JPH05221618A - Production of aluminum nitride powder - Google Patents

Abstract

PURPOSE:To enable the low-temperature synthesis of aluminum nitride, to prevent the evaporation of a sintering assistant component and to improve the controllability of the particle shape and size and, consequently, to obtain an easily sinterable aluminum nitride powder in high reproducibility at a low cost. CONSTITUTION:A powdery mixture composed of aluminum oxide powder, carbon powder and at least one kind of compound powder selected from alkaline earth metal compound and rare earth element compound is used as a starting raw material and subjected to reduction nitriding reaction of Al2O3-C-N2 system. The above compound powder is selected to have the minimum eutectic temperature with Al2O3 of <=1450 deg.C for alkaline earth metal compound and <=1780 deg.C for rare earth element compound. The amount of the compound powder is 0.5-15 pts.wt. based on 100 pts.wt. of the sum of the aluminum oxide powder and the carbon powder and the powdery mixture is baked in a nitrogen- containing non-oxidizing atmosphere at 1000-1500 deg.C. An aluminate is synthesized during the reaction and the aluminate is reduced and nitrided to form the aluminum nitride powder.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing aluminum nitride powder by a reduction nitriding method, and more particularly to a method for producing aluminum nitride powder exhibiting easy sinterability.

[0002]

2. Description of the Related Art Aluminum nitride (AlN) is a non-oxide ceramic characterized by excellent thermal conductivity and electrical insulation, and is expected to be applied to substrates such as ICs and LSIs and packages. It is a new ceramic material that has started to be used. Further, since it has excellent corrosion resistance, it has been found that it can be used in some highly corrosive environments.

However, aluminum nitride is a substance having a strong covalent bond and no melting point, and is 2200 ° C. to 2 ° C. under 1 atm.
Since it decomposes at 400 ℃, it is positioned as a non-sinterable substance. For this reason, it is usually possible to use a high-purity fine powder and a finely sintered powder using a raw material powder in which an alkaline earth metal compound such as yttria or calcia or a rare earth element compound is mixed as a sintering aid. Has been done. Further, when the above-mentioned sintering aid is used, the aid captures the impurity oxygen in the aluminum nitride, so that the effect of easily achieving high thermal conductivity is also obtained.

In producing an aluminum nitride sintered body,
The importance of controlling the characteristics of the raw material powder is clear from the above-mentioned mechanism of high thermal conductivity, and various studies have been conducted. Based on such a fact, the raw material powder of aluminum nitride includes, for example, (a) high purity and fine powder,
(b) Oxygen impurities are controlled to be small, (c) Particle size distribution is narrow, and its shape is equiaxed, (d) Easy sinterability, (e) Excellent economical efficiency , (F) Excellent reproducibility is required.

By the way, there are three known methods for synthesizing aluminum nitride powder: a direct nitriding method of aluminum, a reductive nitriding method of alumina, and a vapor phase reaction method of organic aluminum and ammonia. Has been done. Among these, and the method is industrially used, and although the method in terms of cost is the most preferable, it is inferior to the method in terms of quality such as particle diameter and particle shape.
Moreover, although the method of (1) satisfies a considerable part of the above-mentioned required characteristics and is expected as a synthesis method for obtaining fine ceramics, it is compared with alumina (Al ₂ O ₃ ) which is an existing substrate and package material. I have to say that the cost is insufficient. That is, it has been difficult to reduce the dispersion of the particle size after finely pulverizing it and to make the particle shape into a spherical shape that is advantageous for sintering.

