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 .
Claims 1-20 are pending
Claim Rejections - 35 USC § 112
The following is a quotation of 35 U.S.C. 112(b):
(b) CONCLUSION.—The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the inventor or a joint inventor regards as the invention.
The following is a quotation of 35 U.S.C. 112 (pre-AIA ), second paragraph:
The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the applicant regards as his invention.
Claims 7 and 15 are rejected under 35 U.S.C. 112(b) or 35 U.S.C. 112 (pre-AIA ), second paragraph, as being indefinite for failing to particularly point out and distinctly claim the subject matter which the inventor or a joint inventor (or for applications subject to pre-AIA 35 U.S.C. 112, the applicant), regards as the invention.
The term “stronger” in claims 7 and 15 is a relative term which renders the claim indefinite. The term “stronger” is not defined by the claim, the specification does not provide a standard for ascertaining the requisite degree, and one of ordinary skill in the art would not be reasonably apprised of the scope of the invention.
Claims 7 and 15 recite wherein the second chemistry is selective to etch the metal mask layer stronger than the passivation layer. The term stronger is a relative term of degree that does not provide an objective boundary for determining the claimed degree of etching. Although paragraph [0036] of the instant specification describes stronger parenthetically as more, faster, the specification does not appear to provide an objective standard for determining the scope of the term, such as whether stronger is determined by etch rate, amount of material removed, an etch selectivity ratio, or another measurable criterion. Accordingly, one of ordinary skill in the art would not be reasonably apprised of the scope of stronger, thereby rendering claims 7 and 15 indefinite. See MPEP § 2173.05(b).
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 (i.e., changing from AIA to pre-AIA ) 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, 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.
The factual inquiries for establishing a background for determining obviousness under 35 U.S.C. 103 are summarized as follows:
1. Determining the scope and contents of the prior art.
2. Ascertaining the differences between the prior art and the claims at issue.
3. Resolving the level of ordinary skill in the pertinent art.
4. Considering objective evidence present in the application indicating obviousness or nonobviousness.
This application currently names joint inventors. In considering patentability of the claims the examiner presumes that the subject matter of the various claims was commonly owned as of the effective filing date of the claimed invention(s) absent any evidence to the contrary. Applicant is advised of the obligation under 37 CFR 1.56 to point out the inventor and effective filing dates of each claim that was not commonly owned as of the effective filing date of the later invention in order for the examiner to consider the applicability of 35 U.S.C. 102(b)(2)(C) for any potential 35 U.S.C. 102(a)(2) prior art against the later invention.
Claims 1-6, 8, and 11 are rejected under 35 U.S.C. 103 as being unpatentable over Yoon et al. (US 2016/0314981 A1) in view of Wu et al. (US 2006/0006545 A1) and further in view of Shaw et al. (US 2022/0068661 A1).
Regarding claim 1, Yoon teaches receiving a substrate having a metal mask layer thereon and a first mask layer over the metal mask layer, wherein the first mask layer is patterned having holes that open to the metal mask layer (metal layer 12 is formed over lower layer 11 and mask layer 13 is formed over metal layer 12 having opening 17 that exposes the surface of metal layer 12; paragraphs [0049]-[0052]).
Yoon teaches passivating a surface of the metal mask layer in the holes using a first chemistry to form a passivation layer on the surface of the metal mask layer, wherein the first chemistry contains hydrogen (first passivation layer 15a is formed over the inner surface of hole 18 by a plasma passivation process, wherein oxygen and hydrogen may be used together to form the first passivation layer and hydrogen adjusts the oxidation rate; paragraphs [0056], [0063]).
Yoon teaches performing an anisotropic etch with a second chemistry to remove first passivation portions of the passivation layer and first metal portions of the metal mask layer at bottoms of the holes to increase hole depths of the holes in the metal mask layer (the chlorine-based plasma etch removes first passivation layer 15a from floor surface 19a to expose and etch metal layer 12, while passivation on the inner sidewall remains, thereby increasing hole 18 from first depth D1 to second depth D2; the chlorine-based plasma etch is substrate-biased and directed downward through the metal layer to form a vertical pattern; paragraphs [0022], [0057]-[0058], [0101]-[0103]).
