KR100972992B1 - Manufacturing method of aluminum nitride powder and apparatus for chemical vapor synthesis of aluminum nitride powder - Google Patents

Abstract

The present invention comprises the steps of heating the reaction chamber by heating means to maintain a constant temperature of 800 ~ 1400 ℃, heating by using the heating means to vaporize the aluminum source charged in the aluminum source storage unit, vaporization Injecting a nitrogen source gas into the reaction chamber while introducing the prepared aluminum source gas into the reaction chamber, and chemically vapor-phase reaction between the aluminum source gas and the nitrogen source gas in the reaction chamber to form aluminum nitride powder; Collecting the aluminum nitride powder synthesized in the reaction chamber and the reaction by-products in a collector and heat-treating the reaction by-products at a temperature higher than the temperature at which the reaction by-products are pyrolyzed and lower than the temperature at which aluminum nitride is pyrolyzed to remove the collected reaction by-products. Nitriding alu comprising a step of selectively removing It relates to a process for producing a titanium powder and a chemical vapor synthesis apparatus for manufacturing aluminum nitride powder. According to the present invention, a high-purity aluminum nitride nanopowder can be synthesized by chemical vapor phase reaction in an reaction chamber using an aluminum source and a nitrogen source.

Aluminum Nitride Powder, Chemical Vapor Synthesis, Aluminum Source, Nitrogen Source, Capture, Heat Treatment

Description

Manufacturing method of aluminum nitride powder and apparatus for chemical vapor synthesis of aluminum nitride powder

The present invention relates to a method for producing aluminum nitride powder and a chemical vapor synthesis apparatus for producing aluminum nitride powder, and more particularly, to high-purity aluminum nitride nanopowder by chemical vapor phase reaction in a reaction chamber using an aluminum source and a nitrogen source. The present invention relates to a method for producing aluminum nitride powder for synthesizing a compound and a chemical vapor phase synthesis device for producing an aluminum nitride powder.

Aluminum nitride (AlN) is stable at high temperatures, has a low dielectric constant and low dielectric loss, excellent electrical insulation, and thermal conductivity of about 320 W / mK, which has physical properties higher than that of metals. In addition, aluminum nitride (AlN) has a thermal expansion coefficient of about 2.64 × 10 ⁻⁶ / K, which is similar to silicon, and can be used as a filler for a substrate material or a polymer package material of a semiconductor.

Due to such physical properties, aluminum nitride (AlN) may be used as a high thermal conductive insulating substrate, a high corrosion resistant material, and the like. In particular, many researches on the synthesis method have been conducted since they can be used in high-temperature materials such as packages of highly integrated semiconductor chips requiring excellent electrical insulation and heat dissipation, and heat exchangers requiring high thermal conductivity and high corrosion resistance.

Commercially available methods of producing aluminum nitride (AlN) powder include a self-propagating high temperature synthesis method (Self-Propagating High Temperature Synthesis Method), carbon reduction method.

The carbon reduction method is a method of producing aluminum nitride (AlN) by reducing alumina (Al ₂ O ₃ ) powder to carbon (C) in a high temperature nitrogen (N ₂ ) atmosphere. However, in the carbon reduction method, the temperature of the high temperature synthesizer must be maintained at 1800 ° C or higher for the reaction of alumina and nitrogen, and the carbon is added at a temperature of 600 ° C or higher to remove the carbon remaining after the aluminum nitride (AlN) powder is formed because carbon is added as a diluent. In addition, there is a disadvantage in that an additional heat treatment process is required and oxygen remains in the aluminum nitride (AlN) powder. Oxygen present in the aluminum nitride (AlN) is known to be about 0.8 to 2.0% by weight, and such oxygen causes the thermal conductivity to decrease as an impurity of the aluminum nitride (AlN) powder.

Korean Patent Application No. 10-1993-0008310 discloses a method for producing aluminum nitride (AlN) using a carbon reduction method. However, according to Korean Patent Application No. 10-1993- 0008310, since carbon remains in the reactants produced by the carbon reduction method, reheating is performed for 1 to 3 hours at a temperature of 650 ° C to 750 ° C to remove the remaining carbon. There is a separate process. In this process, there is a problem that oxygen, which adversely affects the thermal conductivity of aluminum nitride (AlN), may be mixed as impurities.

The autothermal high temperature synthesis method is a method for synthesizing aluminum nitride (AlN) using the heat generated during the chemical reaction.

Korean Patent Application No. 10-1993-0005742 makes a sample by mixing carbon powder with a metal aluminum powder with a diluent, and tapping the sample into a plate-shaped aluminum powder compact having a predetermined thickness, and charging it into a reactor and the atmospheric gas present in the reactor. It is proposed that a method for producing aluminum nitride powder by igniting a high-temperature autonitrification reaction using an electric arc while maintaining the nitrogen pressure of 3 to 10 atm by removing the. However, a process of pulverizing the sample, which is a mixture of the produced aluminum nitride powder and carbon powder, using a ball mill and the like, and removing the carbon powder by maintaining the pulverized sample at a temperature of 650-750 ° C. in the air or oxygen atmosphere is added. It is difficult to obtain high purity aluminum nitride (AlN) because the process is complicated and the inflow of impurities is large.

