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 I drawn to claims 1-17 and 21-23 in the reply filed on 06/22/2026 is acknowledged.
Claims 18-20 are withdrawn from further consideration pursuant to 37 CFR 1.142(b) as being drawn to a nonelected Group II, there being no allowable generic or linking claim. Election was made without traverse in the reply filed on 06/22/2026.
On 08/10/2026 a phone call to the Applicant’s representative Li Yang was initiated by the examiner to clarify what appears to be typographical error in the document Remarks filed on 06/22/2026 on page 6 in line 12 of the document. The document appears to request the examination of claims 1-17 and 21-12. The examiner suspected that this is a typographical error and that what is meant is claims 1-17 and 21-23. Applicant’s representative Li Yang confirmed that this is an error and that the examiner’s interpretations is what was intended.
Information Disclosure Statement
The information disclosure statement (IDS) submitted on 05/07/2024 and 10/24/2025 was filed after the mailing date of the application on 05/07/2024. The submission is in compliance with the provisions of 37 CFR 1.97. Accordingly, the information disclosure statement is being considered by the examiner.
Claim Objections
Claim 15 is objected to because of the following informalities:
Claim 15 contains the limitation: “…wherein the dopant concentration has another peak in a depth lower than where the peak locates” (emphasis added). Suggested possible corrections include changing the language in the claim to be: “… where the peak is located.”.
Appropriate correction is required.
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.
The following is a quotation of 35 U.S.C. 112 (pre-AIA ), second paragraph:
The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the applicant regards as his invention.
Claim 15 recites the limitation " wherein the dopant concentration has another peak in a depth lower than where the peak locates." (emphasis added) in lines 1-2 of the claim. Claim 15 is dependent on claim 13. Claim 13 contains the limitation: “… wherein the dopant concentration has a peak above…”. Claim 15 introduces another reference to another peak: “has another peak…”. Thus there is insufficient antecedent basis for the limitation “… the peak…” in claim 15 leading to a confusion as to which peak is being referenced by this limitation.
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.
Rejection Note: Italicized claim limitations indicate limitations that are not explicitly disclosed in the primary reference, but disclosed in the secondary reference(s).
Claims 1-3, 11-12 and 21 are rejected under 35 U.S.C. 103) as being unpatentable over Chung et al, US 20210328020 A1 (Chung) in view of Wang et al, US 20240079445 A1 (Wang).
Regarding claim 1; Chung teaches a method, comprising:
forming a stack (Chung: Annotated Fig (2B) shared in this OA: 204) over a substrate (202), the stack (204) comprising a plurality of channel layers (208) interleaved by a plurality of sacrificial layers (206);
patterning the stack (204) to form a fin-shape structure (210; [0019]: “… a fin-shaped structure 210 is formed from the stack 204…”), the fin-shape structure (210) comprising a channel region (Channel Region) and a source/drain region (Source/Drain Region);
forming a dummy gate stack (Annotated Figs (4A) and (4B) shared in this OA: 218) over the channel region (Channel Region) of the fin-shape structure (210);
depositing gate spacers (Fig (7A): 224) on sidewalls of the dummy gate stack (218);
recessing the source/drain region (Source/Drain Region) to form a source/drain trench (222, [0024]: “… the fin-shaped structure 210 is recessed to form a source/drain trench 222…”) that exposes sidewalls of the channel layers (208) and the sacrificial layers (206);
partially recessing the sacrificial layers (206) to form a plurality of inner spacer recesses (recesses containing 226);
forming a plurality of inner spacers (Fig (9A): 226) in the inner spacer recesses (recesses containing 226);
forming an epitaxial feature (228, [0027]: “…a first outer epitaxial feature 228 is formed in the source/drain trench 222…”) in the source/drain trench (222);
after the forming of the epitaxial feature (228), removing the dummy gate stack ([0021]: “... In some embodiments, a gate replacement process (or gate-last process) is adopted where the dummy gate stack 218 (shown in FIG. 4A) serves as a placeholder to undergo various processes and is to be removed and replaced by the functional gate structure…”);
releasing the channel layers (208, [0017]: “… the sacrificial layers 206 in channel regions(s) may eventually be removed and serve to define a vertical distance between adjacent channel region(s) for a subsequently-formed multi-gate device and the thickness of each of the sacrificial layers 206 is chosen based on device performance considerations…”, removing the sacrificial layers 206 releases the channel layers 208) in the channel region (region containing layers 208) as a plurality of channel members (208);
forming a gate structure (Fig (11A): 250) wrapping around ([0038]: “… The method 100 may include further operations to form the gate structure 250 to wrap around each of the released channel layers 208…”) each of the channel members (208); and
after the forming of the gate structure (250), performing an ion implantation to increase a dopant concentration of a dopant in the epitaxial feature.
