Azastannatranes, stannatranes, and methods for their preparation and use

Abstract

Two classes of cyclic tin compounds are described, trioxa-aza-1-stannabicyclo-[3.3.3]-undecanes, also known as stannatranes, and tetraaza-1-stannabicyclo-[3.3.3]-undecanes, also known as azastannatranes, as well as methods for their preparation. These cyclic tin compounds are resistant to rearrangement, and no generation of dialkyltin impurities is observed during the synthesis, purification, or deposition of these compounds to form oxostannate films.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Provisional Patent Application No. 63 / 294,089, filed December 28, 2021, the disclosure of which is incorporated by reference in its entirety herein. [Background technology]

[0002] As semiconductor fabrication continues to advance, feature sizes continue to shrink, driving the need for new processing methods. Certain organotin compounds have been shown to be useful for the deposition of tin oxide hydroxide coatings in applications such as extreme ultraviolet (EUV) lithography techniques. For example, alkyltin compounds result in radiation-sensitive Sn-C bonds that can be used to lithographically pattern structures.

[0003] Materials used in microelectronics fabrication are required to be extremely pure, with strict limits on organic contamination (e.g., by-products of reactions), metal contamination, and particulate contamination. Purity requirements are typically stringent, especially for lithography applications, where the chemicals come into contact with semiconductor substrates and contain the dialkyltin by-product diisopropyltris(dimethylamino)stannane (( i Metalorganic impurities in compounds such as Pr(Sn(NMe2)3) can affect the properties of the resulting film. The exact purity target is determined by a variety of factors, including performance metrics, but a typical minimum purity target is greater than 99.9%. Residual metals present in the chemicals can deposit on the semiconductor substrate and degrade the electrical performance of the fabricated device. Typical specifications for metals are less than 10 ppb for individual metals and not more than about 100 ppb for total metals.

[0004] The processing and performance of semiconductor materials can also be sensitive to dialkyltin contaminants. Dialkyltin impurities R2SnX2, e.g., R2SnCl2, R2Sn(NMe2)2, etc., are often responsible for outgassing after vapor deposition or spin-on coating processes, since oxostannate cluster films are less dense when the films contain dialkyl groups. Dialkyltin compounds are often minor components in monoalkyltin compounds as by-products of synthesis, redistribution during storage, or formation during deposition. Proper control of dialkyltin contaminants is required to produce microelectronic products using EUV lithography. The high purity required by the mono-alkyltin precursor manufacturing process is a challenge. Azastannatranes and stannatranes are attractive because their chemical structures resist the redistribution reactions that lead to the formation of dialkyltin derivatives, allowing the deposition of high purity tin-containing films. Summary of the Invention [Means for solving the problem]

[0005] In one embodiment, the present disclosure relates to a compound of formula (I): [ka] wherein R1 is a substituted or unsubstituted, linear or branched alkyl group having 1 to about 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to about 20 carbon atoms, or a substituted or unsubstituted alkenyl group having 2 to about 10 carbon atoms; and each R2 is independently hydrogen or a substituted or unsubstituted, linear or branched alkyl group having 1 to about 10 carbon atoms, with the proviso that at least one R2 is not hydrogen. The present invention relates to stannatranes having the formula:

[0006] In a second embodiment, the present disclosure relates to a compound represented by formula (II): [ka] (wherein R1 is a substituted or unsubstituted, linear or branched alkyl group having 1 to about 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to about 20 carbon atoms, or a substituted or unsubstituted alkenyl group having 2 to about 10 carbon atoms; each R2 is independently hydrogen or a substituted or unsubstituted, linear or branched alkyl group having 1 to about 10 carbon atoms; and each R3 is independently hydrogen or a substituted or unsubstituted, linear or branched alkyl group having 1 to about 10 carbon atoms, with the proviso that at least one R3 is not hydrogen.) The present invention relates to azastannatrane having the formula:

[0007] In summary, the following embodiments are proposed as being particularly preferred within the scope of the present invention.

[0008] Embodiment 1: Formula (I): [ka] wherein R1 is a substituted or unsubstituted, linear or branched alkyl group having 1 to about 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to about 20 carbon atoms, or a substituted or unsubstituted alkenyl group having 2 to about 10 carbon atoms; and each R2 is independently hydrogen or a substituted or unsubstituted, linear or branched alkyl group having 1 to about 10 carbon atoms, with the proviso that at least one R2 is not hydrogen. A stannatran having the formula:

[0009] Embodiment 2: Formula 1-n-butyl-3,7,10-trimethyl-2,8,9-trioxa-5-aza-1-stannabicyclo[3.3.3]undecane: [ka] The stannatran according to embodiment 1, having the formula:

[0010] Embodiment 3: Formula 1-(3,3,3-trifluoropropyl)-3,7,10-trimethyl-2,8,9-trioxa-5-aza-1-stannabicyclo[3.3.3]undecane: [ka] The stannatran according to embodiment 1, having the formula:

[0011] Embodiment 4: Formula 1-isopropyl-3,7,10-trimethyl-2,8,9-trioxa-5-aza-1-stannabicyclo[3.3.3]undecane: [ka] The stannatran according to embodiment 1, having the formula:

[0012] Embodiment 5: The stannatran of any one of embodiments 1 to 4, having a purity of at least about 99.9%.

[0013] Embodiment 6: The stannatran of any one of embodiments 1-5, containing less than about 0.1% of a dialkyltin compound.

[0014] Embodiment 7: A method for forming the stannatran according to any one of embodiments 1 to 6, comprising the steps of: A method comprising the step of reacting an alkali metal alkoxide with triisopropanolamine and an alkyltin trichloride compound having the formula R1SnCl3.

[0015] Embodiment 8: A method for forming the stannatran according to any one of embodiments 1 to 6, comprising the steps of: A method comprising the step of reacting an alkyltris(dimethylamino)tin compound having the formula R1Sn(NMe2)3 with triisopropanolamine.

