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 Rejection of the previous office action not repeated below are withdrawn based upon the amendments and arguments of the applicant.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 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.
Claim 1,4,9,11-13,15-17 and 20 are rejected under 35 U.S.C. 112(b) or 35 U.S.C. 112 (pre-AIA ), second paragraph, as being indefinite for failing to particularly point out and distinctly claim the subject matter which the inventor or a joint inventor (or for applications subject to pre-AIA 35 U.S.C. 112, the applicant), regards as the invention.
Independent claims 1,12 and 15 should clearly describe that the reflectance of the light shielding film is measured 10 times at 49 different points using a light with a wavelength of 193 nm (emphasis added)
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 1,4,9 and 11 are rejected under 35 U.S.C. 102(a)(1) as being fully anticipated by Kageyama et al. 20150301442
Kageyama et al. 20150301442 teaches in example 1, a substrate with a 15 nm CrO layer (71% Cr) formed upon it, followed by a 185 nm CrN layer (86% Cr) which was sputtered and then heated in the presence of oxygen at 140 degrees C for 20 minutes to yield a 1.9 nm CrONH film (72% Cr) with an amorphous or microcrystalline structure and an RMS surface roughness of 0.095 nm [0159-0181]. Example 2 was formed similarly (71% Cr in CrOH, 86% Cr in CrNH, 79.1% Cr in CrONH) , but was heated at 120 degrees C for 15 minutes which resulted in a roughness of 0.090 nm [0182-0194]. Example 3 was formed similarly, but was heated at 160 degrees C for 40 minutes which resulted in a roughness of 0.100 nm [0195-0212].
The claims specify the roughness in terms of product of the absolute value of the skewness and kurtosis being less than 6. Skewness is a measure of the degree of bias of the surface roughness relative to a mean. If there is no bias, the Rsk value is zero Kurtosis is a measure of the narrowness or width of the roughness profile with 3 being a Gaussian, broader distributions being less than 3 and narrower (Poisson like) distributions being more than 3 ( hus: www. keyence coniss/producis/mucrosecane/roug iess/sgrlace/skut- kuriasis.iso ). This is achieved by mild heating of the oxygen or nitrogen containing light shielding layer at 150-330 degrees C for the relatively short period of 5-30 minutes followed by (rapid) cooling with sprayed water (claim 13). The specification uses CrN as the light shielding layer
The position of the examiner is that the mild heating at 120,140 or 160 C for 15-40 minutes in the cited examples Kageyama et al. 20150301442 are demonstrated to reduce the roughness of the CrN layer and the similarity in these treatments with those of the instant specification yields a CrN layer with a surface roughness within the scope of coverage sought. The rapid cooling is not considered to be critical at these low temperatures where crystalline state is locked in quickly by natural cooling. The applicant is invited to refute this with evidence to support their position.
In response to the arguments of 3/17/2025, the light shielding structure of Kageyama et al. 20150301442 has three layers and the middle layer has a higher Cr content as evidenced by the disclosure of the references. The examiner notes that the light shielding layer “comprises a first light shielding layer and a second light shielding layer” and so is open to the presence of other, unrecited layers. Also the topmost layer has the additionally function of reducing reflectivity of the light shielding structure and so may rightly be considered a separate layer from the light shielding bilayer.
In the arguments of 7/9/2025, the applicant argues the roughness metrics. These do not appear in claims 1,2,4,5,11-13, so the arguments are not commensurate in scope with the coverage sought. Further, the heat treatment of the references and the instant application result in an amorphous/microcrystalline structure in the light shielding layer which is held to inherently include the surface roughness recited in the claims. The applicant argues that the data in the application supports the rapid cooling being required. The (comparative) examples do not include an example where the rapid cooling is not used. Additionally, the roughness in the examples is significantly larger than the roughnesses reported in the reference, so it is not clear that the comparative data in the instant specification is equal or preferable to a direct comparison with the prior art.
