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 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 1-20 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.
The claims should clearly recite the first pellicle mounted to the substrate bearing the mask layer through a frame of the first pellicle having a pellicle membrane and that the defocusing is relative to the pellicle membrane location.
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 1-7 and 15-18 are rejected under 35 U.S.C. 103 as being unpatentable over Brouns et al. 20180314150, in view of Tanaka JP 2021015027 and Kim et al. KR 101738887.
Brouns et al. 20180314150 teaches an EUV transparent pellicle 19 may be removed from the mask MA using the pellicle removal and attachment tool and then passed to the mask inspection tool without attaching an alternative pellicle to the mask. Following inspection of the mask MA by the mask inspection tool the pellicle frame 17 and EUV transparent pellicle 19 may be re-attached to the mask by the pellicle removal and attachment tool (or a new pellicle frame 17 and EUV transparent pellicle 19 may be attached). Although this approach allows inspection of the mask it includes the disadvantage that the mask is not protected by a pellicle during inspection of the mask, or during transfer to and from the mask inspection tool. The mask inspection tool may for example have a less closely controlled clean environment than the environment of the pellicle removal and attachment tool or the environment of a lithographic apparatus. A contamination particle could for example adhere to the mask MA after inspection and before the pellicle frame 17 and EUV transparent pellicle 19 are attached to the mask. Since this occurred after mask inspection the contamination particle would not be detected and would lead to defects in patterns projected on substrates. This disadvantage is avoided by the method shown in FIG. 4 because the mask MA is protected by a pellicle during mask inspection and during transfer to and from the mask inspection tool. The mask MA is only unprotected during swapping between the EUV transparent pellicle and the alternative (e.g. DUV-transparent) pellicle, which is a small part of the process. The environment provided in the pellicle removal and attachment tool may be closely controlled (e.g. more closely controlled than other environments) given that this is the only environment in which mask MA is unprotected [0131]. The inspection may determine the number and/or size and/or shape of particles and/or holes in the pellicle. If particles are found or if a hole is found which gives rise to an increased risk of pellicle breakage, then the pellicle assembly is removed and replaced with a new pellicle assembly. For example, if a hole is found in the pellicle then this may give rise to an unacceptable risk of pellicle breakage when pumping the mask assembly down to a vacuum or venting the mask assembly (significant pressure differences on either side of the pellicle may occur during pumping or venting). Replacing the pellicle assembly prevents such a breakage from occurring [0203]
EUV reflection measurements—EUV radiation is directed onto the pellicle and a sensor monitors for localized variations in the reflection of the pellicle. A localized variation in EUV reflection is indicative of a deterioration (or other change) of capping material on the pellicle. This deterioration or change of the capping material is indicative of a breakage risk of the pellicle. If such a deterioration or other change is found then the pellicle assembly is removed from the mask and is replaced. EUV reflection measurements may also monitor for global variations in the reflection of the pellicle. Again, a variation in EUV reflection (compared with a reference value of reflection, which may be a previously measured value) is indicative of a deterioration or other change of the capping material on the pellicle. Again, if such a variation is seen then the pellicle assembly is removed from the mask and replaced. EUV transmission measurements (pellicle in situ on mask)—an EUV radiation beam is directed onto the pellicle. EUV radiation which passes through the pellicle is reflected by the mask and passes back out through the pellicle. This reflected EUV radiation is monitored. The monitoring may be done by measuring and mapping the EUV radiation before the mask assembly is used, and then comparing a subsequently measured map with the initial map. Differences between the maps indicate either a change in the pellicle or a change in the mask. The nature of the differences may be used to discriminate a change of the pellicle from a change of the mask. If a significant change of the pellicle is seen then the pellicle assembly may be replaced. If a significant change of the mask is seen then the mask may be cleaned [0198-0199]
Inspection of the pellicle when the pellicle assembly has been removed from the mask may comprise one or more of the following methods: EUV transmission measurements, EUV reflection measurements, birefringence measurements, ellipsometry, Fourier transform infra-red spectroscopy, Raman spectroscopy, X-ray reflection measurements, microscope inspection, resonance measurements, measurement of pellicle displacement due to pressure difference, pellicle deflection during pumpdown or venting, scanning heat load measurements, frame deformation measurements. The majority of these are as described above. Those which have not been described above, or which may take a different form when the pellicle assembly has been removed from the mask, are described below: EUV transmission measurements (pellicle assembly removed from mask)—an EUV radiation beam is directed onto the pellicle and the amount of EUV radiation which is transmitted by the pellicle is measured using a sensor located on an opposite side of the pellicle. This allows localized changes in transmission of the pellicle to be measured. For example, a test criterion for a pellicle may be transmission of 85% plus or minus 2%. If the transmission of the pellicle is higher than this (e.g. 87% or more) then this may indicate that a loss or material (e.g. capping layer material) from the pellicle has occurred. In this situation an increased risk of pellicle failure may arise, and the pellicle assembly may therefore be replaced with a new pellicle assembly. If the transmission of the pellicle is lower than the test criterion (e.g. 83% or less) then this may indicate that oxidation of the pellicle (e.g. oxidation of the capping layer) has occurred. An increased risk of pellicle failure may arise from the oxidation, and the pellicle assembly may therefore be replaced with a new pellicle assembly. Birefringence measurements—birefringence measurements, which may also be referred to as photoelasticity measurements, may be used to measure localized changes in the stress of the pellicle film. Birefringence may for example is measured by directing a radiation beam through the pellicle and measuring changes of the polarization of the radiation beam. Measurements of the birefringence of the pellicle may be used to find changes in the stress of the pellicle and/or localized stress concentrations. When stress changes or localized stress concentrations are seen which indicate an increased risk of pellicle failure, the pellicle assembly may be replaced with a new pellicle assembly. Fourier transform infra-red spectroscopy—infra-red radiation (e.g. over a range of wavelengths) is directed towards the pellicle and the absorption of that infra-red radiation is measured. This may be used to monitor for localized changes of infra-red absorption of the pellicle film. The technique can be used to monitor for localized changes of the emissivity of the pellicle. For example, a minimum emissivity value for the pellicle may be set as 0.3. If the emissivity (e.g. localized emissivity) is lower than 0.3 then this may indicate damage of the pellicle. The lower emissivity could cause a localized temperature increase of the pellicle during use in the lithographic apparatus which in turn gives rise to an increased risk of