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 .
This is the initial office action for US Patent Application No. 18/614445 by Hsu et al.
Claims 1-20 are currently pending and have been fully considered.
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 1-14 and 16-20 are rejected under 35 U.S.C. 103 as being unpatentable over Hsu et al. (US 2022/0137499 A1), herein referred to as Hsu.
Regarding claims 1 and 19, Hsu teaches (Figures 1 and 2, [0016-0017], Claims 1 and 17) an extreme ultraviolet (EUV) mask and its method of forming, the EUV mask comprising a substrate 104; a reflective multilayer stack 110 on the substrate; a capping layer 120 on the multilayer stack; a buffer layer 130 on the capping layer; and a patterned absorber layer 140 on the buffer layer.
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Hsu proceeds to teach the patterned absorber layer may have a thickness ranging from about 5 nm to about 50 nm, which overlaps the thickness of the patterned absorber layer recited in claim 1 (thickness between 20-50 nanometers). Hsu further teaches [0034-0036] the patterned absorber layer includes an alloy of a first material and a second material, wherein the first material can be rhodium (Rh) having an EUV refractive index (n) and an EUV extinction coefficient (k) and wherein the second material is tantalum (Ta) which is a group 5, period 6 transition metal.
Hsu does not appear to explicitly teach the limitation recited in claims 1 and 19 of the second material having “EUV refractive index (n) greater than the EUV refractive index (n) of rhodium and an EUV extinction coefficient (k) greater than the EUV extinction coefficient (k) of rhodium.”
However, the Ta-based alloy taught by Hsu for the patterned absorber layer is considered to be obvious in view of Applicant’s specification (Pre-Grant Publication US 2025/0216764 A1, [0048]) which discloses tantalum (Ta) as being a suitable transition metal having an EUV refractive index greater than the EUV refractive index of rhodium and an EUV extinction coefficient greater than the EUV extinction coefficient of rhodium.
At the time of the filing date of the present application, it would have been obvious to one of ordinary skill in the art to construct an EUV mask with a patterned absorber layer containing rhodium (Rh) and tantalum (Ta), in view of the teachings of Hsu, in order to reduce mask shadowing effects during an EUV lithography process. Therefore, claims 1 and 19 are obvious in view of Hsu.
Regarding claim 2, Hsu teaches [0036] the second material is tantalum (Ta) which is a group 5, period 6 transition metal. Therefore, claim 2 is obvious in view of Hsu.
Regarding claims 3 and 4, Hsu teaches [0037] the Ta-based alloy for the patterned absorber layer may further include one or more interstitial elements such as boron (B), nitrogen (N) and oxygen (O). Therefore, claims 3 and 4 are obvious in view of Hsu.
Regarding claim 5, Hsu does not appear to explicitly teach the specified phase shift values recited in claim 5. However, as discussed above, Hsu teaches a Ta-based alloy for the patterned absorber layer and therefore, it would be obvious to one of ordinary skill in the art to select an alloy to provide a phase shift of between 1.17π and 1.2π based on the disclosure in Hsu. Therefore, claim 5 is obvious in view of Hsu.
Regarding claim 6, Hsu teaches [0036] an alloy of tantalum rhodium (TaRh) may be used for the patterned absorber layer. The content of rhodium in the aforementioned alloy is 50 atomic percent and falls within the range of 10 to 75 atomic percent. Therefore, claim 6 is obvious in view of Hsu.
Regarding claim 7, Hsu does not appear to explicitly teach the alloy containing 2-20 atomic percent of oxygen, nitrogen, boron or combinations thereof. However, Hsu does teach [0037] that it is desirable to dope one or more interstitial elements such as boron, nitrogen and oxygen in the alloy for the patterned absorber layer in order to improve material density and strength of the resulting alloy. Therefore, claim 7 is obvious in view of Hsu.
Regarding claims 8-10, Hsu teaches [0038] the patterned absorber layer may be configured to have a multilayer structure. It would have been obvious to one of ordinary skill in the art to form a patterned absorber layer with first and second sublayers having specified alloy compositions because applying a known technique, based on the teachings of Hsu, to achieve predictable results is considered to be a rationale for establishing a prima facie case of obviousness in view of MPEP Chapter 2143, Section I, Part D. Therefore, claims 8-10 are obvious in view of Hsu.
