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 .
Response to Arguments
Applicant’s arguments, see page 5, filed 4 February 2026, with respect to the rejection of claim 3 under 35 U.S.C. 112(b) have been fully considered and are persuasive. The claim 3 under 35 U.S.C. 112(b) has been withdrawn.
Applicant has amended claim 3 to further clarify the claim language. The amended claim language is no longer considered to be indefinite. Therefore, the rejection of claim 3 under 35 U.S.C. 112(b) has been withdrawn.
Applicant's arguments filed 4 February 2026, with regards to the prior art rejections, have been fully considered but they are not persuasive.
In response to the non-final rejection filed 6 November 2025, the Applicant has amended claim 3 to overcome the rejection under 35 U.S.C. 112(b). However, no other claim amendments have been made. Applicant argues that the previous rejection of claim 1 under 35 U.S.C. 103 as being unpatentable over Hamamoto should be withdrawn due to Hamamoto failing to anticipate or render obvious the claimed invention. In particular, Applicant argues that whilst Hamamoto teaches possible tantalum-based conductive film materials such as TaN, TaO, TaON, TaB, TaBN, TaBO, TaBON, TaSi, TaSiN, TaSiO, and TaSiON, one having ordinary skill in the art would not find it obvious to replace TaBN with TaSiN, citing such a substitution as an arbitrary choice. However, MPEP 2143 I. B. states that simple substitution of one known element for another to obtain predictable results is a valid rationale to establish prima facie obviousness. See also MPEP 2144.06 II. In this case, Hamamoto teaches that TaBN and TaSiN are suitable equivalents for the purpose of use in a conductive back layer, and thus one having ordinary skill in the art would find that the proposed substitution would produce predictable results. Therefore, this argument is not found to be persuasive.
The Applicant further argues that a material’s suitability for the same general purpose does not establish that compositional constraints or elemental proportion relationships are interchangeable. Hamamoto teaches that TaBN is preferable for use as the conductive film due to wear resistance and chemical resistance (Hamamoto, paragraph 0141), which is why paragraph 0142 of Hamamoto teaches the contents of Ta, B, and N. The Applicant notes that boron (B) and silicon (Si) have different atomic size, bonding characteristic, and are not from the same periodic group. Whilst these points are not disputed by the Examiner, the Examiner notes that the conductive film is formed by a sputtering technique, such as ion-beam sputtering, magnetron sputtering, or the like (Hamamoto, paragraph 0136). These techniques are commonly used in the art to control the atomic content of each element in the produced film. That is to say, the produced film is not a traditional compound (as in, a compound wherein the elemental ratios are defined by the chemical formula), but more akin to an alloy. The replacement of boron with silicon is suggested by the broader disclosure of Hamamoto (see Hamamoto, paragraph 0139), and thus one having ordinary skill in the art would find it obvious to replace boron in the TaBN film with silicon to produce a TaSiN film. One having ordinary skill in the art would, based on the disclosure of Hamamoto, be guided to produce a film having the same atomic ratios, as the produced film is functionally a nitrogen-containing alloy. Per MPEP 2143 I. B., the substitution proposed is simply a like-for-like replacement of boron with silicon, and requires no additional modification of Hamamoto’s invention. Furthermore, MPEP 2143 I. E. (the “obvious to try” rationale) would also apply, as one having ordinary skill in the art would be motivated to try any of the taught conductive film materials to obtain desirable results. Therefore, this argument is not found to be persuasive as well.
Applicant proceeds to argue that the Examiner used impermissible hindsight to reject the claims in view of Hamamoto. In response to applicant's argument that the examiner's conclusion of obviousness is based upon improper hindsight reasoning, it must be recognized that any judgment on obviousness is in a sense necessarily a reconstruction based upon hindsight reasoning. But so long as it takes into account only knowledge which was within the level of ordinary skill at the time the claimed invention was made, and does not include knowledge gleaned only from the applicant's disclosure, such a reconstruction is proper. See In re McLaughlin, 443 F.2d 1392, 170 USPQ 209 (CCPA 1971). In the case of the instant application, the conductive film is defined as a layer containing tantalum (Ta), silicon (Si), and nitrogen (N), wherein the nitrogen content must fall within a certain range and the tantalum and silicon contents satisfy a ratio that falls within a certain range. The Examiner’s calculations in paragraph 11 of the non-final rejection filed 6 November 2025 demonstrate the extrema of the ranges taught by Hamamoto. For instance, the Examiner provides the case of minimum tantalum content and maximum tantalum content, based on the teachings of Hamamoto. The extreme cases provide ratios that fall within the claimed range of the ratio values. Thus, the Examiner’s calculations suggest that all cases of Hamamoto’s invention, when modified to replace boron with silicon, satisfy the tantalum/silicon ratio claimed by the Applicant. The Applicant’s disclosure was not relied upon at all for the calculations, and was only referred to in a demonstration as to how Hamamoto renders obvious the claimed invention.
