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and the fee set forth in 37 CFR 1.17(e) has been timely paid, the finality of the previous Office action has been withdrawn pursuant to 37 CFR 1.114.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 5/26/2026 has been entered.
Claim Rejections - 35 USC § 103
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 21-23, 25 and 27-29 are rejected under 35 U.S.C. 103 as being unpatentable over Xie et al. (PG Pub. No. US 2021/0265348 A1) in view of Lee et al. (PG Pub. No. US 2023/0120551 A1).
Regarding claim 21, Xie teaches a method comprising:
growing a first epitaxial source/drain region (¶ 0049: 302) adjacent to a first semiconductor nanostructure (¶ 0035, fig. 3: 302 grown adjacent to stack of lower nanostructures 108);
forming a first source/drain contact (¶ 0079: 902/silicide) adjacent to the first epitaxial source/drain region (fig. 9: 902 formed adjacent to 302), the first source/drain contact having a smaller resistance than the first epitaxial source/drain region (¶¶ 0051, 0079: 902 comprises metal material, 302 comprises semiconductor material);
forming an isolation dielectric (¶ 0059: 402) on the first source/drain contact and on the first epitaxial source/drain region (fig. 9: 402 at least indirectly arranged on 902 and 302);
growing a second epitaxial source/drain region (¶ 0060: 502) on the isolation dielectric and adjacent to a second semiconductor nanostructure (¶¶ 0035, fig. 9: 502 formed at least indirectly on 402 and adjacent to upper stack of nanostructures 108), the second semiconductor nanostructure stacked over the first semiconductor nanostructure (fig. 9 among others: upper nanostructures 108 stacks over lower nanostructures 108), the isolation dielectric separating the second epitaxial source/drain region from the first epitaxial source/drain region (fig. 9: 402 separates 502 from 302); and
forming a second source/drain contact (¶ 0080: 904 and/or non-illustrated silicide) adjacent to the second epitaxial source/drain region (fig. 9: 904 formed adjacent to 502), the second source/drain contact having a smaller resistance than the second epitaxial source/drain region (¶¶ 0061, 0079: 904 comprises metal material, 502 comprises semiconductor material), the isolation dielectric separating the second source/drain contact from the first source/drain contact (fig. 5: 402 separates 904 from 902).
Xie does not teach the step of forming an isolation dielectric on the first source/drain contact and on the first epitaxial source/drain region is performed after forming the first source/drain contact.
Lee teaches a method of forming a semiconductor device (figs. 10-12 among others) including forming an isolation dielectric (¶ 0102: 130) on a first source/drain contact and on a first epitaxial source/drain region (fig. 12: 130 formed on a first source/drain contact BC1 and a first epitaxial source/drain region BSD1/BSD2) after forming the first source/drain contact (¶¶ 0100-0102: 130 formed on insulating layer 102, which surrounds BSD1/BSD2; since 130 is formed on 120 and BSD1/2, the broadest reasonable interpretation of “after forming the first source/drain contact” is met).
It would have been obvious to one of ordinary skill in the art at the time the invention was filed to configure the method of Xie with the sequence of Lee, as a means to provide the isolation dielectric fully surrounding the second source/drain region, avoiding formation of undesired features such as voids.
Regarding claim 22, Xie in view of Lee teaches the method of claim 21, wherein the first source/drain contact and the second source/drain contact are formed of the same contact material (Xie, ¶¶ 0055, 0064: in at least one embodiment, 304 and 504 formed of same material).
Regarding claim 23, Xie in view of Lee teaches the method of claim 21, wherein the first source/drain contact and the second source/drain contact are formed of different contact materials (Xie, ¶¶ 0055, 0064: in at least one embodiment, 304 and 504 formed of different materials).
Regarding claim 25, Xie in view of Lee teaches the method of claim 21, wherein the first epitaxial source/drain region and the first source/drain contact are each formed in a recess adjacent to the first semiconductor nanostructure (Xie, ¶ 0079 & fig. 9: 302, 304 formed in recess adjacent to lower nanostructure stack 108), and the first source/drain contact occupies more of the recess than the first epitaxial source/drain region (Xie, fig. 5: 304 occupies more of the recess than 302).
Regarding claim 27, Xie in view of Lee teaches the method of claim 21, wherein forming the first source/drain contact comprises:
depositing a conductive material (Xie, ¶ 0055: in at least one embodiment, 304 formed with conductive dielectric material); and
recessing the conductive material using an etch-back process (Xie, ¶ 0056 & figs. 3-4: recessed below a below spacer 202 by a wet or dry etch-back process).
Regarding claim 28, Xie in view of Lee teaches the method of claim 21, wherein forming the isolation dielectric comprises:
depositing a dielectric material (Xie, ¶ 0055: 304); and
recessing the dielectric material using an isotropic etch (Xie, ¶ 0056: 304 recessed with wet etch, which is inherently isotropic).
Regarding claim 29, Xie in view of Lee teaches the method of claim 21, wherein growing the first epitaxial source/drain region comprises stopping growth of the first epitaxial source/drain region before the first epitaxial source/drain region merges with adjoining epitaxial growth (Xie, fig. 3: 302 growth stopped before vertically or laterally merging).
