Multi-patterning using an organometallic photo-patternable layer by an intermediate freezing process

Abstract

A multi-patterning approach using radiation-sensitive organometallic materials is described. In particular, the multi-patterning approach can be used to apply multiple different patterns of organometallic materials onto a hard mask or other substrate through a sequential approach leading to a final pattern. The multi-patterning approach can advance multiple organometallic layers through successive lithography steps, which may involve a hard bake freeze after each pattern development. The use of organometallic resists with dual-tone properties is described for cutting patterns and multiple patterning of a single organometallic layer. Corresponding structures are also described.

Description

Technical Field

[0001] Cross - Reference to Related Applications This application claims priority to U.S. Provisional Patent Application No. 63 / 020,778, filed May 6, 2020, by Stowers et al., entitled "Multiple Patterning With Organometallic Photopatternable Layers With Intermediate Freeze Steps", which is hereby incorporated by reference herein in its entirety.

[0002] This application relates to a multi - patterning approach based on organometallic photo - patterning materials that enables the use of high etching contrast. The invention further relates to structures achievable using multi - layer patterning with organometallic radiation - patterning resists.

Background Art

[0003] To continue to reduce the size of devices manufactured by lithography, photolithography systems using extreme ultraviolet light with a very short wavelength, which can enable the formation of very small images, have been developed. Organometallic coatings have been shown to be useful as photoresist materials suitable for achieving high - resolution patterning and are very promising for commercial use not only for electron - beam patterning but also for patterning using extreme ultraviolet light. To fully utilize organometallic resists, practical improvements in processing in a commercial environment can make it possible to maximize the potential of these materials.

[0004] For the fabrication of integrated devices having high-density and high-resolution features, multi-patterning methods are increasingly being used. Generally, the performance of integrated circuits is improved by reducing device size and increasing device density. Therefore, it is desirable to reduce the size of the printed features that define individual devices and increase the associated feature density. However, as the desired patterned features become smaller and approach the resolution limits of a given exposure source such as extreme ultraviolet (EUV), it becomes increasingly difficult to resolve the features with sufficient accuracy and fidelity. SUMMARY OF THE INVENTION MEANS FOR SOLVING THE PROBLEM

[0005] The invention described herein relates to multi-patterning approaches using organometallic photo-patternable materials and to structures achievable using these approaches.

[0006] In a first aspect, the invention is a method of patterning a substrate, comprising irradiating a layer of a photosensitive composition over a patterned substructure to form a latent image, wherein the photosensitive composition comprises an organometallic composition having a radiation-sensitive ligand bonded to a metal, the patterned substructure comprises, in order, a substrate, an unpatterned hard mask layer on the substrate, and a patterned metal oxide-based material having a first pattern on the hard mask layer, the photosensitive composition is located on the hard mask layer with the patterned metal oxide-based material, the pattern corresponding to the latent image is different from the first pattern, and the hard mask layer has differential etching with respect to the irradiated photosensitive composition and the patterned metal oxide-based material; and developing the latent image to form a second pattern from the irradiated photosensitive composition to form a developed structure.

[0007] In a further aspect, the present invention relates to a structure comprising a substrate, an unpatterned hard mask coating on the substrate, a first pattern of a first tin oxide-based material on the hard mask coating, wherein the gaps of the first pattern do not cover the hard mask, a second pattern of a second tin oxide-based material on the hard mask coating including the first pattern, provided that the second pattern does not overlap with the first pattern, the second pattern being different from the first pattern, and the line width roughness of the first pattern being less than 1 / 4 of the feature pitch of the first pattern.

[0008] In an additional aspect, the present invention relates to a method of forming a patterned structure using radiation-based lithography, comprising performing a positive development process on a latent image formed in a patterning composition, such as an organometallic patterning composition, deposited on a patterned metal composition supported by the structure, wherein the positive development process removes the irradiated portion of the latent image in the organometallic patterning composition and the exposed portion of the patterned metal composition to form a cut pattern in the patterned metal composition.

[0009] In another aspect, the present invention relates to a method of forming a patterned structure, comprising irradiating a structure including a layer of an organometallic radiation-sensitive material and a substrate according to a first pattern to form a first latent image; further irradiating the structure including the first latent image according to a second pattern to form a second latent image overlapping the first latent image, wherein the first latent image and the overlapping second latent image form a composite latent image; and developing the structure including the composite latent image to form a patterned structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0010]

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DETAILED DESCRIPTION OF THE INVENTION

[0011] The properties of organometallic radiation-sensitive resist compositions are utilized for advantageous multi-patterning processes that form desired structures including multiple patterns. In some embodiments, a hard mask layer between the resist composition and the substrate provides more effective pattern transfer and enables various substrate compositions. In particular, organometallic radiation-sensitive resists with high etch contrast that can be cured to form metal oxide-based compositions with increasing oxidation degree based on process conditions have been developed. Using this organometallic resist, high-resolution patterns can be formed. After the first pattern is formed, the patterned structure can be heated to further dehydrate the resist and perform a freezing process, such as forming a more oxidized composition structurally close to a metal oxide or a metal oxide composition. In alternative embodiments, the freezing process is not performed after the first patterning step to facilitate cutting of the first pattern in the second patterning step. In some embodiments, it is desirable for the frozen structure to be stable against deposition and patterning of another layer of the organometallic resist composition. Following deposition of a further layer of the resist composition, the second layer is patterned again through radiation exposure and development. In additional embodiments, a single resist layer is exposed through multiple masks, and then a single development step is performed to develop the latent images formed through the multiple masks. The organometallic resist can be effectively used for forming high-resolution patterns and can be effective for EUV patterning. Suitable resists can be used for both negative and positive patterning to efficiently enable more multi-patterning options using the same composition for predictable and reproducible multi-patterning, but the resist composition can be adjusted to optimize subsequent patterning steps. Post-treatment or intermittent treatment can be performed to improve pattern quality.

[0012] Multi-patterning techniques can be used to improve pattern resolution and extend the practical patterning capabilities achievable with a particular patterning system. For the first pattern, various features can be formed, which may be on a regular pattern such as a stripe pattern. The second pattern can overlap with the first pattern, be located within the first pattern, or be a combination of overlap with and within the first pattern. Alternatively, the second pattern can be used to cut the first pattern. Successive patterning steps perform the formation of structures that are generally not easily formed in a single patterning step, achieving higher resolution or more complexly arranged features. If desired, a third or more patterning steps may be performed. At a practical level, there is a limit to the number of successive patterning steps to provide clearly defined and properly developed features, but multi-patterning can generally involve two, three, four, five, six, seven or more patterning steps for a single layer of hard mask on a substrate, as the number of useful patterns can be extended by creative mask formation.

[0013] Furthermore, the compatible positive patterning can provide a cutting process as a multiple patterning process, and the one or more cutting processes using positive patterning can be performed after one negative patterning process or a plurality of consecutive negative patterning processes, or can be inserted as a cutting process between one or more first negative patterning processes and one or more subsequent negative patterning processes. Positive patterning as a cutting process can be performed using an organic photoresist such as an organometallic patterning composition or a chemically amplified resist, as will be described later. Using the high development contrast of the organometallic patterning composition, multiple patterning can be performed using two or more exposure processes using different masks, followed by a development process of a latent image formed from the multiple exposures. Such multiple patterning in the form of development following multiple exposures can be combined with further negative patterning processes and positive cutting processes, as described in this specification.

[0014] The formation of integrated electronic devices and the like generally involves patterning of materials for forming individual elements or components within the structure. This patterning can involve different compositions covering selected portions of stacked layers that are in contact with each other in the vertical and / or horizontal directions to introduce the desired functionality. Various materials can constitute semiconductors that can have selected dopants, dielectrics, conductors, and / or other types of materials. To form the final components such as integrated circuits, generally many layers are formed and patterned to form a final structure having different materials at positions defined by both the position within the stack and the position along the substrate.

[0015] To form a high-resolution pattern, a pattern can be introduced using a radiation-sensitive organic composition, and a part of the composition is processed to be resistant to development / etching so that a selected pattern can be introduced using selective material removal, and thus the composition can be called a resist. By using irradiation with a selected pattern or the negative of a pattern, the resist can be exposed to form a pattern or latent image having a developer-resistant region and a developer-soluble region. The radiation-sensitive organometallic composition described herein can be used for the direct formation of a desired inorganic material structure in a device and / or as a radiation-patternable organometallic resist. In either case, significant process improvements can be utilized, and the structure of the metal oxide-based material to be patterned can also be improved.

[0016] Several multi-patterning methods such as spacer-assisted double patterning (SADP) and spacer-assisted quadruple patterning (SAQP) are known in the art, but these approaches typically require multiple processing steps, which can increase manufacturing costs and make the patterning prone to defects. Therefore, a patterning approach that can improve patterning performance without significantly increasing the complexity of the process is desirable. An efficient multi-patterning approach that utilizes the high etch contrast obtained with next-generation resist materials is described herein. Hereinafter, a more efficient patterning approach enabled by using next-generation patterning-capable materials is contrasted with conventional multi-patterning approaches.