In response of 11/25/2025, the applicant argues that Kageyama et al. does not report Rsk or Rku values and that it does not follow that the smooth profiles have Gaussian height distributions or negative skew as the oxide formation uses a different process without the rapid cooling of the specification. The examiner agrees that the oxidation processes used in the instant specification (wet processes) and Kageyama et al. are different, but notes that both are oxidizing the surface of CrN layers, so the differences in the results of the treatments are not as different as asserted by the applicant. The heating and rapid cooling in the instant specification prevents crystallization of the CrN layer, so it has an amorphous character as does the oxidized CrN layer of Kageyama et al. The applicant has chosen to characterize the surface using a less common measurement and should therefore bear the burden of this choice and providing declaration evidence regarding alleged differences in the surface topography.
The applicant argues that the optical density and reflectance uniformity of the film is not described and asserts that as forced cooling weas not used, the uniformity might not be as high as the process used by the applicant. First, the claims are not produce by process claims, so the exact process is not required and the claims have not been evidenced to be tied as closely to the processing of the specification as asserted by the applicant. Claims 1 and 12 recite 10 measurements, but do not require these to be made at different positions across the surface. It is not even clearly that claim 4 requires 49 different measuring points. Also the heating at 120, 140 and 160 degrees C is not that much below the 200 degrees C used in the examples of the instant specification and without the rapid cooling allow the relaxation/reduction in stress to occur over as longer period without allowing crystallization. This is certainly true for the heating at 160 degrees C for 40 minutes in example 3. The additional time for relaxation and oxidation assures the Gaussian distributions. The rejection stands.
In response to the arguments of 7/9/2026, the smoothness of the surface in the cited examples is 0.100 nm or less which is well below the 4.7 nm maximum peak height recited in the claims. The light shielding layers are annealed in the presence of oxygen resulting in an amorphous/microcrystalline structure and oxidized surface with a high smoothness. While Kageyama et al. 20150301442 does not report the reflectance of reflectance variation, the position of the examiner is the thickness of the CrN layer is 185 nm which results in a high optical density (no light is getting through) which would preclude significant variation in the optical density and the thermal treatment which results in an amorphous/microcrystalline state and high uniformity in composition and thickness as indicted in the low roughness of the surface. The oxide surface layers inherently act as antireflection layers which reduces the reflectivity and the variation in the reflectivity. The applicant refers to the inventive and comparative data. Comparative example 1 does not perform any heating. Comparative examples 2 and 2 heat the maskblank at 250 degrees for 10 minutes before air cooling, which 90 degrees or more higher than examples 1-3, which based upon the trend toward increased roughness with higher temperatures in the examples and the 0.132 nm surface roughness of comparative example 3 of Kageyama et al. 20150301442 when 200 degree heating is used would be expected to have a higher roughness. The oxidized CrN surface layer of Kageyama et al. 20150301442 inherently acts as an antireflection layer. The anti-reflective surface will reduce the reflectance from the top surface as well as the variance in the reflectance.
Examiner notes that the thicknesses of the layers exemplified in the instant specification differ from those exemplified in the reference. The rejection are withdrawn as the backside is not patterned.
Claims 1,4,9 and 11 are rejected under 35 U.S.C. 102(a)(1) as being fully anticipated by Kageyama et al. 20150301442 as evidenced by Kim et al. 20160202611 and Tsuchiya et al. 5536603
Kim et al. 20160202611 teaches with respect to figure 7, aa protective layer 140 may be further formed on a surface of the light-shielding layer pattern 115. For example, the protective layer 140 may be formed on a sidewall and a top surface of each light-shielding layer pattern 115. In example embodiments, the protective layer 140 may be formed by oxidizing and/or nitriding the surface of the light-shielding layer pattern 115. For example, a plasma treatment using oxygen (O.sub.2) and nitrogen (N.sub.2) as a reactive gas may be performed on the light-shielding layer pattern 115 to form the protective layer 140. If the light-shielding layer pattern 115 includes chrome, the protective layer 140 may include, e.g., chrome oxide, chrome nitride, and/or chrome oxynitride. The protective layer 140 may also serve as an anti-reflective layer during an exposure process using the photomask. Additionally, the protective layer 140 may prevent the light-shielding layer pattern 115 from being damaged by, e.g., an acid solution used in a re-pellicle process for a recycle of the photomask [0080-0083].
