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 § 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 1-20 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.
As to claims 1, 7 and 14, the limitation of “wherein a size for the sub-resolution grating lines is selected based on best focus or highest contrast across various pitches or mask features to be printed” renders the scope of the claims unclear. In particular, the terms “best focus” and “highest contrast” do not clearly identify the criterion by which the claimed size is determined. The claims do not specify the focus range, pitch range or other objective criterion over which the recited “best” focus or “highest” contrast is determined. Accordingly, the claims do not provide an objective boundary by which one of ordinary skill in the art can determine whether a particular sub-resolution grating size satisfies the limitation.
For the same reasons, the limitation of “best depth of focus” in claims 2, 9 and 15 renders the claims indefinite.
As to claims 13 and 18, it is unclear what numerical aperture values constitute the recited “hyper numerical aperture range”. The claims do not recite a numerical range or threshold distinguishing a “hyper” NA from a high, conventional or other NA range. Accordingly, the metes and bounds of the claimed “hyper numerical aperture range” cannot be determined with reasonable certainty.
For purposes of examination and application of the prior art, and without waiving the foregoing rejection, the Examiner interprets: “best focus”, “high contrast” and “best depth of focus” broadly as referring to optimization of an imaging-quality characteristic over the evaluated mask layouts and/or imaging conditions disclosed in the specification. Also, the Examiner interprets the recited “hyper numerical aperture range” broadly as encompassing a numerical aperture range that is relatively high as compared with a conventional or lower numerical aperture range applicable to the recited lithographic imaging system. This interpretation is made solely to permit examination of the claims under the broadest reasonable interpretation consistent with the specification and do not resolve the indefiniteness identified above.
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 1-20 are rejected under 35 U.S.C. 103 as being unpatentable over Lucas et al (U.S.Pat. 6,989,229 B2) in view of Cui et al (U.S.Pat. 7,018,746).
With respect to claims 1, 7 and 14 and 20, Lucas discloses a mask (18) for EUV lithography processes (see figure 2) in a high or hyper numerical range and comprising substantially all features of the instant claim such as: the mask (18) has a mask pattern (see figure 6; 20-28) according to a mask layout wherein the mask layout is a superposition of a first mask sub-layout (98; 102) having a plurality of mask features/flare proximity regions (70, 74, 78, 94) to be printed, wherein the plurality of mask features to be printed has at least one mask feature oriented along a first direction of the mask layout and a second mask layout (100) having one or more sub-resolution gratings having sub-resolution grating lines, wherein the sub-resolution grating lines extend substantially in a second direction of the mask layout and runover substantially a full width in the second direction of the mask layout, wherein the one or more sub-resolutions are not printable (81, 83, 85, 89, 91, 93) for the high or hyper numerical aperture range (see col.1, lines 40-49), wherein the mask layout is a result of overlaying the first mask sub-layout and the second mask sub-layout. Lucas further teaches that the sub-resolution features are dimensioned so as not to resolve on the wafer (W). For example: Lucas a width less than approximately : 0.3 x magnification x wavelength/numerical aperture
to prevent the feature from appearing on the target wafer (Figure 5; col.4 lines 15-26)
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However, Lucas does not expressly disclose “wherein a size for the sub-resolution grating lines in selected based on best focus or highest contrast across various pitches for mask features to be printed” as recited. In other words, Lucas lacks to teach selecting the dimensions and arrangement of the sub-resolution features by repeatedly evaluating different SRAF (Sub-Resolution Assist Feature) configurations over different feature pitches and selecting the configuration providing optimized lithographic imaging quality. Cui, however, teaches a sub-resolution assist feature design methodology in which SRAFs are added to a photomask layout and their design and placement are optimized according to lithographic imaging performance. Cui teaches that an SRAF design strategy specifies, inter alia, assist feature width, distance between an assist feature and a main feature, and the number of assist features for teach design pitch (see figure 1B; col.4, lines 7-43). Cui further teaches generating a sample design containing the design pitches for a technology node and simulating image properties for the respective design pitches using optical/resist image models (see figures 3-4, col.6, lines 4-65). Cui teaches the SRAF design strategy is optimized by taking into consideration the lithographic focus window, mask-making constraint and whether the SRAFs remain non-printing and that property positioned SRAFs are employed to optimize the overall lithographic process window.
In view of that teachings, it would have been obvious to one having ordinary skill in the art before the effective filling date of the claimed invention to employ the simulation-based SRAF design and optimization methodology taught by Cui in determining the dimensions, spacing, number, pitch-related arrangement and placement of the non-resolving diffraction/scattering feature of Lucas. One having ordinary skill in the art would have been motivated to do so because Lucas expressly seeks to improve pattern fidelity and reduce sensitivity of printed features to focus variations, while Cui teaches a known method of selecting SRAF geometries, and placement as a function of design pitches and simulated lithographic image properties in order to optimize the lithographic focus/process window. Accordingly, selection of the size and arrangement of Lucas’s sub-resolution features based upon simulated imaging performance, including focus/process window and image-intensity/contrast-related characteristics over different pitches would have been obvious to a skilled artisan.
As to claims 2, 8 and 15, Lucas in view of Cui teaches determining the dimensions and arrangement of sub-resolution assist features based upon lithographic imaging performance, as discussed above. Thus, selecting the SRAF configuration providing the best or optimized imaging quality parameters would have been obvious over Lucas in view of Cui.
Regarding claims 3-5, 9-12 and 16-19, Lucas teaches none-resolving diffraction/scattering bars positioned relative to printable mask features and dimensioned so as not to resolve in the photoresist (see figure 5, elements 81, 83, 85, 87, 89, 91, 93). Cui teaches optimizing SRAF (col.4, lines 7-33). Accordingly, selecting the spacing and orientation of such sub-resolution features relative tot he corresponding principal features according to the geometry and pitch of the printable pattern would have been obvious geometrical implementation of the known SRAF design strategy.
As to claims 6, 13, Lucas teaches an EUV projection system including reflective mask (18) and projection optical system (20-28). Cui teaches adapting SRAF dimensions and placement according to the particular feature geometry and imaging condition, including numerical aperture (see figure 4; col.6, lines 10-20). In view of such teachings, it would have been obvious to a skilled artisan to adapt the dimensions and placement of the assist features to the corresponding direction-dependent imaging characteristics in accordance with Cui’s optimization methodology.
Prior Art Made of Record
The prior art made of record and not relied upon is considered pertinent to applicant's disclosure.
Tsai et al (U.S.Pat. 8,443,312 B2); Ogadhoh (U.S.Pat. 8,399,157 B2) disclose lithographic masks and have been cited for technical background.
Any inquiry concerning this communication or earlier communications from the examiner should be directed to HUNG HENRY NGUYEN whose telephone number is (571)272-2124. The examiner can normally be reached Monday-Friday 7:00AM-4:30PM.
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If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Toan Minh Ton can be reached at 571-272-2303. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300.
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HUNG HENRY NGUYEN
Primary Examiner
Art Unit 2882
Hvn
8/14/26
/HUNG V NGUYEN/ Primary Examiner, Art Unit 2882
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