DETAILED ACTION
Claim Rejections - 35 USC § 103
The text of those sections of Title 35, U.S. Code not included in this action can be found in a prior Office action.
Claims 11-13 and 15 rejected under 35 U.S.C. 103 as being unpatentable over Hsieh (U.S. PGPub 2018/0158727) in view of Kim 738 (U.S. PGPub 2022/0246738).
Regarding claim 11, Hsieh teaches a method for forming a semiconductor device structure, comprising: forming an epitaxial structure beside a channel structure (Fig. 3E, 320, [0033], 310, [0017]); forming a dielectric layer surrounding and covering the epitaxial structure (Fig. 3F, 340, [0037]); partially removing the dielectric layer to form a contact opening exposing the epitaxial structure (Fig. 3K, 353, [0040]); forming a protective structure over sidewalls of the contact opening, wherein the protective structure has an inner portion and an outer portion, the inner portion is between the outer portion and the dielectric layer, and the outer portion has a higher atomic concentration of nitrogen than that of the inner portion (Fig. 3K-3L, 360/370, [0041]-[0042], same materials as 160/170; [0027] 160 may be silicon oxide, [0028] 170 may be silicon nitride); forming a metal-semiconductor compound feature on the epitaxial structure after the protective structure is formed (Fig. 3P, 380, [0044]), and forming a conductive contact filling the contact opening (Fig. 3P, 390, [0045]).
Hsieh does not explicitly teach wherein an interface between the conductive contact and the inner portion of the protective structure is positioned above a topmost surface of the epitaxial structure.
Kim 738 teaches a protective structure comprising a first protective layer and second protective layer on a contact opening to an epitaxial source/drain region (Fig. 2C, 160, [0062], [0034]), and forming a metal-semiconductor compound feature on the epitaxial source/drain region after the protective structure is formed (Figs. 11I-11J, 152, [0037]), wherein an interface between the contact and the inner portion of the protective structure is positioned above a topmost surface of the epitaxial structure (Fig. 2C).
Therefore it would have been obvious to a person having ordinary skill in the art before the time of the effective filing date to combine the teachings of Kim 738 with Hsieh such that an interface between the conductive contact and the inner portion of the protective structure is positioned above a topmost surface of the epitaxial structure because the prior art teaches every element, a person of ordinary skill could have combined them as claimed and in combination each element performs the same function as it does separately, and the combination would have yielded predictable results to one of ordinary skill in the art before the time of the invention. See MPEP 2143(I)A.
Regarding claim 12, the combination of Hsieh and Kim 738 teaches wherein the metal-semiconductor compound feature is between the conductive contact and the epitaxial structure (Hsieh, Fig. 3P; Kim 738, Fig. 2).
Regarding claim 13, the combination of Hsieh and Kim 738 teaches wherein the metal-semiconductor compound feature is formed before the conductive contact is formed (Hsieh, Fig. 3O-3P, 380, [0044]).
Regarding claim 15, the combination of Hsieh and Kim 738 teaches wherein the inner portion of the protective structure has a lower dielectric constant than that of the outer portion of the protective structure (Hsieh, [0041]-[0042], same materials as 160/170; [0027] 160 may be silicon oxide, [0028] 170 may be silicon nitride; silicon oxide has lower dielectric constant).
Claims 1-5 and 7-8 are rejected under 35 U.S.C. 103 as being unpatentable over Chen (U.S. PGPub 2022/0028994) in view of Hsieh (U.S. PGPub 2018/0158727) and Kim 738 (U.S. PGPub 2022/0246738).
Regarding claim 1, Chen teaches a method for forming a semiconductor device structure, comprising: forming a metal gate stack wrapped around a plurality of semiconductor nanostructures, wherein the semiconductor nanostructures are adjacent to an epitaxial structure (Fig. 21C, 54/55, [0043]; 102, [0078]; 92, [0066]); forming a dielectric layer over the metal gate stack and the epitaxial structure (106, [0084]); partially removing the dielectric layer to form a contact opening exposing the epitaxial structure (Fig. 22B, [0085]); forming a metal-semiconductor compound feature on the epitaxial structure after the second protective layer is formed (Fig. 23C, [0086]-[0087]) and forming a conductive contact over the epitaxial layer to fill the contact opening (Fig. 23B, 112, [0087]).
Chen does not explicitly teach forming a first protective layer over sidewalls of the contact opening; forming a second protective layer over the first protective layer, wherein the first protective layer has a lower dielectric constant than that of the second protective layer; and forming the conductive contact over the second protective layer.