pellicle breakage. The pellicle assembly is therefore replaced with a new pellicle assembly. ‘Measurement of pellicle displacement due to pressure difference—this involves applying a pressure on one side of the pellicle which is different to the pressure on the other side of the pellicle. The pellicle will deflect towards the lower pressure side. The degree of deflection is dependent upon the stress of the pellicle, and a deflection which falls outside of predetermined threshold values may indicate an increased risk of pellicle failure. In one example, a maximum threshold deflection of 500 μm for a pressure difference of 2 Pascals may be set. If the deflection is larger than 500 μm then this indicates a significant risk of pellicle breakage (e.g. during pumpdown or venting), and the pellicle assembly is therefore replaced with a new pellicle assembly. In another example, if the deflection is less than 400 μm then this may indicate that the stress in the pellicle is significantly higher than the stress in the pellicle as originally fabricated (i.e. as attached to the pellicle frame but before use in the lithographic apparatus). A significant increase of the stress in the pellicle may mean an increased risk of pellicle breakage during use by the lithographic apparatus. The pellicle assembly is therefore replaced with a new pellicle assembly. Frame deformation measurements—this involves applying force to the pellicle frame to cause a deformation of the pellicle frame, and then monitoring wrinkles of the pellicle which occur during the pellicle frame deformation. The positions of wrinkles in the pellicle are indicative of the stress in the pellicle. An initial measurement of the positions of the wrinkles may be performed before the pellicle is used in order to provide a reference measurement. Following use, a change of position of the wrinkles compared with that seen in the reference measurement indicates a change in the stress of the pellicle. If a significant change of the stress of the pellicle is seen which is associated with an increased risk of pellicle breakage, then the pellicle assembly is replaced with a new pellicle assembly [0207-0211]. As mentioned further above, inspection of the pellicle after removal from the mask may be performed in parallel with inspection and/or cleaning of the mask [0212] Monitoring the pellicle, for example using one or more of the above techniques, allows damage of the pellicle to be identified early, and therefore allows the pellicle assembly to be replaced before failure of the pellicle occurs. If failure of the pellicle were to occur in the lithographic apparatus, e.g. during exposure of a substrate, then this could cause problematic contamination of the lithographic apparatus. This issue is avoided by monitoring for damage of the pellicle which is associated with an increased risk of pellicle failure, and replacing the pellicle as necessary when such damage is found. Inspection of the pellicle for contamination may be performed at the same time as inspecting for pellicle damage [0213-0214]
Kim et al. KR 101738887 (machine translation attached) teaches an apparatus for inspecting EUV pellicles including an EUV source, a mirror for directing the EUV toward the pellicle, a beam splitter which reflects a portion of the EUV light to a first detector (40), the pellicle (10), which can be shifted in the vertical (Z) direction as shown in the figure and a second detector which measures the light transmitted by the pellicle [0022-0028].
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Tanaka JP 2021015027 (machine translation attached) teaches an inspection process which can determine which surface of an EUV pellicle a defect or foreign matter is on (abstract). In the exposure process before the EUVL process, even if foreign matter adheres to the surface of the pellicle film, the image of the foreign matter is not projected on the wafer, so the foreign matter inspection on the pellicle film has not been regarded as important. However, in the EUVL process, when foreign matter adheres to the surface of the pellicle film, EUV light is absorbed by the foreign matter, so that there is a problem that an error occurs in the pattern projected on the wafer. Therefore, in the EUVL process, it is strongly desired to inspect and analyze defects such as foreign substances in the pellicle film (called EUV pellicle) used for the EUV mask [0002]./.
Next, as shown in step S18 of FIG. 2, the defect position is detected. Specifically, the processing unit 60 detects the position of a defect formed in the thin film 71 based on the luminance distribution of the converted spatial frequency and the time change of the displacement of the thin film 71. For example, the processing unit 60 compares the luminance distribution of the spatial frequency when the illumination light L3 focuses on the thin film 71 and when the defect is focused with the time change of the displacement of the thin film 71, so that the defect is formed in the thin film. It detects whether it is above or below 71. As shown in FIG. 12, the processing unit 60 acquires the luminance distribution of the spatial frequency when the defect is in focus, and then, as shown in FIG. 14, the luminance distribution of the spatial frequency when the thin film 71 is in focus. Is obtained. At that time, it is assumed that the processing unit 60 has acquired that the thin film 71 has been displaced in the + Z axis direction from the time change of the displacement of the thin film 71. In such a case, the processing unit 60 determines that the defect is above the thin film 71. That is, the processing unit 60 detects that a defect such as a foreign substance is on the surface side of the thin film 71 such as the EUV pellicle. On the other hand, as shown in FIG. 12, the processing unit 60 acquires the luminance distribution of the spatial frequency when the defect is in focus, and then, as shown in FIG. 14, the spatial frequency when the thin film 71 is in focus. It is assumed that the brightness distribution is acquired. At that time, it is assumed that the processing unit 60 has acquired that the thin film 71 has been displaced in the −Z axis direction from the time change of the displacement of the thin film 71. In such a case, the processing unit 60 determines that the defect is below the thin film 71. That is, the processing unit 60 detects that a defect such as a foreign substance is on the back surface side of the thin film 71 such as the EUV pellicle. Further, as shown in FIG. 14, the processing unit 60 acquires the luminance distribution of the spatial frequency when the thin film 71 is in focus, and then, as shown in FIG. 12, the spatial frequency when the defect is in focus. It is assumed that the brightness distribution is acquired. At that time, it is assumed that the processing unit 60 has acquired that the thin film 71 has been displaced in the + Z axis direction from the time change of the displacement of the thin film 71. In such a case, the processing unit 60 determines that the defect is below the thin film 71. That is, the processing unit 60 detects that a defect such as a foreign substance is on the back surface side of the thin film 71 such as the EUV pellicle. Further, as shown in FIG. 14, the processing unit 60 acquires the luminance distribution of the spatial frequency when the thin film 71 is in focus, and then, as shown in FIG. 12, the spatial frequency when the defect is in focus. It is assumed that the brightness distribution is acquired. At that time, it is assumed that the processing unit 60 has acquired that the thin film 71 has been displaced in the −Z axis direction from the time change of the displacement of the thin film 71. In such a case, the processing unit 60 determines that the defect is above the thin film 71. That is, the processing unit 60 detects that a defect such as a foreign substance is on the surface side of the thin film 71 such as the EUV pellicle. In this way, the inspection device 1 can determine whether the defect of the thin film 71 exists on the front surface or the back surface of the thin film 71 [0069-0075].
