DETAILED ACTION
Information Disclosure Statement
The information disclosure statement (IDS) submitted on 04/10/2025 is in compliance with the provisions of 37 CFR 1.97. Accordingly, the information disclosure statement is being considered by the examiner.
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 1-8, 11, 12, and 15 are rejected under 35 U.S.C. 103 as being unpatentable over Cheng et al. (US 20200135475 A1), hereinafter “Cheng,” in view of Hempel et al. (US 20120315749 A1), hereinafter “Hempel.”
Re: Independent claim 1, Cheng discloses a method of forming a semiconductor device (See Figs. 1A and 1B), comprising:
forming a high-k gate dielectric layer over a channel region of a substrate (Fig. 1A, step 108 – form gate dielectric on interfacial layer; Fig. 6: dielectric layer 504; ¶0029: a gate dielectric layer 504 is formed on the interfacial layer 502 within the gate recess 402; ¶0030: Suitable materials for the gate dielectric layer 504 are… high-k dielectric materials such as HfO.sub.2);
depositing a work function metal layer over the high-k gate dielectric layer (Fig. 1B, step 124; ¶0053: Referring to block 124 of FIG. 1B and referring to FIGS. 12-14, one or more work function layers are formed… work function materials include TiN, TaN… TiAlN);
…
depositing a silicon cap layer over the TiN cap (¶0037: In some embodiments, the second capping layer 604 includes amorphous silicon.; ¶0038: The deposition process may be configured to produce a second capping layer 604, which may be TiN.; ¶0068: a second capping layer is formed on the first capping layer… In some such embodiments, the first capping layer includes a metal nitride);
depositing a conductive glue layer over the silicon cap layer (¶0057: a glue layer 1206 is formed on the fourth capping layer 1204… The glue layer 1206 may contain any suitable material selected to promote adhesion between layers and may include metals, i.e., conductive, metal nitrides, and/or metal silicon nitrides, and in an example, the glue layer 1206 includes tungsten.); and
depositing a gate fill metal layer over the conductive glue layer to form a gate structure (Fig. 14: electrode fill 1208, i.e., gate fill; ¶0058: Referring to block 130 of FIG. 1B and to referring still to FIG. 14, an electrode fill 1208 is formed within the gate recesses 402 on the glue layer 1206.).
While Cheng discloses multiple layers including TiN cap layers and performing an anneal wherein the first capping layer includes nitrogen as a source for passivation where nitrogen is diffused into the high-k dielectric material to compensate for oxygen vacancies in the high-k dielectric material (See Cheng, ¶0034), Cheng does not specifically disclose forming a titanium nitride (TiN) cap over the work function metal layer, wherein the TiN cap includes one or more oxygen regions;
In a similar field of endeavor, Hempel discloses forming a titanium nitride (TiN) cap over the work function metal layer, wherein the TiN cap includes one or more oxygen regions (¶0039: first sub-layer 215a by forming two separate cap layer portions, as well as to perform additional intermediate treatment and processing steps so as to adjust the oxygen and nitrogen content distribution within the first sub-layer 215a.; ¶0040: oxygen atoms diffuse into the first metal gate cap layer 215a-1 and along the grain boundaries toward the interface 210i, thereby increasing the overall oxygen content of the first metal gate cap layer 215a-1.).
Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date to have modified a TiN deposition process by exposing said material to an environment having oxygen in order to achieve desired device operating characteristics and threshold voltage (Vt) (See Hempel, ¶0038).
Re: claim 2, the combination of Cheng and Hempel discloses the method of claim 1.
Hempel also discloses further comprising: performing an annealing process to the gate structure such that oxygen atoms in the TiN cap diffuses into the high-k gate dielectric layer (¶0039: first sub-layer 215a by forming two separate cap layer portions, as well as to perform additional intermediate treatment and processing steps so as to adjust the oxygen and nitrogen content distribution within the first sub-layer 215a.; ¶0040: oxygen atoms diffuse into the first metal gate cap layer 215a-1 and along the grain boundaries toward the interface 210i, thereby increasing the overall oxygen content of the first metal gate cap layer 215a-1.; ¶0043: During the thermal treatment 235, at least some of the oxygen atoms present in the first sub-layer 215a--including at least some of the oxygen atoms previously diffused into the first metal gate cap layer 215a-1 during the oxygen diffusion process 234--may be driven toward the interface 210i and the layer of high-k dielectric material 214, thereby raising the oxygen content in the lower portion of the first sub-layer 215a (i.e., in the first metal gate cap layer 215a-1) and around the interface 210i.).
Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date to have modified a TiN deposition process by exposing said material to an environment having oxygen in order to achieve desired device operating characteristics and threshold voltage (Vt) (See Hempel, ¶0038).
Re: claim 3, the combination of Cheng and Hempel discloses the method of claim 2.
Cheng further discloses wherein during and after the performing of the annealing process, the silicon cap layer functions to prevent oxygen atoms from diffusing into the TiN cap (¶0037: In some embodiments, the second capping layer 604 includes amorphous silicon.; ¶0044: In some embodiments, the third capping layer 702 is substantially similar to the second capping layer 604 and includes amorphous silicon.; ¶0045: Because of the presence of the second capping layer 604, the other materials of the gate structure may no longer need protection from oxygen.; In other words, Cheng discloses a capping layer which includes silicon, layered on top of the TiN layers which prevents oxygen from being absorbed into the lower layers from a region above the silicon cap.).
Re: claim 4, the combination of Cheng and Hempel discloses the method of claim 1.
Cheng further discloses wherein the forming of the TiN cap includes:
depositing a first TiN capping layer over the work function metal layer (¶0034: The first capping layer 602 may include any suitable protective material including metals (e.g., W, Al, Ta, Ti, Ni, Cu, Co, etc.), metal nitrides, and/or metal silicon nitrides. In various such embodiments, the first capping layer 602 includes TiSiN and/or TiN.];
…
depositing a second TiN capping layer over the first TiN capping layer (¶0037: The second capping layer 604 may include any suitable protective material including metals, semiconductors, and nitrides thereof. The second capping layer 604 may be the same or different in composition from the first capping layer 602, i.e., TiN).
However, Cheng does not disclose performing an oxygen treatment to the first TiN capping layer; and
Hempel further discloses performing an oxygen treatment to the first TiN capping layer (¶0039: first sub-layer 215a by forming two separate cap layer portions, as well as to perform additional intermediate treatment and processing steps so as to adjust the oxygen and nitrogen content distribution within the first sub-layer 215a.; ¶0040: oxygen atoms diffuse into the first metal gate cap layer 215a-1 and along the grain boundaries toward the interface 210i, thereby increasing the overall oxygen content of the first metal gate cap layer 215a-1.).
Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date to have modified a TiN deposition process by exposing said material to an environment having oxygen in order to achieve desired device operating characteristics and threshold voltage (Vt) (See Hempel, ¶0038).
Re: claim 5, the combination of Cheng and Hempel discloses the method of claim 4.
Cheng further discloses wherein the first TiN capping layer is deposited in a vacuum sealed physical vapor deposition (PVD) chamber (¶0035: The first capping layer 602 may be deposited via ALD, PEALD, CVD, PE CVD, Physical Vapor Deposition (PVD))
However, Cheng does not specifically disclose wherein the oxygen treatment includes:
removing a workpiece having the first TiN capping layer from the PVD chamber; and
exposing the first TiN capping layer to an environment outside of the PVD chamber.
In a similar field of endeavor, Hempel discloses wherein the oxygen treatment includes:
removing a workpiece having the first TiN capping layer from the PVD chamber (¶0040: In some illustrative embodiments, the oxygen diffusion process 234 may be performed under substantially ambient atmospheric conditions. For example, the oxygen diffusion process may be performed under typical clean room conditions, wherein the stoichiometry of the clean room atmosphere comprises an oxygen content ranging from 20-22% by weight, and wherein the temperature may be maintained between 18.degree. C. and 22.degree. C. In other words, the semiconductor device may be removed from the PVD chamber and placed in a clean room for exposure to ambient atmospheric conditions.); and
exposing the first TiN capping layer to an environment outside of the PVD chamber (¶0040: FIG. 2c shows the illustrative semiconductor device 200 of FIG. 2b in a further manufacturing stage, wherein the transistor element 250 is exposed to an oxygen diffusion process 234. During the oxygen diffusion process 234, oxygen atoms diffuse into the first metal gate cap layer 215a-1 and along the grain boundaries toward the interface 210i, thereby increasing the overall oxygen content of the first metal gate cap layer 215a-1.).
Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date to have modified a TiN deposition process by exposing said material to an environment having oxygen in order to achieve desired device operating characteristics and threshold voltage (Vt) (See Hempel, ¶0038).
Re: claim 6, the combination of Cheng and Hempel discloses the method of claim 5.
