Precursor alpha-aldimine Fe (II) compound for magnetic random storage material

Abstract

The invention discloses a precursor alpha-aldimine Fe (II) compound for a magnetic random storage material, and belongs to the technical field of functional materials and microelectronic materials. The structural formula of the alpha-aldimine Fe (II) compound disclosed by the invention is as shown in a formula I; the Fe-based thin film has good volatility and thermal stability and good film forming performance, can be used as a precursor of chemical vapor deposition (CVD) / atomic layer deposition (ALD), and is continuous, uniform and high in purity through a CVD / ALD process. # imgabs0 #

Description

Technical Field

[0001] The invention relates to a precursor alpha-aldimine Fe (II) compound for magnetic random storage material, belonging to the technical field of functional materials and microelectronic materials. Background Art

[0002] With the development of the Internet, the Internet of Things and big data, information storage technology is also 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 research and development efforts in this regard. Among them, magnetic random access storage technology uses a device with a large magnetoresistance effect to store data in a stable magnetic state. The data is read out by measuring the resistance of the device. Compared with other random access storage technologies, it has obvious advantages such as high integration, high-speed reading and writing capabilities, nearly infinite repeated read and write times, low power consumption and high radiation resistance, and the most prominent non-volatility. The key to the development of magnetic random access storage technology lies in the development of magnetic random access storage materials.

[0003] At present, magnetic random access memory materials are mainly composed of appropriate ferromagnetic materials and their alloys, which mainly include Fe-based metal Fe, CoFe, NiFe, CoFeB, FeOx and other metal or metal alloy thin film materials.

[0004] Traditional preparation methods of magnetic random access memory materials mainly include magnetron sputtering, molecular beam epitaxy, pulsed laser deposition and other methods; however, with the continuous reduction of the characteristic size of microelectronic devices and the continuous increase of the aspect ratio of the device structure, material filling faces great difficulties. The traditional deposition method (depositing materials faster at the opening of the groove and slower at the bottom of the groove, which will lead to poor step coverage at the bottom of the groove and cause device failure) can no longer meet the requirements; chemical vapor deposition (CVD) and atomic layer deposition (ALD) technology have become new device manufacturing technologies due to their own advantages in good conformality and uniformity. In CVD / ALD process technology, the properties of the precursor are crucial, requiring the precursor to have excellent volatility, thermal stability and reactivity; it also needs to have high purity, easy storage, non-toxicity, easy synthesis, low price, 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.

[0005] At present, the iron precursors that can be used for the preparation of metallic iron and related thin films by CVD / ALD technology still have one or more of the following problems:

[0006] Volatility is too low;

[0007] It is prone to spontaneous combustion and is highly toxic, which increases the danger of its use;

[0008] The thermal stability is too low, it is easy to decompose / volatize and cannot be stored for a long time;

[0009] The prepared film tends to have a higher carbon content and the like.

[0010] At the same time, different precursors will directly affect the composition and properties of the final thin film materials due to their own structure and process parameters.

[0011] At present, the types and quantities of Fe precursors developed are relatively small, which is not enough to meet the huge demand for the preparation of materials of different types and performances. Therefore, under the background of continuous upgrading of related technical fields, it is very important to explore and synthesize more types of CVD / ALD Fe precursors to meet the increasing / improving needs. Summary of the invention

[0012] [Technical issues]

[0013] There are still some problems with iron precursors that can be used to prepare metallic iron and related thin films using CVD / ALD technology, such as: too low thermal stability and low volatility.

[0014] The types and quantities of Fe precursors that can be applied to CVD / ALD technology are relatively small.

[0015] [Technical solution]

[0016] In order to solve the above problems, the present invention provides an α-aldimine Fe(II) compound as a precursor for magnetic random access memory materials; and the synthesis method thereof is simple and the conditions are mild; it has good solubility in organic solvents such as n-hexane, toluene, ether, dichloromethane, tetrahydrofuran, etc., has good volatility and thermal stability, forms a film continuously and uniformly, and has good film-forming properties.

[0017] The first object of the present invention is to provide an α-aldimine Fe (II) compound, the structural formula of which is as follows:

[0018]

[0019] 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 or -Si(R 1 )3, R 1 It is a C1-C6 alkyl group.

