DETAILED ACTION
Response to Arguments
Applicant’s arguments, see pages 8-9, filed 05/06/2026, with respect to the rejection(s) of claim(s) 1-8, 11, 12 and 15 under 35 U.S.C. § 103 have been fully considered and are persuasive. Therefore, the rejection has been withdrawn. However, upon further consideration, a new ground(s) of rejection is made as detailed below.
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 and 15 are rejected under 35 U.S.C. 103 as being unpatentable over ANDO et al. (US 20200365584 A1), hereinafter “Ando,” in view of HEMPEL et al. (US 201203157749 A1, cited in previous office action), hereinafter “Hempel,” and further in view of KWON et al. (US 20190386136 A1), hereinafter “Kwon.”
Re: Independent Claim 1, Ando discloses a method of forming a semiconductor device (¶0027: provides a structure and a method of forming), comprising:
forming a high-k gate dielectric layer over a channel region of a substrate (Fig. 3: high-k 15B over channel 13; ¶0043: deposition of a high-k dielectric material for dielectric 15B);
depositing a work function metal layer over the high-k gate dielectric layer (Fig. 4: WFM 16 over HK 15B; ¶0045: depositing WFM on dielectric 15B);
…
depositing a conductive glue layer over the … cap layer (Fig. 7: liner 18, i.e., conductive glue layer, such as TiN; ¶0048: ORL 17 is deposited over WFM 16, i.e., cap layer; ¶0049: ORL 17 is composed of SiO… ORL 17 is not limited to SiO or SiON but, may be composed of other suitable material capable of providing an oxygen reservoir, such as TiO.sub.2 or other suitable oxide material; ¶0052: depositing liner 18 composed of TiN on ORL 17); and
depositing a gate fill metal layer over the conductive glue layer to form a gate structure (¶0053: LRM 19 is deposited over exposed surfaces of semiconductor structure 800 (e.g., deposited over liner 18); ¶0054: LRM 19 is composed of tungsten).
While Ando discloses providing an oxygenated layer (ORL 17) which supplies oxygen to a high-k layer, Ando does not specifically disclose
forming a titanium nitride (TiN) cap over the work function metal layer, wherein the TiN cap includes one or more oxygenated regions;
depositing a silicon cap layer over the TiN cap;
… silicon cap
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 oxygenated regions (Figs. 2b-2d show TiN cap 215a; ¶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).
However, the combination of Ando in view of Hempel does not specifically disclose
depositing a silicon cap layer over the TiN cap;
… silicon cap
In a similar field of endeavor, Kwon discloses depositing a silicon cap layer over the TiN cap (¶¶0018-0019: silicon layer 26’ formed over TiN 25’);
… silicon cap (¶0019: silicon layer 26’)
Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date to have incorporated a silicon cap, as disclosed by Kwon, over a TiN layer in order to block excess oxygen from affective a gate insulation layer during an annealing process (See Kwon, ¶0019).
Furthermore, Ando discloses the basic gate-stack architecture in claim 1. Ando’s state purpose for the upper oxygen reservoir is to supply oxygen that stabilizes the effective work function of the high-k metal and prevents unwanted threshold-voltage shift during subsequent thermal processing. Hempel discloses the missing oxygenated-TiN teaching which Ando lacks. Hempel also discloses a thermal treatment that drives oxygen from the oxygenated TiN toward the high-k dielectric in order to increase oxygen content near the high-k interface in a controlled manner for the purpose of achieving desired device operating characteristics and threshold-voltage. Kwon further teaches supplying a silicon cap over a TiN-containing structure specifically so that the silicon interferes with or blocks excess oxygen which prevents uncontrolled oxygen from reaching the underlying layers and allows the oxygen already present in the TiN to be the main supply of oxygen.
Re: Claim 2, the combination of Ando in view of Hempel and Kwon 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… ; ¶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 Ando in view of Hempel and Kwon discloses the method of claim 2.
Kwon 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 (¶0019: preliminary sacrificial layer 26′ may interfere with or block supply of excess oxygen to the preliminary gate insulator layer 24′ during a subsequent annealing process (See e.g., FIG. 8).).
Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date to have incorporated a silicon cap, as disclosed by Kwon, over a TiN layer in order to block excess oxygen from affecting a gate insulation layer during an annealing process (See Kwon, ¶0019).
Re: Claim 4, the combination of Ando in view of Hempel and Kwon discloses the method of claim 1.
