Precursor alpha-diimino dimethyl Fe (III) compound for Fe-based thin film material

Abstract

The invention discloses a precursor alpha-diimino dimethyl Fe (III) compound for a Fe-based thin film material, and belongs to the technical field of microelectronic materials. The invention provides an alpha-diimino dimethyl Fe (III) compound as shown in a formula (I), the compound has good volatility, thermal stability, oxygen-resistant stability and good film-forming property, can be used as a precursor of chemical vapor deposition (CVD) / atomic layer deposition (ALD), and can be used for preparing a good Fe-based film through a CVD / ALD process. Meanwhile, the synthesis method is simple and convenient, the conditions are mild, the used raw materials are cheap and easy to obtain, and the synthesis cost of the precursor material is greatly reduced. # imgabs0 #

Description

Technical Field

[0001] The present invention relates to a precursor α-diimino dimethyl Fe(III) compound for Fe-based thin film materials, belonging to the technical field of microelectronic materials. Background Art

[0002] With the development of the Internet, Internet of Things, and big data, information storage technology is constantly facing new requirements and challenges. The core of the development of information storage technology lies in information storage materials, and major countries and companies around the world have invested huge R & D efforts in this regard. Magnetic metal iron and its alloy nanofilms have been widely studied in recent years as information storage materials. For example, in addition to Fe metal nanofilm materials being able to be used as the basic materials for preparing magnetic random access memories, some of its alloys such as cobalt iron boron, iron oxide, etc. are considered strong competitors for next-generation microelectronic materials for information storage due to their excellent properties.

[0003] The performance of thin film materials is closely related to the material preparation technology selected. The traditional preparation methods of Fe-based thin film materials mainly include magnetron sputtering, molecular beam epitaxy, pulsed laser deposition, etc. However, with the continuous reduction of the feature size of microelectronic devices and the continuous increase of the aspect ratio of device structures, it has become extremely difficult to fill the materials, and traditional deposition methods can no longer meet the requirements. Chemical vapor deposition (CVD) and atomic layer deposition (ALD) technologies have become new device manufacturing technologies due to their advantages such as good conformal coating and good uniformity. In the CVD / ALD process technology, the properties of the precursor are crucial. It is required that the precursor has excellent volatility, thermal stability, and reactivity. In addition, it also needs to have high purity, be easy to store, be non-toxic, be easy to synthesize, be inexpensive, and have as high a water and oxygen resistance stability as possible, so as to facilitate operation, use, storage, and transportation. Therefore, whether there is a suitable precursor affects the success or failure of the entire CVD / ALD process.

[0004] Currently reported iron precursors that can be used in CVD / ALD technology to prepare metallic iron and related thin films still have one or several of the following problems respectively: too low volatility; easy to spontaneously combust and highly toxic, which increases the risk of its use; too low thermal stability, easy to decompose / volatilize, and cannot be stored for a long time; the prepared thin films are prone to have a relatively high carbon content, etc. At the same time, different precursors will directly affect the composition and performance of the finally prepared thin film materials due to reasons such as their own structures and process parameters. Moreover, the types and quantities of currently developed Fe precursors are relatively small and are not sufficient to meet the huge demands generated by people for the preparation of different types and performance materials. Therefore, in the context of the continuous replacement of related technologies, it has become very urgent to explore and synthesize more types of CVD / ALD Fe precursors to meet the increasing demands. Summary of the Invention

[0005] To solve at least one of the above problems, the object of the present invention is to provide a novel iron precursor α-diimino dimethyl Fe(III) compound for Fe-based thin film materials, which has a simple synthesis method, mild synthesis conditions, good solubility in organic solvents such as n-hexane, toluene, tetrahydrofuran, dichloromethane, etc., good volatility, thermal stability and oxygen resistance stability, and good film-forming performance.

