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 .
The response of the applicant has been read and given careful consideration. Rejection of the previous action not repeated below are withdrawn based upon the amendment and arguments of the applicant. Responses to the arguments of the applicant are presented after the first rejection they are directed to.
The following is a quotation of the first paragraph of 35 U.S.C. 112(a):
(a) IN GENERAL.—The specification shall contain a written description of the invention, and of the manner and process of making and using it, in such full, clear, concise, and exact terms as to enable any person skilled in the art to which it pertains, or with which it is most nearly connected, to make and use the same, and shall set forth the best mode contemplated by the inventor or joint inventor of carrying out the invention.
The following is a quotation of the first paragraph of pre-AIA 35 U.S.C. 112:
The specification shall contain a written description of the invention, and of the manner and process of making and using it, in such full, clear, concise, and exact terms as to enable any person skilled in the art to which it pertains, or with which it is most nearly connected, to make and use the same, and shall set forth the best mode contemplated by the inventor of carrying out his invention.
Claims 1,3-5 and 8-23 are rejected under 35 U.S.C. 112(a) or 35 U.S.C. 112 (pre-AIA ), first paragraph, as failing to comply with the written description requirement. The claim(s) contains subject matter which was not described in the specification in such a way as to reasonably convey to one skilled in the relevant art that the inventor or a joint inventor, or for applications subject to pre-AIA 35 U.S.C. 112, the inventor(s), at the time the application was filed, had possession of the claimed invention.
The specification does not support the full scope of the silicon layers having different thicknesses. The specification describes the thickness of the nitride surfaces/layers of the silicon layers decreasing with increasing depth in the reflective stack with the sum of the thicknesses of the silicon and adjacent nitride surfaces/layers being constant (see prepub of the specification at [0041]). This is due to the extent/likelihood of oxidation being reduced with increasing distance from the top surface of the reflective multilayer.
This disclosure supports the thickness of the silicon layers increasing with increasing distance from the third nitride layer, the oxide or the anti-oxidation layer
On page 1 of the response of the response of 3/16/2026, the applicant asserts that the requirements are met, but does not point out in the specification where support for the full breadth of different thicknesses of the third (Silicon) layer for adjacent multilayer (cycles) is found. The rejection stands.
In claim1 at line 9, “a patterned layer” should read - - a patterned absorber layer- - as this is the only material described as being patterned on the mask. (claims 1,3-5, and 21-23)
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 1,3-5 and 21-23 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.
In claim 1 at line 9, the claims should recite - - a patterned absorber layer- - instead of “a patterned layer” .
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 the appropriate paragraphs of 35 U.S.C. 102 that form the basis for the rejections under this section made in this Office action:
A person shall be entitled to a patent unless –
(a)(1) the claimed invention was patented, described in a printed publication, or in public use, on sale, or otherwise available to the public before the effective filing date of the claimed invention.
(a)(2) the claimed invention was described in a patent issued under section 151, or in an application for patent published or deemed published under section 122(b), in which the patent or application, as the case may be, names another inventor and was effectively filed before the effective filing date of the claimed invention.
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 8-14 are rejected under 35 U.S.C. 103 as obvious over Quesnel 20040233535, in view of Mikami 20150160548 and Mikami et al. 20130115547.
Quesnel 20040233535 teaches EUV reflective multilayers formed by stacking 4.1 Mo/2.8 nm a-Si films [0030]. There may be an intermediate layer between the layers formed of a metal nitride, metal boride or metal carbide,. carbon or boron carbide to improve reflectivity while keeping mechanical stability up to 350 degrees C. [0032]. Lithography masks 1 used in EUV generally comprise a substrate 2 covered by a reflector 3 composed of several alternate layers (also called multilayer stacking) preferably of amorphous silicon and molybdenum, and a protective layer whereon a silicon buffer layer 4 and an absorbent layer 5 are deposited (FIG. 1) [0004]. It has been proposed, in the document WO99/42414, to use the thermal instability of the mechanical stresses of the Mo/Si couple to reduce the stress level in multilayer systems by performing annealing between 100.degree. C. and 300.degree. C. This method is however not reproducible [0010].
