N-alkanoyl alkylamide lanthanum / gadolinium mixed complex as well as preparation method and application thereof

Abstract

The invention discloses an N-alkanoyl alkylamide lanthanum / gadolinium mixed complex as well as a preparation method and application thereof. Under the protection of inert gas, quantitative N-alkanoyl alkylamide and a tris (diamine) lanthanum or tris (diamine) gadolinium compound are added into an anhydrous solvent; adding an anhydrous solvent, reacting for a period of time, filtering, and removing the solvent and byproducts from the filtrate by reduced pressure distillation to obtain a white solid; and recrystallizing and sublimating the obtained white solid to obtain the target metal complex. The complex synthesized by the invention has small pollution to a substrate, the synthesis method is simple and convenient, the process operation is simple, the yield is high, and the cost is low; and the ligand is large in steric hindrance to form a mononuclear compound, has the characteristics of relatively good volatility, proper thermal stability, easiness in synthesis, low toxicity and the like, can be used for preparing a high-K material, and has good practical value and application prospect.

Description

Technical Field

[0001] This invention relates to the field of organometallic complex technology, specifically to an N-alkanoylalkanoamide lanthanum / gadolinium mixed complex, its preparation method, and its application. Background Technology

[0002] With the rapid development of microelectronics technology, from large-scale integrated circuits to very large-scale integrated circuits, the feature size of devices such as transistors is getting smaller and smaller. When the feature size of devices is below 45nm, the traditional gate dielectric material SiO2 can no longer meet the requirements, and high-k materials with higher dielectric constants need to replace SiO2. In recent years, the three most studied high-k materials are ZrO2 (k=25), HfO2 (k=25) and Al2O3 (k=9) (Niinistö L, Päiväsaari J, Niinistö J, et al. phys. stat. sol. (a), 2004, 201(7): 1443~1452.). In addition, rare earth oxides are also a very promising high-k material due to their high stability and excellent electrical properties (Leskelä M, Ritala MJ Solid State Chem., 2003,171(1-2): 170-174.).

[0003] Atomic layer deposition (ALD) is a thin film deposition technology that has developed in recent years. Finding suitable precursors for ALD is crucial. An ideal ALD precursor must meet two basic requirements: (1) Sufficient volatility: ① Large steric hindrance of ligands to prevent aggregation; ② Mononuclear complexes without solvent coordination; ③ Low molecular polarity and weak intermolecular attraction.

[0004] (2) Appropriate reactivity: ① It cannot decompose itself within the deposition temperature range; ② It has high reactivity to oxygen sources (generally H2O); ③ The precursor must be able to adsorb or react with the substrate and will not corrode the substrate.

[0005] Currently, the most studied ALD precursors of oxides can be divided into the following categories: Figure 1 The six categories shown are: alkoxy compounds (A), β-diketone compounds (B), organic amines (C), organometallic compounds (cyclopentadiene-type compounds) (D), amidine complexes (E), and guanidine complexes (F). However, these precursors all have certain drawbacks: Alkoxy compounds have poor thermal stability and low reactivity. They are prone to non-self-limiting thermal decomposition or homogeneous gas-phase reactions at growth temperatures, which can disrupt the ALD process window. Furthermore, their reactivity with water is sometimes insufficient, resulting in low growth rates.

[0006] β-Diketone compounds present a contradiction between volatility and thermal stability. The introduction of sterically hindered ligands (such as thd) can severely reduce reactivity, resulting in high growth temperatures and extremely low growth rates. Incomplete reactions may also introduce carbon impurities. Furthermore, volatility and melting point are sensitive to ligand structure.

[0007] Organic amines, as precursors, have many side reactions. Reaction byproducts (such as amines) may be re-adsorbed, leading to the incorporation of carbon impurities or non-ideal growth. Furthermore, there is the problem of excessive interface cleaning and over-reduction of natural oxides on the substrate surface, such as those of group III-V substrates, which can cause atomic diffusion (such as In and Ga) across the thin film, which is not conducive to interface control.

[0008] Cyclopentadiene-type compounds, when used as precursors, are too large in size and have high steric hindrance, resulting in low growth rates. Furthermore, their ligands are difficult to remove, and even the use of strong oxidants to effectively remove the ligands can damage the film or substrate.

[0009] Amidine complexes contain four-membered rings and exist in equilibrium between monomers and dimers in the solid or in solution, which affects their vapor pressure stability and transport reproducibility.