Hempel further discloses wherein the forming of the TiN cap includes (¶0039: FIG. 2a is adapted to form the first sub-layer 215a by forming two separate cap layer portions):
depositing a first TiN capping layer over the work function metal layer (Note: Ando discloses depositing a layer having an oxygen reservoir above a work function metal layer as taught above; Hempel Figs. 2b-2d show layer 215a; ¶0038: 215a may comprise TiN; ¶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.);
performing an oxygen treatment to the first TiN capping layer (Fig. 2c: oxygen diffusion process 234; ¶0040: oxygen diffusion process 234, oxygen atoms diffuse into the first metal gate cap layer 215a-1); and
depositing a second TiN capping layer over the first TiN capping layer (Fig. 2d: conformal deposition process 233c; ¶0042: 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… second metal gate cap layer 215a-2 may comprise substantially the same material as the first metal gate cap layer 215a-1, such as, for example, TiN and the like).
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 Ando in view of Hempel and Kwon discloses the method of claim 4.
Hempel further discloses wherein the first TiN capping layer is deposited in a vacuum sealed physical vapor deposition (PVD) chamber (¶0039: FIG. 2a is adapted to form the first sub-layer 215a by forming two separate cap layer portions… performing a suitably designed conformal deposition process 233a, such as a physical vapor deposition (PVD) process, i.e., vacuum sealed), wherein the oxygen treatment includes: removing a workpiece having the first TiN capping layer from the PVD chamber (¶0040: 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… 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: 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… 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.).
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 Ando in view of Hempel and Kwon discloses the method of claim 5.
Hempel further discloses wherein the environment is air at room temperature (¶0040: 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, …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 Ando in view of Hempel and Kwon 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: 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… 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 Ando in view of Hempel and Kwon 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, Ando discloses a method of forming a semiconductor device (¶0027: provides a structure and a method of forming), comprising:
forming a high-k gate dielectric layer over a channel region of a substrate (Fig. 3: high-k 15B over channel 13; ¶0043: deposition of a high-k dielectric material for dielectric 15B);
depositing a work function metal layer over the high-k gate dielectric layer (Fig. 4: WFM 16 over HK 15B; ¶0045: depositing WFM on dielectric 15B);
…
depositing a conductive glue layer over the … cap layer (Fig. 7: liner 18, i.e., conductive glue layer, such as TiN; ¶0048: ORL 17 is deposited over WFM 16, i.e., cap layer; ¶0049: ORL 17 is composed of SiO… ORL 17 is not limited to SiO or SiON but, may be composed of other suitable material capable of providing an oxygen reservoir, such as TiO.sub.2 or other suitable oxide material; ¶0052: depositing liner 18 composed of TiN on ORL 17); and
depositing a gate fill metal layer over the conductive glue layer to form a gate structure (¶0053: LRM 19 is deposited over exposed surfaces of semiconductor structure 800 (e.g., deposited over liner 18); ¶0054: LRM 19 is composed of tungsten).
While Ando discloses providing an oxygenated layer (ORL 17) which supplies oxygen to a high-k layer, Ando does not specifically disclose depositing a first titanium nitride (TiN) capping layer over the work function metal layer; performing an oxygen treatment to the first TiN capping layer; depositing a second TiN capping layer over the first TiN capping layer to form a TiN cap; depositing a silicon cap layer over the TiN cap; or … silicon cap
In a similar field of endeavor, Hempel discloses
depositing a first titanium nitride (TiN) capping layer over the work function metal layer (Note: Ando discloses depositing a layer having an oxygen reservoir above a work function metal layer as taught above; Hempel - Figs. 2b-2d show TiN cap 215a; ¶0039: 215a cap layer);
performing an oxygen treatment to the first TiN capping layer (Fig. 2c: oxygen diffusion process 234; ¶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);
depositing a second TiN capping layer over the first TiN capping layer to form a TiN cap (Fig. 2d: conformal deposition process 233c; ¶0042: 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… second metal gate cap layer 215a-2 may comprise substantially the same material as the first metal gate cap layer 215a-1, such as, for example, TiN and the like);
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 of Ando in view of Hempel does not specifically disclose
depositing a silicon cap layer over the TiN cap;
… silicon cap
In a similar field of endeavor, Kwon discloses depositing a silicon cap layer over the TiN cap (¶¶0018-0019: silicon layer 26’ formed over TiN 25’);
… silicon cap (¶0019: silicon layer 26’)
Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date to have incorporated a silicon cap, as disclosed by Kwon, over a TiN layer in order to block excess oxygen from affective a gate insulation layer during an annealing process (See Kwon, ¶0019).
Re: Claim 15, the combination of Ando in view of Hempel and Kwon 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 and 10 are rejected under 35 U.S.C. 103 as being unpatentable over ANDO et al. (US 20200365584 A1), in view of HEMPEL et al. (US 201203157749 A1), KWON et al. (US 20190386136 A1), and SUMI et al. (US 5763948, cited in previous office action), hereinafter “Sumi.”
Re: Claim 9, the combination of Ando in view of Hempel and Kwon discloses the method of claim 4.
However, the combination of Ando in view of Hempel and Kwon does 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 Ando in view of Hempel and Kwon 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 14 and 16 are rejected under 35 U.S.C. 103 as being unpatentable over ANDO et al. (US 20200365584 A1), in view of HEMPEL et al. (US 201203157749 A1), KWON et al. (US 20190386136 A1), and HUANG et al. (US 20120256276 A1, cited in previous office action), hereinafter “Huang.”