[0020] In one embodiment of the present invention, the structural formula of the α-aldimine Fe(II) compound is as follows:

[0021]

[0022] A second object of the present invention is to provide a method for preparing an α-aldimine Fe (II) compound, comprising the steps of:

[0023] (1) dissolving an α-aldimine compound or a derivative thereof in ether, adding metallic lithium under stirring at -78 to 0°C, then returning to room temperature and continuing to stir for 24 to 48 hours to obtain a reaction mixture;

[0024] (2) dissolving ferric chloride in ether to obtain a ferric chloride ether solution;

[0025] (3) adding the reaction mixture to a solution of ferric chloride in ether at -78°C, slowly heating the mixture to room temperature, and continuing to stir the reaction at room temperature for 10 to 24 hours;

[0026] (4) After the reaction is completed, the volatile matter is removed; then a solvent is added to dissolve the mixture, the mixture is filtered and extracted, the filtrate is collected, and the mixture is recrystallized to obtain an α-aldimine Fe(II) compound.

[0027] In one embodiment of the present invention, the α-aldimine compound in step (1) is one or more of tert-butyl α-aldimine, phenyl α-aldimine, and trimethylsilyl α-aldimine.

[0028] In one embodiment of the present invention, in step (1), the mass ratio of the α-aldimine compound or its derivative to diethyl ether is 1:10 to 1:20.

[0029] In one embodiment of the present invention, the stirring speed in step (1) is 100 to 1000 rpm.

[0030] In one embodiment of the present invention, in step (1), the molar ratio of the α-aldimine compound or its derivative to metallic lithium is 1:1 to 1:1.2.

[0031] In one embodiment of the present invention, the room temperature in step (1) is 20-30°C.

[0032] In one embodiment of the present invention, the mass ratio of ferric chloride to diethyl ether in step (2) is 1:10 to 1:20.

[0033] In one embodiment of the present invention, the molar ratio of the α-aldimine or its derivative in the reaction mixture to the ferric chloride in the ferric chloride ether solution in step (3) is 2:(0.9-1.1).

[0034] In one embodiment of the present invention, the reaction mixture in step (3) is added with ferric chloride ether solution at one time.

[0035] In one embodiment of the present invention, the heating rate in step (3) is 0.5-1°C / min.

[0036] In one embodiment of the present invention, the room temperature in step (3) is 20-30°C.

[0037] In one embodiment of the present invention, the stirring speed in step (3) is 100 to 1000 rpm.

[0038] In one embodiment of the present invention, the volatiles are removed in step (4) by reducing pressure.

[0039] In one embodiment of the present invention, the solvent in step (4) is hexane or toluene.

[0040] In one embodiment of the present invention, the recrystallization in step (4) is repeated recrystallization at -30°C.

[0041] In one embodiment of the present invention, the synthetic route of the method for preparing α-aldimine Fe (II) compounds is as follows:

[0042]

[0043] The third object of the present invention is to provide a magnetic random information storage material, which uses the α-aldimine Fe(II) compound described in the present invention.

[0044] The fourth object of the present invention is to provide a CVD deposited Fe-based film, which uses the α-aldimine-based Fe(II) compound described in the present invention.

[0045] The fifth object of the present invention is to provide a method for CVD deposition of Fe-based thin films, wherein the method uses an α-aldimine Fe (II) compound 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: 300-400°C, and film formation rate: 4.6-8.1 nm / min.

[0046] A sixth object of the present invention is to provide a method for improving the volatility and thermal stability of a CVD Fe precursor, wherein the method uses the α-aldimine Fe(II) compound of the present invention.

[0047] The seventh objective of the present invention is the application of the α-aldimine Fe (II) compound and CVD deposited Fe-based film described in the present invention in the field of microelectronic material preparation.

[0048] In one embodiment of the present invention, the application is for preparing magnetic random information storage materials.

[0049] In one embodiment of the present invention, the application is to use the above-mentioned α-aldimine Fe(II) compound as a precursor to prepare a metal or metal alloy film through a chemical vapor deposition process or an atomic layer deposition process.

[0050] [Beneficial Effects]

[0051] (1) The α-aldimine Fe(II) compound of the present invention can be used as a precursor for CVD / ALD to prepare Fe-based thin films such as FeO by chemical vapor deposition (CVD) or atomic layer deposition (ALD) process. X membrane.

