Compounds and Methods for Extreme Ultraviolet Lithography

Abstract

The present disclosure includes the preparation of mixed ligand compounds such as tin(II) cyclopentadienylide complexes. The compounds of the present disclosure can be used as atomic layer deposition (ALD) precursors for extreme ultraviolet (EUV) lithography. The compounds of the present disclosure can also be used as plasma chemical vapor deposition (CVD) precursors for EUV lithography.

Description

Technical Field

[0001] This disclosure relates to the field of compounds and methods for extreme ultraviolet (EUV) lithography.

[0002] Priority Claim This disclosure claims priority to U.S. Provisional Patent Application No. 63 / 357,771, entitled "COMPOUNDS AND PROCESSES FOR EXTREME ULTRAVIOLET LITHOGRAPHY," filed on July 1, 2023, which is incorporated herein by reference.

Background Art

[0003] Extreme ultraviolet lithography is an optical lithography technique that uses the extreme ultraviolet wavelength range to generate patterns by exposing a reflective photomask to UV light and reflecting it onto a substrate covered with a photoresist.

Summary of the Invention

[0004] This disclosure includes the preparation of mixed ligand compounds such as tin(II) cyclopentadienylide complexes. The compounds of this disclosure can be used as precursors, for example, atomic layer deposition (ALD) precursors or plasma chemical vapor deposition (CVD) precursors for EUV lithography. For example, the compounds of this disclosure can be used for EUV hard mask applications. Tin compounds can also be used for other applications (e.g., polyvinyl chloride (PVC) stabilizers, biocides, precursors for tin(IV) oxide coatings, and catalysts for organic conversions).

[0005] In some embodiments, this disclosure TIFF2025520926000002.tif50170[In the above formula, each R 2 is independently hydrogen, C1-C4, or a halide containing C1-C4, TIFF2025520926000003.tif42170{In the above formula, R 3 ~R7 is hydrogen or C1-C4] comprises a cyclopentadienyltin(II) compound of formula (I) containing

[0006] In some embodiments, the present disclosure provides that each R 2 is independently a methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, t-butyl, or sec-butyl group.

[0007] In some embodiments, the present disclosure provides that each R 2 is a methyl group.

[0008] In some embodiments, the present disclosure provides that each R 2 is a C1-C4 alkyl group.

[0009] In some embodiments, the present disclosure provides that C1-C4 is branched or unbranched.

[0010] In some embodiments, the present disclosure provides that C1-C4 is substituted or unsubstituted.

[0011] In some embodiments, the present disclosure provides that each R 3 -R 7 is hydrogen.

[0012] In some embodiments, the present disclosure provides that each R 2 is hydrogen and each R 3 -R 7 is hydrogen.

[0013] In some embodiments, the present disclosure provides Formula (I): TIFF2025520926000004.tif50170[In the above formula, each R 2 is independently hydrogen, C1-C4, or a halide containing a C1-C4 group, TIFF2025520926000005.tif42170{In the above formula, R 3 ~R 7 is hydrogen or C1-C4]}] A method for forming a cyclopentadienyltin(II) compound of [Sn(N(R 2 ))2]2 with Cp2Sn or CpH, the method comprising:

[0014] In some embodiments, the disclosure includes [Sn(N(R 2 ))2]2 being dissolved in tetrahydrofuran prior to the contacting step.

[0015] In some embodiments, the disclosure includes R 2 being independently a methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, t-butyl, or sec-butyl group.

[0016] In some embodiments, the disclosure includes Cp2Sn or CpH being dissolved in tetrahydrofuran prior to the contacting step.

[0017] In some embodiments, the disclosure Formula (II): TIFF2025520926000006.tif55170[In the above formula, each R 1 is independently hydrogen, C1-C4, or a halide containing C1-C4, TIFF2025520926000007.tif42170{In the above formula, R 3 ~R 7 is hydrogen or C1-C4]}] including the cyclopentadienyltin(II) compound of

[0018] In some embodiments, the disclosure includes each R 1 being independently a methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, t-butyl, or sec-butyl group.

[0019] In some embodiments, the present disclosure includes each R 1 being a methyl group.

[0020] In some embodiments, the present disclosure includes each R 1 being a C1-C4 alkyl group.

[0021] In some embodiments, the present disclosure includes C1-C4 being branched or unbranched.

[0022] In some embodiments, the present disclosure includes C1-C4 being substituted or unsubstituted.