Re: Claim 14, the combination of Ando in view of Hempel and Kwon 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 Ando in view of Hempel and Kwon discloses the method of claim 11.
However, the combination of Ando in view of Hempel and Kwon 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 17-20 are rejected under 35 U.S.C. 103 as being unpatentable over ANDO et al. (US 20200365584 A1), in view of HEMPEL et al. (US 201203157749 A1), HUANG et al. (US 20120256276 A1) and KWON et al. (US 20190386136 A1).
Re: Independent Claim 17, Ando discloses a method of forming a semiconductor device (¶0027: provides a structure and a method of forming), comprising:
forming a high-k gate dielectric layer over a channel region of a substrate (Fig. 3: high-k 15B over channel 13; ¶0043: deposition of a high-k dielectric material for dielectric 15B);
depositing a work function metal layer over the high-k gate dielectric layer (Fig. 4: WFM 16 over HK 15B; ¶0045: depositing WFM on dielectric 15B);
…
depositing a conductive glue layer over the … cap layer (Fig. 7: liner 18, i.e., conductive glue layer, such as TiN; ¶0048: ORL 17 is deposited over WFM 16, i.e., cap layer; ¶0049: ORL 17 is composed of SiO… ORL 17 is not limited to SiO or SiON but, may be composed of other suitable material capable of providing an oxygen reservoir, such as TiO.sub.2 or other suitable oxide material; ¶0052: depositing liner 18 composed of TiN on ORL 17); and
depositing a gate fill metal layer over the conductive glue layer to form a gate structure (¶0053: LRM 19 is deposited over exposed surfaces of semiconductor structure 800 (e.g., deposited over liner 18); ¶0054: LRM 19 is composed of tungsten).
While Ando discloses providing an oxygenated layer (ORL 17) which supplies oxygen to a high-k layer, Ando does not specifically disclose depositing a bottom titanium nitride (TiN) capping layer over the work function metal layer; 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;
depositing a top TiN capping layer over the one or more middle TiN capping layers to form a TiN cap; depositing a silicon cap layer over the TiN cap; or … silicon cap
In a similar field of endeavor, Hempel discloses depositing a bottom titanium nitride (TiN) capping layer over the work function metal layer (Note: Ando discloses depositing a layer having an oxygen reservoir above a work function metal layer as taught above; Hempel - Figs. 2b-2d show TiN cap 215a; ¶0039: 215a cap layer, i.e., bottom TiN capping layer);
performing an oxygen treatment to the bottom TiN capping layer (Fig. 2c: oxygen diffusion process 234; ¶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);
…
depositing a top TiN capping layer over the one or more middle TiN capping layers to form a TiN cap (Fig. 2d: conformal deposition process 233c; ¶0042: 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… second metal gate cap layer 215a-2 may comprise substantially the same material as the first metal gate cap layer 215a-1, such as, for example, TiN and the like);
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 of Ando in view of Hempel does not specifically disclose 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; depositing a silicon cap layer over the TiN cap; … silicon cap
In a similar field of endeavor, Huang discloses
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).
However, the combination of Ando in view of Hempel and Huang does not seem to specifically disclose depositing a silicon cap layer over the TiN cap; or … silicon cap.
In a similar field of endeavor, Kwon discloses depositing a silicon cap layer over the TiN cap (¶¶0018-0019: silicon layer 26’ formed over TiN 25’);
… silicon cap (¶0019: silicon layer 26’)
Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date to have incorporated a silicon cap, as disclosed by Kwon, over a TiN layer in order to block excess oxygen from affective a gate insulation layer during an annealing process (See Kwon, ¶0019).
Re: Claim 18, the combination of Ando in view of Hempel, Huang and Kwon 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 Ando in view of Hempel, Huang and Kwon 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).
Re: Claim 20, the combination of Ando in view of Hempel, Huang and Kwon discloses the method of claim 17.
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 (¶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).
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).
Allowable Subject Matter
Claims 12 and 13 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. Regarding claim 12, Ando does not seem to disclose the steps of performing a sacrificial capping layer over the high-k gate dielectric layer and then performing a first annealing before further removing the sacrificial capping layer and then afterwards performing a second annealing.
Conclusion
The prior art made of record and not relied upon is considered pertinent to applicant's disclosure:
ANDO et al. (US 20180240865 A1) – See FIG. 1 where a germanium oxide/titanium nitride (GeOx/TiN) cap is deposited over the work function stack.
LIM (US 9,859,392 B2) – See Figs. 2 and 3
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/WILLIAM ADROVEL/ Examiner, Art Unit 2898
/Leonard Chang/ Supervisory Patent Examiner, Art Unit 2898
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