Preparation method of yttrium precursor

Abstract

This application discloses a method for preparing a yttrium precursor having the structure shown in general formula 1. The preparation method includes: reacting a compound having general formula 2 with a base to obtain a first intermediate compound having general formula 3; reacting the first intermediate compound with anhydrous yttrium halide to obtain a second intermediate compound having general formula 4; and reacting the second intermediate compound with a compound having general formula 5 to obtain the yttrium precursor. This application employs a trisubstituted synthetic route, causing yttrium halide to undergo a quantitatively complete tricoordinate salt metathesis reaction with a substituted cyclopentadienyl alkali metal salt to generate a single homo-trisubstituted yttrium cyclopentadienyl yttrium intermediate. Subsequently, the intermediate undergoes a monoligand dissociation-exchange reaction with an amidine ligand to obtain the target disubstituted yttrium cyclopentadienyl yttrium heteroligand precursor. This method precisely controls the substitution amount, avoids the generation of byproducts, improves reaction selectivity, and increases the purity and yield of the target product, meeting the requirements of advanced semiconductor processes.

Description

Technical Field

[0001] This application belongs to the field of semiconductor precursor preparation technology, specifically relating to a method for preparing a yttrium precursor. Background Technology

[0002] Yttrium-based precursors are the core raw materials for preparing Y2O3 functional thin films. Their physicochemical properties directly determine the stoichiometry, purity, crystallinity, and overall device-level performance of the thin films. They are currently the core bottleneck restricting the large-scale mass production and application of Y2O3 functional thin films in advanced semiconductor processes. Currently reported yttrium precursors for Y₂O₃ thin film preparation are mainly homogeneous complexes, primarily classified into three categories: O-coordinated, N-coordinated, and cyclopentadienyl-coordinated. Among them, O-coordinated yttrium precursors are solid complexes with low reactivity, requiring the use of strong oxidants such as ozone. Y₂O₃ thin films prepared with N-coordinated yttrium precursors have a yttrium-to-oxygen ratio close to 1:2, which deviates significantly from the ideal stoichiometric ratio of 2:3, directly degrading dielectric properties. Furthermore, the films are highly hygroscopic, requiring additional capping layer deposition or high-temperature annealing, increasing process complexity and mass production costs. Cyclopentadienyl-coordinated yttrium precursors have an extremely narrow ALD process window, poor thermal stability, and are prone to self-decomposition, making stable self-limiting growth impossible and limiting industrial applications.

[0003] To address the problems associated with homogeneous yttrium precursors, the development of novel heterogeneous yttrium precursors has become a key research direction in the industry. However, when preparing heterogeneous yttrium precursors with disubstituted cyclopentadienyl groups using existing technologies, it is difficult to precisely control the substitution amount of the cyclopentadienyl group, which easily generates monosubstituted and trisubstituted cyclopentadienyl yttrium byproducts. The reaction selectivity of the target disubstituted cyclopentadienyl yttrium intermediate is extremely poor, with incomplete main reactions and low feed conversion rates, directly leading to low yields of the subsequent target heterogeneous precursor products and the inability to stably obtain the target product in a room-temperature liquid state. In addition, the side reactions in the synthetic route are severe, and in addition to the byproducts generated by uncontrolled substitution, various harmful impurities such as ligand self-polymers, chlorinated yttrium dimers, and low-valent yttrium colored species are easily generated, which cannot meet the core requirements of the ALD process for the thermal stability and self-limiting reaction of the precursor. Summary of the Invention

[0004] The purpose of this application is to provide a method for preparing yttrium precursors, so as to solve the technical problems of existing heterojunction yttrium precursor synthesis methods, such as difficulty in accurately controlling the substitution amount, poor reaction selectivity, low raw material conversion rate, and many by-products.

[0005] To achieve the above objectives, this application provides a method for preparing a yttrium precursor, wherein the yttrium precursor has the structure shown in general formula 1;

[0006]

General Formula 1

[0007] In the formula, n is an integer from 1 to 5, R and R 1 R 3 Each is independently selected from C1-C6 straight-chain alkyl groups and C3-C6 branched alkyl groups, R 2 Selected from hydrogen, C1-C6 straight-chain alkyl groups, and C3-C6 branched-chain alkyl groups;

[0008] The preparation method includes:

[0009] A compound having the following general formula 2 is reacted with a base to give a first intermediate compound having the following general formula 3;

[0010] The first intermediate compound was reacted with anhydrous yttrium halide to obtain a second intermediate compound having the following general formula 4;

[0011] The second intermediate compound is reacted with a compound having the following general formula 5 to obtain the yttrium precursor;

[0012]

General Formula 2

General Formula 3

[0013]

General Formula 4

[0014] In the general formula 3, M represents an alkali metal.

[0015] In one or more embodiments, the step of reacting a compound having general formula 2 with the base includes:

[0016] Under an inert atmosphere and with cooling and stirring, the compound having general formula 2 and the base are dispersed in a first organic solvent, then heated to a first reaction temperature to carry out the reaction. After the reaction is completed, the mixture is filtered and the filtrate is collected to obtain a solution of the first intermediate compound.

[0017] In one or more embodiments, the first organic solvent is tetrahydrofuran.

[0018] In one or more embodiments, the molar ratio of the compound having general formula 2 to the base is 1:(1~1.3).

