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
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) 1-8, 10, 13, and 19-20 are rejected under 35 U.S.C. 103 as being unpatentable over US 20190146325 A1 (hereby referred to as Hsueh).
Regarding Claims 1, 10, and 19, Hsueh discloses an extreme ultraviolet (EUV) mask and a method of manufacturing the same. Hsueh shows an EUV mask blank in Fig. 4A (Hsueh, paragraph 0077). The EUV mask blank comprises a substrate (200), a first reflective multilayer formed on the substrate (206), a capping layer (210), a first absorption layer (212A), a second reflective multilayer (236), an etch stop layer (214), a third reflective multilayer (246), a second absorption layer (212B), a third absorption layer (216), and a hard mask layer (220) (Hsueh, paragraph 0075-0078). The lexicography utilized by Hsueh’s disclosure is different from the Applicant’s disclosure. The instant application states (in paragraphs 0023 and 0025 of the specification) that the first and second adjust layers may be a multilayer of Mo/Si film pairs. Hsueh’s second and third reflective multilayers similarly are a multilayer of Mo/Si film pairs (Hsueh, paragraphs 0048 and 0062). Thus, the second and third reflective multilayers of Hsueh are analogous to the first and second adjust layers of the instant application. Hsueh also discloses that the etch stop layer 214 includes tantalum, aluminum, ruthenium, nickel, chromium, their respective oxides, nitrides, or borides, or a combination thereof (Hsueh, paragraph 0025). The etch stop layer may be tantalum boron oxide (TaBO) (Hsueh, paragraph 0025). The instant application states that the second absorption layer includes TaBO (see paragraph 0024 of the instant application’s specification) and that the second absorption layer functions as an etch stop layer (see paragraph 0033 of the instant application’s specification). Thus, the etch stop layer of Hsueh is analogous to the second absorption layer of the instant application’s invention. A summary table of the terminology of the instant application and the analogue of Hsueh’s disclosure is provided below.
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As can be seen in the above table, in addition to the evidence cited from the instant application’s specification and Hsueh’s disclosure, the structure of the mask blank of the instant application and the mask blank of Hsueh is substantially the same. Hsueh further teaches that following the formation of the mask blank, the processes shown in Figs. 1B-1C are performed to form hard mask patterns (220A) over the uppermost absorption layer (216) (Hsueh, paragraph 0079). The patterning processes of Figs. 1B-1C include the formation of a photoresist layer (222) over the hard mask layer (Hsueh, paragraph 0033), patterning the photoresist layer to form photoresist patterns (222A) (Hsueh, paragraph 0034), and etching the hard mask layer to form hard mask patterns (220A) using the photoresist patterns as an etching mask (Hsueh, paragraph 0035 and 0079). Then, a first patterning process (460) is performed to form openings passing through the absorption layer (216), the absorption layer (212B), and the third reflective multilayer (246) until the etch stop layer (214) is exposed (Hsueh, paragraph 0079). Refer to Fig. 4B of Hsueh. This is analogous to the first absorber patterning process recited by instant claim 1. A second patterning process (462) is then performed to form openings passing through the etch stop layer (214), the second reflective multilayer (236), and the absorption layer (212A) until the capping layer (210) is exposed (Hsueh, paragraph 0080). Refer to Fig. 4C of Hsueh. This is analogous to the second absorber patterning process recited by instant claim 1. Following the second patterning process, the patterned hard mask layer is removed (Hsueh, paragraph 0081 and Fig. 4D).
However, Hsueh fails to disclose that the two uppermost absorption layers (analogous to the fourth and third absorption layers of instant claim 1) are removed following the second absorber patterning process. The Examiner notes that the patterned hard mask is removed via an etching process (Hsueh, paragraph 0081). Furthermore, Hsueh teaches that the hard mask layer may be formed of various materials, including silicon-based compounds, metal oxides, metal nitrides, or other suitable materials (Hsueh, paragraph 0032). Specific examples provided include TaBN, chromium oxynitride, and aluminum oxynitride (Hsueh, paragraph 0032). Hsueh further teaches that the absorption layer(s) may be formed of similar materials, such as TaBN, metal oxides and/or nitrides, and the like (Hsueh, paragraph 0023 and 0025). Thus, the broader disclosure of Hsueh suggests embodiments wherein the hard mask layer is formed of a compositionally similar or identical material as the absorption layers. See, for instance, paragraph 0038 of Hsueh. Therefore, it would have been “obvious to try” (refer to MPEP 2143 I. E.) a mask blank structure as described above, wherein the hard mask layer and the two uppermost absorption layers are formed of similar or identical materials. In such an embodiment, the etching process that removes the patterned hard mask would be expected to also remove the uppermost patterned absorption layers, due to the layers having similar or identical etching characteristics. Furthermore, upon the removal of said uppermost patterned absorption layers, the mask according to instant claim 19 is obtained.
