WO2024248470A1 - Method for manufacturing aluminum nitride - Google Patents

Abstract

The present invention relates to a method for manufacturing aluminum nitride. The present invention provides a method capable of manufacturing aluminum nitride at a low process temperature. The method for manufacturing aluminum nitride, according to an embodiment of the present invention, comprises the steps of: preparing AlH₃ powder; heating the AlH₃ powder to less than 1000°C in an N₂ atmosphere; and cooling the AlN powder formed by heating the AlH₃ powder.

Description

Aluminum nitride manufacturing method

The present invention relates to a method for producing aluminum nitride. The present invention provides a method capable of producing aluminum nitride at a low process temperature.

Aluminum nitride (AlN) is a solid nitride of aluminum. It has a thermal conductivity of up to 321 W/(m K), which is more than 10 times that of alumina, and an electrical conductivity of 10 ^-11 to 10 ^-13 Ω ^-1 ·cm ^-1 . Because aluminum nitride has excellent thermal conductivity and electrical insulation, it is widely used as an electronic device material and a heat dissipation material.

There are several methods for manufacturing aluminum _nitride , including carbothermal reduction, chemical vapor synthesis, and plasma synthesis. The carbothermal reduction method is a method in which _Al2O3 , C( _CH4 ), and _N2 are reacted to produce AlN and CO, the chemical vapor synthesis method is a method in which _AlCl3 and _NH3 are reacted using a chemical vapor method to produce AlN and _NH4 Cl, and the plasma synthesis method is a method in which AlN is produced by striking the target aluminum metal with plasma in an ammonia or nitrogen atmosphere. All of the conventional manufacturing methods have the disadvantages of being difficult to meet process conditions and high manufacturing costs because they are all performed at temperatures close to or higher than 1000℃. Japanese Patent Publication No. 6345533, a prior art document, discloses a method for producing aluminum nitride by reducing alumina granules by a reduction method, but it is not suitable for obtaining high-purity aluminum nitride and has the same problem as the prior art in that it reacts by heating at a high temperature of 1580 to 1900°C.

The purpose of the present invention is to provide a manufacturing method capable of manufacturing aluminum nitride at a low temperature.

In addition, the present invention can produce high-purity, fine powder-form aluminum nitride.

In addition, the present invention can reduce the amount of energy used and the amount of carbon generated when manufacturing aluminum nitride.

Additionally, the present invention can reduce manufacturing costs.

A method for manufacturing aluminum nitride according to an embodiment of the present invention comprises the steps of: preparing AlH ₃ powder; heating the AlH ₃ powder to less than 1000° C. in an N ₂ atmosphere; and cooling AlN powder formed by heating the AlH ₃ powder.

In the above heating step, the heating temperature can be 600 to 900 ℃.

The above heating step can be performed in an N ₂ atmosphere in which the concentration of moisture and oxygen is maintained at 100 ppm or less.

The step of preparing AlH ₃ powder may include a step of dissolving AlCl ₃ and LiAlH ₄ in a solvent and reacting them; a step of removing a precipitate produced by the reaction from the solution; and a step of producing AlH ₃ powder while supplying an inert gas to the solution from which the precipitate has been removed.

A method for producing aluminum nitride according to an embodiment of the present invention can produce aluminum nitride at a low temperature.

In addition, the present invention can produce high-purity, fine powder-form aluminum nitride.

In addition, the present invention can reduce the amount of energy used and the amount of carbon generated when manufacturing aluminum nitride.

Additionally, the present invention can reduce manufacturing costs.

Figure 1 shows the results of XRD analysis of AlH ₃ powder manufactured according to an embodiment of the present invention.

Figures 2 to 4 show the XRD analysis results of AlN powder manufactured according to an embodiment of the present invention.

Figure 5 is a SEM photograph of the AlN powder of Example 3.

Figure 6 is the result of XRD analysis before heat treatment of Al powder, which is comparative example 1 of the present invention.

Figure 7 shows the results of XRD analysis after heat treatment of Al powder, which is comparative example 1 of the present invention.

Fig. 8(a) is a photograph of the AlN powder of Comparative Example 1 (after heat treatment), and Fig. 8(b) is a SEM photograph of Comparative Example 1 (after heat treatment).

Hereinafter, preferred embodiments of the present invention will be described with reference to the attached drawings. However, the embodiments of the present invention may be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below. In addition, the embodiments of the present invention are provided so that a person having average knowledge in the relevant technical field can more completely explain the present invention. Throughout the specification, the term "including" a certain component does not exclude other components, but rather means that other components can be further included, unless specifically stated otherwise.

A method for manufacturing aluminum nitride according to an embodiment of the present invention comprises the steps of: preparing AlH ₃ powder; heating the AlH ₃ powder to less than 1000° C. in an N ₂ atmosphere; and cooling AlN powder formed by heating the AlH ₃ powder.