Tsuchiya et al. 5536603 teaches with respect to figure 10A, a chrome layer having a thickness of about 1000.ANG. is formed on a quartz substrate 1 by sputtering, and light-shielding film patterns 3 are formed by patterning the chrome layer. The light-shielding film patterns 3 each have a two-layered structure including a chrome layer 3a and a chrome oxide film 3b obtained by oxidizing the surface of the chrome layer 3a (col 8/lines 14-20).. As shown in FIG. 3A, shielding film patterns 3 are formed on a transmitting substrate 1 of quartz or the like, and each have a laminated structure wherein a chrome oxide film 3b is formed on the surface of a chrome layer 3a as an antireflection film. Phase shifters 2E and 2F each constituted by an LPD film, are provided alternately between adjacent light-shielding film patterns on the exposed surface of the substrate 1 (col 5/lines 34-41). A light-shielding film pattern 3 of a two-layered structure including a chrome film 3a and a chrome oxide film 3b formed thereon, is provided on a quartz substrate 1. The thickness of the substrate 1 ranges from 0.09 to 0.125 inch, that of the chrome film 3a is 600.ANG., and that of the chrome oxide film 3b ranges from 300 to 400.ANG.. Positive photoresist is applied to the surface of the shielding film pattern 3 to form a resist layer 4. In this embodiment, the thickness of the resist layer 4 is about 300 nm and a factor in determining the thickness of a phase shifter layer 2 formed on the resist layer 4 (col. 9/lines 26-36)
In addition to the basis above, the examiner cites Kim et al. 20160202611 and Tsuchiya et al. 5536603 to support the position that the oxidized CrN surface layer of Kageyama et al. 20150301442 inherently acts as an antireflection layer. The anti-reflective surface inherently will reduce the reflectance and the variance in the reflectance.
Claims 1,4,9,11-13,15-16 and 20 are rejected under 35 U.S.C. 103 as being unpatentable over Nam et al. 20160291451, in view of Yamada et al. KR 20150108354 , Suzuki et al. WO 2006123630, Kim et al. 20160202611 and Tsuchiya et al. 5536603.
Nam et al. 20160291451 in example 8 teaches a maskblank including a MoSiN phase shift layer, a CrON layer formed by puttering in 5sccm Ar/10 sccm N2 and 5 sccm NO, Cr48N30O22) and a CrN layer formed by sputtering in 3 sccm Ar and 5 sccm N2 (Cr58N48) [0065-0109, particularly 0084,0085,0106] The phase-shift film 104 may selectively undergo thermal treatment at a temperature of 100° C. to 500° C. so as to control its resistance to chemicals and flatness [0034]. The light-shielding film 106 may selectively undergo thermal treatment. At this time, temperature for this thermal treatment may be equal to or lower than that for the under phase-shift film 104 [0050]. For the evaluation about SC-1, the phase-shift films were cleaned three times at about 45° C. for 20 minutes with a solution, where NH4OH, H2O2 and H2O are mixed at a volume ratio of NH4OH:H.2O2:H2O=1:1:5. Then, change in the phase-shift degree and the transmissivity between before and after the cleaning process was measured. For the evaluation about SPM, the phase-shift films were cleaned three times at about 90° C. for 10 minutes with a solution, where H2SO4 and H2O2 are mixed at a ratio of H2SO4:H2O2=9:1. Then, change in the phase-shift degree and the transmissivity between before and after the cleaning process was measured [0077-0078]. At a portion where the phase-shift film 104 and the light-shielding film 106 are stacked, an optical density is 2.5˜3.5 and preferably 2.7˜3.2 with respect to the exposure light having a wavelength of 193 nm or 248 nm, and a surface reflectivity is 20%-40% and preferably 25%-35% [0071]. In the comparative example 3, a light-shielding layer of chromium nitride (CrN) was formed to a thickness of 485 Å on the phase-shift film having a transmissivity of 20% under process gas of Ar:N.sub.2=3 sccm:5 sccm and process power of 0.8 kW, and then an anti-reflective layer of chromium oxide nitride (CrON) was formed to a thickness of 120 Å under process gas of Ar:N.sub.2:NO=5 sccm:10 sccm:2 sccm and process power of 0.8 kW.
