DETAILED ACTION
Table of Contents
I. Notice of Pre-AIA or AIA Status 3
II. Claim Rejections - 35 USC § 103 3
A. Claims 1-4 and 6-8 are rejected under 35 U.S.C. 103 as being unpatentable US 2021/0313192 (“Joy”) in view of US 2016/0196985 (“Tan”). 3
III. Allowable Subject Matter 10
IV. Response to Arguments 12
Conclusion 15
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I. Notice of Pre-AIA or AIA Status
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
II. Claim Rejections - 35 USC § 103
In the event the determination of the status of the application as subject to AIA 35 U.S.C. 102 and 103 (or as subject to pre-AIA 35 U.S.C. 102 and 103) is incorrect, any correction of the statutory basis for the rejection will not be considered a new ground of rejection if the prior art relied upon, and the rationale supporting the rejection, would be the same under either status.
The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action:
A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102 of this title, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made.
A. Claims 1-4 and 6-8 are rejected under 35 U.S.C. 103 as being unpatentable US 2021/0313192 (“Joy”) in view of US 2016/0196985 (“Tan”).
The applied reference, Joy, has a common Assignee with the Instant Application. Based upon the earlier effectively filed date of the reference, it constitutes prior art under 35 U.S.C. 102(a)(2). This rejection under 35 U.S.C. 102(a)(2) might be overcome by: (1) a showing under 37 CFR 1.130(a) that the subject matter disclosed in the reference was obtained directly or indirectly from the inventor or a joint inventor of this application and is thus not prior art in accordance with 35 U.S.C. 102(b)(2)(A); (2) a showing under 37 CFR 1.130(b) of a prior public disclosure under 35 U.S.C. 102(b)(2)(B) if the same invention is not being claimed; or (3) a statement pursuant to 35 U.S.C. 102(b)(2)(C) establishing that, not later than the effective filing date of the claimed invention, the subject matter disclosed in the reference and the claimed invention were either owned by the same person or subject to an obligation of assignment to the same person or subject to a joint research agreement.
In addition to including any one of the statements pursuant to 35 U.S.C. 102(b)(2)(A) through (C), (supra), to overcome Joy as prior art available under 35 USC 102(a)(2), it is still applicable as prior art under 35 U.S.C. 102(a)(1) that cannot be excepted under 35 U.S.C. 102(b)(2)(C). In this instance, Applicant may rely on the exception under 35 U.S.C. 102(b)(1)(A) to overcome this rejection under 35 U.S.C. 102(a)(1) by a showing under 37 CFR 1.130(a) that the subject matter disclosed in the reference was obtained directly or indirectly from the inventor or a joint inventor of this application, and is therefore not prior art under 35 U.S.C. 102(a)(1). Alternatively, Applicant may rely on the exception under 35 U.S.C. 102(b)(1)(B) by providing evidence of a prior public disclosure via an affidavit or declaration under 37 CFR 1.130(b).
Turning now to the rejection …
Claim 1 reads,
1. (Previously Presented) A substrate processing method comprising:
[1] providing a substrate containing an etch mask over a metallic molybdenum layer in a recessed feature;
[2] exposing the substrate to a plasma-excited deposition gas that forms an etch protection layer on a sidewall of the recessed feature; and
[3] exposing the substrate to a plasma-excited etching gas that etches the metallic molybdenum layer according to the etch mask,
[4a] wherein the exposing steps are alternatingly performed a plurality of times by
[4b] stopping the exposing to the plasma-excited deposition gas and exposing to the plasma-excited etching gas and
[4c] stopping the plasma-excited etching gas to expose to the plasma-excited deposition gas
[4d] so as to temporally separate the exposure to the plasma-excited deposition gas from the exposure to the plasma-excited etching gas,
[5] wherein the plasma-excited deposition gas comprises a fluorocarbon (CxFy), or a hydrofluorocarbon (CxHyFz), and
[6] wherein the plasma-excited etching gas comprises a halogen-containing gas.