[0016] Embodiment 9: Formula (II): [ka] (wherein R1 is a substituted or unsubstituted, linear or branched alkyl group having 1 to about 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to about 20 carbon atoms, or a substituted or unsubstituted alkenyl group having 2 to about 10 carbon atoms; each R2 is independently hydrogen or a substituted or unsubstituted, linear or branched alkyl group having 1 to about 10 carbon atoms; and each R3 is independently hydrogen or a substituted or unsubstituted, linear or branched alkyl group having 1 to about 10 carbon atoms, with the proviso that at least one R3 is not hydrogen.) Azastannatran having the formula:

[0017] Embodiment 10: The azastannatran of embodiment 9, having a purity of at least about 99.9%.

[0018] Embodiment 11: The azastannatran of embodiment 9 or 10, containing less than about 0.1% dialkyltin compounds.

[0019] Embodiment 12: A method for forming an azastannatrane according to any one of embodiments 9 to 11, comprising the steps of: A method comprising the step of reacting an alkyltris(dimethylamino)tin compound having the formula R1Sn(NMe2)3 with tris(2-aminoethyl)amine.

[0020] Embodiment 13: A method for forming an oxostannate membrane, comprising: providing a substrate; Coating a substrate with a solution of the stannatran according to any one of embodiments 1 to 6; drying and / or heating the coated substrate; irradiating the coated substrate; exposing the irradiated substrate to oxygen or moisture to form an oxostannate film on the substrate; A method comprising:

[0021] Embodiment 14: A method for forming an oxostannate membrane, comprising: providing a substrate; Coating a substrate with a solution of the azastannatlane according to any one of embodiments 9 to 11; drying and / or heating the coated substrate; irradiating the coated substrate; exposing the irradiated substrate to oxygen or moisture to form an oxostannate film on the substrate; A method comprising:

[0022] Embodiment 15: A method for forming an oxostannate film, comprising: vaporizing the stannatran according to any one of the first to sixth embodiments or preparing an aerosol thereof; providing a substrate; physisorbing or chemisorbing the vaporized or aerosolized stannatran onto a substrate; exposing the physisorbed or chemisorbed stannatran to a series of hydrolysis and irradiation steps, followed by oxidation or a second hydrolytic exposure to form an oxostannate film on the substrate. A method comprising:

[0023] Embodiment 16: A method for forming an oxostannate membrane, comprising: vaporizing an azastannatlane according to any one of embodiments 9 to 11 or preparing an aerosol thereof; providing a substrate; physisorbing or chemisorbing the vaporized or aerosolized azastannatrane onto a substrate; exposing the physisorbed or chemisorbed azastannatranes to a series of hydrolysis and irradiation steps, followed by oxidation or a second hydrolytic exposure to form an oxostannate film on the substrate; A method comprising:

[0024] Embodiment 17: A method for forming a patterned film comprising preparing an oxostannate film as described in embodiment 13 and exposing the film to non-continuous radiation by rastering with an electron beam or laser or by lithographic masking.

[0025] Embodiment 18: A method for forming a patterned film, comprising preparing an oxostannate film as described in embodiment 14 and exposing the film to non-continuous radiation by rastering with an electron beam or laser or by lithographic masking.

[0026] Embodiment 19: A method for forming a patterned film, comprising preparing an oxostannate film as described in embodiment 15 and exposing the film to non-continuous radiation by rastering with an electron beam or laser or by lithographic masking.

[0027] Embodiment 20: A method for forming a patterned film, comprising preparing an oxostannate film as described in embodiment 16 and exposing the film to non-continuous radiation by rastering with an electron beam or laser or by lithographic masking.

[0028] Embodiment 21: A method for forming a continuous film comprising preparing an oxostannate film as described in embodiment 13 and exposing the film to a blanket exposure utilizing an appropriate lithographic mask to obtain an optically transparent tin oxide conductive film.

[0029] Embodiment 22: A method for forming a continuous film comprising preparing an oxostannate film as described in embodiment 14 and exposing the film to a blanket exposure utilizing an appropriate lithographic mask to obtain an optically transparent tin oxide conductive film.

[0030] Embodiment 23: A method for forming a continuous film comprising preparing an oxostannate film as described in embodiment 15 and exposing the film to a blanket exposure utilizing an appropriate lithographic mask to obtain an optically transparent tin oxide conductive film.

[0031] Embodiment 24: A method for forming a continuous film comprising preparing an oxostannate film as described in embodiment 16 and exposing the film to a blanket exposure utilizing an appropriate lithographic mask to obtain an optically transparent tin oxide conductive film.

[0032] The following detailed description of the preferred embodiments of the invention will be better understood when read in conjunction with the accompanying drawings, in which: For the purpose of illustrating the invention, there are shown in the drawings embodiments which are presently preferred, it being understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown. [Brief description of the drawings]

