Alternating copolymer chain scission photoresist

Abstract

Photopolymer resists. As resolution increases, stochastic effects due to resist material irregularities can have a greater impact on successful patterning.SOLUTION: A polymer having a hydrocarbon-substituted terminal unit and repeating units containing two different monomer units each having an extreme ultraviolet (EUV) absorbing element. The polymer has the structure: wherein x=2 or 3, A is a EUV absorbing element, R', R'', and R''' are each hydrocarbon ligands, and n is an integer greater than 1. A may be Sn, Te, Bi, or Sb. In some embodiments, R is not the same hydrocarbon species as R'. In some embodiments, R'' is the same hydrocarbon species as R' and / or R.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to photolithographic materials, and more particularly to photopolymer resists. [Background technology]

[0002] Extreme ultraviolet (EUV) lithography is a microfabrication technique that uses EUV light (e.g., λ = approximately 13.5 nm) to transfer integrated circuit patterns onto a photosensitive polymer material called photoresist or resist. The patterned resist is then used in an etching process to transfer the pattern onto a semiconductor wafer. Because EUV lithography uses light with shorter wavelengths than traditional photolithography, high-resolution patterning can be achieved. Even higher resolution can be achieved by increasing the numerical aperture (NA) of the EUV light source. As resolution increases, stochastic effects from imperfections in the resist material can have a greater impact on patterning success. Summary of the Invention

[0003] Various embodiments relate to polymers having hydrocarbon-substituted terminal units and repeat units containing two different monomer units, each having an extreme ultraviolet (EUV) absorbing element. The polymers have the structure: [ka] where x=2 or 3, A is an EUV absorbing element, R′, R″, and R′″ are each hydrocarbon ligands, and n is an integer greater than 1. A may be Sn, Te, Bi, or Sb. In some embodiments, R is not the same hydrocarbon species as R'. In some embodiments, R" is the same hydrocarbon species as R' and / or R. Additionally, R and / or R" may be the same hydrocarbon species as R'". In some embodiments, the polymer has a number average molecular weight of at least 10,000 Da to 100,000 Da.

[0004] An additional embodiment relates to a polymer having organic terminal units and repeat units containing a monomer unit and an organic monomer unit, respectively, having an EUV absorbing element. The polymer has the structure: [ka] where x=2 or 3, A is an EUV absorbing element, R is a hydrocarbon ligand, E is an organic monomer unit, E′ is a non-functional terminal unit, and n is an integer greater than 1. A can be Sn, Te, Bi, or Sb. In some embodiments, E and E' each comprise an ether linking group. In other embodiments, E and E' each comprise an ester linking group. The polymer can have a number average molecular weight of at least 10,000 Da to 100,000 Da.

[0005] A further embodiment relates to a method of forming a polymer resist. The method includes providing an alternating copolymer having repeating units with at least one EUV-absorbing monomer unit and replacing end groups of the alternating copolymer with non-reactive end units. Replacing the end groups can include reacting the alternating copolymer with a monofunctional monomer. In some embodiments, providing the alternating copolymer includes polymerizing two different types of difunctional EUV-absorbing monomers. In other embodiments, providing the alternating copolymer includes polymerizing a difunctional EUV-absorbing monomer with a difunctional organic monomer, such as a diol or a dicarboxylic acid. The method can also include applying the polymer resist to a substrate and lithographically patterning the polymer resist. [Brief explanation of the drawings]

[0006] [Figure 1A] 1A-1C are block diagrams illustrating alternating and random copolymers, according to some embodiments of the present invention. [Figure 1B]FIG. 2 is a block diagram illustrating polymer resist conformation according to some embodiments of the present invention. [Figure 2] FIG. 1 is a flow diagram illustrating a method of forming a polymer resist according to some embodiments of the present invention. [Figure 3A] 1 is a chemical reaction diagram illustrating a method of forming an alternating copolymer resist from EUV absorbing monomers according to some embodiments of the present invention. [Figure 3B] 1 is a chemical reaction diagram illustrating a method of forming an alternating copolymer resist from EUV absorbing monomers according to some embodiments of the present invention. [Figure 4A] 1 is a chemical reaction diagram illustrating a method of forming an alternating copolymer resist from EUV absorbing monomers and organic monomers according to some embodiments of the present invention. [Figure 4B] 1 is a chemical reaction diagram illustrating a method of forming an alternating copolymer resist from EUV absorbing monomers and organic monomers according to some embodiments of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0007] Photolithography is a technique commonly used in semiconductor manufacturing to etch integrated circuit patterns onto semiconductor wafers. Photolithographic patterning involves coating a substrate with a light-sensitive resist material, referred to herein as photoresist or resist. The resist is selectively masked by a photomask designed with the integrated circuit pattern. When the unmasked areas of the resist are exposed to a light source (e.g., visible light, ultraviolet (UV) light, or extreme ultraviolet (EUV) light, or a combination thereof), a chemical reaction occurs that renders selected portions of the photoresist soluble in a developer solution and therefore removable during the development stage of the lithography process.