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While Chung teaches the formation of a gate structure (250) and the doping of the epitaxial features, it fails to mention that the doping of the epitaxial structures happens after the formation of the gate structure. Thus, Chung does not teach after the forming of the gate structure, performing an ion implantation to increase a dopant concentration of a dopant in the epitaxial feature.
Wang teaches after the forming of the gate structure (Wang: Fig (1): 12), performing an ion implantation to increase a dopant concentration of a dopant in the epitaxial feature ([0033]: “…and filling the trenches formed with the gate oxide layers with gate conductors to form a plurality of super-junction gates and a plurality of structural gates; [0034] performing ion implantation on a top surface of the epitaxial layer between every two adjacent super-junction gates and between one of the super-junction gates and an adjacent structural gate (if any), after which implanted ions are diffused to form wells”, as can be seen from these two paragraphs of Wang, it appears that the formation of the gate structures precedes the ion implantation step).
Chung and Wang are considered analogous art. Thus, it would have been obvious, prior to the effective filing date of the instant application, to a person of ordinary skill in the art to modify Chung by performing the ion implantation in the epitaxial layers after the formation of the gates as disclosed in Wang to improve the accuracy of the doping process in terms of the location of the formed wells leading to a better performing and more reliable device.
Regarding claim 2; Chung in view of Wang teaches all the limitations of the method of claim 1.
Further, Chung teaches wherein the dopant is an n-type dopant (Chung: [0015]: “… In embodiments where the semiconductor device is p-type, an n-type doping profile (i.e., an n-type well or n-well) may be formed on the substrate 202. In some implementations, the n-type dopant for forming the n-type well may include phosphorus (P) or arsenide (As).”).
Regarding claim 3; Chung in view of Wang teaches all the limitations of the method of claim 2.
Further, Chung teaches wherein the dopant is phosphorus ([0015]: “…the n-type dopant for forming the n-type well may include phosphorus (P) or arsenide (As).”).
Regarding claim 11; Chung teaches a method, comprising:
forming a plurality of channel members (Chung: Fig (2B): 208) disposed over a fin-shape substrate (210; [0019]: “… a fin-shaped structure 210 is formed from the stack 204…”);
forming a plurality of inner spacers (226) interleaving the channel members (208);
forming an epitaxial feature (Fig (9A): 228, [0027]: “…a first outer epitaxial feature 228 is formed in the source/drain trench 222…”) abutting the channel members 208);
forming a gate structure (250) wrapping around ([0038]: “… The method 100 may include further operations to form the gate structure 250 to wrap around each of the released channel layers 208…”) each of the channel members (208); and
after the forming of the gate structure (250), increasing a dopant concentration in the epitaxial feature
While Chung teaches the formation of a gate structure (250) and the doping of the epitaxial features, it fails to mention that the doping of the epitaxial structures happens after the formation of the gate structure. Thus, Chung does not teach after the forming of the gate structure, increasing a dopant concentration in the epitaxial feature.