[0010] Guanidinium complexes have limited sources of ligands (carbodiimides), making their synthesis challenging. Furthermore, the saturated bridging groups in some structures are not conjugated, which can easily lead to the formation of higher-order polymers and reduce volatility. In addition, the size of the substituents within the ring can affect the bond strength and steric repulsion with the metal center, ultimately affecting the film quality.

[0011]

[0012] Furthermore, the existing precursor synthesis processes are relatively cumbersome, the structures are complex, and the prices are high, which hinders their widespread application. Therefore, how to design and develop a high-k material precursor that balances volatility, reactivity, and thermal stability, minimizes substrate contamination, has a simple synthesis method, and is easy to process remains an urgent problem to be solved. Summary of the Invention

[0013] To address the shortcomings of existing technologies and achieve the aforementioned objectives, this invention provides an N-alkanoylalkanoamide lanthanum / gadolinium mixed complex, its preparation method, and its applications. The method uses N-alkanoylalkanoamide and tris(diamine)lanthanum or tris(diamine)gadolinium compounds as raw materials to prepare rare earth hafnium or zirconium metal organic complexes. These complexes, acting as precursors, are alternately pulsed into a reaction chamber with an oxygen source, resulting in a self-limiting surface chemical reaction on the silicon wafer surface. This allows for precise atomic-level control, ensuring a uniform, dense film with excellent shape retention. The specific technical solution is as follows: First, this invention provides an N-alkylalkaneamide lanthanum / gadolinium mixed complex, which has two ligands, an N-alkylalkaneamide and a diamine, and its structural formula is shown in Formula I: (Formula I); In the formula: M =La or Gd; n = 1 or 2; R1=CH3, CF3, CH2CH3, CH2CH2CH3, CHCH3CH3, CH2CH2CH2CH3, CHCH3(CH2CH3), C(CH3)3, Cp or Ph; R2=CH3, CF3, CH2CH3, CH2CH2CH3, CHCH3CH3, CH2CH2CH2CH3, CHCH3(CH2CH3), C(CH3)3, Cp or Ph; R3= -N(CH2CH3)2, -N(CH2CH3)CH3, -N(CH3)2, -N(SiMe3)2.

[0014] Secondly, the present invention provides a method for preparing the aforementioned N-alkylalkanoamide lanthanum / gadolinium mixed complex, comprising the following steps: 1) Under the protection of an inert gas, a quantitative amount of N-alkanoylalkamide and tris(diamine)lanthanum or tris(diamine)gadolinium compound are added to an anhydrous solvent and reacted for a period of time to obtain a crude product solution; 2) Filter the crude product solution obtained in step 1), and remove the solvent and byproducts from the filtrate by vacuum distillation to obtain the crude product solid; 3) The crude product solid obtained by vacuum distillation in step 2) is recrystallized and sublimated to obtain the target metal complex.

[0015] In the aforementioned method for preparing the N-alkanoylalkamide lanthanum / gadolinium mixed complex, in step 1), the inert gas is nitrogen or argon.

[0016] In the aforementioned method for preparing the N-alkanoyl alkanoamide lanthanum / gadolinium mixed complex, in step 1), the ratio of the tris(diamine)lanthanum or tris(diamine)gadolinium compound to the N-alkanoyl alkanoamide is 1:2 or 2:1.

[0017] In the aforementioned method for preparing the N-alkylalkanoamide lanthanum / gadolinium mixed complex, in step 1), the anhydrous organic solvent is selected from any one or two of diethyl ether, ethylene glycol dimethyl ether, tetrahydrofuran, toluene, and n-hexane.

[0018] In the aforementioned method for preparing the N-alkylalkanoamide lanthanum / gadolinium mixed complex, in step 1), the reaction temperature is -10 to 35°C, and the reaction time is 3 to 12 hours.

[0019] In the aforementioned method for preparing the N-alkylalkanoamide lanthanum / gadolinium mixed complex, step 2) involves vacuum distillation with parameters of -50 to -99 kPa and 20 to 100 °C.

[0020] In the aforementioned method for preparing the N-alkyl alkylamide lanthanum / gadolinium mixed complex, step 3) specifically involves recrystallizing the crude product solid obtained by vacuum distillation in the above-mentioned anhydrous organic solvent at a low temperature of -40 to 0°C.

[0021] Furthermore, this invention provides an application of the aforementioned N-alkanoylalkamide lanthanum / gadolinium mixed complex as a precursor for the preparation of high-k materials.