Mikami 20150160548 (US equivalent of JP 2015109136) in example 1 forms and EUV maskblank on a substrate, by coating at reflective multilayer of alternating 2.3 nm Mo/4.5nm Si (B doped), where each Si layer is exposed to a nitrogen plasma prior to coating the subsequent Mo layer. The topmost Si layer is then coated with a 2.5 nm Ru capping layer [0146-0180]. Example 4 is similar, but includes the coating of a TaSiN absorber layer and a TaSiON low reflectance layer [0186-0203]. The protective (capping) layer can be a platinum group metal layer such as ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os), iridium (Ir), platinum (Pt), or a compound containing these metals A layer is preferred because it satisfies the above conditions. Among them, it is preferable to form a Ru layer or a Ru compound (RuB, RuZr, etc.) layer. When a Ru compound (capping) layer is formed as the protective layer 13, the Ru content in the protective layer 13 is preferably 50 at% or more, and more preferably 70 at% or more [0093]. The SiN layer can be 0.3 to 1.5 nm and MoN can be 0.2-2.0 nm. The patterning of the absorber layer to form a useful EUV mask is disclosed [0076-0077]. In the present invention, the thickness of the thin film 12b containing Si and N formed on the Si layer 12a is not particularly limited, but the thickness of the thin film 12b is preferably 0.2 to 2.0 nm. When the film thickness of the thin film 12b is 0.2 nm or more, it is preferable in order to exhibit an effect of suppressing the progress of mixing at the layer interface constituting the Mo / Si multilayer reflective film. On the other hand, it is preferable that the film thickness of the thin film 12b is 2.0 nm or less because a decrease in EUV reflectance is slight [0072-0073,0078]. When a thin film containing Mo and N is formed at the interface between the Mo layer and the Si layer (in the Si layer on the Mo layer), the thickness of the thin film is not particularly limited. The thickness is preferably 0.2 to 2.0 nm. When the thickness of the thin film is 0.2 nm or more, it is preferable for exhibiting an action of suppressing the progress of mixing at the layer interface constituting the Mo / Si multilayer reflective film. On the other hand, it is preferable that the thickness of the thin film is 2.0 nm or less because the decrease in EUV reflectance is slight [0072]. The nitridation of the surface of the Si layer or the Mo layer is disclosed. the time for exposing the Si layer surface or the Mo layer surface to the nitrogen-containing atmosphere is set to 60 sec and 600 sec, respectively, but the time for exposing the Si layer surface or the Mo layer surface to the nitrogen-containing atmosphere is limited to this. It can select suitably in the range which satisfies the conditions regarding the nitrogen-containing atmosphere mentioned above. The procedure of exposing the Si layer surface or Mo layer surface to nitrogen gas or a mixed gas of nitrogen gas and an inert gas such as argon under a reduced-pressure atmosphere, as in the procedure shown in the examples described later, When film formation and Mo layer formation are performed using the same chamber, the surface of the Si layer or the surface of the Mo layer is made of nitrogen gas (or a mixed gas of nitrogen gas and an inert gas such as argon). It is important to exhaust the nitrogen gas (or a mixed gas of nitrogen gas and an inert gas such as argon) in the chamber after performing the exposure procedure and before forming the Mo layer or Si layer. Is a preferred procedure. Moreover, this procedure controls the exposure amount of nitrogen gas (or a mixed gas of nitrogen gas and an inert gas such as argon) to the Si layer surface or Mo layer surface, whereby a thin film containing Si and N, Or it is a preferable procedure also in the point that the nitrogen content of the thin film containing Mo and N can be controlled [0075-0076]
Mikami et al. 20130115547 in example 1 forms an EUV mask blank on a substrate by forming a Mo/Si reflective multilayer, where the topmost Si layer was nitride by exposure to a nitrogen containing atmosphere for 600 seconds to form a SiN layer (13), a 2.5 nm Ru protective/capping (16) and then a TaBSiN absorber (17) and TaBSiON low reflectance layer (18) were formed [0172-0269]. Example 2 was similar, forming a Mo/Si reflective multilayer on the substrate, where the topmost Si layer was nitride by exposure to a nitrogen containing atmosphere for 600 seconds to form a 1 nm SiN layer (14) , a 1 nm RuN layer (15), a 2.5 nm Ru protective/capping (16) and then a TaBSiN absorber and TaBSiON low reflectance layer were formed as in example 1 [0270-0290]. ]. A reflective mask is formed by patterning the mask blank using etching [0168-0169] and the result is used in EUV exposure processes to form circuit/semiconductor patterns [0170]. If the content of nitrogen in the second layer 15 is less than 0.1 at %, the above-mentioned effect of containing a very small amount of nitrogen tends to be hardly obtainable. On the other hand, if the content of nitrogen in the second layer 15 exceeds 10 at %, there will be a problem of a decrease in the EUV light reflectance due to excessive nitriding of the Ru protective layer [0058].