Hempel further discloses wherein the environment is air at room temperature (¶0040: In some illustrative embodiments, the oxygen diffusion process 234 may be performed under substantially ambient atmospheric conditions. For example, the oxygen diffusion process may be performed under typical clean room conditions, wherein the stoichiometry of the clean room atmosphere comprises an oxygen content ranging from 20-22% by weight, and wherein the temperature may be maintained between 18.degree. C. and 22.degree.), and the first TiN capping layer is exposed to the environment for at least 3 hours (¶0040: 18-22° C, i.e., room temperature, … the semiconductor device 200 may be exposed to the above-described clean room conditions for more than approximately 20 hours. In at least some embodiments, the semiconductor device 200 may be exposed to the above-described clean room conditions for approximately 24 hours, i.e., at least 3 hours).
Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date to have modified a TiN deposition process by exposing said material to an environment having oxygen in order to achieve desired device operating characteristics and threshold voltage (Vt) (See Hempel, ¶0038).
Re: claim 7, the combination of Cheng and Hempel discloses the method of claim 5.
Hempel further discloses wherein the environment is air at a temperature greater than 30° C., and the first TiN capping layer is exposed to the environment for less than 2 hours (¶0041: For example, in some embodiments, the stoichiometry of the clean room atmosphere may be maintained substantially as described above—i.e., with an oxygen content of approximately 20-22%—however, the exposure temperature may be raised to approximately 200° C. or less, and the exposure time may decreased to approximately 60 minutes or less. In one illustrative embodiments, the oxygen diffusion process 234 may be performed in an atmosphere comprising approximately 21% by weight, at a temperature of approximately 150° C., and for a time of approximately 30 minutes, i.e., less than 2 hours.).
Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date to have modified a TiN deposition process by exposing said material to an environment having oxygen in order to achieve desired device operating characteristics and threshold voltage (Vt) (See Hempel, ¶0038).
Re: claim 8, the combination of Cheng and Hempel discloses the method of claim 5.
Hempel further discloses wherein after the exposing, the workpiece is placed back into the PVD chamber, and the second TiN capping layer is deposited over the first TiN capping layer in the PVD chamber (¶0042: After completion of the oxygen diffusion process 234, the second of the two separate cap layer portions comprising the sub-layer 215a may be formed above the first metal gate cap layer 215a-1--i.e., the first of the two separate cap layer portions comprising the sub-layer 215a. As shown in FIG. 2d, a second metal gate cap layer 215a-2 may be formed above the first metal gate cap layer 215a-1 … In some embodiments, the second metal gate cap layer 215a-2 may be formed above the first metal gate cap layer 215a-1 by performing an appropriate conformal deposition process 233c, such as a PVD and/or ALD process.).
Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date to have modified a TiN deposition process by exposing said material to an environment having oxygen in order to achieve desired device operating characteristics and threshold voltage (Vt) (See Hempel, ¶0038).
Re: Independent claim 11, Cheng discloses a method of forming a semiconductor device (See Fig. 1A), comprising:
forming a high-k gate dielectric layer over a channel region of a substrate (Fig. 1A, step 108 – form gate dielectric on interfacial layer; Fig. 6: dielectric layer 504; ¶0029: a gate dielectric layer 504 is formed on the interfacial layer 502 within the gate recess 402; ¶0030: Suitable materials for the gate dielectric layer 504 are… high-k dielectric materials such as HfO.sub.2);
depositing a work function metal layer over the high-k gate dielectric layer (Fig. 1B, step 124; ¶0053: Referring to block 124 of FIG. 1B and referring to FIGS. 12-14, one or more work function layers are formed… work function materials include TiN, TaN… TiAlN);
depositing a first titanium nitride (TiN) capping layer over the work function metal layer (¶0034: The first capping layer 602 may include any suitable protective material including metals (e.g., W, Al, Ta, Ti, Ni, Cu, Co, etc.), metal nitrides, and/or metal silicon nitrides. In various such embodiments, the first capping layer 602 includes TiSiN and/or TiN.);
…
depositing a second TiN capping layer over the first TiN capping layer to form a TiN cap (¶0037: The second capping layer 604 may include any suitable protective material including metals, semiconductors, and nitrides thereof. The second capping layer 604 may be the same or different in composition from the first capping layer 602, i.e., TiN);
depositing a silicon cap layer over the TiN cap (¶0037: In some embodiments, the second capping layer 604 includes amorphous silicon.; ¶0038: The deposition process may be configured to produce a second capping layer 604, which may be TiN.; ¶0068: a second capping layer is formed on the first capping layer… In some such embodiments, the first capping layer includes a metal nitride);
depositing a conductive glue layer over the silicon cap layer (¶0057: a glue layer 1206 is formed on the fourth capping layer 1204… The glue layer 1206 may contain any suitable material selected to promote adhesion between layers and may include metals, i.e., conductive, metal nitrides, and/or metal silicon nitrides, and in an example, the glue layer 1206 includes tungsten.); and
depositing a gate fill metal layer over the conductive glue layer to form a gate structure (Fig. 14: electrode fill 1208, i.e., gate fill; ¶0058: Referring to block 130 of FIG. 1B and to referring still to FIG. 14, an electrode fill 1208 is formed within the gate recesses 402 on the glue layer 1206.).
