DETAILED ACTION
Table of Contents
I. Notice of Pre-AIA or AIA Status 3
II. Claim Rejections - 35 USC § 103 3
A. Claims 1-14, 17, 18, and 22 are rejected under 35 U.S.C. 103 as being unpatentable over US 2024/0371935 (“Tang”) in view of US 2016/0126102 (“Chang”) and US 2023/0411496 (“Lin”), and as evidenced by US 2007/0111519 (“Lubomirsky”) for claim 3 only. 3
B. Claims 15-16 are rejected under 35 U.S.C. 103 as being unpatentable over Tang in view of Chang and Lin, as applied to claim 1 above, and further in view of US 2020/0091011 (“Khaderbad”). 16
III. Allowable Subject Matter 17
IV. Response to Arguments 18
Conclusion 19
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I. 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 .
II. 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 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 of this title, 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.
A. Claims 1-14, 17, 18, and 22 are rejected under 35 U.S.C. 103 as being unpatentable over US 2024/0371935 (“Tang”) in view of US 2016/0126102 (“Chang”) and US 2023/0411496 (“Lin”), and as evidenced by US 2007/0111519 (“Lubomirsky”) for claim 3 only.
Claim 1 reads,
1. (Currently Amended) A method of forming a contact structure on a semiconductor substrate, comprising:
[1a] removing material from surfaces of a plurality of contact structures formed in a feature formed in a surface of a substrate,
[1b] the plurality of contact structures comprising silicon (Si) or silicon germanium (SiGe),
[1c] wherein each of the plurality of contact structures are spaced apart in a first direction by a dielectric layer, and
[1d] the method of removing material comprises:
[1d-1] selectively forming a reaction product material over a surface of each of the plurality of contact structures; and
[1d-2] heating the substrate to a first temperature to remove the reaction product material from the surface of each of the plurality of contact structures;
[2] selectively forming a first metal layer on the surface of each of the plurality of contact structures;
[3a] forming a second metal layer on the first metal layer, wherein forming the second metal layer on the first metal layer comprises:
[3b] selectively depositing the second metal layer on the first metal layer by exposing a surface of the first metal layer to a fluorine-free metal containing precursor;
[4] forming a third metal layer on the second metal layer;
[5] filling the feature with a conductor material, wherein the conductor material comprises tungsten (W) or molybdenum (Mo); and
[6] depositing a capping layer on the conductor material.
With regard to claim 1, Tang discloses, generally in Figs. 19-25, 27, and 29,
1. (Currently Amended) A method of forming a contact structure on a semiconductor substrate, comprising:
[1a] removing material [i.e. “native oxide” formed on the upper surface of the Si or SiGe “etch stop layer 145” (¶¶ 46-49, 62—especially ¶ 48; Fig. 12; see explanation below)] from surfaces of a plurality of contact structures 448(148) [in Figs. 27, 29, and 11 (¶¶ 76, 78, 40-45); see explanation below)] formed in a feature 143 [i.e. “contact openings 143”; Fig. 19] formed in a surface of a substrate 101 [¶ 16],
[1b] the plurality of contact structures 448(148) comprising silicon (Si) or silicon germanium (SiGe) [¶ 44],
[1c] wherein each of the plurality of contact structures 448(148) are spaced apart in a first direction by a dielectric layer 144 [i.e. “dielectric spacers 144” (¶ 38)], and
[1d] the method of removing material [i.e. the “native oxide” formed on the upper surface of the Si or SiGe etch stop layer 145 (¶ 62)] comprises:
[1d-1]-[1d-2] … [not taught] …
[2] selectively forming a first metal layer 184(177) on the surface of each of the plurality of contact structures 448(148) [¶¶ 63-64; the selectivity shown in each of Figs. 20-21, 27, and 29];
[3a]-[3c] … [not taught] …
[4] … [not taught] …
[5] filling the feature with a conductor material [i.e. 486(186) in Figs. 27 and 25 (¶¶ 66-67, 76) and 686(186) in Figs. 29 and 25 (¶¶ 66-67, 78)], wherein the conductor material comprises tungsten (W) or molybdenum (Mo) [¶ 67: “In some embodiments, the S/D contacts 186 are formed of Co, W, Ru, or Mo.”]; and
[6] depositing a capping layer [486(192) in Figs. 27 and 25 and 692(192) in Figs. 29 and 25 (¶¶ 73, 76, 78)] on the conductor material 486(186), 686(186).
