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
Claims 16-22 and 25-37 are pending in the application and are currently being examined. Claims 16, 17, 19, 21, 25 and 29 have been amended. Claims 1-15 and 23-24 have been canceled. New claims 36 and 37 have been added.
Response to Arguments
Applicant’s arguments, see pages 10 and, filed 6/25/26, with respect to claims 16-19 have been fully considered and are persuasive. The rejection of 2/25/26 has been withdrawn. Examiner agrees claims 16-19 are allowable after further search and consideration.
Applicant’s arguments, see pages 10 and 11 of Remarks, filed 6/25/26, with respect to the rejection(s) of claim(s) 21-22 and 25-37 under 35 U.S have been fully considered and are persuasive. Therefore, the rejection has been withdrawn. However, upon further consideration, a new ground(s) of rejection is made in view of the newly added limitations to independent claims 21 and 29. Examiner notes that in light of the new primary reference (see rejection below), claims 34, 35, and 37 are now objected to for containing allowable subject matter.
Claim Rejections - 35 USC § 102
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 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.
Claim(s) 29-33 and 36 is/are rejected under 35 U.S.C. 102(a)(1) as being anticipated by Smith et al. (US 2021/0098306 A1, hereafter Smith).
Regarding claim 29, Smith teaches a method, comprising:
forming a first channel layer (242c, Fig. 3, [0082]) and a second channel layer (252c, Fig. 6, [0087]);
forming a first source/drain epitaxy structure (212c, Fig. 4, [0084]) alongside the first channel layer (242c);
forming a first metal silicide layer (214c, Fig. 35, [0055]) over the first source/drain epitaxy structure (212c);
forming a protective layer (barrier layer or liner, not shown, [0061]) over the first metal silicide layer (214c);
forming a first isolation structure (220c, Fig. 14, [0096]) covering the first source/drain epitaxy structure (214c);
after the first isolation structure (220c) is formed, forming a second source/drain epitaxy structure (224c, Fig.17, [0099]) alongside the second channel layer (252c);
forming a second isolation structure (upper half of pre-metallization dielectric, 210, Figs. 18-19, [0101]) covering the second source/drain epitaxy structure (224c);
forming an opening (274c, [0115], 267c, [0116], 258c, [0116], Fig. 33) extending through the first (220c) and second (210) isolation structures to expose the second source/drain epitaxy structure (224c) and a top surface of the protective layer, wherein the opening has a portion (see annotated Fig. 45) below the second source/drain epitaxy structure (224c), and the portion of the opening vertically overlaps the first source/drain epitaxy structure (212c);
forming a second metal silicide layer (226c, Fig. 14, [0056]) over the second source/drain epitaxy structure (224c); and
forming a contact plug (232e, [0057], 228c, [0057], 218c, [0055]) in the opening.
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Regarding claim 30, Smith teaches the method of claim 29, wherein the protective layer (barrier layer or liner, not shown, [0061]) is made of a conductive material (the barrier layer may comprise Ti, [0061]).
Regarding claim 31, Smith teaches the method of claim 29, wherein the protective layer (barrier layer or liner, not shown, [0061]) and the first metal silicide layer (214c, Fig. 35, [0055]) comprise a same metal element (the first silicide can comprise titanium silicide and the barrier layer can include titanium, meaning both contain titanium [0061]).
Regarding claim 32, Smith teaches the method of claim 29, wherein a material of the first metal silicide layer (214c, Fig. 35, [0055]) is different from a material of the second metal silicide layer (226c, Fig. 14, [0056]) (Smith teaches the first metal silicide to be ruthenium silicide and the second metal silicide is titanium silicide [0062]).
Regarding claim 33, Smith teaches the method of claim 29, wherein a material of the first metal silicide layer (214c, Fig. 35, [0055]) has a higher melting point than a material of the second metal silicide layer (226c, Fig. 14, [0056]) (Smith in [0062] teaches the first metal silicide to be ruthenium silicide, containing ruthenium which is known to have a melting point of 2250 Celsius as evidenced by [0120] of Higashiyama (US 2016/0223958 A1), and the second metal silicide is titanium silicide, containing titanium which is known to have a melting point of 1668 Celsius as evidenced by [0120] of Higashiyama).