Regarding Claims 2-3, Hsueh discloses that the second and third reflective multilayers (236 and 246, respectively), which are analogous to the first and second adjust layers of the instant application, respectively, comprise a plurality of Mo/Si film pairs (Hsueh, paragraphs 0048 and 0062). The number of pairs in the second and third reflective multilayers is between two to ten (2 to 10) (Hsueh, paragraphs 0048 and 0062). The range of the number of pairs overlaps with the claimed range of film pairs and thus, per MPEP 2144.05 I., a prima facie case of obviousness exists.
Regarding Claim 4, Hsueh teaches that the thickness of each of the film pairs in the second reflective multilayer (236) (analogous to the first adjust layer of the instant application) have a thickness ratio with respect to the thickness of the film pairs in the first reflective multilayer (206) (analogous to the reflective multilayer of the instant application) equal to N/2, wherein N is a positive integer (Hsueh, paragraph 0049). The same case is true for the third reflective multilayer (246) (analogous to the second adjust layer of the instant application) with respect to the first reflective multilayer (206) (Hsueh, paragraph 0063). Hsueh further teaches that the thickness of the first layer of the third reflective multilayer with respect to the thickness of the first layer of the second reflective multilayer is a ratio of N/2 (Hsueh, paragraph 0063). Hsueh suggests an embodiment wherein the first layer of the second reflective multilayer has a thickness of 4 nm, whilst the first layer of the third reflective multilayer has a thickness of 2 nm, 4 nm, 6 nm, etc. (Hsueh, paragraph 0063). Thus, Hsueh suggests an embodiment wherein at least one of the conditions recited by instant claim 4 is satisfied.
Regarding Claim 5, Hsueh teaches materials for each of the layers 212A, 214, 212B, and 216, which are analogous to the first through fourth absorption layers of the instant application, respectively (see Hseuh, paragraph 0023, and 0025-0029). In some embodiments, the materials used for each of the respective layers differ (see Hseuh, paragraph 0025-0029).
Regarding Claim 6, Hsueh teaches that the first absorption layer (212A) is formed of Ta-based materials, including tantalum nitride (TaN) (Hsueh, paragraph 0023).
Regarding Claim 7, Hsueh teaches that the etch stop layer (214), which is analogous to the second absorption layer of the instant application, may include ruthenium (Ru) (Hsueh, paragraph 0025).
Regarding Claim 8, Hsueh teaches that the second absorption layer (212B), which is analogous to the third absorption layer of the instant application, may be formed of similar materials as those that may be used for the first absorption layer (212A) (Hsueh, paragraph 0027). Hsueh further teaches that suitable materials include tantalum oxide (TaO) and tantalum boron oxide (TaBO) (Hsueh, paragraph 0023).
Regarding Claim 13, Hsueh teaches that after performing the patterning processes, the mask comprises opaque regions (314C) and reflective regions (316C) (Hsueh, paragraph 0072 and Fig. 4D). As can be seen in Fig. 4D of Hsueh, the reflective regions lack absorption layers disposed over the reflective multilayer, whilst the opaque regions have absorption layers disposed over the reflective multilayer. As noted in regards to claim 1 (see above), when the materials of the absorption layers are chosen such that they are removed during the etching of the hard mask layer, the uppermost layer of the patterned mask remaining would be the third reflective multilayer (246A), which is analogous to the patterned second adjust layer. However, such a configuration would provide solely reflective regions (316C), due to the lack of absorption layers. Therefore, it would be obvious to remove the uppermost patterned reflective multilayer as well, thus preserving the opaque and reflective regions as shown in Fig. 4D of Hsueh. One having ordinary skill in the art would be motivated to preserve the opaque and reflective regions because structuring the mask into such regions enhances resolution and image quality of the mask (see Hsueh, paragraph 0050).