[0033] [Figure 1a] FIG. 1a shows an XPS spectrum of a silicon wafer coated with 1-n-butyl-3,7,10-trimethyl-2,8,9-trioxa-5-aza-1-stannabicyclo[3.3.3]undecane according to one embodiment of the present disclosure. [Figure 1b] FIG. 1b shows an XPS spectrum of a silicon wafer coated with 1-n-butyl-3,7,10-trimethyl-2,8,9-trioxa-5-aza-1-stannabicyclo[3.3.3]undecane in accordance with another embodiment of the present disclosure. [Figure 2a] FIG. 2a shows an XPS spectrum of a silicon wafer coated with 1-iso-propyl-3,7,10-trimethyl-2,8,9-trioxa-5-aza-1-stannabicyclo[3.3.3]undecane according to one embodiment of the present disclosure. [Figure 2b]FIG. 2b shows an XPS spectrum of a silicon wafer coated with 1-iso-propyl-3,7,10-trimethyl-2,8,9-trioxa-5-aza-1-stannabicyclo[3.3.3]undecane in accordance with another embodiment of the present disclosure. [Figure 3a] FIG. 3a shows an XPS spectrum of a silicon wafer coated with 1-(3,3,3-trifluoropropyl)-3,7,10-trimethyl-2,8,9-trioxa-5-aza-1-stannabicyclo[3.3.3]undecane according to one embodiment of the present disclosure. [Figure 3b] FIG. 3b shows an XPS spectrum of a silicon wafer coated with 1-(3,3,3-trifluoropropyl)-3,7,10-trimethyl-2,8,9-trioxa-5-aza-1-stannabicyclo[3.3.3]undecane in accordance with another embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0034] Aspects of the present disclosure relate to a method for preparing soluble, high purity cyclic tin compounds that can be used to prepare high density tin oxide nanostructured materials by first forming an organotin film, and then optionally converting it to an inorganic thin film by drying with heating and / or exposing it to UV light, EUV light, or electron beam radiation. The resulting films have high optical density and reduced volatile by-products that are inherent to other tin precursors or that are associated with dialkyltin species that are formed as by-products during the deposition process. The volatile by-products of concern eliminated herein volatilize during processing, but adsorb onto the surfaces of chambers, exposures, and process-related equipment, causing downtime and / or loss of feature definition. The generation of these impurities is associated with the Kocheshkov rearrangement of alkyltin compounds.

[0035] More specifically, the present disclosure relates to two classes of cyclic tin compounds, trioxa-aza-1-stannabicyclo-[3.3.3]-undecanes, more conveniently referred to as stannatranes, and tetraaza-1-stannabicyclo-[3.3.3]undecanes, more conveniently referred to as azastannatranes. These cyclic tin compounds are resistant to Kocheshkov rearrangement, and no generation of dialkyltin impurities is observed during the synthesis, purification, or deposition of these compounds to form oxostannate films. These cyclic tin compounds are stable at room temperature, but can react with solid substrates as vapors or aerosols, or can be deposited on substrates from solution. Upon subsequent exposure to UV radiation, especially extreme UV radiation, these compounds lose their organic substituents to form oxostannate films that resist shrinkage. The films can be patterned by controlled exposure by rastering with an electron beam or laser, or converted by blanket conversion using an appropriate lithographic mask to yield optically transparent tin oxide conductive films. In the structural formulas shown throughout this disclosure, bonds between tertiary nitrogens are usually considered to be coordinate bonds, but may be shown as either coordinate or covalent bonds.

[0036] Stannatran and azastannatran Stannatranes according to embodiments of the present disclosure have the general formula (I): [ka] has.

[0037] In formula (I), R1 is a substituted or unsubstituted, linear or branched alkyl group having 1 to about 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to about 20 carbon atoms, or a substituted or unsubstituted alkenyl group having 2 to about 10 carbon atoms, with preferred R1 groups including methyl, ethyl, n-propyl, isopropyl, and n-butyl. Each R2 is independently hydrogen or a substituted or unsubstituted, linear or branched alkyl group having 1 to about 10 carbon atoms, with the proviso that at least one R2 is not hydrogen. Preferably, each R2 is an alkyl group, most preferably a methyl group. When R1 and / or R2 are substituted, they may be substituted with one or more halogen atoms (including partial or complete halogenation, such as chloro, bromo, fluoro, or iodo), or a trimethylsilyl group.

[0038] Exemplary stannatranes include 1-n-butyl-3,7,10-trimethyl-2,8,9-trioxa-5-aza-1-stannabicyclo[3.3.3]undecane, 1-(3,3,3-trifluoropropyl)-3,7,10-trimethyl-2,8,9-trioxa-5-aza-1-stannabicyclo[3.3.3]undecane, and 1-isopropyl-3,7,10-trimethyl-2,8,9-trioxa-5-aza-1-stannabicyclo[3.3.3]undecane, as shown below. [ka]

[0039] Azastannatranes according to embodiments of the present disclosure have the general formula (II): [ka] has.

[0040] In formula (II), R1 is a substituted or unsubstituted, linear or branched alkyl group having 1 to about 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to about 20 carbon atoms, or a substituted or unsubstituted alkenyl group having 2 to about 10 carbon atoms, with preferred R1 groups including methyl, ethyl, n-propyl, isopropyl, and n-butyl. Each R2 is independently hydrogen or a substituted or unsubstituted, linear or branched alkyl group having 1 to about 10 carbon atoms. Each R3 is independently hydrogen or a substituted or unsubstituted, linear or branched alkyl group having 1 to about 10 carbon atoms, with the proviso that at least one R3 is not hydrogen. Preferably, each R2 and R3 is an alkyl group, most preferably a methyl group. When R1 and / or R2 and / or R3 are substituted, they may be substituted with one or more halogen atoms (including partial or complete halogenation, such as chloro, bromo, fluoro, or iodo), or a trimethylsilyl group.

[0041] An exemplary azastannatrane is 1-isopropyl-2,5,8,9-tetraaza-1-stannabicyclo[3.3.3]undecane, shown below. [ka]

[0042] In preferred compounds having formulas (I) and (II), the CH2CH2 groups bridging the oxygen and nitrogen atoms are substituted, i.e., R2 in formula (I) and R3 in formula (II) are alkyl groups, preferably methyl. These compounds are preferred because they have lower melting points and greater solubility than their unsubstituted analogues. To be effective in EUV or other deposition processes, the most preferred R1 substituents are alkyl groups with two or more carbons, such as ethyl, isopropyl, or n-butyl.

[0043] The stannatranes and azastannatranes according to embodiments of the present disclosure exhibit thermal and storage stability either neat or in solution. Specifically, no decomposition was observed in solutions of the compounds described herein after 8 hours of UV light exposure or after 1 week of heating at 35° C. Furthermore, when the stannatranes or azastannatranes are synthesized as mixtures of cis and trans isomers, which can be separated and characterized, such isomeric mixtures are also stable.