Regarding claim 34, Smith teaches the method of claim 29. Smith further teaches forming the opening (274c, [0115], 267c, [0116], 258c, [0116], Fig. 33) comprises performing an etching process (Fig. 33 and [0116]), and the etching process removes a portion of the second source/drain epitaxy structure (224c, Fig.17, [0099]). While not explicitly disclosed, Smith teaches in Fig. 34 and [0117] the etching chemistry to form the opening changes to remove the replacement silicide materials to get to the epitaxy structures. Exposing the epitaxy structures would include etching away a portion of that epitaxy structure, even on a microscopic level. Thus, etching the hole to the second source/drain epitaxy structures as taught by Smith would include etching some of the second source/drain epitaxy structure.
Regarding claim 36, Smith teaches the method of claim 29, wherein a bottom end of the portion (see annotated Fig. 45) of the opening (274c, [0115], 267c, [0116], 258c, [0116], Fig. 33) is below a top surface of the first source/drain epitaxy structure (212c, Fig. 4, [0084]).
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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.
Claim(s) 21-22 and 25-28 is/are rejected under 35 U.S.C. 103 as being unpatentable over Smith in view of Hirano et al. (US 2005/0078546 A1, hereafter Hirano).
Regarding claim 21, Smith teaches a method, comprising:
forming a first channel layer (242c, Fig. 3, [0082])and a second channel layer (252c, Fig. 6, [0087]);
forming a first source/drain epitaxy structure (212c, Fig. 4, [0084]) alongside the first channel layer (242c), wherein the first source/drain epitaxy structure (212c) is a P-type source/drain epitaxy structure [0060];
forming a first metal silicide layer (214c, Fig. 35, [0055]) over the first source/drain epitaxy structure (212c),
forming a metal cap (barrier layer or liner, not shown, [0061]) over the first metal silicide layer (214c),
after the metal cap is formed (barrier or liner), forming a second source/drain epitaxy structure (224c, Fig.17, [0099]) alongside the second channel layer (252c) and vertically above the first source/drain epitaxy structure (212c), wherein the second source/drain epitaxy structure (224c) is an N-type source/drain epitaxy structure [0060]; and
forming a second metal silicide layer (226c, Fig. 14, [0056]) over the second source/drain epitaxy structure (224c), wherein the second metal silicide layer (226c) comprises a different metal silicide than the first metal silicide layer (214c) (Smith teaches the first metal silicide to be ruthenium silicide and the second metal silicide is titanium silicide [0062]).
Smith fails to teach wherein the first metal silicide layer comprises molybdenum silicide; and wherein the metal cap and the first metal silicide layer comprises a same metal element.
However, Hirano shows in Fig. 61 shows a P-type region (191, [0200]) in which a suitable silicide in P-type devices is molybdenum silicide with a barrier metal (similar to a metal cap, 451, [0217]) also can comprise molybdenum [0217]. Thus, it would have been obvious to one having ordinary skill in the art before the effective filing date of the claimed invention to modify the silicide and cap of Smith to comprise molybdenum, as Smith states any suitable silicide and barrier can be used [0061] and Hirano teach molybdenum is suitable for P-type devices [0200/0217].
Regarding claim 22, Smith in view of Hirano teach the method of claim 21, wherein a material of the first metal silicide layer (214c, Fig. 35, [0055]) has a higher melting point than a material of the second metal silicide layer (226c, Fig. 14, [0056]) (Smith in view of Hirano teaches the first metal silicide to be molybdenum silicide ([0200] of Hirano), containing molybdenum which is known to have a melting point of 2610 Celsius as evidenced by [0120] of Higashiyama (US 2016/0223958 A1), and the second metal silicide is titanium silicide, containing titanium which is known to have a melting point of 1668 Celsius as evidenced by [0120] of Higashiyama).
