Precursor for forming high-purity group 4 transition metal-containing thin films and method for producing the same.

Abstract

The present invention relates to a precursor for forming a high-purity group IV transition metal-containing thin film and a method for producing the same, wherein the production method includes a step of heat-treating a group IV transition metal compound at a heat treatment temperature, and the precursor for forming a high-purity group IV transition metal-containing thin film exhibits the effect of reducing the impurity content and enabling the production of a high-quality group IV transition metal-containing thin film.

Description

Technical Field

[0001] The present invention relates to a precursor for forming a high-purity Group 4 transition metal-containing thin film and a method for producing the same, and to a precursor for forming a high-purity Group 4 transition metal-containing thin film and a method for producing the same that can increase the purity by reducing impurities in the precursor and form a high-quality thin film.

Background Art

[0002] A thin film containing a Group 4 transition metal can provide a high dielectric constant thin film with a high aspect ratio and low leakage current when applied to a semiconductor. Such a Group 4 transition metal-containing thin film is formed by depositing a precursor on a substrate. At this time, since the quality and electrical characteristics of the thin film vary depending on the type of precursor used, various organometallic compounds are used as precursors.

[0003] Among these compounds, Group 4 transition metal compounds containing a cyclopentadienyl ligand such as cyclopentadienyltris(dimethylamido)zirconium (CpZr(NMe2)3) and cyclopentadienyltris(dimethylamido)hafnium (CpHf(NMe2)3) are widely used as precursors capable of forming high-quality thin films.

[0004] In addition, many examples have been proposed in which the chemical structure of the compound containing the cyclopentadienyl ligand is modified and applied as a precursor (Korean Patent Publication Nos. 10-2008-0101040, 10-2014-0121761, and 10-2021-0114890, Korean Registered Patent No. 10-1838617).

[0005] The compound containing the cyclopentadienyl ligand, even without altering its chemical structure, can form a high-dielectric-constant thin film with excellent step coverage characteristics when deposited by processes such as atomic layer deposition (ALD) using CpHf(NMe2)3 as a precursor (Korean Patent No. 10-0852234). Therefore, hafnium compounds containing cyclopentadienyl ligand can be effective as precursors.

[0006] However, when using hafnium compounds containing cyclopentadienyl ligands as precursors, impurities, particularly metallic impurities, are present in the precursor, and these impurities affect the electrical properties of the semiconductor device. To resolve this, it is necessary to control the impurity content at the ppb level.

[0007] To control impurities in the precursor and obtain a high-purity precursor, one method is to purify (distill) the obtained raw material precursor to increase its purity. However, for some impurities, the volatility is similar to that of the precursor, so there are limits to how much the impurity content can be reduced through purification (distillation). Attempts to increase purity through sublimation and recrystallization also exist, but there are limits to how much the impurity content can be reduced below the target value.

[0008] If the precursor to be obtained has high thermal stability, a method can be considered to increase its purity by utilizing the difference in thermal stability between the impurities and the precursor. After synthesis, a high-purity precursor can be obtained by distillation from a mixture of the impurities and the precursor that have been decomposed or polymerized by purification.

[0009] In particular, when the raw materials used in the synthesis of a compound are of low purity, this problem becomes more serious, and a separate process to control impurities at the raw material selection stage may be required. [Overview of the Initiative] [Problems that the invention aims to solve]

[0010] The present invention was devised in consideration of the above-mentioned prior art, and aims to provide a method that can effectively reduce impurities in a Group IV transition metal compound used as a precursor for forming a Group IV transition metal thin film, in order to increase the purity of the precursor.

[0011] Specifically, the objective is to provide a manufacturing method that enables the production of high-purity group IV transition metal thin film precursors by introducing a heat treatment process during the precursor manufacturing process to decompose impurities.

[0012] Furthermore, the objective is to provide a precursor for forming a high-purity group IV transition metal-containing thin film obtained by applying a process to reduce such impurities. [Means for solving the problem]

[0013] The present invention, which provides a method for producing a high-purity group IV transition metal-containing thin film precursor to solve the above problems, is characterized by including a step of heat-treating a group IV transition metal compound at a heat treatment temperature.

