A class of tin-oxygen metal clusters coordinated with dialkyl and organic cyclic carboxylic acids, their synthesis and applications

Abstract

This invention discloses a class of tin-oxygen metal clusters coordinated with dialkyl and organic cyclic carboxylic acids, their synthesis, and applications. These clusters exhibit higher reactivity due to the presence of more Sn atoms and more Sn-C bond reaction sites. The tin-oxygen metal clusters have the structure of general formula I.

Description

Technical Field

[0001] This invention relates to the field of fine chemicals, and more particularly to a class of tin-oxygen metal clusters coordinated with dialkyl and organic cyclic carboxylic acids, and their synthesis and application. Background Technology

[0002] Photolithography is a crucial process in semiconductor chip manufacturing, determining the final performance of the chip. During exposure, light passes through a patterned mask and illuminates a silicon wafer coated with photoresist, triggering a photolithographic reaction and solubility conversion. If the solubility decreases in the exposed area, it is a negative photoresist; conversely, if the solubility increases, it is a positive photoresist. This is followed by post-exposure baking (PEB) and development, which exposes the pattern from the mask onto the photoresist film. After etching, the photoresist film is removed, transferring the pattern from the mask onto the silicon wafer.

[0003] With the rapid development of IC feature sizes towards submicron and deep submicron, existing lithography machines and photoresists are no longer able to meet the requirements of new lithography processes. The exposure wavelengths of lithography machines are also evolving from ultraviolet g-line (436nm) to i-line (365nm) to 248nm to 193nm to extreme ultraviolet (EUV). EUV lithography technology, which uses extreme ultraviolet light with a wavelength of 10-14 nanometers as a light source, has become the mainstream trend in photoresist development. Future development of resolution nodes below 5 nm necessitates the urgent development of 13.5 nm extreme ultraviolet (EUV) lithography technology.

[0004] Because extreme ultraviolet (EUV) light has high single photon energy, its photon density is only about 1 / 14 of that of 193nm at the same exposure level. This leads to random effects. Furthermore, EUV light has a small absorption cross-section for elements such as C, H, and N, making it almost impossible to undergo efficient photolithography reactions. This further enhances the random effects, which can cause unnecessary contact defects or rough patterns in the chip, resulting in insufficient patterning resolution of the photoresist.

[0005] To improve resolution and linewidth roughness, the size of the photoresist and the migration of functional groups during exposure need to be considered. Without changing the size of the lithographic pattern, a thinner photoresist and a larger ratio of photoresist thickness to pattern feature size can cause the pattern to collapse during development due to the surface tension of the developer, resulting in poor etching resistance. Summary of the Invention

[0006] To overcome the shortcomings of existing EUV photoresists, such as insufficient patterning resolution and poor etching resistance, a method for synthesizing and applying a class of tin-oxygen clusters coordinated by alkyl and organic cyclic carboxylic acids with low dosage, high patterning resolution, and strong etching resistance is provided.

[0007] To achieve the above objectives, the technical solution of the present invention is: a type of tin-oxygen metal cluster coordinated with dialkyl and organic cyclic carboxylic acids, wherein the tin-oxygen metal cluster has the structure of general formula I.

[0008] In general formula I, R' is selected from alkyl groups having 1-18 carbons or alkenyl groups having 2-18 carbons; R'' is selected from cycloalkyl groups having 3-20 carbons, heterocycloalkyl groups having 3-20 carbons, cycloalkenyl groups having 3-20 carbons, or aromatic groups having 6-20 carbons, wherein one hydrogen is substituted or unsubstituted by a halogen, nitro, sulfonic acid group, alkyl group having 1-10 carbons.

[0009] Furthermore, R' is selected from alkyl groups having 1-8 carbons or alkenyl groups having 1-8 carbons; R'' is selected from cycloalkyl groups having 3-20 carbons or cycloalkenyl groups having 3-20 carbons.