Korean Patent Application No. 10-1999-0004068 discloses a powder containing 10 to 90% by weight of aluminum (Al) powder and 10 to 90% by weight of aluminum nitride (AlN) as a reaction regulator. It is proposed to prepare a refractory aluminum nitride powder by the exothermic reaction by using a heating element after the continuous injection into the reactor maintained in cm 2 to form a powder filling layer. However, in this method, since the high temperature of 2,000 ° C. or higher is generated during the high-temperature reaction of the rotating and the aluminum nitride particles grow large, a pulverization and classification process is required after the synthesis. In addition, a large amount of impurities are mixed in this crushing step to cause a decrease in purity.

The technical problem to be achieved by the present invention is to synthesize the aluminum nitride powder by chemical vapor phase reaction in the reaction chamber using an aluminum source and a nitrogen source, to collect the aluminum nitride powder and the reaction by-products in the collector and to selectively remove only the reaction by-products of high purity It is to provide a method for producing aluminum nitride powder to form the aluminum nitride nano powder.

Another object of the present invention is to provide a chemical vapor synthesis apparatus of aluminum nitride powder for synthesizing high purity aluminum nitride nanopowder by chemical vapor phase reaction in a reaction chamber using an aluminum source and a nitrogen source.

The present invention comprises the steps of (a) heating the reaction chamber by heating means to maintain a constant temperature of 800 ~ 1400 ℃, and (b) heating by using the heating means to the aluminum source charged into the aluminum source storage unit Vaporizing, (c) injecting a nitrogen source gas into the reaction chamber while introducing a vaporized aluminum source gas into the reaction chamber, and (d) an aluminum source gas and a nitrogen source gas are chemically vaporized in the reaction chamber. Reacting to form aluminum nitride powder, (e) collecting the aluminum nitride powder synthesized in the reaction chamber and the reaction by-product in a collector, and (f) the temperature at which the reaction by-product is pyrolyzed to remove the collected reaction by-product. Selectively removing reaction byproducts by heat treatment at a temperature higher than the temperature at which aluminum nitride is pyrolyzed. Provides a method of manufacturing aluminum nitride powder.

In the method of manufacturing the aluminum nitride powder, before the step (a), the aluminum source is stored in a vacuum by operating a rotary pump to remove the impurity gas existing in the storage unit, the reaction chamber and the collector and to create a vacuum state Exhausting to a state, injecting a carrier gas into the reaction chamber, and maintaining a uniform amount of exhausted gas after reducing a pumping amount of a pumping unit.

Preferably, a carrier gas is supplied to the reaction chamber and the aluminum source storage unit, nitrogen or an inert gas is used as the carrier gas, and the supply flow rate of the carrier gas is set to about 100 to 500 ml / min.

Preferably, the carrier gas further contains 1 to 3% hydrogen gas in order to remove residual oxygen present in the reaction chamber or the aluminum source reservoir.

Step (b) is to vaporize the aluminum source charged into the aluminum source storage by heating using a heating means, the heating by the heating means is heated by the heating means by applying an indirect heating method and the temperature of the aluminum source storage Is maintained at 100 to 280 ° C., and the conduit between the aluminum source reservoir and the reaction chamber is preferably maintained above a certain temperature using heating means.

In the step (e), the collector comprises a primary collector and a secondary collector, and the cooling water is circulated in the cooling cylinder provided around the primary collector is condensed aluminum nitride and reaction by-products The first collection unit made of stainless steel may be collected, and a Teflon filter having chemical resistance and heat resistance may be used as the secondary collection unit, and the aluminum nitride powder and reaction by-products passing through the primary collection unit may be collected.

The pyrolysis of the reaction byproduct is preferably performed for 30 minutes to 2 hours at a temperature of 200 to 500 ° C. in a nitrogen or inert gas atmosphere.

AlCl ₃ containing aluminum (Al) may be used as the aluminum source, and ammonia (NH ₃ ) and nitrogen (N ₂ ) gas including nitrogen may be used as the nitrogen source.

Aluminum chloride (AlCl ₃ ) is used as the aluminum source, ammonia (NH ₃ ) is used as the nitrogen source, and aluminum chloride (AlCl ₃ ) gas and ammonia (NH ₃ ) gas are chemical vapor phases in the reaction chamber. reaction with aluminum nitride (AlN) powder and the reaction of this is the synthesis of ammonium chloride (NH ₄ Cl) by-product, the ammonium chloride (NH ₄ Cl) ammonium chloride (NH ₄ Cl) from a temperature above the thermal decomposition temperature are to be selectively removed in the Can be.

The formed aluminum nitride powder has a particle diameter of 10 to 80 nm.

The present invention also provides a reaction chamber for synthesizing aluminum nitride powder by chemical reaction between an aluminum source and a nitrogen source, an aluminum source supply unit supplying an aluminum source gas to the reaction chamber, and supplying a nitrogen source gas to the reaction chamber. A nitrogen source supply unit, a carrier gas supply unit serving to transport aluminum source gas and nitrogen source gas to the reaction chamber, a collector for collecting aluminum nitride synthesized in the reaction chamber, and a vacuum for the reaction chamber and the collector. And a pumping unit configured to bring the aluminum nitride (AlN) powder synthesized in the reaction chamber into a collector, wherein the aluminum source supply unit stores an aluminum source and supplies an aluminum source gas to the reaction chamber. To vaporize the reservoir and aluminum source by heating Aluminum nitride powder comprising a heating means, a liquid reservoir for applying an indirect heating method, and a liquid for indirect heating while electrically insulating the aluminum source reservoir between the aluminum source reservoir and the liquid reservoir. Provided is a chemical vapor synthesis apparatus for manufacturing.

The aluminum source reservoir is coated with a Teflon material having heat resistance and chemical resistance, and is in communication with the carrier gas supply part through a conduit for introducing a carrier gas, and around the conduit communicating the aluminum source reservoir with the reaction chamber. Heating means may be provided.