[0022] In this application, the high-k material is prepared using atomic layer deposition (ALD), with the following parameters: Substrate: Si or SiO2; Carrier gas: N2 or Ar; Substrate temperature for the reaction: 260–270 °C; Carrier gas flow rate: 30-50 sccm; The working pressure in the reaction chamber is maintained at 5 × 10⁻⁶ Tor; Within one cycle, the pulse length of the complex precursor is 1.5 s, and the pulse length of H2O is 0.06 s; The growth rate of K material is 0.50 Å / cycle, with 55–65 cycles.

[0023] The beneficial effects of this invention are as follows: 1) The N-alkanoylalkamide hafnium or zirconium mixed complex synthesized in this invention is a novel rare earth metal complex. The ligand has a novel and simple structure, is easy to synthesize, has a stable process, and is inexpensive.

[0024] 2) The N-alkanoylalkamide hafnium or zirconium mixed complex synthesized in this invention combines the advantages of both N-alkanoylalkamide and diamine ligands. The diamine ligand has good vaporization properties, while the N-alkanoylalkamide has large steric hindrance. The steric hindrance of the ligands can be adjusted by regulating the size of the two substituents, which can effectively prevent the formation of polymers in the complex and improve volatility. The N-alkanoylalkamide hafnium or zirconium mixed complex has extremely high reactivity with water and relatively ideal thermal stability. Using it as a precursor to prepare high-k thin film materials not only meets the requirements of the ALD process, but also produces dense, uniform, and smooth high-k thin film materials with good practical value and application prospects. Attached Figure Description

[0025] Figure 1 The structural formulas of ALD precursors for six existing oxides are shown. Figure 2 The structural formula of the N-alkylalkanoamide lanthanum / gadolinium mixed complex of the present invention is shown below; Figure 3 The structural formula of the Gd[NO2C4H6]2[N(SiMe3)2] complex synthesized in Example 1 of this invention is shown below. Figure 4 La[NO2C] synthesized in Example 2 of this invention 12 H 10 Photographs of the [N(SiMe3)2]2 complex; Figure 5 La[NO2C] synthesized in Example 2 of this invention 12 H 10 The structural formula of the [N(SiMe3)2]2 complex; Figure 6 The images show the surface morphology and RMS roughness AFM of the La2O3 thin film prepared in Example 3 of this invention. Detailed Implementation

[0026] To address the shortcomings of existing technologies and to achieve the aforementioned objectives, this invention provides an N-alkanoylalkamide lanthanum / gadolinium mixed complex, its preparation method, and its applications. Rare earth lanthanum or gadolinium metal organometallic complexes are prepared using N-alkanoylalkamides and tris(diamine)lanthanum or tris(diamine)gadolinium compounds as raw materials, with the structural formula shown in Formula I: (Equation I, Figure 2 ); In the formula: M =La or Gd; n = 1 or 2; R1=CH3, CF3, CH2CH3, CH2CH2CH3, CHCH3CH3, CH2CH2CH2CH3, CHCH3(CH2CH3), C(CH3)3, Cp or Ph; R2=CH3, CF3, CH2CH3, CH2CH2CH3, CHCH3CH3, CH2CH2CH2CH3, CHCH3(CH2CH3), C(CH3)3, Cp or Ph; R3= -N(CH2CH3)2, -N(CH2CH3)CH3, -N(CH3)2, -N(SiMe3)2.

[0027] The preparation method of this complex includes the following steps: 1) Under the protection of an inert gas, a measured amount of N-alkanoylalkamide and tris(diamine)lanthanum or tris(diamine)gadolinium compound are added to an anhydrous solvent and reacted for a period of time to obtain a crude product solution; the inert gas is nitrogen or argon; the feed ratio of the tris(diamine)lanthanum or tris(diamine)gadolinium compound to N-alkanoylalkamide is 1:2 or 2:1; the anhydrous organic solvent is selected from any one or two of diethyl ether, ethylene glycol dimethyl ether, tetrahydrofuran, toluene, and n-hexane; the reaction temperature is -10 to 35°C, and the reaction time is 3 to 12 hours; 2) Filter the crude product solution obtained in step 1), and remove the solvent and byproducts from the filtrate by vacuum distillation to obtain the crude product solid; the parameters of the vacuum distillation are -50 to -99 kPa and 20 to 100 °C.