[0019] In one or more embodiments, the cooling and stirring step involves a cooling temperature of -20°C to -10°C.

[0020] In one or more embodiments, the first reaction temperature is 18~30°C and the reaction time is 10~20h.

[0021] In one or more embodiments, the alkali is selected from one or more combinations of sodium hydride, potassium hydride, and n-butyllithium.

[0022] In one or more embodiments, the step of reacting the first intermediate compound with anhydrous yttrium halide includes:

[0023] Under an inert atmosphere, anhydrous yttrium halide was slowly added to the solution of the first intermediate compound at room temperature. The mixture was then heated to the second reaction temperature and refluxed. After the reaction was completed, the mixture was filtered and the filtrate was collected to obtain the solution of the second intermediate compound.

[0024] In one or more embodiments, the molar ratio of the anhydrous yttrium halide to the first intermediate compound is 1:(3~3.5).

[0025] In one or more embodiments, the second reaction temperature is 65~70°C and the reaction time is 5~8h.

[0026] In one or more embodiments, the anhydrous yttrium halide is selected from one or more combinations of yttrium trichloride, yttrium tribromide, and yttrium triiodide.

[0027] In one or more embodiments, the step of reacting the second intermediate compound with a compound having the following general formula 5 to obtain the yttrium precursor includes:

[0028] The solution of the second intermediate compound was distilled to remove the first organic solvent under an inert atmosphere. Then, the second intermediate compound was dispersed in a second organic solvent, and a compound having general formula 5 was added dropwise at room temperature, followed by stirring.

[0029] After the reaction is complete, the solution is filtered and the filtrate is collected. The filtrate is then purified to obtain the yttrium precursor.

[0030] In one or more embodiments, the second organic solvent is n-hexane.

[0031] In one or more embodiments, the molar ratio of the second intermediate compound to the compound having general formula 5 is 1:(1.1~1.3).

[0032] In one or more embodiments, the reaction temperature of the stirring reaction is 18~30°C, and the reaction time is 10~20h.

[0033] In one or more embodiments, the step of purifying the filtrate includes:

[0034] The filtrate was subjected to vacuum distillation under low vacuum conditions to remove the second organic solvent, and then subjected to rectification under high vacuum conditions. The fraction was collected to obtain the yttrium precursor.

[0035] The vacuum degree of the low vacuum condition is 100~1000Pa, the vacuum degree of the high vacuum condition is 5~20Pa, and the distillation temperature is 180~200℃.

[0036] In one or more embodiments, n=1 in general formula 1.

[0037] In one or more embodiments, R, R in general formula 1 1 R 3 Each is independently selected from methyl, ethyl, isopropyl, and tert-butyl.

[0038] In one or more embodiments, R in general formula 1 2 Selected from hydrogen, methyl, ethyl, isopropyl, and tert-butyl.

[0039] The advantages of this application, which differ from existing technologies, are:

[0040] This application employs a trisubstituted synthetic route, which allows for precise control of the substitution reaction process. This enables anhydrous yttrium halide to undergo a quantitative and complete trisubstituted reaction with a substituted cyclopentadienyl reagent, generating a single, pure, homo-trisubstituted yttrium cyclopentadienyl chloride intermediate Y(RCp)3. Subsequently, the intermediate undergoes a monoligand dissociation-exchange reaction with an amidine ligand to obtain the target disubstituted yttrium cyclopentadienyl chloride precursor. This approach completely eliminates the problem of uncontrolled degree of substitution due to mixed monosubstituted and multisubstituted products at the source of the reaction, avoiding the generation of byproducts such as monosubstituted yttrium chloride. The main reaction selectivity is close to 100%, ensuring the high purity of the intermediate from the source and improving the purity and yield of the target product.

[0041] The triceroxene yttrium intermediate Y(RCp)3 in the synthetic route of this application has excellent thermal stability. During the subsequent ligand exchange reaction and vacuum distillation purification process, it is not prone to side reactions such as self-reduction and ligand decomposition. This can ensure the integrity and stability of the coordination structure of the target heterojunction yttrium precursor, and the batch-to-batch products have excellent consistency in core ALD process performance such as thermal stability and saturated vapor pressure.

[0042] In this application, only a single Y(RCp)3 intermediate is generated throughout the entire reaction pathway, without complex byproducts such as monosubstituted chlorinated products or chlorinated bridged dimers. Subsequently, in the ligand dissociation-exchange reaction between the intermediate and the amidine ligand, only the target heteroligand product and the substituted cyclopentadiene small molecule byproduct are generated. The types of byproducts are extremely few, and they differ significantly from the target product in boiling point and polarity. No complicated purification process is required; efficient and deep separation can be achieved with just one vacuum distillation, with a separation efficiency that is more than 30% higher than that of existing disubstituted routes.