Quesnel 20040233535 does not exemplify an example where nitride layers are formed between the Mo and Si layer, an antioxidation layer is provided, a capping layer is provided or an absorber layer is provided and patterned.
With respect to claims 8-14, it would have been obvious to one skilled in the art to modify the process of forming EUV masks with 4.1 nm Mo/2.8 nm Si bilayers taught by Quesnel 20040233535 by nitriding the Mo/Si interfaces by exposing them to nitrogen gas and inducing nitridation where the SiN is 0.3 nm thick and the MoN layer is 0.2 nm thick as taught by Mikami 20150160548 to prevent mixing at the interface as taught in Mikami 20150160548 and to improve reflectivity while keeping mechanical stability up to 350 degrees C as taught at [0032] of Quesnel 20040233535, and to nitride the upper 0.4-1 nm of the topmost silicon layer as taught in Mikami et al. 20130115547 and Mikami 20150160548 and a 1nm RuSiN layer on this to prevent oxidation of the reflective multilayer without a decrease in the EUV reflectance [0058,0065] of Mikami et al. 20130115547 and to provide an absorber on the Ruthenium capping layer as taught in Quesnel 20040233535 at [0004], Kinoshita et al. 20140186752 and the examples of Mikami 20150160548 with a reasonable expectation of forming a useful EUV photomask with enhanced reflectivity and thermal stability. The thickness of the nitridation on the topmost silicon layer is 1 nm (claim 9) and the thickness of the topmost layer including the nitride portion is substantially equal to the thickness of the other silicon layers of the reflective multilayer. The 0.4-1 nm thickness of the nitridation is 14.3 to 35.7 % of the thickness of the 2.8 nm (other) Si layers of the multilayer.
In the response of 11/28/2025, the applicant argues that limitation of the thicknesses of the Mo are the same and the combined thickness of the nitrides layers and the silicon layers are the same throughout the stack. The examiner disagrees, pointing out that the nitridation is facilitated by exposure of the layers to nitrogen, so the thickness of the layers does not change and in the case of the topmost silicon layer, the nitridation is 0.4 to 1 nm thick, rather than 0.3 nm, so the topmost unnitrided silicon layer is thinner than the silicon layer adjacent to it. The examiner has interpreted the claims as only requiring two of the adjacent unnitrided silicon layers to have different thicknesses. Also the scope of the claim language embraces variations in thicknesses which occur during manufacturing of the reflective stack.
In the response of 3/16/2026, the applicant argues that claims 8 requires that the thicknesses of the third (silicon) layer in each multilayer cycle/structure is different while the (nitride) second and fourth layers in each multilayer (cycle/structure) are the same. The claims currently allow for some variance in the thicknesses due to the “substantially equal thickness” language. So while in each of the adjacent (4 layer) multilayer structures/cycles, the silicon layers have “substantially equal thicknesses, the thicknesses are actually slightly different. The trend illustrated in figure 17 and bounded by the language of claim 1 is not obvious over the applied references.
Claims 8-15 are rejected under 35 U.S.C. 103 as being unpatentable over Quesnel 20040233535, in view of Mikami et al. 20130115547 and Mikami 20150160548, further in view of Lu et al. 20050064299.
Lu et al. 20050064299 teaches the use of a hard mask (26,28,30) over a TaSiN/TaSiO (20,22,24) absorber bilayer [0017-0018].
The combination of Quesnel 20040233535, Mikami et al. 20130115547 and Mikami 20150160548 does not include patterning the maskblank using a hardmask formed on the absorber layer.
It would have been obvious modify the processes rendered obvious by the combination of Quesnel 20040233535, Mikami et al. 20130115547 and Mikami 20150160548 by adding a hardmask over the TaSi absorber layer as taught by Lu et al. 20050064299 and patterning the hardmask and absorber to allow it to be used in EUV exposure processes based upon the disclosure of Mikami and in Lu et al. 20050064299 with a reasonable expectation of forming a useful EUV photomask.