In the step of preparing the AlH ₃ powder, the AlH ₃ powder prepared may be fine and high in purity. In one embodiment, the AlH ₃ powder may be prepared by solution reaction of AlCl ₃ and LiAlH ₄ . By using the AlH ₃ powder prepared in this manner, high-purity AlN powder can be prepared even at a low temperature. The AlH ₃ powder may have an average particle size of several to several hundred µm, preferably 1 to 10 µm.

The method for manufacturing AlH ₃ powder in this step may include a step of dissolving AlCl ₃ and LiAlH ₄ in a solvent and reacting them; a step of removing a precipitate produced by the reaction from the solution; and a step of producing AlH ₃ powder while supplying an inert gas to the solution from which the precipitate has been removed.

In the step of dissolving AlCl ₃ and LiAlH ₄ in a solvent and reacting them, AlCl ₃ and LiAlH ₄ are in powder form and can be added at a molar ratio of 1:3, and preferably, LiAlH ₄ can be added so that the molar ratio of AlCl ₃ exceeds 1:3. The solvent can be used in an amount that AlCl ₃ and LiAlH ₄ can sufficiently dissolve. The solvent is not particularly limited as long as it can dissolve AlCl ₃ and LiAlH ₄ , and preferably, it can be an organic solvent. In one embodiment, the solvent can be dibutyl ether. This step can be performed by various mixers, stirrers, etc., and can be performed at room temperature. In this step, AlCl ₃ and LiAlH ₄ react to generate AlH ₃ and LiCl, and LiCl can be precipitated as a solid.

The step of removing the precipitate produced by the reaction from the above solution is a step of removing LiCl and other byproducts. Filtering in this step can apply various filtering or precipitation methods used in the relevant field and is not particularly limited. In one embodiment, this step can be performed by passing the solution through a filter made of paper or fiber.

The step of producing the above AlH ₃ powder can be performed by various processes, but can be performed while supplying an inert gas such as N ₂ or Ar in order to produce high-purity AlH ₃ powder. This is because AlH ₃ dissolved in a solvent can react rapidly with moisture and oxygen. The inert gas can be supplied heated to a temperature of 200° C. or lower, preferably 30 to 50° C. When the temperature of the inert gas exceeds 200° C., some of the produced AlH ₃ powder is decomposed into Al and H ₂ again, which causes a problem in that the purity of the AlH ₃ powder is lowered. The produced AlH ₃ powder can be obtained through filtering.

In one embodiment, the step of generating the AlH ₃ powder can be performed by placing the solution in which AlH ₃ is generated into a reactor, and a condenser can be installed in the reactor to prevent AlH ₃ in the solution from being evaporated and lost or from being exposed to the external environment and reacting. In this case, the inert gas can be supplied in the form of bubbles to the solution in which AlH ₃ is generated, and the average particle size of the bubbles can be supplied in the form of microbubbles or nanobubbles having a size of several tens of nanometers to several hundred micrometers. Through this, the bubbles can be evenly distributed throughout the solution in which AlH ₃ is generated.

Next, a step of heating the prepared AlH ₃ powder to less than 1000°C in a N ₂ atmosphere is performed. This step causes the Al nucleus produced during the decomposition process of AlH ₃ to react with N ₂ , and causes the H ₂ produced together during the decomposition process to first react with trace amounts of oxygen and moisture that may exist in the surroundings, thereby synthesizing high-purity AlN. The heating temperature in this step may be preferably 600 to 900°C, and more preferably 850 to 950°C.

Since Al has very good reactivity with oxygen (O ₂ ) and moisture (H ₂ O), there is a problem that Al ₂ O ₃ and Al(OH) ₃ compounds are formed even at room temperature if oxygen or moisture is present during the decomposition process of AlH ₃ in the solution. In this case, if an inert gas, particularly a nitrogen (N ₂ ) atmosphere, is formed, the Al nucleus created during the decomposition process does not react with oxygen or moisture, so that it exists as Al nuclei and H ₂ in the solution. Here, H ₂ first reacts with a trace amount of oxygen or moisture contained in the supplied nitrogen (N ₂ ) gas to prevent the Al nuclei from being oxidized or hydroxylated, and allows the Al nuclei to react with nitrogen (N ₂ ) to synthesize high-purity AlN. Preferably, the oxygen and moisture concentrations of the N ₂ atmosphere in this step can be 100 ppm or less.

To explain the reaction in this step more specifically, _AlH3 is decomposed in the process of being heated below 1000℃, generating Al nuclei and _H2 . The Al nuclei are very small in size and have a large surface area, so that a reaction with the surrounding environment can occur very quickly. This can increase the reaction efficiency with _N2 even at low temperatures, and thus dramatically reduce the amount of energy used in the production of AlN.

At this stage, _N2 gas can be supplied at a flow rate of 0.5 to 2 l/min, the heating rate can be 3 to 10 ℃/min, and the heating temperature can be maintained for 1 to 3 hours after reaching the temperature.

Next, the heated reactant can be cooled to obtain AlN. The cooling process can be performed by placing the heated reactant in a furnace and slowly cooling it, and is not particularly limited.