Yoon further teaches wherein the second chemistry contains boron and chlorine (boron or a boron-containing gas such as BCl3 may be added to a chlorine-based etch gas such as Cl2; paragraph [0064]).
Yoon does not expressly teach wherein the metal mask layer contains tungsten, silicon, and nitrogen.
Wu teaches wherein the metal mask layer contains tungsten, silicon, and nitrogen (a semiconductor hardmask layer may comprise tungsten silicon nitride (WSiN); paragraph [0022]).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify the method of Yoon to include a metal mask layer containing WSiN as taught by Wu because Wu teaches WSiN as a known material suitable for use as a semiconductor hardmask layer, and simple substitution of one known hardmask material for another to obtain predictable results is obvious, see MPEP 2141 III(B).
Modified Yoon does not expressly teach wherein the first chemistry contains sulfur and hydrogen. Modified Yoon teaches hydrogen in the first chemistry as discussed above, but does not expressly teach sulfur.
Shaw teaches wherein the first chemistry contains sulfur (SO2 is used as a passivation gas to form a passivation layer on exposed surfaces of a metal-containing layer, thereby protecting the sidewall profile during subsequent metal etching and reducing undercut and bowing; paragraphs [0070]-[0074]).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to further modify the method of modified Yoon to include SO2 in the hydrogen-containing first chemistry as taught by Shaw because Shaw teaches SO2 as a known metal-sidewall passivation gas for reducing undercut and bowing and maintaining the sidewall profile during subsequent metal etching, and use of a known technique to improve similar methods in the same way is obvious, see MPEP 2141 III(C).
Regarding claim 2, modified Yoon teaches the limitations of claim 1 as discussed above.
Modified Yoon further teaches wherein second passivation portions of the passivation layer remain on at least part of sidewalls of the holes after the anisotropic etch (first passivation layer 15a remains on the inner sidewall of hole 18 while the portion of the passivation layer at the floor is removed and the metal layer is further etched, thereby protecting the sidewall from undercut; paragraphs [0057]-[0058]).
Regarding claim 3, modified Yoon teaches the limitations of claim 1 as discussed above.
Modified Yoon further teaches wherein the first chemistry is formed by flowing a first gas mixture containing sulfur dioxide (SO2) and hydrogen (H2) (Yoon teaches forming the passivation layer using a mixed gas containing hydrogen, and Shaw teaches including SO2 as the passivation gas for forming a protective passivation layer on exposed metal surfaces; Yoon paragraph [0063]; Shaw paragraphs [0093]-[0095]).
Regarding claim 4, modified Yoon teaches the limitations of claim 3 as discussed above.
Modified Yoon further teaches wherein the second chemistry is formed by flowing a second gas mixture containing boron trichloride (BCl3) and chlorine (Cl2) (the chlorine-based etch gas may include Cl2 and BCl3, and BCl3 may be mixed with the Cl2-containing etch gas to adjust the etch rate; paragraphs [0019]-[0020], [0064]).
Regarding claim 5, modified Yoon teaches the limitations of claim 1 as discussed above.
Modified Yoon further teaches wherein the second chemistry is formed by flowing a second gas mixture containing boron trichloride (BCl3) and chlorine (Cl2) (the chlorine-based etch gas may contain Cl2 and BCl3, and BCl3 may be mixed with the Cl2-containing etch gas to increase the etch rate; paragraphs [0019]-[0020], [0064]).
Regarding claim 6, modified Yoon teaches the limitations of claim 1 as discussed above.
Modified Yoon does not expressly teach wherein the anisotropic etch includes bombarding the passivation layer at the bottoms of the holes with ions traveling perpendicular to the substrate.
Shaw teaches directing an anisotropic ion flux toward horizontal surfaces of a substrate, including the bottom surface of a feature (substrate bias directs an ion flux toward the horizontal surfaces, wherein ions bombard and directionally etch material at the bottom surface relative to the sidewalls; paragraphs [0064]-[0065]).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to further modify the method of modified Yoon to direct the anisotropic ion flux toward the passivation layer at the bottoms of the holes as taught by Shaw because Shaw teaches that substrate-biased directional ion bombardment preferentially removes material from horizontal bottom surfaces relative to vertical sidewalls, thereby providing controlled anisotropic etching, and use of a known technique to improve similar methods in the same way is obvious, see MPEP 2141 III(C).
