Process for the preparation of organotin compounds

Abstract

The invention provides an efficient and effective process for preparing certain organotin compounds having alkyl and alkylamino substituents. The process provides organotin compounds in high purity crystalline form that are particularly suitable for use as precursors for depositing high purity tin oxide films in, for example, extreme ultraviolet (EUV) photolithography techniques used in the manufacture of certain microelectronic devices.

Description

Technical Field

[0001] This invention belongs to the field of organotin chemistry. Specifically, it relates to an efficient and effective method for preparing certain organotin compounds, such as isopropyltris(dimethylamino)tin. Background Technology

[0002] Certain organotin compounds have been demonstrated to be suitable for depositing high-purity tin(II) oxide in applications such as extreme ultraviolet (EUV) lithography used in the manufacture of certain microelectronic devices. Organotin compounds with combinations of alkylamino and alkyl groups are of particular interest, as they may be difficult to obtain in high purity.

[0003] Therefore, there is a need to provide an improved method for manufacturing such organotin compounds in high-purity form for depositing high-purity tin oxide films. Summary of the Invention

[0004] This document provides a method for preparing certain organotin compounds having alkyl and alkylamino substituents, such as compounds of formula (I): R1-Sn-(NR2)3, wherein the same or different Rs are C1-C4 alkyl groups and R1 is a substituted or unsubstituted saturated or unsaturated straight-chain, branched, or cyclic C1-C5 group. A specific example of a compound of formula (I) is isopropyltris(dimethylamino)tin (CAS No. 1913978-89-8). The method comprises contacting a compound of formula (A), which is described more specifically herein, with a compound of formula R1-X wherein X is bromine, iodine, or chlorine. The method also produces a compound of formula (II), and the invention also relates to this compound. Advantageously, the method provides organotin precursor compounds of formula (I) in a high-purity form (e.g., greater than 98% purity). Due to their high purity, the organotin compounds described herein are particularly suitable for depositing high-purity tin oxide (SnOx) films in extreme ultraviolet (EUV) lithography techniques used, for example, in the manufacture of microelectronic devices. Attached Figure Description

[0005] Figure 1 This is a crystal structure drawing of compound (II) as a byproduct of the method described herein, wherein each R is a methyl group and each X is an iodine group.

[0006] Figure 2A and Figure 2B The compounds of formula (I) are obtained separately from d6-benzene as products of the methods described herein. 119 Sn-NMR and 1 H-NMR spectra, where each R represents methyl and R1 represents isopropyl. Detailed Implementation

[0007] This invention relates to a method for preparing organotin compounds having alkyl and alkylamino substituents.

[0008] In a first embodiment, the present invention provides a method for preparing monoalkyltris(dialkylamino)tin compounds of formula (I):

[0009]

[0010] In this formula, each R can be the same or different and is a C1-C4 alkyl group, and R1 is a substituted or unsubstituted saturated or unsaturated straight-chain, branched, or cyclic C1-C5 group. The method comprises using a compound of formula (A).

[0011]

[0012] Contact with compounds having the formula R1-X, where X is bromine, iodine, or chlorine. In one embodiment of this method, each R can be independently selected from methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, tert-butyl, and sec-butyl. In a particular embodiment, each R is methyl. Furthermore, R1 can be selected from methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, tert-butyl, sec-butyl, n-pentyl, isopentyl, or neopentyl. Additionally, R1 can be a cyclic C1-C5 group, such as cyclopropyl. Furthermore, R1 can be an unsaturated C1-C5 group, such as vinyl or ethynyl. Any of these R1 groups can be further substituted, for example, by one or more halogen or ether groups. For example, R1 can be having the formula -(CH2). n (CH a F b ) m The fluorinated alkyl group, wherein m = 1 to 5 and m+n = 1 to 5 and wherein b = 1 to 3 and a+b = 3, includes monofluorinated C1-C5 alkyl groups (e.g., -CH2F or -CH2CH2F groups) and perfluorinated C1-C5 groups (e.g., -CF3 or CF2CF3 groups). Alternatively, R1 may be an alkyl ether group, wherein the alkyl portion is C1-C5 alkyl. In a particular embodiment, R1 is an unsubstituted C1-C5 alkyl group, such as a C1-C3 alkyl group. For example, each R may be methyl and R1 may be isopropyl.

