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 Election/Restrictions
Applicant’s election without traverse of Group I, Species I, claims 1-9 in the reply filed on 12/31/2025 is acknowledged.
Group I, Species II, claim 10-15 and Group II, claims 16-20 are canceled. Claims 21-31 are new.
Information Disclosure Statement
The information disclosure statement (IDS) filed on 08/22/2023 is in compliance with the provisions of 37 CFR 1.97. Accordingly, the IDSs are considered by the examiner.
Claim Objections
Claim 28 is objected to because of the following informalities:
In claim 28, line 4, “the fin structure” should read --the fin-shape structure--, lines 11, 13, “the second-type source/drain feature” should read --the second[[-]]type epitaxial feature--, and lines 12, 15, “the first-type source/drain feature” should read --the first[[-]]type epitaxial feature-- (emphasis added).
Appropriate correction is required.
Specification
The disclosure is objected to because of the following informalities:
Paragraph [0017] uses reference numerals 204 and 206 inconsistently when describing the inner and outer layers of the dielectric features, resulting in ambiguity.
In [0044], lines 9-10, “the surface of the surface of the n-type source/drain features” should read --the surface of the n-type source/drain features-- (emphasis added).
Appropriate correction is required.
Drawings
Figures 11 and 13 are objected to because the reference numeral 280 in Figs. 11 and 13 are inconsistent/unclear with respect to the location and extent of the silicide layer. In Fig. 11, the region indicated by reference numeral 280 appears to extend along the side of the source/drain region 220P, suggesting that the silicide layer surrounds or encases the source/drain region, whereas other figures depict the silicide layer as being located at the bottom portion of the contact opening.
Figure 15 is objected to because the reference numeral 280 in Fig. 15 is unclear and improperly indicated. Specifically, the leader line associated with reference character 280 does not clearly point to the silicide layer, and appears to be connected to an ambiguous region adjacent to the source/drain region.
Corrected drawing sheets in compliance with 37 CFR 1.121(d) are required in reply to the Office action to avoid abandonment of the application. Any amended replacement drawing sheet should include all of the figures appearing on the immediate prior version of the sheet, even if only one figure is being amended. The figure or figure number of an amended drawing should not be labeled as “amended.” If a drawing figure is to be canceled, the appropriate figure must be removed from the replacement sheet, and where necessary, the remaining figures must be renumbered and appropriate changes made to the brief description of the several views of the drawings for consistency. Additional replacement sheets may be necessary to show the renumbering of the remaining figures. Each drawing sheet submitted after the filing date of an application must be labeled in the top margin as either “Replacement Sheet” or “New Sheet” pursuant to 37 CFR 1.121(d). If the changes are not accepted by the examiner, the applicant will be notified and informed of any required corrective action in the next Office action. The objection to the drawings will not be held in abeyance.
Claim Rejections - 35 USC § 112
The following is a quotation of the first paragraph of 35 U.S.C. 112(a):
(a) IN GENERAL.—The specification shall contain a written description of the invention, and of the manner and process of making and using it, in such full, clear, concise, and exact terms as to enable any person skilled in the art to which it pertains, or with which it is most nearly connected, to make and use the same, and shall set forth the best mode contemplated by the inventor or joint inventor of carrying out the invention.
The following is a quotation of the first paragraph of pre-AIA 35 U.S.C. 112:
The specification shall contain a written description of the invention, and of the manner and process of making and using it, in such full, clear, concise, and exact terms as to enable any person skilled in the art to which it pertains, or with which it is most nearly connected, to make and use the same, and shall set forth the best mode contemplated by the inventor of carrying out his invention.
Claims 1-9 are rejected under 35 U.S.C. 112(a) or 35 U.S.C. 112 (pre-AIA ), first paragraph, as failing to comply with the enablement requirement. The claims contain subject matter which was not described in the specification in such a way as to enable one skilled in the art to which it pertains, or with which it is most nearly connected, to make and/or use the invention.