While Cheng discloses multiple layers including TiN cap layers and performing an anneal wherein the first capping layer includes nitrogen as a source for passivation where nitrogen is diffused into the high-k dielectric material to compensate for oxygen vacancies in the high-k dielectric material (See Cheng, ¶0034), Cheng does not specifically disclose performing an oxygen treatment to the first TiN capping layer;
In a similar field of endeavor, Hempel discloses performing an oxygen treatment to the first TiN capping layer (¶0039: first sub-layer 215a by forming two separate cap layer portions, as well as to perform additional intermediate treatment and processing steps so as to adjust the oxygen and nitrogen content distribution within the first sub-layer 215a.; ¶0040: oxygen atoms diffuse into the first metal gate cap layer 215a-1 and along the grain boundaries toward the interface 210i, thereby increasing the overall oxygen content of the first metal gate cap layer 215a-1.);
Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date to have modified a TiN deposition process by exposing said material to an environment having oxygen in order to achieve desired device operating characteristics and threshold voltage (Vt) (See Hempel, ¶0038).
Re: claim 12, the combination of Cheng and Hempel disclose the method of claim 11.
Cheng further discloses wherein before the depositing the work function metal layer, further comprising:
depositing a sacrificial capping layer over the high-k gate dielectric layer (Fig. 1A, Steps 110 and 112 deposit capping layers over the high-k dielectric layer which are later removed as shown in Fig. 1B, step 120);
performing a first annealing process to the sacrificial capping layer and the high-k gate dielectric layer (Fig. 1A, step 114 – post metal annealing after capping of the high-k gate dielectric layer); and
removing the sacrificial capping layer (Fig. 1B, step 120), wherein after the depositing of the gate fill metal layer (Fig. 1A, step 108 followed by Fig. 1B, step 120; ¶0065: In some such embodiments, the second capping layer includes a material from a group consisting of: silicon and aluminum. In some such embodiments, the annealing process is a first annealing process, and the method further includes forming a third capping layer on the second capping layer within the gate trench, and performing a second annealing process on the workpiece that is configured to draw oxygen from the interfacial layer.), further comprising:
While Cheng discloses multiple layers including TiN cap layers and performing a post cap anneal process wherein the first capping layer includes nitrogen as a source for passivation where nitrogen is diffused into the high-k dielectric material to compensate for oxygen vacancies in the high-k dielectric material (See Cheng, ¶0034), Cheng does not specifically disclose performing a second annealing process to the gate structure such that oxygen atoms in the TiN cap diffuses into the high-k gate dielectric layer.
In a similar field of endeavor, Hempel discloses performing a second annealing process to the gate structure such that oxygen atoms in the TiN cap diffuses into the high-k gate dielectric layer (¶0039: first sub-layer 215a by forming two separate cap layer portions, as well as to perform additional intermediate treatment and processing steps so as to adjust the oxygen and nitrogen content distribution within the first sub-layer 215a.; ¶0040: oxygen atoms diffuse into the first metal gate cap layer 215a-1 and along the grain boundaries toward the interface 210i, thereby increasing the overall oxygen content of the first metal gate cap layer 215a-1.; ¶0043: During the thermal treatment 235, at least some of the oxygen atoms present in the first sub-layer 215a--including at least some of the oxygen atoms previously diffused into the first metal gate cap layer 215a-1 during the oxygen diffusion process 234--may be driven toward the interface 210i and the layer of high-k dielectric material 214, thereby raising the oxygen content in the lower portion of the first sub-layer 215a (i.e., in the first metal gate cap layer 215a-1) and around the interface 210i.; In other words, during the thermal treatment 235… oxygen atoms… may be driven toward… the layer of high-k dielectric material 214.).
Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date to have modified a TiN deposition process by exposing said material to an environment having oxygen in order to achieve desired device operating characteristics and threshold voltage (Vt) (See Hempel, ¶0038).
Re: Claim 15, the combination of Cheng and Hempel discloses the method of claim 11.
Hempel further discloses wherein the performing of the oxygen treatment includes exposing the first TiN capping layer to an environment outside of a vacuum chamber (¶0040: In some illustrative embodiments, the oxygen diffusion process 234 may be performed under substantially ambient atmospheric conditions. For example, the oxygen diffusion process may be performed under typical clean room conditions, wherein the stoichiometry of the clean room atmosphere comprises an oxygen content ranging from 20-22% by weight, and wherein the temperature may be maintained between 18.degree. C. and 22.degree. C.).
Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date to have modified a TiN deposition process by exposing said material to an environment having oxygen in order to achieve desired device operating characteristics and threshold voltage (Vt) (See Hempel, ¶0038).
Claims 9-10 are rejected under 35 U.S.C. 103 as being unpatentable over Cheng et al. (US 20200135475 A1) in view of Hempel et al. (US 201203 15749 A1) and Sumi et al. (US 5763948), hereinafter “Sumi.”
Re: Claim 9, the combination of Cheng and Hempel discloses the method of claim 4.
However, the combination of Cheng and Hempel do not seem to specifically disclose wherein the first TiN capping layer is deposited such that a top surface of the first TiN capping layer has a rough surface.
In a similar field of endeavor, Sumi discloses wherein the first TiN capping layer is deposited such that a top surface of the first TiN capping layer has a rough surface (col. 4, lns. 17-26: The aforesaid TiON film can be formed by forming, by reactive sputtering, the aforesaid TiN film with a ratio of the flow rates of the nitrogen gas with respect to the inert gas of 1.0 to 0.125, and then changing the ratio of the flow rates of the nitrogen gas with respect to the inert gas to the larger side to form a rough TiN film, then exposing this rough TiN film to the atmosphere or a low vacuum atmosphere having a divided pressure of oxygen of 0.1 Pa or more so as to change the rough TiN film to a TiON film.; col. 8, lns. 4-9: By ejecting the semiconductor substrate 22 from the sputtering chamber of the apparatus into the atmosphere, oxygen is stacked on the rough TiN surface to form a TiON film 48. In the present embodiment, the barrier metal has a double structure, so the barrier property is improved.).
Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date to have modified the process to include the steps disclosed in Sumi in order to achieve an improved barrier property (See Sumi, col. 8, lns. 6-9).
Re: Claim 10, the combination of Cheng, Hempel, and Sumi discloses the method of claim 9.
Sumi further discloses wherein the rough surface is formed by depositing a lower portion of the first TiN capping layer at a first deposition rate, depositing an upper portion of the first TiN capping layer at a second deposition rate, and the second deposition rate is greater than the first deposition rate (col. 4, lns. 6-26: When continuously forming the aforesaid first TiN film and second TiN film by the reactive sputtering, preferably the ratio of the flow rate of the nitrogen gas with respect to the inert gas is changed. Preferably, the ratio of the flow rates of the nitrogen gas with respect to the inert gas at the time of formation of the aforesaid first TiN film is controlled to 0.7 or less, more preferably 0.5 or less, i.e., first rate, and the ratio of the flow rates of the nitrogen gas with respect to the inert gas at the time of formation of the aforesaid second TiN film is controlled to 0.75 or more, more preferably 1.0 or more, i.e., second rate greater than first rate. The aforesaid TiON film can be formed by forming, by reactive sputtering, the aforesaid TiN film with a ratio of the flow rates of the nitrogen gas with respect to the inert gas of 1.0 to 0.125, and then changing the ratio of the flow rates of the nitrogen gas with respect to the inert gas to the larger side to form a rough TiN film, then exposing this rough TiN film to the atmosphere or a low vacuum atmosphere having a divided pressure of oxygen of 0.1 Pa or more so as to change the rough TiN film to a TiON film.).
Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date to have modified the process to include the steps disclosed in Sumi in order to achieve an improved barrier property (See Sumi, col. 8, lns. 6-9).
Claims 13, 14, and 16 are rejected under 35 U.S.C. 103 as being unpatentable over Cheng et al. (US 20200135475 A1) in view of Hempel et al. (US 20120315749 A1) and Hwang et al. (US 20120256276 A1), hereinafter “Huang.”
Re: Claim 13, the combination of Cheng and Hempel discloses the method of claim 12.