[0008] Photoresists can be classified as positive or negative. Upon exposure to a light source, the unmasked areas of negative resist become insoluble, for example, by light-induced polymerization or crosslinking. In contrast, the unmasked portions of positive resist photosolubilize upon exposure to a light source. For example, positive photopolymer resists can undergo chain scission upon photon absorption. Removal of the soluble portions during the development step creates patterned resist, which is used to transfer the pattern into a semiconductor or other substrate material during a subsequent etching step.

[0009] Traditional photolithography has used visible light, UV light, or both (e.g., approximately 193 nm to 436 nm) as a photon source, but these wavelengths are too long for the high-resolution patterning required for many of today's technologies. Extreme UV lithography uses light in the 10-124 nm (EUV) range. For high-resolution patterning in semiconductor manufacturing, EUV wavelengths of approximately 10-13.5 nm, generated by laser-driven tin (Sn) plasma sources, are often used. Furthermore, next-generation techniques such as multi-patterning and high-numerical-aperture (NA) EUV lithography are being developed to achieve even higher resolution. EUV lithography typically uses a light source with an NA of 0.33 to achieve approximately 13 nm resolution, while high-NA EUV lithography can use a 0.55 NA light source. While this may enable smaller pattern dimensions, it presents various challenges.

[0010] For example, the impact of stochastic effects due to material variability increases. Because of the lack of a pellicle at these dimensions and the fragility and susceptibility to pattern destruction, this type of resist may require reduced exposure area, for example, using dark-field reticles and positive-tone resists. However, most next-generation resists developed for high-NA EUV lithography are negative-tone resists, while positive-tone resists generally require additional chemical amplifiers (e.g., photoacid generators (PAGs), photon-decomposable bases (PDBs), etc.). Therefore, there is a need for positive-tone photoresists with improved compositional uniformity that do not require minor components such as chemical amplifiers.

[0011] Disclosed herein is a technique for producing positive resists with reduced compositional variability. These resists use alternating copolymers containing monomer units containing elements that absorb EUV radiation ("EUV-absorbing elements"). For example, the alternating copolymer can be poly(stannane). Absorption of EUV radiation causes chain scission, solubilizing the unmasked regions of the resist without the need for minor components such as chemical amplifiers, catalysts, etc. The use of copolymers allows for excellent control of resist properties by varying the structure and reactivity of the monomer units. The polymerization method used to form the resist avoids random distribution of units, which can lead to material variability. Furthermore, by replacing functional end groups of the alternating copolymer with non-reactive end units, the polymer resist chains can be terminated at controlled lengths.

[0012] 1A is a block diagram 100 illustrating an alternating copolymer 110 and a random copolymer 120, according to some embodiments of the present invention. As used herein, an "alternating copolymer" refers to a strictly alternating copolymer, which may also be referred to as a homopolymer, having repeat units containing two or more species of monomer ("monomer units"). Copolymers that include adjacent repeat units of the same monomer species in addition to alternating repeat units are referred to herein as "random copolymers."

[0013] The alternating copolymer 110 includes n repeat units, each containing two different monomer units (represented by gray and black squares, respectively). The random copolymer 120 includes n repeat units of a first monomer (gray squares) and m repeat units of a second monomer (black squares). As used herein, the subscripts n and m may each refer to any integer greater than 1, unless otherwise specified. The length of the polymer chain may vary based on the desired application and resist properties. In some embodiments, the number average molecular weight of the alternating copolymer 110 is about 100,000 Da (g / mol) or greater. However, the average molecular weight of the alternating copolymer 110 and / or the random copolymer 120 may, in some embodiments, be in the range of at least 10,000 Da to 100,000 Da, 400 Da to 10,000,000 Da, etc.