Claim 1 recites the limitation “a contact structure comprising: a top portion extending through the second dielectric layer and the second CESL and contacting the second type epitaxial feature by way of a first metal silicide layer and a dipole layer, and a bottom portion disposed below the top portion, the bottom portion extending through the second type epitaxial feature, the first dielectric layer, and the first CESL and contacting the first type epitaxial feature by way of the first metal silicide layer, the dipole layer and a second metal silicide layer” in lines 12-19. However, the specification describes forming a first silicide layer 280 selectively on the p-type source/drain feature, followed by a global deposition of a second silicide layer 284 (see, paragraphs [0030]-[0031], [0035], and [0036]). The specification further explain that the completed contact structure interfaces the n-type source/drain feature by way of the second silicide layer 284 and the n-type dipole layer 282, and interfaces the p-type source/drain features by way of the second silicide layer 284, the n-type dipole layer 282, and the first silicide layer 280 (see, paragraphs [0038] and FIG. 15).
In view of the foregoing, the specification does not reasonably convey to one of ordinary skill in the art that the inventors had possession of a contact structure in which the top portion contacts the second type epitaxial feature “by way of a first metal silicide layer and a dipole layer” while excluding the second metal silicide layer, as recited in claim 1.
Claim 2 recites the limitation “wherein the first metal silicide layer comprises Ti” in lines 1-2. However, the specification describes embodiments in which the first silicide layer 280 selectively deposited on the p-type source/drain feature includes Mo, Ru, Ni, or Co (see, paragraph [0032]). In contrast, the specification associates Ti with the second silicide layer 284 that is globally deposited over the workpiece (see, paragraph [0036]).
In view of the foregoing, the specification does not reasonably convey to one of ordinary skill in the art that the inventors had possession of a semiconductor structure in which the first metal silicide layer comprises Ti, as required by claim 2.
Claim 3 recites the limitation “the second metal silicide layer comprises Mo, Ru, Ni, or Co” in lines 1-2. However, the specification describes embodiments in which the second silicide layer 284 globally deposited over the workpiece includes Ti (see, paragraph [0036]), while Mo, Ru, Ni, or Co are disclosed as materials for the first silicide layer 280 selectively deposited on the p-type source/drain feature (see, paragraph [0032]).
In view of the foregoing, the specification does not reasonably convey to one of ordinary skill in the art that the inventors had possession of a semiconductor structure in which the second metal silicide layer comprises Mo, Ru, Ni, or Co, as required by claim 3.
Claims 4-9 are rejected for being dependent on claim 1.
Appropriate correction is required.
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 (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 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.
Claims 1-9 and 21-31 are rejected under 35 U.S.C. 103 as being unpatentable over Liao et al. (US 2021/0366907; hereinafter ‘Liao’) in view of Wang et al. (US 2022/0037500; hereinafter ‘Wang’) and Fung (US 2017/0345933).
Regarding claim 1, Liao teaches a semiconductor structure (200, Figs. 17A and 17B, [0042]) comprising:
a fin structure (209, Fig. 3, [0022]) arising from a substrate (202);
an isolation feature (214, Fig. 4, [0023]) surrounding the fin structure (209);
a first type epitaxial feature (244S and 244D, Figs. 15A and 15B, [0038]) disposed over the fin structure (209);
a first contact etching stop layer (CESL) (246, Figs. 15A and 15B, [0038]) disposed on the first type epitaxial feature (244S and 244D) and the isolation feature (214);
a first dielectric layer (248, Figs. 15A and 15B, [0038]) disposed over the first CESL (246);
a second type epitaxial feature (228S and 228D, Figs. 11A and 11B, [0031]) disposed on the first dielectric layer (248);
a second CESL (230, Figs. 12A and 12B, [0032]) disposed on the first dielectric layer (248) and the second type epitaxial feature (228S and 228D);
a second dielectric layer (232, Figs. 12A and 12B, [0032]) disposed over the second CESL (230); and
a contact structure (260 and 234, Figs. 16A and 16B, [0039]) comprising:
a top portion (234) extending through the second dielectric layer (248) and the second CESL (230) and contacting the second type epitaxial feature (228S and 228D), and
a bottom portion (260) disposed below the top portion (234), the bottom portion (260) extending through the second type epitaxial feature (228S and 228D), the first dielectric layer (248), and the first CESL (246) and contacting the first type epitaxial feature (244S and 244D).
Liao does not teach the semiconductor structure, comprising: the contact structure comprising: a first metal silicide layer and a dipole layer.
Wang teaches a semiconductor structure (100, FIGS. 1B and 1C, [0020]) comprising: the contact structure (120, [0023]) comprising: a first metal silicide layer (132, [0021, 0026, 0065]) and a dipole layer (144).