On the other hand, the characteristics of the aluminum nitride sintered body are as follows.
It also depends on the dispersion state of the sintering aid that is added to and mixed with the aluminum nitride powder. Usually, the raw material powder of the aluminum nitride sintered body is produced by mixing the aluminum nitride powder and the sintering aid powder with a ball mill or the like.
Since the powders are mixed together, it takes a long time to obtain a homogeneous mixed state, and the ideal mixed state cannot be obtained even if the mixing operation is continued for a long time, which causes various problems. It was

Therefore, when synthesizing aluminum nitride by the reduction nitriding method, a method of producing aluminum nitride powder in a state in which the sintering aid component is already contained is disclosed in, for example, JP-A-60-65768. No. 61-155209. In any of the methods described in these, alumina powder, carbon powder and a compound powder of an alkaline earth element or a rare earth element, which function as a sintering aid, are simply mixed, and the sintering aid is optionally mixed after the synthesis of aluminum nitride. The agent component is intended to remain. Further, in any of the above methods, the synthesis temperature is set to 1400 ° C. or higher from the viewpoint of reactivity, and specifically, the synthesis is performed at a high temperature of about 1550 ° C. to 1800 ° C. However, if the firing is performed at a high temperature such as 1550 ° C. or higher, the compound of the alkaline earth element or the rare earth element is easily volatilized in the firing process, and it becomes difficult to sufficiently leave the sintering additive component after the synthesis. Had a problem. In addition, adding a large amount of the sintering aid component in advance leaves a quantitatively unnecessary additive after the reduction nitriding reaction of the Al ₂ O ₃ —CN ₂ system, so that the yield of aluminum nitride is reduced. Will lower it. Further, the high temperature firing is economically disadvantageous, and since the growth of crystal grains is likely to occur, there arises a problem that it is difficult to control the grain shape and grain size.

[0008]

As described above, in the conventional method for producing aluminum nitride by the reduction nitriding method, in order to obtain the easily sinterable aluminum nitride powder, the sintering aid component is added from the synthesis stage. Although it has been attempted to add it in advance, since it was said that firing at a high temperature such as 1550 ° C. or higher was required, it caused volatilization and grain growth of the sintering additive component, and a sufficient effect was obtained. It wasn't done.

From the above, it is strongly required to enable the low temperature synthesis of the aluminum nitride powder in order to obtain the aluminum nitride powder containing the sintering aid component and having the controlled particle shape and particle size. It was being done.

The present invention has been made to solve the above problems, and enables low-temperature synthesis of aluminum nitride, prevents volatilization of the sintering aid component as much as possible, and controls the particle shape and particle size. It is an object of the present invention to provide a method for producing an aluminum nitride powder, which makes it possible to obtain an easily sinterable aluminum nitride powder economically and with good reproducibility.

[0011]

The first method for producing an aluminum nitride powder according to the present invention comprises an aluminum oxide powder, a carbon powder, and at least one compound selected from an alkaline earth metal compound and a rare earth element compound. Using a mixed powder with a powder as a starting material, in a method for producing an aluminum nitride powder based on a reductive nitriding reaction of an Al ₂ O ₃ —CN ₂ system, as the compound powder, a eutectic minimum temperature with Al ₂ O ₃ is an alkali. If the compound containing an earth metal is 1450 ° C. or lower, and if the compound is a rare earth element compound, the compound is 1780 ° C. or lower, and this compound powder is used for 100 parts by weight of the total amount of the aluminum oxide powder and the carbon powder. 0.5-1
The starting material was prepared by adding in the range of 5 parts by weight, and the starting material was heated to 1000 ° C to 15 ° C in a non-oxidizing atmosphere containing nitrogen.
It is characterized by firing at a temperature in the range of 00 ° C.

The second method for producing aluminum nitride powder is as follows: Al ₂ O ₃ -aAl ₂ O ₃ .bM _x X _y -C (where M is at least 1 selected from alkaline earth elements and rare earth elements). The seed element, M _x X _y, has a minimum eutectic temperature with Al ₂ O ₃ , 1450 ° C or lower for a compound containing an alkaline earth element as M, and 1780 ° C for a compound containing a rare earth element as M. The following compounds are shown, and a, b, x and y are natural numbers) are used as starting materials, and the starting materials are fired in a non-oxidizing atmosphere containing nitrogen.

