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 .
Response to Arguments
The previously issued 112b rejection as to claim 25 is withdrawn in view of the amended claims.
The Applicant’s arguments with respect to claim 10 in the reply filed on 09/02/2026 have been carefully considered, and are persuasive. Claims 10-12 are indicated allowable.
Applicant’s arguments with respect to claim(s) 1, and 21 have been considered but are moot in view of new grounds of rejection.
Claim Rejections - 35 U.S.C. § 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 1-6 and 29 are rejected under 35 U.S.C. 103 as being unpatentable over Chu et al. (US 2021/0391421 A1), hereafter “Chu”, in view of Wang et al. (US 2021/0083114 A1), hereafter “Wang”, in view of Wang et al. (US 2020/0168742 A1), hereafter “Wang ‘742”, and further in view of Huang et al. (US 2021/0375857 A1), hereafter “Huang”.
As to claim 1, Chu teaches a semiconductor structure, comprising:
a plurality of nanostructures (⁋ [0010], “nanosheet FETs, nanowire FETs”; ⁋ [0012], 215) surrounded by a gate structure (Fig. 13C, 240’, ⁋ [0036]);
a source/drain (S/D) structure (Fig. 13B, 260, ⁋ [0030]) adjacent to the gate structure;
a first S/D contact structure (Fig. 14B, ⁋ [0041], 275) formed over a first side of the S/D structure;
a second S/D contact structure (Fig. 20B, ⁋⁋ [0028], [0049], 282) formed over a second side of the S/D structure, wherein the second S/D contact structure comprises a conductive layer (⁋ [0049], 282, “via or metal plug”); and
a dielectric layer (⁋ [0011], 230) adjacent to the second S/D contact structure (Fig. 20C).
Chu fails to teach wherein the dielectric layer is doped with germanium (Ge); and an epitaxial sacrificial structure formed adjacent to the gate structure, wherein the epitaxial sacrificial structure is separated from the second S/D contact structure by the dielectric layer, wherein a portion of the second S/D contact structure overlaps with the gate structure.
Wang teaches a semiconductor structure with a dielectric layer (Fig. 7, ⁋ [0022], 222) adjacent to a s/d contact structure (⁋ [0025], 238), wherein the dielectric layer is doped with germanium (⁋ [0031], “In some examples, the dopant particles include elements such as germanium”)
It would have been obvious to one having ordinary skill in the art at the time the invention was made to utilize germanium dopants in an insulator material as taught by Wang to merge portions of the ILD layer with sidewall portions of the S/D contact (⁋ [0029]), since it has been held to be within the general skill of a worker in the art to select a known material on the basis of its suitability for the intended use as a matter of obvious design choice. In re Leshin, 125 USPQ 416.
Chu modified by Wang fails to teach an epitaxial sacrificial structure formed adjacent to the gate structure, wherein the epitaxial sacrificial structure is separated from the second S/D contact structure by the dielectric layer, wherein a portion of the second S/D contact structure overlaps with the gate structure.
Wang ‘742 teaches a similar semiconductor structure with an epitaxial sacrificial structure (⁋ [0033], Figs. 6A-6B, 240) formed adjacent to a gate structure (⁋ [0016], 210).
It would have been obvious to one having ordinary skill in the art at the time the invention was made to apply the teaching of the epitaxial sacrificial structure as taught by Wang ‘742 into the device of Chu and Wang for the benefit of achieving better different oxidation rates and/or different etch selectivity (⁋ [0034]).
The combination of Chu modified by Wang and Wang ‘742 teaches the limitation wherein the epitaxial sacrificial structure of Wang ‘742 (240) is separated from the second S/D contact structure of Chu (282) by Chu’s dielectric layer (230).
Chu modified by Wang and Wang ‘742 fails to teach wherein a portion of the second S/D contact structure overlaps with the gate structure.
Huang teaches a similar device wherein the backside via i.e. second S/D contact structure (360, Fig. 19B, ⁋ [0057]) which overlaps with the gate structure (260, ⁋ [0043]).
It would have been obvious to one of ordinary skill in the art before the effective filing date to obtain the structure as taught by Huang and incorporate it into the device of Chu modified by Wang and Guler as it would have been an obvious design choice involving routine skill in the art.