With regard to features [1a]-[1d] of claim 1, the “epitaxial bottom layer blocks 448” shown in each of Figs. 27 and 29 (¶¶ 76, 78) are formed in the same manner as the “epitaxial bottom layer 148” in the embodiment shown in Figs. 9-25 (¶ 5) particularly at Figs. 9-11, as explained at paragraphs [0005] and [0075]-[0078], noting the following:
The epitaxial bottom layer 348 may include the same material as the epitaxial bottom layer 148, and may be deposited using a conformal deposition technique, or any suitable deposition process in a similar fashion as discussed above with respect to FIG. 11. After the formation of the epitaxial bottom layer 348, an etch stop layer (e.g., etch stop layer 145) and a sacrificial layer (e.g., sacrificial layer 150) may be sequentially formed over the epitaxial bottom layer 348.
(Tang: ¶ 75; emphasis added)
[0076] FIG. 27 illustrates a cross-sectional side view of a semiconductor device structure 400, in accordance with some alternative embodiments. This embodiment is similar to the embodiment shown in FIG. 26 except that an epitaxial bottom layer is formed primarily on the first semiconductor layers 106, resulting in a plurality of epitaxial bottom layer blocks 448.
(Tang: ¶ 76; emphasis added)
FIG. 29 illustrates a cross-sectional side view of a semiconductor device structure 600, in accordance with some alternative embodiments. This embodiment is similar to the embodiment shown in FIG. 27 …
(Tang: ¶ 78; emphasis added)
Because the “epitaxial bottom layer blocks 448” are formed in the same manner as “epitaxial bottom layer 148” but for the being formed in blocks separated by the dielectric spacers 144, the rest of the overall contact structures shown in Figs. 27 and 29, including the silicide layer 184, and the contact structures 486 (in Fig. 27) and 686, 692 (in Fig. 29) are also formed by the processes explained in conjunction with the embodiment in Figs. 9-25, particular in Figs. 19-25.
With regard to features [1d]-[1d-2] of claim 1 and claims 2 and 3,
[1d] the method of removing material comprises:
[1d-1] selectively forming a reaction product material over a surface of each of the plurality of contact structures; and
[1d-2] heating the substrate to a first temperature to remove the reaction product material from the surface of each of the plurality of contact structures;
2. The method of claim 1, wherein the reaction product material will include a silica salt containing material.
3. The method of claim 2, wherein silica salt containing material comprises an ammonium hexafluorosilicate.
As explained above, the contacts 448 in Figs. 27 and 29 are the shared contact 148 in Figs. 9-25; therefore, the Si or SiGe etch stop layer 145 (¶¶ 46-49) would also have been applied to each of the “epitaxial bottom layer blocks 448” in each of Figs. 27 and 29, which would then also have been oxidized to form a “native oxide” (¶ 48) prior to forming the sacrificial layer 150, in order to gain a good etch profile when removing the sacrificial layer 150 to expose the etch stop layer 145 (¶ 48):
[0048] In some embodiments, the etch stop layer 145 is further subjected to an oxidation process to oxidize an outer portion of the etch stop layer 145. The oxidation process converts the outer portion of the etch stop layer 145 to a native oxide layer, which can enhance etching reaction at the surface of the etch stop layer 145. The native oxide layer helps the etch stop layer 145 with better etching profile control at a later stage when removing the subsequent sacrificial layer 150 for the S/D contact formation. In cases where the etch stop layer 145 is formed of silicon, germanium, or silicon germanium, the etch stop layer 145 may have the outer portion in the form of either (Si, Ge)O2 or germanium oxide (e.g., GeO2), and an inner portion containing silicon, germanium, or silicon germanium. The oxidation process may be thermal oxidation process, a rapid thermal oxidation (RTO) process, an in-situ stream generation (ISSG) process, or an enhanced in-situ stream generation (EISSG) process. …
(Tang: ¶ 48; emphasis added)
Although not discussed in Tang, in order to form the silicide layer 184 in the upper surface of the Si or SiGe etch stop layer 145 (Figs. 18-20; ¶¶ ), the “native oxide” (¶ 48) would necessarily have to be removed after removing the Si or SiGe sacrificial layer 150 (¶ 49) by “one or more etching processes, such as an anisotropic etching process. The one or more etching processes may be a plasma etching process employing etchants such as chlorine-containing gas, a bromine-containing gas, and/or a fluorine-containing gas” (¶ 62; Figs. 18-19).