[0014] At least one of the monomer units of the alternating copolymer 110 includes an element that absorbs EUV radiation. These may be elements that highly absorb EUV radiation. For example, one or both of the monomer units may contain atoms of tin (Sn), antimony (Sb), tellurium (Te), or bismuth (Bi). Elements that highly absorb EUV radiation include those with a high absorbing capacity of 1000 volts. 7 cm 2 / mol or greater. The EUV-absorbing monomer units may be derived from the polymerization of difunctional EUV-absorbing monomers, such as diaryl- or dialkylstannanes. In some embodiments, one of the monomers is an organic monomer unit derived from a condensation polymerization reaction between a difunctional EUV-absorbing monomer and a difunctional organic monomer, such as a diol or dicarboxylic acid monomer.

[0015] Random copolymer 120 has functional groups corresponding to its monomer repeat units (gray and black boxes) at each end of the chain ("functional end groups" or "living ends"). In contrast, alternating copolymer 110 includes terminal units (gray and black checkboxes) with non-reactive alkyl and / or aryl moieties intended to prevent further polymerization or crosslinking. As used herein, "non-reactive" refers to species that do not have functional groups (e.g., functional end groups) available for further reactions such as cyclization, branching, crosslinking, etc.

[0016] FIG. 1B is a block diagram illustrating polymer resist conformation, according to some embodiments of the present invention. Polymer resist 130 is an alternating copolymer, and polymer resist 140 is a random copolymer. In both polymer resists 130 and 140, gray and black squares represent different monomer units. The striped boxes and checkboxes on each chain of polymer resist 130 represent non-reactive end units. In some embodiments, polymer resist 130 may be an example of alternating copolymer 110 (FIG. 1A) deposited on a substrate (not shown). Similarly, polymer resist 140 may be an example of random copolymer 120 (FIG. 1A) deposited on a substrate (not shown).

[0017] The two monomer species of polymer resist 140 can be the same as those of polymer resist 130, but polymer resists 130 and 140 can also have different monomer species. The number, length, shape, relative size, etc. of the polymer chains in FIG. 1B are for illustrative purposes only and should not be interpreted as actual resist compositions. For example, a resist can have any number of polymer chains with any suitable number of monomers. This can depend on factors such as the molecular weight of the polymer, the reactivity of the polymer, the area and thickness of the resist, etc. Alternating and random copolymers with three or more monomer species are not illustrated in FIG. 1B, but they can have substantially similar conformational differences to those of polymer resists 130 and 140.

[0018] The polymer resist 130 has a more ordered conformation than the polymer resist 140. The chain length of the polymer resist 130 can be controlled by the addition of terminal units, as described in more detail below. Furthermore, the non-reactive terminal units can prevent future inter-chain reactions (e.g., cyclization) that could reduce the stability and structural integrity of the polymer resist 130. In contrast, the chains of the polymer resist 140 terminate with functional groups that can participate in further polymerization, cyclization, crosslinking, etc. The strictly alternating monomers and consistent chain lengths of the polymer resist 130 can provide a more ordered resist structure than the random distribution of monomers in the polymer resist 140. For example, the polymer resist 130 avoids the blockiness present in the polymer resist 140. Blockiness refers to the proximity of comonomers greater than a statistical distribution. This can cause conformational variations in the polymer, leading to non-uniform spatial distribution of elements that highly absorb EUV radiation, resulting in local spatial variations in EUV resist sensitivity and therefore increasing the risk of stochastic defects. A more ordered structure of the polymer resist 130 can increase the efficiency of EUV absorption and reduce stochastic errors.

