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 .
Continued Examination Under 37 CFR 1.114
A request for continued examination under 37 CFR 1.114, including the fee set forth in 37 CFR 1.17(e), was filed in this application after final rejection. Since this application is eligible for continued examination under 37 CFR 1.114, and the fee set forth in 37 CFR 1.17(e) has been timely paid, the finality of the previous Office action has been withdrawn pursuant to 37 CFR 1.114. Applicant's submission filed on 20 July 2026 has been entered.
Response to Arguments
Applicant’s arguments, see page 7, filed 30 June 2026, with respect to the rejection(s) of claim(s) 1 and 3-21 under 35 U.S.C. 103 have been fully considered and are persuasive. Therefore, the rejection has been withdrawn. However, upon further consideration, a new ground(s) of rejection is made in view of US 20120082924 A1 (hereby referred to as Kominato).
Applicant has amended independent claims 1 and 18 to recite that the intermediate layer includes iridium (Ir). Dependent claim 3 has also been amended to recite that the intermediate layer further includes at least one element selected from the group consisting of tantalum (Ta), palladium (Pd), nickel (Ni), tin (Sn), ruthenium (Ru), and gold (Au). Applicant argues that the previously cited prior art (Ohkubo and Maeda) fails to disclose every limitation of claims 1 and 18, due to Ohkubo and Maeda failing to teach or suggest an intermediate layer including iridium (Ir). Upon review of the previously cited prior art, the Examiner agrees with the Applicant’s position, as Ohkubo and Maeda do not mention iridium. Therefore, Applicant’s arguments are found to be persuasive and the previous rejection has been withdrawn. However, a new rejection is presented in view of US 20120082924 A1 (hereby referred to as Kominato), as explained below.
Applicant has amended independent claim 11 and dependent claim 13 to include the same limitations added to independent claim 1 and dependent claim 3 mentioned above. The rejection of claims 11 and 13 now cites Kominato in the rejection as well.
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, 3-4, 6-10, 18, and 21 are rejected under 35 U.S.C. 103 as being unpatentable over US 20220043335 A1 (hereby referred to as Ohkubo) in view of US 20220252972 A1 (hereby referred to as Maeda) and US 20120082924 A1 (hereby referred to as Kominato).
Regarding Claims 1 and 18, Ohkubo discloses a mask blank, a transfer mask, and a semiconductor device manufacturing method. The transfer mask is manufactured by patterning a mask blank (Ohkubo, paragraph 0150). The mask blank (120) comprises a transparent substrate (1), an etching stopper film (2), a phase shift film (3), a hard mask film (11), and a light-shielding film (4) (Ohkubo, paragraph 0217-0231; paragraph 0144, and Fig. 7). A second hard mask (12) is disposed over the light-shielding film (see paragraph 0144 and Fig. 7 of Ohkubo). The light-shielding film (4) is considered analogous to the claimed “intermediate” film. The above-described mask blank thus comprises a multilayer structure including N-pairs of a hard mask layer and an intermediate layer on the hard mask layer, wherein N is 1 (and thus a natural number up to five). To produce the transfer mask, a resist film is formed over the mask blank, and a pattern to be formed in the light-shielding film (4) is written on the resist film with an electron beam, thus forming a resist pattern (Ohkubo, paragraph 0152 and Fig. 9A). Dry etching is carried out using a mixed gas with the resist pattern acting as an etching mask, thus forming a pattern in the second hard mask (12) (Ohkubo, paragraph 0152). The patterned second hark mask is used as an etching mask to pattern the light-shielding film (4) (Ohkubo, paragraph 0153). Additional etching is performed for the first hard mask layer (11) and the phase shift layer (3), using the patterned layer disposed over each of these layers as an etching mask (Ohkubo, paragraph 0154-0156 and Fig. 9A-9G). It is preferred that the light-shielding film (4), which is analogous to the intermediate layer of the instant application, is formed of a material containing silicon or tantalum (Ohkubo, paragraph 0144). The hard mask preferably contains chromium (Ohkubo, paragraph 0144), and therefore the light-shielding film and the hard mask are made of different materials.