Wang teaches after the forming of the gate structure (Wang: Fig (1): 12), increasing a dopant concentration in the epitaxial feature ([0033]: “…and filling the trenches formed with the gate oxide layers with gate conductors to form a plurality of super-junction gates and a plurality of structural gates; [0034] performing ion implantation on a top surface of the epitaxial layer between every two adjacent super-junction gates and between one of the super-junction gates and an adjacent structural gate (if any), after which implanted ions are diffused to form wells”, as can be seen from these two paragraphs of Wang, it appears that the formation of the gate structures precedes the ion implantation step).
Chung and Wang are considered analogous art. Thus, it would have been obvious, prior to the effective filing date of the instant application, to a person of ordinary skill in the art to modify Chung by performing the ion implantation in the epitaxial layers after the formation of the gates as disclosed in Wang to improve the accuracy of the doping process in terms of the location of the formed wells leading to a better performing and more reliable device.
Regarding claim 12; Chung in view of Wang teaches all the limitations of the method of claim 11.
Further, Chung teaches wherein the increasing of the dopant concentration includes a phosphorus ion implantation process ([0013]: “… The inner epitaxial feature and the outer epitaxial layer may be formed of different semiconductor layers or of a semiconductor material doped with different dopants….” and [0015]: “… In some implementations, the n-type dopant for forming the n-type well may include phosphorus (P) or arsenide (As). The suitable doping may include ion implantation of dopants and/or diffusion processes.”).
Regarding claim 21; Chung teaches a method, comprising:
forming a stack (Chung: Fig (2B): 204) over a substrate (202), the stack (204) comprising a plurality of channel layers (208) interleaved by a plurality of sacrificial layers (206);
patterning the stack (204) to form a fin-shape structure (210; [0019]: “… a fin-shaped structure 210 is formed from the stack 204…”), the fin-shape structure (210) comprising a channel region (Channel Region) and a source/drain region (Source/Drain Region);
forming a dummy gate stack (Fig (4A): 218) over the channel region (Channel Region) of the fin-shape structure (210);
depositing gate spacers (Fig (7A): 224) on sidewalls of the dummy gate stack (218);
recessing the source/drain region (regions on the sides of the channel region containing layers 208) to form a source/drain trench (222, [0024]: “… the fin-shaped structure 210 is recessed to form a source/drain trench 222…”) that exposes sidewalls of the channel layers (208) and the sacrificial layers (206);
forming a source/drain epitaxial feature (228, [0027]: “…a first outer epitaxial feature 228 is formed in the source/drain trench 222…”) in the source/drain trench (222);
after the forming of the source/drain epitaxial feature (228), removing the dummy gate stack ([0021]: “... In some embodiments, a gate replacement process (or gate-last process) is adopted where the dummy gate stack 218 (shown in FIG. 4A) serves as a placeholder to undergo various processes and is to be removed and replaced by the functional gate structure…”);
releasing the channel layers (208, [0017]: “… the sacrificial layers 206 in channel regions(s) may eventually be removed and serve to define a vertical distance between adjacent channel region(s) for a subsequently-formed multi-gate device and the thickness of each of the sacrificial layers 206 is chosen based on device performance considerations…”, removing the sacrificial layers 206 releases the channel layers 208) in the channel region (Channel Region) as a plurality of channel members (208);
forming a gate structure (Fig (11A): 250) wrapping around at least one of the channel members ([0038]: “… The method 100 may include further operations to form the gate structure 250 to wrap around each of the released channel layers 208…”); and
after the forming of the gate structure (250), performing an ion implantation to increase a dopant concentration of an n-type dopant in the source/drain epitaxial feature.
While Chung teaches the formation of a gate structure (250) and the doping of the epitaxial features, it fails to mention that the doping of the epitaxial structures happens after the formation of the gate structure. Thus, Chung does not teach after the forming of the gate structure, performing an ion implantation to increase a dopant concentration of a dopant in the epitaxial feature.