[0017] In particular, organometallic photoresists such as metal hydroxide compositions having a radiation-sensitive ligand enable a method of performing a multi-patterning process by using a freezing process such as a thermal freezing process for suitable embodiments. In the freezing process, a first photoresist layer is deposited, exposed, and developed to form a first pattern. Next, the first pattern undergoes a process to "freeze" the pattern, and a suitable freezing process can be exposure to blanket UV light and / or a thermal bake process. After forming the first pattern, a second layer of photoresist can be deposited, exposed, and developed to result in a second pattern. By combining two or more photoresist freezing processes, a selected pattern such as a cumbersome process like spacer alignment multi-patterning (SAMP), or other processes that require one or more intermediate etching processes or deposition processes can be achieved.

[0018] The metal hydroxide composition can exhibit either positive or negative patterning behavior. In negative patterning, upon exposure to radiation, the irradiated coating material is converted into a material that is more resistant to removal using a developer composition compared to the non-irradiated coating material. In positive patterning, the polarity of the exposed coating material is sufficiently changed by exposure, for example, to increase the polarity, so that the exposed coating material can be selectively removed with an aqueous solvent or other highly polar solvent. By selectively removing at least a portion of the coating material, a pattern remains with multiple regions removed to expose the underlying substrate.

[0019] Negative patterning is particularly desirable for the lower layer in a multi-patterning process because the first patterned and developed layer is not significantly affected by further irradiation in subsequent patterning steps. When the pattern of the lower layer is a positive resist, this resist can be further changed by subsequent irradiation steps. Therefore, if the positive pattern of the lower layer is not protected by a hard mask or the like during the development of the upper layer, the lower layer pattern can be damaged in the subsequent development process. Therefore, an organometallic resist that can be used for negative patterning with a small feature size is particularly suitable for multi-patterning with fewer process steps. From the viewpoint that a positive development process using an organometallic patterning composition can be used in subsequent patterning steps, it enables the cutting of the previously formed pattern and provides further process advantages for the organometallic patterning composition for the multi-patterning process.

[0020] A suitable photoresist can be based on a metal oxide chemical (metal oxo / hydroxo composition) using a radiation-sensitive ligand to control the stability and processability of the resist. Generally, these resist compositions function as negative photoresists when developed with an organic solvent. A suitable resist composition can have a peroxo ligand to impart radiation sensitivity. Peroxo-based resist compounds are described in U.S. Patent No. 8,415,000B2, entitled "Patterned Inorganic Layers, Radiation Based Patterning Compositions and Corresponding Methods" by Stowers et al., and U.S. Patent No. 8,703,386B2, entitled "Metal Peroxo Compounds With Organic Co-ligand for Electron Beam, Deep UV and Extreme UV Photoresist Applications" by Bass et al., both of which are incorporated herein by reference. Tin compositions are exemplified herein, and the data presented herein focus on tin-based resists, but the processing approaches and developer compositions described herein can be expected to be effective for other metal-based resists such as those described above and below.

[0021] Organometallic photoresists such as organotin oxide hydroxides have been shown to have excellent properties as photoresists for use in lithographic optical patterning. Suitable organometallic photoresists include those described in U.S. Patent No. 9,310,684B2 entitled "Organometallic Solution Based High Resolution Patterning Compositions" by Meyers et al., U.S. Patent No. 10,642,153 entitled "Organometallic Solution Based High Resolution Patterning Compositions and Corresponding Methods" by Meyers et al., and U.S. Patent No. 10,228,618B2 entitled "Organotin Oxide Hydroxide Patterning Compositions, Precursors, and Patterning", all of which are incorporated herein by reference. Other organometallic patterning compositions based on various metals are described in U.S. Patent Application Publication No. 2002 / 0076495 entitled "Method of Making Electronic Material" by Maloney et al. and U.S. Patent No. 9,372,402B2 entitled "Molecular Organometallic Resists for EUV" by Freedman et al., both of which are incorporated herein by reference. Resists having metal oxide nanoparticles encapsulated in an organic shell coating are described in U.S. Patent Application Publication No. 2015 / 0234272A1 entitled "Metal Oxide Nanoparticles and Photoresist Compositions" by Sarma et al., which is incorporated herein by reference. The applicant has developed highly advanced organotin patterning materials, some of which are the exemplified compositions.

[0022] Suitable organotin materials have the formula R z SnO (2-(z / 2)-(x / 2)) (OH) x(where 0 < z ≦ 2 and 0 < (z + x) ≦ 4, and R is a hydrocarbyl group having 1 to 31 carbon atoms, or for N different compositions, R N and those blends containing different R groups that can be written as) may be based on the chemical properties of the radiation-sensitive patterning composition represented thereby. In the coating layer, the composition can be incorporated into a common oxo / hydroxone network. R forms a carbon-tin bond and R can contain heteroatoms other than carbon or hydrogen. In particular, branched alkyl ligands are such that the compound is R 1 R 2 R 3 CSnO (2-(z / 2)-(x / 2)) (OH) x (where R 1 and R 2 are independently alkyl groups having 1 to 10 carbon atoms, and R 3 is hydrogen, or an alkyl group having 1 to 10 carbon atoms) would be desirable for some patterning compositions that can generally be represented as. As will be described later, this representation of the alkyl ligand R generally applies equally to other embodiments using R 1 R 2 R 3 CSn(X)3, where X corresponds to a hydrolyzable ligand such as an alkoxide or amide moiety. In some embodiments, R 1 and R 2 can form a cyclic alkyl moiety, and R 3 can also bond to other groups in the cyclic moiety. Suitable branched alkyl ligands are, for example, isopropyl (R 1 and R 2 are methyl, and R 3 is hydrogen), tert-butyl (R 1 , R 2 and R 3 are methyl), tert-amyl (R 1 and R 2 are methyl, and R 3 is -CH2CH3), sec-butyl (R 1 is methyl, R 2 is -CH2CH3, and R 3is hydrogen), neopentyl (R 1 and R 2 is hydrogen and R 3 is -C(CH3)3), cyclohexyl, cyclopentyl, cyclobutyl, and cyclopropyl). Examples of suitable cyclic groups include, for example, 1-adamantyl (-C(CH2)3(CH)3(CH2)3 or tricyclo(3.3.1.13,7)decane bonded to the metal at a tertiary carbon) and 2-adamantyl (-CH(CH)2(CH2)4(CH)2(CH2) or tricyclo(3.3.1.13,7)decane bonded to the metal at a secondary carbon)). In other embodiments, the hydrocarbyl group can include an aryl or alkenyl group, such as benzyl or allyl, or an alkynyl group. In other embodiments, the hydrocarbyl ligand R can consist of only C and H and can include any group containing 1 to 31 carbon atoms. In summary, some examples of suitable alkyl groups bonded to tin include, for example, linear or branched alkyl (i-Pr ((CH3)2CH-), t-Bu ((CH3)3C-), Me (CH3-), n-Bu (CH3CH2CH2CH2-)), cycloalkyl (cyclopropyl, cyclobutyl, cyclopentyl), olefin (alkenyl, aryl, allyl), or alkynyl group, or combinations thereof. In a further embodiment, suitable R groups can include hydrocarbyl groups substituted with a heteroatom functional group containing cyano, thio, silyl, ether, keto, ester, or halogenated group, or combinations thereof. As is conventional in the art, a hydrocarbyl group can be referred to as an alkyl group even though the group can have unsaturated bonds, aryl groups, heteroatoms, etc., and thus, a monoalkyl compound / composition refers to a compound / composition where z = 1.

[0023] The precursor composition can be employed to form an organotin oxo / hydroxo coating composition incorporated into a common oxo / hydroxo network. The precursor composition can include one or more soluble organotin oxo / hydroxo compounds or corresponding compounds having hydrolyzable ligands that form oxo and / or hydroxo ligands upon hydrolysis. In the case of a precursor composition containing a plurality of compounds, the compounds can have different organic ligands having metal-carbon bonds and the same or different hydrolyzable ligands. Thus, the precursor composition for forming a radiation-sensitive coating is R N SnX 4-n (wherein n = 1, 2, or 3, R is a hydrocarbyl group having 1 to 31 carbon atoms as described above, and X is a ligand having a hydrolyzable M-X bond) and can include a solution of one or more compounds represented thereby and mixtures thereof. Suitable hydrolyzable ligands include, for example, alkynide (R 0 C≡C-), alkoxide (R 0 O-), carboxylate (R 0 COO-), halide, dialkylamide, or combinations thereof, where the R 0 group can be one of the same moieties described above for R. In particular, an organotin trialkoxide composition can be represented by the formula RSn(OR 0 )3. Also, an organotin tridialkylamide composition can be represented by the formula RSn(NR a R b )3 (wherein the R a group and the R b group can be one of the same moieties described above for R). In some embodiments, the above-described organotin precursor composition can further include a composition represented by MX4 and / or MO ((m / 2)-l / 2) (OH) l (wherein 0 < z ≦ 2, 0 < (z + w) ≦ 4, m is the formal valence of M m+ , 0 ≦ l ≦ m, and M = M’ or Sn, where M’ is a non-tin metal of Groups 2 to 16 of the periodic table).

[0024] Generally, organotin photoresists exhibit both high resolution and high etch resistance, enabling the formation of small features and patterns. During or after the coating process, in situ hydrolysis can be used to hydrolyze any hydrolyzable M-X bond to form an oxo / hydroxy network in the pre-patterning coating. The precursor compounds can further form clusters in solution with appropriate ligand rearrangement, where at least a portion of the hydrolyzable ligands are substituted with oxo bridges or hydroxyl groups, such as may be substituted with three tin atoms, as described in both U.S. Patent Application Publication No. 2019 / 0053001, entitled "Organotin Clusters, Solutions of Organotin Clusters, and Application to High Resolution Patterning" by Cardineau et al., and U.S. Patent Application Publication No. 2019 / 0308998, entitled "Tin Dodecamers and Radiation Patternable Coatings With Strong EUV Absorption" by Cardineau et al., both of which are incorporated herein by reference.