However, Ohkubo fails to teach the extension of the pattern formed in the resist layer into the hard mask layer and the phase shift layer. Maeda teaches a mask blank and a phase shift mask. The mask blank comprises a substrate having a phase shift film, a light shielding film, and a hard mask formed upon it (Maeda, paragraph 0066 and Fig. 1). To convert the mask blank into a phase shift mask, a resist film is formed over the mask blank and patterned (Maeda, paragraph 0069). The pattern formed on the resist film is intended to be transfer to the phase shift film (Maeda, paragraph 0069). The pattern is transferred from the resist film to the phase shift film by etching each of the underlying layers using a dry etching technique (Maeda, paragraph 0069-0070 and Fig. 2A-2D). An additional pattern may be formed afterwards (Maeda, paragraph 0071).
However, Ohkubo and Maeda are silent in regards to an intermediate layer including iridium (Ir). Kominato teaches a mask blank and a mask formed from the same. The mask produces a phase difference and thus functions as a phase shifting mask (Kominato, paragraph 0088-0092). The mask includes a light-shielding film (Kominato, paragraph 0088), which is analogous to the light-shielding film of the mask taught by Ohkubo, which is analogous to the claimed intermediate layer, as explained above. The light-shielding film may be formed of a transition metal, such as molybdenum (Mo), tantalum (Ta), chromium (Cr), tungsten (W), titanium (Ti), zirconium (Zr), hafnium (Hf), vanadium (V), niobium (Nb), nickel (Ni), palladium (Pd), iron (Fe), ruthenium (Ru), rhodium (Rh), iridium (Ir), platinum (Pt), zinc (Zn), gold (Au), and silver (Ag) (Kominato, paragraph 0125).
Ohkubo, Maeda, and Kominato are analogous art because each reference pertains to masks and their manufacture. It would have been obvious to one having ordinary skill in the art before the filing date of the instant application to extend a pattern formed in the resist layer all the way to the underlying phase shift layer, as taught by Maeda, using the mask blank taught by Ohkubo because such a patterning technique is commonly utilized in the art to pattern a phase shift layer (Maeda, paragraph 0004). Furthermore, the mask blank taught by Ohkubo can produce a phase shift mask that can reduce temperature rise caused by heat of the phase shift film that generated during exposure (Ohkubo, paragraph 0090). Thus, it would have been obvious to one having ordinary skill in the art before the filing date of the instant application to apply the known patterning technique taught by Maeda to the improved mask blank taught by Ohkubo to achieve a patterned phase shift film possessing the benefits of Ohkubo’s mask blank. It would have been obvious to one having ordinary skill in the art before the filing date of the instant application to include iridium (Ir) in the intermediate layer, as taught by Kominato, in the method obtained from combining the teachings of Ohkubo and Maeda because iridium is taught to be functionally equivalent to chromium for the purposes of a light-shielding layer (Kominato, paragraph 0125), which is the material used by Ohkubo for the light-shielding layer (which is analogous to the claimed intermediate layer).
Regarding Claim 3, Ohkubo discloses that the light-shielding film (4) contains silicon or tantalum and can include a transition metal and/or metal elements other than a transition metal, such as molybdenum (Mo), tantalum (Ta), nickel (Ni), ruthenium (Ru), and palladium (Pd) (Ohkubo, paragraph 0095). A metal alloy of one or more of the above elements may also be used (Ohkubo, paragraph 0095). In some preferred embodiments, the light-shielding film contains at least one or more elements selected from silicon and tantalum (Ohkubo, paragraph 0149).
However, Ohkubo fails to disclose a light-shielding film including iridium (Ir) and one of the metals recited by instant claim 3. Kominato teaches that the light-shielding film may be formed of a transition metal, such as molybdenum (Mo), tantalum (Ta), chromium (Cr), tungsten (W), titanium (Ti), zirconium (Zr), hafnium (Hf), vanadium (V), niobium (Nb), nickel (Ni), palladium (Pd), iron (Fe), ruthenium (Ru), rhodium (Rh), iridium (Ir), platinum (Pt), zinc (Zn), gold (Au), and silver (Ag) (Kominato, paragraph 0125). Furthermore, the light-shielding layer may be formed of an alloy including two or more of the aforementioned elements. Kominato provides a finite number of predictable potential options for forming a light-shielding layer, and teaches that these materials are functionally equivalent to those utilized by Ohkubo. Thus, it would have been obvious to one having ordinary skill in the art before the filing date of the instant application to use a light-shielding film including iridium (Ir) and one or more elements selected from the group of tantalum (Ta), palladium (Pd), nickel (Ni), ruthenium (Ru), and/or gold (Au), as taught by Kominato in place of the chromium-based light-shielding film disclosed by Ohkubo.