[0010] A method for synthesizing a class of tin-oxygen metal clusters coordinated with dialkyl and organic cyclic carboxylic acids includes: reacting tin oxide S-1 with R' substituents and organic carboxylic acid S-2 with R'' substituents in an organic solvent at a molar ratio of 1:1-10 under inert gas protection, at a reaction temperature of 70-120℃ for 8 hours; after the reaction, cooling, vacuum evaporation, and drying overnight to obtain a residue; dissolving the residue in toluene, cooling to room temperature, and precipitating colorless crystals, wherein the colorless crystals are tin-oxygen metal clusters S-3; The reaction formula is as follows: .

[0011] Furthermore, the mass ratio of the mixture of tin oxide with R' substituent modification and organic carboxylic acid with R'' substituent modification to the organic solvent is 1 g: 1-5 mL.

[0012] Furthermore, the specific method for dissolving the residue with toluene is as follows: add 2-3 mL of toluene to the residue and heat to 90°C, stirring until the residue is completely dissolved.

[0013] Application of a class of dialkyl and organic cyclic carboxylic acid coordinated tin oxide metal clusters in extreme ultraviolet lithography and electron beam lithography, wherein the tin oxide metal clusters are used as photosensitizers and resins in photoresist formulations.

[0014] Furthermore, the photoresist is prepared by adding chloroform to a tin-oxygen metal cluster, ultrasonicating for 20 minutes, and then filtering to obtain a photoresist solution.

[0015] Furthermore, the tin oxide metal clusters serve as photosensitizers and resins in the electron beam photoresist formulation, enabling the patterning of 100 nm linewidth lines in electron beam lithography.

[0016] Furthermore, the tin-oxygen metal clusters, as photosensitizers and resins in extreme ultraviolet (EUV) photoresist formulations, can pattern 50 nm linewidth and 100 nm periodic lines during EUV lithography exposure.

[0017] In summary, the present invention has the following beneficial effects: 1. The tin-oxygen clusters coordinated with dialkyl and cyclic organic carboxylic acids described in this application have higher reactivity due to the presence of more Sn atoms and Sn-C bond reaction sites. Compared with ordinary tin-oxygen clusters, they have more Sn-C bond reaction sites. During exposure, the Sn-C bonds undergo homolytic cleavage under irradiation to generate alkyl radicals. The generated alkyl radicals will initiate a series of reactions, causing a change in solubility. Compared with monocoordinated tin-oxygen clusters, they have more reaction sites, resulting in higher photosensitivity and a lower dose required for exposure.

[0018] 2. The tin-oxygen clusters coordinated with dialkyl and cyclic organic carboxylic acids described in this invention have excellent periodic line patterning capabilities: During electron beam lithography (EBL) exposure, the movement of alkyl free radicals generated by the breaking of Sn-C bonds in the thin film determines the patterning capability of the photoresist. Compared with ordinary tin-oxygen clusters, the Sn-C bond energy of the clusters in this invention is large, the generated free radicals are unstable, and their existence time in the thin film is short, so their migration distance in the thin film is short, which is beneficial for completing the patterning of finer lines. 3. The cyclic carboxylic acid groups contained in the dialkyl and cyclic organic carboxylic acid coordinated tin oxide clusters of the present invention have a high C / H ratio, resulting in high etching resistance. Furthermore, extreme ultraviolet (EUV) lithography has better penetration of this cyclic alkane structure compared to aromatic compounds, without affecting the absorption of EUV light by Sn. Simultaneously, it possesses active reactive sites that can connect with Sn atoms to complete the polymerization reaction, becoming part of the polymer backbone and aiding in the solubility transformation. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 The image shows the X-ray structure of compound 1 prepared in Example 1 of this invention. Figure 2 The 1H NMR spectrum of compound 2 prepared in Example 2 of this invention; Figure 3 The 1H NMR spectrum of compound 3 prepared in Example 3 of this invention; Figure 4 The 1H NMR spectrum of compound 4 prepared in Example 4 of this invention; Figure 5 The 1H NMR spectrum of compound 5 prepared in Example 5 of this invention; Figure 6 The 1H NMR spectrum of compound 6 prepared in Example 6 of this invention; Figure 7 The contrast curves of compounds 1-6 prepared in Examples 1-6 of this invention under EBL are shown. Figure 8 This is a schematic SEM image of the film prepared using compound 1 with periodic line patterns under EBL. Figure 9 This is a schematic SEM image of the film prepared using compound 2 with periodic line patterns under EBL. Figure 10 This is a schematic SEM image of the periodically patterned lines of the thin film prepared using compound 3 under EBL. Figure 11 This is a schematic SEM image of the periodic lines formed by EUV exposure on a thin film prepared using compound 1. Figure 12 This is a schematic SEM image of the periodic lines formed by EUV exposure on a thin film prepared using compound 2. Figure 13 This is a schematic SEM image of the periodic lines formed by EUV exposure on a thin film prepared using compound 3. Figure 14 A schematic diagram of AFM showing the effect of deep silicon etching and RIE etching on the thickness change of the silicon substrate after etching; Figure 15 A schematic diagram of AFM of the thin films prepared using compounds 1 and 2 before and after deep silicon etching; Figure 16 This is a schematic diagram of the AFM of the films prepared using compounds 1 and 2 before and after RIE etching. Detailed Implementation