Regarding Claim 20, Hsueh discloses that the second and third reflective multilayers, which are analogous to the first and second reflective multilayers as recited by claim 19, respectively, may comprise a plurality of Mo/Si film pairs (Hsueh, paragraph 0048 and 0062)
Claim(s) 9 is rejected under 35 U.S.C. 103 as being unpatentable over US 20190146325 A1 (hereby referred to as Hsueh) in view of US 20110117479 A1 (hereby referred to as Suga).
Regarding Claim 9, Hsueh renders obvious the method of manufacturing a reflective mask according to instant claim 1. Hsueh teaches that the absorption layer (216), which is analogous to the fourth absorption layer of the instant application, may be formed of similar materials as the etch stop layer (214) (Hsueh, paragraph 0029). Suitable materials include tantalum, aluminum, ruthenium, nickel, chromium, and oxides, nitrides, or borides thereof (Hsueh, paragraph 0025).
However, Hsueh is silent in regards to an absorber comprising a silicide. Suga teaches a reflective exposure mask and a method of manufacturing the same. Suga’s mask comprises a substrate, a multilayer reflecting film, and an absorber layer (Suga, paragraph 0089-0093). The material of the absorber layer is a metal-based compound, such as tantalum boride nitride (TaBN), tantalum silicide (TaSi), tantalum nitride (TaN), tantalum carbide nitride (TaCN), tantalum carbide (TaC), chromium nitride (CrN) and the like (Suga, paragraph 0093). Suga teaches that materials such as tantalum nitride and chromium nitride, which are suitable materials for the absorption layer in Hsueh’s reflective mask (see Hsueh, paragraph 0025 and 0029), are functionally equivalent to tantalum silicide for the purposes of an absorber layer in a reflective EUV mask.
Hsueh and Suga are analogous art because each reference pertains to EUV 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 tantalum silicide as the material of the uppermost absorption layer, as taught by Suga, in the method of manufacturing a reflective mask rendered obvious by Hsueh because Suga teaches that tantalum silicide is a functional equivalent to materials utilized by Hsueh as an absorption layer. Per MPEP 2144.06 II., substitution of equivalents known for the same purpose presents a prima facie case of obviousness.
Claim(s) 11 is rejected under 35 U.S.C. 103 as being unpatentable over US 20190146325 A1 (hereby referred to as Hsueh) in view of US 20210033960 A1 (hereby referred to as Hsu) and US 20210132487 A1 (hereby referred to as Shin).
Regarding Claim 11, Hsueh renders obvious the method of claim 10, as discussed above. However, Hsueh is silent in regards to the formation of a Si-containing layer on the side faces of the patterned absorption layer.
Hsu teaches a surface treatment method for EUV masks. The Examiner notes that the formation of the Si-containing layer of the instant application is taught to be a surface treatment (see paragraph 0036 of the instant application). Hsu teaches an absorber layer that is patterned to form a trench (Hsu, paragraph 0082). This is analogous to the patterning taught by Hsueh. Hsu further teaches that the width of the trenches is controlled by performing a surface treatment on the sidewalls of the patterned absorber layer utilizing plasma (Hsu, paragraph 0082 and 0086).
However, Hsu fails to teach a Si-based material applied during the surface treatment. Shin teaches a photomask for EUV lithography. Shin teaches the use of silicon-based materials as a protective film (Shin, paragraph 0054). The Examiner notes that the surface treatment of the instant application is performed to protect the sidewalls of the absorption layer (see paragraph 0036 of the instant application). Shin teaches that the formation of silicon layers mitigates oxidation effects (Shin, paragraph 0054). Additional treatment may be performed to prevent changes in the film (Shin, paragraph 0054).
Hsueh, Hsu, and Shin are analogous art because each reference pertains to EUV 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 perform a surface treatment on the side walls of the absorption layer, as taught by Hsu, in the method rendered obvious by Hsueh because the surface treatment allows for the width of the openings formed in the pattern of the absorber layer to be adjusted to a desired value, thereby improving critical dimension accuracy (see Hsu, paragraph 0082 and 0086). It would have been obvious to one having ordinary skill in the art before the filing date of the instant application to use a Si-based material as the surface treating material, as taught by Shin because Si-based materials, especially when further treated, mitigate oxidation and thus preserve the thickness of the treatment layer (Shin, paragraph 0054), which further aids in improving critical dimension accuracy.
Claim(s) 12 and 14-17 are rejected under 35 U.S.C. 103 as being unpatentable over US 20190146325 A1 (hereby referred to as Hsueh) in view of US 20140038086 A1 (hereby referred to as Shih).