[0043] The reaction mechanism of this application is clear, and it has a wider tolerance to process parameters such as reaction temperature, stirring rate, and feed ratio. The reaction process is highly controllable, effectively avoiding the defects of existing bisubstituted routes that are highly sensitive to process fluctuations and have poor repeatability, and the process stability is greatly improved. Attached Figure Description

[0044] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0045] Figure 1 This is a schematic flowchart of one embodiment of the method for preparing the yttrium precursor of this application;

[0046] Figure 2 This is the hydrogen nuclear magnetic resonance spectrum of the yttrium precursor prepared in Example 1 of this application;

[0047] Figure 3 This is the hydrogen nuclear magnetic resonance spectrum of the yttrium precursor prepared in Example 2 of this application. Detailed Implementation

[0048] To enable those skilled in the art to better understand the technical solutions in this disclosure, the technical solutions in the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Based on the embodiments in this disclosure, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this disclosure.

[0049] Conventional homogeneous yttrium precursors cannot simultaneously meet the requirements of ALD / CVD processes, specifically as follows:

[0050] 1. O-coordinated β-diketone precursors are all-coordinated, typically tris(2,2,6,6-tetramethyl-3,5-heptadecyl)yttrium (Y(thd)3). Although these precursors have good thermal stability, they are solid-state complexes and require sublimation at 125°C to meet the requirements for ALD gas-phase transport. When ozone is used as an oxidant, the ALD process window is 250~375°C, but the film growth rate is only 0.23 Å / cycle, resulting in extremely low mass production efficiency. More importantly, the prepared films have extremely high impurity residues. Even when deposited at the upper limit of the ALD window of 350°C, the carbon and hydrogen impurity contents in the films are still as high as 1.0~1.4 at.% and 1.3~1.7 at.%, respectively, which cannot meet the stringent impurity requirements of advanced semiconductor processes.

[0051] 2. N-coordinated amidine-type precursors are typically tris(N,N'-diisopropylethamidinyl)yttrium. When water is used as the oxidant, this type of precursor can achieve a growth rate of 0.8 Å / cycle within a process window of 150~280℃, and the carbon and nitrogen impurities of the film can be reduced to below 0.5 at.%. However, it has fatal performance defects: First, the yttrium-oxygen ratio of the prepared Y2O3 film is close to 1:2, which deviates significantly from the ideal stoichiometric ratio of 2:3, directly deteriorating the dielectric properties; Second, the film is extremely hygroscopic and will quickly absorb moisture after being exposed to air. XPS characterization shows that there are a large number of γ-OH hydroxyl impurities, requiring additional in-situ capping layer deposition or high-temperature annealing processes to maintain electrical properties, which greatly increases the process complexity and mass production cost.

[0052] 3. Cyclopentadienyl (Cp) homopolymeric precursors, including Y(Cp)3, Y(MeCp)3, Y(EtCp)3, Y(iPrCp)3, etc., exhibit much higher reactivity with water than O-coordinated precursors. When water is used as the oxidant, the growth rate of Y2O3 thin films can reach 1.2~1.8 Å / cycle, which is 5~8 times that of the Y(thd)3 / ozone system. Among them, the carbon impurity content of the thin film prepared by Y(EtCp)3 is less than 0.5 at.%, and the ideal stoichiometric ratio of Y:O = 2:3 can be achieved. However, this type of homogeneous precursor has two major bottlenecks: First, the ALD process window is extremely narrow, with the Y(EtCp)3 system only at 250~285℃ and the Y(MeCp)3 system only at 250~300℃, which cannot adapt to the process fluctuations of mass production lines; Second, the precursor itself has poor thermal stability and is prone to self-decomposition at process temperatures, making it impossible to achieve stable self-limiting growth, which seriously limits its industrial application.

[0053] Therefore, the industry has begun to study hybrid yttrium precursors with high volatility, excellent thermal stability, wide ALD process window, low impurity residue, and ideal stoichiometry.

[0054] Currently, the preparation of disubstituted yttrium heterocyclopentadienylene precursors mostly adopts a synthetic route that directly disubstituted anhydrous yttrium trichloride with substituted cyclopentadienyl reagents. The core inherent defect is that the number of substitutions cannot be precisely controlled. During the reaction, monosubstituted and trisubstituted yttrium heterocyclopentadienylene byproducts are easily generated. The reaction selectivity of the target disubstituted yttrium heterocyclopentadienylene intermediate is extremely poor. The main reaction is generally incomplete and the conversion rate of the starting materials is low. This directly leads to the low yield of the subsequent target heterocyclopentadienylene precursor and the inability to stably obtain the target product in a room temperature liquid state.

[0055] Meanwhile, the reaction system of this synthetic route has violent side reactions. In addition to the byproducts caused by the uncontrolled degree of substitution, it is also easy to generate a variety of harmful impurities such as ligand self-polymers, chloro-bridged yttrium dimers, and low-valent yttrium colored species. These impurities will not only further reduce the reaction selectivity of the target product, but also cause the product color to exceed the standard. Among them, impurities such as low-valent yttrium species and chloro-bridged dimers will seriously damage the thermal stability of the precursor, causing the precursor to self-decompose at the process temperature, which completely fails to meet the core requirements of the ALD process for the thermal stability and self-limiting reaction of the precursor.

[0056] In addition, since the target heterogeneous precursor and impurities such as mono / trisubstituted byproducts and chlorobridged dimers have very small differences in boiling point, polarity and solubility, existing conventional purification methods such as distillation, recrystallization and vacuum sublimation cannot achieve effective deep separation. In order to meet the ultra-high purity requirements of semiconductor ALD precursors, a multi-step and cumbersome purification process is required, which directly leads to a significant decrease in the yield of the target product.