[0021] The present invention will now be described in further detail. Unless otherwise stated, the terms used herein have the following meanings. The term "halogen" as used in this article includes fluorine, chlorine, bromine, and iodine. The term "alkyl" as used in this invention includes straight-chain alkyl and branched-chain alkyl. X is used in this article - This refers to negative ions, which can be any suitable negative ion, including inorganic and organic negative ions. Examples include, but are not limited to, halide ions and OH- ions. - HCOO - CH3COO - CF3COO - or OTs - .

[0022] The instruments and equipment used in the embodiments are as follows: EBL experiments were conducted using the eLINE Plus exposure system from Ratih GmbH in Germany.

[0023] AFM results were obtained using the Dimension Icon device from Bruker, Inc., USA.

[0024] SEM results were obtained using the Hitachi SU5000 electron microscope system from Japan.

[0025] Etching resistance tests were performed using SPTS Technologies' OMEGA-ICP and Oxford Instruments' RIE-180, respectively.

[0026] Mercury was used for crystal parameter analysis.

[0027] Example Example 1 1.00 g of dimethyltin oxide, 1.05 g of 1-adamantane carboxylic acid, and 150 mL of toluene were added to a 250 mL round-bottom flask equipped with a Dean-Starck apparatus and a condenser. The mixture was refluxed under nitrogen protection for 10 h until completely dissolved. After the reaction, the mixture was cooled to room temperature, and the solution was evaporated under reduced pressure using a rotary evaporator. The solution was then dried overnight at 37 °C in a vacuum drying oven. The residue was added to 2-3 mL of toluene and heated to 90 °C until completely dissolved. The mixture was then slowly cooled to room temperature, and colorless crystals were obtained after 3 days at room temperature. The colorless crystals obtained in this example were taken as compound 1, and their structural formula is shown below. The crystal parameters are shown in Table 1. The yield of the crystalline product prepared in this example was 90%, and its X-ray structure was analyzed as follows. Figure 1 As shown, by Figure 1 It can be seen that the colorless crystals prepared in this embodiment have P - 1. Structure.

[0028]

[0029] Table 1 Crystal parameters of Example 1

[0030] Example 2 1.50 g of dibutyltin oxide, 1.05 g of 1-adamantane carboxylic acid, and 150 mL of toluene were added to a 250 mL round-bottom flask equipped with a Dean-Starck apparatus and a condenser. The mixture was refluxed under nitrogen protection for 10 h until completely dissolved. After the reaction, the mixture was cooled to room temperature, and the solution was evaporated under reduced pressure using a rotary evaporator. The solution was then dried overnight at 37 °C in a vacuum drying oven. The residue was added to 2-3 mL of toluene and heated to 90 °C until completely dissolved. The mixture was then slowly cooled to room temperature, and colorless crystals were obtained after 3 days at room temperature. The colorless crystals obtained in this example were taken as compound 2, and their structural formula is shown below. The yield of the crystalline product prepared in this example was 91%. 1 H NMR such as Figure 2 As shown.