[0025] The above-described compositions can be used to form a layer of coating material via various means known to those skilled in the art and post-treatment of the precursor onto a selected structure. Generally, the structure comprises a substrate having a hard mask coating on its surface. The hard mask surface provides patterning uniformity while undergoing a multi-patterning process that is performed to reduce the size of the pattern features. The hard mask layer can include a material having good etching contrast with the resist to be patterned. In some embodiments, the hard mask is designed to be ultimately removed, while in some embodiments, the patterned portions of the hard mask must be maintained for later processing. The selection of the hard mask can be based on its compatibility with the material under the hard mask in a substrate that can itself be patterned with different materials and, optionally, the etching contrast.

[0026] The multi-patterning with the organometallic resists described herein provides significant flexibility to efficiently provide high-resolution patterning based on high development contrast and good radiation absorption. Various embodiments of multi-patterning can be effectively utilized to form various final desired patterns. The use of tin-based organometallic patterning compositions, improved developers, and post-development pattern quality improvement can be utilized to reduce pattern imperfections.

[0027] Coating Characteristics and Coating Formation The deposition process for forming a radiation-patternable layer can be solution-based or vapor-based. The substrate generally presents a surface on which a coating material can be deposited, and the substrate can include multiple layers. In some embodiments, the substrate surface may be treated to prepare the surface for the adhesion of the coating material. Further, the surface can be washed and / or smoothed as appropriate. A suitable substrate surface can include any suitable material. Some particularly interesting substrates include, for example, silicon wafers, silica substrates, other inorganic materials, polymer substrates such as organic polymers, composites thereof, and combinations thereof on the entire surface and / or layers of the substrate. Wafers such as relatively thin cylindrical structures can be convenient, but structures of any suitable shape can be used. Substrates having a polymer layer on a polymer substrate or a non-polymer structure are desirable for certain applications based on their low cost and flexibility, and suitable polymers can be selected based on the relatively low processing temperatures that can be used for the treatment of the patternable materials described herein. Suitable polymers can include, for example, polycarbonate, polyimide, polyester, polyalkene, copolymers thereof, and mixtures thereof.

[0028] In some embodiments, the hard mask layer is formed on the substrate prior to the deposition of the radiation-patternable coating. The hard mask layer can have an average thickness of from about 1 nm to about 200 nm, in further embodiments from about 2 nm to about 150 nm, in other embodiments from about 2.5 nm to about 100 nm, and in additional embodiments from about 3 nm to about 75 nm. One of ordinary skill in the art will recognize that other ranges within the explicitly stated average thickness ranges above are also contemplated and that those ranges are also within the scope of the present disclosure. For the purpose of achieving a desired pattern on a desired substrate (such as silicon), the desired hard mask material can typically be selected based on its etching characteristics with respect to other layers. Generally, the hard mask material is selected based on its etching "color" and is deposited in a film stack, where "color" refers to the etching sensitivity to a particular etching chemistry.

[0029] Examples of materials suitable for the hard mask layer include, for example, titanium nitride (TiN), silicon nitride (Si3N4), tantalum nitride (TaN), silicon oxide (SiO2, spin-on glass, silicon oxynitride), carbon-rich materials (e.g., spin-coated carbon (SOC), CVD carbon layer), etc., but various other materials may also be suitable. Regarding differential etching, for example, silicon oxide type materials have an etching rate measurable in F-containing plasmas, while carbon-rich materials do not. Similarly, carbon-rich materials can be easily etched by O-containing plasmas, while silicon oxide is resistant. TiN can be etched by Cl-containing plasmas, while SiO2 is resistant. Different final patterns can suggest different etch stacks. For example, a complex logic pattern having many lines, spaces, and rectangular features may be patterned using a different film stack than a memory pattern consisting of an array of dots or holes. The holes can be substantially circular, rectangular, square, or other suitable shapes. Based on the teachings herein, the selection of appropriate hard mask materials, stack configurations, etching chemistries, and their relative etching differences are known to those skilled in the art and are within the scope of the present disclosure.

[0030] The hard mask can be deposited using a vapor deposition method such as chemical vapor deposition (CVD), physical vapor deposition (PVD), or atomic layer deposition (ALD), or a solution-based coating method such as spin-on glass or spin-on carbon. Spin-on carbon (SoC) generally refers to a composition with a high carbon content that can be deposited as a liquid and generally contains, for example, a high-carbon content polymer or molecules such as fullerenes, which are commercially available as spin-on carbon from Irresistible Materials, Ltd in the UK. Spin-on glass materials are commercially available, for example, from Desert Silicon (Arizona, USA). The spin-on glass composition contains a polysilazane polymer in a suitable organic solvent such as an ether or aromatic solvent, and the polysilazane polymer can be cured in an oxygen atmosphere to form silicon oxide. The polysilazane composition for spin-on glass is described in U.S. Patent No. 7,270,886 to Lee et al., entitled "Spin-On Glass Composition and Method of Forming Silicon Oxide Layer Semiconductor Manufacturing Process Using the Same", which is incorporated herein by reference. The spin-on glass formulation containing polyorganosiloxane is described in U.S. Patent No. 5,302,198 to Allman, entitled "Coating Solution for Forming Glassy Layers", which is incorporated herein by reference. Suitable silica-based sol-gel compositions are known in the art and can be used as spin-on glass compositions. For example, the sol-gel composition for forming a silica glass material is described in U.S. Patent Application Publication No. 2002 / 0157418 to Ganguli et al., entitled "Process for Reducing or Eliminating Bubble Defects in Sol-Gel Silica Glass", which is incorporated herein by reference. The spin-on glass composition can be thermally cured in an oxygen-containing atmosphere to form quartz glass.Silica glass is generally deposited in various contexts using chemical vapor deposition (CVD) or other processes known in the art.

[0031] Furthermore, a suitable substrate can include a pre-formed organometallic photoresist pattern. Additionally, the substrate can include pre-patterned structures as described in U.S. Patent No. 10,649,328 to Stowers et al., entitled "Pre-Patterned Lithography Templates, Processes Based on Radiation Patterning Using the Templates and Processes To Form the Templates", and U.S. Patent No. 9,005,875 to Bristol et al., entitled "Pre-Patterned Hardmask for Ultrafast Lithographic Imaging", both of which are incorporated herein by reference. Generally, the substrate can comprise a plurality of layers of different or partially different compositions, where each layer can be patterned components or portions of components that may be integrated with additional components or portions of components based on further lithography processes for patterning additional layers on and / or within the substrate.

[0032] Examples of suitable deposition methods for the organometallic resist include solution processing methods such as spin coating or dip coating, or vapor deposition methods such as atomic layer deposition (ALD), physical vapor deposition (PVD), or chemical vapor deposition (CVD) processes, which can be used to form the organometallic coating. If solution processing is desired, the organotin composition is desirably dissolved in a solvent to assist the vapor deposition process. Generally, the desired organotin composition can be dissolved in an organic solvent, such as alcohols, aromatic and aliphatic hydrocarbons, esters, or combinations thereof. In particular, suitable solvents include, for example, aromatic compounds (e.g., xylene, toluene), ethers (anisole, tetrahydrofuran), esters (propylene glycol monomethyl ether acetate, ethyl acetate, ethyl lactate), alcohols (e.g., 4-methyl-2-propanol, 1-butanol, methanol, isopropyl alcohol, 1-propanol), ketones (e.g., methyl ethyl ketone), mixtures thereof, and the like. Generally, the choice of organic solvent can be affected by solubility parameters, volatility, flammability, toxicity, viscosity, and potential chemical interactions with other processing materials. After the components of the solution are dissolved and mixed, the nature of the species can change as a result of partial in-situ hydrolysis, hydration, and / or condensation in some embodiments. When referring to the composition of the solution herein, this reference is to the components when added to the solution, as solvolysis and ligand metathesis may occur in complex formulations or metal polynuclear species may be formed in solutions that may not be fully characterized. For certain applications, it is desirable for the organic solvent to have a flash point of about 10 °C or higher, in further embodiments about 20 °C or higher, in further embodiments about 25 °C or higher, and a vapor pressure at 20 °C of about 10 kPa or lower, in some embodiments about 8 kPa or lower, in further embodiments about 6 kPa or lower. One of ordinary skill in the art will recognize that other ranges of flash point and vapor pressure within the above explicit ranges are also contemplated and are within the scope of this disclosure.