Wang teaches after the forming of the gate structure (Wang: Fig (1): 12), performing an ion implantation to increase a dopant concentration of a dopant in the epitaxial feature ([0033]: “…and filling the trenches formed with the gate oxide layers with gate conductors to form a plurality of super-junction gates and a plurality of structural gates; [0034] performing ion implantation on a top surface of the epitaxial layer between every two adjacent super-junction gates and between one of the super-junction gates and an adjacent structural gate (if any), after which implanted ions are diffused to form wells”, as can be seen from these two paragraphs of Wang, it appears that the formation of the gate structures precedes the ion implantation step).
Chung and Wang are considered analogous art. Thus, it would have been obvious, prior to the effective filing date of the instant application, to a person of ordinary skill in the art to modify Chung by performing the ion implantation in the epitaxial layers after the formation of the gates as disclosed in Wang to improve the accuracy of the doping process in terms of the location of the formed wells leading to a better performing and more reliable device.
Claims 4-5 are rejected under 35 U.S.C. 103 as being unpatentable over Chung et al, US 20210328020 A1 (Chung) in view of Wang et al, US 20240079445 A1 (Wang) in further view of Lai et al, US 20230040387 A1 (Lai ‘387).
Regarding claim 4; Chung in view of Wang teaches all the limitations of the method of claim 1.
Chung in view of Wang does not teach further comprising: depositing a dielectric layer over the epitaxial feature; etching through the dielectric layer to form a hole exposing a top surface of the epitaxial feature; and prior to the performing of the ion implantation, depositing a liner along sidewalls of the hole.
Lai ‘387 teaches further comprising: depositing a dielectric layer (Lai: Fig (16): 384) over the epitaxial feature (360, 362); etching through the dielectric layer (Fig (17): 384) to form a hole exposing a top surface of the epitaxial feature (360, 362); and prior to the performing of the ion implantation, depositing a liner along sidewalls of the hole ([0047]: “… The operation 518 may form silicide layer(s) (not shown) between contact ring 380 and the first epitaxial rings 360 and between contact ring 380 and the second epitaxial rings 362. The silicide layer(s) may include titanium silicide (TiSi)”).
Chung in view of Wang and Lai ‘387 are considered analogous art. Thus, it would have been obvious, prior to the effective filing date of the instant application filing date, to a person having ordinary skill in the art, to modify Chung in view of Wang by using the dielectric layer and the liner disclosed in Lai ‘387 to improve the separation of the different electrical connections in the device while facilitating easier ways of connecting contacts to the source/drain areas leading to a more reliable device production process.
Regarding claim 5; Chung in view of Wang in further view of Lai ‘387 teaches all the limitations of the method of claim 4.
However, Chung in view of Wang does not teach wherein the liner is a titanium layer.
Lai ‘387 teaches wherein the liner is a titanium layer (Lai ‘387: [0047]: “… The operation 518 may form silicide layer(s) (not shown) between contact ring 380 and the first epitaxial rings 360 and between contact ring 380 and the second epitaxial rings 362. The silicide layer(s) may include titanium silicide (TiSi)”).
Chung in view of Wang and Lai ‘387 are considered analogous art. Thus, it would have been obvious, prior to the effective filing date of the instant application, to one of ordinary skill in the art, to modify Chung in view of Wang by using the titanium layer disclosed in Lai ‘387 to improve the bonding between the epitaxial structures and prevent ion migration from doped areas leading to a more reliable device.
Claim 6 is rejected under 35 U.S.C. 103 as being unpatentable over Chung et al, US 20210328020 A1 (Chung) in view of Wang et al, US 20240079445 A1 (Wang) in further view of Lin et al, US 20210375687 A1 (Lin).
Regarding claim 6; Chung in view of Wang teaches all the limitations of the method of claim 1.
Chung in view of Wang does not teach wherein the ion implantation uses phosphorus dimer.