Regarding claim 8, modified Yoon teaches the limitations of claim 1 as discussed above.
Modified Yoon further teaches wherein the performing of the anisotropic etch includes reactive ion etching (the chlorine-based plasma etch is performed using RF plasma with bias power applied to the substrate-supporting electrostatic chuck, wherein the bias power is greater than the plasma-source power during the etch process and directs the etchant downward through the metal layer to form a vertical pattern; paragraphs [0022], [0096]-[0097], [0101]-[0103]).
Regarding claim 11, modified Yoon teaches the limitations of claim 1 as discussed above.
Modified Yoon further teaches wherein a carrier gas for the second chemistry comprises Ar or He (Yoon teaches that the chlorine-based etch gas may further include an inert gas such as argon (Ar) or helium (He) for generating the plasma; paragraph [0053]; Yoon further teaches adding Ar or He to the chlorine-based etch gas; paragraph [0064]).
Modified Yoon does not expressly teach wherein a carrier gas for the first chemistry comprises one of or any combination of Ar, He, Kr, and Xe.
Shaw teaches an SO2-containing plasma gas mixture further containing Ar as an inert gas (an exemplary gas mixture includes O2, Cl2, SO2, and Ar; paragraph [0070]).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to further modify the method of modified Yoon to include Ar as a carrier gas for the first chemistry as taught by Shaw because Shaw teaches using Ar as an inert gas in an SO2-containing plasma gas mixture, and combining prior art elements according to known methods to yield predictable results is obvious, see MPEP 2141 III(A).
Claim 7 is rejected under 35 U.S.C. 103 as being unpatentable over Yoon et al. in view of Wu et al. and Shaw et al., as applied to claim 1 above, and further in view of Subramanian et al. (US 2014/0120727 A1).
Regarding claim 7, modified Yoon teaches the limitations of claim 1 as discussed above.
Modified Yoon does not expressly teach wherein the second chemistry is selective to etch the metal mask layer stronger than the passivation layer.
Subramanian teaches wherein the second chemistry is selective to etch the metal mask layer stronger than the passivation layer (the passivation layer is etched more slowly than the tungsten-containing layer; claim 11; see also paragraph [0015], teaching that sidewalls having the passivation layer are etched more slowly than the open front of the feature).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to further modify the method of modified Yoon to include a second chemistry selective to etch the metal mask layer stronger than the passivation layer as taught by Subramanian because Subramanian teaches that the slower etching of the passivated portions protects the sidewalls while allowing the exposed tungsten-containing layer to be etched to deepen the feature, and use of known technique to improve similar methods in the same way is obvious, see MPEP 2141 III(C).
Claim 9 is rejected under 35 U.S.C. 103 as being unpatentable over Yoon et al. in view of Wu et al. and Shaw et al., as applied to claim 1 above, and further in view of Louro and Cavaleiro, Hardness versus structure in W-Si-N sputtered coatings, Surface and Coatings Technology, Vols. 116–119, pp. 74–80 (1999).
Regarding claim 9, modified Yoon teaches the limitations of claim 1 as discussed above.
Modified Yoon does not expressly teach wherein the metal mask layer contains 59–63% tungsten, 21–25% silicon, and 14–18% nitrogen.
Louro teaches sputtered W-Si-N films in which the relative amounts of tungsten, silicon, and nitrogen are controlled by the sputtering conditions. In particular, for films deposited using 12 silicon pieces, Louro teaches a W69.2Si22.6N8.2 composition at an N2/Ar partial-pressure ratio of 1/8 and a W53.8Si24.2N22.0 composition at an N2/Ar partial-pressure ratio of 1/6.5, such that the silicon content of both compositions is within the claimed 21–25 at.% range while the tungsten and nitrogen contents lie on opposite sides of the claimed 59–63 at.% tungsten and 14–18 at.% nitrogen ranges (Table 2, p. 77).