The method for producing an aluminum nitride powder of the present invention is based on an Al ₂ O ₃ --CN ₂ system reductive nitriding reaction, and uses alumina powder and carbon powder as main raw materials. The mixing ratio of the alumina powder and the carbon powder is preferably such that the molar ratio of Al ₂ O ₃ / C is in the range of 0.25 to 0.33. If the value of Al ₂ O ₃ / C (molar ratio) is larger than 0.33, that is, if the amount of carbon is too small, the synthesis of aluminum nitride at a low temperature cannot be sufficiently promoted. Further, when the value of Al ₂ O ₃ / C (molar ratio) is smaller than 0.25, that is, when the carbon amount is excessively large, unnecessary carbon remains, which causes a decrease in the yield of aluminum nitride. Become.

As the alumina powder and the carbon powder, those having an average particle diameter of 1 μm or less are preferably used. If the average particle size exceeds 1 μm, the reaction rate at low temperature decreases, which is not preferable. The more preferable average particle diameter of the alumina powder is 0.2 μm or less, and the more preferable average particle diameter of the carbon powder is 0.1 μm or less. These average particle diameters are important for obtaining the intermediate product in the reaction step described later relatively easily. Further, the amount of impurities in the alumina powder and carbon powder needs to be 1% by weight or less as a metal element amount, and particularly preferably 0.2% by weight or less.

The starting material in the production method of the present invention is obtained by adding and mixing at least one compound powder selected from an alkaline earth metal compound and a rare earth element compound to the above mixed powder of alumina and carbon, Alternatively, a composite compound (aluminate) of alumina and a compound containing at least one element selected from alkaline earth elements and rare earth elements is added and mixed. Then, such a starting material is put in a predetermined container, fired at a temperature in the range of 1000 ° C to 1500 ° C in a non-oxidizing atmosphere containing nitrogen, and further heat-treated in an oxidizing atmosphere to oxidize residual carbon. Remove to produce the desired aluminum nitride powder.

Here, the compound containing an alkaline earth element or a rare earth element is a component which reacts with alumina before the reductive nitriding of alumina to form an aluminate and promotes the synthesis of aluminum nitride at a low temperature. In order to obtain such a reaction promoting effect, it is an essential requirement that the reactivity with alumina is excellent.

Therefore, in the present invention, the eutectic minimum temperature of a compound containing an alkaline earth element or a rare earth element to be used with Al ₂ O ₃ is defined as follows:
This makes it possible to obtain the above reaction promoting effect with good reproducibility.

(1) Alkaline earth metal compound: 1450 ° C. or lower (2) Alkaline earth metal compound + rare earth element compound: 145
0 ° C or less (3) Rare earth element compounds: 1780 ° C or less For compounds with a minimum eutectic temperature with Al ₂ O ₃ above the specified temperature, the catalytic action of the reductive nitriding reaction of the Al ₂ O ₃ -CN ₂ system is sufficient. Therefore, the reaction cannot be efficiently performed at a low temperature of 1500 ° C or lower. That is, by adding a compound satisfying the above conditions,
It enables synthesis at temperatures as low as 00 ° C or less. The reason for setting the specified temperature of the rare earth element compound higher than that of the compound containing an alkaline earth element is that the reaction mechanism is not clear, but as in the case of being used as a sintering aid, A favorable result is obtained under this selection condition.

Compounds satisfying the above conditions include CaO (eutectic minimum temperature with Al ₂ O ₃ : 1390 ° C.), B
Oxides of alkaline earth elements such as aO (at 1425 ℃), CaF ₂
Fluoride of alkaline earth elements such as (1395 ℃), CaO-CaF
₂ (at 1200 ℃ to 1400 ℃), CaO-Fe ₂ O ₃ (at 1200 ℃) and other complex compounds containing alkaline earth elements, Y ₂ O ₃ (at 17 ℃)
60 ℃), Yb ₂ O ₃ (same 1750 ℃), Eu ₂ O ₃ (same 1630)
C.), Gd ₂ O ₃ (same 1750 ° C.), and other oxides of rare earth elements. Of these, fluorides of alkaline earth elements and rare earth elements are particularly suitable for the present invention because they form an active aluminate at a lower temperature. As a powder of a compound containing these alkaline earth elements and rare earth elements, an average particle size of 1 μm is used for the same reason as for alumina powder.
It is preferable to use those of m or less. A more preferable average particle size is 0.8 μm or less. Also, the amount of impurities is
The amount of metal element must be 1% by weight or less, particularly preferably 0.2% by weight or less.

