 U.S.C. 103 as being obvious over Su et al. (KR 20220134431 A) in view of Chang et al. (US Patent 10964792 B1)
Regarding claim 21: Su teaches in Fig. 1-9b about a method for forming an interconnect structure, comprising:
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forming a bottom via 30 in a first dielectric layer 28 upon a substrate 24;
forming a via 50 over the bottom via 30 in a second dielectric layer 34 over the first dielectric layer 28;
forming a hard mask layer upon a third dielectric layer over the second dielectric layer;
patterning a hard mask layer to expose the via through a window; and
depositing molybdenum 54 upon the exposed via using a mixture comprising a carrier gas and a molybdenum precursor to form a cap (When the metal cap 54 is deposited, the precursor may include a metal halide (such as WCl5 or a metal organic material Molybdenum and a reducing agent such as H2).;
wherein molybdenum is not deposited upon the hard mask layer, so that a width of the window in the hard mask layer is not reduced in size (Su teaches the metal cap 54 is formed through a selective deposition process, such that the metal cap 54 is not on the exposed surfaces of dielectric materials and also teaches the metal cap 54 is confined within an area directly above the conductive feature 50).
Su does not explicitly talk about forming a hard mask layer upon a third dielectric layer over the second dielectric layer;
patterning a hard mask layer to expose the via through a window.
Cheng teaches in Fig. 8- 11 forming a hard mask layer 244 upon a third dielectric layer 240 over the second dielectric layer 231;
patterning a hard mask layer to expose the via 235A through a window 962A and then forming a metal cap 246A on top of the via.
Therefore it would have been obvious to one of ordinary skill in the art, at the time of applicant was filed to apply Cheng’s method to form the metal cap in Ho’s interconnect formation process to have the feature as claimed and thereby to have selective bottom up metal cap deposition to prevent corrosions of underlying vias/plugs (Cheng, col. 18, lines 43-46).
Regarding claim 24: Su teaches in Fig. 3 wherein the via has a width of about 5 nanometers to about 30 nanometers (9 nm to 30 nm).
In the case where the claimed ranges “overlap or lie inside ranges disclosed by the prior art” a prima facie case of obviousness exists. In re Wertheim, 541 F.2d 257, 191 USPQ 90 (CCPA 1976); In re Woodruff, 919 F.2d 1575, 16 USPQ2d 1934 (Fed. Cir. 1990).
Regarding claim 25: Su does not explicitly teach wherein the molybdenum cap upon the via has a thickness of at least 2 nanometers.
However Su teaches in Fig. 9b the thickness of the molybdenum cap upon the via has a thickness very thin in compare with the via opening 42 of Fig. 3 which would make it very thin.
Thus, it would have been obvious to one of the ordinary skill in the art at the time the invention was made to use have thickness as claimed with routine experiment and optimization since the thickness of the metal cap depends on the selective deposition method using a precursor in order to control contact resistance according to the teaching of Su and Zhang. 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 26: Su teaches in Fig. 9b further comprising depositing a diffusion barrier layer 46 around the molybdenum cap.
Regarding claim 27: Su teaches in Fig. 14 further comprising forming a top via 72 upon the molybdenum cap.
Claims 22-23 are rejected under 35 U.S.C. 103 as being obvious over Su et al. (KR 20220134431 A) in view of Chang et al. (US Patent 10964792 B1) and further in view of
Zhang et al (US 2024/0379768 A1)
Regarding claims 22-23: Zhang teaches in [0093] – [0095], Fig. 2H about wherein a molar ratio between the carrier gas and the molybdenum precursor is about 2000:1 or lower.
(Zhang teaches in [0093] – [0095], Fig. 2H about a selective deposition method of cap formation with a mixture of H2 and WCl5 with a molar ratio 100:1 and the metal precursor can be Molybdenum [0090]).
In the case where the claimed ranges “overlap or lie inside ranges disclosed by the prior art” a prima facie case of obviousness exists. In re Wertheim, 541 F.2d 257, 191 USPQ 90 (CCPA 1976); In re Woodruff, 919 F.2d 1575, 16 USPQ2d 1934 (Fed. Cir. 1990).
Therefore it would have been obvious to one of ordinary skill in the art, at the time of applicant was filed to combine Zhang’s teachings to Su’s metal cap formation process without forming a forming a seam in the via/feature opening and to have a reliable contact structure with low contact resistance (Zhang, [0005] – [0007]).
Conclusion
Any inquiry concerning this communication or earlier communications from the examiner should be directed to MOHAMMED SHAMSUZZAMAN whose telephone number is (571)270-1839. The examiner can normally be reached Monday-Friday 7 am -4 pm EST.
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/Mohammed Shamsuzzaman/Primary Examiner, Art Unit 2897
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