[0033] In some embodiments, the vapor deposition method may involve reacting one or more metal-containing precursors with low molecular weight gas-phase reagents such as H2O, H2O2, O3, O2, CO2, CO, or CH3OH that function as sources of O and H for the formation of oxides and oxyhydroxides, or together with them. In the CVD method, generally two or more reaction gases are mixed in the chamber near the substrate surface. Therefore, in order to suppress unwanted gas-phase reactions and nucleation, the reaction conditions can be designed to be sufficiently stable. The ALD precursors sequentially introduced individually into the reaction chamber typically react with chemisorbed co-precursors or decomposition products to saturate the substrate surface. R N SnX (4-n) Desirable characteristics of the precursors include, for example, sufficient volatility in the gas-phase transport within the system, thermal stability to prevent premature decomposition, and / or appropriate reactivity with co-precursors to produce the target product under given process conditions. The pressure and temperature in the reaction chamber can be selected to control the reaction process. Generally, precursors with relatively low vapor pressures can be introduced using vapor flow to the evaporation chamber, aerosol, and / or direct liquid injection. A flash evaporator can be used to introduce a controlled amount of precursor vapor into the reaction chamber and correspondingly control the reaction process within the chamber. The secondary reactant for promoting hydrolysis / oxidation can be introduced into the chamber from a separate inlet. It is also possible to adapt a commercially available CVD apparatus for this use or to use specific equipment. To facilitate deposition, the substrate may be heated or cooled depending on the characteristics of the precursor. Inert gases such as N2, Ar, etc. can be used in both the sequential flow regime and the continuous flow regime in an appropriate volume as carrier gas, purge gas, or pressure regulating gas.

[0034] When the vapor deposition method is desired, the organotin precursor can be selected for desired properties such as volatility and reactivity, which are susceptible to deposition, by the choice of radiation-sensitive ligands (alkyl groups) and hydrolysis-sensitive and / or oxidizing ligands. Examples of suitable compositions are the same as those described above for the formation of organotin solutions. For example, the precursor composition for forming a radiation-sensitive coating is RN SnX 4-n (wherein n = 1, 2, or 3; R is a hydrocarbyl group having 1 to 31 carbon atoms as described above; and X is an oxidizing ligand and / or a ligand having a hydrolyzable M-X bond), and one or more compounds represented thereby and mixtures thereof can be included. The vapor phase growth process can be controlled to provide a desired coating thickness.

[0035] In solution-based deposition, the thickness of the coating can generally be a function of process parameters such as the concentration, viscosity, and spin rate of the precursor solution. In other coating processes such as vapor phase growth, the thickness can generally also be adjusted through the selection of deposition and coating parameters such as flow rate, cycle time, number of cycles, etc. In some embodiments, it may be desirable to use a thin coating to facilitate the formation of small and high-resolution features.

[0036] In some embodiments, the coating material can have an average dry thickness before development of about 1 micron or less, in further embodiments about 250 nanometers (nm) or less, in additional embodiments about 1 nanometer (nm) to about 100 nm, in further embodiments about 1 nm to about 50 nm, in other embodiments about 1 nm to about 40 nm, and in some embodiments about 1 nm to about 25 nm. The range of the coating thickness after development relative to the exposed area generally falls within the same range presented above, based on the recognition that development can remove a relatively small amount of the exposed material. Generally, in a multi-patterning process, each coating layer of the radiation-patternable composition can fall within these dry thickness ranges. In a multi-patterning process, subsequent radiation-patternable coatings can have the same average thickness or a different average thickness relative to the previous radiation-patternable coating. Those skilled in the art will recognize that other ranges of solution concentration and thickness within the explicit ranges above are also contemplated and that such ranges are also within the scope of the present disclosure. The thickness can be evaluated using non-contact methods of X-ray reflectivity and / or polarization analysis based on the optical properties of the film. For a radiation-patternable layer following a previously patterned layer, the average thickness is evaluated relative to the existing patterned surface extending upward from the surface with respect to the plane of the structure, recognizing that the subsequent layer may not be generally flat.

[0037] For multi-patterning using a positive resist to cut an initial pattern, the positive resist can effectively be an organometallic photoresist, such as the same or a similar resist used for the first negative patterning, or an organic positive resist, such as a DNQ-novolac resin which is a blend of diazonaphthoquinone (DNQ) and a novolak resin (phenol formaldehyde resin). Commercially available formulations of these positive resists are available, for example, from Fujifilm Holdings America Corp.

[0038] After the deposition and formation of an organotin coating or other organometallic coating, an edge bead removal (EBR) rinse process can generally be used. The EBR process is typically performed after the deposition of the photoresist and before any heat treatment or bake, and involves rinsing the peripheral edges of the wafer or substrate with a solvent to remove the photoresist in the selected areas. EBR and backside rinsing involve applying an edge bead rinse solution not only to the backside but also to the edges of the wafer, as described in U.S. Patent No. 10,627,719 to Waller et al., which is incorporated herein by reference.

[0039] Soft bake or post-apply bake (PAB) is typically performed before radiation exposure to hydrolyze the hydrolyzable bonds in the precursor composition and / or further remove the solvent to promote densification of the coating material. In some embodiments, PAB can be performed at a temperature of about 25°C to about 250°C, in additional embodiments about 50°C to about 200°C, and in further embodiments about 80°C to about 150°C. Post-exposure heating can generally be performed for at least about 0.1 minutes, in further embodiments about 0.5 minutes to about 30 minutes, and in additional embodiments about 0.75 minutes to about 10 minutes. Those skilled in the art will recognize that other ranges of PAB temperature and time within the above explicit ranges are also contemplated and that such ranges are also within the scope of the present disclosure. In particularly interesting embodiments, the material being coated generally comprises a polymeric metal oxo-hydroxido network based on the bonding of oxo-hydroxido ligands to a metal that also has some organic (hydrocarbyl) ligands, or a molecular solid composed of polynuclear metal oxo-hydroxido species having organic (hydrocarbyl) ligands.

[0040] Patterning and Development Generally, a selected organometallic photoresist coating can be patterned using radiation. Suitable radiation sources include extreme ultraviolet (EUV), ultraviolet (UV), or electron beam (EB) radiation. In the manufacture of semiconductor devices, EUV radiation would be desirable as it has higher resolution compared to UV radiation and higher throughput compared to electron beam (EB)-based processes. The radiation can generally be directed at the substrate through a mask or scanned across the substrate while controlling the radiation beam to form a latent image within the resist coating. In this section, the general principles for patterning an organometallic coating to form a patterned metal oxide-based material are described, and in the next section, specific processes for multi-patterning are described.

[0041] According to the international standard ISO21348 (2007), which is incorporated herein by reference, ultraviolet light extends between wavelengths of greater than 100 nm and less than 400 nm. A krypton fluoride laser can be used as a source of 248 nm ultraviolet light. The ultraviolet range can be further subdivided in several ways under accepted standards, for example, into extreme ultraviolet (EUV) of greater than 10 nm and less than 121 nm, far ultraviolet (FUV) of greater than 122 nm and less than 200 nm, etc. The 193 nm line emitted from an argon fluoride laser can be used as a radiation source in FUV. EUV light is used in lithography at 13.5 nm, and this light is generated from a Xe or Sn plasma source excited using a high-energy laser or a discharge pulse. Commercial sources of EUV photons include scanners manufactured by ASML Holding N.V. of the Netherlands. Soft X-rays can be defined as greater than 0.1 nm and less than 10 nm. Light is directed through a mask to form a latent image within a radiation-sensitive coating that includes exposed and unexposed regions.

[0042] The amount of electromagnetic radiation can be characterized by the fluence or dose, which is obtained by integrating the radiation flux over the exposure time. In some embodiments, a suitable radiation fluence is about 1 mJ / cm 2~about 200 mJ / cm 2 、In a further embodiment, about 2 mJ / cm 2 ~about 150 mJ / cm 2 、In a further embodiment, about 3 mJ / cm 2 ~about 100 mJ / cm 2 is used. In one embodiment, the EUV radiation is performed at a dose of about 150 mJ / cm 2 or less, or with an electron beam at a dose of about 2 mC / cm 2 or less at 30 kV. Those skilled in the art will recognize that other ranges of radiation fluence within the above explicit ranges are also contemplated and are within the scope of the present disclosure.

[0043] Following exposure to radiation and formation of a latent image, a subsequent post-exposure bake (PEB) is typically performed. The timing of PEB in the context of multipatterning is described below. In some embodiments, the PEB can be performed in the ambient environment, and in additional embodiments, the PEB can be performed in the presence of reactive gases such as H2O, CO2, CO, SO2, H2 as described in U.S. Patent Application No. 17 / 188,679, titled "Process Environment For Inorganic Resist Patterning" by Telecky et al., which is incorporated herein by reference (hereinafter, the '679 application). In some embodiments, the PEB can be performed at a temperature of about 45°C to about 250°C, in additional embodiments about 50°C to about 190°C, and in further embodiments about 60°C to about 175°C. The post-exposure heating can generally be performed for at least about 0.1 minutes, in further embodiments about 0.5 minutes to about 30 minutes, and in additional embodiments about 0.75 minutes to about 10 minutes. Those skilled in the art will recognize that other ranges of PEB temperature and time within the above explicit ranges are also contemplated and are within the scope of the present disclosure. The PEB can be designed to further densify and / or strengthen the exposed regions without decomposing the unexposed regions into metal oxides.

[0044] After PEB, development of the image involves contacting the patterned coating material containing the latent image with a developer composition to remove either the unexposed coating material to form a negative image or the exposed coating to form a positive image, and other organometallic patterning materials may or may not be suitable for both types of patterning templates. Using the organotin resist materials described herein, generally based on the same coating formed from the same precursor composition, effective negative or positive patterning can be performed at a desired resolution using an appropriate developer solution, although optimization of the coating may suggest some adjustment of the composition. In particular, the irradiated regions are at least partially condensed to increase the metal oxide characteristics such that the exposed material is resistant to dissolution by an organic solvent while the unexposed composition remains soluble in the organic solvent. Reference to a condensed coating material means at least partial condensation in the sense of increasing the oxide characteristics of the material relative to the initial material. On the other hand, since the unexposed material is not soluble in a weak aqueous base or acid due to the hydrophobic nature of the material, an aqueous base can be used to remove the exposed material while maintaining the unexposed material for positive patterning.