Tang does not, however, explain how the native oxide is removed and therefore does not teach the claimed removal process in features [1d]-[1d-2] of claim 1 and claims 2 and 3.
Chang, like Tang, teaches a method of forming a S/D contact structure 74/80 to S/D regions 38 in a contact opening 60 (Chang: ¶ 27, 36, 39; Fig. 16) including forming a silicide layer 74 on the epitaxial S/D regions 38 (Chang: Fig. 12: ¶ 36). Also like Tang, Chang teaches that, after etching the contact opening 60, the epitaxial S/D regions have “native oxide” regions 64 formed on them (Chang: ¶ 28-29). Chang further teaches that a “pre-clean process” is performed to remove the native oxide (id.) in order to reduce contact resistance (Chang: ¶ 30).
The native-oxide-removing process is “process gas comprising NF3 and NH3, which process gas is also referred to as SiCoNi (a registered trade mark of Applied Materials, Inc.)” (Chang: ¶ 31)—which is the same pre-clean process as that disclosed in the Instant Application and claimed in features [1d]-[1d-2] of claim 1 and claims 2 and 3. In this regard, Chang explained that the SiCoNi process includes the following:
[1d] the method of removing material [i.e. native oxide 64 relative to epitaxial Si or SiGe S/D region 38 (Chang: ¶ 29)] comprises:
[1d-1] selectively forming a reaction product material 70 [i.e. NH4SiF6] over a surface of each of the plurality of contacts 38 [¶¶ 31-32]; and
[1d-2] heating the substrate to a first temperature [100 ℃ to 300 ℃] to remove the reaction product material 70 from the surface of each of the plurality of contacts 38 [¶¶ 33-34; Fig. 10];
2. (Original) The method of claim 1, wherein the reaction product material will include a silica salt containing material [i.e. NH4SiF6 (¶ 32: Eq. 1)].
3. (Original) The method of claim 2, wherein silica salt containing material comprises an ammonium hexafluorosilicate [i.e. NH4SiF6 (¶ 32: Eq. 1)].
That this is the SiCoNi process and that NH4SiF6 is ammonium hexafluorosilicate is evidenced by Lubomirsky—which is commonly assigned to the same assignee as is the Instant Application (at ¶¶ 203-216—especially ¶¶ 204 and 213-216).
Inasmuch as Tang merely fails to provide the details as to how the “native oxide” is removed from each of the Si or SiGe etch stop layers 145 on each of the epitaxially-grown Si or SiGe S/D contact blocks 448 after the Si or SiGe sacrificial layer 150, it would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, to use the SiCoNi process taught in Chang to remove said native oxide from said etch stop layers 145, because Chang teaches that the SiCoNi process removes native oxide from S/D region regions and thereby results in lower contact resistance (Chang: ¶ 30). (See MPEP 2143(I)(A), (C), and (E).)
With regard to features [3a]-[3c] and [4] of claim 1 and claims 5-11 and 22,
[3a] forming a second metal layer on the first metal layer, wherein forming the second metal layer on the first metal layer comprises
[3b] selectively depositing the second metal layer on the first metal layer, and
[3c] selectively forming the second metal layer comprises exposing the surface of the selectively formed first metal layer to a fluorine-free metal containing precursor to form the second metal layer;
[4] forming a third metal layer on the second metal layer;
5. (Original) The method of claim 1, wherein the fluorine-free metal containing precursor comprises tungsten and a halogen containing gas.
6. (Original) The method of claim 5, wherein the fluorine-free metal containing precursor is selected from a group consisting of tungsten pentachloride (WCl5), tungsten hexachloride (WCl6), tungsten pentabromide (WBr5), and tungsten hexabromide (WBr6).
7. (Original) The method of claim 1, wherein the fluorine-free metal containing precursor comprises molybdenum and a halogen containing gas.