Louro further teaches that, independent of the silicon content in the target, increasing the N2/Ar partial-pressure ratio increases the nitrogen content incorporated into the W-Si-N film, and that the relative silicon and nitrogen contents affect the resulting film structure and hardness (pp. 76–80). In particular, Louro evaluates hardness as a function of nitrogen content and teaches that changes in silicon content and the resulting film structure are associated with changes in hardness, including increased hardness with increasing silicon content for the crystalline films and different hardness behavior between crystalline and amorphous W-Si-N films (Fig. 6, p. 79; Table 3 and Conclusions, p. 80).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to further modify the WSiN metal mask layer of modified Yoon to have tungsten, silicon, and nitrogen contents within the claimed ranges by optimizing the relative W/Si/N composition through adjustment of the N2/Ar partial-pressure ratio as taught by Louro because Louro teaches that the nitrogen partial-pressure ratio controls the nitrogen content of the W-Si-N film and that the relative Si and N contents affect the resulting film structure and hardness. Thus, the relative W/Si/N composition was recognized as affecting a result of the film, and discovering optimum or workable ranges of a result-effective variable by routine experimentation is ordinarily obvious, see MPEP § 2144.05(II)(B).
Claim 10 is rejected under 35 U.S.C. 103 as being unpatentable over Yoon et al. in view of Wu et al. and Shaw et al., as applied to claim 1 above, and further in view of Ferreira et al. (Influence of Heat Treatment on the Structure of W-Si-N Sputtered Films, Key Engineering Materials, Vols. 230–232, pp. 640–643 (2002)).
Regarding claim 10, modified Yoon teaches the limitations of claim 1 as discussed above.
Modified Yoon does not expressly teach wherein the metal mask layer contains 61–65% tungsten, 9–13% silicon, and 23–27% nitrogen.
Ferreira teaches wherein a W-Si-N layer contains 61–65% tungsten, 9–13% silicon, and 23–27% nitrogen (a sputter-deposited W-Si-N film has a composition of W64Si9N27, corresponding to 64 at.% tungsten, 9 at.% silicon, and 27 at.% nitrogen; p. 640; see also pp. 642–643 and Fig. 4).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to further modify the method of modified Yoon such that the WSiN metal mask layer contains 64% tungsten, 9% silicon, and 27% nitrogen as taught by Ferreira because Ferreira teaches W64Si9N27 as a known sputter-deposited W-Si-N film composition and teaches that the structure of W-Si-N films depends on their chemical composition. Thus, using Ferreira’s known W-Si-N composition for the WSiN hard mask taught by Wu would have predictably provided a WSiN layer having a known and characterized composition, and combining prior art elements according to known methods to yield predictable results is obvious, see MPEP 2141 III(A).
Claims 12, 14, and 18 are rejected under 35 U.S.C. 103 as being unpatentable over Yoon et al. (US 2016/0314981 A1) in view of Wu et al. (US 2006/0006545 A1) and further in view of Shaw et al. (US 2022/0068661 A1).
Regarding claim 12, Yoon teaches depositing a metal mask layer over a substrate (metal layer 12 is formed on lower layer 11, wherein lower layer 11 may comprise silicon, silicon oxide, silicon nitride, or a combination thereof; paragraph [0049]).
Yoon teaches depositing a first mask layer over the metal mask layer and patterning and etching the first mask layer to form holes in the first mask layer, wherein the holes open to the metal mask layer (mask layer 13 is formed on metal layer 12 and includes opening 17 exposing metal layer 12; paragraphs [0050]-[0051]).
Yoon teaches performing a first anisotropic etch to remove first metal portions of the metal mask layer at first bottoms of the holes to form first hole depths of the holes in the metal mask layer (metal layer 12 is plasma etched through opening 17 using mask layer 13 as an etch mask to form hole 18 having first depth D1; the chlorine-based plasma etch is substrate-biased and directed downward through the metal layer to form a vertical pattern; paragraphs [0022], [0052]-[0054], [0101]-[0103]).