As to claim 2, Chu in view of Wang, Wang ‘742, and Huang teach wherein the second S/D contact structure comprises a silicide layer (⁋ [0049], 280, Fig. 20B) formed on the S/D structure, and a first liner layer (Fig. 4C, 229/232, ⁋ [0019]) adjacent to the silicide layer (280) (Fig. 20C).
As to claim 3, Chu in view of Wang, Wang ‘742, and Huang teach further comprising: a second liner layer (Fig. 20D, ⁋ [0047], 274) adjacent to the first liner layer (229/232), wherein a top surface of the second liner layer is higher than a top surface of the first liner layer (top of 274 is higher than 229/232 in Fig. 20D).
As to claim 4, Chu in view of Wang, Wang ‘742, and Huang fails to explicitly teach wherein the second liner layer is doped with germanium (Ge).
Wang teaches a semiconductor structure with a dielectric layer (Fig. 7, ⁋ [0022], 222) adjacent to a s/d contact structure (⁋ [0025], 238), wherein the dielectric layer is doped with germanium (⁋ [0031], “In some examples, the dopant particles include elements such as germanium”).
It would have been obvious to one having ordinary skill in the art at the time the invention was made to utilize germanium dopants in an insulator material as taught by Wang to merge portions of second liner layer with sidewalls of adjacent portions (⁋ [0029]), since it has been held to be within the general skill of a worker in the art to select a known material on the basis of its suitability for the intended use as a matter of obvious design choice. In re Leshin, 125 USPQ 416.
As to claim 5, Chu in view of Wang, Wang ‘742, and Huang teach further comprising: a filling layer (⁋ [0047], 276, Fig. 20B) formed over the second liner layer (274).
Chu in view of Wang fail to teach explicitly teach wherein the filling layer is doped with germanium (Ge).
Wang teaches a semiconductor structure with a dielectric layer (Fig. 7, ⁋ [0022], 222) adjacent to a s/d contact structure (⁋ [0025], 238), wherein the dielectric layer is doped with germanium (⁋ [0031], “In some examples, the dopant particles include elements such as germanium”).
It would have been obvious to one having ordinary skill in the art at the time the invention was made to utilize germanium dopants in a dielectric material as taught by Wang to merge portions of the filling layer with adjacent sidewall portions (⁋ [0029]), since it has been held to be within the general skill of a worker in the art to select a known material on the basis of its suitability for the intended use as a matter of obvious design choice. In re Leshin, 125 USPQ 416.
As to claim 6, Chu in view of Wang, Wang ‘742, and Huang teach wherein the filling layer is further doped with fluorine (F) (⁋ [0047], “fluoride-doped silica glass”) or carbon (C) or carbon (C).
As to claim 29, Chu in view of Wang, Wang ‘742, and Huang teach the semiconductor structure as claimed in claim 1, but fail to teach wherein the second S/D contact structure comprises a T-shaped like structure.
On the other hand, shape, size, and dimension differences are considered obvious design choices and are not patentable unless unobvious or unexpected results are obtained from these changes. It appears that these changes produce no functional differences and therefore would have been obvious. Note In re Dailey, 357 F.2d 669, 149 USPQ 47 (CCPA 1966).
Claim 28 is rejected under 35 U.S.C. 103 as being unpatentable over Chu in view of Wang, Wang ‘742, Huang and further in view of Chu et al. (US 2021/0376093 A1), hereafter “Chu ‘093”.
As to claim 28, Chu in view of Wang, Wang ‘742, and Huang fail to teach further comprising: a filling layer between the second S/D contact structure and the epitaxial sacrificial structure.
Chu ‘093 teaches a similar device with a filling layer (⁋ [0037], Fig. 15A, 270) that is located over the drain features (⁋ [0029], 246D).
It would have been obvious to one of ordinary skill in the art before the effective filing date to apply the teaching of the filling layer as taught by Chu into the device of Chu, Wang, Wang ‘742, and Huang to enable self-alignment of backside source contact openings and backside source contacts (⁋ [0037]).
As a result of the combination, the remaining limitation of the filling layer taught by Chu ‘093 being located between the second S/D contact structure of Chu and the epitaxial sacrificial structure of Wang ‘742 is taught.
Claims 7-9 are rejected under 35 U.S.C. 103 as being unpatentable over Chu in view of Wang, Wang ‘742, and further in view of Huang.