Lin teaches wherein the ion implantation uses phosphorus dimer (Lin: [0047]: "... In some particular embodiments, the first implantation 26 implants arsenic, and the second implantation 30 implants phosphorous dimer.").
Chung in view of Wang and Lin are considered analogous art. Thus, it would have been obvious, prior to the effective filing date of the instant application, to a person having ordinary skill in the art, to modify Chung in view of Wang by using a phosphorus dimer for impurity implantations as disclosed in Lin to increase the beam efficiency of delivering dopant ions by doubling the number of ions delivered making the doping process more efficient.
Claims 7-10 and 23 are rejected under 35 U.S.C. 103 as being unpatentable over Chung et al, US 20210328020 A1 (Chung) in view of Wang et al, US 20240079445 A1 (Wang) in further view of Nakagawa, US 20230187486 A1 (Nakagawa).
Regarding claim 7; Chung in view of Wang teaches all the limitations of the method of claim 1.
Chung in view of Wang does not teach wherein the dopant concentration has a first peak located above a top surface of a top second one of the channel members.
Nakagawa teaches wherein the dopant concentration has a first peak (Nakagawa: Fig (105): [2099]: “Referring to FIG. 105, the SiC epitaxial layer 422 includes the high concentration region 422a, the low concentration region 422b, and a concentration gradient region 422c interposed between the high concentration region 422a and the low concentration region 422b, in this embodiment”, the high concentration region 422a has a top surface which is higher than the top surface of the channel region 431a) located above a top surface of a top second one of the channel members (431a, [1031]: “The active trench portion 431a is a portion in the active region 406 along a channel region of the MISFET”).
Chung in view of Wang and Nakagawa are considered analogous art. Thus, it would have been obvious, prior to the effective filing date of the instant application, to a person having ordinary skill in the art, to modify Chung in view of Wang by constructing a maximum concentration peak of the dopant material in the epitaxial layer above the top surface of the channel as disclosed in Nakagawa to improve the current control in the channels leading to a better performing device.
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Regarding claim 8; Chung in view of Wang in further view of Nakagawa teaches all the limitations of the method of claim 7.
However, Chung in view of Wang does not teach wherein the dopant concentration has a second peak located between the top surface and a bottom surface of the top second one of the channel members.
Nakagawa teaches wherein the dopant concentration has a second peak (Nakagawa: Fig (105): [2099]: “Referring to FIG. 105, the SiC epitaxial layer 422 includes the high concentration region 422a, the low concentration region 422b, and a concentration gradient region 422c interposed between the high concentration region 422a and the low concentration region 422b, in this embodiment”, the low concentration region 422b is positioned between the top and bottom surfaces of the top channel regions) located between the top surface and a bottom surface of the top second one of the channel members (431a).
Chung in view of Wang and Nakagawa are considered analogous art. Thus, it would have been obvious, prior to the effective filing date of the instant application, to a person having ordinary skill in the art, to modify Chung in view of Wang by constructing a second concentration peak as disclosed in Nakagawa to improve control over the current in the channels and to reduce the possibilities of current leakage in the device leading to a more reliable device.
Regarding claim 9; Chung in view of Wang teaches all the limitations of the method of claim 1.
However, Chung in view of Wang does not teach wherein the dopant concentration in a bottom portion of the epitaxial feature is at least one magnitude lower than in a top portion of the epitaxial feature.
Nakagawa teaches wherein the dopant concentration in a bottom portion (Nakagawa: Fig (105): 422b) of the epitaxial feature (422a, 422b) is at least one magnitude lower than in a top portion (422a) of the epitaxial feature ([1017]: “The n-type impurity concentration of the high concentration region 422a may be not less than 1×10.sup.16 cm.sup.−3 and not more than 1×10.sup.18 cm.sup.−3. The n-type impurity concentration of the low concentration region 422b may be not less than 1×10.sup.15 cm.sup.−3 and not more than 1×10.sup.16 cm.sup.−3”).