Yoon teaches passivating a surface of the metal mask layer in the holes using a first chemistry to form a passivation layer on the surface of the metal mask layer, wherein the first chemistry contains oxygen and hydrogen (first passivation layer 15a is formed over the inner surface of hole 18 using an oxygen plasma process, wherein hydrogen may be mixed with oxygen to adjust the oxidation rate; paragraphs [0056], [0063]).
Yoon teaches performing a second anisotropic etch with a second chemistry to remove first passivation portions of the passivation layer and second metal portions of the metal mask layer at second bottoms of the holes to form second hole depths of the holes in the metal mask layer, wherein second passivation portions of the passivation layer remain on at least part of sidewalls of the holes after the second anisotropic etch, and wherein the second hole depths are greater than the first hole depths (the chlorine-based plasma etch removes passivation layer 15a from floor surface 19a to expose and further etch metal layer 12 while passivation layer 15a remains on the inner sidewall, thereby increasing hole 18 from first depth D1 to second depth D2; the etch is directed downward through the metal layer to form a vertical pattern; paragraphs [0022], [0057]-[0058], [0101]-[0103]).
Yoon further teaches wherein the second chemistry contains boron and chlorine (boron or a boron-containing gas such as BCl3 may be added to a chlorine-based etch gas such as Cl2 to increase the etch rate; paragraph [0064]).
Yoon further teaches sequentially repeating the passivating with the first chemistry to form the passivation layer and the performing of the second anisotropic etch with the second chemistry until the holes open to the substrate through the metal mask layer (the oxidation and etch processes are repeatedly performed to progressively increase the depth of hole 18 until underlying lower layer 11 is exposed; paragraphs [0061]-[0062], [0068]-[0073]).
Yoon does not expressly teach wherein the metal mask layer contains tungsten, silicon, and nitrogen.
Wu teaches wherein the metal mask layer contains tungsten, silicon, and nitrogen (a semiconductor hardmask material may comprise tungsten silicon nitride (WSiN); paragraph [0022]).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify the method of Yoon to include a metal mask layer containing WSiN as taught by Wu because Wu teaches WSiN as a known material suitable for use as a semiconductor hardmask layer, and simple substitution of one known hardmask material for another to obtain predictable results is obvious, see MPEP 2141 III(B).
Modified Yoon does not expressly teach wherein the first chemistry contains sulfur, oxygen, and hydrogen. Modified Yoon teaches oxygen and hydrogen in the first chemistry as discussed above, but does not expressly teach sulfur.
Shaw teaches wherein the first chemistry contains sulfur (SO2 is used as a passivation gas for exposed surfaces of a metal-containing layer to form a passivation layer that protects the sidewall profile during subsequent metal etching and reduces undercut and bowing; paragraphs [0070]-[0074]).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to further modify the method of modified Yoon to include SO2 in the oxygen- and hydrogen-containing first chemistry as taught by Shaw because Shaw teaches SO2 as a known metal-sidewall passivation gas for reducing undercut and bowing and maintaining the sidewall profile during subsequent metal etching, and use of a known technique to improve similar methods in the same way is obvious, see MPEP 2141 III(C).
Regarding claim 14, modified Yoon teaches the limitations of claim 12 as discussed above.
Modified Yoon further teaches wherein the second anisotropic etch includes reactive ion etching by bombarding the passivation layer and the metal mask layer with ions traveling perpendicular to a top surface of the metal mask layer (the chlorine-based plasma etch is performed using RF plasma with bias power applied to the substrate-supporting electrostatic chuck, wherein the bias power is greater than the plasma-source power during the etch process and directs the plasma species downward through the metal layer to produce vertical etching; paragraphs [0022], [0101]-[0103]).
Regarding claim 18, modified Yoon teaches the limitations of claim 12 as discussed above.
Modified Yoon further teaches wherein the first chemistry is formed by flowing a first gas mixture containing sulfur dioxide (SO2) and hydrogen (H2) (Yoon teaches forming the passivation layer using a mixed gas containing hydrogen, and Shaw teaches including SO2 as a passivation gas, as discussed with respect to claim 12; Yoon paragraph [0063]; Shaw paragraphs [0070]-[0073]).