Claim 24 is rejected under 35 U.S.C. 103 as being unpatentable over Xie in view of Lee as applied to claim 21 above, and further in view of Chu et al. (PG Pub. No. US 2022/0069135 A1).
Regarding claim 24, Xie in view of Lee teaches the method of claim 21, comprising a first epitaxial source/drain region (Xie, 302).
Xie in view of Lee does not teach wherein the first epitaxial source/drain region has a thickness in a range of 1 nm to 5 nm measured in a direction extending between a sidewall of the first semiconductor nanostructure and a sidewall of the first source/drain contact.
Chu teaches a method including forming a first epitaxial source/drain region (¶ 0028: 236, similar to 302 of Xie), wherein the first epitaxial source/drain region has a thickness in a range of 4 nm to 6 nm measured in a direction extending between a sidewall of a first semiconductor nanostructure and a sidewall of a first source/drain contact (¶ 0028, fig. 13A: 236 has a thickness of 4 nm to 6 nm along the x direction, between nanostructures 208 and source/drain contacts 238).
It would have been obvious to one of ordinary skill in the art at the time the invention was filed to configure the first epitaxial source/drain region of Xie in view of Lee with the thickness of Chu, as a means to reduce resistance (Chu, ¶¶ 0004, 0030).
Furthermore, it has been held that 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). In the instant case, the claimed epitaxial source/drain thickness range of 4 nm to 6 nm overlaps the range disclosed by Chu.
Claims 26 is rejected under 35 U.S.C. 103 as being unpatentable over Xie in view of Lee as applied to claim 21 above, and further in view of Ma.
Regarding claim 26, Xie in view of Lee teaches the method of claim 21, comprising growing a first epitaxial source/drain region (Xie, 302).
Xie in view of Lee does not teach the method further comprising:
forming a stop material prior to growing the first epitaxial source/drain region, wherein the first epitaxial source/drain region and the first source/drain contact are each formed on the stop material.
Ma teaches a method including:
forming a stop material (¶¶ 0020, 0039: undoped layer 232) in a recess (fig. 4); and
growing a first epitaxial source/drain region (234) on the stop material (fig. 4).
It would have been obvious to one of ordinary skill in the art at the time the invention was filed to configure the method of Xie in view of Lee with the stop material of Ma, as a means to provide lattice mismatch with source/drain materials (Ma, ¶ 0048), improving performance of the source/drain regions (Ma, ¶ 0012).
Furthermore, the combination of Xie and Ma would implicitly include forming the first source/drain contact of Xie at least indirectly on the stop material of Ma.
Allowable Subject Matter
Claims 15-20 and 30-34 are allowed.
The following is an examiner’s statement of reasons for allowance: The prior art fails to teach or clearly suggest the limitations stating:
“the first source/drain contact and the first epitaxial source/drain region each directly contact a top surface of the stop material” as recited in claim 15, and
“the isolation dielectric directly contacts and extends continually across an upper surface of the first epitaxial source/drain region and a lower surface of the second epitaxial source/drain region” as recited in claim 30.
Xie et al. (US 2021/0265348 A1) teaches a method including forming a first source/drain contact (902) and a first epitaxial source/drain region (302), but does not teach forming a stop material in a nanostructure recess.
Xie et al. (US 2023/0065715 A1, hereinafter referenced as ‘Xi-715’) teaches a method including forming a nanostructure recess (fig. 6) and forming a source/drain contact (1710) and a first epitaxial source/drain region (710) each directly contacting a top surface of a stop material (fig. 17: 1710 and 710 each directly contact a top surface of layer 210). However, Xie-715 fails to teach forming the stop material in the nanostructure recess.
Therefore, neither Xie not X-715, alone or in combination, teach the features of claim 15.
Furthermore, Frougier (US 10,192,867 B1) teaches an isolation dielectric (810) a first source/drain (S1/D1) and a second source/drain (S2/D2), but fails to teach the isolation dielectric directly contacts and extends continually across upper surfaces of the first and second epitaxial source/drain regions.
Frougier et al. (US 2020/0287046 A1) teaches an isolation dielectric (402) directly contacting and extending continually across an upper surface of a first source/drain region (304), but fails to teach the isolation dielectric directly contacting and extending continually across a lower surface of a second source/drain region, as required by claim 30.
Claims 16-20 and 31-34 depend on claims 15 and 30, and are allowed for implicitly including the allowable subject matter above.
In light of these limitations in the claims (see the Applicant’s fig. 17A & ¶ 0067), the previously applied references do not anticipate or obviate the claimed methods as in the context of the claims.
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.”
Response to Arguments
Applicant’s arguments, see pages 7-8, filed 5/26/2026, with respect to the 35 USC § 102 and 35 USC § 103 rejections of claims 21-29 have been fully considered but are moot because the new ground of rejection does not rely on any reference applied in the prior rejection of record for any teaching or matter specifically challenged in the argument.
Conclusion
Any inquiry concerning this communication or earlier communications from the examiner should be directed to BRIAN TURNER whose telephone number is (571)270-5411. The examiner can normally be reached M-F 8am-5pm.
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/BRIAN TURNER/Examiner, Art Unit 2818
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