[0014] In this case, the heat treatment temperature is 80 to 240°C, preferably 100 to 210°C, and more preferably 120 to 180°C, and the heat treatment can be performed at the heat treatment temperature for 0.01 to 48 hours, preferably 0.01 to 24 hours, and more preferably 0.01 to 12 hours.

[0015] Furthermore, the heat treatment step can be performed after raising the temperature from room temperature to the heat treatment temperature at a heating rate of 0.1 to 10°C / minute.

[0016] Furthermore, the procedure may include purifying the group 4 transition metal compound at least once before or after heat treatment.

[0017] Furthermore, the purification step can be carried out by distilling the Group IV transition metal compound under reduced pressure.

[0018] Further, the precursor for forming the high-purity Group 4 transition metal-containing thin film may have a niobium (Nb) content reduced by 40% or more compared to the Group 4 transition metal compound.

[0019] Also, the heat treatment step can be carried out by i) heat treating within the container on which the Group 4 transition metal compound is supported, ii) heat treating the Group 4 transition metal compound in the transfer section where it is transferred from the container to another container, or iii) heat treating the Group 4 transition metal compound within the container on which it is supported and in the transfer section where it is transferred from the container to another container.

[0020] The precursor for forming the high-purity Group 4 transition metal-containing thin film of the present invention is manufactured by the above manufacturing method, and includes the step of heat treating the Group 4 transition metal compound at the heat treatment temperature, and is characterized in that the niobium (Nb) content is reduced by 40% or more compared to the Group 4 transition metal compound.

Advantages of the Invention

[0021] The manufacturing method of the precursor for forming the high-purity Group 4 transition metal-containing thin film according to the present invention shows the effect that impurities of the precursor can be effectively reduced in order to purify the Group 4 transition metal compound used as the precursor for forming the Group 4 transition metal thin film.

[0022] In particular, by introducing a heat treatment step in the manufacturing process of the precursor to decompose impurities, a precursor for forming a high-purity Group 4 transition metal thin film can be obtained.

[0023] Also, a high-quality Group 4 transition metal-containing thin film can be formed through such a precursor for forming a high-purity Group 4 transition metal-containing thin film.

Brief Description of the Drawings

[0024] [Figure 1] 1H-NMR measurement results of CpHf(DMA)3 manufactured by the synthesis example. [Figure 2] TGA analysis results of CpHf(DMA)3. [Figure 3] This is the DSC analysis result for CpHf(DMA)3. [Figure 4] This is the ICP-MS analysis result for CpHf(DMA)3. [Figure 5] This shows the 1H-NMR measurement results of CpHf(DMA)3 prepared according to Experimental Example 1-1. [Figure 6] These are the 1H-NMR measurement results of the initial, main, and final distillates and residues of a separation experiment of a mixture of CpHf(DMA)3 and Nb(DMA)5. [Figure 7] This is the 1H-NMR measurement result evaluating the heat treatment effect of a mixture of CpHf(DMA)3 and Nb(DMA)5. [Figure 8] This is the 1H-NMR measurement result evaluating the heat treatment effect of a mixture of CpZr(DMA)3 and Nb(DMA)5. [Figure 9] This shows the TGA analysis results for CpHf(DMA)3 and Nb(DMA)5 synthesized by Synthesis Example 1. [Figure 10] These are photographs of sample 17(a), which underwent heat treatment in Example 1-7, and sample 18(b), which did not undergo heat treatment. [Figure 11] These are photographs showing the color changes at each stage of sample 19 and sample 20 in Example 1-8. [Figure 12] These are photographs showing the color changes of sample 21 at each stage in Examples 1-9. [Modes for carrying out the invention]

[0025] The present invention will now be described in more detail. Terms and words used herein and in the claims should not be interpreted in a manner limited to their ordinary or lexicographical meanings, but rather in a manner 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.