Suzuki et al. WO 2006123630 (machine translation attached) teaches a metal:silicon with nitrogen and/or oxygen which is subjected to a heat treatment and rapid/forced cooling (abstract). The present inventors have advanced research and development focusing on the cooling process after the heat treatment. As a result, the cooling means that can cool at the in-plane uniform cooling rate in the cooling process after the heat treatment. In addition, it is possible to further reduce variations in optical characteristics (phase difference and transmittance) for products that meet the current strict specifications by performing cooling treatment with a cooling means that can be forcedly cooled. Surprisingly, it was found that this is an effective means for realizing the next higher specification (required specification) [0010].
A cooling means that can cool the light semi-transmissive film immediately after the heat treatment at an in-plane uniform cooling rate and can be forcibly cooled” includes, for example, cooling. plate Is mentioned. According to the cooling plate, the cooling temperature history can be almost the same at the periphery and the center of the substrate [0030]. the hot plate 30 was heated at a hot plate temperature of 300 ° C for 10 minutes, and then the cooling plate 31 was cooled at a cooling plate temperature of 15 ° C for 5 minutes (cooling) Speed: -56 ° CZ min). The surface temperature of the light semi-transmissive film 41 in the phase shift mask blank immediately after the cooling treatment was 22 ° C. which is the same as the room temperature. The film surface temperature of this light translucent film was measured by thermography [0060]. In addition, a light shielding film may be formed on the light semi-transmissive film for the purpose of blocking the exposure wavelength. As the material of the light-shielding film, for example, when the material different from the etching characteristics of the light translucent film is molybdenum, chromium, chromium oxide, chromium nitride, chromium carbide, chromium fluoride A material containing at least one of them is preferred. In this case, the heat treatment and the rapid cooling treatment may be performed after the light shielding film is formed [0083].
Yamada et al. KR 20150108354 (machine translation attached) teaches a substrate coated with a sputtered 2.3 nm CrN layer which was then baked at 200 degrees for 15 minutes to oxidize the surface. This was cooled and the photoresist layer was coated on the surface [0213-0224]. The cleaning step of the substrate before the resist coating in the lithography step, a physical cleaning tool such as a megasonic nozzle or a brush, and a cleaning tool such as APM (ammonia and water) or SPM A cleaning process such as RCA cleaning is applied, for example [0005].
Nam et al. 20160291451 does not exemplify the heating, cooling treatment of the light shielding layer with an oxidizer or the use of rinsing after the washing/cleaning step.
With respect to claims 15-16 and 20, it would have been obvious to one skilled in the art to modify the process of forming the mask of example 8 of Nam et al. 20160291451 by heating, the light shielding bilayer with the upper CrN layer in the presence of oxygen, cooling the light shielding bilayer as taught in Suzuki et al. WO 2006123630 to form an oxidized surface on the CrN layer to improve adhesion of resists as taught by Yamada et al. KR 20150108354, form an antireflective surface as taught in Kim et al. 20160202611 and Tsuchiya et al. 5536603 and reduce variations in optical characteristics (phase difference and transmittance) for products as taught at [0010] of Suzuki et al. WO 2006123630, noting that Nam et al. specifically describes the heating of the light reflective layer at [0050] and the heating of the phase shift layer at [0034] and performed the cleaning as taught in Nam et al. at [0077-0078] and Yamada et al. KR 20150108354 with a reasonable expectation of forming a useful photomask blank ready for a resist to be applied.