Lastly, the Applicant argues that the nitrogen content taught by Hamamoto does not render obvious the nitrogen content recited by the instant claims. The range taught by Hamamoto is wider than the claimed invention, but overlap exists. Per MPEP 2144.05 I., overlapping ranges establish a prima facie case of obviousness. Per MPEP 2144.05 III. A., the prima facie obviousness can be rebutted by demonstrating the criticality of the claimed range. MPEP 716.02 refers to allegations of unexpected results. Examples 1 to 5 of the instant application suggest that the nitrogen content is related to advantageous effects observed by the Applicant, but per MPEP 716.02(d) II., to establish unexpected results over a claimed range, applicants should compare a sufficient number of tests both inside and outside the claimed range to show the criticality of the claimed range. The Applicant’s inventive examples suggest unexpected results, but insufficient data has been provided to establish that the nitrogen content between 18 atomic% and 35 atomic% provides unexpected results for all embodiments of the claimed invention. In particular, different silicon/tantalum content ratios also influence the observed effects of the conductive film, as demonstrated by the Applicant’s Example 4. The allegations of unexpected results must be commensurate in scope with the claimed invention (MPEP 716.02(d)), and thus evidence to support that the claimed nitrogen content provides the advantageous effects of the claimed invention in all embodiments (e.g. all of the silicon/tantalum ratios). If the Applicant can provide sufficient evidence to support the allegation of unexpected results, the prima facie obviousness of the nitrogen content would be considered overcome. At present though, the Applicant’s arguments are not found to be persuasive and therefore the previous prior art rejections are not withdrawn.
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.
Claim(s) 1-9 are rejected under 35 U.S.C. 103 as being unpatentable over US 20150301441 A1 (hereby referred to as Hamamoto).
Regarding Claims 1 and 4-5, Hamamoto teaches a reflective mask blank and a method for manufacturing both a reflective mask blank and a reflective mask. The reflective mask blank comprises a multilayer reflective film configured to reflect EUV light as exposure light disposed upon on a main surface of a substrate and a conductive film formed on the other main surface (also referred to as a back surface) of the substrate (Hamamoto, paragraph 0104). Refer to Fig. 1 of Hamamoto for a depiction of the mask blank. The mask blank further includes a protective film, an absorber film, and a resist film (formed in that order) disposed over the multilayer reflective film (Hamamoto, paragraph 0104). The conductive film is provided for facilitating electrostatic chucking of the reflective mask, and it is preferable that the material of the conductive film has a sheet resistance value of 100 Ω/square or less (Hamamoto, paragraph 0111). Materials containing tantalum (Ta) are preferred due to the improved wear resistance and chemical resistance of these materials (Hamamoto, paragraph 0111 and 0136-0137). The conductive film may be a single thin film or a plurality of thin films of two or more kinds of materials (Hamamoto, paragraph 0139). The suitable materials include TaSiN (tantalum silicide nitride) and TaSiON (tantalum silicide oxynitride), amongst other tantalum-containing materials (Hamamoto, paragraph 0139). The thickness of the conductive film is not particularly limited and is set within, for example, a range of 10 to 300 nm (Hamamoto, paragraph 0143). In some examples, the thickness of the conductive film was on the order of 70-80 nm (see Hamamoto, paragraph 0231 and 0238).
Hamamoto does not explicitly disclose an embodiment wherein a conductive layer containing tantalum, silicon, and nitrogen is used for the reflective mask blank.