Regarding Claim 4, Ohkubo discloses an embodiment wherein the light-shielding film, which is analogous to the claimed intermediate film, is formed of silicon nitride (SiN) (Ohkubo, paragraph 0174).
Regarding Claim 6, Ohkubo discloses an embodiment wherein the hard mask layer(s) is formed of chromium nitride (CrN) (Ohkubo, paragraph 0173).
Regarding Claim 7, Ohkubo discloses that the etching stopper film (2) is formed of a material containing hafnium (Hf), aluminum (Al), and oxygen (O) (Ohkubo, paragraph 0057).
Regarding Claim 8, Ohkubo discloses that in some embodiments, the transmittance of the etching stopper film at a wavelength of 193 nm (provided by an ArF excimer laser) was 96.4% (Ohkubo, paragraph 0194), which is in the range of 95% or more.
Regarding Claim 9, Ohkubo discloses in an exemplary embodiment of the invention that the light-shielding film has a thickness of 48 nm (Ohkubo, paragraph 0174).
Regarding Claim 10, Ohkubo discloses that the phase shift film can be formed of a material containing a transition metal, silicon, and nitrogen; wherein the transition metal may be molybdenum (Mo) (Ohkubo, paragraph 0086).
Regarding Claim 21, Ohkubo teaches that the phase shift material layer is formed of a material containing a transition metal, silicon, and nitrogen (Ohkubo, paragraph 0086). The transition metal may include molybdenum (Mo) (Ohkubo, paragraph 0086). Thus, the phase shift material layer of Ohkubo’s phase shift mask may include Mo and Si.
Claim(s) 5 is rejected under 35 U.S.C. 103 as being unpatentable over US 20220043335 A1 (hereby referred to as Ohkubo) in view of US 20220252972 A1 (hereby referred to as Maeda) and US 20120082924 A1 (hereby referred to as Kominato) as applied to claim 1 above, and further in view of KR 20090004628 A (hereby referred to as KR ‘628).
Regarding Claim 5, the combination of Ohkubo, Maeda, and Kominato renders obvious the method of manufacturing a phase shift mask according to instant claim 1. However, Ohkubo, Maeda, and Kominato are silent in regards to the light-shielding layer (which is analogous to the claimed intermediate layer) comprising an organic polymer containing Si or metal particles.
KR ‘628 teaches a photomask and method of manufacturing the same. The photomask taught by KR ‘628 comprises a light-blocking member (KR ‘628, page 5 lines 5-6 of the English translation). KR ‘628 further teaches that the light-blocking member (which is considered analogous to the light-shielding layer of Ohkubo and the intermediate layer of the instant application) comprises a metal particle-containing film (KR ‘628, page 3 lines 4-8 of the English translation). Specifically, the metal particle-containing film is formed by polymerizing a radically-polymerizable compound and providing metal ions or metal salts to the polymer layer (KR ‘628, page 5 lines 15- 21). Thus, the light-shielding film obtained is a polymeric material containing metal particles.
Ohkubo, Maeda, Kominato, and KR ‘628 are analogous art because each reference pertains to masks and their manufacture. It would have been obvious to one having ordinary skill in the art before the filing date of the instant application to use an organic polymer containing metal particles, as taught by KR ‘628, as the light-shielding layer in the mask blank used in the method of manufacturing the photomask obtained by combining the teachings of Ohkubo, Maeda, and Kominato because a light-shielding film including an organic polymer containing metal particles exhibits excellent adhesion and light-shielding properties (KR ‘628, page 40 lines 3-7 of the English translation), thus making it desirable for use as a light-shielding layer.
Claim(s) 11-14, 16-17, and 19 are rejected under 35 U.S.C. 103 as being unpatentable over US 20220043335 A1 (hereby referred to as Ohkubo) in view of US 20220252972 A1 (hereby referred to as Maeda), US 20110159411 A1 (hereby referred to as Olson), and US 20120082924 A1 (hereby referred to as Kominato).