In the method for producing an aluminum nitride powder of the present invention, as described above, the added compound containing an alkaline earth element or a rare earth element reacts with alumina before the reductive nitriding of alumina to form an aluminate. Since this aluminate compound is subjected to a reduction nitriding action by carbon and nitrogen, it becomes possible to proceed the reaction (synthesis reaction of AlN) at a low temperature of 1500 ° C. or less and at a high speed.

Further, the compound containing an alkaline earth element or a rare earth element in the present invention has a catalytic action for accelerating the synthetic reaction of aluminum nitride and, at the same time, after the firing, the alkaline earth element or the rare earth element is contained in the aluminum nitride powder. It is also possible to leave it in the form of an oxide or a multiple oxide, and it functions as a sintering aid.

The present invention enables the synthesis at a low temperature of 1500 ° C. or less by using the above-mentioned additive compound. In other words, since the low temperature firing is possible, the above-mentioned sintering aid is obtained. It is possible to allow the compound that functions as an agent to remain sufficiently in the aluminum nitride powder. In the present invention, 50% by weight or more of the metal element added with the above compound can remain.
In consideration of such purpose, the set temperature during firing is extremely important, and if the firing temperature exceeds 1500 ° C, the alkaline earth elements and rare earth elements in the added compound will evaporate during firing and the sintering aid It becomes impossible to leave the required amount of the compound as an agent. A more preferable baking temperature is 1450 ° C or lower, and further preferably less than 1400 ° C.

The additive compound in the present invention is added in the range of 0.5 to 15 parts by weight based on 100 parts by weight of the total amount of alumina powder and carbon powder. Since the above-mentioned added compound has both the function of the reaction accelerator and the function of the sintering aid,
If the amount added is less than 0.5 parts by weight, the effect of promoting synthesis cannot be sufficiently obtained, and the aluminum nitride powder obtained cannot be sufficiently sinterable. Further, even if it is added in an amount of more than 15 parts by weight, not only the above effect cannot be obtained, but also it remains as an excessive amount, resulting in a decrease in the yield of the aluminum nitride powder. A more preferable addition amount is in the range of 3 to 10 parts by weight.

In the method for producing an aluminum nitride powder according to the present invention, the same effect as in the case of adding the above compound can be obtained by using an aluminate represented by aAl ₂ O ₃ .bM _x X _y as a starting material. Can be obtained. As M _x X _y in the aluminate, a compound similar to the compound containing an alkaline earth element or a rare earth element that satisfies the eutectic minimum temperature condition with alumina is used,
Specific examples thereof include composite compounds of the above-mentioned compounds and alumina.

The amount of aluminate added is M _x X _y /
The value of (Al ₂ O ₃ + M _x X _y ) is set so that the molar ratio is 10% or less. If the above molar ratio exceeds 10%, the yield of aluminum nitride powder will be reduced as in the case of the compound described above. In addition, since the addition amount of aluminate is too small to obtain a sufficient effect of promoting the synthesis reaction, the above molar ratio is preferably set to 1% or more. The above aluminate is preferably used as a powder having an average particle size of 5 μm or less.

By using such a starting material containing an aluminate, the reaction can be more efficiently performed at a low temperature of 1500 ° C. or less, and M _x X _y can be as much as 50% by weight or more in terms of metal element. It can remain. The conditions other than these are based on the case of adding the compound containing the alkaline earth element or the rare earth element described above. It should be noted that adding a compound of a rare earth element or an alkaline earth element separately shown in the present invention to this system also brings preferable results.

