A yttrium precursor, a synthesis method and application thereof

Abstract

The application discloses a yttrium precursor, a synthesis method and application thereof, and belongs to the field of organic synthesis. The synthesis method of the yttrium precursor comprises the following steps: dissolving sodium hydroxide in an organic solvent, dissolving 2,2,6,6-tetramethyl-3,5-octanedione in the organic solvent, adding the 2,2,6,6-tetramethyl-3,5-octanedione dropwise into the sodium hydroxide solution, and stirring to react after the dropwise adding is completed; dissolving yttrium nitrate hexahydrate in an organic solvent, adding the yttrium nitrate hexahydrate dropwise into the mixed solution, stirring to react at room temperature after the dropwise adding is completed, adding pure water after the reaction is completed, precipitating a solid, filtering, washing and drying to obtain the product. The application synthesizes a novel yttrium precursor Y(tmod)3 which has good thermal stability, good volatility and low melting point. The yttrium oxide thin film prepared by using the precursor has a high film forming rate and high film purity.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of organic synthesis, and particularly relates to a yttrium precursor, a synthesis method and application thereof. BACKGROUND

[0002] Yttrium oxide film has been widely used in integrated circuits, catalysts, protective coating materials, optical devices and the like due to its excellent chemical stability, electrochemical and optical properties. In the field of integrated circuits, the high dielectric constant (14-18), high refractive index (1.9-2.0), wide energy band gap (5.8 eV) and high breakdown voltage (> 3 MVcm -1 ) of the yttrium oxide film make it an ideal high-K material.

[0003] The production technology of the yttrium oxide film includes sputtering deposition, metal organic chemical vapor deposition (MOCVD) and atomic layer deposition (ALD). In recent years, the ALD technology is mainly applied to the preparation of high-quality films in the microelectronic field. In atomic layer deposition, the reactants are injected into the reaction chamber in a non-overlapping alternating manner, and based on the principle of self-limiting surface chemical reaction, precise film thickness control can be achieved. In addition, the temperature requirement of the deposition process is usually lower than that of other methods, the film uniformity is good, and the technology is widely compatible.

[0004] The yttrium precursor used in the deposition of the yttrium oxide film by the ALD technology has high requirements. The reported yttrium precursors include amidine yttrium and its derivatives, such as Y(iPr2-amd)3, Y(iPrCp)2(iPr-amd) and the like. The precursors have high activity, but poor thermal stability, low synthesis yield, air sensitivity and high nitrogen residue in the film. Cyclopentadienyl yttrium and its derivatives, such as Y(Cp)3, Y(MeCp)3 and the like, have good activity and thermal stability, but the synthesis is complex, the yield is low, the precursors are air sensitive, and the carbon residue in the film is high. In comparison, beta-diketone yttrium and its derivatives, such as Y(tmhd)3, are ideal yttrium precursors, which are simple to synthesize, air stable, have good thermal stability and are easy to obtain raw materials. However, the melting point of the beta-diketone yttrium and its derivatives is high, and the volatility is poor, which may result in slow film forming rate and high carbon residue in the film. Therefore, there is an urgent need for a yttrium precursor with good thermal stability, air stability, good volatility and high film forming performance, and a high-quality yttrium oxide film. SUMMARY

[0005] The present application provides a yttrium precursor and a synthesis method thereof. The present application synthesizes a novel yttrium precursor Y(tmod)3 with good thermal stability, good volatility and low melting point. The yttrium precursor is used to prepare a yttrium oxide film, which has a fast film forming rate and high film purity.

[0006] The present application also provides the application of the yttrium precursor.

[0007] Technical solution: In order to achieve the above-mentioned purpose, the structure of the yttrium precursor is as follows:

[0008] .

[0009] The synthesis method of the yttrium precursor comprises the following steps:

[0010] (1) Dissolve sodium hydroxide in an organic solvent, then dissolve 2,2,6,6-tetramethyl-3,5-octanedione in the organic solvent, add the above-mentioned sodium hydroxide solution, and stir to react;

[0011] (2) Dissolve yttrium nitrate hexahydrate in an organic solvent, add the above-mentioned mixed solution, stir to react, after the reaction is completed, add pure water, and solid is precipitated, then filter, wash and dry to obtain the product Y(tmod)3.