The examiner relies upon the response above as no further arguments were directed at this rejection.
Claims 8-14 and 16-20 are rejected under 35 U.S.C. 103 as obvious over Oshemkov et al. 20110255065, in view of Quesnel 20040233535, Mikami et al. 20130115547, Mikami 20150160548 and Fukugami JP 2015-222783
Oshemkov et al. 20110255065 teaches with respect to figure 1, an EUV photomask including 40 pairs of alternating molybdenum (Mo) 130 and silicon (Si) layers 140 (referred to in the following as MoSi layers). The thickness of each Mo layer 130 is 4.15 nm and that of the Si layer 140 amounts to 2.80 nm. In order to protect the multi-layer structure, a capping layer 150 of silicon with a native oxide of 7 nm depth is arranged on top of the structure. In the multi-layer mirror system, the Mo layers 130 act as scattering layers, whereas the silicon layers function as separation layers. For the scattering layers instead of Mo other elements with a high Z number may utilized, such as cobalt (Co), nickel (Ni), tungsten (W), rhenium (Re) and iridium (Ir).The multi-layer structure on the substrate 110 acts a mirror for XUV electromagnetic radiation. In order to become a photolithographic mask 100, a buffer structure 160 and an absorbing structure 170 are additionally deposited on the capping layer 150. The buffer layer 160 may be deposited to protect the multi-layer mirror structure during processing, for example etching or repairing of the absorbing structure 170. Possible buffer structure materials are for example of fused silica (SiO.sub.2), silicon-oxygen-nitride (SiON), ruthenium (Ru), chromium (Cr), and/or chromium nitride (CrN). The absorbing structure 170 comprises a material having a large absorption constant for photons in the XUV wavelength range. Examples of these materials are chromium (Cr) and/or tantalum nitride (CrN). A thickness of about 50 nm is sufficient to absorb essentially all XUV photons 180 incident on the absorbing structure 170. In contrast, the majority of the photons 180 incident on the capping layer 150 is reflected as photons 190. In this context as well as on further positions of this description the term "essentially" means a numeric value of a quantity within its measurement limit [0059-0060]
Fukugami JP 2015-222783 (machine translation attached to previous action) in example 1 coats a substrate with 40 pairs of Mo/Si, a 5nm SiO2 layer (7), a Ru protective layer (3), a 5 nm gas barrier layer (Al2O3) (6) and a TaSi absorber layer and a CrNB conductive backside layer. This is then coated with a resist, which is exposed and patterned and used with a CF4/Cl2 etch to pattern the absorber layer. [0051-0053]. The Mo layer is 2.8 nm thick and the Si layer is 4.2 nm thick [0005]. The gas barrier can be metals such as Ag, Cu, Au, Al, Si, Ni, Fe, Pt, W, Cr, Ti, Ru, Ta, and Mo, SiO2, Al2O3, diamond, diamond like carbon (DLC) or the like and can be 1.5 nm or thicker [0013-0016]. The SiO2 layer (7) can be formed by physical vapor deposition or chemical vapor deposition, thermal oxidation, ion implantation, or diffusion [0017-0021]. The protective layer 3 of the reflective mask blank shown in FIG. 1 is a ruthenium (Ru) layer having a thickness of 2 to 3 nm or a silicon (Si) layer having a thickness of about 10 nm. The protective layer 3 made of Ru can serve as a stopper layer in the processing of the absorption layer 4 and a protective layer against a chemical solution in mask cleaning. When the protective layer 3 is made of Si, a buffer layer may be provided between the absorbing layer 4 and the protective layer 3. The buffer layer is provided to protect the uppermost layer of the multilayer reflective layer 2 adjacent to the bottom of the buffer layer during etching or pattern correction of the absorption layer 4 and is composed of a chromium (Cr) nitrogen compound (CrN) [0042]. The protective layer and the buffer layer play an important role as a layer for preventing damage to the multilayer reflective layer in the dry etching process, mask pattern correcting process, and mask cleaning process when manufacturing the mask. Ruthenium (Ru), which is considered to have high cleaning resistance and etching resistance, is used for the protective layer of the current standard EUV mask blank, and CrN is used for the buffer layer [0006]. The provision of a buffer layer on the protective layer is disclosed and the buffer layer can be CrN and the protective layer can be Ru or silicon [0042].