[0045] For positive image formation, suitable developers can generally be aqueous acids or bases. In some embodiments, an aqueous base can be used to obtain a sharper image. To reduce contamination by the developer, it would be desirable to use a developer that does not have metal atoms. Thus, quaternary ammonium hydroxide compositions such as tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, or combinations thereof are desirable positive developers. Generally, particularly interesting quaternary ammonium hydroxides can be represented by the formula R4NOH, where R = methyl, ethyl, propyl, butyl, or combinations thereof. The coating materials described herein can generally be developed using the same developers currently commonly used for polymer resists, specifically tetramethylammonium hydroxide (TMAH). Commercially available TMAH is available at 2.38 wt%. Additionally, mixed quaternary tetraalkylammonium hydroxides can be used. Generally, the developer can contain from about 0.5 to about 30 wt%, in further embodiments from about 1 to about 25 wt%, and in other embodiments from about 1.25 to about 20 wt% of tetraalkylammonium hydroxide or a similar quaternary ammonium hydroxide. Those skilled in the art will recognize that other ranges of developer concentrations within the above explicit ranges are also contemplated and that those ranges are also within the scope of this disclosure.

[0046] In the case of negative imaging, the developer can be an organic solvent such as a solvent used to form the precursor solution. Generally, the choice of developer can be affected by solubility parameters regarding both irradiated and non-irradiated coating materials, as well as the volatility, flammability, toxicity, viscosity, and potential chemical interactions with other process materials of the developer. In particular, suitable developers include, for example, aromatic compounds (e.g., benzene, xylene, toluene), esters (e.g., propylene glycol monomethyl ether acetate (PGMEA), ethyl acetate, ethyl lactate, n-butyl acetate, butyrolactone), alcohols (e.g., 4-methyl-2-pentanol, 1-butanol, isopropanol, 1-propanol, methanol), ketones (e.g., methyl ethyl ketone, acetone, cyclohexanone, 2-heptanone, 2-octanone), ethers (e.g., tetrahydrofuran, dioxane, anisole), and the like. Improved developer compositions are described in U.S. Patent Application Publication No. 2020 / 0326627, entitled "Organometallic Photoresist Developer Compositions and Processing Methods" by Jiang et al., which is incorporated herein by reference. The improved developer solution generally includes a reference organic solvent composition and an additive composition having higher polarity and / or hydrogen bonding characteristics than the reference solvent composition. In one example, the improved developer composition can include PGMEA and acetic acid. Development can be carried out for about 5 seconds to about 30 minutes, in a further embodiment for about 8 seconds to about 15 minutes, and in an additional embodiment for about 10 seconds to about 10 minutes. Those skilled in the art will recognize that other ranges within the above explicit ranges are also contemplated and that such ranges are also within the scope of the present disclosure.

[0047] After development, it may be desirable to perform a freezing process such as a hard bake on the newly formed resist pattern to remove the remaining developer and improve the fidelity of the patterned lines. Such a post-development bake process can be used as a freezing process in the context of multi-patterning, as will be further explained below. Generally, the hard bake conditions can be the same as those of the PEB process. In some embodiments, the hard bake can be performed in the ambient environment, and in additional embodiments, the PEB can be performed in the presence of reactive gases such as H2O, CO2, CO, SO2, H2, etc., as described in the '679 patent application cited above. In some embodiments, the hard bake can be performed at a temperature of at least about 45°C, in some embodiments from about 45°C to about 400°C, in additional embodiments from about 50°C to about 300°C, and in further embodiments from about 60°C to about 250°C. The hard bake can generally be performed for at least about 0.1 minute, in further embodiments from about 0.5 minute to about 30 minutes, and in additional embodiments from about 0.75 minute to about 10 minutes. Those skilled in the art will recognize that other ranges of PEB temperature and time within the explicit ranges above are also conceivable and that those ranges are also within the scope of the present disclosure. In some embodiments of the multi-patterning process, it may be desirable to limit, avoid, or delay the post-development bake process in order to perform further development of the initial pattern during a subsequent patterning step.

[0048] Multi-patterning After forming an initial pattern of an organometallic material on a surface, another layer of an organometallic photoresist can be deposited on the pattern. Due to the process advantages of the organometallic patterning composition, generally, an intervening processing step for separating a subsequent patterning resist from a pre-patterned underlying layer is not used. Due to the chemical changes that occur during the exposure and / or PEB process, the existing pattern of the organometallic photoresist is insoluble in the coating composition. This property of the photoresist enables a patterning approach that would require more complex processing with conventional polymer resists known to those skilled in the art.

[0049] For example, double patterning using a conventional resist requires transferring the resist pattern to another medium, for example, by using a litho-etch-litho-etch (LELE) process or a spacer alignment patterning approach. In a typical LELE process, a first photoresist pattern is transferred to a hard mask layer that is generally not initially patterned, and then a second lithography process is performed to form a second photoresist pattern, and a second etching is performed thereon to transfer the second pattern to the hard mask. By combining two patterns with a smaller pitch, the final pattern of the hard mask can be made to have a pitch smaller than that of the original photoresist pattern. In a general spacer alignment process, such as a spacer alignment double patterning (SADP) process, a spacer material having higher etch resistance than the photoresist material is conformally deposited on the first photoresist pattern, and then a series of etchings are performed on the entire substrate to first remove a part of the spacer material so that only sidewalls remain, and then the remaining photoresist pattern is stripped to form a spacer material pattern with a pitch smaller than that of the first resist pattern. Such a process requires a plurality of processing steps to be performed, with the cost and complexity increasing in each step, and the possibility of defects also increasing.

[0050] The concept of multi-patterning in this specification generally involves successive patterning steps having selected relationships between subsequent patterns and a first pattern. These relationships are schematically illustrated in FIGS. 1A - 1E. In FIG. 1A, a second pattern is developed to form features between the features of the first pattern such that the feature pitch is effectively reduced. As shown in this figure, the patterns are stripes at regular intervals. Referring to FIG. 1B, a second pattern overlapping the first pattern intersects the first pattern and, in this particular embodiment, is orthogonal to the first pattern. Each pattern depicted in FIG. 1B is also here a series of stripes at regular intervals. Referring to FIG. 1C, a second pattern overlapping the first pattern has features oblique to the first pattern, and the features of both patterns are stripes at regular intervals. With respect to the multi-patterning structures of FIGS. 1A - 1C, the stripes may be made at irregular intervals or different shapes may be used for the stripes, within the feature size and pitch constraints of the patterning process. Referring to FIG. 1D, the second pattern has different characteristics from the first pattern, with some being here between the features of the first pattern and some overlapping the features of the first pattern.

[0051] FIG. 1E shows a cut of the first pattern using a second patterning step. The cut of the first pattern is guided by the second pattern. The cut process can be effectively performed using inverse-type patterning in each step. The second resist coating layer is completely stripped after the cut process and before further processing.

[0052] In the discussion in this specification, although the focus is mainly on two patterning processes, a third or more patterning processes may be performed sequentially. These three or more patterning processes can be regarded as a simple generalization of the multi-patterning format in FIGS. 1A to 1E. The cut process in FIG. 1E may be interposed between other multi-patterning processes or may be the last process of cutting one or more previous patterns to form a cut pattern. Dividing the entire target pattern into sequential patterns using multiple masks can be a complex procedure, and a systematic approach for dividing such masks is described, for example, in U.S. Patent No. 9,679,095 entitled "Layout Decomposition for Multiple Patterning Lithogrnphy" by Li et al. and in U.S. Patent Application Publication No. 2015 / 0040083 entitled "System and Method for Decomposition of a Single Photoresist Mask Pattern Into 3 Photoresist Mask Patterns" by Cheng et al., both of which are incorporated herein by reference.

[0053] The desirable processing approach described herein provides effective multi-patterning without pattern transfer, based on high etching contrast and optimization of pattern development. Thus, multi-patterning can be performed using fewer steps than can be used for multi-patterning with an organic resist. Generally, one or more underlying patterns are based on negative patterning. The irradiated resist is maintained and the non-irradiated resist is removed by a developer. Thereafter, subsequent layers or resists can be deposited without the solvent for the resist damaging the first pattern. After pattern development, a post-patterning freezing step, i.e., a baking step, can optionally be performed to stabilize the pattern, and such a freezing step would generally be desirable to improve the overall patterning quality after the multi-patterning process. The cut step can be performed using a positive patterning process such that the developer removes both the irradiated resist composition and the exposed portions of the previous pattern. Positive patterning for the cut can be performed using an organometallic patterning composition or an organic resist which can be a chemically amplified resist (CAR). Due to the high pattern contrast, this is a manageable operation without pattern transfer.

