Fabrication of EUV masks using a combination of monolayer lithography and area selective deposition

Abstract

A surfactant or photoacid generator (PAG) that forms a self-assembled monolayer is deposited on the substrate surface. Irradiation of the substrate surface with electron beam (e-beam) and / or extreme ultraviolet (EUV) radiation creates a negative or positive pattern on the monolayer. Hydroxamic acids can be used to form negative self-assembled monolayers, while silanes or PAGs can be used to form positive self-assembled monolayers. Area-selective deposition of an EUV-absorbing material onto the negative- or positive-patterned monolayer forms a negative- or positive-EUV-absorbing mask, respectively.

Description

[Technical Field]

[0001] The present invention relates generally to extreme ultraviolet (EUV) masks fabricated by a combination of monolayer lithography and selective area deposition, and more particularly to EUV masks fabricated by lithographic patterning of self-assembled monolayers on a substrate surface and selective area deposition of an EUV-absorbing material onto the patterned monolayer. [Background technology]

[0002] High-numerical-aperture (NA) EUV lithography poses two requirements for EUV absorbers: greater than 85% contrast and less than 30 nm thickness. Platinum (Pt) and tellurium (Te) are two examples of materials that meet the requirements for high-NA EUV lithography. However, these two materials are not suitable for conventional EUV patterning. Etching requires the generation of volatile species for patterning, and therefore, etch-resistant materials such as Pt and Te cannot be used for conventional EUV patterning. Currently, EUV mask fabrication requires patterning by conventional deposition and etching using the absorber tantalum nitride (TaN). TaN has a contrast of approximately 75% and a thickness of more than 60 nm, which does not meet the requirements for high-NA EUV lithography. To achieve high-NA EUV lithography, EUV mask fabrication will require advances beyond currently used absorber materials and / or conventional techniques. Summary of the Invention

[0003] The present invention overcomes the need in the art by providing a method for fabricating an EUV mask that does not require etching, thereby enabling the use of etch-resistant absorbers that meet the requirements of high NA EUV lithography.

[0004] In one embodiment, the present invention relates to a composition comprising: a substrate having a top surface and a bottom region; a self-assembled monolayer attached to the top surface of the substrate, where the self-assembled monolayer comprises a surfactant or a photoacid generator; and an EUV absorbing film comprising at least one EUV absorbing material, where the EUV absorbing material is associated with the self-assembled monolayer in a negative or positive pattern.

[0005] In another embodiment, the present invention relates to a method for making a positive or negative EUV mask, the method comprising the steps of depositing a surfactant or a photoacid generator on a substrate, where the surfactant and / or photoacid generator self-aligns on the surface of the substrate to form a monolayer; exposing the monolayer patternwise to e-beam or EUV radiation to form a resist pattern; and depositing an EUV absorbing material on the monolayer, where the EUV absorbing material combines with the unexposed areas of the monolayer to form a negatively patterned EUV mask or combines with the exposed areas of the monolayer to form a positively patterned EUV mask.

[0006] In a further embodiment, the present invention relates to a method for making a negative EUV mask, comprising the steps of depositing hydroxamic acids having polar heads and non-polar tails on a substrate having a metal surface, wherein the hydroxamic acids self-align to form a monolayer through interaction of the polar heads of the hydroxamic acids with the metal surface of the substrate; exposing the monolayer to e-beam or EUV radiation in a pattern, wherein the monolayer is cross-linked in areas exposed to e-beam or EUV radiation and not cross-linked in areas not exposed to e-beam or EUV radiation; and depositing an EUV-absorbing material on the monolayer, wherein the EUV-absorbing material bonds with the non-polar tails of the hydroxamic acids on the unexposed, non-cross-linked areas of the monolayer to form a negative EUV mask.

[0007] In another embodiment, the present invention relates to a method for making a positive EUV mask, comprising the steps of depositing silanes on a substrate, where the silanes have reactive heads and non-reactive tails, and where the silanes self-align to form a monolayer by interaction of the heads with the upper surface of the substrate; treating the monolayer with e-beam or EUV radiation in a patterned manner, where the e-beam or EUV radiation activates the silane tails by generating polar groups on the silane tails only in the areas of the monolayer exposed to the e-beam or EUV radiation; and depositing an EUV-absorbing material on the treated monolayer, where the EUV-absorbing material combines with the polar groups on the silane tails to form a positive EUV mask.

[0008] In a further embodiment, the present invention relates to a method for fabricating a positive tone EUV mask, comprising the steps of depositing a photoacid generator (PAG) on a substrate, the PAG having a reactive head group and a non-reactive tail group, where the PAG self-aligns to form a polymer brush monolayer by interaction of the head groups with the upper surface of the substrate; treating the PAG patternwise with e-beam or EUV radiation, where the e-beam or EUV radiation activates the tail group of the PAG by generating a polar acid in the tail group of the PAG only in the areas of the polymer brush monolayer exposed to the e-beam or EUV radiation; and depositing an EUV absorbing material on the treated polymer brush monolayer, where the EUV absorbing material combines with the polar acid in the tail group of the PAG to form a positive tone EUV mask.

[0009] In another embodiment, the substrate is a metal-capped substrate and the surfactant has a polar head group containing 3 to 24 carbon atoms that chelates to the metal capping the substrate and a non-polar tail group that binds the EUV absorbing material in a negative pattern.