The reaction chamber is made of quartz having thermal shock resistance, and heating means may be provided around the reaction chamber.

The collector includes a cylindrical primary collector of stainless steel having heat resistance and chemical resistance, and a secondary collector for filtering aluminum nitride powder and reaction by-products not captured by the primary collector. A cooling cylinder is provided around the primary collecting unit, and the inside of the cooling cylinder is made to purify the cooling water so that the aluminum nitride powder and the reaction by-product are condensed and stuck to the wall of the primary collecting unit. It can be configured as a filter for filtering out the aluminum nitride powder and the reaction by-products passed through the tea collection unit.

According to the present invention, aluminum nitride (AlN) powder is synthesized by chemical vapor phase reaction in a reaction chamber using an aluminum source and a nitrogen source, and the aluminum nitride powder and the reaction by-product are collected in a collector, and only the reaction by-product is selectively removed to obtain high purity. Aluminum nitride (AlN) can be formed. The obtained high purity aluminum nitride (AlN) nanopowder is excellent in electrical insulation, high in thermal conductivity, excellent in corrosion resistance and chemically stable at high temperature, and can be applied in various fields.

In addition, when the sintered body is manufactured using aluminum nitride (AlN) powder of 500 nm or more, a compact sintered body is obtained only by pressure sintering at a high temperature of 1700 ° C. or higher, but the specific surface area is increased when using the nano-grade aluminum nitride powder prepared according to the present invention. As a result, sinterability is expected to be improved, and thus, a compact nitride sintered body is expected to be manufactured even at low temperature and low pressure.

The present invention has the advantage of obtaining a high-purity aluminum nitride nanopowder in which the manufacturing process is simple and mass production is possible, and oxygen (O ₂ ) does not remain.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the following embodiments are provided to those skilled in the art to fully understand the present invention, and may be modified in various forms, and the scope of the present invention is limited to the embodiments described below. It doesn't happen. Like numbers refer to like elements in the figures.

The present invention proposes a method for producing high purity aluminum nitride (AlN) nanopowder using chemical vapor synthesis (Chemical Vapor Synthesis) method. The present invention synthesizes aluminum nitride (AlN) powder by chemically reacting an aluminum source gas and a nitrogen source gas by applying a chemical vapor phase synthesis method. According to the present invention, high purity aluminum nitride (AlN) nanopowders having a particle diameter of 100 nm or less can be synthesized in a short time. Nano means nanometer (nm) size and is used to mean a size in the range from 1 to 1000 nm.

AlCl ₃ containing aluminum (Al) may be used as the aluminum source, and a gas containing nitrogen may be used as the nitrogen source, such as ammonia (NH ₃ ) and nitrogen (N ₂ ). For example, aluminum chloride (AlCl ₃ ) has the property of subliming at 181.2 ° C. (at 1 atmosphere). By using a low sublimation temperature of the aluminum chloride (AlCl ₃ ) it is possible to synthesize aluminum nitride (AlN) by vaporizing and vapor-phase chemical reaction with the nitrogen (N) component.

1 is a view illustrating a chemical vapor synthesis apparatus according to a preferred embodiment of the present invention.

The chemical vapor synthesis apparatus 100 includes a reaction chamber 110 in which an aluminum source gas and a nitrogen source gas are chemically reacted to synthesize aluminum nitride (AlN) powder, and an aluminum source gas in the reaction chamber 110. The aluminum source supply unit 120 for supplying the nitrogen source, the nitrogen source supply unit 130 for supplying the nitrogen source gas to the reaction chamber 110, and the carrier gas that serves to transport the aluminum source and the nitrogen source to the reaction chamber 110 The supply unit 140, the collector 150 for collecting the aluminum nitride (AlN) powder synthesized in the reaction chamber 110, and the reaction chamber 110 and the collector 150 in a vacuum state in the reaction chamber 110 It includes a pumping unit 160 to induce the synthesized aluminum nitride (AlN) flows to the collector 150.

The reaction chamber 110 includes an inlet 112 through which aluminum source gas, nitrogen source gas, and carrier gas are introduced, and aluminum nitride (AlN) powder synthesized by chemical reaction between aluminum source gas and nitrogen source gas (eg , NH ₄ Cl) comprises an outlet 114 is discharged. The inlet 112 is in communication with the aluminum source supply 120 and the nitrogen source supply 130 via conduits. The outlet 114 is in communication with the collector 150 via a conduit. The reaction chamber 110 has a cylindrical tube shape made of a material having thermal shock resistance, such as quartz. A heater 116 is provided around the reaction chamber 110 between the inlet 112 and the outlet 114. The heating means 116 serves to raise and maintain a constant internal temperature of the reaction chamber 110 to a target temperature (eg, 800 to 1400 ° C.) at which the aluminum source gas and the nitrogen source gas can be reacted and synthesized.