Regarding claim 11, Hsu teaches [0034 and 0036] rhodium may be used in the alloy for the patterned absorber layer. The refractive index and extinction coefficient properties of rhodium would therefore be similar to the properties recited in claim 11. Therefore, claim 11 is obvious in view of Hsu.
Regarding claims 12-14 and 20, Hsu teaches (Figures 1 and 2, [0016-0017], Claims 1 and 17) an extreme ultraviolet (EUV) mask and its method of forming, the EUV mask comprising a substrate 104; a reflective multilayer stack 110 on the substrate; a capping layer 120 on the multilayer stack; a buffer layer 130 on the capping layer; and a patterned absorber layer 140 on the buffer layer.
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Hsu further teaches [0034-0036] the patterned absorber layer includes an alloy of a first material and a second material, wherein the first material can be rhodium (Rh) having an EUV refractive index (n) and an EUV extinction coefficient (k) and wherein the second material is tantalum (Ta) which is a group 5, period 6 transition metal.
Hsu does not appear to explicitly teach the limitation recited in claims 12 and 20 of “in a plot of EUV refractive index (n) vs EUV extinction coefficient (k) for the first material and the second material, a line between a first material coordinate defined by the EUV refractive index (n) and the EUV extinction coefficient (k) of the first material and a second material coordinate defined by the EUV refractive index (n) and the EUV extinction coefficient (k) of the second material passes through a polygon defined in a plot of four coordinates (n, k), the four coordinates being (0.880, 0.030), (0.880, 0.050), (0.900, 0.050) and (0.900, 0.030).”
However, the Ta-based alloy taught by Hsu for the patterned absorber layer is considered to be obvious in view of Applicant’s specification (Pre-Grant Publication US 2025/0216764 A1, [0048]) which discloses tantalum (Ta) and rhodium (Rh) as being suitable metals having desirable EUV refractive index EUV extinction coefficient properties.
At the time of the filing date of the present application, it would have been obvious to one of ordinary skill in the art to construct an EUV mask with a patterned absorber layer containing rhodium (Rh) and tantalum (Ta), in view of the teachings of Hsu, in order to reduce mask shadowing effects during an EUV lithography process. Therefore, claims 12-14 and 20 are obvious in view of Hsu.
Regarding claim 16, Hsu teaches [0037] the Ta-based alloy for the patterned absorber layer may further include one or more interstitial elements such as boron (B), nitrogen (N) and oxygen (O). Therefore, claim 16 is obvious in view of Hsu.
Regarding claims 17 and 18, Hsu teaches [0038] the patterned absorber layer may be configured to have a multilayer structure. At the time of the filing date of the present application, it would have been obvious to one of ordinary skill in the art to form a patterned absorber layer with first and second sublayers having specified alloy compositions because applying a known technique, based on the teachings of Hsu, to achieve predictable results is considered to be a rationale for establishing a prima facie case of obviousness in view of MPEP Chapter 2143, Section I, Part D. Therefore, claims 17 and 18 are obvious in view of Hsu.
Claim 15 is rejected under 35 U.S.C. 103 as being unpatentable over Hsu et al. (US 2022/0137499 A1), herein referred to as Hsu, in view of Nakagawa et al. (US 2025/0370324 A1), herein referred to as Nakagawa.
Hsu does not appear to explicitly teach the limitations of claim 15 directed to the patterned absorber layer including an alloy of both rhodium (Rh) and either aluminum (Al) or tellurium (Te). However, from the same field of technology involving EUV lithography, Nakagawa recites the formation of a reflective mask.
In view of claim 15, Nakagawa teaches [0113] the absorber film of the reflective mask can be configured to include an alloy of two or more materials including rhodium (Rh), aluminum (Al) and tellurium (Te).
At the time of the filing date of the present application, it would have been obvious to one of ordinary skill in the art to modify the patterned absorber layer taught by Hsu to include the specified alloy compositions taught by Nakagawa because substituting known materials to achieve predictable results is considered to be a rationale for establishing a prima facie case of obviousness in view of MPEP Chapter 2143, Section I, Part B. Therefore, claim 15 is obvious in view of the combination of Hsu and Nakagawa.
Any inquiry concerning this communication or earlier communications from the examiner should be directed to STEWART A FRASER whose telephone number is (571)270-5126. The examiner can normally be reached M-F, 7am-4pm, EST.
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/STEWART A FRASER/Primary Examiner, Art Unit 1724
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