[0006] The first object of the present invention is to provide an α-diimino dimethyl Fe(III) compound having the structure shown in the general formula (I):

[0007]

[0008] Wherein, R is a hydrogen atom, a C1-C6 alkyl group, a C2-C5 alkenyl group, a C2-C5 cycloalkyl group, a C6-C 10 aryl group or -Si(R 1 )3, and R 1 is a C1-C6 alkyl group.

[0009] In an embodiment of the present invention, R is further optionally a C1-C4 alkyl group, a phenyl group, -Si(R 1 )3, and R 1 is a C1-C4 alkyl group.

[0010] In an embodiment of the present invention, the structure of the α-diimino dimethyl Fe(III) compound specifically includes:

[0011]

[0012] The second object of the present invention is to provide a method for preparing the above-mentioned α-diimino dimethyl Fe(III) compound, and the method specifically includes the following steps:

[0013]

[0014] (1) Dissolve the α-diimine compound having the structure shown in formula (II) in tetrahydrofuran, add metallic lithium under the condition of stirring at -78 °C, and then continue to stir and react for 24 to 48 h after restoring to room temperature to obtain a reaction mixture;

[0015] (2) Dissolve ferric chloride in tetrahydrofuran to obtain a ferric chloride tetrahydrofuran solution;

[0016] (3) Slowly add the reaction mixture obtained in step (1) to the ferric chloride tetrahydrofuran solution obtained in step (2) at -78 °C, slowly warm up to room temperature, and the heating rate is 0.5 to 1 °C / min, and continue to stir and react at room temperature for 10 to 24 hours;

[0017] (4) Under the condition of maintaining stirring at -78 °C, add methyllithium to the reaction solution obtained after the reaction in step (3), slowly warm up to room temperature at a heating rate of 0.5 - 1 °C / min, and continue stirring and reacting at room temperature for 24 hours;

[0018] (5) After the reaction in step (4) is completed, remove volatile substances under reduced pressure, then add hexane or toluene solution to dissolve, filter and extract, collect the filtrate, and obtain the α-diimino dimethyl Fe(III) compound after repeated recrystallization at -30 °C.

[0019] In one embodiment of the present invention, the molar ratio of the α-diimine compound to metallic lithium in step (1) is 1:1.0 - 1.3. Further, it is 1:1 - 1:1.2.

[0020] In one embodiment of the present invention, the mass ratio of the α-diimine compound to tetrahydrofuran in step (1) is 1:10 - 1:20.

[0021] In one embodiment of the present invention, the mass ratio of the α-diimine compound to tetrahydrofuran in step (1) is 1:10 - 1:20.

[0022] In one embodiment of the present invention, the molar ratio of the α-diimine compound in step (1) to ferric chloride in step (2) is 1:0.9 - 1.1. Specifically, 1:1 can be selected.

[0023] In one embodiment of the present invention, the mass ratio of ferric chloride to tetrahydrofuran in step (2) is 1:10 - 1:20.

[0024] In one embodiment of the present invention, the molar ratio of methyllithium in step (4) to ferric chloride in step (2) is 2:(0.9 - 1.1). Specifically, 2:1 can be selected.

[0025] In one embodiment of the present invention, the stirring speed in step (1) is 100 - 1000 revolutions / min.

[0026] The third object of the present invention is to provide the application of the above α-diimino dimethyl Fe(III) compound in the field of preparation of microelectronic materials.

[0027] The fourth object of the present invention is to provide the application of the above α-diimino dimethyl Fe(III) compound in the field of preparation of information storage materials.

[0028] The fifth object of the present invention is to provide the application of the above α-diimino dimethyl Fe(III) compound in the field of preparation of Fe-based thin film materials.

[0029] In one embodiment of the present invention, the application is to use the above-mentioned α-diimino dimethyl Fe(III) compound as a precursor to prepare a metal or metal alloy film through a chemical vapor deposition process or an atomic layer deposition process.