Regarding Claims 11 and 19, Ohkubo discloses a mask blank, a transfer mask, and a semiconductor device manufacturing method. The transfer mask is manufactured by patterning a mask blank (Ohkubo, paragraph 0150). The mask blank (120) comprises a transparent substrate (1), an etching stopper film (2), a phase shift film (3), a hard mask film (11), and a light-shielding film (4) (Ohkubo, paragraph 0217-0231; paragraph 0144, and Fig. 7). A second hard mask (12) is disposed over the light-shielding film (see paragraph 0144 and Fig. 7 of Ohkubo). The light-shielding film (4) is considered analogous to the claimed “intermediate” film. The above-described mask blank thus comprises a multilayer structure including N-pairs of a hard mask layer and an intermediate layer on the hard mask layer, wherein N is 1 (and thus a natural number up to five). To produce the transfer mask, a resist film is formed over the mask blank, and a pattern to be formed in the light-shielding film (4) is written on the resist film with an electron beam, thus forming a resist pattern (Ohkubo, paragraph 0152 and Fig. 9A). Dry etching is carried out using a mixed gas with the resist pattern acting as an etching mask, thus forming a pattern in the second hard mask (12) (Ohkubo, paragraph 0152). The patterned second hark mask is used as an etching mask to pattern the light-shielding film (4) (Ohkubo, paragraph 0153). Additional etching is performed for the first hard mask layer (11) and the phase shift layer (3), using the patterned layer disposed over each of these layers as an etching mask (Ohkubo, paragraph 0154-0156 and Fig. 9A-9G). It is preferred that the light-shielding film (4), which is analogous to the intermediate layer of the instant application, is formed of a material containing silicon or tantalum (Ohkubo, paragraph 0144). The hard mask preferably contains chromium (Ohkubo, paragraph 0144), and therefore the light-shielding film and the hard mask are made of different materials.
However, Ohkubo fails to teach the extension of the pattern formed in the resist layer into the hard mask layer and the phase shift layer. Maeda teaches a mask blank and a phase shift mask. The mask blank comprises a substrate having a phase shift film, a light shielding film, and a hard mask formed upon it (Maeda, paragraph 0066 and Fig. 1). To convert the mask blank into a phase shift mask, a resist film is formed over the mask blank and patterned (Maeda, paragraph 0069). The pattern formed on the resist film is intended to be transfer to the phase shift film (Maeda, paragraph 0069). The pattern is transferred from the resist film to the phase shift film by etching each of the underlying layers using a dry etching technique (Maeda, paragraph 0069-0070 and Fig. 2A-2D). An additional pattern may be formed afterwards (Maeda, paragraph 0071).
However, Ohkubo and Maeda are silent in regards to multiple sets of hard masks and light-shielding layers. Olson teaches phase shift photomasks and patterning methods. The phase shift photomask blank includes multiple hard mask regions (Olson, paragraph 0023). The hard mask regions are separated by intermediate layers (Olson, paragraph 0023 and Fig. 2-3). Olson teaches that the inclusion of multiple hard mask regions allows for separate patterning of the underlying regions (Olson, paragraph 0023). Further, Olson teaches that patterning using multiple hard mask regions allows for patterns with smaller feature sizes to be produced, compared to if a singular hard mask structure was utilized (Olson, paragraph 0009 and 0023).
However, Ohkubo, Maeda, and Olson are silent in regards to an intermediate layer including iridium (Ir). Kominato teaches a mask blank and a mask formed from the same. The mask produces a phase difference and thus functions as a phase shifting mask (Kominato, paragraph 0088-0092). The mask includes a light-shielding film (Kominato, paragraph 0088), which is analogous to the light-shielding film of the mask taught by Ohkubo, which is analogous to the claimed intermediate layer, as explained above. The light-shielding film may be formed of a transition metal, such as molybdenum (Mo), tantalum (Ta), chromium (Cr), tungsten (W), titanium (Ti), zirconium (Zr), hafnium (Hf), vanadium (V), niobium (Nb), nickel (Ni), palladium (Pd), iron (Fe), ruthenium (Ru), rhodium (Rh), iridium (Ir), platinum (Pt), zinc (Zn), gold (Au), and silver (Ag) (Kominato, paragraph 0125).