Aluminum nitride manufactured through the above method is in powder form and may have an average particle diameter of several tens nm to several µm, and preferably, the average particle diameter of the powder may be 1 µm or less.

Manufacturing Example: Manufacturing of AlH ₃ Powder

AlCl ₃ and LiAlH ₄ (8 g each) were added to 300 ml of dibutyl ether, and the mixture was stirred at room temperature for 1 hour. After stirring, the by-products were filtered out and only the clear solution was taken. The solution was transferred to a three-necked flask, and a N ₂ gas inlet tube was connected to one inlet, a reflux condenser for inducing solvent evaporation and condensation was connected to the other inlet, and the final inlet was blocked with a rubber stopper. N ₂ gas heated to 40 ℃ was injected at a rate of 100 ml/min into the three-necked flask, and the reaction was performed for 4 hours. After the reaction was completed, the solution was poured onto a filter paper in a nitrogen chamber where the oxygen and moisture concentrations were maintained at 100 ppm or less, and the precipitated reactant was obtained. Isopropyl ether was poured onto the obtained precipitate to remove residual dibutyl ether, and the precipitate was washed and dried to obtain AlH ₃ powder.

Experimental Example: XRD Analysis of AlH ₃ Powder

The XRD of the AlH ₃ powder manufactured in the manufacturing example was measured using X'pert pro MPD, and the results are shown in Fig. 1. Referring to Fig. 1, it can be confirmed that high-purity AlH ₃ powder was manufactured.

Manufacturing Example: Manufacturing of AlN Powder

Example 1: 1 g of the previously manufactured AlH ₃ powder was placed in a ceramic container and placed in a heat treatment furnace capable of atmosphere control. N ₂ gas was supplied to the heat treatment furnace at a rate of 1.0 ml/min, and the internal temperature was increased to 700°C at a rate of 5°C/min. After maintaining it in that state for 2 hours, the heat treatment furnace was allowed to cool gradually to cool the product, AlN.

Example 2: AlN was manufactured in the same manner as in Example 1, except that the temperature of the heat treatment furnace was increased to 800°C.

Example 3: AlN was manufactured in the same manner as in Example 1, except that the temperature of the heat treatment furnace was increased to 900°C.

Comparative Example 1: AlN was manufactured in the same manner as in Example 3, except that Al powder having an average particle size of 5 µm was used instead of the previously manufactured AlH ₃ powder.

Experimental Example: SEM and Visual Observation of AlN

The AlN of Example 3 and Comparative Example 1 were observed by SEM and with the naked eye. Fig. 5 is an SEM photograph of Example 3, and Fig. 8 is a general photograph (a) and an SEM photograph (b) of Comparative Example 1. In the case of Example 3, it can be confirmed that it was manufactured as a powder having an average particle diameter of 100 nm or less, and no clumping was observed even when observed with the naked eye. In the case of Comparative Example 1, as seen in Fig. 8, it can be seen that clumps were formed rather than powder.

Experimental Example: XRD Analysis of AlN

XRD analysis was performed on Examples 1 to 3 using X’pert pro MPD, and the results are shown in Figs. 2 to 4, respectively. In addition, XRD analysis was performed on the Al powder used in Comparative Example 1 before and after heat treatment, and the results are shown in Figs. 6 and 7, respectively.

In Example 1, Al was observed together with AlN, but in Example 2, the Al peak decreased, and in Example 3, the Al peak was not observed. Through this, it can be seen that although AlN is generated by heating at 700°C, if the heating process is performed at a higher temperature, AlN with higher purity can be generated. In particular, it can be seen that only AlN can be obtained when heating to 900°C. In the case of Comparative Example 1, it was confirmed that AlN, Al, and other materials were present after heat treatment.

The present invention is not limited to the above-described embodiments and the attached drawings, but is intended to be limited by the appended claims. Accordingly, various substitutions, modifications, and changes may be made by those skilled in the art within the scope that does not depart from the technical spirit of the present invention as described in the claims, and this will also fall within the scope of the present invention.

Claims (5)

Step of preparing AlH ₃ powder; A step of heating the above AlH ₃ powder to less than 1000 ℃ in an N ₂ atmosphere, and Comprising a step of cooling the AlN powder formed by heating the AlH ₃ powder. Method for manufacturing aluminum nitride. In the first paragraph, In the above heating step, the heating temperature is 600 to 900 ℃. Method for manufacturing aluminum nitride. In the first paragraph, The above heating step is performed in an N ₂ atmosphere in which the concentration of moisture and oxygen is maintained at 100 ppm or less. Method for manufacturing aluminum nitride. In the first paragraph, The average particle size of the aluminum nitride powder manufactured by the present method is 1 µm or less. Method for manufacturing aluminum nitride. In the first paragraph, The steps for preparing AlH ₃ powder are: A step of reacting AlCl ₃ and LiAlH ₄ by dissolving them in a solvent; A step of removing a precipitate produced by the reaction from the above solution; and A step of producing AlH ₃ powder while supplying an inert gas to a solution from which the above precipitate has been removed; Method for manufacturing aluminum nitride.

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