[0010] In a further embodiment, the metal surface of the substrate is selected from the group consisting of ruthenium, palladium, platinum, titanium, tantalum, nickel, copper, aluminum, and combinations thereof.

[0011] In another embodiment, the surfactant is an organosilicon compound with a reactive head that adheres to the substrate and a polar tail that binds the EUV absorbing material in a positive pattern.

[0012] In further embodiments, the EUV absorbing material is selected from the group consisting of platinum, tellurium, zinc, titanium, antimony, indium, bismuth, silver, and combinations thereof.

[0013] In another embodiment, the self-assembled monolayer has cross-linked and non-cross-linked regions, and the EUV absorbing material is deposited in a negative pattern only on the non-cross-linked regions of the self-assembled monolayer.

[0014] In a further embodiment, the crosslinked regions of the monolayer are removed from the negative EUV mask using a reducing agent selected from the group consisting of H2 plasma, N2 plasma, NH3 plasma, and combinations thereof.

[0015] In another embodiment, the negative EUV mask is augmented with a compound selected from the group consisting of phosphonic acid, phosphonic acid derivatives, stearic acid, stearic acid derivatives, and combinations thereof.

[0016] In further embodiments, the hydroxamic acid is selected from the group consisting of unsubstituted hydroxamic acid, methylhydroxamic acid, tetrahydroxamic acid, hexylhydroxamic acid, octylhydroxamic acid, cyclohexylhydroxamic acid, octadecylhydroxamic acid, dodecylhydroxamic acid, and combinations thereof.

[0017] In another embodiment, the hydroxamic acid further comprises a reactive group selected from the group consisting of an alkene, an alkyne, a glycidyl group, and combinations thereof.

[0018] In further embodiments, the silane is selected from the group consisting of aminosilanes, ethoxysilanes, chlorosilanes, glycidoxysilanes, methacryloxysilanes, methoxysilanes, N-alkylsilanes, mercaptosilanes, and combinations thereof.

[0019] In another embodiment, the PAG is a polymer brush with a reactive head that attaches to the substrate and a polar tail that binds the EUV absorbing material in a positive pattern.

[0020] In a further embodiment, the PAG is an ionic PAG selected from the group consisting of diaryliodonium salts, triarylsulfonium salts, naphthalimide sulfonic acids, and combinations thereof.

[0021] In another embodiment, the PAG is a non-ionic PAG selected from the group consisting of iminosulfonic acids, imidosulfonic acids, benzylsulfonic acids, and combinations thereof.

[0022] Additional aspects and / or embodiments of the present invention are provided in the detailed description of the invention set forth below, without limitation. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is a schematic diagram showing the fabrication of a negative EUV mask.

[0024] [Figure 2] Schematic diagram showing the fabrication of a negative EUV mask using different surfaces.

[0025] [Figure 3]Film thickness contrast curves for two negative-tone zinc oxide (ZnO) EUV masks: one fabricated using an unsubstituted hydroxamic acid self-assembled monolayer (SAM), and the other fabricated using a SAM of methylhydroxamic acid and ZnO.

[0026] [Figure 4] Atomic layer deposition (ALD) exposure results of the EUV absorber ZnO on two negative resists, one made with an unsubstituted hydroxamic acid SAM and the other with a methylhydroxamic acid SAM.

[0027] [Figure 5] Figure 1 shows the ALD exposure results of ZnO onto three negative resists: one made with a SAM of unsubstituted hydroxamic acid, one made with a SAM of methylhydroxamic acid, and one made with a SAM of cyclohexylhydroxamic acid.

[0028] [Figure 6] Shown are film thickness contrast curves measured by Rutherford backscattering spectroscopy (RBS) for three ZnO negative EUV masks exposed to EUV doses ranging from 0 to 205 mJ / cm2; one prepared with a SAM of unsubstituted hydroxamic acid, one with a SAM of methylhydroxamic acid, and one with a SAM of cyclohexylhydroxamic acid.

[0029] [Figure 7]The figure shows the contrast curves measured by x-ray photoelectron spectroscopy (XPS) for three ZnO negative EUV masks exposed to EUV doses ranging from 1 to 205 mJ / cm2; one prepared with a SAM of cyclohexylhydroxamic acid, another with phosphonic acid, and a third with octadecanethiol (ODT).

[0030] [Figure 8] FIG. 1 is a schematic diagram showing different packing densities of hydroxamic acid, methylhydroxamic acid, and cyclohexylhydroxamic acid.

[0031] [Figure 9] FIG. 1 is a schematic showing how phosphonic acid enhances the contrast of hydroxamic acid SAMs in area-selective deposition.

[0032] [Figure 10] FIG. 1 is a schematic diagram illustrating the fabrication of a positive EUV mask on a substrate using a silane SAM.

[0033] [Figure 11] Contrast curves for two positive titanium dioxide (TiO2) masks, one made with 50 mol% trichlorophenylsilane (TPS) and the other with 10 mol% TPS.

[0034] [Figure 12A] FIG. 1 shows examples of non-ionic PAGs. [Figure 12B] FIG. 1 shows examples of polymers incorporating non-ionic PAGs.