As taught by Wang, one of ordinary skill in the art would utilize and modify the above teaching into Mevellec to obtain and achieve the semiconductor structure, comprising: the contact structure comprising: a first metal silicide layer and a dipole layer as claimed, because it reduces contact resistance by lowering the Schottky barrier height at the S/D interface, thereby directly modulating the metal-semiconductor energy barrier [0018, 0030].
Thus, it would have been obvious to one of ordinary skill in the art before the effective filling date of the claimed invention to employ the teaching as taught by Wang in combination with Liao due to above reason.
Liao in view of Wang does not teach the semiconductor structure, comprising: the contact structure further comprising: a second metal silicide layer, and wherein the first metal silicide layer and the second metal silicide layer have different metal compositions.
Fung teaches a semiconductor structure (300, FIGS. 10A and 10B, [0035]) comprising: the contact structure (802 and 1002) further comprising: a second metal silicide layer (802 includes a plurality of metal layer, [0032]), and wherein the first metal silicide layer (the first layer of 802) and the second metal silicide layer (the second layer of 802) have different metal compositions (802 includes a plurality of metal layer of different materials).
As taught by Fung, one of ordinary skill in the art would utilize and modify the above teaching into Liao in view of Wang to obtain and achieve the semiconductor structure, comprising: the contact structure further comprising: a second metal silicide layer, and wherein the first metal silicide layer and the second metal silicide layer have different metal compositions as claimed, because different silicide materials exhibit different electrical and thermal characteristics, and incorporating multiple silicide materials within a single contact structure allows optimization of source/drain contact performance [0020, 0032].
Thus, it would have been obvious to one of ordinary skill in the art before the effective filling date of the claimed invention to employ the teaching as taught by Fung in combination with Liao in view of Wang due to above reason.
Regarding claim 2, Liao in view of Wang and Fung teaches the semiconductor structure of claim 1, Liao in view of Wang does not teach the semiconductor structure wherein the first metal silicide layer comprises Ti.
Fung teaches the semiconductor structure wherein the first metal silicide layer comprises Ti (802 includes TiSi, [0032]).
It would have been obvious to one of ordinary skill in the art before the effective filling date of the claimed invention to employ and modify the teachings of Fung to obtain and achieve the semiconductor structure wherein the first metal silicide layer comprises Ti as claimed, because Ti is a well-known material and widely used as a silicide layer in the art. Further, 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 used a matter of obvious design choice. In re Leshin, 277 F.2d 197, 125 USPQ 416 (CCPA 1960).
Regarding claim 3, Liao in view of Wang and Fung teaches the semiconductor structure of claim 2, Liao in view of Wang does not teach the semiconductor structure wherein the second metal silicide layer comprises Mo, Ru, Ni, or Co.
Fung teaches the semiconductor structure wherein the second metal silicide layer comprises Mo, Ru, Ni, or Co (802 includes NiSi, [0032]).
It would have been obvious to one of ordinary skill in the art before the effective filling date of the claimed invention to employ and modify the teachings of Fung to obtain and achieve the semiconductor structure wherein the second metal silicide layer comprises Mo, Ru, Ni, or Co as claimed, because Ni is a well-known material and widely used as a silicide layer in the art. Further, 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 used a matter of obvious design choice. In re Leshin, 277 F.2d 197, 125 USPQ 416 (CCPA 1960).
Regarding claim 4, Liao in view of Wang and Fung teaches the semiconductor structure of claim 3, Liao in view of Fung does not teach the semiconductor structure, wherein the dipole layer comprises Zr, Hf, Sb, Ce, Sc, Y, Yb, or Er.
Wang teaches the semiconductor structure wherein the dipole layer comprises Zr, Hf, Sb, Ce, Sc, Y, Yb, or Er (144 includes Zr, Hf, Ce, Sc, Y, Yb, or Er, [0029]).
It would have been obvious to one of ordinary skill in the art before the effective filling date of the claimed invention to employ and modify the teachings of Wang to obtain and achieve the semiconductor structure wherein the dipole layer comprises Zr, Hf, Sb, Ce, Sc, Y, Yb, or Er as claimed, because Zr, Hf, Ce, Sc, Y, Yb, or Er are well-known materials and widely used as a silicide layer in the art. Further, 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 used a matter of obvious design choice. In re Leshin, 277 F.2d 197, 125 USPQ 416 (CCPA 1960).