With respect to claims 1,4,9 and 11, the mask blanks formed meets the limitations of the claims, noting the thicknesses and compositions of the lower and upper layer are within the ranges taught in the instant specification as is the surface oxidation of the upper CrN layer. The heat treatment with the rapid cooling is clearly disclosed as reducing variations in optical characteristics (phase difference and transmittance) for products that meet the current strict specifications by performing cooling treatment with a cooling means that can be forcedly cooled. Surprisingly, it was found that this is an effective means for realizing the next higher specification (required specification) [0010] including the in-plane uniform cooling rate as taught at [0030] of Suzuki et al. WO 2006123630 which points to a reduction in the in-plane variations in the optical characteristics of the mask. The surface oxidation inherently acts as an anti-reflection layer which reduces the reflectivity and with it the variance in the reflectivity.
With respect to claims 12-13, it would have been obvious to pattern the light shielding layers and phase shift layer of the maskblanks resulting form the processing of Nam et al. 20160291451, Yamada et al. KR 20150108354 , Suzuki et al. WO 2006123630, Kim et al. 20160202611 and Tsuchiya et al. 5536603 discussed above by patterning the masks as taught in the references, including Nam et al. 20160291451 with a reasonable expectation of forming a patterned photomask useful in exposing resists and forming semiconductor/electronic devices.
The applicant argues that the higher Cr/metal content of the upper layer is not taught in the references. Nam et al. specifically describes the lower CrON layer as having a 48% Cr content and the 5 nm upper CrN layer as having a 58% Cr content and having a reflectivity of 33% and an OD of 2.95 at 193 nm [0106]. The heating treatments of Suzuki et al. WO 2006123630 will reduce variation in the optical properties of the light shielding layers and is embraced by the thermal treatments described in Nam et al. 20160291451 at [0034,0050].
The applicant argues that Nam’s CrN layer is thick, but it is only 5 nm thick, which is not much more than the 2.3 nm of Yamada et al. KR 20150108354, which evidences the oxidation of the CrN layer. As the SC-1 is a cleaning solution and Yamada et al. KR 20150108354 establishes that it is known to be used on the CrN surface of a photomask, it is not impermissible hindsight. The oxidation of the surface during the heating and the cleaning agents will reduce the reflectivity to within the 20-28% range recited in the claim. The applicant asserts that the particular combination of conditions or performance achieved by the applicant, but the claims recite few specific step, which are all embraced by the teachings of the references. The rapid colling of the MoSi (O and/or N) phase shift layer in Suzuki et al. WO 2006123630 is reasonably applicable to the MoSiON phase shift layer of Nam. As the changes discussed in the rejection are clearly taught in the prior art, they are not impermissible hindsight and Nam et al. specifically describes heat treatment at [0034,0050}. The applicant argues there is an improvement in the smoothness of the surface due to the heating and cooling. The motivation needs not be the same as that of the applicant, the light resistance to exposure light, (2) chemical resistance, (3) low film stress, and (4) in-plane uniformity of optical properties (phase difference, transmittance) are described at [0006-0010] of Suzuki et al. WO 2006123630 as due to the heating and rapid cooling. The forced cooling resulting is uniform cooling across the surface [0013-0017] of Suzuki et al. WO 2006123630. The oxidation of the surface is expected based upon the teachings of Yamada et al. KR 20150108354 and the rapid cooling does not allow for crystallization to occur, so the surface will be smooth and flat. The rejection stands.