[0035] [Figure 13A] FIG. 12C shows contrast curves for the SAM of the non-ionic PAG of FIG. 12B, exposed at 193 nm, before and after development. [Figure 13B]FIG. 12C shows contrast curves for the SAM of the non-ionic PAG of FIG. 12B, before and after development, when exposed at 248 nm. [Figure 13C] FIG. 12C shows the contrast curves for the SAM of the non-ionic PAG of FIG. 12B after EUV exposure and development. DETAILED DESCRIPTION OF THE INVENTION

[0036] Set forth below are descriptions of what are presently believed to be preferred aspects and / or embodiments of the present invention. Any alternatives or modifications in function, purpose, or structure are intended to be encompassed by the appended claims. As used in this specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. The terms "comprise," "comprised," "comprises," and / or "comprising," as used in this specification and the appended claims, specify the presence of explicitly stated components, elements, features, and / or steps, but do not preclude the presence or addition of one or more other components, elements, features, and / or steps.

[0037] As used herein, the terms "photolithography" and "lithography" refer to the creation of finely patterned thin films on a substrate to protect selected areas of the substrate during microchip fabrication.

[0038] As used herein, the term "EUV lithography" currently refers to lithography using light having a wavelength of 13.5 nm.

[0039] As used herein, the term "EUV radiation" means light having photons with energies in the range of 10 eV to 124 eV and wavelengths in the range of 10 nm to 100 nm.

[0040] As used herein, the term "electron-beam radiation" or "e-beam radiation" means the delivery of high-energy electrons from an electron beam accelerator to a material to induce a change (such as cross-linking) in the material.

[0041] As used herein, the term "EUV mask" refers to a photolithographic thin film having (i) an EUV absorbing layer deposited on multiple layers of EUV substrate material (e.g., 40-50 layers of molybdenum and silicon); (ii) a pattern defined on the EUV absorbing layer; and (iii) a surface that reflects light from the patterned areas of the EUV absorbing layer. EUV masks differ from conventional photolithographic masks because they are made of reflective surfaces and light-blocking elements that form a pattern upon exposure to ultraviolet radiation (which can be e-beam and / or EUV radiation). The latter of these masks is an opaque film or plate with holes or transparent areas that allow light to pass through between the defined patterns. EUV masks described herein can be negative or positive.

[0042] As used herein, the term "substrate" means the base material on which a process is performed.

[0043] As used herein, the terms "self-assembled monolayer" and "SAM" refer to a layer of material one molecule thick that binds to a substrate surface in an ordered fashion as a result of physical or chemical forces during a deposition process.

[0044] As used herein, the term "resist" refers to a layer that is applied to a substrate. In the context of the present invention, the term "resist" is used to refer to a layer on a substrate that is ultimately converted into an EUV mask upon deposition of an EUV absorber on a self-assembled monolayer on the substrate.

[0045] As used herein, the term "area selective deposition" or "ASD" refers to a bottom-up process that results in uniform deposition in selected areas of a patterned substrate. In the context of the present invention, area selective deposition is used to deposit an EUV absorber onto an EUV substrate, the latter having a surfactant monolayer on the top surface.

[0046] As used herein, the term "chemical vapor deposition" or "CVD" refers to a method of area-selective deposition using a vacuum environment to form thin films. With CVD, a substrate is exposed to one or more volatile precursors that react and / or decompose on the substrate surface to deposit material. With CVD, volatile by-products may be produced, which are typically removed by gases flowing through the reaction chamber. In the context of the present invention, CVD may be used for area-selective deposition of EUV absorbers on EUV masks.

[0047] As used herein, the term "atomic layer deposition" or "ALD" refers to a method of area-selective deposition that uses a gas-phase chemical process to form thin films. ALD is considered a subclass of CVD. ALD reactions use two gaseous precursor chemicals that react with the substrate surface, one at a time, in a sequential, non-overlapping manner. In this manner, thin films are gradually deposited through repeated exposure to different precursors. Unlike CVD, the precursors in ALD are not present simultaneously. In the context of the present invention, ALD can also be used for area-selective deposition of EUV absorbers on EUV masks. In the context of the present invention, examples of materials that can be used in ALD include zinc oxide (ZnO), platinum (Pt), titanium dioxide (TiO), or tellurium (Te).

[0048] Described herein is an additive approach to fabricating high-NA EUV masks, in which an EUV absorber is patterned onto a surfactant-treated substrate, where the surfactant is a patternable self-assembled monolayer. This additive approach enables the patterned addition of robust EUV absorbing films, such as Pt and / or Te films, which are difficult to pattern using conventional deposition and etching techniques. The EUV absorbing material can be deposited onto the surfactant-treated substrate by selective area deposition (CVD) or ALD without damaging the underlying substrate. The combination of the patternable surfactant monolayer and selective area deposition of the EUV absorber enables the fabrication of customized EUV masks. Because this additive approach does not require an etching step, it enables the fabrication of EUV masks using highly etch-resistant absorbers, such as Pt and / or Te. Therefore, the fabrication of the EUV masks described herein utilizes a combination of monolayer lithography and selective area deposition. A surfactant self-assembled monolayer on a substrate surface is patterned using monolayer lithography, and an EUV mask is fabricated by selectively depositing an EUV absorber onto the patterned surfactant monolayer.

[0049] In one embodiment, the high NA EUV absorber comprises a chemical selected from the group consisting of platinum (Pt), tellurium (Te), zinc (Zn), titanium (Ti), antimony (Sb), indium (In), bismuth (Bi), silver (Ag), and combinations thereof.