[0057] To address the aforementioned issues, the applicant has developed a novel method for preparing hybrid yttrium precursors. This method can efficiently prepare disubstituted cytocerium yttrium hybrid precursors and effectively avoid the preparation of monosubstituted and disubstituted cytocerium yttrium byproducts, thereby improving the selectivity of the target product, preventing byproduct formation, reducing separation difficulty, and significantly improving the yield and purity of the product, which can meet the requirements of advanced semiconductor processes.

[0058] Specifically, firstly, the hybrid yttrium precursor prepared in this application has the structure shown in General Formula 1, [General Formula 1] Y(η 5 -R n C5H 5-n )2(R 1 N=C(R 2 )NR 3 );

[0059] In the formula, n is an integer from 1 to 5, R and R 1 R 3 Each is independently selected from C1-C6 straight-chain alkyl groups and C3-C6 branched alkyl groups, R 2 It is selected from hydrogen, straight-chain alkyl groups of C1 to C6 and branched alkyl groups of C3 to C6.

[0060] Preferably, n can be 1, R, R 1 R 3 It can be methyl, ethyl, isopropyl, tert-butyl, R 2 It can be hydrogen, methyl, ethyl, isopropyl, or tert-butyl.

[0061] This yttrium precursor has a disubstituted cyclopentadienyl ligand and a monosubstituted amidine ligand. It is liquid at room temperature, exhibits excellent volatility and thermal stability, and has a wide ALD process window, which is significantly better than conventional homogeneous yttrium precursors.

[0062] The preparation method of this hybrid yttrium precursor is described in detail below. Please refer to [link / reference]. Figure 1 , Figure 1 This is a schematic flowchart of one embodiment of the method for preparing the yttrium precursor of this application.

[0063] like Figure 1 As shown, the preparation method includes:

[0064] S100. React the compound having general formula 2 with a base to obtain the first intermediate compound having general formula 3.

[0065]

General Formula 2

General Formula 3

[0066] Taking n=1 as an example, the compounds with general formula 2 are specifically: The first intermediate compound is specifically... .

[0067] In this embodiment, the substituted cyclopentadiene ligand is first deprotonated to prepare a more nucleophilic and thermodynamically stable metal salt, so that the metal salt can undergo a quantitative three-coordinate salt metathesis reaction with the yttrium salt.

[0068] In one embodiment, the base may be selected from one or more combinations of sodium hydride, potassium hydride, and n-butyllithium.

[0069] In one embodiment, the molar ratio of the compound having general formula 2 to the base can be 1:(1~1.3) to ensure sufficient reaction of the substituted cyclopentadiene ligand.

[0070] In one embodiment, the step of reacting a compound having general formula 2 with a base can be specifically described as follows:

[0071] Under an inert atmosphere and with cooling and stirring, the compound having general formula 2 and the base are dispersed in a first organic solvent, then heated to a first reaction temperature to carry out the reaction. After the reaction is completed, the mixture is filtered and the filtrate is collected to obtain a solution of the first intermediate compound.

[0072] In one embodiment, the compound having general formula 2 can be first dispersed in a first organic solvent, and then the base can be added and dispersed in the first organic solvent while cooling and stirring. In another embodiment, the base can be first dispersed in a first organic solvent, and then the compound having general formula 2 can be dispersed in the first organic solvent while cooling and stirring. Both methods can achieve the effect of this embodiment.

[0073] Based on the above scheme, by dispersing the cyclopentadiene ligand and the base under cooling and stirring conditions, the reaction rate can be effectively controlled to avoid the release of large amounts of hydrogen. Then, the temperature is raised to continue the reaction, ensuring that the cyclopentadiene ligand is completely deprotonated.

[0074] In one embodiment, the cooling temperature of the above-mentioned cooling stirring can be specifically -20°C to -10°C, and for example, it can be -15°C.

[0075] In one embodiment, the first reaction temperature can be 18~30℃, and the reaction time can be 10~20h to ensure complete reaction.

[0076] In one embodiment, the first organic solvent may be tetrahydrofuran.

[0077] Specifically, taking sodium hydride as the alkali, the reaction pathway of S100 can be defined as follows:

[0078] .

[0079] S200, the first intermediate compound is reacted with anhydrous yttrium halide to obtain a second intermediate compound having general formula 4.

[0080]

General Formula 4

[0081] Taking n=1 as an example, the second intermediate compound is specifically... .

[0082] In one embodiment, anhydrous yttrium halide may be selected from one or more combinations of yttrium trichloride, yttrium tribromide, and yttrium triiodide.

[0083] In this embodiment, a sodium salt ligand is used to perform a three-coordinate salt metathesis reaction with a yttrium salt to generate tricendolite-substituted yttrium with the highest stability.

[0084] Compared to existing technologies that directly generate the target disubstituted yttrium precursor, the synthetic route of this embodiment directly generates tricyclic yttrium. When the sodium salt ligand is in excess, the reaction will generate 100% tricyclic yttrium, fundamentally eliminating the presence of monosubstituted and disubstituted products. This allows subsequent substitution reactions to be directed to generate the disubstituted yttrium precursor, effectively avoiding the problem of difficulty in controlling the number of yttrium substitutions in traditional synthetic methods.