In the response of 3/11/2026, the applicant argues that Suzuki et al. discloses reducing variations in the MoSi phase shift layer, but does not discuss the reducing the variation in the reflectance and optical density of a mask with the recited light shielding bilayer. The position of the examiner is that the thermal treatment with rapid cooling which is described as reduction in-plane variation of the optical properties [0010,0030] in Suzuki et al. WO 2006123630 when practiced after the light shield layers have been applied as discussed at [0083] would also reduce the in plane variation in the light shielding layers as the cooling of these would also be uniform across the surface. This addresses variance in reflectivity and optical density, noting that the phase shift layer also contributes to the optical density. Nam et al. does not describe the reduction in the variance of the measurements and is not relied upon to do so, noting that the rejection relies upon Suzuki et al. WO 2006123630, who discusses reduction in in-plane variation and the antireflection properties of the surface oxidized taught by Kim et al. 20160202611 and Tsuchiya et al. 5536603 which disclose reducing the reflectivity, which also would reduce the variance in the reflectivity and the roughness of the surface.
Claims 1,4,9,11-13,15-17 and 20 are rejected under 35 U.S.C. 103 as being unpatentable over Nam et al. 20160291451, in view of Yamada et al. KR 20150108354 , Suzuki et al. WO 2006123630, Kim et al. 20160202611 and Tsuchiya et al. 5536603, further in view of Nagamura et al JP 2000330262 and Kageyama et al. 20150301442.
Nagamura et al JP 2000330262 teaches conventional cleaning in step 1, a mixed solution of high-temperature sulfuric acid and hydrogen peroxide solution is used to decompose organic substances such as resist and solvent residues present on the photomask surface and to remove metal impurities. To clean the photomask. In this step, the wettability of the mask surface is improved and the efficiency of subsequent cleaning is increased. Next, in step 2, the chemicals such as sulfuric acid are removed by rinsing with pure water Even after this step, sufficient rinsing with pure water is required as shown in step 4. Finally, in the step 5, the photomask rinsed with pure water is dried. In the process of Step 3, cleaning using megasonic or other ultrasonic waves is performed using pure water alone or using pure water with a detergent without using a mixed solution of ammonia and hydrogen peroxide. May be performed [0004-0008]
The combination of Nam et al. 20160291451, Yamada et al. KR 20150108354 , Suzuki et al. WO 2006123630, Kim et al. 20160202611 and Tsuchiya et al. 5536603 does not teach the process of claims 15-17 and 20 where the mask blanks are rinsed after treatment with the cleaning solution or that the oxidation of the surface reduces the surface roughness to below 1 nm.
With respect to claims 15-17 and 20, it would have been obvious to one skilled in the art to modify the processes rendered obvious by the combination of Nam et al. 20160291451, Yamada et al. KR 20150108354 , Suzuki et al. WO 2006123630, Kim et al. 20160202611 and Tsuchiya et al. 5536603 by rinsing with water as is conventional after using a cleaning solution as established in Nagamura et al JP 2000-330262 at [0004-0008] and that the resulting oxidized CrN surface would have a roughness of less than 1 nm based upon the evidence in Kageyama et al. 20150301442 with a reasonable expectation of forming a maskblank ready for application of a resist.
With respect to claims 1,4,9 and 11, the mask blanks formed meets the limitations of the claims, noting the thicknesses and compositions of the lower and upper layer are within the ranges taught in the instant specification as is the surface oxidation of the upper CrN layer. The heat treatment with the rapid cooling is clearly disclosed as reducing variations in optical characteristics (phase difference and transmittance) for products that meet the current strict specifications by performing cooling treatment with a cooling means that can be forcedly cooled. Surprisingly, it was found that this is an effective means for realizing the next higher specification (required specification) [0010] including the in-plane uniform cooling rate as taught at [0030] of Suzuki et al. WO 2006123630 which points to a reduction in the in-plane variations in the optical characteristics of the mask. The surface oxidation inherently acts as an anti-reflection layer which reduces the reflectivity and with it the variance in the reflectivity.