[0031]

[0032] Example 3 1.32 g of diallyl tin oxide, 0.75 g of cyclohexanecarboxylic acid, and 150 mL of toluene were added to a 250 mL round-bottom flask equipped with a Dean-Starck apparatus and a condenser. The mixture was refluxed under nitrogen protection for 10 h until completely dissolved. After the reaction, the mixture was cooled to room temperature, and the solution was evaporated under reduced pressure using a rotary evaporator. The solution was then dried overnight at 37 °C in a vacuum drying oven. The residue was added to 2-3 mL of toluene and heated to 90 °C until completely dissolved. The mixture was then slowly cooled to room temperature, and colorless crystals were obtained after 3 days at room temperature. The colorless crystals obtained in this example were taken as compound 3, and their structural formula is shown below. The yield of the crystalline product prepared in this example was tested to be 95%. 1 H NMR such as Figure 3 As shown.

[0033]

[0034] Example 4 1.50 g of dibutyltin oxide, 0.75 g of cyclohexanecarboxylic acid, and 150 mL of toluene were added to a 250 mL round-bottom flask equipped with a Dean-Starck apparatus and a condenser. The mixture was refluxed under nitrogen protection for 10 h until completely dissolved. After the reaction, the mixture was cooled to room temperature, and the solution was evaporated under reduced pressure using a rotary evaporator. The solution was then dried overnight at 37 °C in a vacuum drying oven. The residue was added to 2-3 mL of toluene and heated to 90 °C until completely dissolved. The mixture was then slowly cooled to room temperature, and colorless crystals were obtained after 3 days at room temperature. The colorless crystals obtained in this example were taken as compound 4, and their structural formula is shown below. The yield of the crystalline product prepared in this example was tested to be 89%. 1 H NMR such as Figure 4 As shown.

[0035]

[0036] Example 5 1.50 g of dibutyltin oxide, 1.13 g of 1-adamantaneacetic acid, and 150 mL of toluene were added to a 250 mL round-bottom flask equipped with a Dean-Starck apparatus and a condenser. The mixture was refluxed under nitrogen protection for 10 h until completely dissolved. After the reaction, the mixture was cooled to room temperature, and the solution was evaporated under reduced pressure using a rotary evaporator. The solution was then dried overnight at 37 °C in a vacuum drying oven. The residue was added to 2-3 mL of toluene and heated to 90 °C until completely dissolved. The mixture was then slowly cooled to room temperature, and colorless crystals were obtained after 3 days at room temperature. The colorless crystals obtained in this example were taken as compound 5, and their structural formula is shown below. The yield of the crystalline product prepared in this example was tested to be 92%. 1 H NMR such as Figure 5 As shown.

[0037]

[0038] Example 6 1.50 g of dibutyltin oxide, 1.05 g of 2-adamantane carboxylic acid, and 150 mL of toluene were added to a 250 mL round-bottom flask equipped with a Dean-Starck apparatus and a condenser. The mixture was refluxed under nitrogen protection for 10 h until completely dissolved. After the reaction, the mixture was cooled to room temperature, and the solution was evaporated under reduced pressure using a rotary evaporator. The solution was then dried overnight at 37 °C in a vacuum drying oven. The resulting residue was added to 2-3 mL of toluene and heated to 90 °C until completely dissolved. The mixture was then slowly cooled to room temperature, and colorless crystals were obtained after 3 days at room temperature. The colorless crystals obtained in this example were taken as compound 6, and their structural formula is shown below. 1 H NMR such as Figure 6 As shown.

[0039]

[0040] Application examples Applications of tin-oxygen metal clusters coordinated with dialkyl and organic cyclic carboxylic acids in extreme ultraviolet lithography and electron beam lithography: 15 mg of each of the dialkyl and cyclic organic carboxylic acid-coordinated tin oxide cluster compounds prepared in Examples 1-6 were accurately weighed using a 0.01 g / mL balance and added to 1 mL of chloroform solution. The solutions were ultrasonically vibrated for 20 min and then filtered three times through a 0.22 μm PTFE membrane to obtain a photoresist solution. 40 μL of the photoresist solution was dropped onto a 1 cm * 1 cm wafer, rotated at 6000 rpm for 30 s, and then baked at 70 °C for 1 min to obtain a smooth film with a thickness of approximately 30-40 nm.