[0019] 2 is a flow diagram illustrating a method 200 of forming a polymer resist according to some embodiments of the present invention. Monomer species and terminal units are selected, as described in operation 210. At least one of the monomer species contains an EUV-absorbing element, such as Sn, Te, Bi, or Sb. Bifunctional EUV-absorbing monomers can be represented by the general formula R2MX2 or R3ZX2, where R represents a hydrocarbon ligand, such as an alkyl (e.g., methyl, ethyl, propyl, butyl, cyclohexyl, etc.) or aryl (e.g., phenyl, tolyl, naphthyl, etc.) group; X represents an anionic group, such as a hydride, halide, or dialkylazanide; M represents an EUV-absorbing element, such as Sn or Te; and Z represents an EUV-absorbing element, such as Sb or Bi. For example, the EUV absorbing monomer selected may be a bifunctional compound such as diphenyltin dihydride, bis(diethylamino)dimethyltin, diethyltin dichloride, dibutyltellurium diiodide, triphenylantimony(V) dichloride, diacetyloxy(triphenyl)bismuth, etc. Although not described herein, compounds containing EUV absorbing elements other than Sn, Sb, Bi, or Te may be used in some embodiments. Additionally, the hydrocarbon R groups in an R2MX2 or R3MX2 molecule may not be the same type of hydrocarbon in some embodiments.

[0020] Difunctional organic monomers such as dicarboxylic acids and diols may also be selected. Examples of dicarboxylic acids include camphoric acid, 1,4-cyclohexanedicarboxylic acid, 2,3-norbornanedicarboxylic acid, bicyclo[2.2.2]octane-1,4-dicarboxylic acid, 1,3-adamantanedicarboxylic acid, 5,7-dimethyladamantane-1,3-dicarboxylic acid, 3-carboxyadamantane-1-acetic acid, 1,3-adamantanediacetic acid, terephthalic acid, p-phenylenediacetic acid, 1,4-phenylenedipropionic acid, 1,1'-ferrocenedicarboxylic acid, 1,1'-ferrocenediacetic acid, and ferrocenyldicarboxylic acid analogs (wherein iron is replaced by Ru, V, Zr, Hf, Ti, or Sn). Examples of diols include bisphenol A, hydroquinone, 4-(4-hydroxyphenyl)tellanylphenol, 1,4-biphenyldimethanol, 1,4-cyclohexanedimethanol, 1,4-cyclohexanediol, 4,4'-bicyclohexanol, tricyclodecane dimethanol, ferrocenyl diols (e.g., 1,1'-ferrocenedimethanol, 1,1'-ferrocenediethanol, etc.), and ferrocenyl diol analogs (wherein iron is replaced with Ru, V, Zr, Hf, Ti, or Sn). However, as will be understood by those skilled in the art, various diol or dicarboxylic acid monomers not described herein may be used in some embodiments. Additionally, other difunctional organic monomers may be used in some embodiments (e.g., diamines). It should be noted that while some of the above organic monomers contain metal or metalloid atoms, they are referred to herein as organic monomers to indicate that the inorganic atoms do not participate in the polymerization (e.g., polycondensation reaction).

[0021] Selected monomers are polymerized to form an alternating copolymer, as described in operation 220. The polymerization may be a polycondensation reaction. For example, an alternating copolymer can be formed by reacting at least two different species of EUV-absorbing monomers (e.g., bis(diethylamino)dialkyltin and diaryltin dihydride). An alternating copolymer can also be formed from an EUV-absorbing monomer and an organic monomer. For example, at least one species of difunctional EUV-absorbing monomer can be reacted with at least one species of difunctional organic monomer (e.g., a diol or dicarboxylic acid monomer). Exemplary reactions for forming polyether-organotin alternating copolymers and polyester-organotin alternating copolymers are discussed in more detail with respect to FIGS. 4A and 4B. The amount of time, temperature, solvent, and other reaction conditions can depend on the monomer species and the scale of the reaction, as will be understood by those skilled in the art. Examples of polymerization reactions are discussed in more detail below.

[0022] The terminal units are attached to the ends of the alternating copolymer to form the alternating copolymer resist, as described in operation 230. The species of terminal units selected in operation 210 can be dissolved in an appropriate solvent (e.g., depending on monomer polarity, molecular mass / structure, etc.) and mixed with the alternating copolymer formed in operation 220. It should be noted that while terminal unit selection is described in operation 210, the selection can occur any time prior to or in operation 230. Furthermore, in some embodiments, the alternating copolymer with living ends can be obtained from another source (e.g., a commercial source) rather than being formed in operation 220.

[0023] The terminal units may be selected from monofunctional compounds similar to the above examples of difunctional EUV-absorbing monomers and / or organic monomers. The monofunctional EUV-absorbing terminal units may be represented by the general formula R3MX or R4ZX, where, as in the general difunctional EUV-absorbing monomer formula, R represents a hydrocarbon ligand, X represents an anionic group, M represents an EUV-absorbing element such as Sn or Te, and Z represents an EUV-absorbing element such as Sb or Bi.