With regard to claim 1, Joy discloses,
1. (Previously Presented) A substrate processing method [¶ 18] comprising:
[1] providing a substrate 102 [¶¶ 20, 62] containing an etch mask 114/116 [¶¶ 58, 60] over a metallic molybdenum layer 106 [¶¶ 6, 16, 49, 59] in a recessed feature [i.e. the opening in mask 114/116 shown in Fig. 6B but not given a reference character];
[2] exposing the substrate 102 to a plasma-excited deposition gas [i.e. “passivant gas 140” in plasma indicated at plasma-on-and-sustained line 132 in Fig. 3A (¶¶ 27, 29, 39)] that forms an etch protection layer on a sidewall of the recessed feature [¶ 31: “A passivant gas 140 including sulfur forms a passivating layer on the vertical sidewalls and blocks lateral etching.” Also ¶¶ 32-42; Figs. 4A-4H]; and
[3] exposing the substrate 102 to a plasma-excited 132 etching gas 134, 136, 138 [¶ 37; Fig. 3A] that etches the metallic molybdenum layer 106 according to the etch mask 114/116 [¶¶ 26, 37; Figs. 3A, 6B-6C],
[4a] wherein the exposing steps are alternatingly performed a plurality of times [¶¶ 35-42; Figs. 3A and 4A-4H] by
[4b] stopping the exposing to the plasma-excited deposition gas [i.e. because the deposition gas is pulsed as shown in Figs. 3A and 4A-4H thereby stopping occurs between pulses of the deposition gas] and exposing to the plasma-excited etching gas and
[4c]-[4d] … [not taught] …
[5] … [not taught] …
[6] wherein the plasma-excited etching gas comprises a halogen-containing gas [e.g. “for etching other metals such as molybdenum, the reactant gas 134 may include a chlorine based chemistry although some oxygen may also be included” (¶ 26); also ¶ 37].
With regard to features [2]-[4b] of claim 1, Joy sates,
[0031] A passivant gas 140 including sulfur forms a passivating layer on the vertical sidewalls and blocks lateral etching. The passivating layer also forms on the horizontal surface being etched, but does not stop etching in the vertical direction due to the continuous bombardment of energetic ions. Example passivant gases including sulfur may include SO2, SF6, SO, COS, and H2S.
[0035] Another way to control the amount of the passivant gas 140 entering the plasma processing chamber is to change the flow of the passivant gas 140 with time. For example, pulsing or intermittently flowing the passivant gas 140 effectively reduces the total amount of passivant gas 140 entering the chamber during the etching process while still providing a concentration in the plasma sufficient to form passivation during the pulses.
[0036] Introducing the passivant gas 140 into the plasma processing chamber by pulsing is illustrated in FIG. 3A and is described in the flow diagram in FIG. 3B.
[0041] As illustrated in FIGS. 4A-4H, in alternative embodiments, the passivant gas may be introduced as periodic pulses (e.g., square pulses 160 in FIG. 4A, rectangular in FIG. 4E, saw tooth in FIG. 4C, triangular in FIG. 4F, and sinusoidal in FIG. 4G.
(Joy: ¶¶ 31, 35, 36, 41; emphasis added)
Thus, the deposition of the passivant layer formed by the plasma excited passivant gas 140 formed on the sidewalls and bottom, i.e. “horizontal” surface of the etched Mo layer 106 occurs only during the on pulses of the passivant gas 140 shown in Figs. 3A and 4A-4H, while pure etching with the etchant gas mixture 134, 136, 138 of both the passivant layer—particularly on the bottom/horizontal surface of the Mo layer 106—occurs during the off phase of the passivant gas 140 pulse. Thus the processes of deposition and etching are alternated, as required by feature [4a] of claim 1.
With regard to features [4b]-[4d] and [5] of claim 1 and claims 2-4,
[4c] stopping the plasma-excited etching gas to expose to the plasma-excited deposition gas
[4d] so as to temporally separate the exposure to the plasma-excited deposition gas from the exposure to the plasma-excited etching gas
[5] wherein the plasma-excited deposition gas comprises a fluorocarbon (CxFy), or a hydrofluorocarbon (CxHyFz), and
2. (Previously Presented) The method of claim 1, wherein a ratio of carbon to fluorine atoms greater than 1/4 and less than or equal to 1.
3. (Original) The method of claim 1, wherein the plasma-excited deposition gas includes a sulfur-containing gas.
4. (Original) The method of claim 3, wherein the sulfur-containing gas comprises SO2 or COS gas.
Joy does not teach that the “plasma-excited etching gas” is stopped during the depositing of the passivating layer, i.e. during the “exposing to the plasma-excited deposition gas”, such that the depositing is temporally separated from the etching, as required by features [4c] and [4d]. In addition, Joy does not teach fluorocarbons or hydrofluorocarbons is included along with the sulfur-containing gas, e.g. SO2 or COS, to form the protective layer, as required by feature [5] and claims 2-4.