[0026] The present invention provides a method for producing a high-purity Group IV transition metal-containing thin film formation precursor, which reduces impurities in the Group IV transition metal compound used as the precursor. Specifically, the method includes a step of heat-treating the Group IV transition compound at a heat treatment temperature.

[0027] The aforementioned group 4 transition metal compound is a precursor typically used for forming group 4 transition metal-containing thin films, and is an organometallic compound CpM(NMe2)3 containing a cyclopentanienyl ligand, or a compound with a different functional group than the aforementioned CpM(NMe2)3 (R 1 ) n It contains CpM(NR2R3)3 (where M is Ti, Hf or Zr, and R 1 R may be the same or different from each other, and is a hydrogen atom or a C1-C4 alkyl group. 2 , R 3 (Each of these is an alkyl group independently of C1-C4.)

[0028] While such cyclopentadienyl ligands containing group IV transition metal compounds can be useful as precursors for thin film formation, the electrical properties of the thin film are affected by impurities contained in the compound itself, particularly trace amounts of impurities remaining during the synthesis process.

[0029] The manufacturing method of the present invention is technically characterized by applying a step of heat treatment of the Group IV transition metal compound at a heat treatment temperature in order to solve the aforementioned problems.

[0030] In this case, the heat treatment temperature may be 80 to 240°C, preferably 100 to 210°C, and more preferably 120 to 180°C. Furthermore, the heat treatment can be performed at the heat treatment temperature for 0.01 to 48 hours, preferably 0.01 to 24 hours, and more preferably 0.01 to 12 hours.

[0031] Here, the heat treatment is a process introduced to reduce impurities contained in the object to be heat-treated, and the heat treatment temperature can be understood as the temperature of the object to be heat-treated.

[0032] If the heat treatment temperature is too low and falls outside the above range, it will not be possible to reduce the impurity content below the target value. If it is too high, problems may arise such as a decrease in production efficiency due to vaporization of the compound or thermal decomposition of the precursor compound itself. Also, if the heat treatment time is too short, it will not be possible to sufficiently reduce the impurity content. If the heat treatment time is too long, the process time will be prolonged, which may lead to a decrease in production efficiency.

[0033] Furthermore, it is preferable that the heat treatment step be performed after raising the temperature from room temperature to the heat treatment temperature at a heating rate of 0.1 to 10°C / minute. The heating rate is also an important process condition in heat treatment, but in a normal heat treatment process, the temperature is raised at a rate of 10°C / minute or less. If the heating rate is too slow, the overall heat treatment process time becomes longer and the process efficiency decreases, so it is preferable to apply the above range of heating rates when performing the heat treatment.

[0034] Furthermore, the heat treatment step can be performed in the following ways: i) heat treatment in a container on which the group IV transition metal compound is supported; ii) heat treatment of the group IV transition metal compound in a transfer section where it is moved from one container to another; or iii) heat treatment of the group IV transition metal compound both in the container on which the group IV transition metal compound is supported and in a transfer section where it is moved from one container to another.

[0035] For example, the group IV transition metal compound can be supported (stored) in a first container (storage container or reaction container) and may also undergo a process of moving from the first container to another second container (storage container or reaction container). Method i) is a method of heat-treating the group IV transition metal compound by heating the inside of the first container; Method ii) is a method in which the group IV transition metal compound supported in the first container moves to the second container, and the movement section is heated to a high temperature (heat treatment temperature), and the group IV transition metal compound is heat-treated while moving through the movement section; Method iii) is a method in which the group IV transition metal compound is heat-treated in the first container, and the movement section in which the group IV transition metal compound moves to the second container is also heated, and the movement section is also heat-treated. In this case, the container may be a storage container for storing precursors, a reaction container for carrying out a reaction, or a purification container, but is not limited to these.

[0036] Furthermore, it is preferable to perform a purification step along with the heat treatment step of the group IV transition metal compound. The purification step can be performed before or after the heat treatment of the group IV transition metal compound, or it may be performed before the heat treatment and again after the heat treatment. The purification step may be repeated one or more times. The purity of the group IV transition metal-containing thin film formation precursor obtained by performing such a purification step can be increased.