Regarding claim 5, Liao in view of Wang and Fung teaches the semiconductor structure of claim 1, wherein the fin structure (Liao: 209, Fig. 17B) extends lengthwise along a first direction (z-direction),
wherein the top portion of the contact structure (234) comprises a first width (a width of 234; hereinafter ‘W234’) along a second direction (x-direction) perpendicular to the first direction (z-direction),
wherein the bottom portion of the contact structure (260 comprises a second width (a width of 260; hereinafter ‘W260’) along the second direction (x-direction),
wherein the first width (W234) is greater than the second width (W260).
Regarding claim 6, Liao in view of Wang and Fung teaches the semiconductor structure of claim 1, Liao in view of Wang and Fung does not explicitly teach the semiconductor structure wherein the second metal silicide layer comprises a thickness between about 3 nm and about 6.5 nm.
Wang, however, provides a metal silicide layer (132, FIGS. 1F and 1G) having a thickness ranging from about 2 nm to about 6 nm [0037]. The disclosure is not limited to a particular metal composition or silicide position, but rather defines a thickness range applicable to metal silicide layers formed in semiconductor contact structures.
It would have been obvious to one of ordinary skill in the art before the effective filling date of the claimed invention to employ and modify the teachings of Wang to obtain and achieve the semiconductor structure wherein the second metal silicide layer comprises a thickness between about 3 nm and about 6.5 nm as claimed, because it has been held that where the criticality of the claimed range is not shown and the general conditions of a claim are disclosed in the prior art, discovering the optimum or workable ranges involves only routine skill in the art. MPEP §2144.05.
Regarding claim 7, Liao in view of Wang and Fung teaches the semiconductor structure of claim 1, wherein sidewalls of the contact structure (sidewalls of 260) are spaced apart from the first CESL (246), the first dielectric layer (248), the second type epitaxial feature (228S and 228D), the second CESL (230), and the second dielectric layer (232) by a liner (a linear, [0040]).
Liao in view of Fung does not teach the semiconductor structure wherein sidewalls of the contact structure are spaced by a dielectric liner.
Wang teaches the semiconductor structure wherein sidewalls of the contact structure (142, Figs. 1D and 1F, [0055]) are spaced by a dielectric liner (142 includes SiN).
It would have been obvious to one of ordinary skill in the art before the effective filling date of the claimed invention to employ and modify the teachings of Wang to obtain and the semiconductor structure wherein sidewalls of the contact structure are spaced by a dielectric liner as claimed, because SiN is a well-known material and widely used as a dielectric liner in the art. Further, 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 used a matter of obvious design choice. In re Leshin, 277 F.2d 197, 125 USPQ 416 (CCPA 1960).
Regarding claim 8, Liao in view of Wang and Fung teaches the semiconductor structure of claim 7, Liao in view of Fung does not teach the semiconductor structure wherein the dielectric liner comprises silicon nitride.
Wang teaches the semiconductor structure wherein the dielectric liner comprises silicon nitride (142 includes SiN, Figs. 1D and 1F, [0055]).
It would have been obvious to one of ordinary skill in the art before the effective filling date of the claimed invention to employ and modify the teachings of Wang to obtain and the semiconductor structure wherein the dielectric liner comprises silicon nitride as claimed, because SiN is a well-known material and widely used as a dielectric liner in the art. Further, 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 used a matter of obvious design choice. In re Leshin, 277 F.2d 197, 125 USPQ 416 (CCPA 1960).
Regarding claim 9, Liao in view of Wang and Fung teaches the semiconductor structure of claim 1, wherein the first type epitaxial feature (Liao: 244S and 244D, Figs. 17A and 17B) and the second type epitaxial feature (228S and 228D) are disposed between two dielectric fins (218, [0025]).
Regarding claim 21, Liao teaches a semiconductor structure (200, Figs. 17A and 17B, [0042]) comprising:
a base fin portion (209, Fig. 3, [0022]) extending from a substrate (202);
a p-type source/drain feature (228S and 228D are p-type source/drain, Figs. 11A and 11B, [0031]) over the base fin portion (209);
an n-type source/drain feature (244S and 244D, Figs. 15A and 15B, [0031, 0038]) over the p-type source/drain feature (228S and 228D); and
a contact structure (260 and 234, Figs. 16A and 16B, [0039]) extending through the n-type source/drain feature (244S and 244D) and terminating in the p-type source/drain feature (228S and 228D),
wherein the contact structure (260 and 234) interfaces the n-type source/drain feature (244S and 244D).
