High-purity dichloromolybdenum dioxide and preparation method thereof

Abstract

The present invention relates to a high-purity molybdenum dichloride having a silicon (Si) content of 400 ppm by weight or less in impurities, and a method for preparing the same, and more particularly, to a high-purity molybdenum dichloride which can be produced by a sublimation purification process to obtain high-purity molybdenum dichloride, and to a method for preparing the same.

Description

Technical Field

[0001] The present invention relates to a high-purity molybdenum dioxide dichloride (MoO2Cl2) and a preparation method thereof, and in particular to a high-purity molybdenum dioxide dichloride suitable for use as a precursor for thin film formation by removing impurities that cause an increase in specific resistance and a preparation method thereof. Background Art

[0002] In order to form a high-quality thin film, it is necessary to prepare molybdenum dioxide dichloride (MoO2Cl2), which can be used as a precursor for forming a molybdenum-containing thin film, into a high-purity compound.

[0003] The high-purity molybdenum dioxide dichloride has been disclosed in prior arts such as Korean Registered Patent Publication No. 10-2368870 and Korean Published Patent Publication No. 10-2020-0127226.

[0004] In Korean Patent Publication No. 10-2020-0127226, high-purity molybdenum oxychloride is disclosed, and in Korean Registered Patent Publication No. 10-2368870, high-purity molybdenum oxychloride is disclosed, and molybdenum dichloride is mentioned as an example of the molybdenum oxychloride. In addition, in International Patent Publication No. 2021-171742, high-purity molybdenum oxychloride is disclosed.

[0005] In the prior art, as a method for confirming the purity of the compound, the contents of Be, Mg, Al, Ga, Ge, As, Sr, Ba, W, Ti, U, Ag, Na, Co, Fe, In, Mn, Ni, Pb, Zn, Cu, Cr, Tl, Li, Th, Sc, Se, Hf, Ta and Bi are analyzed by inductively coupled plasma mass spectrometry (ICP-MS), and the content of K is analyzed by atomic absorption spectrometry (AAS), and the purity is calculated based on the result values.

[0006] Based on the contents of the above-mentioned prior art, the applicant has studied the performance of molybdenum dioxide dichloride as a precursor for thin film formation, and confirmed that among the various impurities, there are impurities such as silicon (Si) that are not mentioned in the prior art. In particular, when the content of silicon reaches a certain level, it may cause an increase in the resistivity of the formed film, and may cause problems in the process of forming a high-quality molybdenum-containing film.

[0007] This confirmed that only when high-purity molybdenum dioxide dichloride is used, which removes impurities that may cause problems when used as a precursor for thin film formation, it is conducive to forming a high-quality molybdenum-containing thin film. Summary of the invention

[0008] 1. Technical issues to be resolved

[0009] The present invention aims to solve the problems existing in the prior art as described above, and its purpose is to provide a molybdenum dioxide dichloride (MoO2Cl2) which can be purified to a high purity by reducing the content of impurities that may cause a decrease in film properties and a preparation method thereof.

[0010] (II) Technical solution

[0011] In order to achieve the above-mentioned object, the molybdenum dioxide dichloride of the present invention is characterized in that the content of silicon (Si) in impurities is 400 wtppm or less.

[0012] At this time, the impurities may contain 99 wt % or more of silicon (Si).

[0013] Furthermore, in one embodiment, the content of the remaining impurity components in the impurities except silicon (Si) may be less than 2 wtppm, and in another embodiment, the content of the remaining impurity components in the impurities except silicon (Si) may be less than 0.1 wtppm.

[0014] In addition, the impurities may be silicon (Si), silver (Ag), aluminum (Al), arsenic (As), gold (Au), barium (Ba), calcium (Ca), cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), iron (Fe), potassium (K), lithium (Li), magnesium (Mg), manganese (Mn), sodium (Na), nickel (Ni), lead (Pb), antimony (Sb), tin (Sn), titanium (Ti), vanadium (V), tungsten (W), zinc (Zn) and zirconium (Zr).

[0015] Furthermore, in one embodiment, the content of hydrates in the molybdenum dioxide dichloride may be less than 1.5 wt %, and in another embodiment, the content of hydrates may be less than 1 wt %.