[0037] Furthermore, the purification step can be carried out by using a method of vacuum distillation to remove the group IV transition metal compound during the purification stage.

[0038] By performing heat treatment in this manner, and carrying out the heat treatment and purification process, the high-purity Group IV transition metal-containing thin film formation precursor of the present invention can have a niobium (Nb) content of 50 ppb or less, preferably 40 ppb or less, and more preferably 30 ppb or less.

[0039] When niobium is present as an impurity, it can react with the amine group of the hafnium compound to form a byproduct, which reduces the deposition efficiency of the Group IV transition metal compound as a precursor. Since such niobium has a similar volatility to the Group IV transition metal-containing thin film precursor, there are limitations to reducing its content through general purification methods such as distillation. Therefore, the application of a novel reduction technique like that of the present invention is preferable.

[0040] The high-purity group IV transition metal-containing thin film formation precursor produced by the present invention may have a niobium (Nb) content reduced by 40% or more compared to the aforementioned group IV transition metal compound. This value can be used as an indicator to confirm the purity of the group IV transition metal-containing thin film formation precursor.

[0041] To confirm the effects of the manufacturing method of the present invention, a precursor for forming a Group IV transition metal-containing thin film was manufactured as follows, and its physical properties were evaluated.

[0042] Synthesis Example: Synthesis of (cyclopentadienyltrisdimethylamino)hafnium (CpHf(DMA)3) Li-DMA was prepared by slowly adding 138.47 ml (345.6 mmol) of n-BuLi hexane solution (2.5 M) to 19.48 g (432.1 mmol) of dimethylamine in 1 L of hexane in a flask at -20°C. The solution was stirred at -20°C for 30 minutes, then the temperature was raised to 60°C and stirred for a further 5 hours.

[0043] Using a solid adding tube, 27.00 g (84.3 mmol) of hafnium chloride was added at -20°C. The mixture was stirred at -20°C for 30 minutes, then the temperature was raised to 40°C and stirred for a further 4 hours.

[0044] The mixture was cooled to room temperature, filtered, and then the solvent and volatile substances were evaporated under vacuum to obtain a deep yellow liquid. The obtained liquid was distilled at 60°C and 20 mTorr to obtain a clear liquid. The yield was 21.4 g (67.5%).

[0045] For the resulting liquid compound 1 The measurements were performed using 1H-NMR (Bruker AV400MHz HD (solvent: benzene-d6)). The results are shown in Figure 1. 1 H NMR(C6D6, 25℃): 2.95(s, 18H), 6.03(s, 5H)

[0046] Furthermore, the obtained pale orange liquid was subjected to a TGA measurement (using an SDT Q600 from TA instrum) while increasing the temperature by 10°C / min under an atmosphere of nitrogen flowing at 200 ml / min, and the percentage of weight loss due to temperature change was measured. The results are shown in Figure 2. As can be seen from the results in Figure 2, 0.5% residual mass remains during the TGA analysis measured at 10°C / min. These results suggest that the generated compound exhibits a volatility and thermal stability suitable for the vapor deposition process.

[0047] Furthermore, the heat flow (HSC) was measured using DSC (DSC25, TA Instrument Co., Ltd.) while the resulting pale orange liquid was heated at 10°C / min under an atmosphere of nitrogen flowing at 50 ml / min. As shown in Figure 3, the thermal decomposition temperature was 342°C during the DSC analysis measured at 10°C / min, confirming good thermal stability.

[0048] Furthermore, the obtained pale orange liquid was measured using an inductively coupled plasma mass spectrometer (ICP-MS) (Nexion 300s, Perkinelmer). The results are shown in Figure 4.

[0049] Experimental Example 1. Preliminary experiment to confirm the niobium reduction effect of introducing heat treatment. To confirm the niobium reduction effect achieved by applying the heat treatment process, preliminary experiments were conducted using the experimental examples 1-1 to 1-6 below.