Modified Yoon further teaches wherein the second chemistry is formed by flowing a second gas mixture containing boron trichloride (BCl3) and chlorine (Cl2), and wherein a carrier gas for the second chemistry contains Ar (BCl3 may be added to a chlorine-based etch gas including Cl2, and Ar may further be added to the chlorine-based etch gas; paragraph [0064]).
Modified Yoon does not expressly teach wherein a carrier gas for the first chemistry contains Ar.
Shaw teaches an SO2-containing plasma gas mixture further containing Ar as an inert gas (an exemplary gas mixture includes O2, Cl2, SO2, and Ar; paragraph [0070]).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to further modify the method of modified Yoon to include Ar as a carrier gas for the first chemistry as taught by Shaw because Shaw teaches using Ar as an inert gas in an SO2-containing plasma gas mixture, and combining prior art elements according to known methods to yield predictable results is obvious, see MPEP 2141 III(A).
Claim 13 is rejected under 35 U.S.C. 103 as being unpatentable over Yoon et al. in view of Wu et al. and Shaw et al., as applied to claim 12 above, and further in view of Huang (US 6,150,073).
Regarding claim 13, the modified method of Yoon teaches the limitations of claim 12 as discussed above.
Modified Yoon does not expressly teach wherein the depositing of the metal mask layer includes physical vapor deposition.
Huang teaches wherein the depositing of the metal mask layer includes physical vapor deposition (hard mask layer 214, which may comprise tungsten nitride, is formed by chemical vapor deposition or physical vapor deposition (PVD); col. 3, ll. 13–18).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to further modify the method of modified Yoon to form the metal mask layer using physical vapor deposition as taught by Huang because Huang teaches physical vapor deposition as an identified technique for forming a metal hard mask layer, and choosing from a finite number of identified, predictable solutions with a reasonable expectation of success is obvious, see MPEP 2141 III(E).
Claim 15 is rejected under 35 U.S.C. 103 as being unpatentable over Yoon et al. in view of Wu et al. and Shaw et al., as applied to claim 12 above, and further in view of Subramanian et al. (US 2014/0120727 A1).
Regarding claim 15, the modified method of Yoon teaches the limitations of claim 12 as discussed above.
Modified Yoon does not expressly teach wherein the second chemistry is selective to etch the metal mask layer stronger than the passivation layer.
Subramanian teaches wherein the second chemistry is selective to etch the metal mask layer stronger than the passivation layer (the passivation layer is etched more slowly than the tungsten-containing layer; claim 11; see also paragraph [0015], teaching that sidewalls having the passivation layer are etched more slowly than the open front of the tungsten feature).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to further modify the method of modified Yoon such that the second chemistry selectively etches the metal mask layer stronger than the passivation layer as taught by Subramanian because Subramanian teaches that the slower etching of the passivated sidewalls allows the passivation layer to protect the sidewalls while the exposed tungsten is etched to deepen the feature, and use of a known technique to improve similar methods in the same way is obvious, see MPEP 2141 III(C).
Claim 16 is rejected under 35 U.S.C. 103 as being unpatentable over Yoon et al. in view of Wu et al. and Shaw et al., as applied to claim 12 above, and further in view of Louro and Cavaleiro, Hardness versus structure in W-Si-N sputtered coatings, Surface and Coatings Technology, Vols. 116–119, pp. 74–80 (1999).
Regarding claim 16, modified Yoon teaches the limitations of claim 12 as discussed above.
Modified Yoon does not expressly teach wherein the metal mask layer contains 59–63% tungsten, 21–25% silicon, and 14–18% nitrogen.
Louro teaches sputtered W-Si-N films in which the relative amounts of tungsten, silicon, and nitrogen are controlled by the sputtering conditions. In particular, for films deposited using 12 silicon pieces, Louro teaches a W69.2Si22.6N8.2 composition at an N2/Ar partial-pressure ratio of 1/8 and a W53.8Si24.2N22.0 composition at an N2/Ar partial-pressure ratio of 1/6.5, such that the silicon content of both compositions is within the claimed 21–25 at.% range while the tungsten and nitrogen contents lie on opposite sides of the claimed 59–63 at.% tungsten and 14–18 at.% nitrogen ranges (Table 2, p. 77).