8. (Original) The method of claim 7, wherein the fluorine-free metal containing precursor is selected from a group consisting of molybdenum pentachloride (MoCl5), molybdenum hexachloride (MoCl6), and molybdenum oxytetrachloride (MoOCl4).
9. (Original) The method of claim 8, wherein filling the feature with the conductor material comprises selectively forming the conductor material on the first metal layer, which comprises exposing the first metal layer to a fluorine-containing precursor.
10. (Original) The method of claim 9, wherein selectively forming the conductor material comprises exposing the second metal layer to a metal precursor that comprises molybdenum (Mo).
11. (Original) The method of claim 9, wherein selectively forming the conductor material comprises exposing the second metal layer to a metal precursor that comprises tungsten hexafluoride (WF6).
22. (New) The method of claim 1, wherein the third metal layer is formed by a conformal layer deposition process.
Tang does not provide the details of the CVD, PVD, or ALD process used to form the (metal S/D contact 686)/(contact metal layer 692) in Fig. 29 or metal contact 486 in Fig. 27, which is equivalent to, e.g., the (metal S/D contact 186)/(contact metal layer 192) in Fig. 25 [¶ 73]).
Lin, like Tang, teaches a method of forming a S/D contact structure 910/920/930 to S/D regions 356 in a contact opening 820 (Lin: ¶¶ 43-80; Figs. 9A-9E) that may be applicable to gate-all-around (GAA) transistors (Lin: ¶ 13) as in Tang, including selectively forming a silicide layer 910 on the epitaxial S/D regions 356 (Lin: Fig. 9B: ¶ 44) and a contact metal fill 930 that may be W or Mo (Lin: ¶ 75; Fig. 9D).
Lin further teaches that, before the metal fill 930 is formed, a “metal capping layer 920” is selectively deposited on the metal silicide 910 that is made of either W or Mo, using fluorine-free precursors, e.g. MoClx or WClx (Lin: ¶ 46)—as required by claims 5-8—in order to provide a nitride-free or nitrogen-free surface on the silicide, which reduces contact resistance relative to a metal nitride and aids in the bottom-up filling of the contact opening with the W or Mo contact fill 930 (Lin: ¶ 45) that is selectively deposited on the metal capping layer 920 using fluorine-containing precursors (Lin: ¶¶ 75, 78, 80)—as further required by claims 9-11. By “selectively deposited” with regard to the W or Mo contact fill 930 is meant the following:
[0076] In some embodiments, parameters of the deposition process 950 for the conductive material 930 are tuned, such that the conductive material 930 is deposited in the openings 810, 820 and 830 in a non-conformal bottom-up manner from the metal capping layer 920. In some embodiments, the parameters of the deposition process 950 are tuned, such that a deposition rate of the conductive material 930 on materials of the first ILD 362 and the second ILD 780 is reduced or suppressed compared to a deposition rate of the conductive material 930 on a material of the metal capping layer 920. In this manner, the conductive material 930 is selectively formed on the metal capping layer 920 and fills the openings 810, 820 and 830 in a bottom-up manner, which allows for reducing or avoiding the formation of voids in the conductive material 930.
(Lin: ¶ 76; emphasis added)
Lin further teaches that the selective bottom-up metal fill process for forming the W or Mo contact fill 930 can be atomic layer deposition (ALD) (¶ 78), which builds up one atomic layer at a time. As such, the first atomic layer of W or Mo formed by ALD reads on “third metal layer”—as required by feature [4] of claim 1. In addition ALD is a conformal process, as required by new claim 22. Moreover, use of ALD for the bulk metal contact 186 in the embodiment shown in Figs. 20-22 is consistent with Tang (Tang: ¶ 67) even though, as stated above, Tang does not indicate the bulk metal fill process used for the embodiments shown in Figs. 27 and 29.