[0054] Thus, for the multi-patterning depicted in FIGS. 1A - 1D, a litho-freeze-litho-freeze (LFLF) process (the freezing step being optional and / or adjustable) enables a simpler processing scheme for achieving more complex, higher density, or improved patterns compared to a single patterning approach and a simpler processing scheme compared to other multi-patterning approaches available using conventional resists. In particularly interesting embodiments, the present process utilizes a hard mask on the substrate that provides higher applicability without being constrained by the substrate composition. During processing of complex structures, many layers of materials can be deposited and patterned such that the composition of the top surface of the substrate can be changed at the start of the patterning process.

[0055] Figure 2A shows a flowchart of the LFLF process. Referring to Figure 2A, to start the process, a substrate is obtained 10 and a hard mask layer is disposed on the substrate 12. Two lithography processes are shown as parallel vertical array steps. During the first lithography process, using the method described above, an organometallic photoresist is deposited on the substrate 14. The resist then undergoes patterned radiation exposure 16 and development 18 to form an image or pattern from the latent image. Optionally, the structure can be subjected to freezing 20 to enable subsequent lithography steps while reducing damage to the original developed pattern. Freezing can be performed using the post-development bake process and / or an additional unpatterned UV irradiation process described above. Post-development UV irradiation can be used to decompose the remaining carbon-metal bonds and further stabilize the material for further processing. The blanket UV irradiation process can be performed on the same tool without a mask. The subsequent lithography process can then be performed without removing the developed pattern formed in the first lithography process.

[0056] The second lithography process similarly involves depositing an organometallic photoresist on the frozen developed pattern of the first lithography process 22, irradiating the organometallic resist with radiation 24 to form a second latent image, developing the second latent image 26, and optionally performing a second hard bake freeze 28 to stabilize the second post-development pattern. More litho-freeze processes as shown in the parallel set of steps in Figure 2A may be performed until the desired pattern of the organometallic photoresist is obtained. Once patterning is complete, further processing 30 of the device can be performed. By simplifying the process to perform more than one lithography step, the device can be manufactured more efficiently.

[0057] The cutting process is similar to the lithography process of FIG. 2, except that after the cutting process, the unexposed resist is removed before any optional hard bake and further processing which may be either an additional lithography process or the next step in device formation. The cutting process is shown in FIG. 2B. After the previous patterning 32 is completed, an organometallic photoresist is deposited 34. Next, the resist layer is exposed to patterned radiation 36 and a latent image is formed. This latent image is developed 38 as a positive resist. In the cutting process, the development 38 can be effective to remove not only the irradiated resist but also the exposed areas of the underlying patterned resist formed from the irradiated resist by the previous lithography patterning process. Thus, process step 38 includes development and cutting performed simultaneously. Following the development / cutting 38, the unexposed resist is stripped 40. After the stripping 40, an optional post-patterning bake can be performed 42 to stabilize the pattern. Thereafter, additional processing can be performed 30.

[0058] A double patterning process using "freezing" is outlined in FIG. 3. The initial structure 50 includes a substrate 52 having a hard mask coating 54. The substrate 52 may or may not have an upper section 56 which can be subjected to processing and which may or may not have its own distinct composition and / or patterning. In the first stage of processing 58, a first pattern 60 is formed on the hard mask 54. This patterning stage includes several steps as outlined in FIG. 2 in relation to the first column of steps for forming the first pattern. Next, a second patterning stage is performed 62 to form a second pattern 64 on the hard mask 54. FIG. 3 depicts a second pattern within the first pattern to form an overall pattern of higher resolution, and the second pattern may be of any of the types depicted in FIGS. 1A - 1E. Additional patterning stages can be performed and, in the context of the overall process, the second pattern 64 can be considered the final pattern.

[0059] Once the second, i.e., the final pattern 64 is formed, the entire pattern can be further processed 66 by transferring the entire pattern to the hard mask 54 and stripping the remaining resist to form the patterned hard mask 68. Next, the hard mask pattern is transferred to the upper section 56 of the substrate 52. The pattern transfer to the upper section 56 can include etching 70 to form the etched substrate 72, or deposition 74 to form the patterned hard mask 68 having the deposit 76, and then hard mask etching 78 to form the patterned substrate 80.

[0060] It is easy to extend this process to multiple coating and patterning steps, and it should be noted that such extensions are contemplated and within the scope of the present disclosure. Regarding multipatterning, an important difference between the inorganic coating materials described herein and conventional organic resists is that organic resists remain soluble in conventional resist cast solvents even after a thermal bake. The resist materials described herein are not soluble in organic solvents and can be condensed by a thermal bake so that subsequent coating layers can be applied.

[0061] Some examples of useful applications of the present invention include combining two different patterns that require different lighting conditions, e.g., combining a pillar pattern and a line-space pattern. Another advantage of the present invention is that it can provide the advantage of stitching of a desired pattern, where a portion of the desired pattern is printed and then another portion of the pattern is printed to print a complete pattern that would otherwise be difficult to achieve in a single lithography process. Multiple exposure media can be further used for the present invention, using multiple exposure steps independently selected from exposure sources such as EUV, ArF, KrF, and electron beam, and combining each pattern into a new pattern that would otherwise be difficult or impossible to achieve when using only one exposure source.

[0062] In some embodiments, adjacent linear segments of adjacent structures can have an average pitch (half-pitch) of about 60 nm or less (30 nm half-pitch), in some embodiments about 50 nm or less (25 nm half-pitch), and in further embodiments about 34 nm or less (17 nm half-pitch). The pitch can be evaluated by design and confirmed by a scanning electron microscope (SEM) using, for example, an image viewed from above. As used herein, pitch refers to the spatial period of repeating structural elements, or the center-to-center distance, and half-pitch, as commonly used in the art, is half of the pitch. The dimensions of the features of the pattern may also be described in terms of the average width of the features, which is generally evaluated away from corners and the like. Further, a feature may refer to a gap between material elements and / or a material element. In some embodiments, the average width can be about 25 nm or less, in further embodiments about 20 nm or less, and in additional embodiments about 15 nm or less. Those skilled in the art will recognize that other ranges of pitch and average width within the above explicit ranges are also contemplated and that such ranges are also within the scope of the present disclosure.

[0063] In some embodiments, the average linewidth roughness can be about 5.5 nm or less, in some embodiments about 5 nm or less, and in further embodiments about 4.5 nm or less. As shown in the examples, the linewidth roughness can be evaluated as a function of the critical dimension. The evaluation of the linewidth roughness is performed by analyzing a top-down SEM image to derive the 3σ deviation from the average linewidth. The average value includes both high-frequency and low-frequency roughness, i.e., short and long correlation lengths, respectively. The linewidth roughness of an organic resist can be characterized mainly by the long correlation length, but the organometallic coating material of the present application exhibits a significantly short correlation length. In the pattern transfer process, the short correlation roughness can be smoothed during the etching process to form a more faithful pattern. Those skilled in the art will recognize that other ranges of linewidth roughness within the above explicit ranges are also contemplated and that such ranges are also within the scope of the present disclosure. As described in U.S. Patent Application Publication No. 2020 / 0124970 to Kocsis et al., entitled "Patterned Organometallic Photoresists and Methods of Patterning," which is incorporated herein by reference, a rinse can be performed to further remove some patterning defects and improve the pattern fidelity.

[0064] After forming a desired pattern using the method of the present specification, the resulting structure can be further processed as desired to realize a functional integrated circuit.

[0065] Specific embodiments of multi-patterning Generally, organometallic patterning resists provide a useful platform for effective multipatterning with reduced process steps and good capabilities for leveraging EUV processing. In this section, three multipatterning scenarios are described in more detail using appropriate drawings, and representative embodiments of these multipatterning are described more specifically. First, continuous negative patterning is performed, and a litho-freeze-litho-freeze process is described that generally involves a freezing step based on heat treatment performed between two patterning steps. The freezing step may be optional, but generally the freezing step is desirable. Second, a litho (negative)-litho (positive / cut)-partial stripping-freezing process is described that cuts a portion of the first pattern simultaneously with positive development. Freezing can be performed optionally after the first litho step. The partial stripping step removes the remaining resist from the positive patterning after the cut step, leaving the uncut remaining portion of the first pattern formed by the negative process. In the third group of process steps, a pattern-pattern-litho process is performed, where a radiation-sensitive coating is exposed to two different mask patterns to form a composite latent image, followed by a development step. Thereafter, a composite pattern is formed by development. These processes can also be appropriately combined, as will be further described after the description of the drawings.

[0066] Figures 4 to 15 relate to a litho-freeze-litho-freeze process in which features by a second lithography process are disposed within the pattern of a first lithography process. After exposure using radiation, the first photosensitive organometallic material is patterned including the irradiated regions and non-irradiated regions. Referring to FIGS. 4 and 5, a patterned structure 100 is shown comprising a substrate 102, a hard mask layer 103, and a patterned organometallic material 104. The patterned organometallic material 104 includes condensed regions 110, 112, 116 of the irradiated coating material and non-condensed regions 118, 120 of the non-irradiated coating material. The pattern formed by the condensed regions 110, 112, 116 and non-condensed regions 118, 120 represents a latent image in the organometallic material, and the development of the latent image will be described in the following section. Materials suitable for each of these layers have been described in detail above, and the above considerations can be regarded as reproduced here as they are.

[0067] Referring to FIGS. 6 and 7, the latent image of the structure shown in FIGS. 4 and 5 is developed through contact with a developer to form a patterned structure 130. The developer composition for negative development has been described in detail above, and the considerations thereof can be regarded as part of the present considerations. After development of the image, the hard mask layer 103 is exposed along the upper surface through openings 132, 134. The openings 132, 134 are respectively located at the positions of the non-condensed regions 118, 120.