Louro further teaches that, independent of the silicon content in the target, increasing the N2/Ar partial-pressure ratio increases the nitrogen content incorporated into the W-Si-N film, and that the relative silicon and nitrogen contents affect the resulting film structure and hardness (pp. 76–80). In particular, Louro evaluates hardness as a function of nitrogen content and teaches that changes in silicon content and the resulting film structure are associated with changes in hardness, including increased hardness with increasing silicon content for the crystalline films and different hardness behavior between crystalline and amorphous W-Si-N films (Fig. 6, p. 79; Table 3 and Conclusions, p. 80).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to further modify the WSiN metal mask layer of modified Yoon to have tungsten, silicon, and nitrogen contents within the claimed ranges by optimizing the relative W/Si/N composition through adjustment of the N2/Ar partial-pressure ratio as taught by Louro because Louro teaches that the nitrogen partial-pressure ratio controls the nitrogen content of the W-Si-N film and that the relative Si and N contents affect the resulting film structure and hardness. Thus, the relative W/Si/N composition was recognized as affecting a result of the film, and discovering optimum or workable ranges of a result-effective variable by routine experimentation is ordinarily obvious, see MPEP § 2144.05(II)(B).
Claim 17 is rejected under 35 U.S.C. 103 as being unpatentable over Yoon et al. in view of Wu et al. and Shaw et al., as applied to claim 12 above, and further in view of Ferreira et al. (Influence of Heat Treatment on the Structure of W-Si-N Sputtered Films, Key Engineering Materials, Vols. 230–232, pp. 640–643 (2002)).
Regarding claim 17, modified Yoon teaches the limitations of claim 12 as discussed above.
Modified Yoon does not expressly teach wherein the metal mask layer contains 61–65% tungsten, 9–13% silicon, and 23–27% nitrogen.
Ferreira teaches wherein a W-Si-N layer contains 61–65% tungsten, 9–13% silicon, and 23–27% nitrogen (a sputter-deposited W-Si-N film has a composition of W64Si9N27, corresponding to 64 at.% tungsten, 9 at.% silicon, and 27 at.% nitrogen; p. 640; see also pp. 642–643 and Fig. 4).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to further modify the method of modified Yoon such that the WSiN metal mask layer contains 64% tungsten, 9% silicon, and 27% nitrogen as taught by Ferreira because Ferreira teaches W64Si9N27 as a known sputter-deposited W-Si-N film composition and teaches that the structure of W-Si-N films depends on their chemical composition. Thus, using Ferreira’s known W-Si-N composition for the WSiN hard mask taught by Wu would have predictably provided a WSiN layer having a known and characterized composition, and combining prior art elements according to known methods to yield predictable results is obvious, see MPEP 2141 III(A).
Claims 19-20 are rejected under 35 U.S.C. 103 as being unpatentable over Yoon et al. (US 2016/0314981 A1) in view of Wu et al. (US 2006/0006545 A1) and further in view of Shaw et al. (US 2022/0068661 A1).
Regarding claim 19, Yoon teaches providing a substrate having a first intermediate structure of a metal hard mask structure formed over the substrate, wherein the first intermediate structure includes a metal mask layer and a first mask layer formed over the metal mask layer (metal layer 12 is formed over lower layer 11 and mask layer 13 is formed over metal layer 12, wherein the resulting vertical metal pattern is usable as a mask pattern for subsequently patterning an underlying layer; paragraphs [0049]-[0050], [0083]-[0084]).
Yoon teaches wherein the first mask layer of the first intermediate structure is patterned to have holes through the first mask layer and partially into the metal mask layer (mask layer 13 includes opening 17 and is used as an etch mask to etch metal layer 12, thereby forming hole 18 having a first depth within metal layer 12; paragraphs [0050], [0052]-[0054]).
Yoon teaches passivating first exposed surfaces of the metal mask layer in the holes using a first chemistry to form first passivation layers on the first exposed surfaces of the metal mask layer (first passivation layer 15a is formed over the inner surface of hole 18 by an oxidation plasma process, wherein hydrogen may be included in the plasma to adjust the oxidation rate; paragraphs [0056], [0063]).