[0050] For this reason, the by-product generated by the Nb impurity was assumed to be Nb(DMA)5. Furthermore, a CpHf(DMA)3 mixture containing Nb(DMA)5 was produced by applying the same method as in the above synthesis example, except that a certain proportion of NbCl5 was mixed with the HfCl4 used in the production of CpHf(DMA)3. The method for producing CpZr(DMA)3 was the same as in the above synthesis example, except that ZrCl4 was used as a raw material. Subsequently, tests related to verifying the effect of heat treatment were performed. Details for each of Experimental Examples 1-1 to 1-6 are as follows.

[0051] Experimental Example 1-1. Synthesis experiment of CpHf(DMA)3 by mixing HfCl4 and NbCl5. As an example of metal impurities, to confirm the effect of Nb impurities, we conducted a preliminary investigation into the influence of niobium chloride (NbCl5), which is the most common and abundant impurity, on the CpHf synthesis process.

[0052] The synthesis was carried out in the same manner as in the above synthesis example, except that HfCl4 and NbCl5 were mixed in a constant ratio during the initial reaction. The resulting yellow liquid was distilled at 60°C and 20 mTorr. 1 By measuring 1H-NMR, we were able to confirm that Nb(DMA)5 was generated along with CpHf(DMA)3, and the results are shown in Figure 5.

[0053] Experimental Example 1-2. Separation experiment of a mixture of CpHf(DMA)3 and Nb(DMA)5 A yellow liquid mixture of CpHf(DMA)3 and Nb(DMA)5 synthesized according to Experimental Example 1-1 was distilled at 60°C and 20 mTorr. NMR analysis of the resulting liquid compounds confirmed that CpHf(DMA)3 and Nb(DMA)5 were present in the same manner from the initial to the final distillation. This result confirmed that Nb(DMA)5 could not be removed by distillation. The results are shown in Figure 6.

[0054] Experimental Example 1-3. Heat treatment effect test of a mixture of CpHf(DMA)3 and Nb(DMA)5 The yellow liquid mixture of CpHf(DMA)3 and Nb(DMA)5 synthesized in Experimental Example 1-1 was heat-treated at 140°C for 4 hours to obtain a deep yellow liquid. NMR analysis confirmed that, compared to the stably present CpHf(DMA)3, Nb(DMA)5 was selectively removed through thermal decomposition. This result is shown in Figure 7.

[0055] Experimental Example 1-4. Heat treatment effect test of a mixture of CpZr(DMA)3 and Nb(DMA)5 CpZr(DMA)3 was synthesized in the same manner as in the above synthesis example, except that ZrCl4 was used. The resulting yellow liquid was distilled at 60°C and 20mTorr to obtain a yellow liquid mixture of CpZr(DMA)3 and Nb(DMA)5, which was then heat-treated at 140°C for 4 hours to obtain a deep yellow liquid. NMR measurements confirmed that CpZr(DMA)3 was stably present, while Nb(DMA)5 was selectively removed by thermal decomposition, as shown in Figure 8.

[0056] Experimental Example 1-5. Test of the heat treatment effect of a mixture of CpHf(DMA)3 and Nb(DMA)5 at different temperatures. Furthermore, the decomposition of Nb(DMA)5 over time at temperatures ranging from 120 to 180°C was tested in a pale orange liquid mixture of CpHf(DMA)3 and Nb(DMA)5 synthesized by Experimental Example 1-1. NMR measurements confirmed that Nb(DMA)5 was removed in just 30 minutes at 180°C. The results for removal times at each temperature are shown in Table 1. [Table 1]

[0057] The results in Table 1 confirm that heat treatment is possible in a wide range of temperatures, and that as the temperature increases, even short heat treatment times become effective. Furthermore, when the Nb content is low, the same effect can be obtained with even shorter heat treatment times. It was also confirmed that similar effects can be obtained by adjusting the heat treatment time, even when the experimental evaluation conditions are deviated from.