[0044] The stannatranes and azastannatranes described herein are, for example, 119 They have high purity, greater than 98%, greater than 99%, greater than 99.5%, greater than 99.7%, greater than 99.8%, greater than 99.9%, or even higher, as measured by known analytical methods such as Sn NMR. In particular, the stannatranes and azastannatranes contain low levels (e.g., less than 2%, less than 1%, less than 0.5%, less than 0.3%, less than 0.2%, less than 0.1%, or lower) of dialkyltin impurities, such as dialkylbis(dimethylamino)stannanes, among others. For purposes of purity analysis, diastereomers of the compounds described herein may be considered to be the same compound.

[0045] method According to an aspect of the present disclosure, a method for making stannatranes having formula (I) includes alkoxylation of an alkyltin halide. Specifically, one method according to the present disclosure includes reacting an alkali metal alkoxide with triisopropanolamine and an alkyltin trichloride having formula R1SnCl3. Suitable reaction conditions can be determined by routine experimentation involving the particular solvent, which can be protic or aprotic. In a preferred embodiment, the method includes combining triisopropanolamine (preferably in a solvent such as methanol) with an excess of an alkali metal alkoxide, such as sodium methoxide, preferably in a solvent such as methanol or triethylamine. Then, an alkyltin trichloride (or other alkyltin halide) is added to the reaction mixture in a solvent (such as in toluene) such that the alkyltin trichloride is added in a 1:1 molar ratio to the triisopropanolamine. The reaction temperature is controlled to less than about 60°C, preferably about 20°C to about 60°C, etc. After completion of the reaction ( 119 Sn NMR), and the product is purified by known methods such as fractional distillation.

[0046] The second method includes reacting an alkyltris(dimethylamino)tin compound having the formula R1Sn(NMe2)3 with triisopropanolamine. Suitable reaction conditions can be determined by routine experimentation, including the particular solvent, which is preferably a protic solvent such as hexane or toluene, or an aprotic solvent such as THF. In a preferred embodiment, the method includes combining an alkyltris(dimethylamino)tin compound with triisopropanolamine (preferably in a solvent such as toluene) such that the alkyltris(dimethylamino)tin compound and triisopropanolamine are combined in a 1:1 molar ratio. The reaction temperature is controlled to less than about 60°C, preferably about 20°C to about 60°C, etc. After completion of the reaction ( 119 Sn NMR), and the product is purified by known methods such as fractional distillation.

[0047] According to another aspect of the present disclosure, a method for making an azastannatran having formula (II) comprises transamination of an organostannylamine. Specifically, an azastannatran having formula (II) can be prepared by reacting an alkyltris(dimethylamino)tin compound having formula R1Sn(NMe2)3 with tris(2-aminoethyl)amine. Suitable reaction conditions can be determined by routine experimentation, including the particular solvent, which is preferably a protic solvent such as hexane or toluene, or an aprotic solvent such as THF. In a preferred embodiment, the method comprises combining an alkyltris(dimethylamino)tin compound with tris(2-aminoethyl)amine (preferably in a solvent such as toluene) such that the alkyltris(dimethylamino)tin compound and tris(2-aminoethyl)amine are combined in a 1:1 molar ratio. The reaction temperature is controlled to be less than about 60° C., preferably about 20° C. to about 60° C., or the like. After completion of the reaction ( 119 Sn NMR), and the product is purified by known methods such as fractional distillation.

[0048] film Oxostannate films prepared from the stannatrane and azastannatrane compounds described herein are resistant to shrinkage during conversion into patterned structures or have reduced stress cracking of continuous films. They also have optical transmission of greater than 80% in the visible wavelength region and can form films with sufficient electrical conductivity to form electrodes.

[0049] The oxostannate films described herein may alternatively be described as SnO:H films. The films may be patterned by controlled exposure by rastering with an electron beam or laser, or may be converted in blanket conversion utilizing an appropriate lithographic mask to yield optically transparent fluorine-doped tin oxide conductive films.

[0050] A method for forming an oxostannatolane film according to an embodiment of the present disclosure includes the steps of vaporizing or providing an aerosol of a stannatolane compound having formula (I) or an azastannatolane compound having formula (II), providing a substrate, physisorbing or chemisorbing the vaporized or aerosolized stannatolane or azastannatolane onto the substrate, and exposing the physisorbed or chemisorbed stannatolane or azastannatolane to a series of hydrolysis and irradiation steps, followed by oxidation or a second hydrolytic exposure to form an oxostannatolane film on the substrate. The resulting film has high purity and is free of dialkyltin compound contamination. Each of these steps is described in more detail below.

[0051] In a first method step, the stannatrane or azastannatrane is vaporized or aerosolized by entrainment in a carrier gas such as nitrogen or argon, or by volatilization in a vacuum at a suitable temperature, and then transported to the substrate. Any type of substrate known in the art on which it is desired to form a film is suitable, such as, but not limited to, substrates containing one or more metal layers, insulating materials, semiconductor materials, or combinations thereof, including, for example, oxides, nitrides, and polysilicon materials.

[0052] The vaporized or aerosolized precursors are then physisorbed or chemisorbed onto a substrate using standard techniques associated with CVD, ALD, or similar deposition processes.

[0053] The physisorbed or chemisorbed tin compounds are then pulsed with water (preferably as steam) to remove hydrolytically unstable substituents and replace them with hydroxyl groups (hydrolysis) to form an organostannasesquioxane (organotin oxide hydroxide) coating. In a subsequent step (irradiation), the adsorbed coating is exposed to radiation (preferably EUV) at a wavelength that breaks the Sn-C bonds. Approximately 50 mJ / cm 2 , more preferably 10 mJ / cm 2Irradiation with a maximum energy level of less than 1000 nm is utilized to avoid damage to the substrate. Eventually, all of the Sn-C bonds are replaced with Sn-O bonds, which are formed simultaneously with or after irradiation by exposure to oxygen or water in the ambient air.