[0016] In addition, the high-purity molybdenum dioxide dichloride can be manufactured by a process of sublimating and purifying molybdenum dioxide dichloride.

[0017] (III) Beneficial effects

[0018] The molybdenum dioxide dichloride according to the present invention is purified to a high purity, and therefore, when used as a precursor in a thin film forming process, can exhibit an effect of reducing the content of impurities that may deteriorate the characteristics of the produced thin film. DETAILED DESCRIPTION

[0019] Next, the present invention will be described in more detail. The terms or words used in this specification and claims should not be interpreted in a limited manner according to the common or dictionary meanings, but should be interpreted in accordance with the meanings and concepts that are consistent with the technical ideas of the present invention, based on the principle that the inventor can appropriately define the concepts of the terms in order to describe his invention in the best way.

[0020] Generally speaking, molybdenum dioxide dichloride (MoO2Cl2) contains trace amounts of impurities such as silicon (Si), silver (Ag), aluminum (Al), arsenic (As), gold (Au), barium (Ba), calcium (Ca), cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), iron (Fe), potassium (K), lithium (Li), magnesium (Mg), manganese (Mn), sodium (Na), nickel (Ni), lead (Pb), antimony (Sb), tin (Sn), titanium (Ti), vanadium (V), tungsten (W), zinc (Zn), and zirconium (Zr). In addition, due to its high hygroscopicity, it may absorb moisture from the air and form hydrates.

[0021] When the molybdenum dioxide dichloride is used as a precursor for a process for forming a thin film, it is important to reduce the moisture content of the raw material itself and prevent it from coming into contact with air during the process.

[0022] Even if the moisture problem is solved, other problems may still arise in the film forming process, such as the degradation of film properties due to the presence of impurities. In order to solve the above problems, a high-purity molybdenum oxychloride compound is used in the prior art.

[0023] However, when the molybdenum dioxide dichloride in the molybdenum oxychloride compound is applied to actual engineering, the resistivity of the formed film may increase, and it has been found that this is the effect of silicon (Si) in the impurities contained in the molybdenum dioxide dichloride.

[0024] Therefore, in the present invention, molybdenum dioxide dichloride having a silicon content of 400 wt ppm or less in the impurities is used as a precursor for film formation, thereby solving the problem of decreased film properties as described above. When the silicon content in the impurities is 400 wt ppm or less, the problem of increased specific resistance of the formed film can be solved, thereby forming a high-quality molybdenum-containing film.

[0025] The content of the impurities can be defined as the sum of the contents of the elements whose content is above the detection limit as 100 weight % (wt%) and the value of the contents of the remaining components is deducted therefrom. Specifically, the silicon content can be measured by inductively coupled plasma optical emission spectroscopy (ICP-OES), and the remaining impurity components other than the silicon can be measured by inductively coupled plasma mass spectrometry (ICP-MS). The value calculated by the measurement method can be used as a value for determining the purity of the molybdenum dioxide dichloride.

[0026] The molybdenum dioxide dichloride can be produced by reacting sodium molybdate (Na2MoO4) with thionyl chloride (SOCl2).

[0027] Specifically, sodium molybdate and thionyl chloride are reacted through a single-stage reaction, and the reaction is performed at room temperature and under reflux conditions, so that high-purity molybdenum dioxide dichloride can be obtained without side reactions.

[0028] In the synthesis method, after sodium molybdate is reacted with thionyl chloride to form NaMoO4-SOCl, SO2 is removed to form sodium molybdenum oxychloride (NaMoO3Cl) as an intermediate, and then molybdenum dioxide dichloride (MoO2Cl2) is generated by reacting the sodium molybdenum oxychloride with thionyl chloride via MoO3Cl-SOCl.

[0029] In addition, the reaction can be performed in the presence of a reaction solvent. As the reaction solvent, a 10 Straight chain, branched or cyclic saturated or unsaturated hydrocarbons, alkyl halides (RH a X (4-a) (X=Cl, Br, or I)). As the hydrocarbon, hexane, cyclohexane, octane or decane can be exemplified, and as the alkyl halide, dichloromethane, chloroform or carbon tetrachloride can be exemplified.