As to claim 7, Chu in view of Wang and Wang ‘742 fail to teach further comprising: an isolation layer below the epitaxial sacrificial structure.
Huang teaches a similar semiconductor structure with an isolation layer (Fig. 14B, ⁋ [0035], 230) located below a sacrificial epitaxial plug i.e. structure (220).
It would have been obvious to one having ordinary skill in the art at the time the invention was made to apply the teaching of the isolation layer as taught by Huang into the device of Chu, Wang and Wang ‘742 because the isolation layers are benefit for reducing current leakage from top epitaxial structures to the substrate (⁋ [0035]).
As to claim 8, Chu in view of Wang, Wang ‘742 and Huang teach the semiconductor structure as claimed in claim 7, Chu teaches further comprising: an inner spacer (⁋ [0025], 255, Fig. 6B) formed adjacent to the nanostructures, wherein the inner spacer of Chu is in direct contact with Huang’s isolation layer (230) (see Huang’s Fig. 14B for the location of 230).
As to claim 9, Chu in view of Wang, Wang ‘742 and Huang teach the semiconductor structure as claimed in 7, Wang ‘742 further teaches wherein the epitaxial sacrificial structure is doped with fluorine (F) or carbon (C) (⁋ [0033]).
Claims 21, 23-24, and 26-27 are rejected under 35 U.S.C. 103 as being unpatentable over Chu in view of Wang, in view of Guler et al. (US 2026/0143748 A1), hereafter “Guler”, and further in view of Huang.
As to claim 21, Chu teaches a semiconductor structure, comprising:
a plurality of nanostructures (⁋ [0010], “nanosheet FETs, nanowire FETs”; ⁋ [0012], 215) surrounded by a gate structure (Fig. 13C, 240’, ⁋ [0036]);
a source/drain (S/D) structure (Fig. 13B, 260, ⁋ [0030]) adjacent to the gate structure;
a first S/D contact structure (⁋ [0041], 275) formed over a first side of the S/D structure;
a second S/D contact structure (Fig. 20B, ⁋⁋ [0028], [0049], 282+280) formed over a second side of the S/D structure, wherein the second S/D contact structure has a top portion and a bottom portion, wherein the top portion is wider than the bottom portion (Fig. 20C shows 282 with a top and bottom portion, and the top portion is wider), wherein the second S/D contact structure comprises a conductive layer (⁋ [0049], 282, “via or metal plug”),
a dielectric layer (⁋ [0011], 230) adjacent to the second S/D contact structure; and
a filling layer (⁋ [0047], 276, Fig. 20B) adjacent to the second S/D contact structure (282+280) and below the dielectric layer (230) (Fig. 20E).
Chu fails to teach wherein the conductive layer is doped with germanium (Ge); wherein the dielectric layer is doped with germanium (Ge), and wherein the filling layer is doped with germanium (Ge), wherein a bottommost surface of the second S/D contact structure is lower than a topmost surface of the gate structure.
Wang teaches a semiconductor structure with a dielectric layer (Fig. 7, ⁋ [0022], 222) adjacent to a s/d contact structure (⁋ [0025], 238), wherein the dielectric layer is doped with germanium (⁋ [0031], “In some examples, the dopant particles include elements such as germanium”).
It would have been obvious to one having ordinary skill in the art at the time the invention was made to utilize germanium dopants in a dielectric material as taught by Wang to merge portions of the first liner layer and filling layer with sidewall portions of the S/D contact (⁋ [0029]), since it has been held to be within the general skill of a worker in the art to select a known material on the basis of its suitability for the intended use as a matter of obvious design choice. In re Leshin, 125 USPQ 416.
Chu in view of Wang fail to teach wherein the conductive layer is doped with germanium (Ge), and wherein a bottommost surface of the second S/D contact structure is lower than a topmost surface of the gate structure.
Guler teaches a semiconductor device in a similar field of endeavor and teaches a conductive later (⁋ [0112], 420) doped with Ge (e.g. Ge).
It would have been obvious to one of ordinary skill in the art before the effective filing date to apply the teaching of a doped conductive layer as taught by Guler into the device of Chu and Wang to enable robust contacts (⁋ [0112]).
Chu in view of Wang and Guler fails to disclose wherein a bottommost surface of the second S/D contact structure is lower than a topmost surface of the gate structure.