However, while the combination of Cheng and Hempel discloses multiple TiN caps as disclosed above, the combination does not clearly disclose before the depositing of the second TiN capping layer, further comprising:
depositing a middle TiN capping layer over the first TiN capping layer; and
performing an oxygen treatment to the middle TiN capping layer, wherein the second TiN capping layer is deposited over the middle TiN capping layer.
In a similar field of endeavor, Huang discloses before the depositing of the second TiN capping layer, further comprising:
depositing a middle TiN capping layer over the first TiN capping layer (Fig. 1 shows multiple layers comprising TiN, TaN, TiN; ¶0017: a multi-layered stack structure 112 is formed on the high-k layer 104 (step 204, step 206, step 208). The multi-layered stack structure 112 includes two or more than two layers of metal/metal nitride. In one embodiment, the multi-layered stack structure 112 includes a first layer 106 including TiN, a second layer 108 including TaN and a third layer 110 including TiN.; ¶0025: The barrier layer 317 includes metal/metal nitride, in one preferred embodiment, the barrier layer 317 in TaN; Examiner Note: the language “including TiN/TaN” indicates these are examples and not exhaustive limitations. The reference states two or more than two layers of metal/metal nitride which allows flexibility including variations between TiN and TaN. ¶0025 indicates TaN is preferred for the specific embodiment but is not mandatory. Furthermore, TiN and TaN are both common metal nitrides in HKMG barriers/work-function layers.); and
performing an oxygen treatment to the middle TiN capping layer, wherein the second TiN capping layer is deposited over the middle TiN capping layer (Fig. 1 shows wherein an O2 ambience treatment may be performed on multiple layers of the TiN/TaN capping layers).
Therefore, it would have been obvious to a person of ordinary skill in the art before the effective filing date to have oxygenated regions, as disclosed by Huang, in order to improve the work function of the metal gate to achieve better performance (See Huang, ¶0038).
Re: claim 14, the combination of Cheng and Hempel discloses the method of claim 11.
Hempel further discloses wherein the TiN cap has an oxygenated region between a top and a bottom region (¶0045: wherein the oxygen gradient ranges between approximately 20-50 atomic weight percent),
Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date to have modified a TiN deposition process by exposing said material to an environment having oxygen in order to achieve desired device operating characteristics and threshold voltage (Vt) (See Hempel, ¶0038).
However, the combination does not disclose the oxygenated region having a higher oxygen concentration than the top and the bottom region.
In a similar field of endeavor, Huang discloses the oxygenated region having a higher oxygen concentration than the top and the bottom region (¶0019: By using the abovementioned O.sub.2 ambience treatment, at least one layer of the multi-layered stack structure 112 may include oxygen and the concentration of oxygen in the side closer to the metal layer 114 is greater than that in the side opposite from the metal layer 114.).
Therefore, it would have been obvious to a person of ordinary skill in the art before the effective filing date to have oxygenated regions, as disclosed by Huang, in order to improve the work function of the metal gate to achieve better performance (See Huang, ¶0038).
Re: Claim 16, the combination of Cheng and Hempel discloses the method of claim 11.
However, the combination does not specifically disclose wherein before the performing of the oxygen treatment, performing a cleaning process to a top surface of the first TiN capping layer.
In a similar field of endeavor, Huang discloses wherein before the performing of the oxygen treatment, performing a cleaning process to a top surface of the first TiN capping layer (¶0024: In another embodiment, the O.sub.2 ambience treatment can also be performed when forming the first etch stop layer 407 and the second etch stop layer 507. The O.sub.2 ambience treatment may include an annealing process, a plasma treatment process or a chemical treatment process. In one preferred embodiment… Chemical treatment includes using a chemical solvent containing NH.sub.4OH, H.sub.2O.sub.2 and H.sub.2O, such as SC.sub.1 solvent.).
Therefore, it would have been obvious to a person of ordinary skill in the art before the effective filing date to have oxygenated regions, as disclosed by Huang, in order to improve the work function of the metal gate to achieve better performance (See Huang, ¶0038).
Claims 17-19 are rejected under 35 U.S.C. 103 as being unpatentable over Cheng et al. (US 20200135475 A1) in view of Huang et al. (US 20120256276 A1).