Brouns et al. 20180314150 exemplifies using EUV transmission of the pellicle attached to the mask and comparing a map of the image where if the difference in the pellicle is significant, the pellicle assembly is changed [0199], but does not exemplify this with a shift in the focusing or a determination of the number of internal particles, continuing use of the mask/pellicle in exposing wafers or replacement of the pellicle.
With respect to claims 1-7 and 15-18, it would have been obvious to modify the EUV transmission pellicle evaluation technique using the lithographic exposure apparatus of Brouns et al. 20180314150 to evaluate contamination from particles based upon these being described as contaminants at [0131] and the description of the inspection of the mask/pellicle assembly for contaminants in the lithographic apparatus at [0150,0159,0161] of Brouns et al. 20180314150
and using it to determine if the mask/pellicle assembly can be used or needs to be replaced as discussed at [0203] of Brouns et al. 20180314150 and to include a shifting of the relative positions of the focal plane and the pellicle as taught by Tanaka JP 2021015027 and Kim et al. KR 101738887 to allow the size and location of the particles to be determined as well as any tears/defects in the pellicle membrane as discussed in Tanaka JP 2021015027 and if no particles are detected continue using the mask pellicle in lithographic exposure processing, if the particles are detected only on the outside of the pellicle, removing the particles and continue using the mask pellicle in lithographic exposure processing and if particles are detected on the inside of the pellicle or defects in the pellicle are detected, removing the mask/pellicle from the exposure device, replacing the pellicle with a new (second) and using the new pellicle/mask in lithographic exposure processing as taught by Brouns et al. 20180314150 at [0163-0164,0195,0198-0199,0203,0214] with a reasonable expectation of being able to detect the location of any particles on the outer or interior surfaces of the mask/pellicle composite.
Claims 1-7 and 15-18 are rejected under 35 U.S.C. 103 as being unpatentable over Brouns et al. 20180314150, in view of Tanaka JP 2021015027 and Kim et al. KR 101738887, further in view of Badger et al. 6635390, Cullins 20210302827 and/or Van Der Muellen et al. WO 2016079052.
Badger et al. 6635390 teaches Accordingly, the lithographic process typically comprises using a thin transparent membrane referred to as a pellicle to shield or seal off the photomask surface from the surrounding environment. The pellicle membrane is offset from the photomask surface, typically by a thin-walled rectangular pellicle frame which is adhered to the reticle. The pellicle membrane and frame create an enclosed air space above the photomask which ideally is free of foreign particles. Particles which subsequently settle on the outer surface of the pellicle membrane do not affect the printing result because they are offset from the focal plane of the lithographic optics. In view of the importance of keeping the photomask particle-free, great efforts are undertaken to provide an environment for the reticles which is free of contaminants to the extent possible. Nevertheless, in spite of the precautions taken, even after the pellicle frame and pellicle membrane have been adhered to the reticle, foreign particles will be present on the photomask surface within the air space provided by the pellicle frame. Once the pellicle frame is assembled and adhered to the reticle, an inspection process may be performed in which optical equipment is used to look through the pellicle membrane at the surface of the reticle to detect particles. If particles are detected, the pellicle assembly must be removed, which may damage the reticle and cause additional foreign matter to be introduced (1/38-65)
Van Der Muellen et al. WO 2016079052 discloses that the useful lifetime of a pellicle 19 may be less than the useful lifetime of a patterning device MA. It may therefore be desirable to remove a pellicle assembly 16 from patterning device MA and replace the pellicle assembly with a new pellicle assembly so as to allow for continued use of the patterning device MA [000166]. In some embodiments the patterning device MA and/or the pellicle 19 may be inspected for particles and/or defects in the pellicle frame attachment apparatus 857 whilst the components are held in a vacuum. The patterning device MA and/or the pellicle 19 are therefore advantageously inspected under similar pressure conditions to those to which they are exposed during use in the lithographic apparatus LA. This is advantageous since any particles which may be deposited onto patterning device MA and/or the pellicle during pumping down to vacuum conditions may be detected in the pellicle frame attachment apparatus 857 [000163]. It may be desired to remove the pellicle assembly 16 from the patterning device MA (e.g. if contamination has been detected on the pellicle) [000217]
Cullins 20210302827 teaches that the photomask is removed from the lithography chamber. In the context of FIG. 1, the photomask 22 and pellicle 32 are removed from the interior space 12 of the lithography chamber 10 through the chamber door 18 by an automated transfer robot and/or by a person manually removing the photomask 22 and pellicle 32. A visual or automated inspection of the photomask 22 may be implemented to determine when the photomask 22 should to be removed for performance of subsequent operations (e.g., when particulates are present on the photomask 22), which may or may not require the removal of the pellicle 32 from being attached to the photomask 22. Additionally, a pre-determined number of performances of the lithography process of operation 104 may be performed and/or a pre-determined amount of time may pass to determine when the photomask 22 should to be removed for performance of subsequent operations [0038].
In addition to the basis above, the examiner cites Badger et al. 6635390 and Van Der Muellen et al. WO 2016079052 to support the obviousness of the process claimed. Noting that the Badger et al. 6635390 at (1/38-65) teaches that particles can be trapped in the interior volume of the pellicle after attachment and that this requires that the pellicle be removed and the mask cleaned and Van Der Muellen et al. WO 2016079052 establishes that the useful lifetime of the photomask is longer than that of the pellicle or the teaching that inspection for particles is routinely performed after a certain number of exposures or certain amount of time, so it is reasonably expected that at some time in the processes rendered obvious by the combination of Brouns et al. 20180314150, Tanaka JP 2021015027 and Kim et al. KR 101738887, the pellicle would be removed, the mask cleaned, a new(second) pellicle adhered to the mask and the result used in lithographic processing.
8. Claims 1-7 and 15-20 are rejected under 35 U.S.C. 103 as being unpatentable over Brouns et al. 20180314150, in view of Tanaka JP 2021015027 and Kim et al. KR 101738887, further in view of Kato EP 1536289 and Oouchi JP 2008198799.