With respect to claims 12-13, it would have been obvious to pattern the light shielding layers and phase shift layer of the maskblanks resulting from the processing of Nam et al. 20160291451, Yamada et al. KR 20150108354 , Suzuki et al. WO 2006123630, Kim et al. 20160202611, Tsuchiya et al. 5536603, Nagamura et al JP 2000330262 and Kageyama et al. 20150301442 discussed above by patterning the masks as taught in the references, including Nam et al. 20160291451 with a reasonable expectation of forming a patterned photomask useful in exposing resists and forming semiconductor/electronic devices.
The prior art made of record and not relied upon is considered pertinent to applicant's disclosure.
Morishige 6136096 teaches the oxidation of a Cr film of a mask by the exposure to ozone to reduce the reflectivity from about 40% to 15% or less (4/63-5/2, 5/48-6/21).
Kong et al. 20220244633 teaches the formation of a chromium oxide barrier layer on the chromium layer of a photomask by heating the chromium layer to 200-500 degrees C in the presence of oxygen, where the barrier layer is formed only on the light shielding layer. The oxidation of the surface prevents chromium migration which can result in surface roughness in the light shielding film. [0017,0055-0056]. The oxidation can also take place at lower temperatures, such as 60-80 degrees C.
Inazuki et al. 20200192215 teaches the chromium-containing film had a thickness of 44 nm. The composition of the chromium-containing film was analyzed in the thickness direction by an XPS. A region (C) that is a surface portion remote from the substrate of the chromium-containing film was formed by natural oxidization, and had a composition continuously varied in the thickness direction within about 1/10 of the whole of the thickness from the side remote from the substrate of Cr:O:C=40:50:10 (atomic ratio) to the substrate side of Cr:O:C=60:20:20 (atomic ratio). Further, a region (A) that is the remainder portion located at the substrate side apart from the region (C) was formed, and had a composition continuously varied in the thickness direction from the side remote from the substrate of Cr:O:C=60:20:20 (atomic ratio) to the interfacial surface in contact with to the substrate of Cr:O:C=80:10:10 (atomic ratio). The results of the compositional analysis are shown in FIG. 4A. The chromium-containing film had a transmittance of 0.43% (an optical density OD of 2.37) at a wavelength of 193 nm, and thus, the total optical density OD of the halftone phase shift film and the chromium-containing film was 3.09 [0089]. The chromium-containing film had a thickness of 46 nm. The composition of the chromium-containing film was analyzed in the thickness direction by an XPS. A region (C) that is a surface portion remote from the substrate of the chromium-containing film was formed by natural oxidization, and had a composition continuously varied in the thickness direction within about 1/10 of the whole of the thickness from the side remote from the substrate of Cr:O:C:N=40:50:10:0 (atomic ratio) to the substrate side of Cr:O:C:N=60:20:20:0 (atomic ratio). Further, a region (B) that is located at the substrate side apart from the region (C) was formed, and had a constant composition of Cr:O:C:N=60:20:20:0 (atomic ratio) in the thickness direction within about 5/10 of the whole of the thickness, and a region (A) that is the remainder portion located at the substrate side apart from the region (B) was formed, and had a composition continuously varied in the thickness direction from the side remote from the substrate of Cr:O:C:N=60:20:20:0 (atomic ratio) to the interfacial surface in contact with to the substrate of Cr:O:C:N=75:11:11:3 (atomic ratio). The results of the compositional analysis are shown in FIG. 6A. The chromium-containing film had a transmittance of 0.42% (an optical density OD of 2.38) at a wavelength of 193 nm, and thus, the total optical density OD of the halftone phase shift film and the chromium-containing film was 3.10 [0107]. The chromium-containing film had a thickness of 51 nm. The composition of the chromium-containing film was analyzed in the thickness direction by an XPS. A region (i) that is a surface portion remote from the substrate of the chromium-containing film was formed by natural oxidization, and had a composition continuously varied in the thickness direction within about 1/10 of the whole of the thickness from the side remote from the substrate of Cr:O:C:N=40:50:10:0 (atomic ratio) to the substrate side of