Novel hafnium-containing compound, hafnium precursor composition containing the same, hafnium-containing thin film using the hafnium precursor composition, and method for producing the same.

Abstract

The present invention provides a novel hafnium compound, a precursor composition containing the hafnium compound, a hafnium-containing thin film produced using the precursor composition, and a method for producing the hafnium-containing thin film. [Solution] A hafnium compound represented by the following formula. (In the formula, R1 is independently an amino group, a silyl group, an alkoxy group, or a C2-C5 alkyl group. Also, R2 and R3 are independently an amino group, a silyl group, an alkoxy group, or a C1-C5 alkyl group.) JPEG2026098078000009.jpg89159

Description

Technical Field

[0001] The present invention relates to a novel hafnium compound, a precursor composition containing the hafnium compound, a hafnium-containing thin film produced using the precursor composition, and a method for producing the hafnium-containing thin film.

Background Art

[0002] Capacitance is proportional to the dielectric constant of a dielectric and the area of a capacitor, and inversely proportional to the thickness of the dielectric. In order to increase capacitance, it is necessary to either structurally increase the area of the capacitor or decrease the thickness of the dielectric, or to develop a material with a high dielectric constant. However, when using a cylindrical capacitor to increase the area, not only is a high-level etching technique required, but a tilting phenomenon occurs when designing to a height above a certain level. In addition, as the device scale is gradually miniaturized, there is a problem that a high leakage current is generated due to the tunneling effect. Therefore, since there is a limit to structurally increasing capacitance, the development of precursor materials and thin film deposition for dielectrics with a high dielectric constant is required.

[0003] Recently, the development of oxide thin films based on Group 4 metals such as hafnium or zirconium has been actively carried out. This is widely applied as a high dielectric constant thin film material due to its relatively wide bandgap energy, Si integration, and high compatibility. Hafnium oxide film or zirconium oxide film has a high dielectric constant depending on the crystal structure of the thin film. Recently, a method of slightly doping hafnium / zirconium composite oxide film (HfZrO2), hafnium oxide film or zirconium oxide film with aluminum (Al), yttrium (Y), lanthanum (La), etc. to enhance the structural and electrical properties of the thin film has also been applied.

[0004] For example, Korean Published Patent No. 10-2018-0132568 describes a technique for forming a thin film containing an organo-group IV compound using a hafnium complex containing a cyclopentadienyl group as a precursor. The hafnium compound used in the aforementioned prior art improves deposition efficiency by containing a cyclopentadienyl group, but this is for forming composite metal thin films with metal atoms such as aluminum, gallium, and germanium. There are limitations to improving the deposition rate, uniformity, flatness, and purity of the thin film, and the development of an improved precursor is needed. [Overview of the project] [Problems that the invention aims to solve]

[0005] The present invention relates to a high dielectric precursor technology devised in view of the above-described prior art, and aims to provide a novel hafnium compound that can be used as a precursor for a high dielectric constant thin film containing hafnium, and a hafnium precursor composition containing the hafnium compound.

[0006] Furthermore, the present invention aims to provide a high dielectric constant thin film using the hafnium-containing precursor composition and a method for producing the same. [Means for solving the problem]

[0007] The hafnium compound of the present invention, which achieves the above objective, can be used as a precursor for forming a hafnium-containing thin film and is characterized by being represented by the following chemical formula 1. [ka]

[0008] In the formula, R1 is independently an amino group, a silyl group, an alkoxy group, or a C2-C5 alkyl group. Also, R2 and R3 are independently an amino group, a silyl group, an alkoxy group, or a C1-C5 alkyl group.

[0009] In particular, the chemical formula 1 is represented by one of the following compounds. [ka]

[0010] Since the hafnium compound contains a methyl group and R1 on the cyclopentadienyl group, it exhibits a steric hindrance effect of the cyclopentadienyl group, which suppresses intermolecular and intramolecular interactions of the hafnium compound, resulting in higher thermal stability. This increases the chemisorption rate during the thin film formation process, improving the thin film formation rate and uniformity of the thin film, and enabling the formation of a higher quality hafnium-containing thin film compared to conventional hafnium compounds containing cyclopentadienyl groups.