Kato EP 1536289 teaches a method of measuring an optical aberration of an optical system comprising: (a) generating an optical wavefront;(b) passing the optical wavefront through the optical system (18);(c) passing the optical wavefront through a mask (20); and(d) analyzing the light that has passed through the optical system and the mask to derive a measure of the optical aberration of the optical system, characterized by: (e) analyzing the light that has passed through the mask to determine whether the mask is at least one of (i) misaligned relative to the optical wavefront and (ii) at least partially obstructed by a contaminant; and, if it is so determined,(f) taking remedial action (claim 12)
Oouchi JP 2008198799 (machine translation attached) discloses a projection optical system 150 has a function of projecting the mask pattern onto the wafer 160, and is a test optical system for the wavefront aberration measuring apparatus. The projection optical system 150 applied to EUV light is extremely sensitive to positional accuracy and thermal deformation, and it is necessary to measure wavefront aberration between exposures and adjust the mirror position based on the measurement results to provide feedback. There is. Further, impurities adhere to the multilayer mirror of the projection optical system 150 and cause a chemical change, so that a phase change due to a so-called contaminant also occurs. For this reason, it is necessary to measure the wavefront aberration of the projection optical system 150 due to the exposure wavelength on the exposure apparatus main body, but the exposure apparatus 100 is equipped with the wavefront aberration measuring apparatus described in the first and second embodiments, and this requirement is satisfied [0106].
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With respect to claims 1-7 and 15-20, it would have been obvious to modify the EUV transmission pellicle evaluation technique using the lithographic exposure apparatus of Brouns et al. 20180314150 to evaluate contamination from particles based upon these being described as contaminants at [0131] and the description of the inspection of the mask/pellicle assembly for contaminants in the lithographic apparatus at [0150,0159,0161] of Brouns et al. 20180314150
and using it to determine if the mask/pellicle assembly can be used or needs to be replaced as discussed at [0203] of Brouns et al. 20180314150, to include a shifting of the relative positions of the focal plane and the pellicle as taught by Tanaka JP 2021015027 and Kim et al. KR 101738887 to allow the size and location of the particles to be determined as well as any tears/defects in the pellicle membrane as discussed in Tanaka JP 2021015027 and the use a wavefront image detector (camera) in the lithographic apparatus as taught by Oouchi JP 2008198799 to determine the presence of the particles/contaminants as taught by Kato EP 1536289 and Oouchi JP 2008198799 and if no particles are detected continue using the mask pellicle in lithographic exposure processing, if the particles are detected only on the outside of the pellicle, removing the particles and continue using the mask pellicle in lithographic exposure processing and if particles are detected on the inside of the pellicle or defects in the pellicle are detected, removing the mask/pellicle from the exposure device, replacing the pellicle with a new (second) and using the new pellicle/mask in lithographic exposure processing as taught by Brouns et al. 20180314150 at [0163-0164,0195,0198-0199,0203,0214] with a reasonable expectation of being able to detect the location of any particles on the outer or interior surfaces of the mask/pellicle composite.
Claims 1-9,12,13 and 15-18 are rejected under 35 U.S.C. 103 as being unpatentable over Brouns et al. 20180314150, in view of Tanaka JP 2021015027 and Kim et al. KR 101738887, further in view of Yang et al. 20220357662 and Patra DE 102017221420
Yang et al. 20220357662 teaches with respect to figure 4A, that in some embodiments, pressure is exerted by actuator 351 on one or more facets of the mirrors (625A and/or 625B) to change the curvature and focal length of the one or more facets to adjust the width of the EUV radiation beam on the reticle (205) [0043]
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Patra DE 102017221420 (machine translation attached) teaches with respect to figures 3A and 3B, The 3A shows the field facet 202c in the position P2 , wherein a curvature of the reflection surface 203c was not changed and in particular not to the position P2 was adjusted. Like in the 3A includes the EUV light source 106A a plasma source 208 for generating the EUV radiations 108A and a collector 209 for bundling the EUV radiations 108A , The field facet 202c projects an image of the intermediate focus 201 with the picture light bunch 212 on the pupil facet 205d , The pupil facet surface 206d the pupil facet 205d however, does not exactly correspond to one imaging area 210 in which the image of the intermediate focus 201 is perfectly focused. Instead, the pupil facet surface is 206d in the 3A closer to the field facet 202c as the picture surface 210 so that the picture of the intermediate focus 201 with the picture light bunch 212 on the pupil facet 205d not focused. Between the pupil facet surface 206d and the picture surface 210 there is a gap d , This unfocused image is characterized in that one through the imaging light beam 212 irradiated area 211 by the in the 3A each two adjacent lines is limited, is large. This is because the curvature of the reflection surface 203c the field facet 202c was not optimized. The through the picture light bundle 212 irradiated area 211 is in the 3C shown. The 3C shows a plan view of the pupil facet surface 206d the pupil facet 205d which is substantially rectangular and one length L .sub.1 and a width B .sub.1 Has. The through the picture light bundle 212 Irradiated area of the pupil facet surface 206d that of the irradiated area 211 corresponds, is in the 3C hatched shown. Like in the 3C is the irradiated area 211 big: the irradiated area 211 covers almost the entire pupil facet surface 206d from. The 3B shows the field facet 202c in the position P2 after a change in the curvature of the reflection surface 203c , in particular after an optimization of the curvature of the reflection surface 203c the field facet 202c , In the 3B became the curvature of the reflection surface 203c changed so that they are the distance d between the pupil facet surface 206d and the picture surface 210 to reduce. In the 3B is the distance d null, so that the pupil facet surface 206d and the picture surface 210 lie one above the other. The picture of the intermediate focus 201 with the picture light bunch 212 on the pupil facet 205d is in the 3B perfectly focused and the irradiated area 211 is opposite the irradiated area 211 in the 3A significantly reduced [0077-0080].
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With respect to claims 1-9,12,13 and 15-18, it would have been obvious to modify the EUV transmission pellicle evaluation technique using the lithographic exposure apparatus of Brouns et al. 20180314150 to evaluate contamination from particles based upon these being described as contaminants at [0131] and the description of the inspection of the mask/pellicle assembly for contaminants in the lithographic apparatus at [0150,0159,0161] of Brouns et al. 20180314150 and using it to determine if the mask/pellicle assembly can be used or needs to be replaced as discussed at [0203] of Brouns et al. 20180314150 and to include a shifting of the relative positions of the focal plane and the pellicle as taught by Tanaka JP 2021015027 and Kim et al. KR 101738887 to allow the size and location of the particles to be determined as well as any tears/defects in the pellicle membrane as discussed in Tanaka JP 2021015027 using changes in the position/shape of the reflectors illuminating the EUV pellicle/mask composite to change the focal plane location to detect contaminants as is known in the art from Yang et al. 20220357662 at [0043] and Patra DE 102017221420 at [0077-0080] and if no particles are detected continue using the mask pellicle in lithographic exposure processing, if the particles are detected only on the outside of the pellicle, removing the particles and continue using the mask pellicle in lithographic exposure processing and if particles are detected on the inside of the pellicle or defects in the pellicle are detected, removing the mask/pellicle from the exposure device, replacing the pellicle with a new (second) and using the new pellicle/mask in lithographic exposure processing as taught by Brouns et al. 20180314150 at [0163-0164,0195,0198-0199,0203,0214] with a reasonable expectation of being able to detect the location of any particles on the outer or interior surfaces of the mask/pellicle composite.