The aluminum source supply unit 120 supplies an aluminum source gas to the reaction chamber 110. The aluminum source supply unit 120 includes an aluminum source storage unit 122 for storing an aluminum source and supplying an aluminum source gas to the reaction chamber 110, and a heater 124 for heating and vaporizing the aluminum source. It includes. The heating means 124 serves to raise the internal temperature of the aluminum source reservoir 122 to a target temperature at which the aluminum source can be vaporized. A liquid reservoir 126 is provided for applying an indirect heating scheme by the heating means 124, and a liquid (eg, silicone oil) 128 between the aluminum source reservoir 122 and the liquid reservoir 126. It may be provided. The liquid 128 serves to uniformly heat the aluminum source reservoir 122. The aluminum source reservoir 122 is preferably coated with a material having chemical resistance, such as a Teflon material. In the case of using aluminum chloride (AlCl ₃ ) as the aluminum source, the chlorine (Cl) component is corroded to the metal, so it is preferable to prevent the aluminum source storage 122 from being corroded by coating with a Teflon material having chemical resistance. In order to facilitate the aluminum source gas supply from the aluminum source reservoir 122 to the reaction chamber 110, the aluminum source reservoir 122 may be in communication with the carrier gas supply 140 through a conduit. The carrier gas introduced from the carrier gas supply unit 140 into the aluminum source storage unit 122 serves to push the aluminum source gas into the reaction chamber 110, and the aluminum source gas is reacted with the aluminum source storage unit 122 and the reaction chamber. It does not stick to the wall of the conduit 129 provided between the (110). Heating means 129a and 129b are provided around the conduit 129 that communicates the aluminum source reservoir 122 and the reaction chamber 110 to maintain the temperature of the conduit 129 constant above a certain temperature. Do.

The nitrogen source supply unit 130 serves to supply a nitrogen source to the reaction chamber 110. The nitrogen source supply unit 130 may include a mass flow controller (MFC) 132 and a valve 134 for controlling a supply flow rate of the nitrogen source gas. The nitrogen source gas is supplied to the reaction chamber 110 through the control of the flow controller (MFC) 132 and the valve 134. In order to facilitate the nitrogen source gas supply from the nitrogen source supply 130 to the reaction chamber 110, the nitrogen source gas discharged from the nitrogen source supply 130 is carried by the carrier gas when flowing through the conduit 136. Can be. The carrier gas introduced from the carrier gas supply unit 140 into the conduit 136 serves to push the nitrogen source gas into the reaction chamber 110, and the nitrogen source gas is between the nitrogen source supply unit 130 and the reaction chamber 110. It does not stick to the wall of the provided conduit 136.

The carrier gas supply unit 140 serves to supply the carrier gas to the aluminum source supply unit 120, the conduit 136, and the reaction chamber 110. The carrier gas supply unit 140 may include a flow controller (MFC) 142a, 142b, and 142c and valves 144a, 144b, and 144c for controlling a supply flow rate of the carrier gas. The carrier gas is supplied through the control of the flow controllers 142a, 142b, and 142c and the valves 144a, 144b, and 144c.

The collector 150 collects aluminum nitride (AlN) powder synthesized in the reaction chamber 110. The collector 150 is formed of a cylindrical primary collector 152 made of a material having excellent heat resistance and chemical resistance, such as stainless steel (SUS), and aluminum nitride (AlN) that is not captured by the primary collector 152. Secondary collector 154 for filtering. A cooling cylinder is provided around the primary collecting unit 152, and the primary collecting unit 152 is water cooled by cooling water (CW) flowing in the cooling cylinder to collect aluminum nitride (AlN) powder. It adheres to the wall of the part 152 to be collected. Cooling water inlet (CWI) is connected to the cooling cylinder to supply the cooling water, and the supplied cooling water is discharged through the cooling water outlet (CWO), and the cooling water is circulated through the cooling cylinder to the primary Collector 152 is to be cooled evenly throughout. The secondary collector 154 is configured as a filter for filtering out fine aluminum nitride (AlN) powder that has passed through the primary collector 152. The filter is preferably made of a material having excellent chemical resistance, such as a filter made of Teflon or a filter coated with Teflon. The primary collecting unit 152 and the secondary collecting unit 154 also collect reaction by-products (eg, NH ₄ Cl) together with aluminum nitride (AlN) powder. Since the reaction by-product (eg, NH ₄ Cl) is also collected in the secondary collecting unit 154, aluminum nitride (AlN) powder may be collected even if the pore size of the filter is larger than the particle size of the aluminum nitride (AlN) powder. For example, even if the collected aluminum nitride (AlN) powder has a size of 100 nm or less, the aluminum nitride (AlN) powder can be sufficiently collected even if the pore size of the filter is about 0.2 μm (200 nm).

The pumping unit 160 may vacuum the reaction chamber 110, the aluminum source reservoir 122, and the collector 150, and discharge the aluminum nitride (AlN) synthesized in the reaction chamber 110 to the collector 150. Induce. Pumping unit 160 is a rotary pump (162) for making a vacuum state, the gas discharged from the reaction chamber 110, aluminum source reservoir 122 and collector 150 to the outside to the outside Outlet 164 and valves 166a and 166b for blocking or regulating the exhaust of gas by pump 162.

Hereinafter, a method of manufacturing aluminum nitride (AlN) powder using the chemical vapor synthesis apparatus 100 will be described.

Charge the aluminum source into the aluminum source reservoir 122, open the valves 166a and 166b with the valves 134, 144a, 144b and 144c closed and open the aluminum source reservoir 122, the reaction chamber 110 and In order to remove the impurity gas present in the collector 150 and to create a vacuum state, the rotary pump 162 is operated to evacuate until it reaches a vacuum state (for example, about -100 KPa (-1000 mbar or less)). At this time, by supplying power to the heating means 116 surrounding the circumference of the reaction chamber 110 to heat the reaction chamber 110 it is possible to efficiently exhaust the impurity gas remaining in the reaction chamber 110.