[0013] As shown above, the starting material used in this method is compound of formula (A):

[0014]

[0015] This compound can be prepared by known methods, for example by reacting tin(II) chloride (SnCl2) with a compound of formula MN(R)2, wherein M is a metal selected from sodium, lithium, and potassium. Therefore, one embodiment of the invention is a method for preparing a compound of formula (I), which further comprises the prior step of preparing a starting material of formula (A) by reacting tin(II) chloride with a compound of formula MN(R)2, wherein M is a metal cation, such as an Al cation, Mg cation, or Ca cation; or a Group 1 or Group 2 cation, such as a sodium ion, lithium ion, or potassium ion. As a specific example, M may be a lithium ion and R may be a methyl group. In such cases, the lithium chloride thus formed may be removed, for example, by filtration (if necessary), followed by contacting the resulting compound of formula (A) with compounds of formulas R1-X. In other cases, the resulting starting material compound of formula (A) may be used as is in slurry form without filtration, and reacted in the same reaction vessel as a precipitated compound of formula M-Cl (e.g., lithium chloride). Therefore, the method of the present invention provides a one-pot synthesis of compounds of formula (I).

[0016] The reaction provides a mixture of the compound of formula (I) as shown above and the byproduct of formula (II):

[0017]

[0018] In this compound, each R may be the same or different and is a C1-C4 alkyl group, and each X is selected from iodine, bromine, and chlorine. Therefore, the present invention further provides byproduct compounds of formula (II). For example, in one embodiment of this byproduct, each R may be the same or different and is a C1-C4 alkyl group, and each X is selected from iodine, bromine, and chlorine, provided that when X is chlorine, R is not methyl. In another embodiment, each R may be the same or different and is a C1-C4 alkyl group, and each X is iodine or bromine. The crystal structure of the compound of formula (II) is depicted on [the diagram / image ... Figure 1 In the formula (II), each R is methyl and each X is iodine. It is also anticipated that the byproducts of these formulas (II) are suitable as precursor compounds for depositing tin oxide films (e.g., tin oxide (II) or tin oxide (IV) films), and as intermediates in the synthesis of other useful organotin precursor compounds.

[0019] The method of the present invention can be carried out in its pure form (i.e., without any added solvent) or in a solvent that is not originally reactive with the starting material or product. Examples of suitable solvents are nonpolar aprotic solvents, including liquid hydrocarbons such as hexane, benzene, or toluene; polar aprotic solvents such as tetrahydrofuran or dimethoxyethane; and mixtures of nonpolar aprotic solvents and polar aprotic solvents. When carried out in its pure form without any added solvent, an excess of the compound of formula R1-X can be used, especially when this compound is liquid. Furthermore, the method can be carried out by an exchange reaction using a combination of a halogen exchange reagent and a compound of formula R1-X.

[0020] The method is carried out at a temperature suitable for the reaction of the disclosed reactants. For example, the reaction temperature may be in the range of near room temperature (e.g., about 20°C) to about 80°C. In a preferred embodiment, the method is carried out at a temperature of room temperature (23°C) to about 65°C, for example, from about 50°C to about 70°C or about 60°C.

[0021] As noted above, in the synthesis of the starting material of formula (A), lithium halide byproducts (e.g., LiCl) can be removed by filtration. The resulting starting material can be used as is in the same reaction vessel for further reaction with compounds of formula R1-X to form compounds of formula (I), which can be further purified, for example, by distillation, to provide a product with a lower content of impurities.

[0022] The invention can be further illustrated by the embodiments included herein, but it will be understood that, unless otherwise specifically indicated, these embodiments are included for illustrative purposes only and are not intended to limit the scope of the invention.

