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 Amendment
Applicant’s amendment filed on 1/16/2026 is acknowledged. Claims 1, 5-6, 8, 10, 21 have been amended.
Response to Arguments
Applicant’s arguments with respect to claims 1-20 have been considered but are moot because the new ground of rejection does not rely on any reference applied in the prior rejection of record for any teaching or matter specifically challenged in the argument.
Claim Rejections - 35 USC § 102
The following is a quotation of the appropriate paragraphs of 35 U.S.C. 102 that form the basis for the rejections under this section made in this Office action:
A person shall be entitled to a patent unless –
(a)(1) the claimed invention was patented, described in a printed publication, or in public use, on sale, or otherwise available to the public before the effective filing date of the claimed invention.
(a)(2) the claimed invention was described in a patent issued under section 151, or in an application for patent published or deemed published under section 122(b), in which the patent or application, as the case may be, names another inventor and was effectively filed before the effective filing date of the claimed invention.
Claims 1, 5-9 are rejected under 35 U.S.C. 102(a)(1) as being anticipated by Chang et al. (US 2018/0040559 A1).
Regarding claim 1, Chang teaches a method (method in Figs. 1-5 of embodiment in Fig. 8B of Chang. Fig. 8B is an alternative embodiment of Fig. 5 of Chang), comprising:
receiving a workpiece (structure 100 in Fig. 1 of Chang) comprising:
a channel region (region of fins 107 covered by the dummy gate 111) over a substrate (101),
a source/drain feature (201 in Fig. 2A of Chang) adjacent to the channel region,
a gate structure (111 in Fig. 1 of Chang) over the channel region, and
a dielectric structure (203 in Fig. 2A) over the source/drain feature;
forming a contact opening (305 in Fig. 3) penetrating through the dielectric structure to expose the source/drain feature;
forming a silicide layer (silicide contact layer described in [0053] of Chang) in the contact opening and on the source/drain feature;
forming a tungsten-containing layer (first contact 401 in Fig. 4 of Chang, which is made of W, as described in [0054] of Chang) in the contact opening and on the silicide layer; and
forming a conductive layer (501 in Figs. 5 and 8B of Chang) in the contact opening and on the tungsten-containing layer, wherein a composition of the conductive layer is different from a composition of the tungsten-containing layer (as described in [0064] of Chang, the second contact 501 is made of material such as Al, Cu… different than W), and wherein in a first cross-sectional view cut through the gate structure and the source/drain feature, a topmost surface of the tungsten-containing layer is a convex surface (as shown in Fig. 8B of Chang).
Regarding claim 5, Chang teaches all limitations of the method of claim 1, and also teaches wherein the silicide layer comprises a concave top surface (as described in [0053] of Chang, the silicide layer is a portion of the top surface of S/D region 201 converted into silicide material so its top surface, which consist of a flat middle portion and two vertical sidewalls, is a concave surface) in the first cross-sectional view (the view shown in Fig. 3 of Chang) and a substantially flat top surface (flat top surface in the middle of the trench 305) in a second cross-sectional view (the view in-out of the page in Fig. 3 of Chang) cut through the source/drain feature without cutting through the gate structure.
Regarding claim 6, Chang teaches all limitations of the method of claim 5, and also teaches wherein, in the first cross-sectional view, a topmost point of the convex top surface of the tungsten-containing layer is above a topmost point of a top surface of the source/drain feature (as shown in Fig. 8B of Chang).
Regarding claim 7, Chang teaches all limitations of the method of claim 5, and also teaches wherein, in the second cross-sectional view, a thickness of the silicide layer is not uniform (as implied by the concave shape of the top surface of the S/D region 201 in Fig. 3 of Chang, the thickness of the silicide layer, as measured from the flat surface of the trench 305, is not uniform).