After closing the valve 166b, the valves 144a, 144b and 144c are opened and the carrier gas is injected through the flow controllers 142a, 142b and 142c. The supply flow rate of the carrier gas is preferably about 100 to 500 ml / min. As a carrier gas, an inert gas such as nitrogen (N ₂ ) gas or argon (Ar) may be used, but it is preferable to use nitrogen (N ₂ ) gas, which may also act as a nitrogen source. In addition, the carrier gas may contain about 1 to 3% of hydrogen (H ₂ ) gas, which is oxygen (O ₂ ) remaining in the conduits 129 and 136 and the reaction chamber 110 of the chemical vapor synthesis apparatus 100. To remove it. By the introduction of the carrier gas, the aluminum source reservoir 122, the conduits 129 and 136, the reaction chamber 110, the collector 150, and the like are sufficiently filled with the carrier gas.

After opening the valve 166b and reducing the pumping amount of the rotary pump 162, it is kept constant so that the amount of the exhaust gas is kept uniform. As a result, the internal pressure of the reaction chamber 110 is also kept constant, and the aluminum nitride (AlN) powder synthesized in the reaction chamber 110 by the continuous operation of the rotary pump 162 is collected in the reaction chamber 110 and the collector ( 150 can be efficiently guided to the collector 150 without sticking to the wall of the conduit provided between. It is preferable to set the pumping amount of the rotary pump 162 so that the gas pressure discharged to the gas outlet 164 by the rotary pump 162 becomes about -100 mbar in consideration of the speed at which aluminum nitride (AlN) powder is collected. . If the gas pressure discharged to the gas outlet 164 is too small, aluminum nitride (AlN) powder may stick to the wall of the conduit provided between the reaction chamber 110 and the collector 150, so that the collector 150 If it cannot collect efficiently, and the gas pressure discharged to the gas outlet 164 is too large, it will only affect the synthesis of aluminum nitride (AlN) powder in the reaction chamber 110 or the yield collected from the primary collecting unit 152. There may be a problem with this falling.

The heating unit 124 is heated to vaporize the aluminum source charged in the aluminum source storage unit 122. As the aluminum source, AlCl ₃ containing aluminum (Al) may be used. As the aluminum source, it is preferable to use a material of high purity (eg, purity of 98% or more), and the particle size is not particularly limited, but aluminum chloride (AlCl ₃ ) of 2 to ₃ mm was used in the embodiment of the present invention. The vaporized aluminum source gas is introduced into the reaction chamber 110 through the conduit 129. At this time, the carrier gas introduced into the aluminum source storage unit 122 through the valve 144c of the carrier gas supply unit 140 serves to push the aluminum source gas into the reaction chamber 110 and the aluminum source gas stores the aluminum source. It does not stick to the wall of the conduit 129 provided between the portion 122 and the reaction chamber 110. The heating by the heating means 124 is preferably applied an indirect heating method, it is preferable that the temperature of the aluminum source storage 122 is maintained at about 100 ~ 280 ℃ considering the sublimation temperature of the aluminum source. The indirect heating method has the effect of suppressing the sublimation of the aluminum source abruptly in the vicinity of the sublimation point so that the sublimation gradually occurs uniformly.

Opening the valve 134 while introducing the aluminum source gas into the reaction chamber 110 and injecting the nitrogen source gas into the reaction chamber 110 through the flow controller 132. As the nitrogen source, a gas containing a nitrogen component such as ammonia (NH ₃ ) and nitrogen (N ₂ ) may be used. The carrier gas introduced from the carrier gas supply unit 140 into the conduit 136 serves to push the nitrogen source gas into the reaction chamber 110, and the nitrogen source gas is between the nitrogen source supply unit 130 and the reaction chamber 110. Do not stick to the wall of the provided conduit 136 to be smoothly transported to the reaction chamber (110).

It is preferable that the reaction chamber 110 is heated by the heating means 116 to maintain a constant temperature before the aluminum source gas and the nitrogen source gas are introduced. The internal temperature of the reaction chamber 110 heated by the heating means 116 is kept constant at a temperature (eg, 800-1400 ° C.) at which the aluminum source and the nitrogen source can react and synthesize.

The aluminum source gas and the nitrogen source gas introduced into the reaction chamber 110 are chemically reacted to form aluminum nitride (AlN) powder. The reaction scheme of the production of aluminum nitride (AlN) powder by chemical vapor phase synthesis according to a preferred embodiment of the present invention is shown in Scheme 1.

Scheme 1 below is a case where aluminum chloride (AlCl ₃ ) is used as a source of aluminum (Al), and a case where ammonia (NH ₃ ) is used as a nitrogen source.

AlCl ₃ (g) + 4 NH ₃ (g) ↔ AlN (s) + 3NH ₄ Cl (s)

When the aluminum source gas and the nitrogen source gas flow into the reaction chamber 110, the aluminum source gas and the nitrogen source gas are chemically vapor-phase reacted at a temperature of 800 to 1400 ° C., preferably at 900 to 1200 ° C. For example, aluminum chloride (AlCl ₃ ) gas, which is an aluminum source gas, and ammonia (NH ₃ ) gas are chemically reacted to form aluminum nitride (AlN) powder and ammonium chloride (NH ₄ Cl), which is a byproduct of reaction.

Aluminum nitride (AlN) powder and reaction by-products synthesized in the reaction chamber 110 are collected in the primary collector 152 of the collector 150. Since the primary collector 152 is water-cooled by the coolant flowing around the cylindrical primary collector 152, aluminum nitride (AlN) powder and reaction by-products are condensed and adhered to the wall of the primary collector 152 to be collected. do. Aluminum nitride (AlN) powder and reaction by-products not captured by the primary collector 152 are collected in the secondary collector 154 made of a Teflon filter.