[0028] 3) The crude product solid obtained from vacuum distillation in step 2) is recrystallized and sublimated to obtain the target metal complex; the specific process of recrystallization and sublimation is to recrystallize the crude product solid obtained from vacuum distillation in the above-mentioned anhydrous organic solvent at a low temperature of -40 to 0°C.

[0029] The complex, acting as a precursor, is alternately pulsed into the reaction chamber with an oxygen source, resulting in a self-limiting surface chemical reaction on the silicon wafer surface. This enables precise control at the atomic level, ensuring that the film is uniform, dense, and exhibits excellent shape retention.

[0030] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Specific embodiments are as follows: Example 1: Synthesis of Gd[NO2C4H6]2[N(SiMe3)2] complex Under N2 protection, tris[N,N-bis(trimethylsilyl)amine]Gd[N(SiMe3)2]3 (51.07 g, 0.08 mol) and N-acetylacetamide (16.18 g, 0.16 mol) were dissolved in 200 mL of tetrahydrofuran, and then reacted at 5 °C for 5 h. The solution color changed from colorless to yellow, at which point the reaction was terminated. The reaction solution was filtered under nitrogen protection, and the filtrate was distilled under reduced pressure at -50 kPa and 40 °C for 20 min to remove the solvent and byproducts. Then, it was crystallized in tetrahydrofuran at -25 °C to obtain 35.84 g of white solid, which is the Gd[NO2C4H6]2[N(SiMe3)2] complex, and its structural formula is as follows ( Figure 3 The yield was 86.5%.

[0031]

[0032] Anal. Calcd for C 14 H 30 O4GdN3Si2:Gd, 30.37; C, 32.47; H, 5.84; O, 12.36; N, 8.11, Found: Gd, 30.29; C, 32.28; Example 2: La[NO2C] 12 H 10 Synthesis of [N(SiMe3)2]2 coordination compounds Under Ar protection, tris[N,N-bis(trimethylsilyl)amine]lanthanum La[N(SiMe3)2]3 (43.40 g, 0.07 mol) and N-cyclopentadienoylcyclopentadienylamide (9.16 g, 0.07 mol) were dissolved in 200 mL of diethyl ether and reacted at 15 °C for 10 h. The solution color changed from colorless to pale yellow, at which point the reaction was terminated. The reaction solution was filtered under nitrogen protection, and the filtrate was distilled under reduced pressure at -50 kPa and 20 °C for 30 min to remove the solvent and byproducts. The solution was then recrystallized in diethyl ether at -20 °C to obtain 39.68 g of a white solid. Figure 4 As shown, this is La[NO2C] 12 H 10 The structural formula of the [N(SiMe3)2]2 complex is as follows ( Figure 5 The yield was 85.9%.

[0033]

[0034] Anal. Calcd for C 24 H 46 O2LaN3Si4:La, 21.05; C, 43.68; H, 7.03; O, 4.85; N, 6.37, Found:La, 21.19; C, 43.63; 1 H NMR (300 MHz,C6D6): δ 3.83 (q, 2 H, CHCO-H), δ 6.35 (m, 4H, CHCHCO -H), δ 6.52 (m, 4H, CHCHCO -H), δ 0.09 (s, 36H, N[Si(CH3)3]2). Example 3: Preparation of La2O3 Thin Films This embodiment uses La[NO2C] prepared in Example 2. 12 H 10 La2O3 thin films were grown using atomic layer deposition (ALD) with [N(SiMe3)2]2 as the precursor. The specific details are as follows: substrate: Si wafer; carrier gas: N2; reaction substrate temperature: 265℃; carrier gas flow rate: 40 sccm; reaction chamber working pressure maintained at 5 × 10⁻⁶. -6 Tor; within one cycle, the pulse length of the lanthanum complex precursor is 1.5 s, and the pulse length of H2O is 0.06 s; the growth rate of La2O3 is 0.50 Å / cycle; the cycle lasts for 60 cycles. Figure 6 As shown in the figure, the RMS surface roughness of the La2O3 thin film is 0.845 nm, indicating that the La[NO2C] thin film of this invention... 12 H 10 The thin films prepared by atomic layer deposition technology using the [N(SiMe3)2]2 complex as a precursor are dense, uniform, and have excellent flatness.