[0030] In addition, molybdenum dichloride can also be obtained by a two-stage synthesis method in which molybdenum oxytetrachloride (MoOCl4) is synthesized and then used as a raw material to synthesize molybdenum dichloride (MoO2Cl2).

[0031] In the reaction, the first stage reaction uses molybdenum oxide (MoO3) as a raw material. After the molybdenum oxide is reacted with thionyl chloride (SOCl2), the unreacted components are removed, and molybdenum tetrachloride is obtained by sublimation purification. Next, in the second stage reaction, hexamethyldisiloxane (HMDSO) can be added dropwise after the molybdenum tetrachloride is mixed with a reaction solvent to react, and then molybdenum dichloride is obtained by filtering and washing.

[0032] By sublimating and purifying the molybdenum dioxide dichloride obtained by the synthesis method described above, high-purity molybdenum dioxide dichloride can be obtained.

[0033] In the sublimation purification process, molybdenum dioxide dichloride can be obtained by placing molybdenum dioxide dichloride into a sublimation purification machine and heating it to the sublimation temperature of the raw material to sublime it and then re-condensing it.

[0034] Next, the effects of the present invention will be described by way of examples.

[0035] [Synthesis example 1]

[0036] MoOCl4 is synthesized in the first stage reaction.

[0037] After MoO3 is added to the reaction vessel, nitrogen (N2) is used for purging. Next, 5 equivalents of SOCl2 are added and reacted under heating reflux. When reacting, the reaction solution becomes dark red and MoO3 is exhausted in a suspended state. After 8 hours, the reaction is terminated and cooled to room temperature. Next, unreacted MoO3 is removed by filtering the reaction solution, and the remaining SOCl2 is removed by concentrating the filtrate under reduced pressure. After completing the concentrating under reduced pressure, a dark green solid (MoOCl4crude) is obtained. High-purity MoOCl4 is obtained by sublimating and purifying the obtained MoOCl4.

[0038] Next, MoO2Cl2 is synthesized in the second stage reaction.

[0039] After MoOCl4 is added to the reaction vessel, nitrogen (N2) is used for purging. Next, after adding 7 volume % (vol%) of the reaction solvent, i.e., dichloromethane (DCM), stirring is carried out at room temperature. After the solution becomes dark red, 1 equivalent of hexamethyldisiloxane (HMDSO) is slowly added dropwise. In the process of adding hexamethyldisiloxane (HMDSO), a brown solid is slowly generated, and when the addition is completed, it is converted into a brown suspension. The reaction is carried out at room temperature for 12 hours, and after the reaction is completed, the solid is filtered, and then washed with the reaction solvent, i.e., dichloromethane (DCM), until the filtrate becomes clear. The filtered solid is vacuum dried to obtain a crude MoO2Cl2.

[0040] [Synthesis example 2]

[0041] After Na2MoO4 is added to the reaction vessel, nitrogen (N2) is used for purging. Next, 2 equivalents of SOCl2 and 7.5% by volume of dichloromethane (DCM) are added and reacted under heating reflux conditions. After 6 hours of reaction, the reaction is terminated and cooled to room temperature. After filtering the obtained solid, the reaction solvent, i.e., dichloromethane (DCM), is used for washing until the filtrate becomes clear. The filtered and washed solid is vacuum dried to obtain MoO2Cl2 crude.

[0042] [Example 1]

[0043] The MoO2Cl2 obtained in Synthesis Example 1 was sublimated and purified by a sublimation purifier under the following conditions.

[0044] MoO2Cl2 was placed in a raw material container of a sublimation purifier and maintained at a heating temperature of 151°C, which allows the raw material to be stably sublimated. Under the above-mentioned state, MoO2Cl2 was precipitated, which sublimated and re-condensed toward the recovery part of the sublimation purifier. During the re-condensation process, the temperature of the recovery part was 50°C, and the vacuum degree was maintained at 6.5 Torr.

[0045] [Example 2]

[0046] The MoO2Cl2 obtained in Synthesis Example 2 was sublimated and purified by a sublimation purifier under the following conditions.