Inasmuch as Tang is merely silent to the process by which the contact fill 486(186), 686 in the embodiments shown in Figs. 27 and 29, respectively, is formed, it would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, to use the process taught in Lin, including (1) selectively forming a nitrogen-free Mo or W capping layer, i.e. the claimed “second metal layer” on each of the silicide layers 184 on each of the contact blocks 448 of Tang, using fluorine-free precursors, e.g. MoClx or WClx (Lin: ¶ 46) in order to reduce contact resistance and aid the bottom-up filling of the Mo or W contact fill 486, 686, as taught in Lin (Lin: ¶ 45), and (2) selectively forming the Mo or W contact fill 486, 686 on the metal capping layer using the fluorine-containing precursors using ALD (Lin: ¶¶ 78, 80), in order to use a bottom-up fill process that reduces void formation and thereby reduces resistance of the contact plugs, as taught in Lin (Lin: ¶ 76). As such, Lin may be seen as either filling in the missing descriptive information on the contact fill not discussed in Tang or may be seen as an improvement to Tang in this aspect. (See MPEP 2143.)
Again, by using the ALD process of Lin to form the bulk fill 486, 686 of Tang, includes “forming a third metal layer on the second metal layer”, because the first atomic layer that selectively deposits on the capping layer (supra) is a separate distinct layer from the remaining atomic layer subsequently deposited.
In the alternative, two or more atomic layers may be taken as the claimed “third metal layer” until the portions selectively growing from the contacts 448 coalesce to form the Mo or W metal contact fill 486, 686. This is consistent with the Instant Application, which forms each of the second metal layer 404, the third metal layer 409, and the “conductor material” filling the feature from the same metal:
[0053] In FIG. 4C, the second metal layer 404 shown is formed by a second metal deposition process on top of the metal silicide layer 402. In one or more embodiments, the metal utilized for the second metal deposition process may comprise a fluorine-free tungsten (FFW) containing precursor. In one or more embodiments, the FFW containing precursor may comprise tungsten pentachloride (WCl5), tungsten hexachloride (WCl6), … In yet other embodiments, the metal utilized for the second metal deposition process may comprise molybdenum (Mo) that is formed by use of molybdenum containing precursor such as molybdenum pentachloride (MoCl5), molybdenum hexachloride (MoCl6), or molybdenum oxytetrachloride (MoOCl4)
(Instant Specification: ¶ 53; emphasis added)
the third metal layer 409 comprises W or Mo
(Instant Specification: ¶ 72; emphasis added)
[0074] In FIG. 4H, the opening 401 is shown filled with a conductor material 406 formed by a fourth metal deposition process on top of the third metal layer 409. In one or more embodiments, the conductor material 406 utilized for the fourth metal deposition process may comprise a precursor that comprises tungsten hexafluoride (WF6). In yet other embodiments, the conductor material utilized for the fourth metal deposition process may comprise molybdenum (Mo), which can, for example, be deposited by use of a molybdenum pentachloride (MoCl5) or molybdenum hexafluoride (MoF6) precursor.
(Instant Specification: ¶ 74; emphasis added)
With regard to feature [6] of claim 1, Tang shows the “contact metal layer 692”, i.e. the claimed “capping metal” in the embodiment in Fig. 29, it is not shown in the embodiment in Fig. 27. However, Tang explains that the contact metal layer 192, 692 reduces the overall contact resistance of the S/D contact (¶ 73).
It would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, to include the contact metal layer 192 in the embodiment shown in Fig. 27 in order to reduce the contact resistance, as suggested in Tang (¶ 73).
This is all of the limitations of claims 1-3, 5-11, and 22.
With regard to claim 4, each of Tang and Lin further discloses,
4. (Original) The method of claim 3, wherein the first metal layer 184(177) comprises a metal silicide layer that comprises titanium [Tang: ¶¶ 63-64; Lin: (see discussion under claim 1)].
Claims 12, 13, and 17 read,
12. (Currently Amended) The method of claim 1, wherein the first metal layer formed on the exposed surfaces of each of the plurality of contact structures has a thickness of greater than or equal to about three nanometers.
13. (Currently Amended) The method of claim 12, wherein the first metal layer on the exposed surfaces of each of the plurality of contact structures comprises a first metal layer target thickness determined by a corresponding Schottky Barrier Height (SBH).
17. (Currently Amended) The method of claim 12, wherein the first metal layer on the exposed surfaces of each of the plurality of contact structures comprises a first metal layer target thickness determined by a corresponding gate contact structure resistance (Rc).
Tang does not teach the thickness of the metal silicide 184, i.e. the claimed “first metal layer”.
Lin further teaches that the metal silicide 910 is formed to be from about 1 nm to about 10 nm (Lin: ¶ 43).