[0052] (2) The α-aldimine Fe(II) compound of the present invention has the following advantages:

[0053] The synthesis method is simple and the conditions are mild, which greatly reduces the synthesis cost of precursor materials;

[0054] It has good solubility in organic solvents such as n-hexane, toluene, ether, dichloromethane, tetrahydrofuran, etc., making the transportation, delivery and processing of the precursor simple and easy to operate;

[0055] It has good volatility and thermal stability. For example, after testing the thermal properties of the precursor by thermogravimetric (TG) method, the T of the bis(tert-butyl-α-aldimine)-based Fe(II) precursor at normal pressure is 50 is 214.8℃, and the minimum residual mass is 6.74%;

[0056] It has good film-forming properties. Taking the bis(tert-butyl-α-aldimine)-based Fe(II) precursor as an example, with N2 as the carrier gas and O2 as the reaction gas, a continuous, uniform, and high-purity CVD FeO can be formed at 300°C. X membrane. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 This is a single crystal structure diagram of the bis(tert-butyl-α-aldimine)-based Fe(II) precursor in Example 1.

[0058] Figure 2 It is the TG spectrum of the bis(tert-butyl-α-aldimine)-based Fe(II) precursor in Example 1; wherein the abscissa is temperature, in units of °C; and the ordinate is weight loss rate, in units of %.

[0059] Figure 3 The CVD FeO obtained by using the bis(tert-butyl-α-aldimine)-based Fe(II) precursor in Example 2X SEM images of membrane materials.

[0060] Figure 4 The CVD FeO obtained by using the bis(tert-butyl-α-aldimine)-based Fe(II) precursor in Example 2 X XPS graph of the membrane material. DETAILED DESCRIPTION

[0061] The preferred embodiments of the present invention are described below. It should be understood that the embodiments are for better explaining the present invention and are not used to limit the present invention.

[0062] Example 1

[0063] A method for preparing an α-aldimine Fe(II) compound comprises the following steps:

[0064] (1) dissolving tert-butyl α-aldimine in ether at a mass ratio of 1:20, adding metallic lithium at -78°C with stirring (600 rpm), and continuing to stir and react for 24 hours after returning to room temperature to obtain a reaction mixture; wherein the molar ratio of tert-butyl α-aldimine to metallic lithium is 1:1;

[0065] (2) dissolving ferric chloride in diethyl ether at a mass ratio of ferric chloride to diethyl ether of 1:20 to obtain a ferric chloride diethyl ether solution;

[0066] (3) adding the reaction mixture of step (1) to the ferric chloride ether solution of step (2) at -78°C, slowly heating to room temperature at a heating rate of 1°C / min, and continuing to stir (600 rpm) at room temperature for 15 hours; wherein the molar ratio of tert-butyl α-aldimine in the reaction mixture to ferric chloride in the ferric chloride ether solution is 2:1;

[0067] (4) After the reaction is completed, the volatile matter is removed by reducing the pressure, and then a hexane solution is added to dissolve, filtered and extracted, and the filtrate is collected and repeatedly recrystallized at -30°C to obtain the target product (di-tert-butyl α-aldehyde imine iron precursor).

[0068] The obtained target product was subjected to performance test, and the test results are as follows:

[0069] The yield of the target product was 79%.

[0070] The elemental analysis of the target product is: C, 51.16; H, 7.98; N, 9.81, Fe, 19.63; the theoretical elemental analysis value is C, 51.08; H, 7.86; N, 9.93; Fe, 19.79.

[0071] The single crystal X-ray diffraction analysis of the target product is as follows: Figure 1 ;from Figure 1 It can be seen that the structural formula of the target product is as follows:

[0072]

[0073] The target product (di-tert-butyl α-aldimine iron precursor) has good solubility in organic solvents such as n-hexane, toluene, ether, dichloromethane, tetrahydrofuran, etc., making the transportation, delivery and processing of the precursor simple and easy to operate; the thermal properties of the precursor were tested by thermogravimetric (TG) method, and the T of the target product (di-tert-butyl α-aldimine iron precursor) under normal pressure was 50 is 214.86℃, the minimum residual mass is 6.74%, the results are shown in Figure 2 , has good volatility and thermal stability.

[0074] Example 2

[0075] A CVD deposited Fe-based FeO X The method of the film comprises the following steps:

[0076] The target product of Example 1 (di-tert-butyl α-aldimine iron precursor) is used as a precursor;

[0077] The growth parameters used in the CVD deposition process are:

[0078] Total pressure 15 torr, N2 flow: 120 mL / min, O2: 100 mL / min, deposition time: 30 min, deposition temperature: 300 ° C, film formation rate: 8.1 nm / min.

[0079] The obtained CVD FeO X The membrane was tested for performance, and the results were as follows Figure 3 and Figure 4 ;

[0080] from Figure 3 It can be seen that: CVD FeO X The film is continuous and uniform.

[0081] from Figure 4 It can be seen that: CVD FeO X The membrane has high purity.