Liao does not teach the semiconductor structure wherein the contact structure interfaces the n-type source/drain feature by way of a dipole layer and a first metal silicide layer, wherein the contact structure interfaces the p-type source/drain feature by way of a second metal silicide layer, the dipole layer, and the first metal silicide layer.
Wang teaches a semiconductor structure (100, FIGS. 1B and 1C, [0020])
wherein the contact structure (120, [0023]) interfaces the n-type source/drain feature (110 is a n-type, [0021, 0026, 0065]) by way of a dipole layer (144, [0026]) and a first metal silicide layer (132),
wherein the contact structure (120, [0023]) interfaces the p-type source/drain feature (110 is a p-type) by way of the dipole layer (144), and the first metal silicide layer (132).
As taught by Wang, one of ordinary skill in the art would utilize and modify the above teaching into Mevellec to obtain and achieve the semiconductor structure wherein the contact structure interfaces the n-type source/drain feature by way of a dipole layer and a first metal silicide layer, wherein the contact structure interfaces the p-type source/drain feature by way of the dipole layer, and the first metal silicide layer as claimed, because it reduces contact resistance by lowering the Schottky barrier height at the S/D interface, thereby directly modulating the metal-semiconductor energy barrier [0018, 0030].
Thus, it would have been obvious to one of ordinary skill in the art before the effective filling date of the claimed invention to employ the teaching as taught by Wang in combination with Liao due to above reason.
Liao in view of Wang does not teach the semiconductor structure comprising: the contact structure further comprising: a second metal silicide layer, and wherein a composition of the first metal silicide layer is different from a composition of the second metal silicide layer.
Fung teaches a semiconductor structure (300, FIGS. 10A and 10B, [0035]) comprising: the contact structure (802 and 1002) further comprising: a second metal silicide layer (802 includes a plurality of metal layer, [0032]), and wherein a composition of the first metal silicide layer is different from a composition of the second metal silicide layer (802 includes a plurality of metal layer of different materials).
As taught by Fung, one of ordinary skill in the art would utilize and modify the above teaching into Liao in view of Wang to obtain and achieve the semiconductor structure comprising: the contact structure further comprising: a second metal silicide layer, and wherein a composition of the first metal silicide layer is different from a composition of the second metal silicide layer as claimed, because different silicide materials exhibit different electrical and thermal characteristics, and incorporating multiple silicide materials within a single contact structure allows optimization of source/drain contact performance [0020, 0032].
Thus, it would have been obvious to one of ordinary skill in the art before the effective filling date of the claimed invention to employ the teaching as taught by Fung in combination with Liao in view of Wang due to above reason.
Regarding claim 22, Liao in view of Wang and Fung teaches the semiconductor structure of claim 21, further comprising: an isolation feature (Liao: 214, Fig. 4, [0023]) over the substrate (202) and interfacing sidewalls of the base fin portion (209).
Regarding claim 23, Liao in view of Wang and Fung teaches the semiconductor structure of claim 21, further comprising:
a lower contact etch stop layer (CESL) (Liao: 230, Figs. 12A and 12B, [0032]) over the p-type source/drain feature (228S and 228D);
a lower interlayer dielectric (ILD) layer (232, Figs. 12A and 12B, [0032]) over the lower CESL (230);
an upper CESL (246, Figs. 15A and 15B, [0038]) over the n-type source/drain feature (244S and 244D); and
an upper ILD layer (248, Figs. 15A and 15B, [0038]) over the upper CESL (246).
Regarding claim 24, Liao in view of Wang and Fung teaches the semiconductor structure of claim 23, wherein the contact structure (Liao: 260 and 234) extends through the upper ILD layer (248), the upper CESL layer (246), the lower ILD layer (232), and the lower CESL (230).
Regarding claim 25, Liao in view of Wang and Fung teaches the semiconductor structure of claim 21, Liao in view of Wang does not teach the semiconductor structure wherein the first metal silicide layer comprises Ti.
Fung teaches the semiconductor structure wherein the first metal silicide layer comprises Ti (802 includes TiSi, [0032]).