[0058] Experimental Example 1-6. Comparison of the thermal decomposition behavior of a mixture of CpHf(DMA)3 and Nb(DMA)5. The CpHf(DMA)3 and Nb(DMA)5 synthesized in Synthesis Example 1 were subjected to TGA measurements, and the volatility was compared by overlaying the results. The comparison results are shown in Figure 9. As can be seen from the results in Figure 9, Nb(DMA)5 has a residue of 20% compared to CpHf(DMA)3, indicating that a large amount remains without volatilizing. This result suggests that Nb(DMA)5 exhibits low thermal stability and is easily decomposed by heat, and the decomposed products remain as non-volatile solids.

[0059] Example 1. Tests related to the effect of heat treatment of a mixture containing metal impurities with CpHf(DMA)3. Except for using HfCl4 with different concentrations of metal impurities, the method described in the synthesis example above was applied to prepare CpHf(DMA)3 samples containing various metal impurities. Heat treatment effect-related tests were performed according to Examples 1-1 to 1-10 below. The test results from the examples are summarized in Table 2 below. (The heat treatment refers to applying heat to the sample at the specified temperature for a predetermined time.) [Table 2]

[0060] Details for each of Examples 1-1 to 1-10 are as follows.

[0061] Example 1-1. Comparative test of the effect of heat treatment of CpHf(DMA)3 in a mixture containing metal impurities before purification (Nb 240 ppb) Two samples, Sample 1 and Sample 2, were separated from CpHf(DMA)3 (a pale orange liquid) obtained using HfCl4 containing 240 ppb of Nb. Sample 1 was heat-treated at 140°C for 2 hours to obtain a deep yellow liquid, while Sample 2 was not heat-treated. To confirm the effect of heat treatment on each sample, distillation was performed at 60°C and 20 mTorr to obtain the compound in liquid form. From these results, it was confirmed that the sample heat-treated before purification showed a greater reduction in Nb metal compared to the unheat-treated sample.

[0062] Examples 1-2. Comparative test of the effect of heat treatment of a mixture containing metal impurities before purification (Nb 300 ppb) with CpHf(DMA)3. Samples 3 and 4 were separated into equal amounts from CpHf(DMA)3 (a yellow-orange liquid) obtained using HfCl4 containing 300 ppb of Nb. Sample 3 was heat-treated at 140°C for 2 hours to obtain a deep yellow liquid, while sample 4 was not heat-treated. Each sample was distilled at 60°C and 20 mTorr to obtain the compound in liquid form. From these results, it was confirmed that the sample heat-treated before purification showed a greater reduction in Nb metal compared to the unheat-treated sample.

[0063] Examples 1-3. Comparative test of the effect of heat treatment of CpHf(DMA)3 in a mixture containing metal impurities before purification (Nb 700 ppb) Samples 5, 6, 7, 8, and 9 were separated into equal amounts from CpHf(DMA)3 (an orange-colored liquid) obtained using HfCl4 containing 700 ppb of Nb. Sample 5 was not heat-treated. Sample 6 was heat-treated at 120°C for 6 hours to obtain a deep yellow liquid. Sample 7 was heat-treated at 120°C for 12 hours to obtain a deep yellow liquid. Sample 8 was heat-treated at 140°C for 2 hours to obtain a deep yellow liquid. Sample 9 was heat-treated at 140°C for 4 hours to obtain a deep yellow liquid. Each sample was distilled at 60°C and 20 mTorr to obtain the compound in liquid form. From these results, it was confirmed that the samples heat-treated before purification showed a greater reduction in Nb metal compared to the samples that were not heat-treated.