It would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, to make the thickness of the silicide 184 in Tang to be from 1 nm to 10 nm, e.g. any of 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, and 10 nm, because Lin teaches that these thicknesses are suitable for reducing the contact resistance.
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 In re Wertheim, 541 F.2d 257, 191 USPQ 90 (CCPA 1976); MPEP 2144.05(I)). In such a situation, Applicant must show that the particular ranges are critical, generally by showing that the claimed range achieves unexpected results relative to the prior art range. See In re Woodruff, 919 F.2d 1575, 16 USPQ2d 1934 (Fed. Cir. 1990). (See MPEP 2144.05(III)(A); emphasis added.)
Because the thickness can be greater than 3 nm, it is held, absent evidence to the contrary, that the thickness of the silicide 184 is inherently “determined by a corresponding Schottky Barrier Height (SBH)” and/or “a corresponding gate contact structure resistance (Rc)”, as the purpose of the silicide is to reduce the contact resistance, as is exceedingly well known in the art. As such, the burden of proof is shifted to Applicant to prove the contrary. (See MPEP 2112(I)-(V).)
Claim 14 reads,
14. (Currently Amended) The method of claim 1, wherein selectively depositing the second metal layer on an outer surface of the first metal layer on the exposed surfaces of each of the plurality of contact structures comprises a second metal layer thickness greater than or equal to about three nanometers.
As explained above under claim 1, the second metal layer, i.e. the metal capping layer 920 of Lin 920 is used on the silicide layer 184 of Tang. Lin further teaches that the thickness of the metal capping layer 920 is from 1 nm to 20 nm.
It would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, to make the thickness of the metal capping layer 920 of Lin used in Tang to be from 1 nm to 20 nm, e.g. 3 nm through 20 nm, because Lin teaches that these thicknesses are suitable for it its intended purpose (supra).
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 In re Wertheim, 541 F.2d 257, 191 USPQ 90 (CCPA 1976); MPEP 2144.05(I)). In such a situation, Applicant must show that the particular ranges are critical, generally by showing that the claimed range achieves unexpected results relative to the prior art range. See In re Woodruff, 919 F.2d 1575, 16 USPQ2d 1934 (Fed. Cir. 1990). (See MPEP 2144.05(III)(A); emphasis added.)
Claim 18 reads,
18. (Original) The method of claim 1, wherein the second metal layer [i.e. the metal capping layer 920 of Mo or W of Lin used in Tang] provides an Oxygen (O) barrier, or a Fluorine (F) barrier, or both an O and F barrier.
Inasmuch as Lin uses the same metals, i.e. W or Mo, as used in the Instant Application for the second metal layer formed using F-free precursors, and then formed the fill using a F-containing Mo or F precursor, it is held, absent evidence to the contrary, that the second metal layer of Tang/Lin is a barrier to each of F and O, as evidenced by the admissions in the Instant Application. As such, the burden of proof is shifted to Applicant to prove the contrary. (See MPEP 2112(I)-(V).)
B. Claims 15-16 are rejected under 35 U.S.C. 103 as being unpatentable over Tang in view of Chang and Lin, as applied to claim 1 above, and further in view of US 2020/0091011 (“Khaderbad”).
Claims 15 and 16 read,
15. (Currently Amended) The method of claim 1, wherein selectively forming a first metal layer on the plurality of contacts comprises introducing a hydrogen-containing reducer and a first metal containing precursor to a contact surface such that a first metal layer forms on top of the contact surface that comprises silicon or silicon germanium.
16. (Original) The method of claim 15, wherein the hydrogen-containing reducer includes molecular hydrogen (H2).
The prior art of Tang in view of Chang and Lin, as explained above, teaches each of the features of claim 1.
Tang further discloses that the first metal layer 177 from which the silicide layer 184 is formed may be selectively formed by, e.g. CVD or ALD (Tang: ¶ 63; Figs. 20-21), which necessarily requires a metal-containing precursor but does not provide the process conditions and does not consequently disclose claimed “hydrogen-containing reducer” of H2 as required by of claims 15 and 16.
Lin also teaches that the silicide 910 can be selectively formed on the exposed S/D regions 356 using CVD or ALD (Lin: ¶ 44) but does not indicate the metal precursor or the deposition conditions and does not consequently disclose claimed “hydrogen-containing reducer” of H2 as required by of claims 15 and 16.