[0050] In another embodiment, the surfactant used to form the self-assembled monolayer has 3 to 42 carbon atoms. In another embodiment, the surfactant has a polar head and a non-polar tail. In a further embodiment, the surfactant has reactive side groups that assist the surfactant in self-assembly into a monolayer. Such reactive side groups include, but are not limited to, alkenes, alkynes, glycidyl groups, and combinations thereof. Examples of surfactants that can be used to form the self-assembled monolayer include, but are not limited to, hydroxamic acids and their derivatives (collectively referred to herein as "hydroxamic acids"), silanes and their derivatives (collectively referred to herein as "silanes"), and photoacid generators (PAGs).

[0051] Hydroxamic acids are organic compounds with the formula RC(O)N(OH)R′, where CO is a carbonyl group, R is an organic residue, and R′ is H or an organic residue. Hydroxamic acids generally consist of a polar hydroxamic head, a hydrophobic methylene spacer, a second polar head, and a terminal nonpolar hydrophobic group. In the context of the present invention, the polar head of the hydroxamic acid binds tightly to metal ions on the surface of a substrate material to form a self-assembled monolayer. The iron-chelated polar head of the hydroxamic acid crosslinks upon exposure to e-beam and / or EUV radiation. An EUV absorber is covalently attached to the nonpolar tail of the hydroxamic acid using ALD or CVD. The hydroxamic acids that can be used in the self-assembled monolayers described herein can be substituted or unsubstituted. Examples of hydroxamic acids include, but are not limited to, unsubstituted hydroxamic acid, methylhydroxamic acid, n-butylhydroxamic acid, n-hexylhydroxamic acid, n-octylhydroxamic acid, cyclohexylhydroxamic acid, octadecylhydroxamic acid, dodecylhydroxamic acid, and combinations thereof. Example 1 describes a negative EUV mask fabricated using a self-assembled monolayer of hydroxamic acid.

[0052] Silane is a type of electrically neutral silicon compound with the chemical formula Si n R 2n+2 where n = 1, 2, 3, 4, etc., and the R substituents can be organic groups, inorganic groups, or combinations thereof. Most silanes are organosilicon compounds containing Si-C bonds. Silanes used as self-assembled monolayers generally consist of a reactive head group containing silicon and a non-reactive tail group. In the context of the present invention, the reactive head group of the silane bonds with any suitable substrate surface to form a self-assembled monolayer. Upon exposure to e-beam and / or EUV radiation, followed by exposure to oxygen, the non-reactive tail group of the silane becomes reactive and chemically bonds with oxygen, converting the silane tail into a reactive polar group containing at least one hydroxyl group (-OH) and / or carbonyl group (-COOH). Examples of silanes that can be used in the self-assembled monolayers described herein include, but are not limited to, aminosilanes, ethoxysilanes, chlorosilanes, glycidoxysilanes, methacryloxysilanes, methoxysilanes, N-alkylsilanes, mercaptosilanes, and combinations thereof. In Example 2, a positive EUV mask fabricated using a self-assembled monolayer of silane will be described.

[0053] When PAG is irradiated with light of a certain wavelength, it decomposes and releases protons (H + PAGs are organic compounds that generate a polar acid (i.e., generate a polar acid). PAGs are classified into two groups: ionic PAGs and non-ionic PAGs. Examples of ionic PAGs include, but are not limited to, diaryliodonium salts, triarylsulfonium salts, naphthalimide sulfonic acids, and combinations thereof. Examples of non-ionic PAGs include, but are not limited to, iminosulfonic acids, imidosulfonic acids, benzylsulfonic acids, and combinations thereof. Example 3 describes a positive EUV mask fabricated using a self-assembled monolayer of PAG.

[0054] In one embodiment, the EUV mask is negative, the self-assembled monolayer is a hydroxamic acid, and the patterning is performed using e-beam and / or EUV radiation. The patterning is performed by patternwise e-beam and / or EUV radiation, crosslinking the exposed areas of the surfactant-treated SAM while not crosslinking the unexposed areas. When an EUV absorber is deposited on the treated and irradiated SAM, the EUV absorber grows only on the areas of the treated SAM that are not exposed to e-beam and / or EUV radiation.

[0055] In another embodiment, after e-beam and / or EUV exposure and before deposition of the EUV absorbing material, the hydroxamic acid monolayer is treated with or replaced with a contrast enhancing agent. Examples of contrast enhancing materials that can be applied to the surfactant monolayer include, but are not limited to, phosphonic acid, phosphonic acid derivatives, stearic acid, stearic acid derivatives, and combinations thereof.

[0056] In a further embodiment, the crosslinked regions of the hydroxamic acid monolayer are removed from the EUV mask substrate using a reducing agent selected from the group consisting of H2 plasma, N2 plasma, NH3 plasma, and combinations thereof.

[0057] In another embodiment, the substrate of the negative EUV mask is coated with a metal selected from the group consisting of ruthenium, palladium, platinum, titanium, tantalum, nickel, copper, aluminum, and combinations thereof. In a further embodiment, the substrate of the negative EUV mask comprises silicon, silicon dioxide, beryllium, molybdenum, and combinations thereof. In another embodiment, the substrate is a multilayer thin film comprising silicon, silicon dioxide, beryllium, molybdenum, and combinations thereof. In a further embodiment, the substrate is a multilayer thin film comprising molybdenum silicon (Mo / Si) or molybdenum beryllium (Mo / Be). In another embodiment, the substrate is planar. In a further embodiment, the substrate is coplanar.