[0012] In step (1), the mass ratio of sodium hydroxide to 2,2,6,6-tetramethyl-3,5-octanedione is 1:3-10.

[0013] As a preferred, the mass ratio of sodium hydroxide to 2,2,6,6-tetramethyl-3,5-octanedione is 1:5.

[0014] In step (1), the organic solvent is any one of methanol, ethanol, toluene and xylene.

[0015] As a preferred, the organic solvent in step (1) is methanol.

[0016] In step (1), the reaction is carried out at room temperature, and the reaction time is 1-2h.

[0017] As a preferred, the reaction in step (1) is carried out at room temperature, and the reaction time is 1h.

[0018] In step (2), the mass ratio of yttrium nitrate hexahydrate to 2,2,6,6-tetramethyl-3,5-octanedione is 3-5:6.

[0019] As a preferred, the mass ratio of yttrium nitrate hexahydrate to 2,2,6,6-tetramethyl-3,5-octanedione in step (2) is 192:300.

[0020] In step (2), the organic solvent is any one of methanol, ethanol, toluene and xylene.

[0021] As a preferred, the organic solvent in step (2) is methanol.

[0022] In step (2), the reaction is carried out at room temperature, and the reaction time is 8-10h.

[0023] Preferably, the reaction in step (2) is carried out at room temperature, and the reaction time is 8 hours.

[0024] The yttrium precursor synthesized by the synthesis method of the yttrium precursor is applied to the preparation of yttrium oxide thin films.

[0025] The application is to deposit yttrium oxide thin films on a silicon dioxide substrate by an atomic layer deposition process using Y(tmod)3 as a precursor.

[0026] The atomic layer deposition is to set the Y(tmod)3 source bottle at 90-120 DEG C, the deposition temperature is 250-350 DEG C, high-purity argon or nitrogen is used as the carrier gas and the purge gas; one complete ALD cycle includes the alternating pulses of the yttrium precursor and ozone, plasma oxygen, oxygen, water, alcohol or hydrogen peroxide, the pulse time of Y(tmod)3 is set to 3-10 s, the pulse time and the cleaning time of the oxygen source are both set to 4-6 s, and the cycle number is set to 1000-1500 cycles.

[0027] Preferably, the atomic layer deposition is to set the Y(tmod)3 source bottle at 100 DEG C, the deposition temperature is 270 DEG C, high-purity argon or nitrogen is used as the carrier gas and the purge gas; one complete ALD cycle includes the alternating pulses of the yttrium precursor and ozone, plasma oxygen, oxygen, water, alcohol or hydrogen peroxide, the pulse time of Y(tmod)3 is set to 5 s, the pulse time and the cleaning time of the oxygen source are both set to 4 s, and the cycle number is set to 1000 cycles.

[0028] At present, amidinyl yttrium and its derivatives are used to prepare yttrium oxide thin films. For example, Y(iPr2-amd)3, Y(iPrCp)2(iPr-amd) and the like. Such precursors have high activity, but poor thermal stability, low synthesis yield, air sensitivity and high nitrogen residue in the thin film. Cyclopentadienyl yttrium and its derivatives are used to prepare yttrium oxide thin films. For example, Y(Cp)3, Y(MeCp)3 and the like. Such precursors have good activity and thermal stability, but complex synthesis, low yield, air sensitivity and high carbon residue in the thin film. Beta-diketone yttrium and its derivatives are used to prepare yttrium oxide thin films. For example, Y(tmhd)3. The synthesis is simple, the raw material is easy to obtain, it is air stable and has good thermal stability, and it is an ideal yttrium precursor. However, it has a high melting point and poor volatility, which may result in slow film forming rate and high carbon residue in the thin film.