Regarding Claim 12, Hsueh renders obvious a method according to instant claim 1, as discussed above. However, Hsueh is silent in regards to a black border region.
Shih teaches a mask for EUV lithography and a method of fabricating the same. The mask includes a substrate having a reflective multilayer formed upon the substrate (Shih, paragraph 0015). A capping layer is disposed over the reflective multilayer (Shih, paragraph 0016). The mask also includes an absorption stack comprising two absorber layers (Shih, paragraph 0019). Shih teaches that the mask includes a mask image region which is absent of at least one of the absorber layers and a mask black border region that includes both absorber layers and the reflective multilayer (Shih, paragraph 0020 and Fig. 2). Notably, in Fig. 2 of Shih, the lower absorber layer is at least partially present in the mask image region, whereas the upper absorber layer is absent from the mask image region. This is analogous to forming absorber patterns composed of a first absorption layer by removing layers disposed upon the first absorption layer in a specified region.
Hsueh and Shih are analogous art because both references pertain to EUV 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 include a black border region in the mask, as taught by Shih, that includes the absorption layers of the mask taught by Hsueh because the inclusion of a black border region including the absorption layers reduces reflectivity of the mask black border region, thereby enhancing aerial image contrast realized by the mask during device fabrication (Shih, paragraph 0020).
Regarding Claim 14, Hsueh teaches an extreme ultraviolet (EUV) mask and a method of manufacturing the same. Hsueh shows an EUV mask blank in Fig. 3A (Hsueh, paragraph 0061). The EUV mask blank comprises a substrate (200), a first reflective multilayer formed on the substrate (206), a capping layer (210), a first absorption layer (212A), an etch stop layer (214), a third reflective multilayer (246), a second absorption layer (212B), a third absorption layer (216), and a hard mask layer (220) (Hsueh, paragraph 0061-0065). Hsueh teaches that the first absorption layer (212A) and the etch stop layer (214) form a first absorption film pair and the second absorption layer (212B) and the third absorption layer (216) form a second absorption film pair (Hsueh, paragraph 0073). The lexicography utilized by Hsueh’s disclosure is different from the Applicant’s disclosure. Refer to the table above in regards to instant claim 1. In this embodiment of Hsueh’s invention, the first absorption film pair (212A + 214) is analogous to the first absorption layer of the instant invention; the third reflective multilayer (246) is analogous to the adjust layer of the instant invention; and the second absorption film pair (212B + 216) is analogous to the second absorption layer. Following the assembling of the mask blank, the processes shown in Figs. 1B-1C are performed to form hard mask patterns (Hsueh, paragraph 0068). The patterning processes of Figs. 1B-1C include the formation of a photoresist layer (222) over the hard mask layer (Hsueh, paragraph 0033), patterning the photoresist layer to form photoresist patterns (222A) (Hsueh, paragraph 0034), and etching the hard mask layer to form hard mask patterns (220A) using the photoresist patterns as an etching mask (Hsueh, paragraph 0035 and 0068). Then, a first patterning process (460) is performed to form openings passing through the absorption layer (216), the absorption layer (212B), and the third reflective multilayer (246) until the etch stop layer (214) is exposed (Hsueh, paragraph 0068). Refer to Fig. 3B of Hsueh. A second patterning process (362) is then performed to form openings passing through the etch stop layer (214) and the absorption layer (212A) until the capping layer (210) is exposed (Hsueh, paragraph 0070). Refer to Fig. 3C of Hsueh.
However, Hsueh is silent in regards to a black border region. Shih teaches a mask for EUV lithography and a method of fabricating the same. The mask includes a substrate having a reflective multilayer formed upon the substrate (Shih, paragraph 0015). A capping layer is disposed over the reflective multilayer (Shih, paragraph 0016). The mask also includes an absorption stack comprising two absorber layers (Shih, paragraph 0019). Shih teaches that the mask includes a mask image region which is absent of at least one of the absorber layers and a mask black border region that includes both absorber layers and the reflective multilayer (Shih, paragraph 0020 and Fig. 2).
Hsueh and Shih are analogous art because both references pertain to EUV 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 include a black border region in the mask, as taught by Shih, that includes the absorption layers of the mask taught by Hsueh because the inclusion of a black border region including the absorption layers reduces reflectivity of the mask black border region, thereby enhancing aerial image contrast realized by the mask during device fabrication (Shih, paragraph 0020).