[0030] Advantages of the present invention:

[0031] The α-diimino dimethyl Fe(III) compound obtained in the present invention can be used as a precursor for CVD / ALD. Through a chemical vapor deposition (CVD) or atomic layer deposition (ALD) process, an Fe-based film such as FeO X film can be prepared. The α-diimino dimethyl Fe(III) compound described in the present invention has the following advantages: (1) The raw material ferric chloride used is cheaper and more easily available than ferrous chloride, greatly reducing the synthesis cost of the precursor material; (2) It has good solubility in organic solvents such as n-hexane, toluene, tetrahydrofuran, and dichloromethane, making the precursor transportation, delivery, and processing processes simple and easy to operate; (3) It has good volatility and thermal stability. For example, through thermogravimetric (TG) testing of the thermal properties of the precursor, the T 50 of the tert-butyl-α-diimino dimethyl Fe(III) precursor under normal pressure is 222.77 °C, and the minimum residual mass is 4.75%; (4) The complex is a trivalent iron complex, with good oxygen stability at room temperature, facilitating operation and use; (5) It has good film-forming performance. Taking the tert-butyl-α-diimino dimethyl Fe(III) precursor as an example, with N2 as the carrier gas and O2 as the reaction gas, at 350 °C, a good CVD FeO X film can be formed. Description of the drawings

[0032] Figure 1 is the single crystal structure diagram of the tert-butyl-α-diimino dimethyl Fe(III) precursor;

[0033] Figure 2 is the TG spectrum of the tert-butyl-α-diimino dimethyl Fe(III) precursor. The abscissa is temperature in °C, and the ordinate is the weight loss rate (%);

[0034] Figure 3 is the SEM image of the CVD thin film material obtained using the tert-butyl-α-diimino dimethyl Fe(III) precursor;

[0035] Figure 4 is the XPS image of the CVD thin film material obtained using the tert-butyl-α-diimino dimethyl Fe(III) precursor. Specific embodiments

[0036] To better understand the technical content of the present invention, the following examples are provided for detailed illustration. Their purpose is only to better understand the content of the present invention rather than to limit the protection scope of the present invention.

[0037] The preparation method of the α-diimino dimethyl Fe(III) precursor described in the present invention is carried out according to the following reaction route:

[0038]

[0039] Example 1

[0040] A preparation method of the α-diimino dimethyl Fe(III) compound as a precursor for Fe-based thin film materials includes the following steps:

[0041] (1) Dissolve the tert-butyl α-diimine compound in tetrahydrofuran. The mass ratio of tert-butyl α-diimine to the tetrahydrofuran solvent is 1:20. While maintaining stirring at -78°C, add metallic lithium in a molar ratio of tert-butyl α-diimine to lithium of 1:1. The stirring speed is 800 revolutions per minute. After restoring to room temperature, continue stirring and reacting for 24 hours to obtain a reaction mixture;

[0042] (2) Another, weigh a certain amount of ferric chloride according to the molar ratio of tert-butyl α-diimine to ferric chloride of 1:1, and dissolve it in tetrahydrofuran to obtain a ferric chloride tetrahydrofuran solution; wherein, the mass ratio of ferric chloride to tetrahydrofuran is 1:20;

[0043] (3) At -78°C, add the reaction mixture obtained in step (1) to the ferric chloride tetrahydrofuran solution obtained in step (2) at one time, slowly warm up to room temperature at a heating rate of 1°C / min, and continue stirring and reacting at room temperature for 15 hours;

[0044] (4) Another, weigh a certain amount of methyllithium according to the molar ratio of methyllithium to ferric chloride of 2:1, and add it to the reaction solution obtained in step (3) while maintaining stirring at -78°C, slowly warm up to room temperature at a heating rate of 1°C / min, and continue stirring and reacting at room temperature for 24 hours;

[0045] (5) After the reaction in step (4) is completed, remove volatile substances under reduced pressure, then add hexane or toluene solution to dissolve, filter and extract, collect the filtrate, and obtain the target product (tert-butyl α-diimino dimethyl iron) after repeated recrystallization at -30°C.