[0085] In one embodiment, the step of reacting the first intermediate compound with anhydrous yttrium halide may specifically include:

[0086] Under an inert atmosphere, anhydrous yttrium halide was slowly added to a solution of the first intermediate compound at room temperature. The mixture was then heated to a second reaction temperature and refluxed. After the reaction was completed, the mixture was filtered and the filtrate was collected to obtain a solution of the second intermediate compound.

[0087] Based on the above scheme, the reaction is initiated simultaneously when yttrium halide is added at room temperature to avoid internal heat accumulation. Then, the temperature is increased to accelerate the reaction rate and ensure complete reaction.

[0088] In one embodiment, the molar ratio of anhydrous yttrium halide to the first intermediate compound can be 1:(3~3.5) to ensure an excess of the first intermediate compound and to ensure that the substitution reaction fully synthesizes tricenzolide-substituted yttrium.

[0089] In one embodiment, the second reaction temperature can be 65~70°C and the reaction time can be 5~8h; preferably, the second reaction temperature can be 69°C to ensure distillation evaporation and condensation reflux, so that the reaction is complete.

[0090] Specifically, taking anhydrous yttrium halide as yttrium trichloride as an example, the reaction pathway of S200 can be specifically described as follows:

[0091] .

[0092] S300, the second intermediate compound and a compound having general formula 5 are reacted to obtain the yttrium precursor.

[0093]

Formula 5

[0094] In this embodiment, after preparing the trisubstituted yttrium cyclopentadienyl ligand precursor, a controlled ligand exchange reaction is performed to replace one cyclopentadienyl ligand with an amidine ligand, thereby obtaining the target product, the dicyclopentadienyl substituted yttrium heteroligand precursor.

[0095] Specifically, since the steric hindrance around the central metal is already large after the trisubstituted cyclopentadienyl yttrium precursor is replaced by an amidoyl ligand, the second amidoyl ligand cannot approach the metal center to react. Therefore, byproducts such as monosubstituted cyclopentadienyl or trisubstituted amidoyl yttrium precursors will not be generated. Furthermore, since the disubstituted cyclopentadienyl monosubstituted amidoyl yttrium hybrid precursor is the most thermodynamically stable hybrid product, the reaction will spontaneously stop at this step, thereby ensuring the directional generation of the target product and effectively suppressing the generation of byproducts.

[0096] In addition, in this embodiment, the reaction between the amidine group and Y(RCp)3 is directly used, which can effectively avoid the introduction of metal impurities and ensure the purity of the product compared to using amidine metal salts as raw materials.

[0097] In one embodiment, the step of reacting the second intermediate compound with a compound having general formula 5 may include:

[0098] The solution of the second intermediate compound was distilled to remove the first organic solvent under an inert atmosphere. Then the second intermediate compound was dispersed in the second organic solvent, and a compound having general formula 5 was added dropwise at room temperature while stirring the reaction.

[0099] After the reaction was completed, the solution was filtered and the filtrate was collected. The filtrate was then purified to obtain the yttrium precursor.

[0100] Specifically, in order to avoid the coordination inhibition effect of tetrahydrofuran, in this embodiment, the first organic solvent is first removed by distillation, and then the second intermediate compound is dissolved in the second organic solvent and reacted with the amidine ligand; the reaction is started simultaneously when the amidine ligand is added dropwise at room temperature to avoid internal heat accumulation, and then the mixture is stirred to ensure the reaction is complete.

[0101] In one embodiment, the second organic solvent may specifically be n-hexane.

[0102] In one embodiment, the reaction temperature of the stirring reaction can be 18~30℃, and the reaction time can be 10~20h to ensure a complete reaction.

[0103] In one embodiment, the molar ratio of the second intermediate compound to the compound having general formula 5 can be 1:(1.1~1.3).

[0104] In one embodiment, the step of purifying the filtrate can specifically be as follows:

[0105] The filtrate was subjected to vacuum distillation under low vacuum conditions to remove the second organic solvent, and then subjected to rectification under high vacuum conditions. The fraction was collected to obtain the yttrium precursor.

[0106] The vacuum level under low vacuum conditions is 100~1000Pa, the vacuum level under high vacuum conditions is 5~20Pa, and the distillation temperature is 180~200℃.

[0107] First, the hexane solvent is removed by low-vacuum distillation. Since the target product has a high boiling point, it will undergo thermal decomposition during distillation under normal pressure. Therefore, the target product is collected by distillation under high-vacuum conditions to ensure the integrity and purity of the product.

[0108] Specifically, the reaction path of S300 can be defined as follows:

[0109] .

[0110] Based on the preparation methods described above, a trisubstituted synthetic route is adopted, which allows for precise control of the substitution reaction process. This enables anhydrous yttrium halide to undergo a quantitative and complete trisubstituted reaction with the substituted cyclopentadienyl reagent, generating a single, pure, homo-trisubstituted yttricyclopentadienyl yttrium intermediate Y(RCp)3. This completely eliminates the problem of uncontrolled substitution degree due to mixed monosubstituted and multisubstituted reactions from the source, avoiding the generation of byproducts such as monosubstituted yttrium chloride. The main reaction selectivity is close to 100%, ensuring the high purity of the intermediate from the source. The tricyclic yttrium intermediate Y(RCp)3 exhibits excellent thermal stability and is not prone to side reactions such as self-reduction and ligand decomposition during subsequent ligand exchange reactions and vacuum distillation purification. This ensures the integrity and stability of the coordination structure of the target heterojunction yttrium precursor, and the batch-to-batch consistency of core ALD process performance such as thermal stability and saturated vapor pressure is excellent.