[0054] In particular, strong absorption of extreme ultraviolet light associated with tin is observed at 13.5 nm. Most organic moieties bonded to tin have strong absorption of ultraviolet light at wavelengths of 193 nm and relatively strong absorption up to 230 nm. Therefore, suitable wavelengths of irradiation are in the range of 13.5 to 280 nm, including EUV and deep UV. Upon sufficient energy absorption at these wavelengths, the metal-organic bond is cleaved. Simultaneously with or subsequent to the cleavage reaction, additional oxo bridges between tin atoms are formed, either by oxidation, hydrolysis, or hydroxyl substitution reactions.

[0055] A second method for forming an oxostannate film according to an embodiment of the present disclosure includes providing a substrate, coating the substrate with a solution of a stannatrane having formula (I) or an azastannatrane having formula (II), drying and / or heating the coated substrate, irradiating the coated substrate, and exposing the irradiated film to oxidation or water / moisture in the ambient air to form an oxostannate film on the substrate. The resulting film has high purity and is free of dialkyltin compound contamination.

[0056] Suitable substrates have been described previously. A solution of the stannatran or azastannatran may be prepared in any solvent known or to be developed in the art, for example, an alcohol, such as ethanol, which is currently preferred, or an aprotic solvent, such as THF. The concentration of the stannatran or azastannatran in the solvent may be determined by routine experimentation, but may be, for example, about 50-20% by weight, preferably about 10-15% by weight. Any known method for applying the solution to a substrate may be used, such as, for example, dip coating or spin-on techniques.

[0057] The coated substrate is dried at room temperature for a sufficient time, as determined by routine experimentation, such as overnight, or by heating (annealing), such as to about 100° C.-150° C., preferably about 120° C.-125° C., to effect thermal conversion. Finally, the coated substrate is irradiated as previously described and then exposed to oxygen or moisture in the ambient air to form the oxostannate film.

[0058] Without wishing to be bound by theory, it is believed that the presently claimed method steps and the condensation process of tin-hydroxyl groups to form stannoxane bonds result in denser films, which is desirable at some levels, but may also result in shrinkage and distortion that affects the fidelity of the lithography process or induces stress cracking in continuous films. Thus, films prepared by the methods described herein achieve the goal of reducing film shrinkage after radiation exposure. However, other critical performance requirements must be met, including sufficient optical cross-section, film formation on the substrate, dose sensitivity (photosensitivity), storage stability (thermal stability), and volatile content (outgassing during exposure or inherent to the compound). Each of these requirements is described in detail below.

[0059] <High optical cross section> Tin-oxo cluster / polymer materials have proven to be promising EUV resists. In particular, a hydroxy-terminated SnOx underlayer on the surface of the substrate material enhances the absorption of radiation upon irradiation of the imaging layer, and secondary electrons can be generated from the substrate to further collect additional EUV photons, making the EUV patterning process more sensitive and reducing the required EUV dose needed for imaging layer exposure. Among the elements of the periodic table, tin has a particularly high optical cross section.

[0060] <Film formation - substrate reactivity> Metal-organic (RMX3) compounds must contain a hydrolyzable ligand-metal bond, and X is a ligand with a hydrolyzable MX bond. In the compounds described herein, R is an alkyl group (R1) and X represents three nitrogen bridges or three oxygen bridges. In particular, suitable organotin compounds must be capable of forming films / polymers / clusters on the wafer surface by CVD, ALD, or spin-on. If the application or deposition is a condensed phase spin-on, clusters may be formed in the liquid precursor prior to deposition, but this typically causes greater shrinkage.

[0061] <Dose sensitivity (photosensitivity)> The R group of the cyclic tin compound is believed to play an important role in the UV sensitivity of the EUV resist material, since the SnOx thin film imaging layers containing or terminated with alkyl groups are selected such that they undergo tin-carbon bond cleavage, such as beta-hydride elimination, upon irradiation with EUV light. In the EUV patterning process, the alkyl group can be cleaved, leaving areas of Sn-H bonds, while the unexposed surfaces remain alkyl terminated. The film after exposure to EUV undergoes changes, including but not limited to the loss of organic pendant substituents attached to metal atoms in the low density M-OH rich material, allowing them to crosslink to the higher density MOM-bonded metal oxide material. The Sn-H bonds, which may be described as tin hydrides, are oxidatively and hydrolytically sensitive to form oxides. The hydrolysis reaction of tin hydrides produces hydrogen, which is a volatile by-product but does not act as a contaminant.

[0062] <Storage stability> Tin compounds have a strong tendency to undergo disproportionation reactions, also called Kocheshkov proportionation reactions. This reaction accelerates with increasing temperature. Storage stability at temperatures compatible with semiconductor production lines, approximately 20-35°C, is highly desirable. Implicit in the performance of materials is the requirement of moisture reactivity, meaning moisture sensitivity. Therefore, storage stability must be considered as long as materials are supplied as manufactured goods and long-term storage is required.

[0063] <Volatile components> The tin compound must be sufficiently volatile to be transported to the substrate by the deposition process, but components that are volatile and not reactive with the substrate must be minimized as they will diffuse to non-target areas.Typical sources of these volatile components come from non-proportionation by-products formed during propagating and radiation exposure during manufacture or storage.

[0064] The present disclosure also relates to a method for forming a patterned film comprising preparing an oxostannate film as described herein and exposing the film to non-continuous radiation by rastering with an electron beam or laser or by lithographic masking.

[0065] The present disclosure also relates to a method for forming a continuous film comprising preparing an oxostannate film as described herein and exposing the film to a blanket light exposure utilizing an appropriate lithographic mask to obtain an optically transparent oxostannate conductive film.