Regarding claim 8, Chang teaches all limitations of the method of claim 5, and also teaches wherein, in the first cross-sectional view, a lower portion of the tungsten-containing layer (portion of 401 that extends into the S/D region 201 in Fig. 8B of Chang) extends into the source/drain feature, an upper portion (portion of 401 that is above the S/D region 201) of the tungsten-containing layer is above the source/drain feature, and an entirety of the conductive layer is above the source/drain feature (as shown in Fig. 8B of Chang).
Regarding claim 9, Chang teaches all limitations of the method of claim 1, and also teaches wherein a portion of the tungsten-containing layer (401) is in direct contact with a portion of a bottom surface (interface of 203 and 201 in Fig. 8B of Chang) of the dielectric structure.
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.
Claim 2 is rejected under 35 U.S.C. 103 as being unpatentable over Chang, as applied in claim 1 above, and further in view of Kawamura et al. (US 8076239 B2).
Regarding claim 2, Chang teaches all limitations of the method of claim 1, but does not teach the method further comprising: before the forming of the tungsten-containing layer, performing a cleaning process to the silicide layer to remove an oxidized portion of the silicide layer.
Kawamura teaches a method of forming an S/D contact structure to a transistor (Figs. 24A-26A of Kawamura). The method comprises: forming an opening to a silicide layer (34 in Fig. 24A of Kawamura) on S/D regions (21); performing a cleaning of silicide surface to remove any oxidized portion (as described in column 8 lines 41-56 of Kawamura).
Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date of the claimed invention to have cleaned the surface of silicide in Kim’s method in order to have a better contact structure.
Claim 3 is rejected under 35 U.S.C. 103 as being unpatentable over Chang, as applied in claim 1 above, and further in view of Wang et al. (US 2018/0151429 A1) and Hsieh et al. (US 10083863 B1).
Regarding claim 3, Chang teaches all limitations of the method of claim 1, but does not teach wherein the forming of the tungsten-containing layer comprises performing a physical vapor deposition (PVD) process, and the forming of the conductive layer comprises performing a chemical vapor deposition (CVD) process.
Wang teaches that a metal material (64 in Fig. 10 of Wang) can be filled into a contact structure using PVD process (see [0034] of Wang. Other method such as MOCVD or plating can be used, as disclosed by Wang, however, PVD is preferred because it is less complicated than MOCVD and is more controlled and precise than plating).
Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date of the claimed invention to have formed the W contact 401 of Chang using PVD as disclosed by Wang for simplicity while maintaining quality and control of the deposited film.
But Chang in view of Wang does not teach that wherein the forming of the conductive layer comprises performing a chemical vapor deposition (CVD) process.
Hsieh teaches that a metal material (334 in Fig. 17 of Hsieh) such as Al, Cu… can be filled into a contact structure using CVD process (see column 20 lines 54-57 of Hsieh).
Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date of the claimed invention to have formed the conductive layer of Chang using CVD process. This is a common technique for high quality deposition of material.
Claim 4 is rejected under 35 U.S.C. 103 as being unpatentable over Chang, as applied in claim 1 above, and further in view of Khaderbad et al. (US 2021/0184018 A1).
Regarding claim 4, Chang teaches all limitations of the method of claim 1, and also teaches wherein the tungsten-containing layer comprises tungsten (W) (as taught in claim 1 above), but does not teach that the conductive layer comprises ruthenium (Ru), molybdenum (Mo), or cobalt (Co).
Khaderbad teaches an S/D contact structure (132-134 in Fig. 1B of Khaderbad) comprising: a silicide layer (132A), a lower via (132C), and an upper via (134B) comprising of Ru (see [0069] of Khaderbad).
Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date of the claimed invention to have used Ru in conductive layer of Chang, as disclosed by Khaderbad, in order to have high conductivity and corrosion resistance for contact structure.
Claims 10, 13-15 are rejected under 35 U.S.C. 103 as being unpatentable over Kim et al. (US 2017/0148797 A1) in view of Chang.