Ohkubo, Maeda, Olson, and Kominato are analogous art because each reference pertains to photomask manufacturing. It would have been obvious to one having ordinary skill in the art before the filing date of the instant application to extend a pattern formed in the resist layer all the way to the underlying phase shift layer, as taught by Maeda, using the mask blank taught by Ohkubo because such a patterning technique is commonly utilized in the art to pattern a phase shift layer (Maeda, paragraph 0004). Furthermore, the mask blank taught by Ohkubo can produce a phase shift mask that can reduce temperature rise caused by heat of the phase shift film that generated during exposure (Ohkubo, paragraph 0090). Thus, it would have been obvious to one having ordinary skill in the art before the filing date of the instant application to apply the known patterning technique taught by Maeda to the improved mask blank taught by Ohkubo to achieve a patterned phase shift film possessing the benefits of Ohkubo’s mask blank. Additionally, it would have been obvious to one having ordinary skill in the art before the filing date of the instant application to use multiple hard mask structures, as taught by Olson, using the hard mask structure comprising a hard mask with a light-shielding layer disposed above the hard mask, as taught by Ohkubo, because the inclusion of multiple hard mask structures allows for separate patterning to be performed (Olson, paragraph 0023) and yields smaller feature sizes (and thus finer resolution) than using a singular hard mask structure (Olson, paragraph 0009 and 0023). It would have been obvious to one having ordinary skill in the art before the filing date of the instant application to include iridium (Ir) in the intermediate layer, as taught by Kominato, in the method obtained from combining the teachings of Ohkubo, Maeda, and Olson because iridium is taught to be functionally equivalent to chromium for the purposes of a light-shielding layer (Kominato, paragraph 0125), which is the material used by Ohkubo for the light-shielding layer (which is analogous to the claimed intermediate layer). The proposed combination would yield the invention according to instant claim 11 and an embodiment of instant claim 18 wherein N is 3 or more.
Regarding Claim 12, Ohkubo discloses an embodiment wherein the hard mask layer(s) is formed of chromium nitride (CrN) (Ohkubo, paragraph 0173).
Regarding Claim 13, Ohkubo discloses that the light-shielding film (4) contains silicon and can include a transition metal and/or metal elements other than a transition metal, such as molybdenum (Mo), tantalum (Ta), nickel (Ni), ruthenium (Ru), and palladium (Pd) (Ohkubo, paragraph 0095). A metal alloy of one or more of the above elements may also be used (Ohkubo, paragraph 0095). In some preferred embodiments, the light-shielding film contains at least one or more elements selected from silicon and tantalum (Ohkubo, paragraph 0149).
However, Ohkubo fails to disclose a light-shielding film including iridium (Ir) and one of the metals recited by instant claim 3. Kominato teaches that the light-shielding film may be formed of a transition metal, such as molybdenum (Mo), tantalum (Ta), chromium (Cr), tungsten (W), titanium (Ti), zirconium (Zr), hafnium (Hf), vanadium (V), niobium (Nb), nickel (Ni), palladium (Pd), iron (Fe), ruthenium (Ru), rhodium (Rh), iridium (Ir), platinum (Pt), zinc (Zn), gold (Au), and silver (Ag) (Kominato, paragraph 0125). Furthermore, the light-shielding layer may be formed of an alloy including two or more of the aforementioned elements. Kominato provides a finite number of predictable potential options for forming a light-shielding layer, and teaches that these materials are functionally equivalent to those utilized by Ohkubo. Thus, it would have been obvious to one having ordinary skill in the art before the filing date of the instant application to use a light-shielding film including iridium (Ir) and one or more elements selected from the group of tantalum (Ta), palladium (Pd), nickel (Ni), ruthenium (Ru), and/or gold (Au), as taught by Kominato in place of the chromium-based light-shielding film disclosed by Ohkubo.
Regarding Claim 14, Ohkubo discloses an embodiment wherein the light-shielding film, which is analogous to the claimed intermediate film, is formed of silicon nitride (SiN) (Ohkubo, paragraph 0174).
Regarding Claim 16, Ohkubo discloses that the etching stopper film (2) is formed of a material containing hafnium (Hf), aluminum (Al), and oxygen (O) (Ohkubo, paragraph 0057).
Regarding Claim 17, Ohkubo discloses that the phase shift film can be formed of a material containing a transition metal, silicon, and nitrogen; wherein the transition metal may be molybdenum (Mo) (Ohkubo, paragraph 0086).