Cr:O:C:N=60:20:20:0 (atomic ratio). Further, a region (ii) that is located at the substrate side apart from the region (i) was formed, and had a constant composition of Cr:O:C:N=60:20:20:0 (atomic ratio) in the thickness direction within about 4/10 of the whole of the thickness, and another region (iii) that is the remainder portion located at the substrate side apart from the region (ii) was formed, and had a constant composition of Cr:O:C:N=42:29:15:14 (atomic ratio) in the thickness direction. The composition was discontinuously varied from the region (ii) to the region (iii). The results of the compositional analysis are shown in FIG. 8A. The chromium-containing film had a transmittance of 0.45% (an optical density OD of 2.35) at a wavelength of 193 nm, and thus, the total optical density OD of the halftone phase shift film and the chromium-containing film was 3.07 [0125]. The region (C) may be a region formed by oxidizing surface portion of the chromium-containing film at the side remote from the substrate by natural oxidation, heat treatment, cleaning, and so on. In the region (C), a difference between the maximum oxygen content (at %) and the minimum oxygen content (at %) is preferably at least 10, more preferably at least 15. The upper limit of the difference of oxygen content is normally up to 50, and preferably up to 45 [0054].
Nozawa et al. 20130316271 teaches preparing a mask blank having a tantalum light-shielding film (30) made of a material containing tantalum as a main metal component on a transparent substrate (1). The light-shielding film is etched to form a light-shielding film pattern. The film pattern is treated with hot water or ozone water to form a highly oxidized layer (4) with an oxygen content of 60% or more as a surface layer of the light-shielding film pattern, where the film has a structure in which light-shielding and front-surface anti-reflection layers (2, 3) are laminated from the substrate (abstract)
Rolfson 6183915 teaches that chromium and other reflective metals are commonly used as the opaque regions in reticle fabrication. Such material is highly light reflective, which can further cause problems with respect to the pattern being produced in the photoresist on the wafer. One technique used to minimize the reflection is to provide an antireflective layer over the chromium layer prior to fabrication of the pattern on the reticle. One example class of antireflective materials is chromium oxides, either deposited onto the reticle or formed by oxidizing the outer portion of a deposited chromium layer. Unfortunately, the preferred embodiment etching of all the transparent areas and phase shift areas in the '035 disclosure also resulted in etching of at least some of the antireflective coating material from some of the opaque regions (col 2/lines 53-67)
Nam et al. 20180335691 teaches that the light-shielding film 106 may include a single layer or multi layers. For example, when the light-shielding film 106 has a two-layered structure, a lower layer may be provided as a light-shielding film for shielding the exposure light, and an upper layer may be provided as an anti-layered film for reducing reflectivity of exposure light [0049]. The light-shielding film 106 may include a single layer or multi layers. For example, when the light-shielding film 106 has a two-layered structure, a lower layer may be provided as a light-shielding film for shielding the exposure light, and an upper layer may be provided as an anti-layered film for reducing reflectivity of exposure light [0053]. Next, the light-shielding film 106 having a two-layered structure of a chrome (Cr) compound was formed using the chrome (Cr) target on the phase-shift film 104. The lower layer of the light-shielding film 106 adjacent to the phase-shift film 104 was formed as a film of CrN having a thickness of 28 nm by injecting a process gas of Ar:N2=5 sccm:9 sccm and supplying a process power of 1.4 kW. The upper layer of the light-shielding film 106 was formed as a film of CrON having a thickness of 10 nm by injecting a process gas of Ar:N2:NO=3 sccm:10 sccm:5 sccm and supplying a process power of 0.6 kW. The light-shielding film 106 showed an optical density of 3.05 and a reflectivity of 30% with respect to the exposure light having a wavelength of 193 nm [0072].
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MARTIN J. ANGEBRANNDT
Primary Examiner
Art Unit 1737
/MARTIN J ANGEBRANNDT/Primary Examiner, Art Unit 1737 July 8, 2026
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