Claims 1-9 and 12-18 are rejected under 35 U.S.C. 103 as being unpatentable over Brouns et al. 20180314150, in view of Tanaka JP 2021015027 and Kim et al. KR 101738887, further in view of Yang et al. 20220357662, Patra DE 102017221420 and Van Dijsseldonk et al. 20120147349.
Van Dijsseldonk et al. 20120147349 teaches One of the mirrors M1, M2 and M3 of the optical system 65, preferably mirror M3 which is the furthest downstream in the beam path may further be mounted so as to be rotatable with respect to the rest of the optical system 65 in order to be able to shift the location of the focal point. In an embodiment, the rotatable mirror, e.g. mirror M3, is adjusted during calibration and/or maintenance of the apparatus to set the focal point of the optical system to a predetermined point. In another embodiment, the rotatable mirror is adjustable dynamically during operation to ensure that the beam is incident on the target material. In this embodiment a sensor 81 senses the position of particles or droplets of target material 72. An actuator 82 drives the mirror M3 to adjust the position of the focal point to coincide with a particle or droplet of target material 72. The actuator 82 is controlled by a controller 83 which is responsive to the position sensed by the sensor 81 [0053].
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With respect to claims 1-9,12,13 and 15-18, it would have been obvious to modify the EUV transmission pellicle evaluation technique using the lithographic exposure apparatus of Brouns et al. 20180314150 to evaluate contamination from particles based upon these being described as contaminants at [0131] and the description of the inspection of the mask/pellicle assembly for contaminants in the lithographic apparatus at [0150,0159,0161] of Brouns et al. 20180314150 and using it to determine if the mask/pellicle assembly can be used or needs to be replaced as discussed at [0203] of Brouns et al. 20180314150 and to include a shifting of the relative positions of the focal plane and the pellicle as taught by Tanaka JP 2021015027 and Kim et al. KR 101738887 to allow the size and location of the particles to be determined as well as any tears/defects in the pellicle membrane as discussed in Tanaka JP 2021015027 using rotation of the reflector/mirror to adjust the focusing as taught by Van Dijsseldonk et al. 20120147349 noting that the use of changes in the position/shape of the reflectors illuminating the EUV pellicle/mask composite to change the focal plane location and detect contaminants as is known in the art from Yang et al. 20220357662 at [0043] and Patra DE 102017221420 at [0077-0080] and if no particles are detected continue using the mask pellicle in lithographic exposure processing, if the particles are detected only on the outside of the pellicle, removing the particles and continue using the mask pellicle in lithographic exposure processing and if particles are detected on the inside of the pellicle or defects in the pellicle are detected, removing the mask/pellicle from the exposure device, replacing the pellicle with a new (second) and using the new pellicle/mask in lithographic exposure processing as taught by Brouns et al. 20180314150 at [0163-0164,0195,0198-0199,0203,0214] with a reasonable expectation of being able to detect the location of any particles on the outer or interior surfaces of the mask/pellicle composite.
Claims 1-13 and 15-20 are rejected under 35 U.S.C. 103 as being unpatentable over Brouns et al. 20180314150, in view of Tanaka JP 2021015027, Kim et al. KR 101738887, Kato EP 1536289 and Oouchi JP 2008198799, further in view of Yang et al. 20220357662 and Patra DE 102017221420
With respect to claims 1-13 and 15-20, it would have been obvious to modify the EUV transmission pellicle evaluation technique using the lithographic exposure apparatus of Brouns et al. 20180314150 to evaluate contamination from particles based upon these being described as contaminants at [0131] and the description of the inspection of the mask/pellicle assembly for contaminants in the lithographic apparatus at [0150,0159,0161] of Brouns et al. 20180314150
and using it to determine if the mask/pellicle assembly can be used or needs to be replaced as discussed at [0203] of Brouns et al. 20180314150, to include a shifting of the relative positions of the focal plane and the pellicle as taught by Tanaka JP 2021015027 and Kim et al. KR 101738887 to allow the size and location of the particles to be determined as well as any tears/defects in the pellicle membrane as discussed in Tanaka JP 2021015027 and the use a wavefront image detector (camera) in the lithographic apparatus as taught by Oouchi JP 2008198799 to determine the presence of the particles/contaminants as taught by Kato EP 1536289 and Oouchi JP 200819879 using changes in the position/shape of the reflectors illuminating the EUV pellicle/mask composite to change the focal plane location to detect contaminants as is known in the art from Yang et al. 20220357662 at [0043] and Patra DE 102017221420 at [0077-0080] and if no particles are detected continue using the mask pellicle in lithographic exposure processing, if the particles are detected only on the outside of the pellicle, removing the particles and continue using the mask pellicle in lithographic exposure processing and if particles are detected on the inside of the pellicle or defects in the pellicle are detected, removing the mask/pellicle from the exposure device, replacing the pellicle with a new (second) and using the new pellicle/mask in lithographic exposure processing as taught by Brouns et al. 20180314150 at [0163-0164,0195,0198-0199,0203,0214] with a reasonable expectation of being able to detect the location of any particles on the outer or interior surfaces of the mask/pellicle composite.