[0066] The invention will now be described with reference to the following non-limiting examples. EXAMPLES

[0067] Example 1: Synthesis of 1-n-butyl-3,7,10-trimethyl-2,8,9-trioxa-5-aza-1-stannabicyclo[3.3.3]undecane [ka]

[0068] Under an inert atmosphere, a 2 L, four-necked, round-bottom flask equipped with a mechanical stirrer, pot thermometer, thermowell, and addition funnel was charged with 124 g (0.65 mol) of triisopropanolamine and 235 mL of methanol. 421 g (1.95 mol) of a 25% w / w solution of sodium methoxide in methanol was added to the flask. A solution of 183 g of n-BuSnCl3 (0.65 mol) in 550 mL of toluene was then added dropwise to the flask over a period of 1 hour while maintaining the pot temperature below 40° C. The progress of the reaction was monitored by 119 The reaction was monitored by Sn NMR. After completion, the reaction was stripped to a pot temperature of 120° C. and the resulting concentrate was filtered through an air-free filter. The product was purified by fractional distillation through a Vigreux column under reduced pressure (isolated at 136-9° C., 0.5 torr) to give 147 g (61%) of a thick pale yellow oil. 1 H and 119 It was identified by Sn NMR spectroscopy as a pair of diastereomers in approximately a 3:1 ratio with the properties shown in Table 1. 119 Less than 0.1% concentrations of dialkyltin species were observed by Sn NMR.

[0069] UV exposure The product was exposed to light for 8 hours and no evidence of decomposition was observed. 119 Sn or 1 No signs of decomposition of the product samples were observed in either the H NMR spectrum or the 1 H NMR spectrum. 119 Less than 0.1% concentrations of dialkyltin species were observed by Sn NMR.

[0070] heat exposure The product was exposed to heat at 35°C for one week and no evidence of decomposition was observed. 119 Sn or 1 No signs of decomposition of the product samples were observed in either the H NMR spectrum or the 1 H NMR spectrum. 119 Less than 0.1% concentrations of dialkyltin species were observed by Sn NMR.

[0071] [Table 1]

[0072] Example 2: Synthesis of 1-(3,3,3-trifluoropropyl)-3,7,10-trimethyl-2,8,9-trioxa-5-aza-1-stannabicyclo[3.3.3]undecane [ka]

[0073] Under an inert atmosphere, a 500 mL three-neck round bottom flask equipped with a magnetic stirrer, pot thermometer, thermowell, and addition funnel was charged with 38.25 g (0.20 mol) of triisopropanolamine and 73 mL of methanol. To the flask was added 130 g (0.60 mol) of a 25% w / w solution of sodium methoxide in methanol. Next, a solution of 64.42 g (0.20 mol) of CF3CH2CH2SnCl3 in 162 mL of toluene was added dropwise to the flask over 1 hour while maintaining the pot temperature below 40°C. The progress of the reaction was monitored. 119 The reaction was monitored by Sn NMR. After completion of the reaction, the reaction was stripped to a pot temperature of 120°C and the resulting concentrate was filtered through an air-free filter. The product was purified by vacuum distillation (126-128°C, isolated at 0.3 torr) to give 56.6 g (70%) of a crystalline pale yellow solid. The product was 1 H and 119 It was identified by Sn NMR spectroscopy as a pair of diastereomers in approximately a 3:1 ratio with the properties shown in Table 2. 119 Less than 0.1% concentrations of dialkyltin species were observed by Sn NMR.

[0074] UV exposure The product in saturated cyclohexane solution was exposed to light for 8 hours and no evidence of decomposition was observed. 119 Sn or 1 No signs of decomposition of the product samples were observed in either the H NMR spectrum or the 1 H NMR spectrum. 119 Less than 0.1% concentrations of dialkyltin species were observed by Sn NMR.

[0075] heat exposure The product in saturated cyclohexane solution was exposed to heat at 35°C for one week, and no evidence of decomposition was observed. 119 Sn or 1 No signs of decomposition of the product samples were observed in either the H NMR spectrum or the 1 H NMR spectrum. 119 Less than 0.1% concentrations of dialkyltin species were observed by Sn NMR.

[0076] [Table 2]

[0077] Example 3: Synthesis of 1-isopropyl-3,7,10-trimethyl-2,8,9-trioxa-5-aza-1-stannabicyclo[3.3.3]undecane [ka]

[0078] Under an inert atmosphere, 57.0 g (0.194 mol) of isopropyltris(dimethylamino)tin was placed in a 200 mL three-neck round bottom flask equipped with a magnetic stirrer, pot thermometer, thermowell, and addition funnel. A solution of 37.02 g (0.194 mol) of triisopropanolamine in 43 mL of toluene was added dropwise to the flask while maintaining the pot temperature below 40° C. The reaction was stirred for 2 hours. 119 Sn-NMR was used for monitoring. Upon completion, the product was isolated from the reaction mixture by vacuum distillation (108-110° C. at 0.3 torr) to give 41.1 g (65%) of a white crystalline solid with a melting point of 93-94° C. 1 H and 119 It was identified by Sn NMR spectroscopy as a pair of diastereomers in a ratio of about 2.5:1 with the properties shown in Table 3. 119 Less than 0.1% concentrations of dialkyltin species were observed by Sn NMR.

[0079] UV exposure The product in saturated cyclohexane solution was exposed to light for 8 hours and no evidence of decomposition was observed. 119 Sn or1 No signs of decomposition of the product samples were observed in either the H NMR spectrum or the 1 H NMR spectrum. 119 Less than 0.1% concentrations of dialkyltin species were observed by Sn NMR.

[0080] heat exposure The product in saturated cyclohexane solution was exposed to heat at 35°C for one week, and no evidence of decomposition was observed. 119 Sn or 1 No signs of decomposition of the product samples were observed in either the H NMR spectrum or the 1 H NMR spectrum. 119 Less than 0.1% concentrations of dialkyltin species were observed by Sn NMR.