[0047] MoO2Cl2 was placed in a raw material container of a sublimation purifier and maintained at a heating temperature of 151°C, which allows the raw material to be stably sublimated. Under the above-mentioned state, MoO2Cl2 was precipitated which sublimated and re-condensed toward the recovery part of the sublimation purifier. The temperature of the recovery part during the re-condensation was 50°C, and the vacuum degree was maintained at 6.5 Torr.

[0048] [Example 3]

[0049] The MoO2Cl2 obtained in Synthesis Example 1 was sublimated and purified by a sublimation purifier under the following conditions.

[0050] MoO2Cl2 was placed in a raw material storage container of a sublimation purifier and maintained at a heating temperature of 151°C, which allows the raw material to be stably sublimated. By maintaining the above state, MoO2Cl2 was precipitated which sublimated and re-condensed toward the recovery part of the sublimation purifier. The temperature of the recovery part during the re-condensation was 50°C, and the vacuum degree was maintained at 6.5 Torr.

[0051] [Impurity content analysis]

[0052] The impurity content of the molybdenum dioxide dichloride obtained by Synthesis Examples 1 to 2 and Examples 1 to 3 was analyzed. The silicon content in the impurities was analyzed using inductively coupled plasma emission spectrometry (ICP-OES), and the content of the remaining impurity components other than silicon was analyzed using inductively coupled plasma mass spectrometry (ICP-MS). The results are shown in Table 1. In Table 1, the unit of silicon content is ppm, and the unit of the content of the remaining impurities is ppb.

[0053] [Table 1]

[0054]

[0055] It can be confirmed from the results in Table 1 that silicon accounts for the vast majority of the impurities contained in MoO2Cl2. In addition, the content of sodium is relatively high among the impurities other than silicon because NaCl is generated as a by-product during the synthesis process.

[0056] In addition, the results of quantitative analysis of the contents of MoO2Cl2 and hydrates by X-ray diffraction (XRD) analysis are shown in Table 2. The quantitative analysis is a relative value calculated from the peak area, and the unit is weight %.

[0057] [Table 2]

[0058]

[0059] The analysis results in Tables 1 and 2 show that the silicon (Si) content in the impurities of the molybdenum dioxide dichloride of Examples 1 to 3 is 400 wt ppm or less, thereby confirming that it is a high-purity compound with a low silicon content. In addition, the hydrate content is 1.5 wt % or less, thereby confirming that it is a high-purity molybdenum dioxide dichloride containing almost no hydrate.

[0060] In the above content, the present invention is described by taking a preferred embodiment as an example, but the present invention is not limited to the embodiment, but can be modified and changed in various ways by a person having general knowledge in the technical field to which the present invention belongs within the scope of the gist of the present invention. The modified examples and changed examples should be deemed to be included in the scope of the present invention and the appended claims.

Claims

1. A high-purity molybdenum dioxide dichloride, characterized in that, The content of silicon (Si) in the impurities is 400 wtppm or less.

2. The high-purity molybdenum dioxide dichloride according to claim 1, characterized in that The impurities contain 99% by weight or more of silicon (Si).

3. The high-purity molybdenum dioxide dichloride according to claim 1, characterized in that The content of the impurities other than silicon (Si) is less than 2 wt ppm.

4. The high-purity molybdenum dioxide dichloride according to claim 1, characterized in that The content of the impurities other than silicon (Si) is less than 0.1 wt ppm.

5. The high-purity molybdenum dioxide dichloride according to claim 1, characterized in that The impurities are silicon (Si), silver (Ag), aluminum (Al), arsenic (As), gold (Au), barium (Ba), calcium (Ca), cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), iron (Fe), potassium (K), lithium (Li), magnesium (Mg), manganese (Mn), sodium (Na), nickel (Ni), lead (Pb), antimony (Sb), tin (Sn), titanium (Ti), vanadium (V), tungsten (W), zinc (Zn) and zirconium (Zr).

6. The high-purity molybdenum dioxide dichloride according to claim 1, characterized in that The hydrate content in the molybdenum dioxide dichloride is less than 1.5 wt %.

7. The high-purity molybdenum dioxide dichloride according to claim 1, characterized in that The hydrate content in the molybdenum dioxide dichloride is less than 1% by weight.

8. A method for preparing high-purity molybdenum dichloride, characterized in that: Including the sublimation and purification project of molybdenum dioxide dichloride.

Images