[0058] Figure 1 shows a schematic of the fabrication of a negative EUV mask. Here, a monolayer of hydroxamic acid is deposited on a Ru-covered Mo / Si multilayer substrate, the monolayer is patterned by e-beam to crosslink the hydroxamic acid, high-NA EUV absorbers Pt or Te are negatively atomic-layer deposited (on the unexposed areas), and the crosslinked areas of the negative EUV mask are removed by H2 plasma.

[0059] Figure 2 shows a schematic of how the negative resists described herein can be adapted based on the planar configuration of the substrate surface. The negative process shown in Figure 1 produces a barrier-like negative pattern (top panel), while using a negative process on a coplanar surface produces a grid-like negative pattern.

[0060] Figure 3 shows the resist contrast versus exposure dose curve for zinc oxide (ZnO) film thickness measured using Rutherford backscattering spectroscopy (RBS) for two negative EUV masks fabricated using zinc oxide (ZnO) as the EUV absorber. One resist was fabricated using 600 ALD cycles of ZnO with a SAM of unsubstituted hydroxamic acid, while the other was fabricated using 300 ALD cycles of ZnO with a SAM of methylhydroxamic acid. Both resists were fabricated using 0–205 mJ / cm. 2 The resists made with unsubstituted hydroxamic acids were exposed to EUV doses ranging from 205 mJ / cm 2 At an EUV dose of 1000 mJ / cm, the mask was exposed to 2 of EUV) and unexposed (0 mJ / cm 2 The resist made with methylhydroxamic acid showed the highest contrast between the EUV (EUV) region and the 70 mJ / cm 2 The maximum contrast between exposed and unexposed areas of the mask was observed at an exposure dose of 205 mJ / cm 2 The results remained constant up to an exposure dose of 1000 s.

[0061] Figure 4 shows the atomic layer deposition of the EUV absorber zinc oxide (ZnO) on two negative resists prepared with a fixed exposure dose of 205 mJ / cm. One resist was prepared with a SAM of unsubstituted hydroxamic acid, and the other with a SAM of methylhydroxamic acid. The amount of ZnO growth over 600 ALD cycles is shown for the exposed and unexposed regions of each resist. ZnO grew from 0 to 40 nm in thickness on the unexposed (i.e., uncrosslinked) regions of the negative resist prepared with methylhydroxamic acid, while ZnO grew from 0 to 15 nm in thickness on the unexposed regions of the negative resist prepared with unsubstituted hydroxamic acid. In both resists, no ZnO grew on the exposed (i.e., crosslinked) regions of the SAM.

[0062] Figure 5 shows the atomic layer deposition of ZnO onto three negatively patterned resists. One resist was fabricated with a SAM of unsubstituted hydroxamic acid and was not exposed to EUV radiation. The other resist was fabricated with a SAM of methylhydroxamic acid and was exposed to 205 mJ / cm. 2 The third one uses a SAM of cyclohexylhydroxamic acid and is exposed to EUV at 205 mJ / cm. 2 The unsubstituted hydroxamic acid SAMs that were not exposed to EUV radiation show no growth after 500 ALD cycles. In contrast, the exposed methylhydroxamic acid shows ZnO growth to 27 nm after 400 ALD cycles, and the exposed cyclohexylhydroxamic acid shows ZnO growth to 14.6 nm after 400 ALD cycles.

[0063] Figure 6 shows the ZnO film thickness versus exposure dose curves, showing the resist contrast, measured using RBS, for three negative resists. One resist was made with a SAM of unsubstituted hydroxamic acid, another with a SAM of methylhydroxamic acid, and the third with a SAM of cyclohexylhydroxamic acid. All resists were measured at exposure doses ranging from 0 to 200 mJ / cm. 2 The resists were exposed to EUV doses ranging from 205 mJ / cm to 205 mJ / cm. RBS was used to measure the thickness in nm of the ZnO at different EUV doses. The resist fabricated with a SAM of unsubstituted hydroxamic acid was exposed to 205 mJ / cm. 2 The resist made with a SAM of methylhydroxamic acid showed the greatest contrast between exposed and unexposed areas of the mask at an EUV dose of 70 mJ / cm. 2 At an EUV dose of 205 mJ / cm2, the maximum contrast between exposed and unexposed areas of the mask was observed. 2 The resist made with a SAM of cyclohexylhydroxamic acid remained constant up to an exposure dose of 65 mJ / cm. 2 At an EUV dose of 205 mJ / cm2, the maximum contrast between exposed and unexposed areas of the mask is observed. 2 The contrast curves for the unsubstituted hydroxamic acid SAM and the methylhydroxamic acid SAM are consistent with those shown in FIG.

[0064] Figure 7 shows the resist contrast curves generated by X-ray photoelectron spectroscopy (XPS) for three types of negative resists. One resist was prepared using a SAM of cyclohexylhydroxamic acid, another was prepared using a monolayer of phosphonic acid, and the third was prepared using a monolayer of octadecanethiol (ODT). All of these resists were in the range of 0 to 205 mJ / cm. 2The resists were exposed to EUV doses ranging from 205 mJ / cm to 205 mJ / cm. XPS was used to measure the Zn fraction at different EUV doses. The resist fabricated with a SAM of cyclohexylhydroxamic acid was exposed to 205 mJ / cm. 2 At 1000 nm, the maximum contrast between exposed and unexposed regions of the mask was observed. Resists prepared with phosphonic acid did not show ZnO adhesion to the phosphonic acid and therefore could not be used to form EUV masks. Resists prepared with ODT showed ZnO adhesion to the ODT but did not show any significant change in the ZnO fraction at any EUV dose. Figure 7 demonstrates that, unlike phosphonic acid and ODT, the hydroxamic acid SAMs described herein can form functional EUV masks.