Chung in view of Wang and Nakagawa are considered analogous art. Thus, it would have been obvious, prior to the effective filing date of the instant application, to a person having ordinary skill in the art, to modify Chung in view of Wang by constructing the concentration of the bottom portion of the epitaxial structure to be an order of magnitude lower than the concentration of dopants in the top portion of the epitaxial structure as disclosed in Nakagawa to reduce the possibilities of current leakage in the device leading to a more reliable device.
Regarding claim 10; Chung in view of Wang teaches all the limitations of the method of claim 1
However, Chung in view of Wang does not teach wherein the dopant concentration at a same depth of the epitaxial feature is substantially same.
Nakagawa teaches wherein the dopant concentration at a same depth of the epitaxial feature (Nakagawa: Fig (105): 422a, 422b) is substantially same ([2099]: “Referring to FIG. 105, the SiC epitaxial layer 422 includes the high concentration region 422a, the low concentration region 422b, and a concentration gradient region 422c interposed between the high concentration region 422a and the low concentration region 422b, in this embodiment.", this statement indicated that both epitaxial features 422a and 422b have constant dopant concentrations throughout their structures and thus at any similar depths two points on one of the structures will contain the same concentration of dopants as opposed to the gradient concentration feature 422c).
Chung in view of Wang and Nakagawa are considered analogous art. Thus, it would have been obvious, prior to the effective filing date of the instant application, to a person having ordinary skill in the art, to modify Chung in view of Wang by using the constant doping concentration at the same horizontal levels as disclosed in Nakagawa to improve control over the current in the channel regions leading to a better performing device.
Regarding claim 23; Chung in view of Wang teaches all the limitations of the method of claim 21.
However, Chung in view of Wang does not teach wherein the dopant concentration has a first peak located above a top surface of a top second one of the channel members and a second peak located between the top surface and a bottom surface of the top second one of the channel members.
Nakagawa teaches wherein the dopant concentration has a first peak (Nakagawa: Fig (105): [2099]: “Referring to FIG. 105, the SiC epitaxial layer 422 includes the high concentration region 422a, the low concentration region 422b, and a concentration gradient region 422c interposed between the high concentration region 422a and the low concentration region 422b, in this embodiment”, the high concentration region 422a has a top surface which is higher than the top surface of the channel region 431a) located above a top surface of a top second one of the channel members (431a, [1031]: “The active trench portion 431a is a portion in the active region 406 along a channel region of the MISFET”) and a second peak (Nakagawa: Fig (105): [2099]: “Referring to FIG. 105, the SiC epitaxial layer 422 includes the high concentration region 422a, the low concentration region 422b, and a concentration gradient region 422c interposed between the high concentration region 422a and the low concentration region 422b, in this embodiment”, the low concentration region 422b is positioned between the top and bottom surfaces of the top channel regions) located between the top surface and a bottom surface of the top second one of the channel members (431a).
Chung in view of Wang and Nakagawa are considered analogous art. Thus, it would have been obvious, prior to the effective filing date of the instant application, to a person having ordinary skill in the art, to modify Chung in view of Wang by constructing a first and a second concentration peaks as disclosed in Nakagawa to improve control over the current in the channels and to reduce the possibilities of current leakage in the device leading to a more reliable device.
Claim 13 is rejected under 35 U.S.C. 103 as being unpatentable over Chung et al, US 20210328020 A1 (Chung) in view of Wang et al, US 20240079445 A1 (Wang) in further view of Lee et al, US 20230187540 A1 (Lee ‘540).
Regarding claim 13; Chung in view of Wang teaches all the limitations of the method of claim 11.
However, Chung in view of Wang does not teach wherein the dopant concentration has a peak above about 1x1022 atoms/cm3.