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The damage mentioned here means oxidation, peeling (peeling), and cracking (crack) in the case of the Ru protective layer, and oxidation and corrosion (etching) in the case of the uppermost layer Si of the multilayer reflective layer. The mechanism is considered as follows. When an EUV light or UV light energy irradiation, a heat treatment such as annealing or baking, a chemical treatment during cleaning, a dry etching treatment, or the like is performed in an environment where oxygen atoms are present, the Ru layer is oxidized and becomes brittle. At the same time, oxygen atoms pass through the Ru layer, and the uppermost Si layer of the multilayer reflective layer is oxidized. When Si is oxidized, it becomes SiO .sub.2 and causes volume expansion. Therefore, cracks are generated in the Ru layer and peeling is generated between the Ru layer and the multilayer reflective layer [0008]. In the reflective mask blank 102 of the present invention, by providing the SiO .sub.2 layer 7 in advance in the blank production stage, the multilayer reflective layer 2 is oxidized even when oxygen is transmitted through the protective layer 3 by the EUV mask production process or EUV exposure. It becomes possible to prevent. Furthermore, it becomes possible to prevent the crack and peeling of the protective layer 3 accompanying it. First, here, a problem relating to the oxidation of the uppermost layer Si of the multilayer reflective layer 2 of the conventional EUV mask blank will be described. Since the uppermost layer Si of the multilayer reflective layer 2 is amorphous, there are many dangling bonds (unbonded hands). When oxygen atoms that have passed through the protective layer 3 approach the state of the blank or mask after the protective layer 3 is formed, it easily reacts with oxygen to form a SiO .sub.2 layer. There was a problem that cracks and peeling occurred. In the reflective mask blank 102 of the present invention, by providing the SiO .sub.2 layer 7 in advance, even if the dangling bond of the uppermost layer Si of the multilayer reflective layer 2 is eliminated and oxygen passes through the protective layer 3 and approaches, Since there is no reaction, oxidation of the multilayer reflective layer 2 cannot occur. Accordingly, since the volume expansion of the uppermost layer Si does not occur, it is possible to prevent the protective layer 3 from being cracked or peeled. The SiO .sub.2 layer 7 can be formed on the uppermost layer Si of the multilayer reflective layer 2 by physical vapor deposition or chemical vapor deposition, thermal oxidation, ion implantation, or diffusion. Another structure of the SiO .sub.2 layer 7 may be a structure in which the outermost surface of the uppermost layer Si of the multilayer reflective layer 2 is subjected to oxygen termination treatment. In this case, methods such as thermal oxidation and annealing are also possible [0033-0038].
Oshemkov et al. 20110255065 does not exemplify an example where nitride layers are formed between the Mo and Si layer, a surface oxidized silicon layer (7) is provided, an antioxidation layer is provided, a capping layer is provided or an absorber layer is provided and patterned.
It would have been obvious to one skilled in the art to modify the process of forming EUV masks with 4.1 nm Mo/2.8 nm Si bilayers taught by Oshemkov et al. 20110255065 by nitriding the Mo/Si interfaces by exposing them to nitrogen gas and inducing nitridation where the SiN is 0.3 nm thick and the MoN layer is 0.2 nm thick as taught by Mikami 20150160548 to prevent mixing at the interface as taught in Mikami 20150160548 and to improve reflectivity while keeping mechanical stability up to 350 degrees C as taught at [0032] of Quesnel 20040233535, to form the silicon oxide layer by surface oxidizing the topmost silicon layer as taught by Fukugami JP 2015-222783 and then forming a 1 nm RuSiN using the process taught in Mikami et al. 20130115547 to prevent oxidation of the reflective multilayer which addresses the peeling and adhesion of the subsequently applied Ru protective/capping layer as taught by Fukugami JP 2015-222783 and to provide an absorber on the Ruthenium capping layer as taught in Quesnel 20040233535 at [0004], Mikami et al. 20130115547 and the examples of Mikami 20150160548 with a reasonable expectation of forming a useful EUV photomask with enhanced reflectivity and thermal stability. The thickness of the nitridation on the topmost silicon layer is 1 nm (claim 9) and the thickness of the topmost layer including the nitride portion is substantially equal to the thickness of the other silicon layers of the reflective multilayer. The 0.3-1 nm thickness of the nitridation is 10.7 to 35.7 % of the thickness of the 2.8 nm (other) Si layers of the multilayer.