Regarding claim 25, Smith in view of Hirano teach the method of claim 21, further comprising forming a metal plug (232e, [0057], 228c, [0057], 218c, [0055]) interfacing with the metal cap (barrier layer or liner, not shown, [0061]) and the second metal silicide layer (226c, Fig. 14, [0056]).
Regarding claim 26, Smith in view of Hirano teach the method of claim 21, further comprising forming an isolation structure (220c, Fig. 14, [0096]) covering the first source/drain epitaxy structure (212c, Fig. 4, [0084]), wherein the first source/drain epitaxy structure (212c) is separated from the isolation structure through the first metal silicide layer (barrier layer or liner, not shown, [0061]).
Regarding claim 27, Smith in view of Hirano teach the method of claim 26, wherein the second source/drain epitaxy structure (224c, Fig.17, [0099]) interfaces with a top surface of the isolation structure (220c, Fig. 14, [0096]).
Regarding claim 28, Smith in view of Hirano teach the method of claim 21. While Smith does not explicitly teach in a cross-sectional view, a widest width of the first source/drain epitaxy structure (212c, Fig. 4, [0084]) is greater than a widest width of the second source/drain epitaxy structure (224c, Fig.17, [0099]). However, Smith says in [0099] that after the formation of the epitaxy 224c, the epitaxial structure can be etched down to size based on device parameters. Thus, depending on the parameters, the width of the of the first source/drain epitaxy structure is greater than a widest width of the second source/drain epitaxy structure.
Allowable Subject Matter
Claims 16-20 are allowed.
The following is an examiner’s statement of reasons for allowance:
Claims 16-20 are allowed primarily because the prior art of record cannot anticipate or render obvious the following limitations, in combination as recited in independent claim(s) 16: “performing an etching process to the second source/drain epitaxy structures, wherein one of the second source/drain epitaxy structures has a portion having two inclined facets, and the etching process removes the portion of the one of the second source/drain epitaxy structures, resulting a vertical sidewall on a remaining portion of the one of the second source/drain epitaxy structure”.
The closest prior art of record, Smith teaches a method of forming a CFET with a common contact plug but fails to teach “performing an etching process to the second source/drain epitaxy structures, wherein one of the second source/drain epitaxy structures has a portion having two inclined facets, and the etching process removes the portion of the one of the second source/drain epitaxy structures, resulting a vertical sidewall on a remaining portion of the one of the second source/drain epitaxy structures”, nor could Examiner find any reason for this limitation.
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.”
Claims 35 and 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:
Claim 35 is objected primarily because the prior art of record cannot anticipate or render obvious the following limitations, in combination as recited in dependent claim(s) 35: “the first metal silicide layer has a more symmetric cross-sectional profile than the second metal silicide layer in a cross-sectional view” in combination with the limitations of independent claim 29.
The closest prior art of record, Smith teaches a method of forming a CFET with a common contact plug but fails to teach “the first metal silicide layer has a more symmetric cross-sectional profile than the second metal silicide layer in a cross-sectional view”, nor could Examiner find any reason for this limitation.
Claim 37 is objected primarily because the prior art of record cannot anticipate or render obvious the following limitations, in combination as recited in dependent claim(s) 37: “wherein the second source/drain epitaxy structure has a portion having two inclined facets, and forming the opening comprises removing the portion of the second source/drain epitaxy structure, resulting a vertical sidewall on a remaining portion of the second source/drain epitaxy structure” in combination with the limitations of independent claim 29.
The closest prior art of record, Smith teaches a method of forming a CFET with a common contact plug but fails to teach “wherein the second source/drain epitaxy structure has a portion having two inclined facets, and forming the opening comprises removing the portion of the second source/drain epitaxy structure, resulting a vertical sidewall on a remaining portion of the second source/drain epitaxy structure”, nor could Examiner find any reason for this limitation.
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.
Any inquiry concerning this communication or earlier communications from the examiner should be directed to SAMMANTHA K SALAZ whose telephone number is (571)272-2484. The examiner can normally be reached Monday - Friday 8:00am-5:00pm.
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/SAMMANTHA K SALAZ/Examiner, Art Unit 2892
/LEX H MALSAWMA/Primary Examiner, Art Unit 2892
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