[0064] Examples 1-4. Comparative test of the effect of CpHf(DMA)3 heat treatment on a mixture containing metal impurities after primary purification (Nb 240 ppb) CpHf(DMA)3 (orange-colored liquid) obtained using HfCl4 containing 240 ppb of Nb was distilled at 60°C and 20 mTorr to obtain a yellow liquid, and equal amounts of samples 10 and 11 were taken from this yellow liquid. Sample 10 was heat-treated at 140°C for 2 hours to obtain a yellow liquid, while sample 11 was not heat-treated. Each sample was distilled at 60°C and 20 mTorr to obtain the compound in liquid form. From these results, it was confirmed that the sample heat-treated after primary purification showed a greater reduction in Nb metal compared to the sample that was not heat-treated.

[0065] Examples 1-5. Comparative test of the effect of CpHf(DMA)3 heat treatment on a mixture containing metal impurities after primary purification (Nb3 13 ppb) CpHf(DMA)3 (a pale orange liquid) obtained using HfCl4 containing 313 ppb of Nb was distilled at 60°C and 20 mTorr to obtain a yellow liquid, and equal amounts of samples 12 and 13 were taken from this yellow liquid. Sample 12 was heat-treated at 140°C for 2 hours to obtain a yellow liquid, while sample 13 was not heat-treated. Each sample was distilled at 60°C and 20 mTorr to obtain the compound in liquid form. From these results, it was confirmed that the sample heat-treated after primary purification showed a greater reduction in Nb metal compared to the sample that was not heat-treated.

[0066] Examples 1-6. Comparative test of the effects of CpHf(DMA)3 heat treatment conditions on a mixture containing metal impurities after primary purification (Nb 240 ppb) CpHf(DMA)3 (a pale orange liquid) obtained using HfCl4 containing 240 ppb of Nb was distilled at 60°C and 20 mTorr to obtain a yellow liquid, and equal amounts of samples 14, 15, and 16 were taken from this yellow liquid. Sample 14 was heat-treated at 140°C for 2 hours, sample 15 at 120°C for 4 hours, and sample 16 at 120°C for 12 hours to obtain yellow liquids. Each sample was distilled at 60°C and 20 mTorr to obtain the compound in liquid form. From these results, it was confirmed that there is an effect of reducing Nb depending on the heat treatment temperature and time between samples that underwent heat treatment after primary purification, but no significant difference occurs depending on the reaction conditions.

[0067] Examples 1-7. Comparison of color after heat treatment of CpHf(DMA)3 (Nb 240 ppb) Samples 17 and 18 were separated into equal amounts from CpHf(DMA)3 (a pale orange liquid) obtained using HfCl4 containing 240 ppb of Nb. Sample 17 was heat-treated at 120°C for 12 hours to obtain a deep yellow liquid, while sample 18 was not heat-treated. Each sample was distilled at 60°C and 20 mTorr to obtain the compound in liquid form. As shown in Figure 10, sample 17, which was heat-treated, showed a pale yellow color, while sample 18, which was not heat-treated, showed a yellow color. From these results, it was confirmed that the heat-treated sample showed improvement in color compared to the unheat-treated sample.

[0068] Examples 1-8. Comparison of color by purification order after heat treatment of CpHf(DMA)3 (Nb 240 ppb) Samples 19 and 20 were separated into equal amounts from CpHf(DMA)3 (a pale orange liquid) obtained using HfCl4 containing 240 ppb of Nb. Sample 19 was heat-treated at 120°C for 12 hours to obtain a deep yellow liquid, while sample 20 was not heat-treated. Each sample was subjected to primary distillation at 60°C and 20 mTorr to obtain the liquid compounds, and their colors were compared. Then, the same samples were subjected to secondary distillation at 60°C and 20 mTorr to obtain the liquid compounds, and their colors were compared. Subsequently, the same samples were subjected to tertiary distillation at 60°C and 20 mTorr to obtain the liquid compounds, and their colors were compared. The results are shown in Table 3. The results of observing the color changes at each stage are shown in the photograph in Figure 11. [Table 3]

[0069] From the results above, it was confirmed that the heat-treated samples maintained a sustained improvement in terms of color and Nb content even during the continuous distillation process, compared to the untreated samples. Furthermore, it was confirmed that the Nb content of the heat-treated primary purified sample was similar to that of the untreated tertiary purified sample, indirectly confirming that heat treatment provides an effect equivalent to about two purification cycles.