[0027]

OPERATION For example, calcium fluoride, which is one of the alkaline earth metal compounds, will be described as an example. Al ₂ O ₃ -C-CaF ₂
When the system is fired in a nitrogen gas stream under specified conditions, Al ₂ O
Before the reductive nitriding reaction of ₃ proceeds, Al ₂ O ₃ reacts with CaF ₂ to produce, for example, CaF ₂ · 5Al ₂ O ₃ (Al ₂ O _{3
O 3 + CaF 2 = CaF 2} · 5Al 2 O 3). This CaF ₂・ 5Al ₂ O
_{Since 3} has a melting point of 1395 ° C and is more reactive than Al ₂ O ₃ , the reductive nitriding reaction proceeds even at a low temperature of 1500 ° C or less (CaF ₂ · 5Al ₂ O ₃ + C + N ₂ = AlN + Ca compound + CO), aluminum nitride powder is efficiently synthesized.

Further, since the firing is carried out at a low temperature of 1500 ° C. or lower, additives such as CaF ₂ do not evaporate and repeat the circulation reaction, and finally in the form of oxides or complex oxides in the aluminum nitride powder. Remains in. Since the remaining oxides and complex oxides function as a sintering aid, the obtained aluminum nitride powder can be densified and sintered without adding a new sintering aid. Further, since aluminum nitride is efficiently synthesized by low-temperature firing, aluminum nitride powder having a uniform particle shape and particle size can be obtained without causing crystal grain growth. In addition, the obtained aluminum nitride powder has a spherical shape with high sinterability. Spherical powder
The filling rate at the time of producing a sintered body can be improved, and thus densification and sintering can be facilitated.

Even when an aluminate is used,
Similar effects are obtained. Explaining calcium fluoride aluminate as an example, based on the reaction shown below,
It becomes possible to manufacture aluminum nitride powder at low temperatures.

CaF ₂ .5Al ₂ O ₃ = AlN + Ca compound + CO Al ₂ O ₃ + Ca compound = (for example) CaF ₂ .5Al ₂ O ₃

[0031]

EXAMPLES Examples of the present invention will be described below.

Example 1 Alumina powder having an average particle size of 0.2 μm and an average particle size of 0.02
With μm carbon black, Al ₂ O ₃ / C (molar ratio) = 0.
Prepare 200 g of a mixture of 29 and add it to the average particle size.
3% by weight of 0.8 μm calcium fluoride powder (in all powders)
Was added. The powder containing this CaF ₂ was mixed for 20 hours with a ball mill using ethanol as a dispersion medium.

The mixed powder (starting raw material) thus prepared was placed in a carbon container and heated at a temperature of 500 cc / min while flowing nitrogen gas to be fired. Firing conditions are from room temperature to 10
The temperature rising rate up to 00 ° C was 500 ° C / hr, the temperature rising from 1000 ° C to 1350 ° C was 250 ° C / hr, and the temperature was maintained at 1350 ° C for a predetermined time. 1350
The holding time at ℃ was 1 hour and 2 hours, respectively. Further, these were heat-treated in air at 700 ° C. for 4 hours to oxidize and remove residual carbon, and collect the product.

The conversion rate of the reaction product thus obtained into AlN was calculated. As a result, 45% was reacted with 1 hour of calcination and 100% was reacted with 2 hours of calcination.
It was confirmed that Al ₂ O ₃ can be efficiently converted to AlN. This value is 0.2 when the average particle size is 0.2 without calcium fluoride added.
When only alumina powder of μm and carbon black having an average particle size of 0.02 μm were mixed in a ratio of Al ₂ O ₃ / C (molar ratio) = 0.29 and fired under the same temperature condition (Comparative Example 1) However, from the fact that the reaction rate was only 5% after the firing for 2 hours, it can be seen that the added compound exhibited a very effective reaction promoting effect.

The reaction product obtained under the firing conditions of 1 hour and 2 hours was subjected to powder shape measurement and component analysis. The results were obtained by firing the reaction product (Comparative Example 2) in which the starting materials having the same compositions as those of Comparative Example 1 and Comparative Example 1 were fired under the conditions of 1500 ° C. × 2 hours, and the starting material having the same composition as Example 1. Table 1 shows the measurement results of the reaction product (Comparative Example 3) obtained by firing the raw material under the conditions of 1550 ° C. × 2 hours.