[0082] Example 3

[0083] A method for preparing an α-aldimine Fe(II) compound comprises the following steps:

[0084] (1) dissolving phenyl α-aldimine in ether at a mass ratio of 1:25, adding metallic lithium at -78°C with stirring (600 rpm), and continuing to stir and react for 48 hours after returning to room temperature to obtain a reaction mixture; wherein the molar ratio of phenyl α-aldimine to metallic lithium is 1:1.2;

[0085] (2) dissolving ferric chloride in diethyl ether at a mass ratio of ferric chloride to diethyl ether of 1:25 to obtain a ferric chloride diethyl ether solution;

[0086] (3) adding the reaction mixture of step (1) to the ferric chloride ether solution of step (2) at -78°C, slowly heating to room temperature at a heating rate of 0.5°C / min, and continuing to stir (600 rpm) at room temperature for 15 hours; wherein the molar ratio of phenyl α-aldimine in the reaction mixture to ferric chloride in the ferric chloride ether solution is 2:1;

[0087] (4) After the reaction is completed, the volatile matter is removed by reducing the pressure, and then a hexane solution is added to dissolve, filtered and extracted, and the filtrate is collected and repeatedly recrystallized at -30°C to obtain the target product (bisphenyl α-aldehyde imine iron precursor).

[0088] The obtained target product was subjected to performance test, and the test results are as follows:

[0089] The structural formula of the target product is:

[0090]

[0091] Yield of target product: 74%, melting point: 96-17.7°C.

[0092] Elemental analysis of the target product: C, 59.55; H, 4.58; N, 8.61, Fe, 17.22; the theoretical elemental analysis value is C, 59.66; H, 4.38; N, 8.70; Fe, 17.34.

[0093] The target product (bisphenyl α-aldehyde imine iron precursor) has good solubility in organic solvents such as n-hexane, toluene, ether, dichloromethane, tetrahydrofuran, etc., making the transportation, delivery and processing of the precursor simple and easy to operate;

[0094] The thermal properties of the precursor were tested by thermogravimetric (TG) method. The T 50 The temperature is 253.7℃, the minimum residual mass is 7.13%, and it has good volatility and thermal stability.

[0095] Example 4

[0096] A CVD deposited Fe-based FeO X The method of the film comprises the following steps:

[0097] The target product of Example 3 (bisphenyl α-aldehyde imine iron precursor) is used as a precursor;

[0098] The growth parameters used in the CVD deposition process are:

[0099] Total pressure is 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.

[0100] The obtained CVD FeO X The membrane was tested for performance and the results are as follows;

[0101] CVD FeO X The membrane is continuous, uniform and of high purity.

[0102] Example 5

[0103] A method for preparing an α-aldimine Fe(II) compound comprises the following steps:

[0104] (1) dissolving trimethylsilyl α-aldimine in ether at a mass ratio of trimethylsilyl α-aldimine to ether of 1:15, adding metallic lithium at -78°C with stirring (800 rpm), and continuing to stir and react for 30 hours after returning to room temperature to obtain a reaction mixture; wherein the molar ratio of trimethylsilyl α-aldimine to metallic lithium is 1:1.1;

[0105] (2) dissolving ferric chloride in diethyl ether at a mass ratio of ferric chloride to diethyl ether of 1:15 to obtain a ferric chloride diethyl ether solution;

[0106] (3) adding the reaction mixture of step (1) to the ferric chloride ether solution of step (2) at -78°C, slowly heating to room temperature at a heating rate of 0.5°C / min, and continuing to stir (800 rpm) at room temperature for 20 hours; wherein the molar ratio of trimethylsilyl α-aldimine in the reaction mixture to ferric chloride in the ferric chloride ether solution is 2:1;

[0107] (4) After the reaction is completed, the volatile matter is removed by decompression, and then a hexane solution is added to dissolve, filtered and extracted, and the filtrate is collected and repeatedly recrystallized at -30°C to obtain the target product (bistrimethylsilyl α-aldehyde imine iron precursor).

[0108] The obtained target product was subjected to performance test, and the test results are as follows:

[0109] The structural formula of the target product is:

[0110]

[0111] Yield of target product: 51%.

[0112] Elemental analysis of the target product: C, 38.35; H, 7.17; N, 8.76, Fe, 17.62; the theoretical elemental analysis values ​​are C, 38.21; H, 7.06; N, 8.91; Fe, 17.77.