Since the reaction by-products are also collected in the primary collector 152 and the secondary collector 154, it is necessary to filter out only aluminum nitride (AlN) powder. The reaction byproduct can be removed using methods such as pyrolysis. When using the pyrolysis method, it is required to pyrolyze at a temperature lower than the temperature at which aluminum nitride (AlN) is pyrolyzed (aluminum nitride powder having a thickness of 100 nm or less is pyrolyzed at about 600 ° C). For example, ammonium chloride (NH ₄ Cl) formed as a reaction byproduct has the property of pyrolyzing at a temperature of 386 ° C. or higher.

The aluminum nitride (AlN) powder and the reaction byproduct collected in the collector 150 are heat treated in a furnace (electric furnace) to selectively remove only the reaction byproduct. Pyrolysis of the reaction by-products can be carried out in a nitrogen or inert gas atmosphere for 30 minutes to 2 hours. Referring to the pyrolysis process of the reaction by-products, the aluminum nitride (AlN) powder and the reaction by-products collected by the collector 150 are loaded into a furnace, and the pyrolysis temperature 200 to target the temperature of the furnace is described. To 500 ° C.). At this time, the gas atmosphere of the furnace is set to nitrogen or an inert gas atmosphere. When the temperature of the furnace rises to the target heat treatment temperature, it is maintained at that temperature for a predetermined time and heat treated. The heat treatment is preferably carried out for 30 minutes to 2 hours. If the heat treatment time is too small, sufficient thermal decomposition of the reaction by-product is not achieved, and if the heat treatment time is too long, it takes a lot of time, which may result in uneconomical and agglomeration of aluminum nitride (AlN) powder particles. By the heat treatment, the reaction by-products are pyrolyzed to leave only aluminum nitride (AlN) powder. After performing the heat treatment process, the temperature of the furnace is lowered to unload aluminum nitride (AlN) powder.

The invention is described in more detail with reference to the following examples, which are not intended to limit the invention.

<Examples>

Charge aluminum chloride (AlCl ₃ ) into the aluminum source reservoir 122, open the valves 166a and 166b with the valves 134, 144a, 144b and 144c closed, and open the aluminum source reservoir 122 and the reaction chamber. The rotary pump 162 was operated to exhaust the impurity gas existing in the 110 and the collector 150 and to form a vacuum state, and the air was evacuated until it became about -100 KPa (-1000 mbar) or less. At this time, power was supplied to the heating means 116 surrounding the circumference of the reaction chamber 110 and the reaction chamber 110 was heated to exhaust the impurity gas remaining in the reaction chamber 110.

After closing the valve 166b, the valves 144a, 144b and 144c were opened and the carrier gas was injected through the flow controllers 142a, 142b and 142c. The supply flow rate of the carrier gas was set at about 500 ml / min. Nitrogen (N ₂ ) gas was used as the carrier gas, and hydrogen (H ₂ ) gas was also included at about 3%.

After opening the valve 166b and reducing the pumping amount of the rotary pump 162, it was kept constant so that the amount of the exhaust gas was kept uniform. The pumping amount of the rotary pump 162 was set such that the gas pressure discharged to the gas outlet 164 by the rotary pump 162 was about -100 mbar in consideration of the rate at which aluminum nitride (AlN) powder was collected.

The heating unit 124 was heated to vaporize the aluminum chloride (AlCl ₃ ) charged in the aluminum source reservoir 122. As aluminum chloride (AlCl ₃ ), a material having a purity of 98% having a particle diameter of 2-3 mm was used. Vaporized aluminum chloride (AlCl ₃ ) was introduced into the reaction chamber 110 through the conduit 129, at which time the carrier gas to the aluminum source reservoir 122 through the valve 144c of the carrier gas supply 140. Was allowed to flow. The heating by the heating means 124 is applied to the indirect heating method, the temperature of the aluminum source reservoir 122 is maintained at about 280 ℃, the heating means 129a, 129b provided around the conduit 129 As a result, the temperature of the conduit 129 was maintained at about 110 ° C.

While introducing the aluminum chloride (AlCl ₃ ) gas into the reaction chamber 110, the valve 134 was opened and ammonia (NH ₃ ) gas was injected into the reaction chamber 110 through the flow controller 132. At this time, the carrier gas was introduced from the carrier gas supply unit 140 into the conduit 136 so as not to stick to the wall of the conduit 136 provided between the nitrogen source supply unit 130 and the reaction chamber 110.

Before the aluminum chloride (AlCl ₃ ) gas and the ammonia (NH ₃ ) gas were introduced, the reaction chamber 110 was heated by the heating means 116 to maintain a temperature of about 1200 ° C.

In the reaction chamber 110, aluminum chloride (AlCl ₃ ) gas and ammonia (NH ₃ ) gas were chemically reacted to form aluminum nitride (AlN) powder.

Aluminum nitride (AlN) powder and ammonium chloride (NH ₄ Cl) synthesized in the reaction chamber 110 were collected in the primary collector 152 and the secondary collector 154 of the collector 150. The primary collecting unit 152 was to cool the water to circulate the cooling cylinder as a whole, and the secondary collecting unit 154 used a filter made of Teflon material having a pore size of 0.2㎛.