Tan and Joy are drawn to the same endeavor of patterning a metal layer 101, albeit tungsten versus molybdenum, by cyclically (1) etching the metal layer 101 through an opening in a mask 103 and (2) forming a protective layer a protective layer 109 on the sidewalls and bottom of the recess 105 etched in the metal layer 101, in order to form a more uniform sidewall (Tan: Figs. 1 and 2A-2E; ¶¶ 28-39). Also like Joy (¶¶ 26, 37), Tan uses plasma-excited chlorine (Cl2) to etch the metal layer (Tan: ¶¶ 30, 31, 35). Still further like Joy, Tan may include a sulfur-containing gas, e.g. SO2 and COS, to form the protective layer 109 (Tan: ¶ 32).
With regard to claims 1-4, Tan discloses,
1. (Previously Presented) A substrate processing method comprising:
[1] providing a substrate [not shown in Fig. 2 of Tan, but “placing a substrate containing a tungsten layer [101] into a process chamber” (Tan: ¶ 29); also step 101 in Fig. 1] containing an etch mask 103 over a metallic …[tungsten]… layer 101 in a recessed feature 105 [Tan: ¶¶ 29-30; Figs. 1 and 2A];
[2] exposing the substrate to a plasma-excited deposition gas [e.g. COS and a hydrofluorocarbon such as CH3F (Tan: ¶ 32)] that forms an etch protection layer 109 on a sidewall of the recessed feature 105 [Tan: ¶¶ 29-32; step 105 in Fig. 1 and Figs. 2C, 2E]; and
[3] exposing the substrate to a plasma-excited etching gas [“Cl2 in a plasma”; step 103 in Fig. 1] that etches the metallic …[tungsten]… layer 101 according to the etch mask 103 [Figs. 2B and 2D; Tan: ¶¶ 30, 31, 34, 35],
[4a] wherein the exposing steps are alternatingly performed a plurality of times [as shown in Figs. 1 and 2B-2E; Tan: ¶¶ 34, 38] by
[4b] stopping the exposing to the plasma-excited deposition gas [Tan: ¶¶ 32-34] and exposing to the plasma-excited etching gas [Tan: ¶ 35], and
[4c] stopping the plasma-excited etching gas [Tan: ¶¶ 31, 35] to expose to the plasma-excited deposition gas [Tan: ¶ 34]
[4d] so as to temporally separate the exposure to the plasma-excited deposition gas from the exposure to the plasma-excited etching gas [because the etching gas is purged after each of the etching steps (Tan: ¶¶ 31, 35) and the plasma-excited deposition gas including oxygen radicals is purged after each formation of the protective layer 109 (Tan: ¶ 34)],
[5] wherein the plasma-excited deposition gas comprises a fluorocarbon (CxFy), or a hydrofluorocarbon (CxHyFz) [Tan: ¶ 32: “In some embodiments a hydrofluoro-carbon, such as CH3F is added to the second process gas. Preferably, the flow rate ratio of hydrofluorocarbon flow to the source of oxygen radicals flow is less than about 1 to 10.”], and
[6] wherein the plasma-excited etching gas comprises a halogen-containing gas [Cl2; Tan: ¶ 35].
2. (Previously Presented) The method of claim 1, wherein a ratio of carbon to fluorine atoms greater than 1/4 and less than or equal to 1 [e.g. CH3F; Tan: ¶ 32].
3. (Original) The method of claim 1, wherein the plasma-excited deposition gas 140 includes a sulfur-containing gas [Tan: ¶ 32].
4. (Original) The method of claim 3, wherein the sulfur-containing gas comprises SO2 or COS gas [Tan: ¶ 32].
It would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, to perform, in sequence (1) the passivation/protective layer formation step, (2) the breakthrough etch, and (3) the Mo metal etching step in entirely separate steps and in repeated cycles in Joy, as taught in Figs. 1 and 2A-2E of Tan, because it would be the substitution of one known sequence of cyclically performing the process steps of metal etching and sidewall passivation with another known sequence, which results in the same expected result of forming a more uniformly vertical metal sidewall by preventing horizontal etching of the sidewalls in the recess, as taught in each of Joy (¶¶ 16, 40, 57, 72) and Tan (¶ 2 and last sentence of ¶ 30). (See MPEP 2143.)
Further in this regard, it has been held that the selection of any order of performing process steps is prima facie obvious in the absence of new or unexpected results. See In re Burhans, 154 F.2d 690, 69 USPQ 330 (CCPA 1946). As such, the pulsing of the etching gases of Joy, in alternation with the already pulsed deposition gases, to temporally space the deposition gas pulses from the etching gas pulses, as taught by Tan, is an obvious sequence variation.
There is a reasonable expectation of success because Joy and Tan use some of the same metal etchant (i.e. halogen-containing etchants, e.g. Cl2 [Joy at ¶¶ 26, 37 and Tan at abstract, ¶¶ 30, 31, 35]) and because each of W and Mo are group VIa metals in the Periodic Table of the Chemical Elements and would be expected to demonstrate similar behavior to the etching gases and materials used to form the passivation layers.