[0113] The target product (bistrimethylsilyl α-aldimine iron precursor) has good solubility in organic solvents such as n-hexane, toluene, ether, dichloromethane, tetrahydrofuran, etc., making the transportation, delivery and processing of the precursor simple and easy to operate;

[0114] The thermal properties of the precursor were tested by thermogravimetric (TG) method. The T 50 The temperature is 243.6℃, ​​the minimum residual mass is 6.19%, and it has good volatility and thermal stability.

[0115] Example 6

[0116] A CVD deposited Fe-based FeO X The method of the film comprises the following steps:

[0117] The target product of Example 5 (bistrimethylsilyl α-aldehyde imine iron precursor) is used as a precursor;

[0118] The growth parameters used in the CVD deposition process are:

[0119] Total pressure is 15 torr, N2 flow rate: 120 mL / min, O2: 100 mL / min, deposition time: 30 min, deposition temperature: 400 °C, and film formation rate: 4.6 nm / min.

[0120] The obtained CVD FeO X The membrane was tested for performance and the results are as follows;

[0121] CVD FeO X The membrane is continuous, uniform and of high purity.

[0122] Comparative Example 1

[0123] The Fe complex containing O-type ligands, ferrous acetylacetonate, is used as a precursor for CVD / ALD thin film deposition, wherein the structure of the ferrous acetylacetonate complex is as follows:

[0124]

[0125] The properties were compared with those of the precursor in Example 1, and the results were as follows:

[0126] The precursor has poor thermal volatility and thermal stability and is easily decomposed during storage, which increases the difficulty of the operation, transportation, delivery and processing of the precursor and is not conducive to industrial application.

[0127] Comparative Example 2

[0128] Ferrocene complex is used as a precursor for CVD / ALD thin film deposition; wherein the structure of ferrocene complex is as follows:

[0129]

[0130] The properties of the CVD film prepared by using the precursor in Example 1 were compared, and the results were as follows:

[0131] Although the precursor has high volatility and thermal stability, the film prepared by using the precursor tends to have a high impurity content, which is not conducive to industrial application.

[0132] Although the present invention has been disclosed as above in the form of a preferred embodiment, it is not intended to limit the present invention. Anyone familiar with this technology can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be based on the definition of the claims.

Claims

1. An α-aldimine Fe(II) compound, characterized in that The structural formula is as follows: 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 or -Si(R 1 )3, R 1 It is a C1-C6 alkyl group.

2. The α-aldimine Fe(II) compound according to claim 1, characterized in that The structural formula of α-aldimine Fe(II) compounds is as follows:

3. A method for preparing the α-aldimine Fe(II) compound according to claim 1 or 2, characterized in that: The steps include: (1) dissolving an α-aldimine compound or a derivative thereof in ether, adding metallic lithium under stirring at -78 to 0°C, then returning to room temperature and continuing to stir for 24 to 48 hours to obtain a reaction mixture; (2) dissolving ferric chloride in ether to obtain a ferric chloride ether solution; (3) adding the reaction mixture to a solution of ferric chloride in ether at -78°C, slowly heating the mixture to room temperature, and continuing to stir the reaction at room temperature for 10 to 24 hours; (4) After the reaction is completed, the volatile matter is removed; then a solvent is added to dissolve the mixture, the mixture is filtered and extracted, the filtrate is collected, and the mixture is recrystallized to obtain an α-aldimine Fe(II) compound.

4. The method according to claim 3, characterized in that The α-aldimine compound in step (1) is one or more of tert-butyl α-aldimine, phenyl α-aldimine and trimethylsilyl α-aldimine.

5. The method according to claim 3, characterized in that: In step (3), the molar ratio of α-aldimine or its derivative in the reaction mixture to ferric chloride in the ferric chloride ether solution is 2:(0.9-1.1).

6. A magnetic random information storage material, characterized in that: The method uses the α-aldimine Fe(II) compound according to claim 1 or 2.

7. A CVD deposited Fe-based thin film, characterized in that: The method uses the α-aldimine Fe(II) compound according to claim 1 or 2.

8. A method for depositing a Fe-based thin film by CVD, characterized in that: The method described is to use the α-aldimine Fe(II) compound described in claim 1 or 2 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: 300-400°C, and film formation rate: 4.6-8.1 nm / min.

9. A method for improving the volatility and thermal stability of a CVD Fe precursor, characterized in that: The method uses the α-aldimine Fe(II) compound according to claim 1 or 2.

10. Use of the α-aldimine Fe(II) compound according to claim 1 or 2 and the CVD deposited Fe-based film according to claim 7 in the field of microelectronic material preparation.

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