[0065] FIG. 8 is a schematic diagram showing the different packing densities of hydroxamic acid, methylhydroxamic acid, and cyclohexylhydroxamic acid.

[0066] Figure 9 shows a schematic diagram of how phosphonic acid increases the contrast of a hydroxamic acid self-assembled monolayer during area-selective deposition. The phosphonic acid removes uncrosslinked hydroxamic acid from the surface of the SAM in the unexposed, crosslinked regions of the SAM, thereby increasing the contrast between the unexposed and exposed regions of the SAM during ASD.

[0067] In a further embodiment, the EUV mask is positive-tone, the self-assembled monolayer is made of silane, and the patterning is performed using e-beam and / or EUV radiation (collectively referred to as "exposure"). The patternwise exposure of the SAM with silane results in the exposed regions becoming reactive and the unexposed regions remaining unreactive, because the unreactive silane molecular tails become reactive upon exposure by generating polar groups. When an EUV absorber is deposited on the irradiated and / or optically treated SAM, the EUV absorber grows only in the exposed regions of the SAM. Any suitable substrate can be used to form a positive-tone EUV mask using silane. Examples of substrate materials include, but are not limited to, silicon, silicon dioxide, ruthenium, molybdenum, and combinations thereof.

[0068] Figure 10 shows a schematic of the fabrication of a positive EUV mask: a monolayer of silane is placed on a substrate, which is patterned with an e-beam to activate the non-reactive tails of the silane by creating polar groups, followed by positive atomic layer deposition of high-NA EUV absorbers, Pt or Te.

[0069] Figure 11 shows contrast curves of two types of positive EUV masks prepared using titanium dioxide (TiO2), an EUV absorber, as a function of resist film thickness. One resist was prepared using a SAM of 50 mol% trichloro(octadecyl)silane and 50 mol% trichlorophenylsilane (TPS), while the other resist was prepared using a SAM of 90 mol% trichloro(octadecyl)silane and 10 mol% TPS. Both resists were prepared using a SAM of 0 to 280 mJ / cm2. 2 Both positive resists were exposed to EUV doses ranging from 280 mJ / cm 2 At an EUV dose of 1000 mJ / cm, the mask was exposed to 2 of EUV) and unexposed (0 mJ / cm 2At each EUV dose, the resist with 50 mol% TPS had a slightly larger TiO2 thickness (approximately 0.1-0.3 nm thicker) compared to the resist with 10 mol% TPS.

[0070] In another embodiment, the EUV mask is positive-tone, employing a PAG as a self-assembled monolayer and patterning it using e-beam and / or EUV radiation. The PAG self-assembles onto the substrate surface as a polymer brush monolayer. The polymer brushes consist of a collection of linked long-chain molecules with one end attached to the substrate and the other end extending away from the substrate. As block polymers, the polymer brushes behave differently from free polymer chains. Upon exposure to e-beam and / or EUV radiation, the non-reactive tails of the PAG polymer brushes are converted to polar acids. Any suitable substrate can be used to form a positive-tone EUV mask using the PAG. Examples of substrate materials for positive-tone masks include, but are not limited to, silicon, silicon dioxide, ruthenium, molybdenum, and combinations thereof.

[0071] FIG. 12A shows an example of a non-ionic PAG, and FIG. 12B shows an example of a polyacrylic acid polymer incorporating the PAG of FIG. 12A.

[0072] Figures 13A-13C show the contrast curves for the resist prepared using the nonionic PAG polymer shown in Figure 12B after exposure at 193 nm (Figure 13A), before and after development after exposure at 248 nm (Figure 13B), and after development after exposure at EUV (Figure 13C). After development after exposure at 248 nm, the PAG SAM thickness was 400-450 mJ / cm. 2 After development, the PAG SAM thickness decreased from 575 Å to 0 Å in the dose range of 193 nm; 2After development, the PAG SAM thickness decreased from 625 Å to 0 Å at a dose of 1000 mJ / cm. 2 The sensitivity of the non-ionic PAGs is reduced from 385 Å to 1 Å over the dose range of 248 and 193 nm. These results demonstrate the improved sensitivity of the non-ionic PAGs when exposed to EUV compared to 248 and 193 nm.