[0011] Furthermore, the hafnium-containing precursor composition of the present invention may contain the hafnium compound.

[0012] Furthermore, the thin film according to the present invention can be produced using the hafnium-containing compound or hafnium-containing precursor composition.

[0013] Furthermore, the method for producing a thin film according to the present invention may be a method using the hafnium-containing compound or hafnium-containing precursor composition.

[0014] Furthermore, the thin film manufacturing method according to the present invention can be manufactured using the mixture of hafnium compounds.

[0015] Furthermore, the hafnium-containing thin film and the method for producing the thin film include the step of depositing the hafnium-containing precursor composition or the hafnium compound onto a substrate, in which case the deposition may be carried out by any one of the following methods: plasma-enhanced chemical vapor deposition, thermochemical vapor deposition, plasma-enhanced atomic layer deposition, and thermal atomic layer deposition.

[0016] Furthermore, the method for manufacturing the thin film may include a first step of cleaning and surface-treating a substrate; a second step of placing the substrate in a chamber and heating the substrate; a third step of forming a monolayer on the substrate using the hafnium-containing compound or the hafnium-containing precursor composition; a fourth step of supplying reactants to form a hafnium-containing thin film; and a fifth step of purging unreacted material.

[0017] The process may further include the step of depositing a metal precursor different from the hafnium-containing compound or the hafnium-containing precursor composition onto a substrate.

[0018] Furthermore, the heating temperature of the substrate can be between 100 and 800°C.

[0019] Furthermore, the reactant may be any of O2, O3, H2O, NO, NO2, N2O, H2O2, H2, NH3, alkylamine, hydrazine derivative, SiH4, Si2H6, BH3, B2H6, amine-borane complex, GeH4, PH3, or a mixture of these gases. [Effects of the Invention]

[0020] The hafnium-containing precursor composition according to the present invention is liquid at room temperature, has excellent volatility and thermal stability, and is very effective for producing a high-purity hafnium-containing thin film.

[0021] In addition, due to its high thermal stability, it is possible to achieve a wide range of atomic layer deposition process temperatures and achieve the effect of producing a highly pure crystalline hafnium-containing thin film.

Brief Description of the Drawings

[0022] [Figure 1] 1H-NMR analysis results of (ethylmethylcyclopentadienyl)(trisdimethylamino)hafnium produced in Example 1. [Figure 2] Results of measuring the vapor pressure of (ethylmethylcyclopentadienyl)(trisdimethylamino)hafnium produced in Example 1. [Figure 3] Thermogravimetric analysis (TGA) results of (ethylmethylcyclopentadienyl)(trisdimethylamino)hafnium produced in Example 1. [Figure 4] Graph showing the range of atomic layer deposition process temperature (ALD Window) of the (ethylmethylcyclopentadienyl)(trisdimethylamino)hafnium thin film produced in Example 2 and the (cyclopentadienyl)(trisdimethylamino)hafnium thin film produced in Comparative Example 1. [Figure 5] X-ray photoelectron spectroscopy (XPS) image of the (ethylmethylcyclopentadienyl)(trisdimethylamino)hafnium thin film produced in Example 2 and the (cyclopentadienyl)(trisdimethylamino)hafnium-containing thin film produced in Comparative Example 1. <映画= [Figure 6] Scanning electron microscope (SEM) image showing the thickness uniformity of the (ethylmethylcyclopentadienyl)(trisdimethylamino)hafnium thin film produced in Example 2. [Figure 7]These are scanning probe microscope (AFM) images of the (ethylmethylcyclopentadienyl)(trisdimethylamino)hafnium thin film produced in Example 2 and the (cyclopentadienyl)(trisdimethylamino)hafnium-containing thin film produced in Comparative Example 1. [Modes for carrying out the invention]

[0023] The present invention will now be described in more detail. The terms and words used herein and in the claims shall not be construed to be limited to their ordinary or dictionary meanings, but rather to be interpreted in a sense and concept consistent with the technical idea of ​​the present invention, in accordance with the principle that inventors may appropriately define the concepts of terms in order to best describe their invention.