[0046] The structural formula of the target product (tert-butyl α-diimino dimethyl iron) is: Yield: 76%, elemental analysis: C, 56.35; H, 10.20; N, 11.17; the theoretically elemental analysis values are C, 56.70; H, 10.31; N, 11.02. The structure of the target product was analyzed by single crystal X-ray diffraction, and the specific structure is as Figure 1 shown.

[0047] The synthesized target product, tert-butyl α-diimino dimethyl iron precursor, has good solubility in organic solvents such as n-hexane, toluene, tetrahydrofuran, and dichloromethane, making the transportation, delivery, and processing of the precursor simple and easy to operate.

[0048] The thermal properties of the precursor were tested by thermogravimetry (TG). Under atmospheric pressure, the T 50 of the tert-butyl α-diimino dimethyl iron precursor is 222.77 °C, and the minimum residual mass is 4.75%. The results are shown in Figure 2 , indicating good volatility and thermal stability.

[0049] CVD deposition of thin films:

[0050] Using the obtained target product (tert-butyl α-diimino dimethyl iron) as the precursor, the growth parameters used in the CVD deposition process are: total pressure 15 torr, N2 flow rate: 120 mL / min, O2: 100 mL / min, deposition time: 30 min, deposition temperature: 350 °C, film formation rate: 7.7 nm / min. The SEM and XPS diagrams of the obtained deposited thin films are shown in Figure 3 and Figure 4 .

[0051] Example 2

[0052] A preparation method of a precursor α-diimino dimethyl Fe(III) compound for Fe-based thin film materials, comprising the following steps:

[0053] (1) Dissolve phenyl α-diimine in tetrahydrofuran, with the mass ratio of phenyl α-diimine to tetrahydrofuran solvent being 1:25. Under the condition of stirring at -78 °C, add metallic lithium in a molar ratio of phenyl α-diimine to lithium of 1:1.2, and the stirring speed is 800 revolutions / min; after restoring to room temperature, continue stirring and reacting for 48 h to obtain a reaction mixture;

[0054] (2) Separately, according to the molar ratio of phenyl α-diimine to ferric chloride of 1:1, weigh a certain amount of ferric chloride and dissolve it in tetrahydrofuran to obtain a ferric chloride tetrahydrofuran solution; wherein, the mass ratio of ferric chloride to tetrahydrofuran is 1:25;

[0055] (3) adding the reaction mixture obtained in step (1) to the ferric chloride tetrahydrofuran solution obtained in step (2) at -78°C, slowly heating to room temperature at a heating rate of 1°C / min, and continuing to stir and react at room temperature for 15 hours;

[0056] (4) Weigh a certain amount of methyl lithium in a molar ratio of methyl lithium to ferric chloride of 2:1, add it to the reaction solution obtained in step (3) under stirring at -78°C, slowly heat it to room temperature at a heating rate of 1°C / min, and continue stirring and reacting at room temperature for 24 hours;

[0057] (5) After the reaction in step (4) is completed, the volatile matter is removed by decompression, and then hexane or toluene solution is added for dissolution, filtered and extracted, the filtrate is collected, and the target product (phenyl α-diimino dimethyl iron) is obtained after repeated recrystallization at -30°C.

[0058] The structural formula of the target product (phenyl α-diimino dimethyl iron) is: Yield: 69%, elemental analysis: C, 65.15; H, 6.08; N, 9.61; theoretical elemental analysis values are C, 65.33; H, 6.17; N, 9.47.

[0059] The synthesized target product, phenyl α-diimino dimethyl iron precursor, has good solubility in organic solvents such as n-hexane, toluene, tetrahydrofuran, and dichloromethane, making the transportation, delivery, and processing of the precursor simple and easy to operate.

[0060] The thermal properties of the precursor were tested by thermogravimetric (TG) method. The T 50 The temperature is 252.11℃, the minimum residual mass is 7.13%, and it has good volatility and thermal stability.