[0024] Examples of monofunctional EUV absorbing monomers used in the terminal units include trimethyltin hydride, triethyltin hydride, tripropyltin hydride, tributyltin hydride (e.g., (n-Bu)3SnH or (t-Bu)3SnH), triphenyltin hydride, trimethyltin diethylamide, triethyltin diethylamide, tripropyltin diethylamide, tri-n- or tri-t-butyltin diethylamide, trimethyltellurium iodide, tetraphenylantimony bromide, tetra-m-tolylbismuth iodide, and tetramethylbismuth chloride.

[0025] The EUV absorbing monomer and terminal unit are reacted (e.g., in operations 220 and 230) to form a compound having the following general structure: [ka] where A is an EUV absorbing element, x=2 or 3 depending on the valence of A, and R, R', R'', and R''' are each hydrocarbon ligands. The hydrocarbon ligands R and R' of the repeating units are not the same type of hydrocarbon, but the terminal hydrocarbon ligands R" and R'" can independently be the same type as R, R', or different hydrocarbons. Polymer structure and synthesis are discussed in more detail below.

[0026] Examples of organic monomers used as terminal units can include monofunctional carboxylic acid monomers such as cyclohexanecarboxylic acid, 2-norbornanecarboxylic acid, bicyclo[2.2.2]octane-1-carboxylic acid, 1-adamantanecarboxylic acid, 3,5-dimethyladamantane-1-carboxylic acid, 1-adamantaneacetic acid, benzoic acid, phenylacetic acid, 3-phenylpropionic acid, etc. Additional examples can include ferrocenecarboxylic acid, ferroceneacetic acid, ferrocenepropionic acid, and analogs thereof (wherein iron is replaced with Ru, V, Zr, Hf, Ti, or Sn). Examples of organic terminal units may also include 4-phenyltellanylphenol, tricyclodecanemethanol, phenylmethanol, phenylethanol, phenylpropanol, 4-biphenylmethanol, ferrocenyl alcohol (e.g., ferrocenemethanol) and analogs thereof (wherein iron is replaced by Ru, V, Zr, Hf, Ti, or Sn), 4-cyclohexylcyclohexanol, 4-phenylphenol, and the like.

[0027] When organic monomers are included in operations 220 and 230, the alternating copolymer resist may have the following general structure: [ka] where A is an EUV absorbing element, x=2 or 3 depending on the valence of A, E is an organic monomer unit, E′ is an organic terminal unit, and R is a hydrocarbon ligand. For example, E' can be a monohydroxy or monocarboxylic acid compound attached to the polymer terminus via a condensation reaction. Examples of polymer structures and syntheses are discussed in further detail with respect to Figures 3A-4B.

[0028] The alternating copolymer resist formed in operation 230 can be applied to a substrate, as described in operation 240. The substrate can be any substrate suitable for lithographic patterning of photoresist (e.g., a semiconductor wafer, an inorganic hard mask, a polymer-brushed inorganic substrate, etc.). Various coating methods can be used to apply the resist. Examples of these coating methods include spin coating, spray coating, dip coating, knife-edge coating, printing techniques (e.g., inkjet or screen printing), spin casting, etc. Application can be performed in a single coating step or multiple coating steps. Multiple coating steps can provide greater control over the coating process. For example, a series of spin coatings can be used to provide a desired thickness, which can range from a few nanometers to several microns. After the photoresist is coated on the substrate, additional heating and / or solvent evaporation steps can be performed to harden the photoresist layer. In some embodiments, the resist thickness ranges from approximately 30 nm to 50 nm, but can also range from approximately 1 nm to 500 μm.

[0029] However, in some embodiments, method 200 omits operation 240. In other embodiments, additional steps can be performed after forming the photoresist in operation 240. These steps are not illustrated in FIG. 2 but can include lithographic patterning with EUV light. Various EUV light sources can be used. EUV light sources for lithography typically have a central wavelength of 13.5 nm and high average power (e.g., 100 W or greater) with a 2% bandwidth. For example, laser-driven tin (Sn) plasma can be used, using a high-power drive laser with a wavelength of approximately less than 1 μm. In some embodiments, the drive laser is a pulsed laser. However, the drive laser can also be a solid-state laser, a gas discharge laser, or an excimer laser. It should also be noted that in some embodiments, patterning can be performed with electron-beam (e-beam) lithography or immersion photolithography rather than EUV lithography. A photomask having a desired pattern is used to partially shield the alternating copolymer resist before exposure to the energy source. When the photoresist is exposed to EUV light, a photoinduced polymer chain scission reaction occurs in the unmasked portions of the photoresist.