Huang teaches a similar device wherein the backside via i.e. second S/D contact structure (360, Fig. 19B, ⁋ [0057]) has a bottommost surface lower than a topmost surface of the gate structure (260, ⁋ [0043]).
It would have been obvious to one of ordinary skill in the art before the effective filing date to obtain the structure as taught by Huang and incorporate it into the device of Chu modified by Wang and Guler as it would have been an obvious design choice involving routine skill in the art.
As to claim 23, Chu in view of Wang, Guler and Huang teach a filling layer (see claim 21) but fail to teach wherein the filling layer has a step-like structure.
On the other hand, shape, size, and dimension differences are considered obvious design choices and are not patentable unless unobvious or unexpected results are obtained from these changes. It appears that these changes produce no functional differences and therefore would have been obvious. Note In re Dailey, 357 F.2d 669, 149 USPQ 47 (CCPA 1966).
As to claim 24, Chu in view of Wang, Guler and Huang teach wherein the filling layer is further doped with fluorine (F) (⁋ [0047], “fluoride-doped silica glass”) or carbon (C).
As to claim 26, Chu in view of Wang, Guler and Huang teach further comprising: a liner layer (Fig. 20D, ⁋ [0047], 274) between the second S/D contact structure (280+282) and the filling layer (276).
Chu in view of Wang, Guler and Huang fail to explicitly teach wherein the liner layer is doped with germanium (Ge).
Wang teaches a semiconductor structure with a dielectric layer (Fig. 7, ⁋ [0022], 222) adjacent to a s/d contact structure (⁋ [0025], 238), wherein the dielectric layer is doped with germanium (⁋ [0031], “In some examples, the dopant particles include elements such as germanium”). Examiner notes that the first liner layer of Chu (274) is described as a dielectric liner (⁋ [0047]).
It would have been obvious to one having ordinary skill in the art at the time the invention was made to utilize germanium dopants in a dielectric material as taught by Wang to merge portions of the first liner layer with sidewall portions of the S/D contact (⁋ [0029]), since it has been held to be within the general skill of a worker in the art to select a known material on the basis of its suitability for the intended use as a matter of obvious design choice. In re Leshin, 125 USPQ 416.
As to claim 27, Chu in view of Wang, Guler and Huang teach further comprising: an inner spacer (⁋ [0025], 255, Fig. 6B) adjacent to the nanostructures; and a liner layer (Fig. 20B, ⁋ [0047], 274) between the inner spacer and the second S/D contact structure.
Chu in view of Wang, Guler and Huang fail to explicitly teach wherein the liner layer is doped with germanium (Ge).
Wang, however, does teach a semiconductor structure with a dielectric layer (Fig. 7, ⁋ [0022], 222) adjacent to a s/d contact structure (⁋ [0025], 238), wherein the dielectric layer is doped with germanium (⁋ [0031], “In some examples, the dopant particles include elements such as germanium”). Examiner notes that the first liner layer of Chu (274) is described as a dielectric liner (⁋ [0047]).
It would have been obvious to one having ordinary skill in the art at the time the invention was made to utilize germanium dopants in a dielectric material as taught by Wang to merge portions of the first liner layer with sidewall portions of the S/D contact (⁋ [0029]), since it has been held to be within the general skill of a worker in the art to select a known material on the basis of its suitability for the intended use as a matter of obvious design choice. In re Leshin, 125 USPQ 416.
Allowable Subject Matter
Claims 10-12 are indicated allowed.
The following is a statement of reasons for the indication of allowable subject matter:
As to claim 10, Chu modified by Wang and Huang are the closest prior arts and teach the device of claim 10 (see for example office action mailed 06/05/2026), however, fail to disclose the isolation layer electrically isolating the epitaxial sacrificial structure from the S/D structure.
Conclusion
Applicant's amendment necessitated the new ground(s) of rejection presented in this Office action. Accordingly, THIS ACTION IS MADE FINAL. See MPEP § 706.07(a). 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 CARNELL HUNTER whose telephone number is (571)270-1796. The examiner can normally be reached Monday - Friday 7:30 am - 4:30pm.
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/CARNELL HUNTER III/ Examiner, Art Unit 2893
/SUE A PURVIS/Supervisory Patent Examiner, Art Unit 2893
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