[0036]

[Table 1] As is clear from Table 1, it is recognized that the additive remains in the aluminum nitride powder obtained in Example 1, while the additive is added when firing at 1550 ° C.
The Ca component evaporates and hardly remains, and as a result, the reaction is delayed and the grain growth proceeds. Further, the aluminum nitride powder calcined at 1500 ° C. without adding a compound of an alkaline earth element etc. was inferior in filling property in view of particle shape.

In addition, in Example 1 above, the states of the reaction product at the stage of holding at 1350 ° C. for 30 minutes and the reaction product after holding for 2 hours were observed by a scanning electron microscope. Aluminate formation was observed at the stage of holding at 1350 ° C for 30 minutes, and no aluminate was seen after holding for 2 hours, and almost spherical aluminum nitride powder was produced with a uniform particle size.

Example 2 Alumina powder having an average particle size of 0.2 μm and an average particle size of 0.02
With μm carbon black, Al ₂ O ₃ / C (molar ratio) = 0.
Prepare 200 g of a mixture of 29 and add it to the average particle size.
1.0 μm of yttrium oxide powder was added so as to be 3% by weight (of all powders). The powder containing Y ₂ O ₃ was mixed with ethanol as a dispersion medium in a ball mill for 20 hours.

The mixed powder (starting material) thus prepared was placed in a carbon container and heated at a temperature of 500 cc / min while flowing nitrogen gas to be fired. Firing conditions are from room temperature to 10
The temperature rising rate up to 00 ° C was 500 ° C / hr, and the temperature rising from 1000 ° C to 1450 ° C was 250 ° C / hr, and the temperature was maintained at 1450 ° C for a predetermined time. 1450
The holding time at ℃ was 1 hour and 2 hours, respectively. Furthermore, these were heat-treated in air at 700 ° C. for 4 hours to oxidize and remove residual carbon, and collect the product.

When the conversion rate of the reaction product thus obtained into AlN was determined, it was found that 52% was reacted with 1 hour of calcination, and 100% was reacted with 2 hours of calcination. This value is obtained by adding yttrium oxide-free alumina powder with an average particle size of 0.2 μm and carbon black with an average particle size of 0.02 μm to Al ₂ O ₃ / C.
(Mole ratio) = 0.29 was used only, and when the mixture was fired under the same temperature condition (Comparative Example 4), the reaction rate was 60% after the firing for 1 hour. It can be seen that a very effective reaction promoting effect was exhibited. Also,
When the reaction products obtained by calcination for 1 hour and 2 hours were subjected to component analysis, it was confirmed that the additives remained sufficiently in all cases.

Examples 3 to 12 Aluminum nitride powders were produced according to the starting materials and the firing conditions whose compositions are shown in Table 1 in accordance with the above Examples 1 and 2. The properties of these were evaluated in the same manner as in Example 1. The results are also shown in Table 2.

[0042]

[Table 2] Example 13 A mixture of 90 parts by weight of alumina powder having an average particle size of 0.2 μm and 10 parts by weight of CaF ₂ .5Al ₂ O ₃ aluminate powder having an average particle size of 2 μm was prepared. Carbon black with an average particle size of 0.02 μm was added to Al ₂ O ₃ / C.
(Mole ratio) = 0.29. Powder (total amount 200 g) containing this aluminate powder was mixed with ethanol as a dispersion medium in a ball mill for 20 hours.

The mixed powder (starting raw material) thus prepared was placed in a carbon container and heated at a temperature of 500 cc / min while flowing nitrogen gas to be fired. Firing conditions are from room temperature to 10
The temperature rising rate up to 00 ° C. was 500 ° C./hr, that from 1000 ° C. to 1400 ° C. was 250 ° C./hr, and the temperature was maintained at 1400 ° C. for a predetermined time. 1400
The holding time at ℃ was 1 hour and 2 hours, respectively. Furthermore, these were heat-treated in air at 700 ° C. for 4 hours to oxidize and remove residual carbon, and collect the product.