Regarding claim 10, Kim teaches a method (Figs. 60-100 of Kim), comprising:
receiving a workpiece (structure in Fig. 61 of Kim) comprising a first region (PMOS region II, as stated in [0197] of Kim) and a second region (NMOS region III, as stated in [0197] of Kim), the workpiece comprising:
a first gate structure (444 in Fig. 63) over channel regions of a first fin (left fin 404 in Fig. 61) and a second fin (right fin 404) over the first region,
a p-type source/drain feature (524 in Fig. 70) disposed and spanning over the first fin and the second fin,
a second gate structure (446 in Fig. 63) over channel regions of a third fin (left fin 406 in Fig. 61) and a fourth fin (right fin 406) over the second region,
an n-type source/drain feature (526 in Fig. 83 of Kim) disposed and spanning over the third fin and the fourth fin over the second region, and
a dielectric structure (530 to 600 in Fig. 90 of Kim) over the p-type source/drain feature and the n-type source/drain feature;
forming a first contact opening (614 in Fig. 90) extending through the dielectric structure to expose the p-type source/drain feature and a second contact opening (616 in Fig. 90) extending through the dielectric structure to expose the n-type source/drain feature;
after the forming of the first contact opening and the second contact opening, performing a first deposition process to form a first conductive layer (644 in Fig. 100) in the first contact opening and a second conductive layer (646 in Fig. 100) in the second contact opening,
But Kim does not teach that wherein the first conductive layer is formed in a lower portion of the first contact opening without being formed in an upper portion of the first contact opening; and the method comprising: performing a second deposition process to form a third conductive layer in the first contact opening and over first conductive layer and a fourth conductive layer in the second contact opening and over the second conductive layer; and wherein the first deposition process is different than the second deposition process, and a composition of the first and second conductive layers is different than a composition of the third and fourth conductive layers.
Chang teaches a method (method in Figs. 1-5 of embodiment in Fig. 8B of Chang. Fig. 8B is an alternative embodiment of Fig. 5 of Chang), comprising: forming a structure having channel region (region of fins 107 covered by the dummy gate 111) over a substrate (101), a source/drain feature (201 in Fig. 2A of Chang) adjacent to the channel region, a gate structure (111 in Fig. 1 of Chang) over the channel region, and a dielectric structure (203 in Fig. 2A) over the source/drain feature; forming a contact opening (305 in Fig. 3) penetrating through the dielectric structure to expose the source/drain feature; forming a silicide layer (silicide contact layer described in [0053] of Chang) in the contact opening and on the source/drain feature; forming a first conductive layer (first contact 401 in Fig. 4 of Chang, which is made of W, as described in [0054] of Chang) in the contact opening and on the silicide layer; and forming a second conductive layer (501 in Figs. 5 and 8B of Chang) in the contact opening and on the first conductive layer, wherein a composition of the conductive layer is different from a composition of the tungsten-containing layer (as described in [0064] of Chang, the second contact 501 is made of material such as Al, Cu… different than W).
Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date of the claimed invention to have formed the S/D contact structures 654 and 656 of Kim using the method of Chang in order to prevent bubble or voids problems in filling of metal material into a long/deep via (filling high aspect ratio tends to cause bubble or void formed inside the via, which leads to low performance of the contact structure).
As incorporated, the insulation layer 530 in Fig. 100 of Kim is analogous to 203 in Fig. 8B of Chang, and 600 of Kim is analogous to 405 of Chang. So instead of forming one long contact plug (such as 654, 656 of Kim), the contact structure would involve forming two conductive layers - a first conductive layer 401 in the first insulation layer 530, and a second conductive layer 501 in the second insulation layer 600.
Regarding claim 13, Kim in view of Chang teaches all limitations of the method of claim 10, and also teaches wherein a depth of the first contact opening is less than a depth of the second contact opening (as indicated in Fig. 100 of Kim, the opening 616 has a depth L7 that is greater than depth L2 of opening 614).
Regarding claim 14, Kim in view of Chang teaches all limitations of the method of claim 10, and also teaches wherein a thickness of the third conductive layer is less than a thickness of the fourth conductive layer (as shown in Fig. 100, 646 has thickness L7 that is greater than thickness L2 of 644).