Lee ‘540 teaches wherein the dopant concentration has a peak above about 1x1022 atoms/cm3 (Lee ‘540: [0044]: “… In some embodiments, dopant clusters 140 of a dopant material can be embedded in S/D region 124 with a concentration from about 3 × 10.sup.20/cm.sup.3 to about 6 × 10.sup.22/cm.sup.3, from about 1 × 10.sup.21/cm.sup.3 to about 3 × 10.sup.22/cm.sup.3,or from about 1 × 10.sup.21/cm.sup.3to about 1 × 10.sup.22/cm.sup.3”).
Chung in view of Wang and Lee ‘540 are considered analogous art. Thus, it would have been obvious, prior to the effective filing date of the instant application, to a person having ordinary skill in the art, to modify Chung in view of Wang by making the dopant concentration at the ranges disclosed in Lee ‘540 to reduce the resistance of the epitaxial structures and thus lead to a more efficient device.
Claims 14-15 are rejected under 35 U.S.C. 103 as being unpatentable over Chung et al, US 20210328020 A1 (Chung) in view of Wang et al, US 20240079445 A1 (Wang) in further view of Lee et al, US 20230187540 A1 (Lee ‘540) in further view of Nakagawa, US 20230187486 A1 (Nakagawa).
Regarding claim 14; Chung in view of Wang in further view of Lee ‘540 teach all the limitations of the method of claim 13.
However, Chung in view of Wang in further view of Lee ‘540 does not teach wherein the peak is located above a bottom surface of a top second one of the channel members.
Nakagawa teaches wherein the peak (Nakagawa: Fig (105): [2099]: “Referring to FIG. 105, the SiC epitaxial layer 422 includes the high concentration region 422a, the low concentration region 422b, and a concentration gradient region 422c interposed between the high concentration region 422a and the low concentration region 422b, in this embodiment”, the high concentration region 422a has a top surface which is higher than the top surface of the channel region 431a) is located above a bottom surface of a top second one of the channel members (431a, [1031]: “The active trench portion 431a is a portion in the active region 406 along a channel region of the MISFET”).
Chung in view of Wang in further view of Lee ‘540 and Nakagawa are considered analogous art. Thus, it would have been obvious, prior to the effective filing date of the instant application, to a person having ordinary skill in the art, to modify Chung in view of Wang in further view of Lee ‘540 by constructing a maximum concentration peak of the dopant material in the epitaxial layer above the top surface of the channel as disclosed in Nakagawa to improve the current control in the channels leading to a better performing device.
Regarding claim 15; Chung in view of Wang in further view of Lee ‘540 teaches all the limitations of the method of claim 13
However, Chung in view of Wang in further view of Lee ‘540 does not teach wherein the dopant concentration has another peak in a depth lower than where the peak locates.
Nakagawa teaches wherein the dopant concentration has another peak (Nakagawa: Fig (105): [2099]: “Referring to FIG. 105, the SiC epitaxial layer 422 includes the high concentration region 422a, the low concentration region 422b, and a concentration gradient region 422c interposed between the high concentration region 422a and the low concentration region 422b, in this embodiment”, the low concentration region 422b is positioned between the top and bottom surfaces of the top channel regions) in a depth lower than where the peak locates.
Chung in view of Wang in further view of Lee ‘540 and Nakagawa are considered analogous art. Thus, it would have been obvious, prior to the effective filing date of the instant application, to a person having ordinary skill in the art, to modify Chung in view of Wang in further view of Lee ‘540 by constructing another concentration peak as disclosed in Nakagawa to improve control over the current in the channels and to reduce the possibilities of current leakage in the device leading to a more reliable device.
Claim 16 is rejected under 35 U.S.C. 103 as being unpatentable over Chung et al, US 20210328020 A1 (Chung) in view of Wang et al, US 20240079445 A1 (Wang) in further view of Lee et al, US 20230317830 A1 (Lee ‘830)
Regarding claim 16; Chung in view of Wang teaches all the limitations of the method of claim 11.
Further, Chung in view of Wang does not teach wherein prior to the increasing of the dopant concentration, the epitaxial feature is substantially undoped.