[0023] Example 1

[0024] Isopropyltris(dimethylamino)tin was prepared using the reaction sequence described above and shown below:

[0025]

[0026] Therefore, 12.2 g of lithium dimethylamino (239 mmol) and 250 mL of hexane were added to a 500 mL round-bottom flask with a three-necked neck and equipped with a magnetic stir bar. 21.6 g of SnCl2 (113 mmol) was added to this grayish-white slurry, and the mixture was stirred at 60 °C for 72 hours. The resulting grayish-green slurry was cooled to 23 °C to obtain a mixture including the compound of formula (A).

[0027] Without further purification, the mixture was treated with 11.5 g of 2-iodopropane (68.2 mmol). The reaction mixture was then heated to 60 °C for 18 hours. After cooling to 23 °C, the reaction mixture was filtered through a coarse-pore sintered filter into a 500 mL flask, and the filter cake was washed with 500 mL of anhydrous hexane aliquots to give a pale yellow, clear solution. The solvent and other volatiles were then removed from the filtrate under reduced pressure to produce a mixture of product (I) and byproduct (II).

[0028] Once the volatile matter removal was complete, the remaining oily residue was filtered through a 0.2-micron syringe filter to obtain 10.6 g of orange oily residue. The orange oily residue was placed in a -30°C freezer overnight, causing [ISn(NMe2)]2 to precipitate as a yellow solid. This yellow solid was removed by filtration through a 0.2-micron syringe filter. Subsequently, the remaining orange oily residue was distilled using short-path distillation at 610-645 mTorr with a top temperature of 34-37°C to obtain isopropyltris(dimethylamino)tin (6.09 g, 36.5%) as a clear, pale yellow-green oil distillate. 1 H-NMR (400MHz, benzene-d6): δ2.83 ( 1 H- 119 / 117 Sn)=20.8Hz,18H),1.68-1.57(m,1H),1.27(d,J1h-13C=7.3Hz,6H). 119 Sn NMR: 64.30. Figure 2A and 2B The middle section shows 119 Sn-NMR and 1 The H-NMR spectrum indicates that the product has high purity.

[0029] The byproduct [ISn(NMe2)]2 was found to be a crystalline solid and therefore possessed high purity, for example, greater than 95%, including greater than 98%, 99%, or 99.5%. The crystal structure is shown in... Figure 1 The crystallinity data are provided in Tables 1 and 2. Due to their high purity, these organotin compounds are expected to be suitable for depositing high-purity tin oxide films in extreme ultraviolet (EUV) lithography techniques used, for example, in the manufacture of microelectronic devices.

[0030] Table 1 - [ISn(NMe)] 2 )] Crystal data and structural refinement of 2.

[0031]

[0032]

[0033] Table 2 - [ISn(NMe)] 2 )] 2 bond length Bond angle [°]

[0034]

[0035]

[0036] Example 2

[0037] F3CSn(NMe2)3 was prepared using the reaction sequence described in Example 1. Specifically, [Sn(NMe2)2]2 (23.1 g, 55.6 mmol) was placed in a 250 mL round-bottom flask equipped with a magnetic stir bar and dissolved in hexane (125 mL). The flask was fitted with a gas cylinder containing I-CF3 (25 g, 127.6 mmol) via a 1 / 4 PTFE tube and a 24 / 40 tube adapter. The I-CF3 was slowly bubbled into the hexane solution with stirring in the dark. After approximately 10 minutes, a yellow precipitate was formed. After approximately 30 minutes, all the gas was added, and a flocculent yellow precipitate was formed. The gas cylinder was then removed and a mass measurement was performed to confirm that all the required I-CF3 had been added. The reactants were covered with foil and stirred over the weekend in the dark at room temperature. Subsequently, the reaction produced a yellow / brown precipitate, which was filtered through a disposable polyethylene porous glass filter and washed with hexane (25 mL). The resulting pale yellow solution was dried under reduced pressure until approximately 5 mL remained. The product's C6D6 solution... 1 H-NMR, 19 F-NMR and 119 Sn-NMR showed that hexane (approximately 5 mol) remained. A brownish solid (28.7 g) and a pale yellow liquid (4 g, 22.5%) were separated. 1 H-NMR(C6D6,400MHz);s,18H,2.69ppm; 119 Sn-NMR(C6D6,150MHz); q,-153.07ppm; 19 F-NMR (C6D6, 376MHz); -42.7ppm.