2A to 2D are field emission scanning electron microscopes showing the appearance of aluminum nitride (AlN) powder and ammonium chloride (NH ₄ Cl) collected from the primary collecting unit 152 and the secondary collecting unit 154. Scanning Electron Microscope (hereinafter referred to as FE-SEM). FIG. 3 shows X-ray diffraction (hereinafter referred to as 'XRD') for aluminum nitride (AlN) powder and ammonium chloride (NH ₄ Cl) collected from the primary collector 152 and the secondary collector 154. ') Graph. In FIG. 3, the peak appearing at a position of about 32 in 2θ is due to ammonium chloride (NH ₄ Cl) and the circular shape is due to aluminum nitride (AlN) powder. It can be seen that a powder having a relatively constant size was formed as shown in FIGS. 2A to 2D and FIG. 3.

Distilled water was washed to remove ammonium chloride (NH ₄ Cl) as a byproduct. Ammonium chloride (NH ₄ Cl) takes advantage of the ability to dissolve well in water. 4A and 4B are FE-SEM photographs after washing aluminum nitride (AlN) powder and ammonium chloride (NH ₄ Cl) collected in the collector 150 with distilled water. 5 is an XRD graph after washing aluminum nitride (AlN) powder and ammonium chloride (NH ₄ Cl) collected in the collector 150 with distilled water. After washing with distilled water, ammonium chloride (NH ₄ Cl) is removed, but aluminum nitride (AlN) reacts with water to change to AlOOH, so it was concluded that the method by washing with distilled water is not preferable.

Therefore, a heat treatment method was used to remove the reaction by-product ammonium chloride (NH ₄ Cl). Aluminum nitride (AlN) powder and ammonium chloride (NH ₄ Cl) collected in the collector 150 was heat-treated in an electric furnace to selectively remove only ammonium chloride (NH ₄ Cl).

Pyrolysis of ammonium chloride (NH ₄ Cl) was carried out for 30 minutes at a temperature of 400 ℃ in a nitrogen (N ₂ ) gas atmosphere. 6A and 6B are FE-SEM photographs after heat treatment of aluminum nitride (AlN) powder and ammonium chloride (NH ₄ Cl) collected in the collector 150 at a temperature of 400 ° C. for 30 minutes. FIG. 7 is an XRD graph of an aluminum nitride (AlN) powder and ammonium chloride (NH ₄ Cl) collected in the collector 150 after heat treatment at a temperature of 400 ° C. for 30 minutes. As shown in FIGS. 6A and 6B, the aluminum nitride (AlN) powder has a particle size of 100 nm or less and has a size of about 10 to 80 nm. As shown in FIGS. 6A, 6B and 7, it was confirmed that ammonium chloride (NH ₄ Cl) remained slightly after the heat treatment.

Therefore, in order to completely remove the reaction by-product ammonium chloride (NH ₄ Cl) to selectively remove by performing pyrolysis in a nitrogen (N ₂ ) gas atmosphere at a temperature of 400 ℃ for 1 hour. 8 is an XRD graph of an aluminum nitride (AlN) powder and ammonium chloride (NH ₄ Cl) collected in the collector 150 after heat treatment at a temperature of 400 ° C. for 1 hour. 9A and 9B are heat treatment of the aluminum nitride (AlN) powder and ammonium chloride (NH ₄ Cl) collected by the collector 150 at a temperature of 400 ℃ for 1 hour to selectively remove ammonium chloride (NH ₄ Cl) after Transmission Electron Micorscope (TEM) images. As shown in FIGS. 8, 9A, and 9B, ammonium chloride (NH ₄ Cl) is completely removed, indicating that only aluminum nitride (AlN) powder is present. In addition, as shown in FIGS. 9A and 9B, the aluminum nitride (AlN) powder has a particle size of 100 nm or less and has a size of about 10 to 80 nm.

As mentioned above, although preferred embodiment of this invention was described in detail, this invention is not limited to the said embodiment, A various deformation | transformation by a person of ordinary skill in the art within the scope of the technical idea of this invention is carried out. This is possible.

1 is a view for explaining a chemical vapor synthesis apparatus according to a preferred embodiment of the present invention.

2a to 2d are field emission scanning electron microscope (FE-SEM) images showing the appearance of aluminum nitride powder and ammonium chloride collected from the primary and secondary collectors.

FIG. 3 is an X-ray diffraction (XRD) graph of aluminum nitride powder and ammonium chloride collected at the primary and secondary collectors.

4A and 4B are FE-SEM photographs after washing aluminum nitride powder and ammonium chloride collected in a collector with distilled water.

5 is an XRD graph after washing aluminum nitride powder and ammonium chloride collected in a collector with distilled water.

6A and 6B are FE-SEM photographs after heat treatment of aluminum nitride powder and ammonium chloride collected in a collector for 30 minutes at a temperature of 400 ° C.

7 is an XRD graph after heat treatment of aluminum nitride powder and ammonium chloride collected in a collector for 30 minutes at a temperature of 400 ℃.

8 is an XRD graph of the aluminum nitride powder collected in the collector and ammonium chloride after heat treatment at 400 ° C. for 1 hour.

9A and 9B are transmission electron microscope (TEM) photographs after the aluminum nitride powder collected in the collector and ammonium chloride were heat treated at a temperature of 400 ° C. for 1 hour to selectively remove ammonium chloride.