It would have been obvious to one of ordinary skill in the art before the effective filling date of the claimed invention to employ and modify the teachings of Fung to obtain and achieve the semiconductor structure wherein the first metal silicide layer comprises Ti as claimed, because Ti is a well-known material and widely used as a silicide layer in the art. Further, 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 used a matter of obvious design choice. In re Leshin, 277 F.2d 197, 125 USPQ 416 (CCPA 1960).
Regarding claim 26, Liao in view of Wang and Fung teaches the semiconductor structure of claim 21, Liao in view of Wang does not teach the semiconductor structure wherein the second metal silicide layer comprises tungsten (W), molybdenum (Mo), ruthenium (Ru), nickel (Ni), or cobalt (Co).
Fung teaches the semiconductor structure wherein the second metal silicide layer comprises W, Mo, Ru, Ni, or Co (802 includes NiSi, [0032]).
It would have been obvious to one of ordinary skill in the art before the effective filling date of the claimed invention to employ and modify the teachings of Fung to obtain and achieve the semiconductor structure wherein the second metal silicide layer comprises W, Mo, Ru, Ni, or Co as claimed, because Ni is a well-known material and widely used as a silicide layer in the art. Further, 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 used a matter of obvious design choice. In re Leshin, 277 F.2d 197, 125 USPQ 416 (CCPA 1960).
Regarding claim 27, Liao in view of Wang and Fung teaches the semiconductor structure of claim 21, Liao in view of Fung does not teach the semiconductor structure, wherein the dipole layer comprises Zr, Hf, Sb, Ce, Sc, Y, Yb, or Er.
Wang teaches the semiconductor structure wherein the dipole layer comprises Zr, Hf, Sb, Ce, Sc, Y, Yb, or Er (144 includes Zr, Hf, Ce, Sc, Y, Yb, or Er, [0029]).
It would have been obvious to one of ordinary skill in the art before the effective filling date of the claimed invention to employ and modify the teachings of Wang to obtain and achieve the semiconductor structure wherein the dipole layer comprises Zr, Hf, Sb, Ce, Sc, Y, Yb, or Er as claimed, because Zr, Hf, Ce, Sc, Y, Yb, or Er are well-known materials and widely used as a silicide layer in the art. Further, 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 used a matter of obvious design choice. In re Leshin, 277 F.2d 197, 125 USPQ 416 (CCPA 1960).
Regarding claim 28, Liao teaches a semiconductor structure (200, Figs. 17A and 17B, [0042]) comprising:
a fin-shaped structure (209, Fig. 3, [0022]) arising from a substrate (202);
an isolation feature (214, Fig. 4, [0023]) surrounding the fin-shaped structure (209);
a first type epitaxial feature (228S and 228D, Figs. 11A and 11B, [0031]) disposed over the fin structure (209);
a lower contact etching stop layer (CESL) (230, Figs. 12A and 12B, [0032]) disposed on the first type epitaxial feature (228S and 228D) and the isolation feature (209);
a lower dielectric layer (232, Figs. 12A and 12B, [0032]) disposed over the lower CESL (236);
a second type epitaxial feature (244S and 244D, Figs. 15A and 15B, [0038]) disposed over the lower dielectric layer (232);
an upper CESL (246, Figs. 15A and 15B, [0038]) disposed on the lower dielectric layer (232) and the second type epitaxial feature (244S and 244D);
an upper dielectric layer (248, Figs. 15A and 15B, [0038]) disposed over the upper CESL (246); and
a contact structure (260 and 234, Figs. 16A and 16B, [0039]) extending through the second-type source/drain feature (244S and 244D) and terminating in the first-type source/drain feature (228S and 228D),
wherein the contact structure (260 and 234) interfaces the second-type source/drain feature (244S and 244D),
wherein the contact structure (260 and 234) interfaces the first-type source/drain feature (228S and 228D).
Liao does not teach the semiconductor structure comprising: the contact structure interfaces the source/drain features by way of a dipole layer, a first metal silicide layer.
Wang teaches a semiconductor structure (100, FIGS. 1B and 1C, [0020]) comprising: the contact structure (120, [0023]) interfaces the source/drain features (110, [0021, 0026, 0065]) by way of a dipole layer (144, [0026]), a first metal silicide layer (132).