Re: Independent Claim 17, Cheng discloses a method of forming a semiconductor device (See Fig. 1A), comprising:
forming a high-k gate dielectric layer over a channel region of a substrate (Fig. 1A, step 108 – form gate dielectric on interfacial layer; Fig. 6: dielectric layer 504; ¶0029: a gate dielectric layer 504 is formed on the interfacial layer 502 within the gate recess 402; ¶0030: Suitable materials for the gate dielectric layer 504 are… high-k dielectric materials such as HfO.sub.2);
depositing a work function metal layer over the high-k gate dielectric layer (Fig. 1B, step 124; ¶0053: Referring to block 124 of FIG. 1B and referring to FIGS. 12-14, one or more work function layers are formed… work function materials include TiN, TaN… TiAlN);
depositing a bottom titanium nitride (TiN) capping layer over the work function metal layer ¶0034: The first capping layer 602 may include any suitable protective material including metals (e.g., W, Al, Ta, Ti, Ni, Cu, Co, etc.), metal nitrides, and/or metal silicon nitrides. In various such embodiments, the first capping layer 602 includes TiSiN and/or TiN.;
…
…
…
depositing a top TiN capping layer over the one or more middle TiN capping layers to form a TiN cap (¶0037: The second capping layer 604 may include any suitable protective material including metals, semiconductors, and nitrides thereof. The second capping layer 604 may be the same or different in composition from the first capping layer 602, i.e., TiN);
depositing a silicon cap layer over the TiN cap (¶0037: In some embodiments, the second capping layer 604 includes amorphous silicon.; ¶0038: The deposition process may be configured to produce a second capping layer 604, which may be TiN.; ¶0068: a second capping layer is formed on the first capping layer… In some such embodiments, the first capping layer includes a metal nitride);
depositing a conductive glue layer over the silicon cap layer (¶0057: a glue layer 1206 is formed on the fourth capping layer 1204… The glue layer 1206 may contain any suitable material selected to promote adhesion between layers and may include metals, i.e., conductive, metal nitrides, and/or metal silicon nitrides, and in an example, the glue layer 1206 includes tungsten.); and
depositing a gate fill metal layer over the conductive glue layer to form a gate structure (Fig. 14: electrode fill 1208, i.e., gate fill; ¶0058: Referring to block 130 of FIG. 1B and to referring still to FIG. 14, an electrode fill 1208 is formed within the gate recesses 402 on the glue layer 1206.).
While Cheng discloses multiple layers including TiN cap layers and performing an anneal wherein the first capping layer includes nitrogen as a source for passivation where nitrogen is diffused into the high-k dielectric material to compensate for oxygen vacancies in the high-k dielectric material (See Cheng, ¶0034), Cheng does not specifically disclose performing an oxygen treatment to the bottom TiN capping layer; depositing one or more middle TiN capping layers over the bottom TiN layer; performing an oxygen treatment to the one or more middle TiN capping layers;
In a similar field of endeavor, Huang discloses performing an oxygen treatment to the bottom TiN capping layer (Fig. 1, steps 204 and 214);
depositing one or more middle TiN capping layers over the bottom TiN layer (Fig. 1, steps 206, 216, 208, and 218; ¶0017: a multi-layered stack structure 112 is formed on the high-k layer 104 (step 204, step 206, step 208). The multi-layered stack structure 112 includes two or more than two layers of metal/metal nitride. In one embodiment, the multi-layered stack structure 112 includes a first layer 106 including TiN, a second layer 108 including TaN and a third layer 110 including TiN.);
performing an oxygen treatment to the one or more middle TiN capping layers (Fig. 1, steps 206 and 216);
Therefore, it would have been obvious to a person of ordinary skill in the art before the effective filing date to have oxygenated regions, as disclosed by Huang, in order to improve the work function of the metal gate to achieve better performance (See Huang, ¶0038).
Re: Claim 18, the combination of Cheng and Huang discloses the method of claim 17.
Huang further discloses wherein an oxygen treatment is performed for every middle TiN capping layer deposited (Fig. 1 shows multiple layers comprising TiN, TaN, TiN; ¶0017: a multi-layered stack structure 112 is formed on the high-k layer 104 (step 204, step 206, step 208). The multi-layered stack structure 112 includes two or more than two layers of metal/metal nitride. In one embodiment, the multi-layered stack structure 112 includes a first layer 106 including TiN, a second layer 108 including TaN and a third layer 110 including TiN.; ¶0025: The barrier layer 317 includes metal/metal nitride, in one preferred embodiment, the barrier layer 317 in TaN; Examiner Note: the language “including TiN/TaN” indicates these are examples and not exhaustive limitations. The reference states two or more than two layers of metal/metal nitride which allows flexibility including variations between TiN and TaN. ¶0025 indicates TaN is preferred for the specific embodiment but is not mandatory. Furthermore, TiN and TaN are both common metal nitrides in HKMG barriers/work-function layers.).