<Explanation of symbols for the main parts of the drawings>

100: chemical vapor synthesis apparatus 110: reaction chamber

120: aluminum source supply unit 130: nitrogen source supply unit

140: carrier gas supply unit 150: collector

160: pumping unit

Claims (14)

(a) heating the reaction chamber by heating means to keep it constant at a temperature of 800-1400 ° C; (b) heating using heating means to vaporize the aluminum source charged into the aluminum source reservoir; (c) injecting a nitrogen source gas into the reaction chamber while introducing a vaporized aluminum source gas into the reaction chamber; (d) forming aluminum nitride powder by chemical vapor phase reaction between the aluminum source gas and the nitrogen source gas in the reaction chamber; (e) collecting aluminum nitride powder and reaction by-products synthesized in the reaction chamber in a collector; And (f) selectively removing the reaction by-products by heat treatment at a temperature higher than the temperature at which the reaction by-products are pyrolyzed and below the temperature at which aluminum nitride is pyrolyzed to remove the collected reaction by-products, In the step (e), The collector includes a primary collector and a secondary collector, wherein the cooling water is circulated in the cooling cylinder provided around the primary collector to condense aluminum nitride and reaction by-products to condense the primary collector of stainless material. And collecting aluminum nitride powder and reaction by-products passing through the primary collecting portion by using a filter made of Teflon having chemical resistance and heat resistance as the secondary collecting portion. . According to claim 1, Before the step (a), Operating a rotary pump and evacuating to a vacuum state in order to remove an impurity gas existing in the aluminum source storage unit, the reaction chamber and the collector in which the aluminum source is stored, and to create a vacuum state; Injecting a carrier gas into the reaction chamber; And A method for producing aluminum nitride powder, the method comprising: maintaining a uniform amount of exhaust gas after reducing the pumping amount of the pumping unit. The method of claim 1, wherein a carrier gas is supplied to the reaction chamber and the aluminum source storage unit, nitrogen or an inert gas is used as the carrier gas, and a supply flow rate of the carrier gas is set to about 100 to 500 ml / min. Method for producing aluminum nitride powder, characterized in that. The method of claim 3, wherein the carrier gas further contains 1 to 3% hydrogen gas to remove residual oxygen present in the reaction chamber or the aluminum source storage. According to claim 1, wherein step (b), The heating by means of the heating means to vaporize the aluminum source charged into the aluminum source storage unit, the heating by the heating means is applied by the heating means by applying an indirect heating method and the temperature of the aluminum source storage unit is maintained at 100 ~ 280 ℃ And the conduit between the aluminum source reservoir and the reaction chamber is maintained above a certain temperature by means of heating means. delete The method of claim 1, wherein the pyrolysis of the reaction by-product is performed for 30 minutes to 2 hours at a temperature of 200 to 500 ° C. in a nitrogen or inert gas atmosphere. 2. The aluminum nitride of claim 1, wherein AlCl ₃ including aluminum (Al) is used as the aluminum source, and ammonia (NH ₃ ) and nitrogen (N ₂ ) are used as the nitrogen source. Method for preparing the powder. The method of claim 1, wherein the aluminum source is used aluminum chloride (AlCl ₃ ), the nitrogen source is ammonia (NH ₃ ), the aluminum chloride (AlCl ₃ ) gas and ammonia (NH) in the reaction chamber _{3) the} ammonium chloride gas is an aluminum nitride (AlN) powder and the reaction by-products by the reaction chemical vapor (NH ₄ Cl) are synthesized, and the ammonium chloride (NH ₄ Cl), ammonium chloride (NH ₄ Cl at a temperature above the thermal decomposition temperature of ) Is selectively removed. The method for producing aluminum nitride powder according to claim 1, wherein the formed aluminum nitride powder has a particle diameter of 10 to 80 nm. A reaction chamber in which an aluminum source and a nitrogen source are chemically reacted to synthesize aluminum nitride powder; An aluminum source supply unit supplying an aluminum source gas to the reaction chamber; A nitrogen source supply unit supplying a nitrogen source gas to the reaction chamber; A carrier gas supply unit configured to transport aluminum source gas and nitrogen source gas to the reaction chamber; A collector for collecting the aluminum nitride synthesized in the reaction chamber; And A pumping part configured to vacuum the reaction chamber and the collector and direct the aluminum nitride (AlN) powder synthesized in the reaction chamber to flow into the collector; The aluminum source supply unit, An aluminum source storage unit for storing an aluminum source and supplying an aluminum source gas to the reaction chamber, a heating means for heating and vaporizing the aluminum source, a liquid storage unit for applying an indirect heating method, and the aluminum source storage unit And a liquid for uniformly heating the aluminum source reservoir between the liquid reservoir and The collector, A cylindrical first collector of stainless steel having heat resistance and chemical resistance; And A secondary collector for filtering aluminum nitride powder and reaction by-products not captured in the primary collector, A cooling cylinder is provided around the primary collecting unit, and the inside of the cooling cylinder is configured to allow the cooling water to be purified so that the aluminum nitride powder and the reaction by-product are condensed and adhered to the wall of the primary collecting unit to collect the secondary collecting unit. A chemical vapor synthesis apparatus for producing an aluminum nitride powder, comprising a filter for filtering out aluminum nitride powder and a reaction by-product passing through a primary collection unit. 12. The method of claim 11, wherein the aluminum source reservoir is coated with a Teflon material having a heat resistance and chemical resistance, and communicates with the carrier gas supply portion and the conduit for introducing a carrier gas, the aluminum source reservoir and the reaction chamber A chemical vapor synthesis apparatus for producing aluminum nitride powder, characterized in that a heating means is provided around the conduit to communicate with. The chemical vapor phase synthesizing apparatus for forming aluminum nitride powder according to claim 11, wherein the reaction chamber is made of quartz having thermal shock resistance, and a heating means is provided around the reaction chamber. delete

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