Claim(s) 15 is rejected under 35 U.S.C. 103 as being unpatentable over US 20220043335 A1 (hereby referred to as Ohkubo) in view of US 20220252972 A1 (hereby referred to as Maeda), US 20110159411 A1 (hereby referred to as Olson), and US 20120082924 A1 (hereby referred to as Kominato) as applied to claim 12 above, and further in view of KR 20090004628 A (hereby referred to as KR ‘628).
Regarding Claim 15, the combination of Ohkubo, Maeda, Olson, and Kominato renders obvious the method of manufacturing a phase shift mask according to instant claim 11. Ohkubo further discloses that the hard mask layers are made of chromium nitride (CrN) (Ohkubo, paragraph 0173).
However, Ohkubo, Maeda, Olson, and Kominato are silent in regards to the light-shielding layer (which is analogous to the claimed intermediate layer) comprising an organic polymer containing Si or metal particles. KR ‘628 teaches a photomask and method of manufacturing the same. The photomask taught by KR ‘628 comprises a light-blocking member (KR ‘628, page 5 lines 5-6 of the English translation). KR ‘628 further teaches that the light-blocking member (which is considered analogous to the light-shielding layer of Ohkubo and the intermediate layer of the instant application) comprises a metal particle-containing film (KR ‘628, page 3 lines 4-8 of the English translation). Specifically, the metal particle-containing film is formed by polymerizing a radically-polymerizable compound and providing metal ions or metal salts to the polymer layer (KR ‘628, page 5 lines 15- 21). Thus, the light-shielding film obtained is a polymeric material containing metal particles.
Ohkubo, Maeda, Olson, Kominato, and KR ‘628 are analogous art because each reference pertains to photomasks and their manufacture. It would have been obvious to one having ordinary skill in the art before the filing date of the instant application to use an organic polymer containing metal particles, as taught by KR ‘628, as the light-shielding layer in the mask blank used in the method of manufacturing the photomask obtained by combining Ohkubo, Maeda, Olson, and Kominato because a light-shielding film including an organic polymer containing metal particles exhibits excellent adhesion and light-shielding properties (KR ‘628, page 40 lines 3-7 of the English translation), thus making it desirable for use as a light-shielding layer.
Claim(s) 20 is rejected under 35 U.S.C. 103 as being unpatentable over US 20220043335 A1 (hereby referred to as Ohkubo) in view of US 20220252972 A1 (hereby referred to as Maeda) and US 20120082924 A1 (hereby referred to as Kominato) as applied to claim 18 above, and further in view of US 20020068229 A1 (hereby referred to as Westerman).
Regarding Claim 20, the combination of Ohkubo, Maeda, and Kominato renders obvious a method of manufacturing a phase shift photomask according to instant claim 18. The phase shift photomask includes an etching stopper layer disposed on the transparent substrate (Ohkubo, paragraph 0217-0231; paragraph 0144, and Fig. 7). However, Ohkubo, Maeda, and Kominato are silent in regards to the etching stopper layer being patterned.
Westerman teaches attenuated phase shift masks and their manufacture. The phase shift mask taught by Westerman comprises a transparent substrate containing an etch stop layer disposed over the substrate (Westerman, paragraph 0028-0029). A phase shift layer is disposed over the etch stop layer (Westerman, paragraph 0029 and Fig. 2). It is apparent that this layout is analogous to that of Ohkubo and the instant application. Westerman further teaches that the etch stop layer can comprise substantially transparent materials such as Al2O3 (Westerman, paragraph 0038). In an optional step, the etch stop layer is etched in a patternwise manner (Westerman, paragraph 0050 and Fig. 5C). In some embodiments, such as when the transmission of the etch stop layer is acceptable, the patterning of the etch stop layer is omitted (Westerman, paragraph 0051).
Ohkubo, Maeda, Kominato, and Westerman are analogous art because each reference pertains to masks and their manufacture. It would have been obvious to one having ordinary skill in the art before the filing date of the instant application to pattern the etching stopper layer, as taught by Westerman, in the method of manufacturing a phase shift mask obtained by combining the teachings of Ohkubo, Maeda, and Kominato because the patterning of the etching stopper layer improves the light transmission of the phase shift mask when the etching stopper film is not produced of a highly optically transparent material having low thickness (Westerman, paragraph 0051-0052).
Conclusion
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/JAYSON D COSGROVE/Examiner, Art Unit 1737
/NICHOLAS A WANG/Primary Examiner, Art Unit 1734
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