[0070] Examples 1-9. Comparison of color by purification order of CpHf(DMA)3 by heat treatment (Nb 240 ppb) Sample 21 was separated from CpHf(DMA)3 (a pale orange liquid) obtained using HfCl4 containing 240 ppb of Nb. Sample 21 was heat-treated at 140°C for 5 minutes to obtain a deep yellow liquid. Sample 21 was primary distilled at 60°C and 20 mTorr to obtain a liquid compound, then secondary distillation at 60°C and 20 mTorr to obtain a liquid compound, and finally tertiary distillation at 60°C and 20 mTorr to obtain a liquid compound. The colors of each purification order were then compared. As shown in Figure 12, the pale orange crude product sample changed to deep yellow after heat treatment, remained pale yellow after primary purification, became even paler yellow after secondary purification, and became colorless after tertiary purification. These results confirm that the improvement in color is sustained even in samples that underwent short-time heat treatment and in samples that underwent continuous distillation.

[0071] Examples 1-10. High-temperature purification test of CpHf(DMA)3 in a mixture containing metal impurities before purification (Nb 240 ppb) Sample 22 was separated from CpHf(DMA)3 (a pale orange liquid) obtained using HfCl4 containing 240 ppb of Nb. Sample 22 was distilled at a higher purification temperature and pressure than existing conditions, 120°C and 1 Torr, to obtain a pale yellow liquid compound. From these results, it was confirmed that even when heat-treated samples are purified at high temperatures, they still exhibit an Nb metal reduction effect.

[0072] 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 those with ordinary skill in the art to which the invention pertains, without departing from the spirit of the invention. Such modifications and alterations should be understood to be within the scope of the present invention and the appended claims.

Claims

1. A method for producing a precursor for forming a high-purity group IV transition metal-containing thin film, characterized by including a step of heat-treating a group IV transition metal compound at a heat treatment temperature.

2. A method for producing a high-purity group IV transition metal-containing thin film formation precursor according to claim 1, characterized in that the heat treatment temperature is 80 to 240°C.

3. The method for producing a high-purity group IV transition metal-containing thin film precursor according to claim 1, characterized in that the heat treatment step is performed at the heat treatment temperature for 0.01 to 48 hours.

4. The method for producing a high-purity group IV transition metal-containing thin film formation precursor according to claim 1, characterized in that the heat treatment step involves raising the temperature from room temperature to the heat treatment temperature at a heating rate of 0.1 to 10°C / min, and then performing the heat treatment.

5. A method for producing a high-purity group 4 transition metal-containing thin film formation precursor according to claim 1, characterized by comprising the step of purifying the group 4 transition metal compound at least once before or after heat treatment of the group 4 transition metal compound.

6. The method for producing a high-purity group 4 transition metal-containing thin film formation precursor according to claim 5, characterized in that the purification step involves purifying the group 4 transition metal compound by vacuum distillation.

7. The method for producing a high-purity group 4 transition metal-containing thin film formation precursor according to claim 1, characterized in that the niobium (Nb) content of the high-purity group 4 transition metal-containing thin film formation precursor is reduced by 40% or more compared to the group 4 transition metal compound.

8. The method for producing a high-purity group 4 transition metal-containing thin film precursor according to claim 1, wherein the heat treatment step is characterized by i) heat treatment in a container on which the group 4 transition metal compound is supported, ii) heat treatment of the group 4 transition metal compound in a transfer section where it is moved from the container to another container, or iii) heat treatment of the group 4 transition metal compound in the container on which the group 4 transition metal compound is supported and in a transfer section where it is moved from the container to another container.

9. A thin-film formation precursor manufactured by heat-treating a group 4 transition metal compound at a heat treatment temperature, characterized in that the niobium (Nb) content is reduced by 40% or more compared to the group 4 transition metal compound, wherein the niobium (Nb) content is reduced by 40% or more compared to the group 4 transition metal compound.

Images