[0023] In some embodiments, the present disclosure includes each R 3 ~R 7 being hydrogen.

[0024] In some embodiments, the present disclosure includes each R 1 being hydrogen and each R 3 ~R 7 being hydrogen.

[0025] In some embodiments, the present disclosure is of formula (II): TIFF2025520926000008.tif56170[wherein each R 1 is independently hydrogen, C1-C4, or a halide containing a C1-C4 group, TIFF2025520926000009.tif41170{wherein R 3 ~R 7 are hydrogen or C1-C4}]] for forming a cyclopentadienylidene tin (II) compound, comprising [Sn(O(R 1 ))2]2 being contacted with Cp2Sn.

[0026] In some embodiments, the present disclosure includes that [[Sn(O(R 1 ))2]2 is dissolved in tetrahydrofuran before the contacting step.

[0027] In some embodiments, the present disclosure includes that R 1 is independently a methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, t-butyl, or sec-butyl group.

[0028] In some embodiments, the present disclosure includes that Cp2Sn is dissolved in tetrahydrofuran before the contacting step.

[0029] Some embodiments of the present disclosure are described herein by way of example only with reference to the accompanying drawings. Referring particularly to the drawings herein, it is emphasized that the embodiments shown are by way of example and are for illustrative explanation of embodiments of the present disclosure. In this regard, the description made with the use of the drawings makes it clear to those skilled in the art how embodiments of the present disclosure can be implemented.

Brief Description of the Drawings

[0030]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Among these disclosed advantages and improvements, other objects and advantages of the present disclosure will become apparent from the following description in conjunction with the accompanying drawings. Specific embodiments of the present disclosure are disclosed herein. However, it should be understood that the disclosed embodiments are merely illustrative examples of the present disclosure, which may be embodied in various forms. Furthermore, each of the examples given with respect to the various embodiments of the present disclosure is intended to be illustrative and not limiting.

[0032] All prior patents and publications referred to herein are hereby incorporated by reference in their entirety.

[0033] Throughout the specification and the claims, the following terms take the meanings explicitly associated with them herein, unless the context clearly indicates otherwise. As used herein, the phrases “in one embodiment,” “in an embodiment,” and “in some embodiments” do not necessarily refer to the same embodiment, but may. Further, the phrases “in another embodiment” and “in some other embodiments” as used herein do not necessarily refer to different embodiments, but may. All embodiments of the present disclosure are intended to be combinable without departing from the scope or spirit of the present disclosure.

[0034] As used herein, the term “based on” is not exclusive and allows for being based on additional factors not recited, unless the context clearly dictates otherwise. Further, throughout the specification, the meanings of “a,” “an,” and “the” include plural referents. The meaning of “in” includes “in” and “on.”

[0035] The present disclosure relates to compounds thereof, including the preparation of mixed ligand compounds. The mixed ligand compounds include tin(II) cyclopentadienylidene complexes containing cyclopentadienylidene amide and cyclopentadienylidene alkoxide. The compounds of the present disclosure can be used as atomic layer deposition (ALD) precursors for EUV lithography. For example, the compounds of the present disclosure can be used for EUV hard mask applications. The tin compounds can also be used for other applications (e.g., polyvinyl chloride (PVC) stabilizers, biocides, precursors for tin(IV) oxide coatings, and catalysts for organic conversions).

[0036] Figure 1 shows a non-limiting embodiment of a method 100 for synthesizing cyclopentadienylidene tin(II) amide described herein. In some embodiments, the present disclosure includes contacting [Sn(N(R 2 )2)2]2 with Cp2Sn 110 or CpH 120. In some embodiments, method 100 includes dissolving [Sn(N(R 2 )2)2]2 in tetrahydrofuran (THF) prior to the contacting step. In some embodiments, method 100 includes dissolving Cp2Sn or CpH in tetrahydrofuran (THF) prior to the contacting step.