Khaderbad, like each of Tang and Lin, selectively deposits a silicide layer 360, e.g. titanium silicide (TiSix), on exposed epitaxial layer 330A of a source/drain regions 220 (Khaderbad: ¶ 39; Fig. 4). Khaderbad further teaches that the selective deposition used a precursor, e.g. TiCl4, and hydrogen (H2) (id.).
It would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, to use, e.g., TiCl4, and hydrogen (H2) to deposit the silicide layer 184 in Tang using the process in Khaderbad because Tang desires selective deposition of the metal silicide layer 184, as shown in Figs. 20-21, 27 and 29 but fails to provide the deposition details such that one having ordinary skill in the art would use known processes suitable for selectively depositing metal silicide on epitaxial regions of the S/D contact regions, such as the selective deposition process taught in Khaderbad.
This is all of the limitations of claims 15 and 16.
III. Allowable Subject Matter
Claims 20 and 21 are 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:
20. (Currently Amended) The method of claim 1, wherein forming the third metal layer on the second metal layer comprises sputtering a metal containing material on the second metal layer.
21. (New) The method of claim 1, wherein forming the third metal layer on the second metal layer comprises depositing the third metal layer by a physical vapor deposition (PVD) process.
The prior art does not reasonably teach or suggest—in the context of the claims—forming the third metal layer using a PVD process, such as sputtering a metal containing material. As explained above, the bulk fill is formed by ALD, which is the process of forming both the claimed “third metal layer on the second metal layer”, i.e. the first atomic layer or collection of atomic layers of the bulk fill using ALD in the process steps of Lin used in Tang (supra). As such, using a PVD process, e.g. sputtering, to form a third metal layer separate from the bulk fill formed using ALD is not taught or suggested in the prior art of Tang/Lin.
IV. Response to Arguments
Applicant’s arguments filed 06/22/2026 have been fully considered but they are not persuasive.
Applicant traverses the rejection of claim 1 over Tang in view of Chang and Lin, asserting that Lin fails to disclose the claimed “third metal layer” on the second metal layer (Remarks: pp. 7-8). Examiner respectfully disagrees because, as stated in the Non-Final Rejection, paragraph [0078] of Lin was also cited and teaches that ALD may be used to deposit the fill layer 930 (Non-Final Rejection mailed 02/20/2026, each of pp. 13-14). As is exceedingly well known in the art, ALD deposits one atomic layer at a time which means that at least the very first atomic layer that is selectively deposited on the underlying second metal layer, i.e. the “metal capping layer 920” (Lin: ¶¶ 45-46), or however, many atomic layers that builds up some thickness, reads on the claimed “third metal layer”, as explained in the rejection (supra).
Applicant further argues,
Applicant submits that the third metal layer is not merely an initial growth region of the conductor fill itself, but rather a separately formed intermediate metal layer positioned between the second metal layer and the conductor material. Accordingly, amended claim 1 requires both forming a third metal layer on the second metal layer and filling the feature with a conductor material.
(Remarks: p. 8)
While Applicant asserts that the “third layer” is a separate metal layer between the second metal layer and the conductor material, i.e. the bulk fill, as explained in the rejection, the Instant Application indicates that each of the second third, and “conductor material” that is the bulk fill. Merely calling some portion of the overall bulk fill a “third metal layer” does not distinguish it from the second metal layer and the conductor material when all made of the same metal (supra). As such, without more, Examiner respectfully maintains that—as currently drafted—there is no distinction. And even so, as explained above, the ALD of Lin, used to form the bulk fill necessarily includes the “third metal layer” as the first atomic layer on the metal capping layer 920. As also clarified under the section entitled, “Allowable Subject Matter”, the specific processes of depositing the third metal layer claimed in claims 20 and 21 distinguishes over the prior art.
The remaining of Applicant’s arguments are premised on the alleged deficiencies in the combination of Tang with Lin (Remarks: pp. 8-9). As such, Examiner respectfully disagrees with these arguments for the same reasons as explained above.
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 extension fee 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 date of this final action.
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Signed,
/ERIK KIELIN/
Primary Examiner, Art Unit 2814
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