The arguments of the applicant fail to appreciate the oxidation of the top 7 nm of the top most silicon layer, which is then nitrides. Therefore the topmost (un- oxidized or nitrided) silicon layer is thinner than the next layer down. The examiner has interpreted the claims as only requiring two of the adjacent unnitrided silicon layers to have different thicknesses. Also the scope of the claim language embraces variations in thicknesses which occur during manufacturing of the reflective stack.
In the response of 3/16/2026, the applicant argues that claims 8 requires that the thicknesses of the third (silicon) layer in each multilayer cycle/structure is different while the (nitride) second and fourth layers in each multilayer (cycle/structure) are the same. The claims currently allow for some variance in the thicknesses due to the “substantially equal thickness” language. So while in each of the adjacent (4 layer) multilayer structures/cycles, the silicon layers have “substantially equal thicknesses, the thicknesses are actually slightly different. The trend illustrated in figure 17 and bounded by the language of claim 1 is not obvious over the applied references.
Claims 1-6 and 8-20 are rejected under 35 U.S.C. 103 as obvious over Oshemkov et al. 20110255065, in view of Quesnel 20040233535, Mikami et al. 20130115547, Mikami 20150160548 and Fukugami JP 2015-222783, further in view of Lu et al. 20050064299.
It would have been obvious modify the processes rendered obvious by the combination of Oshemkov et al. 20110255065, Quesnel 20040233535, Mikami et al. 20130115547, Mikami 20150160548 and Fukugami JP 2015-222783by adding a hardmask over the TaSi absorber layer as taught by Lu et al. 20050064299 and patterning the hardmask and absorber to allow it to be used in EUV exposure processes based upon the disclosure of Mikami and in Lu et al. 20050064299 with a reasonable expectation of forming a useful EUV photomask.
The examiner relies upon the response above as no further arguments were directed at this rejection.
The prior art made of record and not relied upon is considered pertinent to applicant's disclosure.
Ikuta et al. EP 2511945 in example 1 describes the formation of an EUV reflector in examples 1-3, where the topmost Si layer is nitride and then a capping/protective layer is formed [0087-0124].
Kinoshita et al. 20140186752 in example 1 exemplifies a substrate with a CrN backside coating and a Mo/Si reflective multilayer on the front side, where the topmost Si layer (having a thickness of 4.5 nm, intermediate layer 13) was exposed to a nitrogen containing atmosphere for 10 minutes, a 2.5 nm Ru protective/capping layer (layer 14) a 0.5 nm Si thin film (layer 15) which was exposed to air, a TaN absorber layer (layer 16) a TaON low reflectance layer ([0206-0256] and figure 2). .
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After forming the Mo/Si multilayer reflective film, the protective layer is formed, and after forming a Si thin film or Si oxide thin film having a thickness of at most 2 nm on the protective layer, the absorber layer is formed. The Si layer be less than 2 nm, preferably less than 1 nm, 0.8 nm or 0.5 nm [0024,0045,0084,0087-0088]. The intermediate layer is SiN with a nitrogen content of 0.5-15 at%. It has a thickness of 0.2 to 2.5 nm of the 2-4.8 nm of the topmost Si layer, is formed by nitridation of the top surface and prevents oxidation of the reflective multilayer [0123-0150]. The intermediate layer (13) can be formed as a bilayer (21/22) as illustrated in figure 3. The first layer (21) is a SiN layer and the second layer (22) is RuSiN. The double layer structure has the advantage of no deterioration in reflectivity due to the nitrogen content of the silicon film. The total thickness of the bilayer is 0.2 to 2.5 nm and the first layer can be 0.1 to 2.4 nm and the second layer can be 0.1-2.4 nm [0151-0175]. A reflective mask is formed by patterning the mask blank using etching [0203] and the result is used in EUV exposure processes to form circuit/semiconductor patterns [0204].
Any inquiry concerning this communication or earlier communications from the examiner should be directed to Martin J Angebranndt whose telephone number is (571)272-1378. The examiner can normally be reached 7-3:30 pm EST.
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If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Mark F Huff can be reached on 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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MARTIN J. ANGEBRANNDT
Primary Examiner
Art Unit 1737
/MARTIN J ANGEBRANNDT/Primary Examiner, Art Unit 1737 March 25, 2026