In addition, inasmuch as Joy uses the same sulfur- and oxygen-containing gases, e.g. SO2 or COS, as those in Tan that may be used to form the passivation layer in the recess etched in the metal layer, it would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, to use SO2 or COS along with a hydrofluorocarbon, e.g. CH3F, as the passivant gas 140 to form the passivant layer of Joy, because it would be the substitution of one known passivant gas for another known passivant gas used for the same purpose of forming a passivation layer on a metal layer being etched to gain a more uniform sidewall. As such, the inclusion of a hydrofluorocarbon, e.g. CH3F, along with SO2 or COS amounts to obvious material choice. (See MPEP 2144.07.)
This is all of the features of claim 1.
With regard to claims 6-8, Joy further discloses,
6. (Currently Amended) The method of claim 5, wherein the halogen-containing gas comprises Cl2, CCl4, or BCl3 gas [Joy: ¶ 37].
7. (Previously Presented) The method of claim 5, wherein the plasma-excited etching gas 134, 136, 138 further comprises an oxygen-containing gas 134 [Joy: ¶ 37].
8. (Previously Presented) The method of claim 5, wherein the plasma-excited etching gas further comprises argon gas [Joy: ¶ 37].
III. Allowable Subject Matter
Claims 9-19 are allowed. The reasons for finding claims 9-19 allowable are explained in the Final Rejection mailed 01/16/2026 at pages 11-12.
As repeated from the Non-Final Rejection mailed 01/16/2026, claim 20 is objected to as being dependent upon a rejected base claim, but would be allowable if rewritten in independent form including all of the limitations of the base claim and any intervening claims.
The following is a statement of reasons for the indication of allowable subject matter:
Claim 20 reads,
20. (Previously Presented) The method of claim 1,
[1] wherein the exposing to the plasma-excited deposition gas and exposing to the plasma-excited etching gas are both performed in a processing chamber, and
[2] wherein the method further comprises: after the exposing to the plasma-excited deposition gas and before the exposing to the plasma-excited etching gas, performing a chamber pre-coat step, the chamber pre-coat step depositing a coating on the walls of the processing chamber.
Neither of Joy and Tan teaches a chamber coating step.
US 2003/0013314 (“Ying”), like each of Joy and Tan teaches a plasma etching process of metals. Ying teaches that it is known to coat a chamber wall after an etching step in a process call “seasoning” to trap etched metal in a carbon-containing or silicon-containing matrix (Ying: ¶¶ 55-92). However, even if Ying were combined with, e.g. Joy, Ying does not teach the claimed sequence required in feature [2] of claim 20.
Thus, the prior art does not reasonably teach or suggest—in the context of claim 20—the step of “after the depositing and before the exposing, performing a chamber pre-coat step, the chamber pre-coat step depositing a coating on the walls of the processing chamber”.
Claim 21 is objected to as being dependent upon a rejected base claim, but would be allowable if rewritten in independent form including all of the limitations of the base claim and any intervening claims.
The following is a statement of reasons for the indication of allowable subject matter:
Claim 21 reads,
21. (New) The method of claim 1, wherein the halogen-containing gas comprises F2, CF4, NF3, SF6.
The prior art does not reasonably teach or suggest—in the context of the claims—the claimed halogen-containing gases, as each of Joy and Tan uses chlorine-based plasma etch chemistry.
IV. Response to Arguments
Applicant’s arguments filed 05/19/2026 have been fully considered but they are not persuasive.
Applicant argues that “Tan’s tungsten etch chemistry does not apply to molybdenum” because the passivation chemistry in Tan depends on forming a passivation layer containing WOx and WClOx on the sidewalls that survives Cl2 plasma etch while, by contrast, MoO3 is significantly more volatile than WO3 and “would not survive the subsequent etch step on the sidewalls as Tan requires” (Remarks filed 04/16/2026: pp. 6-7). While Examiner agrees that it is known that MoO3 is more volatile than WO3, respectfully, Applicant fails to address the rest of chemistry. While Tan may use O2, O3, or CO2 as a source of oxygen to form the passivating layer 109 containing WOx (Tan: ¶¶ 32-33), as explained in the Non-Final Rejection mailed 01/16/2026, and repeated above, Tan also uses SO2 or COS as the source of oxygen radicals (id.)—which are two of the same sulfur-containing gases used in Joy to form the passivating layer containing sulfur (Joy: ¶ 31); therefore, both Joy and Tan will necessarily produce a passivating layer including the corresponding metal compounds including each of O and S, and in the case of COS, also C. This point, Applicant notably failed to address. Thus, while Tan may focus on the oxide of the tungsten as the passivation layer, and Joy may focus on the sulfur in the passivating layer, the passivating layers in each of Joy and Tan will necessarily include S, O, and C compounds of W or Mo, respectively, when SO2 or COS is used.