Regarding claim 15, Kim in view of Chang teaches all limitations of the method of claim 10, and further comprising:
before the performing of the first deposition process, forming a first silicide layer (624 in Fig. 100 of Kim) in the first contact opening and forming a second silicide layer (626 in Fig. 100 of Kim) in the second contact opening,
wherein, in a cross-sectional view, a top surface of the first silicide layer and a top surface of the second silicide layer are substantially flat (as shown in Fig. 100 of Kim, 624 and 626 are mostly flat besides the concave point at the center of 626).
Claim 11 is rejected under 35 U.S.C. 103 as being unpatentable over Chang, as applied in claim 10 above, and further in view of Wang and Hsieh.
Regarding claim 11, Kim in view of Chang teaches all limitations of the method of claim 10, but does not teach wherein the first deposition process comprises a physical vapor deposition (PVD) process, and the second deposition process comprises a chemical vapor deposition (CVD) process.
Wang teaches that a metal material (64 in Fig. 10 of Wang) can be filled into a contact structure using PVD process (see [0034] of Wang. Other method such as MOCVD or plating can be used, as disclosed by Wang, however, PVD is preferred because it is less complicated than MOCVD and is more controlled and precise than plating).
Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date of the claimed invention to have formed the W contact 401 of Chang using PVD as disclosed by Wang for simplicity while maintaining quality and control of the deposited film.
But Kim-Chang-Wang does not teach that the second deposition process comprises a chemical vapor deposition (CVD) process.
Hsieh teaches that a metal material (334 in Fig. 17 of Hsieh) such as Al, Cu… can be filled into a contact structure using CVD process (see column 20 lines 54-57 of Hsieh).
Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date of the claimed invention to have formed the conductive layer of Chang using CVD process. This is a common technique for high quality deposition of material.
Claim 12 is rejected under 35 U.S.C. 103 as being unpatentable over Chang, as applied in claim 10 above, and further in view of Khaderbad.
Regarding claim 12, Kim in view of Chang teaches all limitations of the method of claim 10, and also teaches wherein the first and second conductive layers comprise tungsten (W) (as taught in claim 11 above), but does not teach that the third and fourth conductive layers comprise ruthenium (Ru), molybdenum (Mo), or cobalt (Co).
Khaderbad teaches an S/D contact structure (132-134 in Fig. 1B of Khaderbad) comprising: a silicide layer (132A), a lower via (132C), and an upper via (134B) comprising of Ru (see [0069] of Khaderbad).
Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date of the claimed invention to have used Ru in conductive layer of Chang, as disclosed by Khaderbad, in order to have high conductivity and corrosion resistance for contact structure.
Claim 16 is rejected under 35 U.S.C. 103 as being unpatentable over Kim in view of Chang, as applied in claim 10 above, and further in view of Hsieh.
Regarding claim 16, Kim in view of Chang teaches all limitations of the method of claim 10, but does not teach the method further comprising: after the performing of the first deposition process and before the performing of the second deposition process, forming a barrier layer in the first and second contact openings and over the first and second conductive layers.
Hsieh teaches a method of forming an S/D contact structure (Figs. 10-15 of Hsieh) comprising: depositing a first barrier layer (230 in Fig. 11 of Hsieh); forming a lower component (232) extends from the top surface of the S/D region (207) up to a level of the top surface of the gate structure; forming a barrier layer (229 in Fig. 12) and then forming the upper conductive component (234) extends from the top surface of the gate structure and up.
Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date of the claimed invention to have formed a multiple components S/D contact structure as disclosed by Hsieh in order to form high quality contact structure in a more controllable way. The barrier layer 229 prevents metal from diffusing out into the surrounding dielectric material.
Claims 21-23 are rejected under 35 U.S.C. 103 as being unpatentable over Chang in view of Kim et al. (US 2017/0148797 A1).