[0081] [Table 3]

[0082] Example 4: Synthesis of 1-isopropyl-2,5,8,9-tetraaza-1-stannabicyclo[3.3.3]undecane [ka]

[0083] Under an inert atmosphere, 132.30 g (0.45 mol) of isopropyltris(dimethylamino)tin was placed in a 500 mL three-neck round bottom flask equipped with a magnetic stirrer, pot thermometer, thermowell, and addition funnel. A solution of 65.80 g (0.45 mol) of tris(2-aminoethyl)amine in 75.90 mL of toluene was added dropwise to the flask while maintaining the pot temperature below 40° C. The reaction was stirred for 2 hours. 119 Sn-NMR was used for monitoring. After completion (gas evolution had ceased), 90% of the solvent in the reaction mixture was removed by vacuum distillation to give a solid product mixture, and dry hexane was added to precipitate the title compound: 107.4 g (83.78%) of a pale yellow solid with a melting point of 58° C. 1 H and 119 It was confirmed by Sn NMR spectroscopy and had the properties shown in Table 4. 119Less than 0.1% concentrations of dialkyltin species were observed by Sn NMR.

[0084] [Table 4]

[0085] (Example 5: Surface modification of silicon wafer with 1-n-butyl-3,7,10-trimethyl-2,8,9-trioxa-5-aza-1-stannabicyclo[3.3.3]undecane) All operations were carried out at ambient laboratory conditions. Silicon wafers were cleaned and dried in a dry box using a hotplate set at 120°C (or room temperature). 0.20 g of 1-n-butyl-3,7,10-trimethyl-2,8,9-trioxa-5-aza-1-stannabicyclo[3.3.3]undecane as prepared in Example 1 was placed in 15.1 g of absolute EtOH and stirred at 45°C for 30 minutes. Samples were prepared in duplicate. Sample A was immersed in the solution for 5 minutes and dried at 120°C for 5 minutes, and sample B was immersed in the solution for 5 minutes and then dried at room temperature overnight. XPS spectra of samples A and B are shown in Figures 1a and 1b.

[0086] Figure 1a shows the XPS spectrum of a silicon wafer coated with 1-n-butyl-3,7,10-trimethyl-2,8,9-trioxa-5-aza-1-stannabicyclo[3.3.3]undecane after 5 min of soaking and drying at 120 °C for 5 min, and Figure 1b shows the XPS spectrum of a silicon wafer coated with 1-n-butyl-3,7,10-trimethyl-2,8,9-trioxa-5-aza-1-stannabicyclo[3.3.3]undecane after 5 min of soaking and drying at room temperature overnight. These spectra demonstrate that the oxostannate film was successfully deposited on the silicon wafer.

[0087] (Example 6: Surface modification of silicon wafer with 1-isopropyl-3,7,10-trimethyl-2,8,9-trioxa-5-aza-1-stannabicyclo[3.3.3]undecane) All operations were carried out at ambient laboratory conditions. Silicon wafers were cleaned and dried in a dry box using a hotplate set at 120°C (or room temperature). 0.20 g of 1-isopropyl-3,7,10-trimethyl-2,8,9-trioxa-5-aza-1-stannabicyclo[3.3.3]undecane as prepared in Example 3 was placed in 15.1 g of absolute EtOH and stirred at 45°C for 30 minutes. Samples were prepared in duplicate. Sample A was immersed in the solution for 5 minutes and dried at 120°C for 5 minutes, and sample B was immersed in the solution for 5 minutes and then dried at room temperature overnight. The XPS spectra of samples A and B are shown in Figures 2a and 2b.

[0088] Figure 2a shows the XPS spectrum of a silicon wafer coated with 1-isopropyl-3,7,10-trimethyl-2,8,9-trioxa-5-aza-1-stannabicyclo[3.3.3]undecane after 5 min of immersion and drying at 120 °C for 5 min, and Figure 2b shows the XPS spectrum of a silicon wafer coated with 1-isopropyl-3,7,10-trimethyl-2,8,9-trioxa-5-aza-1-stannabicyclo[3.3.3]undecane after 5 min of immersion and drying at room temperature overnight. These spectra demonstrate that the oxostannate film was successfully deposited on the silicon wafer.

[0089] (Example 7: Surface modification of silicon wafer with 1-(3,3,3-trifluoropropyl)-3,7,10-trimethyl-2,8,9-trioxa-5-aza-1-stannabicyclo[3.3.3]undecane) All operations were carried out at ambient laboratory conditions. Silicon wafers were cleaned and dried in a dry box using a hotplate set at 120°C (or room temperature). 0.20 g of 1-(3,3,3-trifluoropropyl-3,7,10-trimethyl-2,8,9-trioxa-5-aza-1-stannabicyclo[3.3.3]undecane as prepared in Example 2 was placed in 15.1 g of absolute EtOH and stirred at 45°C for 30 minutes. Samples were prepared in duplicate. Sample A was immersed in the solution for 5 minutes and dried at 120°C for 5 minutes, and Sample B was immersed in the solution for 5 minutes and then dried at room temperature overnight. The XPS spectra of Samples A and B are shown in Figures 3a and 3b.

[0090] Figure 3a shows the XPS spectrum of a silicon wafer coated with 1-(3,3,3-trifluoropropyl-3,7,10-trimethyl-2,8,9-trioxa-5-aza-1-stannabicyclo[3.3.3]undecane after 5 min of immersion and drying at 120 °C for 5 min, and Figure 3b shows the XPS spectrum of a silicon wafer coated with 1-(3,3,3-trifluoropropyl)-3,7,10-trimethyl-2,8,9-trioxa-5-aza-1-stannabicyclo[3.3.3]undecane after 5 min of immersion and drying at room temperature overnight. These spectra demonstrate that the oxostannate film was successfully deposited on the silicon wafer.

[0091] It will be appreciated by those skilled in the art that changes may be made to the above-described embodiments without departing from the broad inventive concept thereof. It is understood, therefore, that this invention is not limited to the particular embodiments disclosed, but is intended to cover modifications within the spirit and scope of the invention as defined by the appended claims.