[0068] After the post-development hard bake heating of the patterned structure 130, the pattern of the organometallic material is chemically "frozen" and thus is more insoluble and stable in subsequent negative lithography processes. Referring to FIGS. 8 and 9, a patterned structure 160 is shown comprising a substrate 102, a hard mask layer 103, "frozen" organometallic materials 162, 164, 166, and a second photosensitive organometallic material 170 deposited using the solution deposition and / or vapor phase growth approaches described above. The pattern formed by the "frozen" regions 162, 164, 166 is retained under the second photosensitive organometallic material 170 regardless of the deposition approach because the frozen regions are not soluble in the solvent used for the deposition of the photosensitive organometallic material. Generally, a post-development bake to freeze the pattern is not necessary, but the structure is further stabilized with an efficient process to improve the pattern structure.

[0069] After exposure using radiation, the second photosensitive organometallic material is patterned including the irradiated and non-irradiated regions. Referring to FIGS. 10 and 11, a patterned structure 190 is shown comprising a substrate 102, a hard mask layer 103, the pre-"frozen" pattern of the organometallic materials 162, 164, 166, and a patterned organometallic material 180. The patterned organometallic material 180 comprises regions 198, 200 of the irradiated coating material and non-condensed regions 192, 194, 196 of the non-irradiated coating material. The pattern formed by the condensed regions 198, 200 is parallel to and offset from the pattern formed by the "frozen" organometallic materials 162, 164, 166. The pattern formed by the condensed regions 198, 200 and the non-irradiated regions 192, 194, 196 represents a latent image in the second organometallic material. This pattern is referred to as the second latent image.

[0070] Referring to FIGS. 12 and 13, the second latent image of the structure shown in FIGS. 10 and 11 is developed through contact with a developer for a negative-type image, forming a double-patterned line structure 220. After development of the second latent image, the organometallic materials 232, 234 are located at the positions of the condensation regions 198, 200, respectively. The "frozen" organometallic materials 162, 164, 166 are located at the positions of the condensation regions 110, 112, 116, respectively. The hard mask layer 103 is exposed along the upper surface through the openings 222, 224, 226, 228.

[0071] Referring to FIGS. 14 and 15, the etched hard mask 274 exposes the substrate 102 along the upper surface through the openings 264, 266, 268, 270. The patterned substrate 250 consists of hard mask regions 252, 254, 256, 258, 262. The hard mask regions 252, 254, 256, 258, 262 correspond to the positions of the organometallic materials 232, 234 and the "frozen" organometallic materials 162, 164, 166 shown in FIGS. 9 and 10, respectively. Further processing of the patterned substrate 250 may include, for example, etching the substrate 102 through the openings 264, 266, 268, 270 as depicted in FIG. 3. Alternatively, or additionally, deposits can be supplied to the substrate through the openings 264, 266, 268, 270, which can be performed regardless of whether the substrate is etched first or not.

[0072] Figures 16 to 21 relate to a litho-freeze-litho-freeze process in which features by a second lithography process are vertically placed on the pattern of the first lithography process. FIG. 16 shows the exposure of a radiation-patterned structure 160 (FIGS. 8 and 9) for patterning a second photosensitive organometallic material having an irradiated region and a non-irradiated region. A patterned structure 280 is shown that includes a substrate 102, a hard mask layer 103, "frozen" organometallic materials 162, 164, 166, and a patterned organometallic material 282. The patterned organometallic material 282 includes condensed regions 290, 292, 294 of the irradiated coating material and regions 284, 286, 288 of the non-irradiated coating material. The pattern formed by the condensed regions 290, 292, 294 is perpendicular to the pattern formed by the "frozen" organometallic materials 162, 164, 166. The pattern formed by the condensed regions 290, 292, 294 and the non-irradiated regions 284, 286, 288 represents a latent image in the second organometallic material. This pattern is referred to as the second latent image. Referring to FIGS. 18 and 19A to 19C, the second latent image of the structure shown in FIGS. 16 and 17 is developed through contact with a developer for a negative image to form a structure 310 patterned in a cross-hatch pattern. After development of the second latent image, organometallic materials 312, 314, and 316 are located at the positions of the condensed regions 290, 292, 294, respectively. A part of the organometallic materials 312, 314, and 316 overlaps adjacent to the "frozen" organometallic materials 162, 164, 166, but they are not cut. The "frozen" organometallic materials 162, 164, 166 are located at the positions of the condensed regions 110, 112, 116, respectively. The hard mask layer 103 is exposed along the upper surface through openings 324, 326, 328, 330, 332, 334.

[0073] After hard-baking the cross-hatch patterned structure 310, the pattern of the organometallic material is chemically "frozen" and thus more insoluble and stable to subsequent processing. Referring to FIGS. 20 and 21, the patterned substrate 340 consists of a patterned hard mask 342 having a pattern corresponding to the positions of the organometallic materials 312, 314, and 316 and the "frozen" organometallic materials 162, 164, 166 shown in FIGS. 18 and 19A-19C. The patterned hard mask 342 exposes the substrate 102 along the upper surface through the openings 344, 346, 348, 350, 352, 354. Further processing of the patterned substrate 340 may include etching the substrate 102 through the openings 344, 346, 348, 350, 352, 354, as depicted, for example, in FIG. 3. Alternatively, or additionally, deposits can be supplied to the substrate through the openings 344, 346, 348, 350, 352, 354, which can be performed whether or not the substrate is first etched.

[0074] Figures 22A - 22F relate to a litho - litho process in which features from a second lithography process cut features from a first lithography process by using positive patterning after a negative patterning step. Figures 22A and 22B show a patterned structure including an organometallic material 360 patterned in a hard mask layer 362. Generally, the hard mask layer 362 is on a substrate 102. The organometallic material 360 is a first photosensitive organometallic material that has been irradiated and at least partially condensed, but may not have been subjected to a hard - bake freeze. The hard - bake freeze process can stabilize the structure of Figure 22A, but hard - bake freeze can delay subsequent development for cutting the structure. The organometallic material 360 is developed through contact with a negative developer to form a pattern. In Figures 22C and 22D, a second photosensitive organometallic material 364 is deposited on the patterned structure of Figures 22A and 22B using the solution deposition and / or vapor - phase growth approaches described above, and is patterned using radiation to form a latent image by an irradiated region 366. In some embodiments, the first photosensitive organometallic material and the second photosensitive organometallic material may be the same material. Referring to Figure 22E, the irradiated region 366 is developed using a positive developer to form an open region 370. The positive developer further removes the organometallic material 360 exposed in the same development step. By removing both the irradiated second photosensitive organometallic material and the exposed organometallic material 360, the open region 370 exposes the hard mask layer 362. Referring to Figure 22F, the unexposed second organometallic material 364 is stripped, revealing a patterned resist 376 on the hard mask layer 362. A cut 374 through the patterned resist 376 corresponds to the open region 370. Further processing of the patterned structure of Figure 22D generally includes etching through the hard mask layer 362 to expose a portion of the substrate under the hard mask layer 362. Thereafter, the remaining patterned organometallic material can be stripped.

[0075] Figures 23A to 23D relate to a litho-litho-etch process in which latent features by a second irradiation step are added to latent features by a first lithography step and then developed in a single step to form a pattern of an organometallic material. Figure 23A shows a patterned structure including a condensed region 380 of the irradiated organometallic material and a region 382 of the non-irradiated organometallic material. The pattern formed by the condensed region 380 and the non-irradiated region 382 represents a latent image on the organometallic material. This pattern is called the first latent image. Figure 23B shows the patterned structure of Figure 23A after irradiation to form a condensed region 384 of the irradiated organometallic material. The pattern formed by the condensed region 380, the condensed region 384, and the non-irradiated region 385 represents a latent image on the organometallic material. This pattern is called a composite latent image. Referring to Figure 23C, the composite latent image of the structure shown in Figure 23B is developed through contact with a developer for a negative image, removing the non-irradiated organometallic material from the non-irradiated region 385 to form the patterned structure of Figure 23C. The patterned structure of Figure 23C includes a patterned organometallic material 388 on a hard mask layer 386. Referring to Figure 23D, after etching the hard mask layer 386 according to the patterned structure of Figure 23C, the etched hard mask 394 exposes the substrate 390 along the upper surface. The etched hard mask 394 corresponds to the position of the patterned organometallic material 388. Generally, the patterned organometallic material 388 is removed before further processing. Further processing of the patterned structure of Figure 23D may include, for example, etching the substrate 390 as depicted in Figure 3. Alternatively, or additionally, deposits can be supplied to the substrate 390 through the openings formed by the etched hard mask 394, which can be performed regardless of whether the substrate is etched first or not.