However, Hamamoto teaches that when a conductive film of TaBN is utilized, the composition ratio is preferably such that the content of boron (B) is 5 to 25 atomic%, the content of nitrogen (N) is 5 to 40 atomic%, and the balance is tantalum (Ta) (Hamamoto, paragraph 0142). The Examiner cites this particular embodiment because TaBN and TaSiN are taught by Hamamoto to be functional equivalents for the same purpose (see Hamamoto, paragraph 0139) and because boron and silicon both fall into the class of elements known as metalloids. Therefore, it would have been obvious to one having ordinary skill in the art before the filing date of the instant application to use a TaSiN film as the conductive layer for the reflective mask taught by Hamamoto, due to Hamamoto teaching TaSiN as a suitable material. It would have been obvious to one having ordinary skill in the art before the filing date of the instant application to then provide a TaSiN film having a composition that has a ratio of the silicon content to the total content of silicon and tantalum between 3% and 50% and a nitrogen content between 18 atomic% and 35 atomic%. This feature would have been obvious to one having ordinary skill in the art because based on the composition of the TaBN film (which is a close analog to the TaSiN film because TaBN and TaSiN are taught to be equivalent for the purposes of producing conductive films and because B and Si both are metalloids), every value within the provided elemental ranges produces a ratio between 3% and 50%. For instance, when the boron is replaced with silicon, the silicon content can be present between 5 atomic% and 25 atomic%. The nitrogen content may be between 5 atomic% and 40 atomic%, and tantalum makes up the balance. Refer to paragraph 0142 of Hamamoto. When the minimum tantalum content is obtained (using 25 atomic% silicon and 40 atomic% nitrogen, yielding 35 atomic% tantalum), the ratio of silicon content with respect to the total content of silicon and tantalum is 41.7% (
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). When the maximum tantalum content is obtained (using 5 atomic% silicon and 5 atomic% nitrogen, yielding 90 atomic% tantalum), the ratio of silicon content with respect to the total content of silicon and tantalum is 5.3% (
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). Furthermore, Hamamoto teaches that nitrogen suppresses oxidation of tantalum (Hamamoto, paragraph 0140), and therefore one having ordinary skill in the art could arrive at the nitrogen content recited by instant claim 1 by routinely optimizing the range of nitrogen content taught by Hamamoto to achieve a satisfactory reduction in oxidation of the conductive film. See MPEP 2144.05 II. Thus, based on the broader disclosure of Hamamoto, one having ordinary skill in the art could reasonably arrive at a reflective mask blank having a conductive back film satisfying the criteria recited by instant claims 1 and 4-5.
Regarding Claims 2-3 and 6-7, Hamamoto renders obvious the conductive film containing tantalum, silicon, and nitrogen, as explained above. Hamamoto further teaches that the conductive layer may be formed of a plurality of thin films of two or more kinds of materials (Hamamoto, paragraph 0139). Hamamoto teaches that TaSiON (tantalum silicide oxynitride) is a suitable material for this function (Hamamoto, paragraph 0139). The thickness of the layer may be a low as 10 nm (Hamamoto, paragraph 0143). When the conductive layer contains oxygen, the oxygen content is 1 to 20 atomic% (Hamamoto, paragraph 0142). As the nitrogen content is taught to be 5 to 40 atomic% (Hamamoto, paragraph 0142), an embodiment wherein the total content of oxygen and nitrogen is 40 atomic% or more can be obtained. The overlapping ranges create a prima facie case of obviousness, per MPEP 2144.05 I. When combined with the first conductive layer (described in the preceding paragraphs of this office action), a conductive film having a first layer comprising tantalum, silicon and nitrogen (having the composition according to instant claim 2) and a second layer comprising tantalum, silicon, oxygen, and nitrogen (having the composition according to instant claim 2) is obtained.
Regarding Claim 8, Hamamoto teaches that the sheet resistance of the conductive film is 100 Ω/square or less (Hamamoto, paragraph 0111). Hamamoto does not explicitly disclose surface roughness or ΔTIR values of the conductive film. However, one having ordinary skill in the art would expect that the conductive film has the surface roughness recited by instant claim 8 due to the conductive film comprising similar or identical materials in similar or identical amounts as the back conductive film recited by instant claim 1. Per Example 1 of the instant application’s specification (refer to paragraphs 0053-0056 of the instant application’s specification), the conductive film was not subjected to additional processing and had a surface roughness of 0.22 nm (see paragraph 0056 of the instant application’s specification). As the conductive film taught by Hamamoto is produced through sputtering (Hamamoto, paragraph 0136), which is the same method used by the instant application (see paragraph 0053 of the instant application’s specification), it would be expected by one having ordinary skill in the art that the conductive film of Hamamoto has similar or identical surface roughness properties as the conductive film of the instant application. Furthermore, Hamamoto teaches that the stress of the conductive film is suppressed, thus reducing the tendency of the conductive film to undergo a change in flatness with respect to time (Hamamoto, paragraph 0192-0194). As the film is compositionally similar or identical to that of the instant application, it would then be expected by one having ordinary skill in the art that the extent of warping is within the range recited by instant claim 8.
Regarding Claim 9, Hamamoto teaches that the reflective mask blank is used to produce a reflective mask by subjecting the resist film to a desired electron beam writing and development, thereby forming a resist pattern (Hamamoto, paragraph 0118). The resist pattern is used as a mask to etch the absorber film and form an absorber film pattern (Hamamoto, paragraph 0118).
Conclusion
THIS ACTION IS MADE FINAL. 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 nonprovisional extension fee (37 CFR 1.17(a)) 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 mailing date of this final action.
Any inquiry concerning this communication or earlier communications from the examiner should be directed to JAYSON D COSGROVE whose telephone number is (571)272-2153. The examiner can normally be reached Monday-Friday 10:00-18:00.
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/JAYSON D COSGROVE/Examiner, Art Unit 1737
/JONATHAN JOHNSON/Supervisory Patent Examiner, Art Unit 1734