[0035] In summary, the ligands of this invention have a novel and simple structure, are easy to synthesize, have a stable process, are inexpensive, cause minimal substrate contamination, and are simple to synthesize, operate, and produce high yields at low cost. Furthermore, the ligands of this invention are sterically hindered, forming mononuclear compounds with good volatility and suitable thermal stability. They are easy to synthesize and have low toxicity. Moreover, they combine the advantages of both N-alkanoylalkamide and diamine ligands. The diamine ligand has good vaporization properties, while the N-alkanoylalkamide has large steric hindrance. The steric hindrance of the ligands can be adjusted by regulating the size of the two substituents, effectively preventing the formation of polymers in the complex and improving volatility. The hafnium or zirconium mixed complex of alkanoylalkamides exhibits extremely high reactivity with water and relatively ideal thermal stability. Using them as precursors to prepare high-k thin film materials not only meets the requirements of the ALD process but also produces dense, uniform, and smooth high-k thin film materials, demonstrating good practical value and application prospects.

[0036] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An N-alkylalkanoamide lanthanum / gadolinium mixed complex, characterized in that: This complex has two ligands: an N-alkyl alkylamide and a diamine, and its structural formula is shown in Formula I: (Formula I); In the formula: M =La or Gd; n = 1 or 2; R1=CH3, CF3, CH2CH3, CH2CH2CH3, CHCH3CH3, CH2CH2CH2CH3, CHCH3(CH2CH3), C (CH3)3, Cp or Ph; R2=CH3, CF3, CH2CH3, CH2CH2CH3, CHCH3CH3, CH2CH2CH2CH3, CHCH3(CH2CH3), C (CH3)3, Cp or Ph; R3= -N(CH2CH3)2, -N(CH2CH3)CH3, -N(CH3)2, -N(SiMe3)2.

2. A method for preparing the N-alkylalkanoamide lanthanum / gadolinium mixed complex according to claim 1, characterized in that: Includes the following steps, 1) Under the protection of an inert gas, a quantitative amount of N-alkanoylalkamide and tris(diamine)lanthanum or tris(diamine)gadolinium compound are added to an anhydrous solvent and reacted for a period of time to obtain a crude product solution; 2) Filter the crude product solution obtained in step 1), and remove the solvent and byproducts from the filtrate by vacuum distillation to obtain the crude product solid; 3) The crude product solid obtained by vacuum distillation in step 2) is recrystallized and sublimated to obtain the target metal complex.

3. The method for preparing the N-alkylalkanoamide lanthanum / gadolinium mixed complex according to claim 1, characterized in that: In step 1), the inert gas is nitrogen or argon.

4. The method for preparing the N-alkylalkanoamide lanthanum / gadolinium mixed complex according to claim 1, characterized in that: In step 1), the ratio of the tris(diamine)lanthanum or tris(diamine)gadolinium compound to N-alkanoylalkamide is 1:2 or 2:

1.

5. The method for preparing the N-alkylalkanoamide lanthanum / gadolinium mixed complex according to claim 1, characterized in that: In step 1), the anhydrous organic solvent is selected from any one or two of diethyl ether, ethylene glycol dimethyl ether, tetrahydrofuran, toluene, and n-hexane.

6. The method for preparing the N-alkylalkanoamide lanthanum / gadolinium mixed complex according to claim 1, characterized in that: In step 1), the reaction temperature is -10 to 35°C, and the reaction time is 3 to 12 hours.

7. The method for preparing the N-alkylalkanoamide lanthanum / gadolinium mixed complex according to claim 1, characterized in that: In step 2), the parameters for vacuum distillation are -50 to -99 kPa and 20 to 100 °C.

8. The method for preparing the N-alkylalkanoamide lanthanum / gadolinium mixed complex according to claim 1, characterized in that: In step 3), the specific process of recrystallization and sublimation is to recrystallize the crude product solid obtained by vacuum distillation in the anhydrous organic solvent described in claim 5 at a low temperature of -40 to 0°C.

9. An application of the N-alkylalkanoamide lanthanum / gadolinium mixed complex according to claim 1, characterized in that: It is used as a precursor for the preparation of high-k materials.

10. The application of the N-alkanoylalkamide lanthanum / gadolinium mixed complex according to claim 9, characterized in that: The method for preparing high-k materials is atomic layer deposition, and its parameters are as follows: Substrate: Si or SiO2; Carrier gas: N2 or Ar; Substrate temperature for the reaction: 260–270 °C; Carrier gas flow rate: 30-50 sccm; The working pressure in the reaction chamber is maintained at 5 × 10⁻⁶ Tor; Within one cycle, the pulse length of the complex precursor is 1.5 s, and the pulse length of H2O is 0.06 s; The growth rate of K material is 0.50 Å / cycle, with 55–65 cycles.

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