[0111] Simultaneously, only a single Y(RCp)3 intermediate is generated throughout the entire reaction pathway, without complex byproducts such as monosubstituted chlorinated derivatives or chlorinated bridged dimers. Subsequent intermediates react with the amidine ligand R... 1 N=C(R 2 )NR 3 A precise single-ligand dissociation-exchange reaction occurs, generating only the target heteroligand product and substituted cyclopentadiene small molecule byproducts. The types of byproducts are extremely few, and their boiling points and polarities differ significantly from those of the target product. No complicated purification process is required; efficient and deep separation can be achieved with just one vacuum distillation, with a separation efficiency that is more than 30% higher than that of existing bisubstituted routes.

[0112] In addition, the reaction mechanism is clear, and it has a wider tolerance to process parameters such as reaction temperature, stirring rate, and feed ratio. The reaction process is highly controllable, effectively avoiding the defects of existing bisubstituted routes that are highly sensitive to process fluctuations and have poor repeatability, thus greatly improving process stability.

[0113] The effects of the technical solution of this application are further described below with reference to specific embodiments.

[0114] Example 1:

[0115] A yttrium precursor has the following structure:

[0116] .

[0117] The preparation method of this yttrium precursor includes:

[0118] Step 1: Raw Material Pretreatment—Anhydrous yttrium trichloride (YCl3), isopropylcyclopentadiene (iPrCp), sodium hydride (NaH), and N,N'-diisopropylacetamidine (iPr-amd) are placed in a glove box (moisture and oxygen content ≤2ppm). Isopropylcyclopentadiene (iPrCp) and N,N'-diisopropylacetamidine (iPr-amd) are subjected to dehydration treatment using 4A molecular sieve drying. Sodium hydride (NaH) is thoroughly washed 5 times with anhydrous n-hexane. The purity of anhydrous yttrium trichloride is ≥99.99%, the purity of iPrCp is ≥99%, the purity of Me-amd is ≥99%, and the purity of sodium hydride (NaH) is 60%.

[0119] Step 2: Preparation of sodium ligand salt—Under an anhydrous and oxygen-free inert atmosphere, 162.28 g (1.5 mol) of pretreated iPrCp was dissolved in 800 ml of anhydrous tetrahydrofuran. After stirring evenly, 71.99 g (1.8 mol) of pretreated sodium hydride was slowly added. The addition temperature was controlled at -15℃. After the addition was completed, the reaction was stirred at -15℃ for 1 h, and then allowed to return to room temperature naturally for 12 h. The resulting reaction mixture was filtered to remove unreacted solid precipitate. The filtrate was collected to obtain Na[iPrCp] solution with a yield of 80%.

[0120] Step 3: Coordination reaction—Under an anhydrous and oxygen-free inert atmosphere, 73.22 g (375.00 mmol) of anhydrous YCl3 was slowly added to the prepared Na[iPrCp] solution at room temperature. After the addition was complete, the temperature was raised to 69 °C and stirred under reflux for 6 h. The resulting reaction mixture was filtered to remove the generated sodium chloride precipitate and the filtrate was collected.

[0121] Step 4: Coordination reaction—Under an anhydrous and oxygen-free inert atmosphere, the reaction filtrate obtained in Step 3 was placed in a vacuum distillation apparatus to remove the tetrahydrofuran solvent by distillation under vacuum conditions (vacuum degree of 100-1000 Pa) at a distillation temperature of 69℃; the obtained Y(iPrCp)3 solid was dissolved in 800 ml of anhydrous n-hexane, stirred evenly, and then 51.21 g (360.00 mmol) of pretreated iPr-amd ligand was slowly added dropwise at room temperature, and the reaction was stirred at room temperature for 12 h;

[0122] Step 5: Impurity Removal and Purification—The reaction mixture obtained in Step 4 is filtered to remove the solid precipitate, and the filtrate is collected. The filtrate is placed in a vacuum distillation apparatus, and the solvent is first removed by distillation under low vacuum conditions (vacuum degree of 100-1000 Pa) at a distillation temperature of 69℃. Then, it is purified by rectification under high vacuum conditions (vacuum degree of 5-20 Pa) at a rectification temperature of 180-200℃. The fraction is collected to obtain 116.81g of high-purity liquid yttrium precursor Y(iPrCp)2(iPr-amd).

[0123] Example 2:

[0124] A yttrium precursor has the following structure:

[0125] .

[0126] The preparation method of this yttrium precursor includes:

[0127] Step 1: Raw material pretreatment—Anhydrous yttrium trichloride (YCl3), ethylcyclopentadiene (EtCp), sodium hydride (NaH), and N,N'-diisopropylacetamidine (iPr-amd) were placed in a glove box (moisture and oxygen content ≤2ppm). Ethylcyclopentadiene (EtCp) and N,N'-diisopropylacetamidine (iPr-amd) were dehydrated separately using 4A molecular sieves for 12 hours. Sodium hydride (NaH) was thoroughly washed 5 times with anhydrous n-hexane. The purity of anhydrous yttrium trichloride was ≥99.99%, the purity of EtCp was ≥99%, the purity of iPr-amd was ≥99%, and the purity of sodium hydride (NaH) was 60%.