When the conversion rate of the reaction product thus obtained into AlN was determined, 100% reaction was observed in both 1-hour firing and 2-hour firing. This value is only for the case where aluminate is not added and alumina powder with an average particle size of 0.2 μm and carbon black with an average particle size of 0.02 μm are mixed in a ratio of Al ₂ O ₃ / C (molar ratio) = 0.29. It was found that the additive compound showed an extremely effective reaction promoting effect, since the reaction rate was only 28% after baking for 2 hours when the composition was baked under the same temperature condition (Comparative Example 5). .. In addition, component analysis was performed on the reaction products obtained by firing for 1 hour and 2 hours, and it was confirmed that the additives remained in both cases.

Examples 14 to 16 According to the above-mentioned Example 13, aluminum nitride powders were prepared under the starting materials and firing conditions whose compositions are shown in Table 3. With respect to these, the characteristics were evaluated in the same manner as in Example 13. The results are also shown in Table 3.

[0046]

[Table 3]

[0047]

As described above, according to the method for producing aluminum nitride powder of the present invention, it is possible to synthesize aluminum nitride at a low temperature, so that the volatilization of alkaline earth elements and rare earth elements added during the synthesis can be minimized. It is possible to prevent this, and thus it is possible for the sintering aid component to remain. Further, since grain growth and the like are suppressed, the controllability of the particle shape and the particle size is improved, and in particular, the filling rate is high, and it is possible to stably obtain an aluminum nitride powder having a spherical shape or an approximate shape having excellent reliability. Is possible. Furthermore, the synthesis of aluminum nitride by low temperature firing also contributes to the improvement of economic efficiency. As described above, according to the present invention, it is possible to economically and reproducibly obtain an easily sinterable aluminum nitride powder capable of additive-free sintering.

[0048]

Claims (6)

[Claims] 1. An aluminum oxide powder, a carbon powder,
In a method for producing an aluminum nitride powder based on a reductive nitriding reaction of an Al ₂ O ₃ -CN ₂ system, which uses a mixed powder of at least one compound powder selected from an alkaline earth metal compound and a rare earth element compound as a starting material. As the compound powder, a compound having a eutectic minimum temperature with Al ₂ O _{3 of} 1450 ° C. or lower if it is a compound containing an alkaline earth metal, and a compound of 1780 ° C. or lower if it is a rare earth element compound is used. Is added in a range of 0.5 to 15 parts by weight with respect to 100 parts by weight of the total amount of the aluminum oxide powder and the carbon powder to prepare the starting material, and the starting material is added in a non-oxidizing atmosphere containing nitrogen. A method for producing an aluminum nitride powder, which comprises firing at a temperature in the range of 1000 ° C to 1500 ° C. 2. The method for producing an aluminum nitride powder according to claim 1, wherein an aluminate of the compound is synthesized as an intermediate product during the reduction nitriding reaction, and aluminum nitride is produced from the aluminate. And a method for producing an aluminum nitride powder. 3. The method for producing an aluminum nitride powder according to claim 1, wherein the aluminum oxide powder and the carbon powder are Al in a molar ratio.
_A method for producing an aluminum nitride powder, which comprises mixing so that the value of ₂ O ₃ / C is in the range of 0.25 to 0.33. 4. Al ₂ O ₃ − aAl ₂ O ₃ .bM _x X _y − C
(However, M is at least one element selected from alkaline earth elements and rare earth elements, and M _x X _y is Al ₂ O ₃
A compound having a minimum eutectic temperature of 1450 ° C or lower for a compound containing an alkaline earth element as M and 1780 ° C or lower for a compound containing a rare earth element as M, a,
(b, x and y are natural numbers) A starting material is a system, and the starting material is fired in a non-oxidizing atmosphere containing nitrogen. 5. The method for producing an aluminum nitride powder according to claim 4, wherein the firing is performed at a temperature in the range of 1000 ° C. to 1500 ° C. 6. The method for producing an aluminum nitride powder according to claim 4, wherein the Al ₂ O ₃ and aAl ₂ O ₃ .bM _x X _y are in a molar ratio of M.
_A method for producing an aluminum nitride powder, characterized in that mixing is performed so that a value of _x X _y / (Al ₂ O ₃ + M _x X _y ) is 10% or less.