[0024] The hafnium-containing precursor according to the present invention is a hafnium compound represented by the following chemical formula 1, or a precursor composition containing a hafnium compound, which is liquid at room temperature and has excellent volatility and thermal stability, making it very effective for producing high-purity hafnium-containing thin films.

[0025] Furthermore, its high thermal stability enables a wide range of atomic layer deposition process temperatures, achieving the effect of producing high-purity crystalline hafnium-containing thin films. [ka]

[0026] In the formula, R1 is independently an amino group, a silyl group, an alkoxy group, or a C2-C5 alkyl group. Also, R2 and R3 are independently an amino group, a silyl group, an alkoxy group, or a C1-C5 alkyl group.

[0027] The precursor containing the aforementioned hafnium-containing compound is liquid at room temperature and possesses high volatility and thermal stability, making it a very useful precursor for forming hafnium-containing thin films.

[0028] In this specification, the term "alkyl" means a linear or branched saturated hydrocarbon group, including, for example, methyl, ethyl, propyl, isobutyl, pentyl, or butyl. Furthermore, C1-C5 alkyl means an alkyl group having 1 to 5 carbon atoms, and when a C1-C5 alkyl is substituted, the carbon number of the substituted product is not included.

[0029] Specific examples of the chemical formula 1 for forming a hafnium-containing thin film include, but are not limited to, the following chemical structures. [ka]

[0030] The hafnium compound can be used as a hafnium-containing precursor on its own, or it can be used in the form of a hafnium-containing precursor composition mixed with a solvent. In the case of a precursor composition, the composition can be formed by containing 0.1 to 99.9% by weight of the solvent relative to the total composition. The solvent can be any solvent that can dissolve the hafnium, but preferably saturated or unsaturated hydrocarbons, cyclic ethers, acyclic ethers, esters, alcohols, cyclic amines, acyclic amines, cyclic sulfides, acyclic sulfides, phosphines, β-diketones, or β-ketoesters.

[0031] The hafnium-containing thin film according to the present invention can be manufactured by conventional methods, including, for example, metal-organic chemical vapor deposition (MOCVD), atomic layer deposition (ALD), low-pressure vapor deposition (LPCVD), plasma-enhanced vapor deposition (PECVD), or plasma-enhanced atomic layer deposition (PEALD).

[0032] Furthermore, a composite metal-containing thin film containing hafnium can also be formed by further including the step of depositing a metal-containing precursor different from the hafnium compound or hafnium-containing precursor composition onto a substrate. In this case, a hafnium-containing thin film partially containing a composite metal-containing thin film can also be formed by depositing at least a portion of the metal-containing precursor onto one or more substrates.

[0033] As the metal-containing precursor for forming the composite metal-containing thin film, a precursor containing one or more metal atoms from among Zr, Ti, Sc, Y, La, Ac, V, Nb, Ta, Al, Ga, In, Si, Ge, Sn, and Pb can be used.

[0034] The hafnium-containing thin film formed in this way contains HfO2 and HfZrO x , HfTiO x , and HfAO x A includes one or more of the following, where A may be one or more of the following: Sc, Y, La, Ac, V, Nb, Ta, Al, Ga, In, Si, Ge, Sn, Pb.

[0035] Furthermore, as the substrate for forming the hafnium-containing thin film, titanium nitride, titanium, boron nitride, molybdenum sulfide, molybdenum, zinc oxide, tungsten, copper, aluminum oxide, tantalum nitride, niobium nitride, silicon, silicon oxide, titanium oxide, strontium oxide, or a combination thereof can be used.