[0073] The description of various aspects and / or embodiments of the present invention has been presented for illustrative purposes and is not intended to be exhaustive or limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terms used herein have been selected to best explain the principles of the aspects and / or embodiments, practical applications of technology found in the market, or technical improvements, or to enable those skilled in the art to understand the aspects and / or embodiments disclosed herein. [experiment]

[0074] The following examples are provided to provide those skilled in the art with a full disclosure of how to make and use the aspects and embodiments of the invention described herein. Efforts have been made to ensure accuracy with respect to variables such as dosages, temperatures, and the like, but experimental error and deviation should be accounted for. Unless otherwise indicated, parts are parts by weight, temperatures are in degrees Celsius, and pressures are at or near atmospheric. Unless otherwise indicated, all components were obtained commercially. [Example 1] [Negative EUV mask fabricated using self-assembled monolayers of hydroxamic acids]

[0075] A ruthenium (Ru)-coated molybdenum-silicon (Mo / Si) multilayer structure was immersed in a 4-methyl-2-pentanol solution containing approximately 0.1 wt% hydroxamic acid for up to 30 minutes. The surface was then rinsed with 4-methyl-2-pentanol and dried under a N2 atmosphere. To form a negative EUV mask, the monolayer-coated surface was then subjected to patterned e-beam radiation (EUV radiation can also be used for this step), which crosslinked only the hydroxamic acid in the areas exposed to e-beam radiation. The patterned monolayer was then subjected to atomic layer deposition of ZnO, which was generated through half cycles of diethylzinc and water. This process resulted in growth only on the uncrosslinked areas of the monolayer, and not on the crosslinked areas, resulting in a negative EUV mask (atomic layer deposition of Pt, TiO, or Te would also be effective for this step). The remaining crosslinked self-assembled monolayer was removed with H2 plasma after atomic layer deposition. [Example 2] [Positive EUV mask fabricated using silane self-assembled monolayer]

[0076] A ruthenium (Ru)-coated molybdenum-silicon (Mo / Si) multilayer structure is immersed in a toluene solution containing octadecyltriethoxysilane (1 wt%) for approximately 30 minutes. During this time, the reactive silane reacts with the substrate surface to form a self-assembled monolayer. The silane-bonded substrate surface is then rinsed with toluene, followed by 4-methyl-2-pentanol, and dried under a N2 atmosphere. To form a positive EUV mask, the monolayer-coated surface is patterned with e-beam or EUV radiation and subsequently exposed to ambient air. This combination of irradiation and oxygen exposure activates the non-reactive tails of the silane, generating reactive polar groups with at least one -OH and / or -COOH group. The patterned monolayer is then subjected to atomic layer deposition of ZnO, Pt, TiO, or Te. Here, a film grows on the reactive polar groups, resulting in a positive EUV mask. Any remaining aminosilane that did not bond to the substrate or undergo activation by irradiation is removed with H2 plasma after atomic layer deposition. [Example 3] [Positive EUV mask fabricated using a self-assembled monolayer of a photoacid generator]

[0077] A ruthenium (Ru)-coated molybdenum-silicon (Mo / Si) multilayer structure is immersed in a solution of 1,8-naphthalimidosulfonic acid, an ionic PAG, for approximately 30 minutes. During this time, the ionic PAG bonds with the substrate surface. The ionic PAG-coated substrate surface is then rinsed with 4-methyl-2-pentanol and dried under a N2 atmosphere. To form a positive EUV mask, the monolayer-coated surface is subjected to patternwise e-beam or EUV radiation, which deposits reactive H ions on the monolayer surface. + Polar acid groups are generated. The patterned monolayer is then subjected to atomic layer deposition of ZnO, Pt, TiO2, or Te, where a film grows on the reactive polar acid groups, resulting in a positive EUV mask. Any remaining PAG that did not bond to the substrate or undergo irradiation activation is removed with H2 plasma after atomic layer deposition.

Claims

1. a substrate having a top surface and a bottom region; a self-assembled monolayer attached to the top surface of the substrate, wherein the self-assembled monolayer comprises a surfactant or a photoacid generator; and An extreme ultraviolet (EUV) absorbing film comprising at least one EUV absorbing material, wherein the EUV absorbing material is bonded to the self-assembled monolayer in a negative or positive pattern. A structure comprising:

2. the upper surface of the substrate is covered with a metal, the surfactant contains 3 to 24 carbon atoms and has a polar head that chelates to the metal that coats the substrate, and a non-polar tail that binds the EUV absorbing material in a negative pattern; The construct of claim 1 .

3. 2. The construct of claim 1, wherein the self-assembled monolayer has cross-linked regions and non-cross-linked regions, and the EUV absorbing material is deposited in a negative pattern only on the non-cross-linked regions of the self-assembled monolayer.

4. 10. The structure of claim 1, wherein the surfactant is an organosilicon compound having a reactive head that adheres to the substrate and a polar tail that binds the EUV absorbing material in a positive tone pattern.

5. 10. The structure of claim 1, wherein the photoacid generator is a polymer brush having a reactive head that attaches to the substrate and a polar tail that binds the EUV absorbing material in a positive tone pattern.

6. 10. The structure of claim 1, wherein the EUV absorbing material is selected from the group consisting of platinum, tellurium, zinc, titanium, antimony, indium, bismuth, silver, and combinations thereof.

7. 1. A method for fabricating a positive or negative extreme ultraviolet (EUV) mask, comprising: depositing a surfactant or a photoacid generator on a substrate, wherein the surfactant and / or photoacid generator self-assembles to form a monolayer on the surface of the substrate; exposing the monolayer to an electron beam or EUV radiation in a pattern to form a resist pattern; and depositing an EUV absorbing material over the monolayer, wherein the EUV absorbing material combines with the unexposed areas of the monolayer to form a negatively patterned EUV mask, or combines with the exposed areas of the monolayer to form a positively patterned EUV mask. A method comprising:

8. the substrate is a metallized substrate; 8. The method of claim 7, wherein the surfactant has 3 to 24 carbon atoms and has a polar head that chelates to the metal covering the substrate and a non-polar tail that binds with the EUV absorbing material in a negative tone pattern.