[0037] In some embodiments, using Cp2Sn 110 in method 100 can include filling [Sn(N(R 2 )2)2]2 into a container (e.g., a vial) and dissolving it in tetrahydrofuran (THF). In another container, Cp2Sn can be added and dissolved in tetrahydrofuran (THF). Then, the solution having [Sn(N(R 2 )2)2]2 dissolved in THF can be added to the solution having Cp2Sn dissolved in THF. [Sn(N(R 2)2)2]2, The solution of Cp2Sn and tetrahydrofuran (THF) can be stirred for a certain period of time. The combined solution can be stirred for a long time, for example, 1 to 12 hours. For example, the combined solution can be stirred for more than 1 hour, more than 3 hours, more than 6 hours, more than 9 hours, less than 12 hours, less than 9 hours, less than 6 hours or less than 3 hours. After stirring the combined solution, the combined solution can then be dried. In some examples, the combined solution can be dried under reduced pressure to obtain a solid mass. The reduced pressure can be selected from the range of reduced pressure, for example, 100 millitorr to 760 torr (atm). For example, the reduced pressure can be more than 100 millitorr, more than 1 torr, more than 10 torr, more than 100 torr, more than 300 torr, more than 500 torr, more than 700 torr, less than 760 torr, less than 700 torr, less than 500 torr, less than 300 torr, less than 100 torr, less than 10 torr, or less than 1 torr. In some examples, the stirred solution can be dried under a dynamic vacuum including the reduced pressure values described herein. X-ray quality crystals can be grown by slowly evaporating a solution such as a concentrated benzene (C6D6) solution, a NMR solvent including tetrahydrofuran (THF), diethyl ether (Et2O), or toluene (PhMe).

[0038] In some embodiments, using CpH 120 in method 100 may include diluting cyclopentadiene with tetrahydrofuran (THF). Then, the solution of cyclopentadiene containing tetrahydrofuran (THF) can be added to the stirred solution of THF and [Sn(N(R 2 )2)2]2. [Sn(N(R 2)2)2]2. A solution combined with CpH and tetrahydrofuran (THF) can be stirred for a certain period of time. The combined solution can be stirred for a long time, for example, 1 to 12 hours. For example, the combined solution can be stirred for more than 1 hour, more than 3 hours, more than 6 hours, more than 9 hours, less than 12 hours, less than 9 hours, less than 6 hours, or less than 3 hours. After stirring the combined solution, the combined solution can then be dried. In some examples, the stirred solution can be dried under reduced pressure to obtain a solid mass. For example, the reduced pressure can be more than 100 millitorr, more than 1 torr, more than 10 torr, more than 100 torr, more than 300 torr, more than 500 torr, more than 700 torr, less than 760 torr, less than 700 torr, less than 500 torr, less than 300 torr, less than 100 torr, less than 10 torr, or less than 1 torr. In some examples, the stirred solution can be dried under a dynamic vacuum including the reduced pressure values described herein.

[0039] In some embodiments, using Cp2Sn 110 or CpH 120 in the method 100 of the present disclosure results in a cyclopentadienylidene tin (II) compound of formula (I): TIFF2025520926000010.tif49170.

[0040] In some embodiments, each R 2 is independently hydrogen or C1 - C4.

[0041] In some embodiments, each R 2 is independently a methyl, ethyl, propyl, isopropyl, n - butyl, isobutyl, t - butyl, or sec - butyl group. In some embodiments, each R 2 is a methyl group. In some embodiments, each R 2 is a C1 - C4 alkyl group.

[0042] In some embodiments, cyclopentadienylidene (Cp) has the formula (1): TIFF2025520926000011.tif43170.

[0043] In some embodiments, R 3 ~R 7 is hydrogen or C1-C4. In some embodiments, each R 3 ~R 7 is independently a methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, t-butyl, or sec-butyl group. In some embodiments, each R 2 is a methyl group.

[0044] In some embodiments, C1-C4 is branched or unbranched. In some embodiments, C1-C4 is substituted or unsubstituted.

[0045] In some embodiments, each R 2 is a methyl group and each R 3 ~R 7 is hydrogen. In some embodiments, each R 2 is hydrogen and each R 3 ~R 7 is hydrogen.

[0046] In some embodiments, the present disclosure includes forming a cyclopentadienylidene tin (II) compound of formula (I). In some embodiments, each R 2 is independently hydrogen, C1-C4, or a halide containing a C1-C4 group.

[0047] In some embodiments, cyclopentadienylidene (Cp) has formula (1). In some embodiments, R 3 ~R 7 is hydrogen or C1-C4. In some embodiments, method 100 includes forming a cyclopentadienylidene tin (II) compound of formula (I) by contacting [Sn(N(R 2 )2)2]2 with Cp2Sn or CpH. In some embodiments, method 100 includes, prior to the contacting step, [Sn(N(R 2)2)2]2 is dissolved in tetrahydrofuran (THF). In some embodiments, method 100 includes dissolving Cp2Sn or CpH in tetrahydrofuran (THF) prior to the contacting step.