[0061] CVD deposited thin films:

[0062] The obtained target product (phenyl α-diimino dimethyl iron) was used as a precursor, and the growth parameters used in the CVD deposition process were: total pressure 15 torr, N2 flow rate: 120 mL / min, O2: 100 mL / min, deposition time: 30 min, deposition temperature: 350°C, and film formation rate: 4.6 nm / min.

[0063] Example 3

[0064] A method for preparing an α-diiminodimethyl Fe(III) compound as a precursor for an Fe-based thin film material comprises the following steps:

[0065] (1) Dissolve trimethylsilyl α - diimine in tetrahydrofuran. The mass ratio of trimethylsilyl α - diimine to the tetrahydrofuran solvent is 1:15. Under the condition of stirring at - 78 °C, add metallic lithium according to the molar ratio of trimethylsilyl α - diimine to lithium of 1:1.1, and the stirring speed is 600 revolutions / min; After restoring to room temperature, continue stirring and reacting for 30 h to obtain a reaction mixture;

[0066] (2) Separately, according to the molar ratio of trimethylsilyl α - diimine to iron(III) chloride of 1:1, weigh a certain amount of iron(III) chloride and dissolve it in tetrahydrofuran to obtain an iron(III) chloride tetrahydrofuran solution; Among them, the mass ratio of iron(III) chloride to tetrahydrofuran is 1:15;

[0067] (3) At - 78 °C, add the reaction mixture obtained in step (1) to the iron(III) chloride tetrahydrofuran solution obtained in step (2) at one time, slowly warm up to room temperature, and the heating rate is 0.5 °C / min. Continue stirring and reacting at room temperature for 20 hours;

[0068] (4) Separately, according to the molar ratio of methyllithium to iron(III) chloride of 2:1, weigh a certain amount of methyllithium, and add it to the reaction solution obtained in step (3) under the condition of stirring at - 78 °C, slowly warm up to room temperature, and the heating rate is 1 °C / min. Continue stirring and reacting at room temperature for 24 hours;

[0069] (5) After the reaction in step (4) is completed, remove volatile substances under reduced pressure, then add hexane or toluene solution to dissolve, filter and extract, collect the filtrate, and obtain the target product (trimethylsilyl α - diiminodimethyliron) after repeated recrystallization at - 30 °C.

[0070] The structural formula of the target product (trimethylsilyl α - diiminodimethyliron) is: Yield: 59%, elemental analysis: C, 41.69; H, 9.23; N, 9.81; The theoretically elemental analysis values are C, 41.95; H, 9.15; N, 9.78.

[0071] The synthesized target product, trimethylsilyl α - diiminodimethyliron precursor, has good solubility in organic solvents such as n - hexane, toluene, tetrahydrofuran, and dichloromethane, making the transportation, conveyance, and processing processes of the precursor simple and easy to operate.

[0072] The thermal properties of the precursor were tested by thermogravimetry (TG). Under normal pressure, the T 50 of the trimethylsilyl α - diiminodimethyliron precursor is 235.66 °C, and the minimum residual mass is 5.57%, showing good volatility and thermal stability.

[0073] CVD deposition film:

[0074] Using the obtained target product (trimethylsilyl α-diimino dimethyl iron) as a precursor, the growth parameters used in the CVD deposition process are: total pressure 15 torr, N2 flow rate: 120 mL / min, O2: 100 mL / min, deposition time: 30 min, deposition temperature: 350 °C, and film formation rate: 5.3 nm / min.

[0075] Comparative Example 1

[0076] Using an O-containing ligand Fe complex - ferrous acetylacetonate as a precursor for CVD / ALD thin film deposition, and comparing its properties with the precursor in Example 1. The structure of the ferrous acetylacetonate complex is as follows:

[0077]

[0078] This precursor has poor thermal volatility and thermal stability, and is prone to decomposition during storage, which increases the difficulty of operation, transportation, delivery, and processing of the precursor. In addition, the thin film prepared from this precursor is prone to have a high impurity content, which is not conducive to industrial application.