[0128] Step 2: Preparation of sodium ligand salt—Under an anhydrous and oxygen-free inert atmosphere, 141.24 g (1.5 mol) of pretreated EtCp was dissolved in 800 ml of anhydrous tetrahydrofuran. After stirring evenly, 46.80 g (1.95 mol) of pretreated sodium hydride was slowly added. The addition temperature was controlled at -15℃. After the addition was completed, the mixture was stirred at -15℃ for 1 h, and then allowed to return to room temperature naturally for 12 h. The resulting reaction mixture was filtered to remove unreacted solid precipitate. The filtrate was collected to obtain Na[EtCp] solution with a yield of 80%.

[0129] Step 3: Coordination reaction—Under an anhydrous and oxygen-free inert atmosphere, 71g (363.65mmol) of anhydrous YCl3 was slowly added to the prepared Na[EtCp] solution at room temperature. After the addition was complete, the temperature was raised to 69℃ and stirred under reflux for 6h. The resulting reaction mixture was filtered to remove the generated sodium chloride precipitate and the filtrate was collected.

[0130] Step 4: Coordination reaction—Under an anhydrous and oxygen-free inert atmosphere, the reaction filtrate obtained in Step 3 was placed in a vacuum distillation apparatus to remove the tetrahydrofuran solvent by distillation under vacuum conditions (vacuum degree of 100-1000 Pa) at a distillation temperature of 69℃; the obtained Y(EtCp)3 solid was dissolved in 800 ml of anhydrous n-hexane, stirred evenly, and then 53.80 g (378.19 mmol) of pretreated iPr-amd ligand was slowly added dropwise at room temperature, and the reaction was stirred at room temperature for 12 h;

[0131] Step 5: Impurity Removal and Purification—The reaction mixture obtained in Step 4 is filtered to remove the solid precipitate, and the filtrate is collected. The filtrate is placed in a vacuum distillation apparatus, and the solvent is first removed by distillation under low vacuum conditions (vacuum degree of 100-1000 Pa) at a distillation temperature of 69℃. Then, it is purified by rectification under high vacuum conditions (vacuum degree of 5-20 Pa) at a rectification temperature of 170-190℃. The fraction is collected to obtain 101.28g of high-purity liquid yttrium precursor Y(EtCp)2(iPr-amd).

[0132] Example 3:

[0133] A method for preparing a yttrium precursor is basically the same as that in Example 1, except that:

[0134] In step 2, 64.17 g (1.6 mol) of potassium hydride was used to replace sodium hydride, and the purity of potassium hydride was greater than 99%.

[0135] In step 3, 121.59 g (370.00 mmol) of anhydrous yttrium tribromide was used instead of anhydrous yttrium trichloride.

[0136] Example 4:

[0137] A method for preparing a yttrium precursor is basically the same as that in Example 1, except that:

[0138] In step 2, sodium hydride is replaced with 720 mL of a 2.5 mol / L n-butyllithium solution in hexane;

[0139] In step 3, 173.76 g (370.00 mmol) of anhydrous yttrium triiodide was used instead of anhydrous yttrium trichloride.

[0140] Example of effect 1:

[0141] The impurity content of the yttrium precursor prepared in Example 1 was detected by inductively coupled plasma mass spectrometry (ICP-MS). The results showed that the product purity was 99.9999%, the total metal impurity content was 0.43 ppm, the organic purity was >99%, which meets the requirements for precursors used in advanced semiconductor devices, and the reaction yield was 87.60%.

[0142] The yttrium precursor prepared in Example 1 was analyzed by ¹H NMR hydrogen nuclear magnetic resonance, and the results were obtained. Figure 2 , Figure 2 This is the hydrogen nuclear magnetic resonance spectrum of the yttrium precursor prepared in Example 1 of this application.

[0143] like Figure 2 As shown, the data is as follows:

[0144] 1HNMR(C6D6,25°C): δ0.99(d,12H, 3 J HH =8.0Hz, Y-NCH Me2 ),1.26(d,12H, 3 J HH =4.0Hz, Y-CpCH Me2 ),1.52(s,3H,Y-N2C Me ),2.92(m,2H,Y-NC H Me2), 3.30(m,2H,Y-CpC H Me2), 6.10-6.13(m,8H,Y- Cp CHMe2); conforms to the yttrium precursor characteristics of Example 1.

[0145] In summary, Example 1 successfully prepared the target product with high purity.

[0146] Example of effect 2:

[0147] The impurity content of the yttrium precursor prepared in Example 2 was detected by inductively coupled plasma mass spectrometry (ICP-MS). The results showed that the product purity was 99.9999%, the total metal impurity content was 0.33 ppm, the organic purity was >99%, which meets the requirements for precursors used in advanced semiconductor devices, and the reaction yield was 83.60%.

[0148] The yttrium precursor prepared in Example 2 was analyzed by ¹H NMR hydrogen nuclear magnetic resonance, and the results were obtained. Figure 3 , Figure 3 This is the hydrogen nuclear magnetic resonance spectrum of the yttrium precursor prepared in Example 2 of this application.