[0048] Figure 2 shows a non-limiting embodiment of a method 200 for synthesizing cyclopentadienylidene tin (II) alkoxide described herein. In some embodiments, the present disclosure includes contacting [[Sn(O(R 1 ))2]2 with Cp2Sn. In some embodiments, method 200 includes dissolving [[Sn(O(R 1 ))2]2 in tetrahydrofuran (THF) prior to the contacting step. In some embodiments, method 200 includes dissolving Cp2Sn in tetrahydrofuran (THF) prior to the contacting step.

[0049] In some embodiments, using Cp2Sn in method 200 of the present disclosure involves the formula (II): TIFF2025520926000012.tif55170 includes cyclopentadienylidene tin (II) compounds.

[0050] In some embodiments, each R 1 is independently hydrogen, C1-C4, or a halide containing C1-C4.

[0051] In some embodiments, each R 1 is independently a methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, t-butyl, or sec-butyl group. In some embodiments, each R 1 is a methyl group. In some embodiments, each R 1 is a C1-C4 alkyl group. In some embodiments, each R 1 is a C1-C4 alkyl group containing at least one halide (e.g., fluorine (F), chlorine (Cl), bromine (Br), or iodine (I)). For example, R 1can be -OCH2CF3 (trifluoroethoxide).

[0052] In some embodiments, the cyclopentadienylide (Cp) has the formula (1): TIFF2025520926000013.tif41170.

[0053] In some embodiments, R 3 ~R 7 is hydrogen or C1-C4. In some embodiments, each R 3 ~R 7 is independently a methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, t-butyl, or sec-butyl group. In some embodiments, each R 1 is a methyl group.

[0054] In some embodiments, C1-C4 is branched or unbranched. In some embodiments, C1-C4 is substituted or unsubstituted.

[0055] In some embodiments, each R 1 is a methyl group and each R 3 ~R 7 is hydrogen. In some embodiments, each R 1 is hydrogen and each R 3 ~R 7 is hydrogen.

[0056] In some embodiments, the present disclosure includes forming a cyclopentadienylide tin (II) compound of formula (II). In some embodiments, each R 1 is independently hydrogen, C1-C4, or a halide containing a C1-C4 group.

[0057] In some embodiments, the cyclopentadienylide (Cp) has the formula (1). In some embodiments, R 3 ~R 7is hydrogen or C1 - C4. In some embodiments, method 200 includes 1 forming a cyclopentadienylidene tin(II) compound of formula (II) by contacting [[Sn(O(R 1 ))2]2 with Cp2Sn. In some embodiments, method 200 includes dissolving [[Sn(O(R

Examples

[0058] Example 1

[0059] Figure 3 shows a non - limiting example of a method 300 for synthesizing cyclopentadienyl tin(II) amide using Cp2Sn described herein.

[0060] [Sn(N(CH3)2)2]2 (1.0 g, 3.98 mmol) was placed in an amber 40 mL vial and dissolved in tetrahydrofuran (10 mL). Cp2Sn was placed in another amber 40 mL vial equipped with a magnetic stir bar and dissolved in THF (10 mL). The [Sn(N(CH3)2)2]2 solution was added to the Cp2Sn solution with stirring over 5 minutes. The resulting pale yellow solution was stirred at room temperature overnight. The next day, the pale yellow solution was dried under reduced pressure to obtain [CpSn(N(CH3)2)]2 as an off - white / yellow solid (mass: 1.63 g, yield: 89.5%). X - ray quality crystals were grown by slowly evaporating a concentrated C6D6 solution. 1 H - NMR (400 MHz, d8 - THF, 298K): 2.65 (s, 6H); 2.73 (s, 6H); 6.12 (s, 10H) ppm; 13 C{ 1 H}-NMR (100 MHz, d8 - THF, 298K): 44.06 ppm; 119 Sn{ 1 H}-NMR (149 MHz, d8 - THF, 298K): - 287.3, - 306.12 ppm.

[0061] Figure 4 shows the solid structure of [CpSn(N(CH3)2)]2 determined by X-ray crystallography.

[0062] TIFF2025520926000014.tif175170

[0063] Example 2

[0064] Figure 5 shows a non-limiting example of method 600 for synthesizing cyclopentadienyltin(II) amide using CpH described herein.