Claims

1. Formula (I): 【Chemistry 1】 (In the formula, R １ is a substituted or unsubstituted, linear or branched alkyl group having 1 to about 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to about 20 carbon atoms, or a substituted or unsubstituted alkenyl group having 2 to about 10 carbon atoms; ２ are independently hydrogen or a substituted or unsubstituted, linear or branched alkyl group having 1 to about 10 carbon atoms, provided that at least one R ２ is not hydrogen) A stannatran having the formula:

2. Formula 1-n-butyl-3,7,10-trimethyl-2,8,9-trioxa-5-aza-1-stannabicyclo[3.3.3]undecane: 【Chemistry 2】 The stannatran of claim 1 having the formula:

3. Formula 1-(3,3,3-trifluoropropyl)-3,7,10-trimethyl-2,8,9-trioxa-5-aza-1-stannabicyclo[3.3.3]undecane: 【Chemistry 3】 The stannatran of claim 1 having the formula:

4. Formula 1-isopropyl-3,7,10-trimethyl-2,8,9-trioxa-5-aza-1-stannabicyclo[3.3.3]undecane: 【Chemistry 4】 The stannatran of claim 1 having the formula:

5. 5. The stannatran according to any one of claims 1 to 4, having a purity of at least about 99.9%.

6. 6. The stannatran of any one of claims 1 to 5, containing less than about 0.1% dialkyltin compounds.

7. A method for forming the stannatran according to any one of claims 1 to 6, comprising the steps of: An alkali metal alkoxide is reacted with triisopropanolamine and a compound of formula R １ SnCl ３ with an alkyltin trichloride compound having the formula:

8. A method for forming the stannatran according to any one of claims 1 to 6, comprising the steps of: Formula R １ Sn(NMe ２ ) ３ 1. A method comprising the step of reacting an alkyltris(dimethylamino)tin compound having the formula:

9. Formula (II): 【Chemistry 5】 (In the formula, R １ is a substituted or unsubstituted, linear or branched alkyl group having 1 to about 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to about 20 carbon atoms, or a substituted or unsubstituted alkenyl group having 2 to about 10 carbon atoms; ２ are independently hydrogen or a substituted or unsubstituted, linear or branched alkyl group having from 1 to about 10 carbon atoms; ３ are independently hydrogen or a substituted or unsubstituted, linear or branched alkyl group having 1 to about 10 carbon atoms, provided that at least one R ３ is not hydrogen) Azastannatran having the formula:

10. 10. The azastannatran of claim 9 having a purity of at least about 99.9%.

11. 11. The azastannatrane of claim 9 or 10, containing less than about 0.1% dialkyltin compounds.

12. 12. A method for forming an azastannatrane according to any one of claims 9 to 11, comprising the steps of: Formula R １ Sn(NMe ２ ) ３ 2. A method for producing a tin compound comprising the steps of: reacting an alkyltris(dimethylamino)tin compound having the formula: with tris(2-aminoethyl)amine.

13. 1. A method for forming an oxostannate film, comprising: providing a substrate; Coating a substrate with a solution of a stannatran according to any one of claims 1 to 6; drying and / or heating the coated substrate; irradiating the coated substrate; exposing the irradiated substrate to oxygen or moisture to form an oxostannate film on the substrate; A method comprising:

14. 1. A method for forming an oxostannate film, comprising: providing a substrate; Coating a substrate with a solution of an azastannatlane according to any one of claims 9 to 11; drying and / or heating the coated substrate; irradiating the coated substrate; exposing the irradiated substrate to oxygen or moisture to form an oxostannate film on the substrate; A method comprising:

15. 1. A method for forming an oxostannate film, comprising: Vaporizing a stannatran according to any one of claims 1 to 6 or preparing an aerosol thereof; providing a substrate; physisorbing or chemisorbing the vaporized or aerosolized stannatran onto a substrate; exposing the physisorbed or chemisorbed stannatran to a series of hydrolysis and irradiation steps, followed by oxidation or a second hydrolytic exposure to form an oxostannate film on the substrate; A method comprising:

16. 1. A method for forming an oxostannate film, comprising: vaporizing an azastannatlane according to any one of claims 9 to 11 or providing an aerosol thereof; providing a substrate; physisorbing or chemisorbing the vaporized or aerosolized azastannatrane onto a substrate; exposing the physisorbed or chemisorbed azastannatranes to a series of hydrolysis and irradiation steps, followed by oxidation or a second hydrolytic exposure to form an oxostannate film on the substrate; A method comprising:

17. 14. A method for forming a patterned film, comprising the steps of preparing an oxostannate film as defined in claim 13 and exposing the film to non-continuous radiation by rastering with an electron beam or laser or by lithographic masking.

18. 15. A method for forming a patterned film, comprising the steps of preparing an oxostannate film as defined in claim 14 and exposing the film to non-continuous radiation by rastering with an electron beam or laser or by lithographic masking.

19. 20. A method for forming a patterned film comprising the steps of preparing an oxostannate film as defined in claim 15 and exposing the film to non-continuous radiation by rastering with an electron beam or laser or by lithographic masking.

20. 20. A method for forming a patterned film comprising the steps of preparing an oxostannate film as defined in claim 16 and exposing the film to non-continuous radiation by rastering with an electron beam or laser or by lithographic masking.

21. 14. A method for forming a continuous film, comprising the steps of preparing an oxostannate film as defined in claim 13 and exposing the film to a blanket exposure utilizing an appropriate lithographic mask to obtain an optically transparent tin oxide conductive film.

22. 15. A method for forming a continuous film, comprising the steps of preparing an oxostannate film as defined in claim 14 and exposing the film to a blanket exposure utilizing an appropriate lithographic mask to obtain an optically transparent tin oxide conductive film.

23. 20. A method for forming a continuous film, comprising the steps of preparing an oxostannate film as defined in claim 15 and exposing the film to a blanket exposure utilizing an appropriate lithographic mask to obtain an optically transparent tin oxide conductive film.

24. 20. A method for forming a continuous film, comprising the steps of preparing an oxostannate film as defined in claim 16 and exposing the film to a blanket exposure utilizing an appropriate lithographic mask to obtain an optically transparent tin oxide conductive film.

Images