Therefore, it would have been obvious to a person of ordinary skill in the art before the effective filing date to have oxygenated regions, as disclosed by Huang, in order to improve the work function of the metal gate to achieve better performance (See Huang, ¶0038).
Re: Claim 19, the combination of Cheng and Huang discloses the method of claim 17.
Huang further discloses wherein the TiN cap includes multiple oxygenated regions interposed between non-oxygenated regions (Fig. 1 shows multiple oxygenated regions 204, 206, and 208 between non-oxygenated regions 202 and 210.),
wherein the oxygenated regions have a higher concentration of oxygen than the non-oxygenated regions (¶0019: By using the abovementioned O.sub.2 ambience treatment, at least one layer of the multi-layered stack structure 112 may include oxygen and the concentration of oxygen in the side closer to the metal layer 114 is greater than that in the side opposite from the metal layer 114.).
Therefore, it would have been obvious to a person of ordinary skill in the art before the effective filing date to have oxygenated regions, as disclosed by Huang, in order to improve the work function of the metal gate to achieve better performance (See Huang, ¶0038).
Claim 20 is rejected under 35 U.S.C. 103 as being unpatentable over Cheng et al. (US 20200135475 A1) in view of Huang et al. (US 20120256276 A1) and Hempel et al. (US 20120315749 A1).
Re: Claim 20, the combination of Cheng and Huang discloses the method of claim 17.
Both Cheng and Huang disclose annealing processes while Huang further discloses performing oxygen treatments as disclosed previously. However, for the purpose of compact prosecution, Hempel is being introduced to teach the exact wording in claim 19.
In a similar field of endeavor, Hempel discloses further comprising:
performing an annealing process to the gate structure such that oxygen atoms in the TIN cap diffuses into the high-k gate dielectric layer (¶0039: first sub-layer 215a by forming two separate cap layer portions, as well as to perform additional intermediate treatment and processing steps so as to adjust the oxygen and nitrogen content distribution within the first sub-layer 215a.; ¶0040: oxygen atoms diffuse into the first metal gate cap layer 215a-1 and along the grain boundaries toward the interface 210i, thereby increasing the overall oxygen content of the first metal gate cap layer 215a-1.; ¶0043: During the thermal treatment 235, at least some of the oxygen atoms present in the first sub-layer 215a--including at least some of the oxygen atoms previously diffused into the first metal gate cap layer 215a-1 during the oxygen diffusion process 234--may be driven toward the interface 210i and the layer of high-k dielectric material 214, thereby raising the oxygen content in the lower portion of the first sub-layer 215a (i.e., in the first metal gate cap layer 215a-1) and around the interface 210i.).
Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date to have modified a TiN deposition process by exposing said material to an environment having oxygen in order to achieve desired device operating characteristics and threshold voltage (Vt) (See Hempel, ¶0038).
Conclusion
The prior art made of record and not relied upon is considered pertinent to applicant's disclosure:
Gandikota et al. (US 20210111020 A1 - See Fig. 2
Lee et al. (US 20210249315 A1) – See Figs. 16 & 17
Any inquiry concerning this communication or earlier communications from the examiner should be directed to WILLIAM ADROVEL whose telephone number is (571)272-3048. The examiner can normally be reached 7:30 AM - 5:00 PM.
Examiner interviews are available via telephone, in-person, and video conferencing using a USPTO supplied web-based collaboration tool. To schedule an interview, applicant is encouraged to use the USPTO Automated Interview Request (AIR) at http://www.uspto.gov/interviewpractice.
If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, LEONARD CHANG can be reached at (571) 270-3691. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300.
Information regarding the status of published or unpublished applications may be obtained from Patent Center. Unpublished application information in Patent Center is available to registered users. To file and manage patent submissions in Patent Center, visit: https://patentcenter.uspto.gov. Visit https://www.uspto.gov/patents/apply/patent-center for more information about Patent Center and https://www.uspto.gov/patents/docx for information about filing in DOCX format. For additional questions, contact the Electronic Business Center (EBC) at 866-217-9197 (toll-free). If you would like assistance from a USPTO Customer Service Representative, call 800-786-9199 (IN USA OR CANADA) or 571-272-1000.
/WILLIAM ADROVEL/Examiner, Art Unit 2898
/Leonard Chang/Supervisory Patent Examiner, Art Unit 2898
Prosecution Insights