[0065] Cyclopentadiene (0.158 g, 2.40 mmol) was diluted with 3 mL of tetrahydrofuran and added dropwise over 5 minutes to a stirred solution of 3 mL of THF of [Sn(N(CH3)2)2]2 (0.500 g, 1.20 mmol), and the resulting pale yellow solution was stirred overnight. The next day, the volatile substances were removed under reduced pressure to obtain [CpSn(N(CH3)2)]2 as a pale yellow solid. Collected in a d8-THF solution of the product 1 H-, 13 C- and 119 - Sn-NMR is consistent with a combination of Cp2Sn and [Sn(N(CH3)2)2]2.

[0066] Aspect

[0067] The following various aspects will be described. It should be understood that any one or more of the features described in the following aspects can be combined with any one or more of the other aspects.

[0068] Aspect 1. TIFF2025520926000015.tif49170[In the above formula, each R 2 is independently hydrogen, C1-C4, or a halide containing C1-C4, TIFF2025520926000016.tif40170{In the above formula, R 3 ~R 7is hydrogen or C1 - C4] A cyclopentadienyltin(II) compound of formula (I) containing

[0069] Embodiment 2. Each R 2 is independently a methyl, ethyl, propyl, isopropyl, n - butyl, isobutyl, t - butyl, or sec - butyl group, the compound according to Embodiment 1.

[0070] Embodiment 3: Each R 2 is a methyl group, the compound according to Embodiment 1.

[0071] Embodiment 4: Each R 2 is a C1 - C4 alkyl group, the compound according to Embodiment 1.

[0072] Embodiment 5: C1 - C4 is branched or unbranched, the compound according to any one of Embodiments 1 to 4.

[0073] Embodiment 6. C1 - C4 is substituted or unsubstituted, the compound according to any one of Embodiments 1 to 5.

[0074] Embodiment 7: Each R 3 ~R 7 is hydrogen, the compound according to any one of Embodiments 1 to 6.

[0075] Embodiment 8: Each R 2 is hydrogen, and each R 3 ~R 7 is hydrogen, the compound according to Embodiment 1.

[0076] Embodiment 9. Formula (I): TIFF2025520926000017.tif49170[In the above formula, each R 2 is independently hydrogen, C1 - C4, or a halide containing a C1 - C4 group, TIFF2025520926000018.tif41170{In the above formula, R 3 ~R 7 is hydrogen or C1 - C4] A method for forming a cyclopentadienyltin(II) compound, comprising: [Sn(N(R 2 ))2]2 is contacted with Cp2Sn or CpH, Method.

[0077] Aspect 10: The method according to aspect 9, wherein [Sn(N(R 2 ))2]2 is dissolved in tetrahydrofuran before the contacting step.

[0078] Aspect 11. R 2 is independently a methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, t-butyl, or sec-butyl group, the method according to aspect 9 or aspect 10.

[0079] Aspect 12: The method according to any one of aspects 9 to 11, wherein Cp2Sn or CpH is dissolved in tetrahydrofuran before the contacting step.

[0080] Aspect 13. Formula (II): TIFF2025520926000019.tif55170[In the above formula, each R 1 is independently hydrogen, C1-C4, or a halide containing C1-C4, TIFF2025520926000020.tif41170{In the above formula, R 3 ~R 7 are hydrogen or C1-C4}] Cyclopentadienyltin(II) compound.

[0081] Aspect 14. Each R 1 is independently a methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, t-butyl, or sec-butyl group, the compound according to aspect 13.

[0082] Aspect 15: The compound according to aspect 13, wherein each R 1 is a methyl group.

[0083] Aspect 16: Each R 1The compound according to embodiment 13, wherein it is a C1-C4 alkyl group.

[0084] Embodiment 17: The compound according to any one of embodiments 13 to 16, wherein C1-C4 is branched or unbranched.

[0085] Embodiment 18: The compound according to any one of embodiments 13 to 17, wherein C1-C4 is substituted or unsubstituted.

[0086] Embodiment 19: Each R 3 ~R 7 is hydrogen, and the compound according to any one of embodiments 13 to 18.

[0087] Embodiment 20: Each R 1 is hydrogen, each R 3 ~R 7 is hydrogen, and the compound according to embodiment 13.

[0088] Embodiment 21. Formula (II): TIFF2025520926000021.tif54170[In the above formula, each R 1 is, independently, hydrogen, C1-C4, or a halide containing a C1-C4 group, TIFF2025520926000022.tif40170{In the above formula, R 3 ~R 7 is hydrogen or C1-C4}] is a method for forming a cyclopentadienyltin(II) compound of [Sn(O(R 1 ))2]2 with Cp2Sn, Method.