Hsieh teaches a method for forming a semiconductor device structure, comprising a metal gate stack over a semiconductor structure adjacent to an epitaxial structure (Fig. 3I, 322, 320, [0033], [0035]); forming a dielectric layer over the metal gate stack and the epitaxial structure (352, [0039]), partially removing the dielectric layer to form a contact opening exposing the epitaxial structure (Fig. 3J, 353, [0040]), forming a first protective layer over sidewalls of the contact opening (Fig. 3K, 360, [0041]), forming a second protective layer over the first protective layer (Fig. 3L, 370, [0042]), wherein the first protective layer has a lower dielectric constant than that of the second protective layer ([0041]-[0042], 360/370 same materials as 160/170; [0027] 160 may be silicon oxide, [0028] 170 may be silicon nitride; SiN has higher dielectric constant); forming a metal-semiconductor compound feature on the epitaxial structure after the protective structure is formed (Fig. 3P, 380, [0044]); and forming a conductive contact over the second protective layer and the epitaxial layer to fill the contact opening (390, [0045]).
Therefore it would have been obvious to a person having ordinary skill in the art before the time of the effective filing date to combine the teachings of Hsieh with Chen such that the method comprises forming a first protective layer over sidewalls of the contact opening; forming a second protective layer over the first protective layer, wherein the first protective layer has a lower dielectric constant than that of the second protective layer; and forming the conductive contact over the second protective layer for the purpose of protecting the metal gate during cleaning (Hsieh, [0043]).
Chen does not explicitly teach wherein an interface between the conductive contact and the inner portion of the protective structure is positioned above a topmost surface of the epitaxial structure.
Kim 738 teaches a protective structure comprising a first protective layer and second protective layer on a contact opening to an epitaxial source/drain region (Fig. 2C, 160, [0062], [0034]), and forming a metal-semiconductor compound feature on the epitaxial source/drain region after the protective structure is formed (Figs. 11I-11J, 152, [0037]), wherein an interface between the contact and the inner portion of the protective structure is positioned above a topmost surface of the epitaxial structure (Fig. 2C).
Therefore it would have been obvious to a person having ordinary skill in the art before the time of the effective filing date to combine the teachings of Kim 738 with Chen such that an interface between the conductive contact and the inner portion of the protective structure is positioned above a topmost surface of the epitaxial structure because the prior art teaches every element, a person of ordinary skill could have combined them as claimed and in combination each element performs the same function as it does separately, and the combination would have yielded predictable results to one of ordinary skill in the art before the time of the invention. See MPEP 2143(I)A.
Regarding claim 2, the combination of Chen, Hsieh, and Kim 738 teaches wherein the metal-semiconductor compound feature is between the conductive contact and the epitaxial structure (Chen, Fig. 23C, [0086]-[0087]; Hsieh, Fig. 3P, 380, [0044]). It would have been obvious to a person having ordinary skill in the art to further combine the teachings of Chen, Hsieh, and Kim 738 for the reasons set forth in the rejection of claim 1.
Regarding claim 3, the combination of Chen, Hsieh, and Kim 738 teaches cleaning an exposed surface of the epitaxial structure after the second protective layer is formed and before the metal-semiconductor compound feature is formed (Hsieh, Fig. 3M, [[0043]).It would have been obvious to a person having ordinary skill in the art to further combine the teachings of Chen, Hsieh, and Kim 738 for the reasons set forth in the rejection of claim 1.
Regarding claim 4, the combination of Chen, Hsieh, and Kim 738 teaches wherein the second protective layer is at least partially consumed during the cleaning of the exposed surface of the epitaxial structure (Hsieh, Fig. 3M, [[0043]). It would have been obvious to a person having ordinary skill in the art to further combine the teachings of Chen, Hsieh, and Kim 738 for the reasons set forth in the rejection of claim 1.
Regarding claim 5, the combination of Chen, Hsieh, and Kim 738 teaches wherein the second protective layer has a higher atomic concentration of nitrogen than that of the first protective layer (Hsieh, [0027]-[0028], silicon oxide/silicon nitride). It would have been obvious to a person having ordinary skill in the art to further combine the teachings of Chen, Hsieh, and Kim 738 for the reasons set forth in the rejection of claim 1.
Regarding claim 7, the combination of Chen, Hsieh, and Kim 738 teaches forming a gate spacer over a sidewall of a dummy gate stack; and replacing the dummy gate stack with the metal gate stack, wherein the first protective layer is in direct contact with the gate spacer and the dielectric layer (Chen, Fig. 15E, 76, 81, [0055], [0071]; Figs. 18C-20C, [0076]-[0078]). It would have been obvious to a person having ordinary skill in the art to further combine the teachings of Chen, Hsieh, and Kim 738 for the reasons set forth in the rejection of claim 1.
Regarding claim 8, the combination of Chen, Hsieh, and Kim 738 teaches forming a second dielectric layer over the metal gate stack and the conductive contact; and forming a conductive via penetrating through the second dielectric layer and electrically connected to the conductive contact (Chen, Fig. 24C, 120, [0091]-[0094]). It would have been obvious to a person having ordinary skill in the art to further combine the teachings of Chen, Hsieh, and Kim 738 for the reasons set forth in the rejection of claim 1.
