DETAILED ACTION
Notice of Pre-AIA or AIA Status
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
Response to Arguments
Applicant's amendments and arguments filed 8/17/2026 have been fully considered; the office action has been updated to address the newly amended limitations.
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.
Claims 31-36 are rejected under 35 U.S.C. 112(b) or 35 U.S.C. 112 (pre-AIA ), second paragraph, as being indefinite for failing to particularly point out and distinctly claim the subject matter which the inventor or a joint inventor (or for applications subject to pre-AIA 35 U.S.C. 112, the applicant), regards as the invention.
Claim 31 includes the final limitation “wherein a width of a bottom surface of the second contact structure is smaller than a width of a bottom surface of the second contact structure”; “the second contact structure” is repeated twice.
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.
Claims 31 and 34-37 are rejected under 35 U.S.C. 103 as being unpatentable over Tsai et al (U.S. Pub #2021/0098583), in view of Lee (U.S. Pub #2019/0074362).
With respect to claim 31, Tsai teaches a method for forming a semiconductor structure, comprising:
forming a first stack structure and a second stack structure over a substrate (see Fig. 22BB for multiple stack structures), wherein the first stack structure and the second stack structure comprises first semiconductor material layers and second semiconductor material layers alternately stacked (Paragraph 41 and 46);
removing a portion of the first stack structure and a portion of the second stack structure to form a first S/D recess and a second S/D recess (Figs. 9A-9B and Paragraph 58);
forming a first S/D structure in the first S/D recess and a second S/D structure in the second S/D recess (Figs. 12A-12B, 38; Paragraph 61);
forming a dielectric layer (Fig. 13A-13B, 40 and Paragraph 64) over the first S/D structure and the second S/D structure;
removing a portion of the first stack structure to form a plurality of first nanostructures (Fig. 14B, 28);
performing a first etching process to form a first trench in the first S/D structure and a second trench in the second S/D structure (Figs. 17A-17B);
wherein a bottom surface of the first trench is lower than a top surface of a bottommost first nanostructure (Fig. 17B, trench extends lower than bottommost portion 28; see dimension D2); and
forming a first contact structure (Fig. 18, 50) in the first trench and a second contact structure in the second trench,
wherein a width of a bottom surface of the second contact structure is smaller than a width of a bottom surface of the second contact structure.
Tsai does not teach
forming an opening to expose a top surface of the first S/D structure and a top surface of the second S/D structure;
forming a barrier layer in the opening;
performing a second etching process to enlarge the first trench and the second trench to form an enlarged first trench.
Lee teaches
forming an opening (Fig. 19, 170pt) to expose a top surface of the S/D structure;
forming a barrier layer (Fig. 20, 175) in the opening;
performing a first etching process (Fig. 21) to form a first trench in the S/D structure (Fig. 16, 150);
performing a second etching process (Fig. 22) to enlarge the first trench and the second trench to form an enlarged first trench.
It would have been obvious to one of ordinary skill in the art before the effective date of the claimed invention to provide a barrier layer in an opening over the first and second S/D structures of Tsai and to perform the first and second etching processes as taught by Lee in order to achieve the predictable result of increasing the contact surface are between the first and second contact structures and the source/drain materials (Paragraph 157).
With respect to claim 34, Tsai does not teach forming a contact etch stop layer over the first S/D structure, wherein the barrier layer interfaces with the contact etch stop layer.
Lee teaches forming a contact etch stop layer over the first S/D structure (Fig. 20, 195), wherein the barrier layer (Fig. 20, 175) interfaces with the contact etch stop layer.
It would have been obvious to one of ordinary skill in the art before the effective date of the claimed invention to provide a barrier layer and contact etch stop layer as taught by Lee in order to achieve the predictable result of increasing the contact surface are between the first and second contact structures and the source/drain materials (Paragraph 157)
With respect to claim 35, Tsai teaches forming a metal silicide layer (Fig. 18, 52 and Paragraph 76) between the first S/D structure and the first contact structure,
but does not teach wherein the metal silicide layer has a step-shaped structure.
Lee teaches a metal silicide layer (Fig. 23, 160 and Paragraph 156) having a step-shaped structure.
It would have been obvious to one of ordinary skill in the art before the effective date of the claimed invention to form the silicide layer of Tsai to have a step shape as taught by Lee in order to achieve the predictable result of increasing the contact surface are between the first and second contact structures and the source/drain materials (Paragraph 157)
With respect to claim 36, Tsai teaches forming a dummy gate structure (Fig. 7A, 33 and Paragraph 53) over the first stack structure; and
forming a gate spacer layer (Fig. 9B, 36 and Paragraph 57) adjacent to the dummy gate structure, wherein a bottom surface of the first trench is lower than a bottom surface of the gate spacer layer (Fig. 17B, 36).
With respect to claim 37, Tsai teaches forming a fin spacer layer (Figs. 8A-9A, residual portion 36) adjacent to the first S/D structure, wherein a bottom surface of the first contact structure is lower than a top surface of the fin spacer layer (Fig. 18, D3 is below the height of bottommost portions 42).
Claim 32 rejected under 35 U.S.C. 103 as being unpatentable over Tsai and Lee, in view of Han et al (U.S. Pub #2023/0395667).
With respect to claim 32, Tsai and Lee do not teach forming a sacrificial layer on the barrier layer in the opening; and performing the first etching process by using the barrier layer and the sacrificial layer as a mask to form the first trench, wherein a bottom surface of the first trench is lower than a bottom surface of the sacrificial layer.
Han teaches
forming a sacrificial layer (Fig. 31, 174P) on a barrier layer (Fig. 31, 172P) in the opening; and performing the first etching process by using the barrier layer and the sacrificial layer as a mask to form the trench (fig. 32, 170_H), wherein a bottom surface of the trench is lower than a bottom surface of the sacrificial layer.
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to provide a sacrificial layer and barrier structure in the opening of Tsai and Lee as taught by Han in order to achieve the predictable result of utilizing the barrier layer and sacrificial layer with a directional etching process to form a trench in the source/drain region (Fig. 32 and Paragraph 244).
Allowable Subject Matter
Claims 17, 18, and 20-30 are allowed.
Claim 33 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.
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 BENJAMIN P SANDVIK whose telephone number is (571)272-8446. The examiner can normally be reached M-F: 10-6.
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/BENJAMIN P SANDVIK/Primary Examiner, Art Unit 2812
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