[0030] Photolithography methods involving alternating copolymers having terminal units disclosed herein can be used to fabricate integrated circuit chips for use in electronic devices. These integrated circuit chips can be distributed by manufacturers as raw wafers, as bare die, packaged in single-chip form (e.g., a plastic carrier with leads attached to a motherboard or other carrier), packaged in multi-chip form (e.g., a ceramic carrier with surface and / or embedded wiring), etc. Chips can be integrated with other chips, circuit elements, signal processing equipment, etc. Examples of end products that can contain chips include computing devices (e.g., computer products including a display, keyboard or other input device, and processor), toys, consumer electronics, automotive parts, etc. In addition to acting as a chain-scission resist, the alternating copolymer resists disclosed herein, in some embodiments, can be used to prevent biofouling on underwater surfaces, improve ion beam etching performance, etc.

[0031] 3A and 3B are chemical reaction diagrams illustrating methods 300 and 305 of forming an alternating copolymer resist from EUV-absorbing monomers, according to some embodiments of the present invention. Method 300 begins with obtaining an alternating copolymer 310 from two difunctional organotin monomers. While alternating copolymer 310 can be obtained using any suitable synthesis method, in some embodiments, alternating copolymer 310 can be obtained from another source (e.g., a commercial source). An exemplary synthesis (not shown) of alternating copolymer 310 can include a polycondensation reaction between the difunctional organotin monomers, diphenyltin dihydride (PhSnH), and bis(diethylamino)dimethyltin (MeSn(EtN)). Approximately equimolar amounts of MeSn(EtN) and PhSnH can be combined in a mixture of solvents such as diethyl ether (EtO) and toluene. The mixture is reacted (e.g., with stirring) in the substantial absence of light and oxygen (e.g., in a reaction vessel shielded from ambient light and maintained under an argon or nitrogen atmosphere) at about 0° C. for about 3 hours. The reaction produces the illustrated alternating copolymer 310 (-[PhSn-alt-MeSn] with hydride and diethylamino functional end groups). n As will be appreciated by those skilled in the art, similar reaction conditions can be used to form alternating copolymers from other difunctional EUV absorbing monomers.

[0032] The terminal units are attached to the ends of the alternating copolymer 310 to form the alternating copolymer resist 320. Method 300 uses two species of monofunctional organotin monomers: triphenyltin hydride (PhSnH) and trimethyltin diethylamide (MeSnNEt). For example, at least two equivalents (based on the approximate number of alternating copolymer chains) of the monofunctional organotin monomer can be mixed with the alternating copolymer 310. In some embodiments, PhSnH and MeSnNEt can be combined with the alternating copolymer 310 in EtO / toluene at about 0° C. This reaction results in an alternating copolymer resist 320 having two species of terminal units, triphenyltin and trimethyltin.

[0033] In method 305 (FIG. 3B), at least two equivalents (based on the approximate number of alternating copolymer chains) of monofunctional organotin monomers having the same R group, triphenyltin diethylamide (PhSn(EtN)) and PhSnH, are mixed with alternating copolymer 310. This reaction can be carried out using conditions substantially similar to those of method 300, but results in alternating copolymer resist 330 having symmetric triphenyltin end units. Similarly, an alternating copolymer resist (not shown) having symmetric trimethyl end units can be formed by reacting alternating copolymer 310 with, for example, MeSn(EtN) and trimethyltin hydride (MeSnH). In some embodiments, at least one end unit can be replaced with another trifunctional organotin monomer (e.g., tributyltin hydride).