Claim 6 is rejected under 35 U.S.C. 103 as being unpatentable over Chen (U.S. PGPub 2022/0028994) in view of Hsieh (U.S. PGPub 2018/0158727), Kim 738 (U.S. PGPub 2022/0246738), and Wu (U.S. PGPub 2022/0262792).
Regarding claim 6, the combination of Chen, Hsieh, and Kim 738 teaches wherein the first protective layer is 1.8 nm (Hsieh, [0027]) and is silent on the thickness of the second protective layer.
Wu teaches wherein a silicon nitride protective layer in a contact opening for an epitaxial source/drain feature is 1-3 nm in thickness ([0058], Fig. 16B). In the case where the claimed ranges overlap or lie inside ranges disclosed by the prior art a prima facie case of obviousness exists. See MPEP 2144.05.
Therefore it would have been obvious to a person having ordinary skill in the art to combine the teachings of Wu with Chen, Hsieh, and Kim 738 such that the first protective layer is thicker than the second protective layer for the purpose of choosing an appropriate known thickness for each layer from the pertinent art.
Claims 9-10 are rejected under 35 U.S.C. 103 as being unpatentable over Chen (U.S. PGPub 2022/0028994) in view of Hsieh (U.S. PGPub 2018/0158727), Kim 738 (U.S. PGPub 2022/0246738), and Chen 468 (U.S. PGPub 2021/0098468).
Regarding claim 9, the combination of Chen, Hsieh, and Kim 738does not explicitly teach forming a second dielectric layer over the metal gate stack and the dielectric layer; and partially removing the second dielectric layer and the first dielectric layer to form the contact opening.
Chen 468 teaches a method for forming a semiconductor device structure, comprising a metal gate stack over a semiconductor structure adjacent to an epitaxial structure (Fig. 5, 222, 400, 212, [0049]-[0051]); forming a dielectric layer over the metal gate stack and the epitaxial structure (450, [0053]), forming a second dielectric layer over the metal stack and the dielectric layer (280, [0053]), and partially removing the dielectric layer and second dielectric layer to form a contact opening exposing the epitaxial structure (Fig. 8, 520).
Therefore it would have been obvious to a person having ordinary skill in the art before the time of the effective filing date to combine the teachings of Chen with Chen, Hsieh, and Kim 738such that the method comprises forming a second dielectric layer over the metal gate stack and the dielectric layer; and partially removing the second dielectric layer and the first dielectric layer to form the contact opening for the purpose of protecting the gate structures (Chen 468, [0053]).
Regarding claim 10, the combination of Chen, Hsieh, Kim 738, and Chen 468 teaches forming a third dielectric layer over the second dielectric layer and the conductive contact; and forming a conductive via penetrating through the third dielectric layer and electrically connected to the conductive contact (Chen, Fig. 24C, 120, [0091]-[0094]). It would have been obvious to a person having ordinary skill in the art to further combine the teachings of Chen, Hsieh, Kim 738, and Chen 468 for the reasons set forth in the rejection of claim 9.
Claim 14 is rejected under 35 U.S.C. 103 as being unpatentable over Hsieh (U.S. PGPub 2018/0158727) in view of Kim 738 (U.S. PGPub 2022/0246738) and Kim (U.S. PGPub 2016/0043197).
Regarding claim 14, Hsieh teaches cleaning the epitaxial structure before the metal-semiconductor compound feature is formed (Fig. 3M, [0043]) but does not explicitly teach wherein the protective structure becomes thinner after the cleaning of the epitaxial structure.
Wei teaches wherein a cleaning process on a silicon nitride barrier layer in a source/drain contact opening reduces the thickness of the barrier layer (Figs. 18-19, [0106]).
Therefore it would have been obvious to a person having ordinary skill in the art before the time of the effective filing date to combine the teachings of Wei with Hsieh and Kim 738 such that the protective structure becomes thinner after the cleaning of the epitaxial structure for the purpose of increasing the size of the contact hole (Wei, [0106]).
Allowable Subject Matter
Claims 16 and 18-21 are allowed.
The following is a statement of reasons for the indication of allowable subject matter:
Regarding independent claim 16, the prior art, alone or in combination, does not teach or suggest the limitation “wherein the first protective layer is spaced apart from the metal-semiconductor compound feature by the conductive contact” in combination with the rest of the claim limitations. The most relevant prior art has been cited in the rejections of independent claims 1 and 11. Claims 18-21 depend from and further limit claim 16 and are therefore correspondingly allowable.
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 ALIA SABUR whose telephone number is (571)270-7219. The examiner can normally be reached M-F 9:30-5:30.
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/ALIA SABUR/Primary Examiner, Art Unit 2812
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