Claims 1-20 are rejected under 35 U.S.C. 103 as being unpatentable over Brouns et al. 20180314150, in view of Tanaka JP 2021015027, Kim et al. KR 101738887, Kato EP 1536289 and Oouchi JP 2008198799, further in view of Yang et al. 20220357662, Patra DE 102017221420 and Van Dijsseldonk et al. 20120147349
With respect to claims 1-20, it would have been obvious to modify the EUV transmission pellicle evaluation technique using the lithographic exposure apparatus of Brouns et al. 20180314150 to evaluate contamination from particles based upon these being described as contaminants at [0131] and the description of the inspection of the mask/pellicle assembly for contaminants in the lithographic apparatus at [0150,0159,0161] of Brouns et al. 20180314150
and using it to determine if the mask/pellicle assembly can be used or needs to be replaced as discussed at [0203] of Brouns et al. 20180314150, to include a shifting of the relative positions of the focal plane and the pellicle as taught by Tanaka JP 2021015027 and Kim et al. KR 101738887 to allow the size and location of the particles to be determined as well as any tears/defects in the pellicle membrane as discussed in Tanaka JP 2021015027 and the use a wavefront image detector (camera) in the lithographic apparatus as taught by Oouchi JP 2008198799 to determine the presence of the particles/contaminants as taught by Kato EP 1536289 and Oouchi JP 200819879 using rotation of the reflector/mirror to adjust the focusing as taught by Van Dijsseldonk et al. 20120147349 noting that the use of changes in the position/shape of the reflectors illuminating the EUV pellicle/mask composite to change the focal plane location and detect contaminants as is known in the art from Yang et al. 20220357662 at [0043] and Patra DE 102017221420 at [0077-0080] and if no particles are detected continue using the mask pellicle in lithographic exposure processing, if the particles are detected only on the outside of the pellicle, removing the particles and continue using the mask pellicle in lithographic exposure processing and if particles are detected on the inside of the pellicle or defects in the pellicle are detected, removing the mask/pellicle from the exposure device, replacing the pellicle with a new (second) and using the new pellicle/mask in lithographic exposure processing as taught by Brouns et al. 20180314150 at [0163-0164,0195,0198-0199,0203,0214] with a reasonable expectation of being able to detect the location of any particles on the outer or interior surfaces of the mask/pellicle composite.
The prior art made of record and not relied upon is considered pertinent to applicant's disclosure.
Hayano et al. 4889998 FIGS. 1 and 2 show the condition or appearance of illumination and scattered light from foreign particles when a light-permeable pellicle 1 to upper and lower surfaces of which foreign particles 2 and 3 are stuck is illuminated from different directions. Particularly, FIG. 1 shows illumination light 4 and scattered light from the foreign particles 2 and 3 when the pellicle 1 is illuminated from a direction that forms a relatively large angle with respect to the plane of the pellicle (referred to as "epiillumination" hereinafter). On the other hand, FIG. 2 shows illumination light 5 and scattered light from the foreign particles when the pellicle 1 is illuminated from a direction that forms a relatively small angle with respect to the plane of the pellicle (referred to as "oblique illumination" hereinafter). Firstly, the quantity of scattered light emitted from the foreign particles received in a given direction, for example direction A shown in FIGS. 1 and 2 will be comparatively explained with respect to the epi-illumination and oblique illumination. The quantity of scattered light emitted from the foreign particle 2 stuck to the upper surface of the pellicle 1 under the epi-illumination is substantially the same as that under the oblique illumination, if the quantity of the light of the epi-illumination is substantially the same as that of the oblique illumination. On the other hand, with respect to the foreign particle 3 stuck to the lower surface of the pellicle 1, the quantity of the scattered light from the foreign particle under the oblique illumination is less than that under the epi-illumination, due to the fact that under the oblique illumination, since the illumination light 5 is reflected substantially completely on the upper surface of the pellicle 1, the quantity of light reaching the foreign particle 3 is less than that under the epi-illumination where a large amount of the illumination light passes through the pellicle 1. Accordingly, it is possible to discriminate whether the foreign particle is stuck to the upper surface of the pellicle or the lower surface thereof, by illuminating the pellicle surface from two different directions and by comparing the quantity of the scattered light from the foreign particle obtained by such illumination from two directions. Secondly, the quantity of scattered light emitted from the foreign particles received in two different directions, for example directions A and B shown in FIGS. 1 and 2 when the pellicle is illuminated from a given direction will be explained With respect to the foreign particle 2 stuck to the upper surface of the pellicle 1, the quantity of the scattered light from the foreign particle 2 received in the direction A is substantially the same as that received in the direction B. On the other hand, with respect to the foreign particle 3 stuck to the lower surface of the pellicle 1, the quantity of the scattered light received in the direction B is less than that received in the direction A, due to the fact that the scattered light directed from the foreign particle 3 to the direction B is almost reflected on the lower surface of the pellicle 1. Accordingly, it is possible to discriminate whether the foreign particle is stuck to the upper surface of the pellicle or the lower surface thereof, by illuminating the pellicle from a given direction, by receiving the scattered light from the foreign particle in two different directions and by comparing the quantity of the received light in said two directions. Further, as shown in FIG. 2, when an incident angle of the illumination light 5 in the oblique illumination is so selected that the illumination light 5 is totally reflected on the pellicle surface, if there is no foreign particle stuck to the upper surface of the pellicle, since the oblique illumination light 5 is totally reflected on the upper surface of the pellicle and the scattered light from the foreign particle 3 stuck to the lower surface of the pellicle is also totally reflected on said lower surface, the difference in the quantity of light between the scattered light directed to the direction A in FIG. 1 and that directed to the direction B can be more precisely clarified, which is desirable for the detection of the foreign particles (4/17-5/29)
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Obara JP H10267862 (machine translation attached) illustrates in figure 4, various positions that contaminants (81,84,85,86,87,88) can be between the pellicle membrane (72b, 72a) and the mask (71) and mask pattern (74).