[0076] Figures 24A to 24D relate to a litho-litho-etch process that is the same as the previous process, but uses a positive developer instead of a negative developer. Figure 24A shows a patterned structure having a condensed region 394 of the irradiated organometallic material and a region 396 of the non-irradiated organometallic material. The pattern formed by the irradiated region 394 and the non-irradiated region 396 represents a latent image on the organometallic material. This pattern is called the first latent image. Figure 24B shows the patterned structure of Figure 24A after irradiation to form an irradiated region 398 of the irradiated organometallic material. The pattern formed by the irradiated region 394, the irradiated region 398, and the non-irradiated region 397 represents a latent image on the organometallic material. This pattern is called a composite latent image. Referring to Figure 24C, the composite latent image of the structure shown in Figure 24B is developed through contact with a developer for a positive image, removing the irradiated organometallic material from the irradiated region 394 and the irradiated region 398, and forming the patterned structure of Figure 24C. The patterned structure of Figure 24C includes a patterned organometallic material 400 on a hard mask layer 402. Referring to Figure 24D, after etching the hard mask layer 402 according to the patterned structure of Figure 24C, the etched hard mask 404 exposes the substrate 406 along the upper surface. The etched hard mask 404 corresponds to the position of the patterned organometallic material 400. Generally, the patterned organometallic material 388 is peeled off before further processing. Further processing of the patterned structure of Figure 24D may include, for example, etching the substrate 406 as depicted in Figure 3. Alternatively, or additionally, deposits can be supplied to the substrate 406 through the openings formed by the etched hard mask 404, which can be performed regardless of whether the substrate is etched first or not.

[0077] The various multi-patterning processes depicted in Figures 1 to 24D can generally be combined in various suitable ways as described above. The following examples illustrate a method of performing LFLF on an organic tin resist using EUV lithography.

[0078] By the multi-patterning process described in this specification, rectangular holes with an average size of about 50 nm or less, in further embodiments 40 nm or less, in other embodiments 30 nm or less, and in additional embodiments 20 nm to 30 nm can be formed. The size, in the case of a rectangular hole, refers to the diameter or diagonal length, and those skilled in the art can evaluate the appropriate size based on this for other shapes. Those skilled in the art will recognize that other ranges of hole sizes within the explicit range are also conceivable and that such ranges are also within the scope of this disclosure.

Example

[0079] Example: Double-patterning contact hole In this example, a method of double patterning using an organotin photoresist is shown, in which a first layer of a photosensitive organotin material is patterned on a substrate, and then a subsequent layer of the photosensitive organotin material is deposited on the first patterned layer and patterned perpendicular to the first pattern to result in a cross-hatch pattern.

[0080] The substrate of this example consists of a Si wafer coated with 10 nm of spin-on glass (SOG) as the lower layer, but the identity of the lower layer is not particularly important for implementing this method. Other lower layers may be used as long as they provide appropriate adhesion and sufficient lithography performance. The organotin resist used in this example was YATU1011, manufactured by Inpria Corporation and having the composition described in U.S. Patent No. 10,228,618, titled "Organotin Oxide Hydroxide Patterning Composition, Precursors, And Patterning" by Meyers et al.

[0081] The first organotin layer was deposited by spin coating at 1394 rpm, forming a film with a thickness of approximately 22 nm, and then a post-application bake (PAB) process was performed at 100 °C for 60 seconds. After the PAB process, the wafer was exposed to EUV radiation using an ASML NXE3300 scanner to form the first radiation patterning layer. After exposure, a post-exposure bake (PEB) was performed at 170 °C for 60 seconds. Next, the first patterning layer was developed and subjected to a hard bake at 250 °C for 60 seconds, where a first pattern consisting of 16.0 nm lines parallel with a 32.0 nm pitch was fabricated on the patterned substrate. This hard bake is utilized to "freeze" the pattern, in other words, to render it completely insoluble in subsequent lithography processes.

[0082] After manufacturing the first patterned substrate, a second layer of the organotin material can be deposited on the patterned substrate and subjected to PAB using the same processes and conditions employed for the formation of the first organotin layer. Next, the wafer was rotated 90°, and exposed to EUV radiation using an ASML NXE3300 scanner. Since the wafer is rotated 90° with respect to the first pattern, a second irradiation pattern perpendicular to the first one is generated during the second exposure. After exposure, the wafer was subjected to PEB at 170 °C for 60 seconds, developed, and hard baked at 250 °C for 60 seconds to form a double-patterned substrate. Figure 25 shows a CD-SEM image of the final product. A cross-hatch pattern is observed where lines in the x-direction are formed in the first patterning step and lines in the y-direction are formed in the second patterning step. This cross-hatch pattern has lines of the 16.0 nm organotin material with a line width roughness of 1.8 nm at a 32.0 nm pitch, forming square holes of approximately 16.6 nm. This structure is useful as a method for manufacturing contact holes.

[0083] In both lithography processes, the developer composition contained PGME and acetic acid as described in U.S. Patent Application No. 16 / 845,511, titled "Organometallic Photoresist Developer Compositions" by Jiang et al. Other developers, such as 2-heptanone, and others as described in U.S. Patent No. 9,310,684, titled "Organometallic Solution Based High Resolution Patterning Compositions", and U.S. Patent No. 10,228,618, titled "Organotin Oxide Hydroxide Patterning Composition, Precursors, And Patterning" by Meyers et al. may be used.

[0084] The above embodiments are intended to be illustrative and not limiting. Additional embodiments are within the scope of the claims. Further, although the present invention has been described with respect to specific embodiments, those skilled in the art will recognize that changes in form and detail may be made without departing from the spirit and scope of the invention. Any incorporation by reference of the above documents is limited so that no subject matter that is contrary to the explicit disclosure herein is ever incorporated. Unless otherwise specified, as proposed in the discussion, to the extent that a particular structure, composition, and / or process is described herein in connection with components, elements, ingredients, or other categories, the disclosure herein can include embodiments that include a particular embodiment, a particular component, element, ingredient, other category, or a combination thereof, and embodiments that are essentially composed of such a particular component, ingredient, or other category, or a combination thereof, including additional features that do not change the basic nature of the subject matter. The use of the term "about" herein refers to measurement error of a particular parameter as understood by one of ordinary skill in the art based on the teachings herein, unless otherwise explicitly stated.

Claims

1. A method of patterning a substrate, comprising: depositing a precursor composition to form a layer of a photosensitive composition on a patterned underlying structure, wherein the photosensitive composition comprises an organometallic composition having a radiation-sensitive ligand bonded to a metal, the patterned underlying structure sequentially comprises a substrate, an unpatterned hard mask layer on the substrate, and a patterned metal oxide-based material having a first pattern on the hard mask layer, the photosensitive composition is located on the hard mask layer together with the patterned metal oxide-based material, and a freezing step is not performed after the first pattern is formed; irradiating the layer of the photosensitive composition to form a latent image, wherein a pattern corresponding to the latent image is different from the first pattern, and the unpatterned hard mask layer has differential etching with respect to the irradiated photosensitive composition and the patterned metal oxide-based material; developing the latent image to form a second pattern from the irradiated photosensitive composition to form a developed structure

2. The patterned metal oxide-based material is formed by irradiating a first layer comprising a first photosensitive organometallic material on a surface of the unpatterned hard mask according to a first selected pattern, wherein the first photosensitive organometallic material comprises a radiation-sensitive ligand bonded to a metal; contacting the irradiated first layer with a developing composition to remove an unirradiated portion of the irradiated first layer to form the patterned metal oxide-based material, The method according to claim 1.

3. The method according to claim 1 or 2, further providing further development of the first pattern during the developing step.

4. The method according to claim 2, wherein the first layer has a thickness of about 1 nm to about 100 nm.

5. The method according to any one of claims 1 to 4, wherein the patterned metal oxide-based material is insoluble in an organic solvent. RSnX ３

6. The precursor composition has the formula: wherein R is a hydrocarbyl group having 1 to 31 carbon atoms, the hydrocarbyl group may have an unsaturated bond and may have a heteroatom, X is a ligand having a hydrolyzable M-X bond, X contains an alkynide, an alkoxide, a carboxylate, or a dialkylamide. The method according to any one of claims 1 to 5, comprising one or more compounds represented by

7. The method according to any one of claims 1 to 6, wherein the depositing includes vapor phase growth, spin coating, spray coating, or dip coating.

8. The method according to any one of claims 1 to 7, wherein the layer of the photosensitive composition has a thickness of about 1 nm to about 50 nm.

9. The irradiation is UV radiation or EUV radiation at a dose of about 1 mJ / cm ２ to about 200 mJ / cm ２ or an electron beam at a dose of about 30 kV and about 2 mC / cm ２ or less, according to any one of claims 1 to 8.

10. The method according to any one of claims 1 to 9, wherein the developing includes contacting a latent image with an organic solvent to form a negative image.

11. The method according to any one of claims 1 to 9, wherein the developing includes performing positive patterning as a cutting step on the patterned metal oxide-based material.

12. The method according to any one of claims 1 to 11, wherein the first pattern includes a line-space pattern, a pillar pattern, or a combination thereof, and the projection of the pattern corresponding to the latent image overlaps with the first pattern, is located within the first pattern, or is a combination thereof.

13. heating and / or irradiating the developed structure to condense the irradiated photosensitive composition and the patterned metal oxide-based material to form a composite pattern suitable for patterning the unpatterned hard mask layer; etching the unpatterned hard mask layer based on the composite pattern or a part thereof to form a patterned hard mask; removing the irradiated photosensitive composition and the patterned metal oxide-based composition to expose the patterned hard mask The method according to any one of claims 1 to 12, further comprising

14. The method according to claim 13, wherein the heating is performed at a temperature of at least 45 °C for a time of about 30 minutes or less.

15. The method according to claim 13 or 14, further comprising etching the substrate and / or supplying a deposit on the substrate based on the exposed patterned hard mask layer.

Images