[0041] Test case Test Example 1 Thin films prepared from the compounds provided in Examples 1-6 using the method described in the application examples were used to test the contrast curves of the photoresist films. The accelerating voltage was 1 kV, each block was 5 μm * 5 μm with a spacing of 5 μm, for a total of 8 * 8 = 64 blocks, and the dose was 10 - 640 μC / cm. 2 After exposure, bake at 100 °C for 1 min, develop in IPA:DIW = 3:1 developer for 20 s, fix in DIW for 5 s, and finally harden at 100 °C for 30 s. Measure the height of each small square using AFM, normalize the result, and plot a contrast curve against the corresponding dosage. During the thickness increase phase, i.e., between the points where the thickness (after normalization) is 0.2–0.8, fit a straight line. The x-value corresponding to the intersection with the x-axis is D0, and the x-value corresponding to the intersection with the line y = 1 is D. 100 The corresponding contrast ratio is calculated using the following formula:

[0042] The contrast ratios of the compounds prepared in Examples 1-6 can be calculated and are shown in Table 2 and... Figure 7 .

[0043] Table 2. Contrast ratios of the crystals provided in Examples 1-6

[0044] Combination Figure 2 and Figure 7 It is known that the contrast of compounds 1-3 is between 1 and 2, which is suitable for currently commercial photoresists. In the process of periodic line patterning, it is easy to obtain lines with more vertical sidewalls.

[0045] Test Example 2 Thin films made from the compounds provided in Examples 1-3 using the method described in the application examples were then subjected to periodic line patterning. Test results are shown below. Figure 8-10 The accelerating voltage was 1 kV. After exposure, the film was baked at 100 °C for 1 min, developed in a developer solution of IPA:DIW = 3:1 for 20 s, fixed in DIW for 5 s, and finally hardened at 100 °C for 30 s. The lines after development were observed using SEM.

[0046] in Figure 8 The periodic lines formed by the thin film prepared from compound 1 under EBL; in Figure 9 The periodic lines formed by the thin film prepared from compound 2 under EBL; in Figure 10 The periodic lines formed by the thin film prepared from compound 3 under EBL; Combination Figure 8-10 It can be seen that compound 1 formed a line of 40.1 nm, compound 2 formed a line of 44.0 nm, and compound 3 formed a line of 45.7 nm. It can be seen that the Sn-C bond has low bond energy and is prone to generating alkyl radicals, which can trigger a series of polymerization reactions, thus resulting in high sensitivity.

[0047] Test Example 3 The compounds provided in Examples 1-3 were used to prepare a photoresist solution using the method described in the application example. Then, 100 μL of the photoresist solution was dropped onto the center of a 2-inch wafer, rotated at 6000 rpm for 30 s, and then baked at 70 °C for 1 min to form an ultra-smooth film with a thickness of approximately 30 nm. The prepared film was patterned at the Shanghai Synchrotron Radiation Facility (SSRF) using X-ray Interference Lithography (XIL) under EUV (13.5 nm) exposure. This provides a suitable platform for evaluating the performance of EUV photoresists. X-ray Interference Lithography (XIL) is an advanced nanofabrication technique that forms periodic lines through the interference of two beams of light. It has advantages such as large-area fabrication, strict periodicity, and large depth of focus. It is also currently the only method that can achieve testing with a 13.5 nm extreme ultraviolet light source without an EUV lithography machine.

[0048] Exposure doses ranged from 3.7 to 149.85 mJ / cm². 2A total of 100 exposure doses were performed, and post-processing (baking, developing, fixing, and hardening) was carried out using the same method as in the application example, resulting in L / S periodic lines with a half-pitch of 50 nm. These lines were observed using SEM, and their critical linewidths were measured. The test results are shown in [reference needed]. Figure 11-13 .

[0049] like Figure 11-13 As shown, compound 1 at 40.9 mJ / cm 2 At the specified dosage, a line 53.0 nm wide was obtained for compound 2 at 48.7 mJ / cm². 2 At a dose of [specific value], a line 50.0 nm wide was obtained, while the compound [achieved] at 58.9 mJ / cm [value]. 2 At a certain dosage, lines with a width of 50.0 nm were obtained, indicating that the higher the Sn-C bond energy, the higher the resolution of the patterning.