[0029] The present application prepares a novel yttrium precursor Y(tmod)3 with good thermal stability, good volatility and low melting point by asymmetric design of ligand and optimization of synthesis route. Through precursor physical property data analysis and thin film preparation process optimization, the yttrium oxide thin film prepared by using the precursor has fast film forming rate and high film purity.

[0030] The application breaks the symmetry of the ligand by introducing methyl on the basis of the commercial precursor, so that the volatility is higher, the melting point is lower, the carbon content in the thin film is reduced in the thin film deposition application, and the purity of the prepared thin film is high.

[0031] Beneficial effects: Compared with the prior art, the application has the following remarkable advantages:

[0032] The application provides a novel yttrium precursor structure and a synthesis method thereof, the method is simple in operation, short in production period, avoids dangerous materials, high in yield, and suitable for industrial production; meanwhile, the prepared yttrium precursor is good in stability, good in volatility, and low in melting point, the yttrium oxide thin film prepared by using the precursor has a high film forming rate and high thin film purity. DETAILED DESCRIPTION

[0033] The application will be further described below in combination with examples.

[0034] The experimental methods in the examples are all conventional methods unless otherwise specified; and the materials, reagents and the like used in the examples can be obtained from commercial channels unless otherwise specified.

[0035] Y(tmod )3 The Chinese name of Y(tmod)3 is: yttrium tris(2,2,6,6-tetramethyl-3,5-octanedione), which is synthesized according to the application.

[0036] The Chinese name of Y(tmhd)3 is: yttrium tris(2,2,6,6-tetramethyl-3,5-heptanedione), which is commercially available, and the CAS number is: 15632-39-0, and the melting point is 172-174℃.

[0037] Example 1

[0038] 60g of sodium hydroxide was dissolved in 1.5L of methanol and added to a multi-neck flask at room temperature. 2,2,6,6-tetramethyl-3,5-octanedione 300g was dissolved in 1L of methanol and added dropwise to the above multi-neck flask, and after the dropwise addition was completed, stirring was carried out at room temperature for 1 hour. 192g of yttrium nitrate hexahydrate was dissolved in 1L of methanol and added dropwise to the above multi-neck flask, and after the dropwise addition was completed, reaction was carried out at room temperature for 8 hours. After the reaction was completed, 5L of pure water was added to the reaction flask, and a large amount of solid was precipitated, filtered, washed with pure water three times, and dried to obtain white solid product yttrium precursor Y(tmod)3 (325g, 95.5%). The melting point was tested, and the melting point was 92-94℃.

[0039] The reaction formula is as follows:

[0040]

[0041] 1 H NMR (C6D6): δ = 5.94 (3H, s), 1.59 (6H, q), 1.20 (27H, s), 1.16(18H, s), 0.89 (9H, t).

[0042] Example 2

[0043] Preparation of yttrium oxide film using Y(tmod)3

[0044] The film of this example was deposited on a SiO2 / Si(100) substrate with a SiO2 thickness of about 100 nm. The substrate was cleaned with acetone, isopropanol, and deionized water before use, and then dried with N2.

[0045] A yttrium oxide film was deposited on a SiO2 substrate using Y(tmod)3 prepared in Example 1 as a precursor by an atomic layer deposition process. The atomic layer deposition chamber was heated from room temperature to 270°C and vacuumized. The Y(tmod)3 source bottle was set to 100°C, the deposition temperature was 270°C, and high-purity nitrogen (99.999%) was used as the carrier gas and purge gas. The precursor molecules were introduced into the atomic layer deposition chamber using the carrier gas, and the pulse time was 5 s. After the precursor molecules were pulsed, nitrogen was continuously introduced for 4 s to clean the unreacted precursor and by-products. O3 was then introduced into the deposition chamber using the carrier gas, and the pulse time was 4 s. After the pulse, nitrogen was continuously introduced for 4 s to clean the unreacted precursor and by-products. The above process was repeated, and the number of cycles was set to 1000 cycles to obtain a yttrium oxide film.