[0038] Example 3

[0039] F3CCH2Sn(NMe2)3 was prepared using a procedure similar to that shown in Example 2. Specifically, [Sn(NMe2)2]2 (140 g, 336 mmol) was placed in a 1 L Schlenk flask equipped with a magnetic stir bar and diluted with approximately 400 mL of hexane to form a yellow mixture. I-CH2-CF3 was placed in a 250 mL feeding funnel and connected to the Schlenk flask. A slow addition rate (approximately 0.5–1 drop / second) was achieved, and the 1 L flask was covered with aluminum foil and stirred in the dark. After approximately 2.5 hours, the addition of I-CH2CF3 was completed, and the resulting yellow mixture was stirred overnight in the dark at room temperature. Subsequently, the reaction produced a bright yellow solid precipitate and a red / orange solution. The precipitate was separated into a 500 mL Schlenk flask equipped with a magnetic stir bar by filtration through a disposable polyethylene porous glass filter. The filter cake was washed with hexane (approximately 30 mL), and the resulting orange solution was dried under reduced pressure to give a pale yellow solution with a yellow precipitate. The mixture was filtered through a 0.2 μm syringe filter into two amber 40 mL reconstitution vials to give 87.91 g (78.5% crude yield) of the product as a pale yellow liquid. A 1:1 product:C6D6 solution was then used. 1 H-NMR, 19 F-NMR and 119 Sn-NMR results: 1 H-NMR (C6D6, 400MHz); s, 18H, 2.66ppm; q, 2H, 1.52ppm; 119 Sn-NMR(C6D6,150MHz); q,-62.47ppm; 19 F-NMR (C6D6, 376MHz); q, -51.93ppm.

[0040] The invention has been described in detail with particular reference to certain embodiments thereof, but it will be understood that variations and modifications may be made within the spirit and scope of the invention.

Claims

1. A method for preparing monoalkyltris(dialkylamino)tin compounds of formula (I), Wherein each R is the same or different and is a C1-C4 alkyl group, and R1 is a substituted or unsubstituted saturated or unsaturated straight-chain, branched or cyclic C1-C5 group, wherein when R1 is substituted, it is substituted by one or more halogen or ether groups; wherein the method comprises: Compound (A) Contact with a compound of formula R1-X, where X is bromine, iodine or chlorine.

2. The method according to claim 1, wherein each R is independently methyl, ethyl, propyl, n-butyl, isobutyl, tert-butyl, or sec-butyl.

3. The method according to claim 2, wherein the propyl group is isopropyl.

4. The method according to claim 1, wherein each R is methyl and R1 is isopropyl.

5. The method according to claim 1, wherein X is iodine.

6. The method according to claim 1, wherein the method further comprises preparing the compound of formula (A) by reacting tin(II) chloride with a compound of formula MN(R)2, wherein M is a sodium ion, a lithium ion, or a potassium ion.

7. The method of claim 6, wherein the method is carried out in a reaction vessel.

8. A compound of formula (II), In this case, each R is the same or different and is a C1-C4 alkyl group, and X is iodine, bromine, or chlorine, provided that when X is chlorine, R is not methyl.

9. The compound according to claim 8, wherein each R is the same or different and is a C1-C4 alkyl group and X is iodine and bromine.

10. The compound according to claim 8, wherein each R is methyl and X is iodine.

11. The compound according to claim 10, which is in crystalline form and has the structure shown in FIG1.

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