As taught by Wang, one of ordinary skill in the art would utilize and modify the above teaching into Mevellec to obtain and achieve the semiconductor structure comprising: the contact structure interfaces the source/drain features by way of a dipole layer, a first metal silicide layer as claimed, because it reduces contact resistance by lowering the Schottky barrier height at the S/D interface, thereby directly modulating the metal-semiconductor energy barrier [0018, 0030].
Thus, it would have been obvious to one of ordinary skill in the art before the effective filling date of the claimed invention to employ the teaching as taught by Wang in combination with Liao due to above reason.
Liao in view of Wang does not teach the semiconductor structure comprising: the contact structure further comprising: a second metal silicide layer, and wherein a composition of the first metal silicide layer is different from a composition of the second metal silicide layer.
Fung teaches a semiconductor structure (300, FIGS. 10A and 10B, [0035]) comprising: the contact structure (802 and 1002) further comprising: a second metal silicide layer (802 includes a plurality of metal layer, [0032]), and wherein a composition of the first metal silicide layer is different from a composition of the second metal silicide layer (802 includes a plurality of metal layer of different materials).
As taught by Fung, one of ordinary skill in the art would utilize and modify the above teaching into Liao in view of Wang to obtain and achieve the semiconductor structure comprising: the contact structure further comprising: a second metal silicide layer, and wherein a composition of the first metal silicide layer is different from a composition of the second metal silicide layer as claimed, because different silicide materials exhibit different electrical and thermal characteristics, and incorporating multiple silicide materials within a single contact structure allows optimization of source/drain contact performance [0020, 0032].
Thus, it would have been obvious to one of ordinary skill in the art before the effective filling date of the claimed invention to employ the teaching as taught by Fung in combination with Liao in view of Wang due to above reason.
Regarding claim 29, Liao in view of Wang and Fung teaches the semiconductor structure of claim 28, Liao in view of Wang does not teach the semiconductor structure wherein the first metal silicide layer comprises Ti, wherein the second metal silicide layer comprises tungsten (W), molybdenum (Mo), ruthenium (Ru), nickel (Ni), or cobalt (Co).
Fung teaches the semiconductor structure wherein the first metal silicide layer comprises Ti (802 includes TiSi, [0032]), wherein the second metal silicide layer comprises W, Mo, Ru, Ni, or Co (802 includes NiSi).
It would have been obvious to one of ordinary skill in the art before the effective filling date of the claimed invention to employ and modify the teachings of Fung to obtain and achieve the semiconductor structure wherein the first metal silicide layer comprises Ti, wherein the second metal silicide layer comprises W, Mo, Ru, Ni, or Co as claimed, because Ti and Ni are well-known materials and widely used as a silicide layer in the art. Further, 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 used a matter of obvious design choice. In re Leshin, 277 F.2d 197, 125 USPQ 416 (CCPA 1960).
Regarding claim 30, Liao in view of Wang and Fung teaches the semiconductor structure of claim 28, Liao in view of Fung does not teach the semiconductor structure, wherein the dipole layer comprises Zr, Hf, Sb, Ce, Sc, Y, Yb, or Er.
Wang teaches the semiconductor structure wherein the dipole layer comprises Zr, Hf, Sb, Ce, Sc, Y, Yb, or Er (144 includes Zr, Hf, Ce, Sc, Y, Yb, or Er, [0029]).
It would have been obvious to one of ordinary skill in the art before the effective filling date of the claimed invention to employ and modify the teachings of Wang to obtain and achieve the semiconductor structure wherein the dipole layer comprises Zr, Hf, Sb, Ce, Sc, Y, Yb, or Er as claimed, because Zr, Hf, Ce, Sc, Y, Yb, or Er are well-known materials and widely used as a silicide layer in the art. Further, 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 used a matter of obvious design choice. In re Leshin, 277 F.2d 197, 125 USPQ 416 (CCPA 1960).
Regarding claim 31, Liao in view of Wang and Fung teaches the semiconductor structure of claim 28, wherein the first type epitaxial feature (Liao: 228S and 228D, Figs. 17A and 17B) and the second type epitaxial feature (244S and 244D) are disposed between two dielectric isolation structures (218, [0025]).
Conclusion
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/JIYOUNG OH/
Examiner, Art Unit 2818
/DUY T NGUYEN/Primary Examiner, Art Unit 2818 1/21/26