Regarding Claim 15, Hsueh teaches that the third reflective multilayer (246), which is analogous to the adjust layer of the instant invention, comprises a plurality of Mo/Si film pairs (Hsueh, paragraph 0062). The number of film pairs ranges from two to ten (2 to 10) pairs (Hsueh, paragraph 0062). The range of the number of pairs overlaps with the claimed range of film pairs and thus, per MPEP 2144.05 I., a prima facie case of obviousness exists.
Regarding Claim 16, Hsueh teaches that the first and second layers of the third reflective multilayer (246), which is analogous to the adjust layer, satisfy a thickness ratio with respect to the first and second layers of the first reflective multilayer (206) (Hsueh, paragraph 0063). In particular, Hsueh teaches that the thickness of the first layer may be 2 nm, 4 nm, or 6 nm and the thickness of the second layer may be 1.5 nm, 3 nm, or 4.5 nm (Hsueh, paragraph 0063).
Regarding Claim 17, Hsueh teaches that the absorption layers may be formed of different materials (Hsueh, paragraph 0061 and 0065; see also paragraph 0023, 0025, and 0030).
Claim(s) 18 is rejected under 35 U.S.C. 103 as being unpatentable over US 20190146325 A1 (hereby referred to as Hsueh) in view of US 20140038086 A1 (hereby referred to as Shih), as applied to claim 15 above, and further in view of US 20110117479 A1 (hereby referred to as Suga) and US 20140254018 A1 (hereby referred to as Sun).
Regarding Claim 18, the combination of Hsueh and Shih renders obvious the method of manufacturing a reflective mask according to instant claim 15. Hsueh teaches that the absorption layer (216), which is analogous to the fourth absorption layer of the instant application, may be formed of similar materials as the etch stop layer (214) (Hsueh, paragraph 0029). Suitable materials include tantalum, aluminum, ruthenium, nickel, chromium, and oxides, nitrides, or borides thereof (Hsueh, paragraph 0025).
However, Hsueh and Shih are silent in regards to an absorber comprising a silicide or an absorber comprising platinum (Pt). Suga teaches a reflective exposure mask and a method of manufacturing the same. Suga’s mask comprises a substrate, a multilayer reflecting film, and an absorber layer (Suga, paragraph 0089-0093). The material of the absorber layer is a metal-based compound, such as tantalum boride nitride (TaBN), tantalum silicide (TaSi), tantalum nitride (TaN), tantalum carbide nitride (TaCN), tantalum carbide (TaC), chromium nitride (CrN) and the like (Suga, paragraph 0093). Suga teaches that materials such as tantalum nitride and chromium nitride, which are suitable materials for the absorption layer in Hsueh’s reflective mask (see Hsueh, paragraph 0025 and 0029), are functionally equivalent to tantalum silicide for the purposes of an absorber layer in a reflective EUV mask.
However, Hsueh, Shih, and Suga are silent in regards to platinum-based absorbers. Sun teaches absorbers for EUV reflective masks. Sun teaches an absorber layer for a mask which may be formed of materials such as TaN, TaNO, TaBN, TaBO, Ni, Au, Ag, Te, C, Pt, Pd, or Cr (Sun, paragraph 0037 and 0045). Thus, Sun teaches that tantalum-based absorbers, such as those utilized by Hsueh as the absorption layer(s), are functionally equivalent to Pt-based materials when used as an absorber layer in EUV reflective masks.
Hsueh, Shih, Suga, and Sun are analogous art because each reference pertains to EUV 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 tantalum silicide as the material of the uppermost absorption layer, as taught by Suga, in the method of manufacturing a reflective mask rendered obvious by combining the teachings of Hsueh and Shih because Suga teaches that tantalum silicide is a functional equivalent to materials utilized by Hsueh as an absorption layer. Similarly, it would have been obvious to one having ordinary skill in the art before the filing date of the instant application to use a platinum-based material as the material of the lower absorption layer, as taught by Sun, in the method of manufacturing a reflective mask rendered obvious by combining the teachings of Hsueh and Shih because Sun teaches that Pt-based materials are functionally equivalent to the materials utilized by Hsueh as an absorber layer. Per MPEP 2144.06 II., substitution of equivalents known for the same purpose presents a prima facie case of obviousness
Conclusion
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/JAYSON D COSGROVE/Examiner, Art Unit 1737
/JONATHAN JOHNSON/Supervisory Patent Examiner, Art Unit 1734
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