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Recently, in order to prevent foreign matter from adhering, a light-transmitting thin film (hereinafter, referred to as a pellicle) is mounted on a surface of a reticle via a support frame. Even a reticle covered with a pellicle as described above may have foreign matter attached to the surface of the reticle. Therefore, the reticle on which the pellicle is mounted is also inspected for the presence of foreign matter. By the way, even if the foreign matter detected by the scattered light in the foreign matter adheres, there is a case where no defect actually occurs in the circuit pattern transferred to the wafer or a case where it is an acceptable defect. . In such a case, the adhesion of the foreign matter does not hinder the use of the reticle. For this reason, a person performs a visual observation using a microscope or the like on a portion where a foreign substance is detected in the foreign substance inspection using the scattered light, and determines whether or not the reticle can be used [0004-0005]. The reticle determined to be unusable in the above visual observation is subjected to pellicle removal and cleaning, and is returned to the step of inspecting the reticle for foreign matter before mounting the pellicle [0012] When the difference between the position indicated by the searched foreign object information and the position indicated by the foreign object information received this time is within a predetermined range, it is determined that the foreign object at the position does not prevent the use of the reticle. A featured foreign matter inspection device is provided. According to a second aspect of the present invention, in a foreign matter inspection method for inspecting foreign matter in a reticle on which a pattern is formed and a reticle with a pellicle assembled by mounting the pellicle on the reticle, the foreign matter before assembly is provided. A first foreign matter inspection step of performing a foreign matter inspection on the pellicle; and a second foreign matter inspection step of performing a foreign matter inspection on the reticle of the reticle with the pellicle after assembly. Detects foreign matter adhering, when foreign matter is detected, inspects whether the position where the foreign matter is detected on the reticle is usable, and when the reticle is usable, identification information for identifying this pellicle and The position at which the foreign matter is detected is stored in association with the reticle-attached reticle in the second foreign matter inspection step. Foreign matter is detected. When the foreign matter is detected, the foreign matter information stored in the foreign matter information corresponding to the identification information of the reticle included in the reticle with the pellicle is searched. When the position and the position of the foreign matter acquired this time are within a predetermined range, a foreign matter inspection method is provided in which it is determined that the use of the reticle with a pellicle is not hindered by the foreign matter [0017-10018].
Choi et al. 20230194845 teaches adhering a pellicle to an EUV photomask to prevent or reduce the impurities or foreign material from adhering to the photomask surface [0003]. The mask is used as an inspection target for detecting defects in the pellicle [0024].
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Two different wavelengths of light with different polarization are used in the evaluation of the pellicle. The two different lights (L1 and L2) is focused on the upper surface of the EUV photomask, the upper surface of the pellicle membrane (430) or the lower surface of the pellicle membrane. When the focus is on the mask surface foreign substances are not easily detected. When the focus is near the upper surface or lower surface of the pellicle, defects or foreign material/particles are more easily detected. The position of the focus in the vertical/Z direction is change during the inspection. The inspection system may be a confocal optical system. The vertical stage is used to control the focal plane of the lens relative to the mask and pellicle membrane. The shapes of particles and location of particles on the mask is determined when the output of the detectors (140) is maximized [0035-0039].
The data acquisition system 190 may collect image signals output through the light detectors 140. The image processing unit 195 may acquire an image of the mask structure MS by synthesizing the signals received from the data acquisition system 190. The image may be or may include an image of the mask structure MS, and therefore, the presence and/or absence of at least one defect within the mask structure MS, and/or the size and/or the morphology of the defect may be analyzed. The image processing unit 195 may be or may include, for example, a computing system including a workstation, and may be connected to at least some other components of the photomask inspection apparatus 1000, e.g. through a wired and/or a wireless connection. According to the EUV photomask inspection apparatus 1000 of some example embodiments, visible light from the light sources 110 may be transmitted through the pellicle 430 to perform inspection, such that not only the surface of the mask structure MS but also foreign substances inside the mask structure may be inspected, without performing the inspection multiple times. Compared to the case of inspection using EUV light, example embodiments may be advantageous in terms of prices, such that mass productivity may be improved. Alternatively or additionally, by applying the confocal method while using visible light, the scattering of light by the pellicle 430 may be suppressed to secure detection accuracy [0043-0044]. For the comparative example, effective resolution is illustrated when the confocal optical system as illustrated in FIG. 1 and the hybrid light detector as illustrated in FIG. 2 are not used. As illustrated in FIG. 6A, the comparative example has a resolution of about 1 μm (1 micron), whereas the EUV photomask inspection apparatus of the example has a resolution of about 50 nm. Accordingly, a result of about 20 times improvement in resolution is obtained [0063]. FIGS. 7A to 7C are diagrams illustrating an image analysis method by an EUV photomask inspection apparatus according to some example embodiments. FIGS. 7A to 7C illustrate images corresponding to an example embodiment of an inspection method by image comparison performed by the image processing unit 195 of the EUV photomask inspection apparatus 1000 of FIG. 1. FIG. 7A illustrates a reference image for defect analysis as an example, FIG. 7B illustrates an analysis image obtained by analysis as an example, and FIG. 7C illustrates a differential image corresponding to a difference between the reference image and the analysis image as an example. The reference image may correspond to, for example, an image of the EUV photomask 410 before the pellicle 430 is attached. The analysis image may be an image of the mask structure MS obtained by inspection of the EUV photomask inspection apparatus 1000. The differential image may be extracted by analyzing the difference between the reference image and the analysis image, and therefore, for example, the analysis of a defect such as generation of a foreign material due to attachment of the pellicle 430 may be facilitated [0066-0068]
Mitome JP H1183752 (machine translation attached) discloses that if the size of the foreign matter is too large, the printed light beam is blocked, and the illuminance becomes uneven, which causes a reduction in resolution. FIG. 6 is an explanatory diagram of illuminance unevenness generated by a foreign matter. This concept is based on the calculation of the ratio of the area of the luminous flux emitted by the foreign substance at the defocused position to the total luminous flux in the illuminating luminous flux contributing to one point image formation as uneven illuminance [0006]. FIG. 7 is a graph showing the relationship between the particle size of the foreign matter and the illuminance unevenness generated based on this principle for the blank surface and the pellicle surface. In the case of a stepper having an NA of the projection lens of 0.54 to 0.6 and a resolving power of 0.4 to 0.45 μm, the illuminance unevenness due to foreign matter is empirically set to 0. It must be kept below 1%. For this reason, the resolution of foreign matter detection required by the surface condition inspection device on the blank surface is 15 to about 20 μm, the focus is on detecting foreign matter at a high speed and accuracy [0007]. In order to achieve the object, according to the present invention, information of a foreign substance signal obtained when a reticle in a state confirmed to be usable by test exposure is inspected by a surface state inspection apparatus is referred to as a reference state. The method is characterized in that a foreign substance signal obtained by the surface condition inspection