[0050] Test Example 4 Thin films prepared from the compounds provided in Examples 1-2 using the method described in the application examples were subjected to etching rate measurements under deep silicon etching and reactive ion etching. Based on the EBL exposure results, three lines with a width of 15 μm, a length of 75 μm, and a spacing of 15 μm were patterned on two types of tin oxide cluster films on a 1 cm * 1 cm silicon wafer under the same conditions and with appropriate exposure dose. The changes in line thickness before and after etching were tested. The experiment was conducted using SPTS Technologies' OMEGA-ICP and Oxford Instruments' RIE-180. The etching conditions and parameters are shown in Table 3 below. The changes in line thickness and contour before and after etching were measured by AFM.

[0051] Table 3 Etching conditions and parameters

[0052] To accurately calculate the etching rates of the two types of cluster films, the thickness change of the silicon substrate before and after the two etching processes was also measured using AFM. Before etching, adhesive tape was tightly attached to a 1 cm * 1 cm empty silicon wafer. After etching, the tape was removed, and the silicon wafer was cleaned with acetone. The thickness change at the cross-section was measured using AFM, thus determining the etching rate of the silicon substrate. The thickness of the silicon wafer after etching is shown in the figure. Figure 14 As shown, the etching rates of the silicon substrate under the two etching conditions are calculated to be 3.94 nm / s and 2.92 nm / s, respectively, using the following formula.

[0053] Etching rate = (Initial thickness - Post-etching thickness) / Etching time Etching experiments were conducted under the same conditions on the patterned lines of the two types of cluster thin films. The thickness change before and after deep silicon etching is as follows: Figure 15 As shown, the thickness change before and after RIE etching is as follows: Figure 16 As shown, after calculation, the etching rates for deep silicon etching are 0.91 nm / s and 0.93 nm / s, exhibiting excellent etching selectivity and an etching rate ratio of 1:4.3. In contrast, the etching rates for RIE (Reactive Ion Etching) are 1.45 nm / s and 1.49 nm / s, with an etching rate ratio of 1:2.0.

[0054] In summary, tin-oxygen metal clusters coordinated with dialkyl and organic cyclic carboxylic acids offer the advantages of high resolution, high sensitivity, and high etching resistance.

[0055] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A class of tin-oxygen metal clusters coordinated with dialkyl and organic cyclic carboxylic acids, characterized in that, The tin oxide metal cluster has the following general formula I structure. 。 2. The method for synthesizing a type of tin-oxygen metal cluster coordinated with dialkyl and organic cyclic carboxylic acids as described in claim 1, characterized in that, include: 1.50 g of dibutyltin oxide, 1.05 g of 1-adamantane carboxylic acid, and 150 mL of toluene were added to a 250 mL round-bottom flask equipped with a Dean-Starck apparatus and a condenser. The mixture was refluxed under nitrogen protection for 10 h until completely dissolved. After the reaction was completed, the mixture was cooled to room temperature and evaporated under reduced pressure using a rotary evaporator. The solution was then dried overnight at 37 °C in a vacuum drying oven. The residue was added to 2-3 mL of toluene and heated to 90 °C until completely dissolved. The mixture was then slowly cooled to room temperature. After 3 days at room temperature, colorless crystals were obtained, which were tin-oxygen metal clusters.

3. The application of the dialkyl and organic cyclic carboxylic acid coordinated tin-oxygen metal clusters as described in claim 1 in extreme ultraviolet lithography and electron beam lithography, characterized in that, The tin-oxygen metal clusters serve as photosensitizers and resins in the photoresist formulation.

4. The application according to claim 3, characterized in that, The photoresist was prepared by adding chloroform to a tin-oxygen metal cluster, ultrasonicating for 20 minutes, and then filtering to obtain a photoresist solution.

5. The application according to claim 3, characterized in that, The tin oxide metal clusters serve as photosensitizers and resins in electron beam photoresist formulations, enabling the patterning of 100 nm linewidth lines in electron beam lithography.

6. The application according to claim 3, characterized in that, The tin-oxygen metal clusters, as photosensitizers and resins in extreme ultraviolet (EUV) photoresist formulations, can pattern 50 nm linewidth and 100 nm periodic lines during EUV lithography exposure.

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