[0079] Comparative Example 2

[0080] Using ferrocene complex as a precursor for CVD / ALD thin film deposition, and comparing its properties with the precursor in Example 1. The structure of the ferrocene complex is as follows:

[0081]

[0082] Although this precursor has high volatility and thermal stability, the thin film prepared from this precursor is prone to have a high impurity content, which is not conducive to industrial application.

[0083] Comparative Example 3

[0084] Using α-diimino dicarbonyl iron compound as a precursor for CVD / ALD thin film deposition, and comparing its properties with the precursor in Example 1. The structure of the α-diimino dicarbonyl iron compound is as follows:

[0085]

[0086] This complex has poor thermal stability and is not easy to store. Moreover, carbonyl complexes generally have high toxicity and pyrophoricity, which increases the difficulty of operation, transportation, delivery, and processing of the precursor, and is not conducive to industrial application.

[0087] Although the present invention has been disclosed above in its preferred embodiments, it is not intended to limit the present invention. Anyone skilled in this technology can make various modifications and alterations without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention should be defined by the claims.

Claims

1. An α-diimino dimethyl Fe(III) compound having the structure shown in general formula (I): Among them, R is a hydrogen atom, a C1-C6 alkyl group, a C2-C5 alkenyl group, a C2-C5 cycloalkyl group, a C6-C 10 aryl group or -Si(R 1 )3; R 1 is a C1-C6 alkyl group.

2. The α-diimino dimethyl Fe(III) compound according to claim 1, characterized in that, Its structure includes:

3. The preparation method of the α-diimino dimethyl Fe(III) compound according to claim 1, characterized in that, The method includes the following steps: (1) Dissolve the α-diimine compound shown in formula (II) in tetrahydrofuran, add metallic lithium while maintaining stirring at -78 °C, then restore to room temperature and continue stirring and reacting for 24 - 48 h to obtain a reaction mixture; (2) Dissolve ferric chloride in tetrahydrofuran to obtain a ferric chloride tetrahydrofuran solution; (3) Slowly add the reaction mixture obtained in step (1) to the ferric chloride tetrahydrofuran solution obtained in step (2) at -78 °C, slowly warm up to room temperature at a rate of 0.5 - 1 °C / min, and continue stirring and reacting at room temperature for 10 - 24 hours; (4) Add methyllithium to the reaction solution after the reaction in step (3) while maintaining stirring at -78 °C, slowly warm up to room temperature at a rate of 0.5 - 1 °C / min, and continue stirring and reacting at room temperature for a period of time; (5) After the reaction in step (4) ends, remove volatile substances under reduced pressure, then add hexane or toluene solution to dissolve, filter and extract, collect the filtrate, and obtain the α-diimino dimethyl Fe(III) compound having the structure shown in general formula (I) after repeated recrystallization at -30 °C.

4. The method according to claim 3, wherein In step (1), the molar ratio of the α-diimine compound to metallic lithium is 1:1.0 - 1.

3.

5. The method according to claim 3, characterized in that, In step (1), the mass ratio of the α-diimine compound to tetrahydrofuran is 1:10 - 1:20; in step (2), the mass ratio of ferric chloride to tetrahydrofuran is 1:10 - 1:

20.

6. The method according to claim 3, wherein In step (1), the molar ratio of the α-diimine compound to ferric chloride in step (2) is 1:0.9 - 1.

1.

7. The method according to any one of claims 3-6, characterized in that In step (4), the molar ratio of methyllithium to ferric chloride in step (2) is 2:(0.9 - 1.1).

8. The application of the α-diimino dimethyl Fe(III) compound according to claim 1 or 2 in the field of preparation of microelectronic materials.

9. The application of the α-diimino dimethyl Fe(III) compound according to claim 1 or 2 in the field of preparation of Fe-based thin film materials.

10. The application according to claim 8 or 9, characterized in that, The said application uses the α-diimino dimethyl Fe(III) compound according to claim 1 or 2 as a precursor to prepare a metal or metal alloy thin film by chemical vapor deposition process or atomic layer deposition process.

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