Lee ‘830 teaches wherein prior to the increasing of the dopant concentration, the epitaxial feature (Lee ‘830: Fig (8F): 806) is substantially undoped ([0089]: “Then ion implantation is applied to exposed surface of the undoped epitaxial layer 806 in the source/drain space 21 of the semiconductor device structure 1120B with an ion beam 1230 that include dopant ions and a top layer 33 having dopant ions is produced at top surface of the undoped epitaxial layer 806 to dope the top layer 33 of the undoped epitaxial layer 806.”).
Chung in view of Wang and Lee ‘830 are considered analogous art. Thus, it would have been obvious, prior to the effective filing date of the instant application, to a person having ordinary skill in the art, to modify Chung in view of Wang by using undoped epitaxial layers that are later doped to the desired levels to control the doping concentration leading to better control over the current in the channels leading to a more reliable device.
Claim 22 is rejected under 35 U.S.C. 103 as being unpatentable over Chung et al, US 20210328020 A1 (Chung) in view of Wang et al, US 20240079445 A1 (Wang) in further view of Lai et al, US 20230040387 A1 (Lai ‘387) in further view of Yoshino, (2019). Fully Ion Implanted Normally-Off GaN DMOSFETs with ALD-Al2O3 Gate Dielectrics. Materials. 12. 689. 10.3390/ma12050689.
Regarding claim 22; Chung in view of Wang teaches all the limitations of the method of claim 21.
However, Chung in view of Wang does not teach further comprising: prior to the performing of the ion implantation, depositing a dielectric layer over the source/drain feature; etching through the dielectric layer to form a hole exposing a top surface of the source/drain feature; and depositing a liner along sidewalls of the hole, wherein the ion implantation is performed through the hole.
Lai ‘387 teaches further comprising: prior to the performing of the ion implantation, depositing a dielectric layer (Lai ‘387: Fig (16): 384) over the source/drain feature (360, 362); etching through the dielectric layer to form a hole exposing a top surface of the source/drain feature (360, 362); and depositing a liner along sidewalls of the hole ([0047]: “… The operation 518 may form silicide layer(s) (not shown) between contact ring 380 and the first epitaxial rings 360 and between contact ring 380 and the second epitaxial rings 362. The silicide layer(s) may include titanium silicide (TiSi)”), wherein the ion implantation is performed through the hole.
Chung in view of Wang and Lai ‘387 are considered analogous art. Thus, it would have been obvious, prior to the effective filing date of the instant application filing date, to a person having ordinary skill in the art, to modify Chung in view of Wang by using the dielectric layer and the liner disclosed in Lai ‘387 to improve the separation of the different electrical connections in the device while facilitating easier ways of connecting contacts to the source/drain areas leading to a more reliable device production process.
Chung in view of Wang in further view of Lai ‘387 does not teach wherein the ion implantation is performed through the hole.
Yoshino teaches wherein the ion implantation (Yoshino: Fig (5): see the step of implanting Si ions into the structure) is performed through the hole (a hole through a resist layer is shown in Fig (5)).
Chung in view of Wang in further view of Lai ‘387 and Yoshino are considered analogous art. Thus, it would have been obvious, prior to the effective filing date of the instant application, to a person having ordinary skill in the art, to modify Chung in view of Wang in further view of Lai ‘387 by implementing the ion implantation process through a hole as disclosed in Yoshino to improve control over the doping process leading to a more reliable device.
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Allowable Subject Matter
Claims 17 is 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:
Regarding claim 17; Chung alone or in combination with other available art does not teach wherein the epitaxial feature includes a first epitaxial layer abutting the channel members and a second epitaxial layer abutting the inner spacers, wherein the first and second epitaxial layers located at a same depth of the epitaxial feature have a substantially same dopant concentration.
Conclusion
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/M.K./Examiner, Art Unit 2817
/Kretelia Graham/Supervisory Patent Examiner, Art Unit 2817
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