[0149] like Figure 2 As shown, the data is as follows:

[0150] 1HNMR(C6D6,25°C): δ0.97(d,12H, 3 J HH =4.0Hz, Y-NCH Me2 ),1.22(t,6H, 3 J HH=4.0Hz, Y-CpCH2 CH3 ),1.50(s,3H,Y-N2C Me ),2.54(q,4H, 3 J HH =4.0Hz, Y-Cp CH2 CH3), 3.29(m,2H,Y-NC H Me2), 6.04-6.12(m,6H,Y-Cp) Me It conforms to the yttrium precursor characteristics of Example 2.

[0151] In summary, Example 2 successfully prepared the target product with high purity.

[0152] It will be apparent to those skilled in the art that this disclosure is not limited to the details of the exemplary embodiments described above, and that this disclosure can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of this disclosure is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within this disclosure. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0153] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for preparing a yttrium precursor, characterized in that, The yttrium precursor has the structure shown in general formula 1; 【General Formula 1】Y(η 5 -R n C5H 5-n )2(R 1 N=C(R 2 )NR 3 ); In the formula, n is an integer from 1 to 5, R and R 1 R 3 Each is independently selected from C1-C6 straight-chain alkyl groups and C3-C6 branched alkyl groups, R 2 Selected from hydrogen, C1-C6 straight-chain alkyl groups, and C3-C6 branched-chain alkyl groups; The preparation method includes: A compound having the following general formula 2 is reacted with a base to give a first intermediate compound having the following general formula 3; The first intermediate compound was reacted with anhydrous yttrium halide to obtain a second intermediate compound having the following general formula 4; The second intermediate compound is reacted with a compound having the following general formula 5 to obtain the yttrium precursor; 【General Formula 2】R n C5H 6-n ;【General Formula 3】M[R n C5H 5-n ]; 【General Formula 4】Y(η 5 -R n C5H 5-n 3; [General Formula 5] ; In the general formula 3, M represents an alkali metal.

2. The preparation method according to claim 1, characterized in that, The step of reacting a compound having general formula 2 with the base includes: Under an inert atmosphere and with cooling and stirring, the compound having general formula 2 and the base are dispersed in a first organic solvent, then heated to a first reaction temperature to carry out the reaction. After the reaction is completed, the mixture is filtered and the filtrate is collected to obtain a solution of the first intermediate compound.

3. The preparation method according to claim 2, characterized in that, The first organic solvent is tetrahydrofuran; and / or, The molar ratio of the compound having general formula 2 to the base is 1:(1~1.3); and / or, In the cooling and stirring step, the cooling temperature is -20℃ to -10℃; and / or, The first reaction temperature is 18~30℃, and the reaction time is 10~20h; and / or, The alkali is selected from one or more combinations of sodium hydride, potassium hydride, and n-butyllithium.

4. The preparation method according to claim 2, characterized in that, The step of reacting the first intermediate compound with anhydrous yttrium halide includes: Under an inert atmosphere, anhydrous yttrium halide was slowly added to the solution of the first intermediate compound at room temperature. The mixture was then heated to the second reaction temperature and refluxed. After the reaction was completed, the mixture was filtered and the filtrate was collected to obtain the solution of the second intermediate compound.

5. The preparation method according to claim 4, characterized in that, The molar ratio of the anhydrous yttrium halide to the first intermediate compound is 1:(3~3.5); and / or, The second reaction temperature is 65~70℃, and the reaction time is 5~8h; and / or, The anhydrous yttrium halide is selected from one or more combinations of yttrium trichloride, yttrium tribromide, and yttrium triiodide.

6. The preparation method according to claim 4, characterized in that, The step of reacting the second intermediate compound with a compound having the following general formula 5 to obtain the yttrium precursor includes: The solution of the second intermediate compound was distilled to remove the first organic solvent under an inert atmosphere. Then, the second intermediate compound was dispersed in a second organic solvent, and a compound having general formula 5 was added dropwise at room temperature, followed by stirring. After the reaction is complete, the solution is filtered and the filtrate is collected. The filtrate is then purified to obtain the yttrium precursor.

7. The preparation method according to claim 6, characterized in that, The second organic solvent is n-hexane; and / or, The molar ratio of the second intermediate compound to the compound having general formula 5 is 1:(1.1~1.3).

8. The preparation method according to claim 6, characterized in that, The reaction temperature of the stirring reaction is 18~30℃, and the reaction time is 10~20h.

9. The preparation method according to claim 6, characterized in that, The step of purifying the filtrate includes: The filtrate was subjected to vacuum distillation under low vacuum conditions to remove the second organic solvent, and then subjected to rectification under high vacuum conditions. The fraction was collected to obtain the yttrium precursor. The vacuum degree of the low vacuum condition is 100~1000Pa, the vacuum degree of the high vacuum condition is 5~20Pa, and the distillation temperature is 180~200℃.

10. The preparation method according to claim 1, characterized in that, In general formula 1, n=1; and / or, In general formula 1, R, R 1 R 3 Each is independently selected from methyl, ethyl, isopropyl, tert-butyl; and / or, In general formula 1, R 2 Selected from hydrogen, methyl, ethyl, isopropyl, and tert-butyl.

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