Regarding claim 21, Chang teaches a method (method in Figs. 1-5 of embodiment in Fig. 8B of Chang. Fig. 8B is an alternative embodiment of Fig. 5 of Chang), comprising:
forming a first fin-shaped structure (left fin 107 in Fig. 1 of Chang) and a second fin-shaped structure (right fin 107) over a substrate (101), the first fin-shaped structure and the second fin-shaped structure extending lengthwise along a first direction (lengthwise of the fin);
forming a gate structure (gate 111 in Fig. 1 of Chang) over the first fin-shaped structure and the second fin-shaped structure, the gate structure extending lengthwise along a second direction (direction of the gates 111) different from the first direction;
recessing the first fin-shaped structure and the second fin-shaped structure (as described in [0034] of Chang) to form a source/drain opening (recess formed by the removal of portions of fins 107 not covered by the gates 111);
epitaxially growing a source/drain feature (201 in Fig. 2A, as described in [0035] of Chang) in the source/drain opening;
forming a silicide layer (silicide contact layer described in [0053] of Chang) extended into the source/drain feature;
forming a first conductive layer (first contact 401 in Fig. 4 of Chang, which is made of W, as described in [0054] of Chang) on the silicide layer, wherein the first conductive layer has a non-uniform thickness and a convex top surface in a cross-sectional view (as shown in Fig. 8B of Chang); and
forming a second conductive layer (501 in Figs. 5 and 8B of Chang) on the first conductive layer, wherein the first and second conductive layer have different compositions (as described in [0064] of Chang, the second contact 501 is made of material such as Al, Cu… different than W).
But Chang does not teach that wherein the source/drain feature comprises a first layer and a second layer, a concentration of a dopant in the first layer varies from a concentration of the dopant in the second layer
Kim teaches a method of forming epitaxial S/D structures (222/224 in Figs. 26-27 of Kim) wherein the source/drain feature comprises a first layer (202a/204a) and a second layer (202c/204c), a concentration of a dopant in the first layer varies from a concentration of the dopant in the second layer (as described in [0132]-[0144] of Kim, the impurity dopant of 202c/204c is higher than that of 202a/204a).
Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date of the claimed invention to have formed the source/drain structure of Chang as disclosed by Kim in order to have applied a stress onto the channel, thereby increase carrier mobility in the device.
Regarding claim 22, Chang in view of Kim teaches all limitations of the method of claim 21, and also teaches wherein the convex top surface is above a topmost surface of the source/drain feature (as shown in Fig. 8B of Chang).
Regarding claim 23, Chang in view of Kim teaches all limitations of the method of claim 21, and also teaches wherein in another cross-sectional view (view in/out of the page) different from the cross-sectional view, the first conductive layer has a substantially planar top surface (the claim language does not specify how large the planar top surface must be. As such, it can be of any size. So this is satisfied in Fig. 8B of Chang).
Claim 24 is rejected under 35 U.S.C. 103 as being unpatentable over Chang in view of Kim, as applied in claim 21 above, and further in view of Khaderbad.
Regarding claim 24, Chang in view of Kim teaches all limitations of the method of claim 21, and also teaches wherein the first conductive layer comprises tungsten (as taught in claim 21 above), but does not teach the second conductive layer comprises ruthenium (Ru), molybdenum (Mo), or cobalt (Co).
Khaderbad teaches an S/D contact structure (132-134 in Fig. 1B of Khaderbad) comprising: a silicide layer (132A), a lower via (132C), and an upper via (134B) comprising of Ru (see [0069] of Khaderbad).
Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date of the claimed invention to have used Ru in conductive layer of Chang, as disclosed by Khaderbad, in order to have high conductivity and corrosion resistance for contact 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 TUAN A HOANG whose telephone number is (571)270-0406. The examiner can normally be reached Monday-Friday 8-9am, 10am-6pm EST.
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If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Jessica Manno can be reached at (571) 272-2339. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300.
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/Tuan A Hoang/ Primary Examiner, Art Unit 2898
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