DETAILED ACTION
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 .
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 text of those sections of Title 35, U.S. Code not included in this action can be found in a prior Office action.
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 1-20 are rejected under 35 U.S.C. 103 as being unpatentable over Hayashi (US 2011/0200920) in view of Mikami (JP 2013122952, IDS 7/15/2022, reference citations from English translation).
Regarding Claims 1-2, 4-7, 9-12, and 14-15, Hayashi teaches a reflective mask blank for EUV lithography (abstract). Fig. 1 is a cross-sectional view of the mask blank comprising a reflective layer 12, a protection layer 13, and an absorbing layer 14 (paragraph [0050]). The substrate 11 can be a glass having low thermal expansion coefficient, specifically SiO2-TiO2 (paragraph [0052]). Furthermore, the glass preferably has a hydrogen molecule concentration of 1 x 1019 molecules/cm3 from the viewpoint of a cleaning effect of carbon contamination and a deoxization effect of an oxidized film (paragraph [0053]) (Claims 1, 6). The reflective layer 12 can achieve a high reflectivity to EUV light, such as using a Mo/Si reflective film where Mo is the high refractive index material and Si is the low refractive index material (paragraph [0063]) (Claim 2, 7, 12). The protection layer is formed using magnetron sputtering method with a Ru target and Ar gas (paragraph [0069]) (Claim 4, 9, 14). The hydrogen content in the substrate is measured using a thermal desorption spectrometer (paragraph [0054-0055]).
Hayashi is silent to the multilayer reflective film comprising hydrogen at an atomic number density of 7.0 x 10-3 atoms/nm3 or less.
However, Mikami teaches in Example 1 forming a substrate with a reflective layer for EUV lithography mask blank which has a structure shown in Fig. 1 (paragraph [0067]) comprising a TiO2-SiO2 glass substrate, a conductive backside coating, a Mo/Si multilayer reflective film that is applied using H2 has at 3 vol%, and a protective layer of Ru (paragraph [0067-0070]). The hydrogen content in the Mo/Si multilayer reflective film is between 0.2 to 10 atomic percent (at%) (paragraph [0028]). The average hydrogen content is determined by measuring the composition using an X-ray photoelectron spectrometer or a secondary ion mass spectrometer (paragraph [0029]). When the Mo/Si multilayer film contains hydrogen, isotopic shrinkage is further promoted in addition to shrinkage in the film direction due to mixing at the interface of each Mo/Si multilayer at the time of performing heat treatment (paragraph [0020]). Mikami further discloses an absorber layer over the protective layer, and forming a pattern thereon (paragraph [0033]).
Mikami further teaches the heat treatment step is sensitive to time and temperature, such that if the heat treatment temperature is higher than 160 oC, the mixing in the Mo/Si multilayer film may proceed too much (paragraph [0062]). When the heating time is shorter than 5 minutes, the stress relaxation of the film is insufficient and when the heating time is longer than 60 minutes, the mixing proceeds too much and each layer shrinks greatly, leading to reduced reflectance and peak wavelength of reflected light (paragraph [0062]).
Mikami clearly demonstrates that when the Mo/Si multilayer film mixes to a large degree, the reflectance is reduced. Thus, the mixed region of Mo/Si must have a lower reflectance than the other regions of Mo/Si individually. As such, the mixed Mo/Si film teaches that the surface reflectance of the mixed area with respect to EUV light is lower than a surface reflectance of the other area with respect to EUV light as claimed (Claims 5, 10, 11).
While the vol% of hydrogen in the sputtering gas is known, the reactivity with Mo and Si under these specific sputtering conditions are not and whether the thermal heating steps allows hydrogen to release from the substrate, so the exact amount of hydrogen incorporated into the layer in the example is not known. It is the examiner’s position that the range of hydrogen sputtering gas demonstrated in Mikami would necessarily encompass the claimed range of hydrogen atomic number density of 7.0 x 10-3 atom/nm3 or less.
Hayashi and Mikami both disclose methods of making EUV mask blanks and photomasks. It would have been obvious for one of ordinary skill in the art to have modified the Mo/Si multilayer reflective film of Hayashi with the hydrogen-containing Mo/Si multi-layer reflective film of Mikami. One of ordinary skill would have been motivated to make this modification to promote isotopic shrinkage and shrinkage in the film direction due to mixing at the interface of each Mo/Si interlayer as suggested by Mikami.
Regarding Claims 3, 8, 13, 16, and 19, the discussion of Claims 1, 6, 7 and 11, 12 are relied upon as above. Hayashi further discloses the glass preferably has a hydrogen molecule concentration of 1 x 1019 molecules/cm3 from the viewpoint of a cleaning effect of carbon contamination and a deoxization effect of an oxidized film (paragraph [0053]). Hayashi discloses measuring the hydrogen content in the substrate is measured using a thermal desorption spectrometer (paragraph [0054-0055]). Mikami discloses measuring the average hydrogen content of the Mo/Si multilayer reflective film using X-ray photoelectron spectrometer or a secondary ion mass spectrometer (paragraph [0029]).
Mikami and Hayashi disclose various methods used to explicitly measure hydrogen content in either a substrate or a multilayer reflective film. The different methods are variations on one another to perform the same hydrogen content measurement. It would have been obvious for one of ordinary skill in the art to have measured the hydrogen content of the substrate using any of the aforementioned known methods in the prior art. One of ordinary skill in the art would reasonably substitution of one expect experimental method to measure hydrogen content for another to produce the same or similar results.
Regarding Claims 17, 18, and 20, the discussion of Claims 12, 16, and 19 are relied upon as above. Hayashi further discloses the protection layer is formed using magnetron sputtering method with a Ru target and Ar gas (paragraph [0069]) (Claim 17, 20).
Mikami further teaches the heat treatment step is sensitive to time and temperature, such that if the heat treatment temperature is higher than 160 oC, the mixing in the Mo/Si multilayer film may proceed too much (paragraph [0062]). When the heating time is short than 5 minutes, the stress relaxation of the film is insufficient and when the heating time is longer than 60 minutes, the mixing proceeds too much and each layer shrinks greatly, leading to reduced reflectance and peak wavelength of reflected light (paragraph [0062]).
Mikami clearly demonstrates that when the Mo/Si multilayer film mixes to a large degree, the reflectance is reduced. Thus, the mixed region of Mo/Si must have a lower reflectance than the other regions of Mo/Si individually. As such, the mixed Mo/Si film teaches that the surface reflectance of the mixed area with respect to EUV light is lower than a surface reflectance of the other area with respect to EUV light as claimed (Claim 18).
Conclusion
Any inquiry concerning this communication or earlier communications from the examiner should be directed to KEVIN JAMES DRUMMEY whose telephone number is (703)756-5419. The examiner can normally be reached Monday - Friday 7:30am-5:00pm EST.
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If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Mark Huff can be reached at (571) 272-1385. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300.
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/K.J.D./Examiner, Art Unit 1737
/MARK F. HUFF/Supervisory Patent Examiner, Art Unit 1737