[0036] In this case, the deposition temperature of the substrate is preferably 100 to 800°C, and as the reaction gas, one of the following or a mixture thereof can be used: O2, O3, H2O, NO, NO2, N2O, H2O2, H2, NH3, alkylamine, hydrazine derivative, SiH4, Si2H6, BH3, B2H6, amine borane complex, GeH4, PH3.

[0037] The present invention will be described in more detail below with reference to examples and comparative examples.

[0038] [Example 1] In a flame-dried 2,000 ml Schlenk flask, 1,000 ml of n-hexane and 177.4 g (0.5 mol) of tetrakis(dimethylamino)hafnium were added and mixed under a nitrogen atmosphere. The mixture was then cooled to 0°C, and 59.5 g (0.55 mol) of monoethylmethylcyclopentadiene was slowly added. After the addition was complete, the reaction mixture was gradually heated to room temperature and stirred for a further 16 hours. After the reaction was complete, the solvent was completely removed by reducing the pressure. To increase the purity, distillation was performed under reduced pressure (56°C / 0.11 Torr) to obtain 137.8 g (yield, 65%) of the title compound as a yellow liquid. 1 The results of the 1H-NMR analysis are shown in Figure 1, confirming that the compound is (ethylmethylcyclopentadienyl)(trisdimethylamino)hafnium. The results of the vapor pressure measurement of the hafnium compound are shown in Figure 2, and the results of the thermogravimetric analysis (TGA) are shown in Figure 3.

[0039] [Example 2] A hafnium-containing thin film was formed by depositing the compound from Example 1 as a hafnium precursor in vapor form (precursor canister temperature 80°C) onto a silicon substrate at a substrate temperature of 300°C to 370°C (Example 2-1: substrate temperature 300°C, Example 2-2: substrate temperature 340°C, Example 2-3: substrate temperature 370°C) using atomic layer deposition. Ozone (O3) was used as the reaction gas, and argon (Ar), an inert gas, was used for purging. The specific hafnium-containing thin film deposition method is shown in Table 1 below.

[0040] [Comparative Example 1] As a comparative compound, [(cyclopentadienyl)(trisdimethylamino)hafnium] was deposited onto a silicon substrate to form a hafnium-containing thin film. Table 1 below shows the specific hafnium-containing thin film deposition method for Comparative Example 1.

[0041] [Table 1]

[0042] The hafnium-containing thin films deposited in Examples 2-1 to 2-3 show a higher deposition rate compared to the hafnium-containing thin film deposited in Comparative Example 1.

[0043] Furthermore, in Figure 4, thermal decomposition occurs from around 340°C during the hafnium-containing deposition process using the compound of Comparative Example 1. However, the hafnium-containing thin films deposited in Examples 2-1 to 2-3 exhibit a stable atomic layer deposition process temperature range (ALD Window) of 370°C or higher. This indicates that the compound of Example 1 exhibits significantly higher thermal stability compared to the compound of Comparative Example 1.

[0044] Furthermore, Figure 5 shows that the hafnium-containing thin films deposited in Examples 2-1 to 2-3 were high-purity thin films with almost no carbon content compared to Comparative Example 1.

[0045] Furthermore, Figure 6 shows that the hafnium-containing thin films deposited in Examples 2-3 exhibit excellent thickness uniformity.

[0046] Furthermore, Figure 7 shows that the hafnium thin films deposited in Examples 2-1 to 2-3 are denser and have a flatter morphology compared to the hafnium-containing thin film deposited in Comparative Example 1.

[0047] Although the present invention has been described with reference to preferred embodiments as described above, it is not limited to these embodiments, and various modifications and alterations are possible by persons with ordinary skill in the art to which the invention pertains without departing from the spirit of the invention. Such modifications and alterations should also be considered to fall within the scope of the present invention and the appended claims.

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