[0046] The thickness of the film deposited in this example was measured by ellipsometry to be 29.17 nm, the growth rate was 0.29 Å / cycle, and the carbon impurity content was 0.18% as measured by XPS.

[0047] Example 3

[0048] Preparation of yttrium oxide film using Y(tmod)3

[0049] The film of this example was deposited on a SiO2 / Si(100) substrate with a SiO2 thickness of about 100 nm. The substrate was cleaned with acetone, isopropanol, and deionized water before use, and then dried with N2.

[0050] A Y(tmod)3 prepared in Example 1 was used as a precursor to deposit a yttrium oxide film on a silicon dioxide substrate by an atomic layer deposition process. The atomic layer deposition chamber was heated from room temperature to 270°C and vacuumized; the Y(tmod)3 source bottle was set to 100°C, the deposition temperature was 270°C, and high-purity nitrogen (99.999%) was used as a carrier gas and a purge gas. The precursor molecules were sent into the atomic layer deposition chamber by the carrier gas, and the pulse time was 5 s. After the precursor molecules were pulsed, nitrogen was continuously introduced for 4 s to clean the unreacted precursor and by-products. Plasma oxygen was then sent into the deposition chamber by the carrier gas, and the pulse time was 4 s. After the pulse, nitrogen was continuously introduced for 4 s to clean the unreacted precursor and by-products. The above process was repeated, and the cycle number was set to 1000 cycles to obtain a yttrium oxide film.

[0051] The thickness of the film deposited in this example was measured by ellipsometry to be 27.43 nm, the growth rate was 0.27 Å / cycle, and the carbon impurity content was 0.21% as measured by XPS.

[0052] Comparative Example 1

[0053] The method of Example 2 was used, and Y(tmod)3 in Example 2 was replaced with Y(tmhd)3 to prepare a film. The growth rate of the prepared film was 0.23 Å / cycle, and the carbon impurity content was 0.83% as measured by XPS. The preparation rate and purity of the prepared film were obviously inferior to those of the film prepared in the present application.

Claims

1. A yttrium precursor, characterized by, The structure of the yttrium precursor is shown as follows: 。 2. A method of synthesizing the yttrium precursor of claim 1, characterized in that, The method comprises the following steps: (1) dissolving sodium hydroxide in an organic solvent, dissolving 2,2,6,6-tetramethyl-3,5-octanedione in the organic solvent, adding the sodium hydroxide solution, and stirring to react; (2) dissolving yttrium nitrate hexahydrate in an organic solvent, adding the mixed solution obtained in step (1), stirring to react, adding pure water after the reaction is completed, precipitating a solid, filtering, washing, and drying to obtain the product yttrium precursor.

3. The method for synthesizing the yttrium precursor according to claim 2, characterized in that, The mass ratio of sodium hydroxide to 2,2,6,6-tetramethyl-3,5-octanedione in step (1) is 1:3-10.

4. The method for synthesizing the yttrium precursor according to claim 2, characterized in that, The organic solvent in step (1) is any one of methanol, ethanol, toluene, and xylene.

5. The method for synthesizing the yttrium precursor according to claim 2, characterized in that, The reaction in step (1) is carried out at room temperature, and the reaction time is 1-2 h.

6. The method for synthesizing the yttrium precursor according to claim 2, characterized in that, The mass ratio of yttrium nitrate hexahydrate to 2,2,6,6-tetramethyl-3,5-octanedione in step (2) is 3-5:

6.

7. The method for synthesizing the yttrium precursor according to claim 2, characterized in that, The organic solvent in step (2) is any one of methanol, ethanol, toluene, and xylene.

8. The method for synthesizing the yttrium precursor according to claim 2, characterized in that, The reaction in step (2) is carried out at room temperature, and the reaction time is 8-10 h.

9. Use of the yttrium precursor of claim 1 in the preparation of a yttrium oxide film.

10. Use according to claim 9, characterized in that, The use deposits a yttrium oxide film on a silicon dioxide substrate by an atomic layer deposition process using the yttrium precursor of claim 1 as a precursor.

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