Yoon teaches performing a first anisotropic etch with a second chemistry to remove first passivation portions of the first passivation layers and first metal portions of the metal mask layer at first bottoms of the holes to form first hole depths of the holes in the metal mask layer, wherein second passivation portions of the first passivation layers remain on at least part of sidewalls of the holes after the first anisotropic etch, to form a second intermediate structure of the metal hard mask structure (the chlorine-based plasma etch removes passivation layer 15a from the floor of hole 18 to expose and etch metal layer 12, while passivation layer 15a remains on the inner sidewall, thereby increasing the hole depth while preventing lateral etching of the sidewall; paragraphs [0057]-[0058], [0062]).
Yoon further teaches wherein the second chemistry is formed by flowing a second gas mixture containing BCl3 and Cl2 (the chlorine-based etch chemistry includes Cl2 and BCl3, wherein BCl3 may be added to the chlorine-containing etch gas to adjust the etch rate; paragraphs [0053], [0064]).
Yoon does not expressly teach wherein the metal mask layer contains W(Si)N.
Wu teaches wherein the metal mask layer contains W(Si)N (tungsten silicon nitride, WSiN, is taught as a material suitable for a semiconductor hardmask layer; paragraph [0029]).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify the method of Yoon to include a metal mask layer containing WSiN as taught by Wu because Wu teaches WSiN as a known material suitable for use as a semiconductor hardmask layer, and simple substitution of one known hardmask material for another to obtain predictable results is obvious, see MPEP 2141 III(B).
Modified Yoon does not expressly teach wherein the first chemistry is formed by flowing a first gas mixture containing SO2 and H2. Modified Yoon teaches H2 in the first chemistry as discussed above, however does not expressly teach including SO2 in the first chemistry.
Shaw teaches the first chemistry is formed by flowing a first gas mixture containing SO2 (SO2 is used as a passivation gas to form a passivation layer on exposed sidewalls of a metal-containing layer and thereby reduce undercut and bowing during subsequent anisotropic metal etching; paragraphs [0070], [0072]-[0074]).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to further modify modified Yoon to include SO2 in the H2-containing first chemistry as taught by Shaw because Shaw teaches SO2 as a metal-sidewall passivation gas for reducing undercut and bowing and maintaining the sidewall profile during subsequent metal etching, and use of a known technique to improve similar methods in the same way is obvious, see MPEP 2141 III(C).
Regarding claim 20, modified Yoon teaches the limitations of claim 19 as discussed above.
Modified Yoon further teaches passivating second exposed surfaces of the metal mask layer in the holes of the second intermediate structure using the first chemistry to form second passivation layers on the second exposed surfaces of the metal mask layer (after the hole has been etched to second depth D2, second passivation layer 15b is formed by the oxidation plasma process on the inner surface of hole 18, including second floor surface 19b; paragraphs [0058]-[0060]).
Modified Yoon further teaches performing a second anisotropic etch with the second chemistry to remove third passivation portions of the second passivation layers and second metal portions of the metal mask layer at second bottoms of the holes to form second hole depths of the holes in the metal mask layer (the oxidation and etch processes are repeatedly performed, whereby the passivation covering the floor is removed and the exposed metal layer is further etched such that hole 18 is increased from second depth D2 to third depth D3; paragraphs [0061]-[0062]).
Modified Yoon further teaches wherein fourth passivation portions of the second passivation layers remain on at least part of the sidewalls of the holes after the second anisotropic etch, to form a third intermediate structure of the metal hard mask structure (the cyclic process repeats the previously described passivation and etch sequence in which passivation remains on the inner sidewall while passivation at the floor is removed and the metal layer is vertically etched; paragraphs [0057]-[0058], [0061]-[0062]).
Modified Yoon further teaches wherein the second hole depths of the third intermediate structure are greater than the first hole depths of the second intermediate structure (repeated performance of the oxidation and etch processes further etches hole 18 from second depth D2 to third depth D3, wherein D3 is greater than D2; paragraph [0061]).
Conclusion
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/JONATHAN L CARTER/Examiner, Art Unit 1713
/ERIN F BERGNER/Primary Examiner, Art Unit 1713
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