9. 8. The method of claim 7, wherein the self-assembled monolayer has cross-linked regions and non-cross-linked regions, and the EUV absorbing material is bonded only to the non-cross-linked regions of the self-assembled monolayer in a negative tone pattern.

10. 8. The method of claim 7, wherein the surfactant is an organosilicon compound having a reactive head that adheres to the substrate and a polar tail that binds the EUV absorbing material in a positive tone pattern.

11. 8. The method of claim 7, wherein the photoacid generator is a polymer brush having a reactive head that attaches to the substrate and a polar tail that binds the EUV absorbing material in a positive tone pattern.

12. 8. The method of claim 7, wherein the EUV absorbing material is selected from the group consisting of platinum, tellurium, zinc, titanium, antimony, indium, bismuth, silver, and combinations thereof.

13. 1. A method for fabricating a negative extreme ultraviolet (EUV) mask, comprising: depositing a hydroxamic acid having a polar head and a non-polar tail on a substrate having a metal surface, wherein the hydroxamic acid self-assembles to form a monolayer by interaction of the polar head of the hydroxamic acid with the metal surface of the substrate; exposing the monolayer patternwise to electron beam (e-beam) or EUV radiation, wherein the monolayer is crosslinked in the areas exposed to the e-beam or EUV radiation and is not crosslinked in the areas not exposed to the e-beam or EUV radiation; and depositing an EUV absorbing material over the monolayer, wherein in the unexposed, uncrosslinked areas of the monolayer, the EUV absorbing material bonds with the non-polar tails of the hydroxamic acids to form a negative EUV mask. A method comprising:

14. 14. The method of claim 13, wherein the metal surface of the substrate is selected from the group consisting of ruthenium, palladium, platinum, titanium, tantalum, nickel, copper, aluminum, and combinations thereof.

15. 14. The method of claim 13, wherein the hydroxamic acid is selected from the group consisting of unsubstituted hydroxamic acid, methylhydroxamic acid, tetrahydroxamic acid, hexylhydroxamic acid, octylhydroxamic acid, cyclohexylhydroxamic acid, octadecylhydroxamic acid, dodecylhydroxamic acid, and combinations thereof.

16. 14. The method of claim 13, wherein the hydroxamic acid further comprises a reactive group selected from the group consisting of an alkene, an alkyne, a glycidyl group, and combinations thereof.

17. The crosslinked regions of the monolayer are ２ Plasma, N ２ Plasma, NH ３ 14. The method of claim 13, wherein the negative EUV mask is removed using a reducing agent selected from the group consisting of a plasma, a fluorine-containing compound, and a combination thereof.

18. 14. The method of claim 13, wherein the negative EUV mask is augmented with a compound selected from the group consisting of phosphonic acid, phosphonic acid derivatives, stearic acid, stearic acid derivatives, and combinations thereof.

19. 14. The method of claim 13, wherein the EUV absorbing material is selected from the group consisting of platinum, tellurium, zinc, titanium, antimony, indium, bismuth, silver, and combinations thereof.

20. 1. A method for fabricating a positive extreme ultraviolet (EUV) mask, comprising: depositing a silane on a substrate, wherein the silane has a reactive head and a non-reactive tail, the silane self-aligning to form a monolayer by reaction of the head with the top surface of the substrate; patternwise exposing the monolayer to electron beam or EUV radiation, wherein the e-beam or EUV radiation activates the tails of the silane by generating polar groups on the tails of the silane only in the areas of the monolayer exposed to the e-beam or EUV radiation; and depositing an EUV absorbing material onto the treated monolayer, wherein the EUV absorbing material bonds with the polar groups of the silane tails to form a positive EUV mask. A method comprising:

21. 21. The method of claim 20, wherein the silane is selected from the group consisting of aminosilanes, ethoxysilanes, chlorosilanes, glycidoxysilanes, methacryloxysilanes, methoxysilanes, N-alkylsilanes, mercaptosilanes, and combinations thereof.

22. 1. A method for fabricating a positive extreme ultraviolet (EUV) mask, comprising: depositing a photoacid generator (PAG) on a substrate, wherein the PAG has a reactive head group and a non-reactive tail group, and the PAG self-aligns to form a polymer brush monolayer upon reaction of the head group with the top surface of the substrate; patternwise exposing the PAG to EUV radiation, wherein the EUV radiation activates the tails of the PAG by generating polar acids in the tails of the PAG only in the areas of the polymer brush monolayer exposed to the EUV radiation; and depositing an EUV absorbing material onto the treated polymer brush monolayer, wherein the EUV absorbing material bonds with the polar acid of the PAG tail to form a positive tone EUV mask. A method comprising:

23. 23. The method of claim 22, wherein the PAG is an ionic PAG selected from the group consisting of diaryliodonium salts, triarylsulfonium salts, naphthalimide sulfonic acids, and combinations thereof.

24. 23. The method of claim 22, wherein the PAG is a non-ionic PAG selected from the group consisting of iminosulfonic acid, imidosulfonic acid, benzylsulfonic acid, and combinations thereof.

25. 23. The method of claim 22, wherein the EUV absorbing material is selected from the group consisting of platinum, tellurium, zinc, titanium, antimony, indium, bismuth, silver, and combinations thereof.

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