And even though Tan focuses on the source of oxygen radicals to produce the passivating layer, Tan may also include a “hydrofluorocarbon, such as CH3F” (infra)—which is not an oxygen source—that will result in a fluoropolymer in the passivating layer, as is well known in the art. As quoted from Tan in the rejection, Tan states,
In some embodiments a hydrofluorocarbon, such as CH3F is added to the second process gas. Preferably, the flow rate ratio of hydrofluorocarbon flow to the source of oxygen radicals flow is less than about 1 to 10.
(Tan: ¶ 32; emphasis added)
Therefore, in addition, to including at least the MoS and MoOx compounds in the passivating layer in Joy, Joy modified according to Tan to include a hydrofluorocarbon, such as CH3F, there will also be fluoropolymer. As such, Examiner finds Applicant’s conclusion that the MoO3 in the passivating layer in Joy “would not survive the subsequent etch step on the sidewalls as Tan requires” (again Remarks: pp. 6-7), even if true, would not eliminate the other components of the passivating layer, i.e. MoS and fluoropolymer, which include molybdenum and sulfur, as Joy explicitly states (as also previously quoted in the rejection):
A passivant gas 140 including sulfur forms a passivating layer on the vertical sidewalls and blocks lateral etching.
(Joy: ¶ 31; emphasis added)
Moreover, the etching would not entirely remove the additional fluoropolymer in the passivating layer of Joy, modified by Tan to include a hydrofluorocarbon, such as CH3F, along with the SO2 or COS that both Joy and Tan already use to form the respective passivating layers on the sidewalls of the Mo or W, respectively.
Based on the foregoing, Applicant’s argument it this aspect, are not found persuasive.
With regard to Applicant’s comments on In re Burhans (Remarks: p. 7), whether or not Burhans applied, it was not the primary reason for making the combination. Examiner respectfully maintains that the reason provided in the rejection for separating (1) the passivation/protective layer formation step, (2) the breakthrough etch, and (3) the Mo metal etching step is proper, even, arguendo, In re Burhans were to not apply.
Finally, Applicant argues that “[t]he Office has not identified any deficiency in Joy’s approach that would motivate a POSITA to look to Tan” (Remarks: p. 8). Examiner respectfully submits that there is no requirement to find a “deficiency” in one reference, in order to make a proper obviousness-type rejection and refers Applicant to MPEP 2143 for various rationales for combining references. Among said rationales, is the substitution of one known process sequence for another known process sequence for performing the same process of etching a refractory metal in the same family in periodic table, as explained in the rejection.
Examiner finally notes that Tan discloses all of the limitations of at least instant claims 1 through 4 except that the metal being etching is tungsten instead of molybdenum. In effect, the Instant Application merely follows the suggestion of the prior art process for etching a metal, that happens to be tungsten, and applies it, instead, to another refractory metal in the same family of the periodic table, i.e. molybdenum. Examiner respectfully maintains that this is not a novel and non-obvious process simply because the Instant Application applied a known etching process to a different metal in the same family of the periodic table. Without more, e.g., the subject matter indicated to be allowable, supra, Examiner finds claim 1, as currently drafted, to be insufficiently distinct from the prior art to be found non-obvious within the meaning of 35 USC 103.
Conclusion
THIS ACTION IS MADE FINAL. See MPEP § 706.07(a). Applicant is reminded of the extension of time policy as set forth in 37 CFR 1.136(a).
A shortened statutory period for reply to this final action is set to expire THREE MONTHS from the mailing date of this action. In the event a first reply is filed within TWO MONTHS of the mailing date of this final action and the advisory action is not mailed until after the end of the THREE-MONTH shortened statutory period, then the shortened statutory period will expire on the date the advisory action is mailed, and any extension fee pursuant to 37 CFR 1.136(a) will be calculated from the mailing date of the advisory action. In no event, however, will the statutory period for reply expire later than SIX MONTHS from the date of this final action.
Any inquiry concerning this communication or earlier communications from the examiner should be directed to ERIK KIELIN whose telephone number is (571)272-1693. The examiner can normally be reached Mon-Fri: 10:00 AM-7:00 PM.
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If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Wael Fahmy can be reached on 571-272-1705. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300.
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Signed,
/ERIK KIELIN/
Primary Examiner, Art Unit 2814
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