[0034] 4A and 4B are chemical reaction diagrams illustrating methods 400 and 405 of forming an alternating copolymer resist from EUV-absorbing monomers and organic monomers, according to some embodiments of the present invention. Method 400 (FIG. 4A) begins with obtaining a polyester organotellurium alternating copolymer 410 from a difunctional organotellurium monomer, di-n-butyltellurium diiodide (n-BuTeI), and a dicarboxylic acid monomer, 1,4-cyclohexanedicarboxylic acid. Method 405 (FIG. 4B) begins with obtaining a polyether organotin alternating copolymer 420 from a difunctional organotin monomer, BuSnCl, and a diol monomer, 1,4-cyclohexanedimethanol. While alternating copolymers 410 and 420 can be obtained using any suitable method (see below), in some embodiments, alternating copolymers 410 and / or 420 can be obtained from another source (e.g., a commercial source).

[0035] 4A, an exemplary synthesis (not shown) of alternating copolymer 410 can include dissolving 1,4-cyclohexanedicarboxylic acid and a base, such as sodium hydroxide (NaOH), in water. An approximately equimolar amount of Bu2TeI2 dissolved in an organic solvent, such as heptane, can be added to the 1,4-cyclohexanedicarboxylic acid solution. The resulting mixture can be stirred for about 1 minute or less (e.g., between about 20 seconds and 1 minute). However, the reaction can be allowed to proceed for any suitable length of time (e.g., between about 1 minute and 1 hour or longer).

[0036] 4B, an exemplary synthesis (not shown) of alternating copolymer 420 can include dissolving 1,4-cyclohexanedimethanol in water. In some embodiments, a base such as NaOH can be added to the aqueous solution. The resulting mixture can be stirred for about 1 minute or less (e.g., between about 20 seconds and 1 minute). However, the reaction can be allowed to proceed for any suitable length of time (e.g., between about 1 minute and 1 hour or longer).

[0037] In methods 400 and 405, terminal units are attached to alternating copolymers 410 and 420, respectively, by adding a monofunctional organic monomer. In method 400 (FIG. 4A), a monofunctional alcohol, cyclohexanemethanol, is mixed with alternating copolymer 410. This results in alternating copolymer resist 430 having ester-linked cyclohexane terminal units. In method 405 (FIG. 4B), a monofunctional carboxylic acid monomer, cyclohexanecarboxylic acid, is mixed with alternating copolymer 420. This results in alternating copolymer resist 440 having ether-linked methylcyclohexane terminal units. As will be appreciated by those skilled in the art, methods 400 and 405 can be modified to obtain similar alternating copolymer resists with different terminal units by substituting different types of monofunctional alcohols and carboxylic acids. Examples of monofunctional organic monomers that can be used are discussed in more detail below with respect to FIG. 2. In some embodiments (not shown), monofunctional EUV absorbing monomers (e.g., tributyltin chloride, tributyltellurium iodide, tetramethylantimony iodide, etc.) can replace the monofunctional carboxylic acid and alcohol monomers as terminal units.

[0038] In some embodiments, the compounds disclosed herein can have additional moieties such as epoxide, hydroxyl, propylene carbonate, alkyl halide, ester, alkyne, amine, isocyanate, acid chloride, chloroformate, thiol, oxirane, silyl, carboxylic acid, alkoxyl, alkyl, etc. As used herein, "alkyl" refers to a C1-C6 alkyl group that may be linear, branched, or cyclic. 100 Examples of alkyl groups include methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, sec-butyl, tert-butyl, pentyl, hexyl, octyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, and cyclooctyl.

[0039] The compounds described herein may contain one or more chiral centers. Unless otherwise noted, the disclosed structures encompass all stereoisomers, conformers, rotamers, isomers, and enantiomers of the represented compounds. Furthermore, polymers or other materials containing the disclosed compounds can include racemic forms of the compounds as well as individual stereoisomers, as well as mixtures containing any of these. Substituents on the compounds described herein may participate in additional chemical reactions, transformations, or interactions, which may include synthesis; degradation; single or double substitution reactions, or both; oxidation / reduction reactions; acid / base reactions; nucleophilic, electrophilic, or radical substitution reactions; addition / elimination reactions; crosslinking reactions; or polymerization reactions, or combinations thereof.

[0040] Where isomers of a named alkyl, alkenyl, alkoxy, aryl, or other functional group exist (e.g., n-butyl, iso-butyl, sec-butyl, and tert-butyl), a reference to a member of the group without specifying a particular isomer (e.g., butyl) is intended to include all isomers of that family (e.g., n-butyl, iso-butyl, sec-butyl, and tert-butyl). Furthermore, unless otherwise specified, a reference to one member of a group (e.g., n-butyl) can include the remaining isomers of that family (e.g., iso-butyl, sec-butyl, and tert-butyl). This may depend on the steric or other properties of the isomers, as understood by those skilled in the art.