apparatus is processed using the information. In the present invention, when a foreign matter which may be transferred is confirmed by inspecting the surface condition of the reticle, first, a position where the foreign matter is observed and a position where the scattered light of the foreign matter is photoelectrically converted. Store the output as information. Then, perform a test exposure to confirm that the foreign matter has not been transferred, If the reticle can be used, it is characterized by a signal processing for displaying only the increased number of foreign substances as compared with the stored foreign substance inspection information when the next foreign substance inspection is performed. By this processing, it is possible to detect only the foreign matter attached after the inspection when it is determined that the foreign matter can be used. In another process of the present invention, when a foreign matter which may be transferred is confirmed by inspecting the surface condition of the reticle, first, a position at which the foreign matter is observed and a scattered light of the foreign matter are converted into photoelectric. The converted output is stored as information. Next, test exposure is performed to confirm that the foreign matter has not been transferred. If the reticle is usable, As there is a difference between the foreign particles actually attached and the standard particles, It is characterized in that a reference value relating to the detection sensitivity of presence / absence of a foreign substance is changed in comparison with information stored at the time of foreign substance inspection. Conversely, some foreign matter has a greater effect on exposure than is set by standard particles. In such a case as well, in the procedure according to the present invention, when the surface state of the reticle is inspected and a foreign substance that may be transferred is confirmed, first, the position where the foreign substance is observed and the scattered light of the foreign substance are converted into photoelectric. The converted output is stored as information. Next, a test exposure is performed to confirm and transfer the transfer result of the foreign matter. Some foreign matter can be identified by its cause, and statistical processing on the output characteristics of the foreign matter can be performed from such special circumstances. That is, the difference between the transfer confirmation result and the estimation result from the standard particle is compared with data stored in the past, and the reference value relating to the detection sensitivity for the presence or absence of foreign matter is changed [0018-0023]. The measuring process uses a scattering technique disclosed with respect to figure 1, where the scattered light is imaged via lenses (7a,7b) onto line sensors (8a,bb). FIG. 1 is a schematic view of a surface condition inspection apparatus according to a first embodiment of the present invention. FIG. 1A shows the basic configuration of the detection optical system, and FIG. 1B shows the appearance and operation. In FIG. 1, reference numeral 1 denotes a reticle to be inspected, and 2 denotes a pellicle dust-proof frame attached to a pattern surface of the reticle 1. The laser light emitted from the semiconductor laser 3 is split by the half mirror 4 into two light beams having the same intensity, Light is applied to each of the blank surface 1a and the pellicle surface, which are the reticle back surfaces. In the figure, the illuminated area of the blank surface 1a is shown as 9. For simplicity of explanation, an example will be described below in which a foreign substance is inspected on the blank surface 1a. When a foreign substance 10 exists on the illumination area 9, the foreign substance 10 generates scattered light. The scattered light is imaged on the line sensor 8a by the imaging lens 7a for receiving scattered light arranged along the slit-shaped illumination area 9. In this embodiment, an array lens such as a gradient index lens array is used as the scattered light receiving lens 7a, but an imaging lens or a Fourier transform lens like a normal camera lens can also be used [0023-0024].
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Vladmirsky et al. 20100045955 discloses that dust or extraneous particulate matter appearing on the surface of the reticle can adversely affect the resulting product. Any particulate matter that deposits on the reticle before or during a lithographic process is likely to distort features in the pattern being projected onto a substrate. Therefore, the smaller the feature size, the smaller the size of particles that it is critical to eliminate from the reticle. A pellicle is often used with a reticle. A pellicle is a thin transparent layer that may be stretched over a frame above the surface of a reticle. Pellicles are used to block particles from reaching the patterned side of a reticle surface. Any particles on the pellicle surface are out of the focal plane and should not form an image on the wafer being exposed. However, it is still preferable to keep the pellicle surfaces as particle-free as possible [0006-0007]. Currently used high throughput lithography tools employ rapid in-situ reticle inspection devices to detect particulate contamination. Requirements of speed and a high signal-to-noise ratio have led to utilization of a probe imaging technique, a type of scatterometry, for this purpose. This technique is based on collecting scattered light from contamination and dust particles that have been illuminated in a reasonably small spot on the reticle surface. A reasonably sized spot (e.g., approximately 50 .mu.m to 300 .mu.m) is rastered, or scanned, over a test surface, collecting information from one spot at a time. For a 150 mm by 120 mm surface, this corresponds to an approximately 9 Mpixel image. The probe beam technique is demonstrated in FIGS. 1A-1C, 2, and 3. FIG. 1A depicts a portion 102 of an object, such as a reticle or pellicle. Probe beam spots 104 are shown, with arrow 106 showing the scan direction of a probe beam. A particle 108 is shown on one of probe beam spots 104 [0009] In an embodiment, illumination source or sources 456 may illuminate reticle surface 421 at an oblique angle 470 (e.g., at forty-five degrees or less) so that specular reflection can be prevented from reaching optical system 462 and sensor 464 (in order to avoid optical cross-talk and ghost imaging). In an alternative embodiment, sensor 464 can be placed so as to "look" at reticle surface 421 at an oblique angle, while illumination source 456 can provide normal light. The full field image of reticle surface 421 can be analyzed for particles or other abnormalities, such as particles 476 shown in FIG. 4 [0047]
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Shih et al. 20200057383 teaches a method of detecting status of a pellicle in an extreme ultraviolet (EUV) system that includes transporting a reticle for exposure to the extreme ultraviolet (EUV) radiation in an extreme ultraviolet (EUV) lithography system. The reticle includes a pellicle installed thereon. A presence of particles in the EUV lithography system is detected using a first sensor of a plurality of sensors installed in the EUV lithography system. In the presence of particles, the first sensor is activated. A second sensor of the plurality of sensor is activated in response to activating the first sensor. In an embodiment, the first sensor includes a particle counter, and the reticle and pellicle are removed from the EUV lithography system when a number of particles detected by the first sensor is greater than a threshold value. The damaged pellicle is replaced. In an embodiment, the EUV lithography system includes a plurality of stages each providing a different functionality of the EUV lithography system and the second sensor located in the same stage as the first sensor. In an embodiment, the EUV lithography system includes a plurality of stages each providing a different functionality of the EUV lithography system, the second sensor is located in a different stage from the first sensor. In an embodiment, a third sensor of the plurality of sensors is activated. The first, second, third sensors are activated sequentially. In an embodiment, the plurality of sensors includes one of an acoustic wave sensor and a microphone [0068]. The particle detector uses an acoustic wave detector [0067] or reflection of a scanned laser beam shown in figure 3 [0050].
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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.
Examiner interviews are available via telephone, in-person, and video conferencing using a USPTO supplied web-based collaboration tool. To schedule an interview, applicant is encouraged to use the USPTO Automated Interview Request (AIR) at http://www.uspto.gov/interviewpractice.
If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Mark F Huff can be reached at 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 February 4, 2026