[0089] Embodiment 22: The method according to embodiment 21, wherein [Sn(O(R 1 ))2]2 is dissolved in tetrahydrofuran before the contacting step.

[0090] Embodiment 23. R 1The method according to embodiment 21 or embodiment 22, wherein each is independently a methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, t-butyl, or sec-butyl group.

[0091] Embodiment 24: The method according to any one of embodiments 21 to 23, wherein Cp2Sn is dissolved in tetrahydrofuran before the contacting step.

[0092] It should be understood that changes may be made in detail, particularly with regard to the constituent materials used and the shape, size, and arrangement of the parts, without departing from the scope of the present disclosure. The present specification and the described embodiments are examples, and the true scope and spirit of the present disclosure are indicated by the appended claims.

Claims

【Claim 1】 [wherein each R ２ is independently hydrogen, C １ to C ４ or a halide containing C １ to C ４ and is a halide containing C {In the above formula, R ３ to R ７ is hydrogen or C １ to C ４} A cyclopentadienyltin(II) compound of formula (I) containing Claim 2 Each R ２ The compound according to claim 1, wherein each R is independently a methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, t-butyl, or sec-butyl group. Claim 3 Each R ２ The compound according to claim 1, wherein R is a methyl group. Claim 4 Each R ２ is C １ to C ４ an alkyl group, the compound according to claim 1. Claim 5 C １ -C ４ The compound according to claim 1, wherein C to C is branched or unbranched. Claim 6 C １ -C ４ The compound according to claim 1, wherein C Claim 7 Each R ３ ~R ７ The compound according to claim 1, wherein each R is hydrogen. Claim 8 Each R ２ is hydrogen, and each R ３ to R ７ is hydrogen, the compound according to claim 1. Claim 9 Formula (I): [In the above formula, each R ２ is independently hydrogen, C １ to C ４ or a halide containing a C １ to C ４ group, and {In the above formula, R ３ to R ７ is hydrogen or C １ to C ４} A method for forming a cyclopentadienyltin(II) compound of [Sn(N(R ２ )) ２ ) ２ ２ is contacted with Cp ２ Sn or CpH, comprising Method Claim 10 Before the contacting step, dissolve ２ ) ２ ) ２ ２ in tetrahydrofuran, the method according to claim 9. Claim 11 R ２ The method according to claim 10, wherein R is independently a methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, t-butyl, or sec-butyl group. Claim 12 Cp before the contacting step ２ The method according to claim 9, wherein Sn or CpH is dissolved in tetrahydrofuran. Claim 13 Formula (II): [In the above formula, each R １ is, independently, hydrogen, C １ to C ４ , or a halide containing C １ to C ４ and is a halide containing {In the above formula, R ３ to R ７ is hydrogen or C １ to C ４} A cyclopentadienyltin(II) compound of Claim 14 Each R １ The compound according to claim 13, wherein each R is independently a methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, t-butyl, or sec-butyl group. Claim 15 Each R １ The compound according to claim 13, wherein R is a methyl group. Claim 16 Each R １ is C １ -C ４ an alkyl group, the compound according to claim 13. Claim 17 C １ -C ４ The compound according to claim 13, wherein C to C is branched or unbranched. Claim 18 C １ ~C ４ The compound according to claim 13, wherein C １ ~C ４ is substituted or unsubstituted. Claim 19 Each R ３ to R ７ is hydrogen, the compound according to claim 13. Claim 20 Each R １ is hydrogen, and each R ３ to R ７ is hydrogen, the compound according to claim 13. Claim 21 Formula (II): [In the above formula, each R １ is, independently, hydrogen, C １ to C ４ , or a halide containing a C １ to C ４ group, and {In the above formula, R ３ to R ７ is hydrogen or C １ to C ４} A method for forming a cyclopentadienyltin(II) compound of [Sn(O(R １ )) ２ ２ is contacted with Cp ２ Sn, comprising​ Method Claim 22 Before the contacting step, [Sn(O(R １ )) ２ ２ is dissolved in tetrahydrofuran, the method according to claim 21. Claim 23 R １ The method according to claim 22, wherein R is independently a methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, t-butyl, or sec-butyl group. Claim 24 Before the contacting step, Cp ２ The method according to claim 21, wherein Sn is dissolved in tetrahydrofuran.

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