[0041] Unless otherwise noted, chemical reactions are carried out at ambient conditions or under slight heating without special atmospheres or headspaces, and may be carried out using standard organic solvents to control mixing properties such as viscosity and flow index. Standard procedures for reaction quenching, solvent removal, and purification are performed. Room temperature is between about 15°C and 30°C unless otherwise indicated. Ranges (e.g., time, concentration, temperature, etc.) set forth herein include both endpoints and all numbers between the endpoints. Unless otherwise specified, the use of "about," "approximately," or a tilde (~) in relation to ranges applies to both ends of the range (e.g., "approximately 1g to 5g" should be interpreted as "approximately 1g to approximately 5g"), and in relation to lists of ranges, applies to each range in the list (e.g., "approximately 1g to 5g, 5g to 10g, etc." should be interpreted as "approximately 1g to about 5g, about 5g to about 10g, etc."). Unless otherwise indicated, modifiers such as "about," "approximately," and "~" refer to + / - 10% of a recited value, range of values, or endpoints of one or more ranges of values.

[0042] The methods discussed herein and their accompanying drawings should not be construed as limiting. Those skilled in the art will recognize that various techniques can be used that vary the conditions, ingredients, methods, etc., ultimately producing an alternating copolymer resist. Additionally, conditions can be optionally modified during the process. Furthermore, in some embodiments, methods can be added, omitted, or performed in an alternate order while still remaining within the scope of the present invention, as will be understood by those skilled in the art. It should also be noted that the methods can be performed by a single entity or by multiple entities. For example, a first entity can prepare the alternating copolymer, a second entity can prepare a resist therefrom, and a third entity can perform EUV lithography using the resist.

[0043] In a preferred embodiment of the present invention, the following structure: [ka] where x=2 or 3; A is an EUV absorbing element; R, R', R'', and R''' are each hydrocarbon ligands; where n is an integer greater than 1. A polymer having the formula: Preferably, A is Sn, Te, Bi, or Sb. Preferably, R is not the same type of hydrocarbon as R'. R" may be the same type of hydrocarbon as R'. R" may be the same type of hydrocarbon as R'". R" may be the same type of hydrocarbon as R'". R" may be the same type of hydrocarbon as R'". R" may be the same type of hydrocarbon as R. The polymer may have a number average molecular weight of at least 10,000 Da to 100,000 Da.

Claims

1. The following structure: 【Chemistry 1】 wherein x=2 or 3; A is an EUV absorbing element selected from the group consisting of Sn, Te, Bi, and Sb; R, R', R'', and R''' are each hydrocarbon ligands; n is an integer greater than 1) A polymer resist for EUV lithography comprising a polymer having:

2. The polymer resist of claim 1, wherein A is Sn, and in the structure, -A-(R'') x+1 and -A-(R''') x+1 are each independently a non-reactive terminal unit selected from the group consisting of triphenyltin, trimethyltin, and tributyltin.

3. A polymer resist as described in claim 1 or 2, wherein the polymer has a number average molecular weight of 10,000 Da to 100,000 Da.

4. A polymer resist described in any one of claims 1 to 3, which does not contain a chemical amplifier.

5. A method for producing a polymer resist for EUV lithography, comprising: providing an alternating copolymer having repeat units each having at least one extreme ultraviolet (EUV) absorbing monomer unit selected from the group consisting of Sn, Te, Bi, and Sb; reacting an end group of the alternating copolymer with a monofunctional EUV-absorbing end unit to attach a non-reactive end unit to the alternating polymer; including the following structure: 【Chemistry 2】 wherein x=2 or 3; A is the EUV absorbing element selected from the group consisting of Sn, Te, Bi, and Sb; R, R', R'', and R''' are each hydrocarbon ligands; n is an integer greater than 1) forming a polymer having The polymer resist does not contain a chemical amplification agent; method.

6. Coating the polymer resist according to any one of claims 1 to 4 onto a substrate; lithographically patterning the polymer resist by exposing it to EUV light; Including, a photoinduced polymer chain scission reaction occurs in the portion of the polymer resist exposed to the EUV light; Semiconductor manufacturing methods.

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