JP2807429B2 - Aluminum nitride sintered body - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to an aluminum nitride
More specifically, it relates to an aluminum nitride sintered body that can be sintered at a low temperature, is dense, has good thermal conductivity, and has good adhesion to a conductor layer and good glass sealing properties. .

[0002]

2. Description of the Related Art In recent years, as semiconductor devices such as ICs and LSIs have become faster and more highly integrated, the required characteristics of circuit boards and semiconductor packages have become stricter. For example, in order to efficiently radiate heat generated from a semiconductor element, high thermal conductivity is required, and in order to minimize the risk of destruction of the semiconductor element due to thermal stress, the coefficient of thermal expansion of the semiconductor element is reduced. It is required to be close to that of

As a ceramic material as an insulating material for circuit boards and packages, alumina (Al ₂ O _{3) is used.}
O ₃ ) Ceramics have been commonly used so far. However, although alumina ceramics have higher thermal conductivity than conventional plastic and glass materials, the thermal conductivity is still insufficient at about 20 W / m K and the thermal expansion coefficient is 7 × 10 ^-6 / K Coefficient of thermal expansion of silicon and silicon
(4.5 × 10 ⁻⁶ / K), which is about twice as high, so it cannot be said that it has sufficient characteristics to cope with high integration and high speed of semiconductor devices.

For these reasons, aluminum nitride (AlN) sintered bodies have attracted attention in place of alumina ceramics.
Applications of multilayer circuit boards to insulating materials and the like have been studied in various fields. The AlN sintered body has a coefficient of thermal expansion of 4.0 × 10 ⁻⁶ / K, which is substantially equal to the coefficient of thermal expansion of silicon, and has a feature that the thermal stress of the semiconductor element can be sufficiently reduced. Further, since a thermal conductivity exceeding 100 W / m K has been obtained, it can sufficiently cope with an increase in the amount of heat generated by high integration and high speed of the semiconductor element.

In order to obtain a dense and highly thermally conductive AlN sintered body, a sintering aid for trapping oxygen in AlN crystal particles, for example, an alkaline earth metal compound or a rare earth compound, is added, and usually, a temperature of 1973 K is added. It is sintered at the above high temperature. However, such an AlN sintered body sintered at a high temperature has problems such as a decrease in mechanical strength as the crystal grains grow. Such a decrease in mechanical strength of the AlN sintered body is fatal when applied to a substrate or a package for mounting a semiconductor chip. Therefore, a reduction in the sintering temperature is required.

On the other hand, cost reduction is urgently needed in order to expand the use of AlN sintered bodies in the future, and as an attempt to reduce the sintering temperature, realization of an existing continuous furnace has been studied. I have. As a result of recent research and development, improvement of the AlN sintering aid has enabled the use of ultrafine AlN powder, etc.
It is becoming possible to lower the sintering temperature to temperatures around 1873K.

[0007] Sintering aids effective for lowering the sintering temperature include, for example, rare earth elements and alkalis described in JP-A-61-209959, JP-B-5-17190 and JP-A-62-153173. Halides of earth metal elements are described. Similarly, as a method for lowering the sintering temperature of the AlN sintered body, for example, JP-A-1-183469 describes a method of simultaneously adding a rare earth oxide and an alkaline earth metal oxide as a sintering aid. Have been.

[0008]

However, according to the conventional low-temperature sintering method of AlN sintered bodies described in the above-mentioned publications, AlN which is sufficiently dense at a temperature lower than 1973K and has a high thermal conductivity is used. No sintered body has been obtained. For example, the methods described in JP-A-61-209959 and JP-A-62-153173 cannot achieve a high thermal conductivity exceeding 100 W / mK at 1873K. In addition, 5
According to the method described in Japanese Patent No. -17190, a thermal conductivity of 120 W / m K is achieved, but all are obtained by firing at a temperature of 1973 K or higher. Furthermore, when a large amount of a halide of a rare earth element or an alkaline earth metal element is added, AlN
Many precipitates appear on the surface of the sintered body, causing not only uneven burning and uneven color, but also a decrease in surface smoothness. Many problems are involved.

Further, in the method described in Japanese Patent Application Laid-Open No. 1-183469, by adding Y ₂ O ₃ and CaO simultaneously, sintering at 1873 K for 8 hours gives a density of 3.27 g / cm ³ .
Although a thermal conductivity of 139 W / m K is achieved, it is considered that the sintered body is not completely pore-free and dense in view of the grain boundary phase components described.

On the other hand, when used as a circuit board or the like,
It is also necessary to consider the adhesion between the AlN insulating layer and the metal conductor layer. That is, when co-firing an AlN molded body with a metal conductor layer formed on the surface or inside at a high temperature,
If the adhesion between the metal conductor layer and the AlN insulating layer is not good, problems such as peeling of the conductor layer from the green layer after firing occur. When a multilayer circuit board obtained by baking is used as a package material, after mounting a semiconductor element, glass sealing using a cap may be performed to protect the element. Therefore, the glass sealing property needs to be good. However, it has not been possible to obtain a material that sufficiently satisfies all of the above mechanical strength, thermal conductivity, low-temperature sinterability, adhesion to conductors, and glass sealing properties with conventional AlN materials. .

As described above, it has been an issue for AlN sintered bodies to satisfy all of mechanical strength, thermal conductivity, low-temperature sinterability, adhesion to conductors, and glass sealing properties.

SUMMARY OF THE INVENTION The present invention has been made to address such problems, and can be sintered at a low temperature, has high mechanical strength and thermal conductivity, and has good adhesion to a conductor and glass sealing properties. An object of the present invention is to provide an excellent aluminum nitride sintered body.

[0013]

The aluminum nitride sintered body of the present invention contains aluminum nitride particles having an average particle diameter of 2 μm or less as a main component, and at least one selected from rare earth elements.
1 to 8% by weight in terms of oxides, 0.3 to 7% by weight in terms of oxides of at least one element selected from alkaline earth metal elements, and at least one element selected from Bi, Pb, Sb, In and Sn 5 to 25% by weight in terms of oxide.

The aluminum nitride sintered body of the present invention comprises:
At least one element selected from rare earth elements, and (2)
At least one element selected from alkaline earth metal elements and (3) at least one element selected from Bi, Pb, Sb, In and Sn at the same time, and each of these elements Each compound contained was added as a sintering aid. The simultaneous addition of the compounds (1) and (2) enables low-temperature sintering at 1973K or lower. Further, the addition of the compound (3) promotes sintering and densification at a low temperature, and improves the adhesion to the conductor layer and the glass sealing property.

The rare earth element of (1) includes Sc, Y and lanthanum series elements, and the added amount thereof is in the range of 1 to 8% by weight in terms of oxide. If the amount of the rare earth element compound is less than 1% by weight in terms of oxide, sinterability is insufficient,
Further, even if the sintering is sufficiently performed, the effect of trapping oxygen is reduced and the thermal conductivity is reduced. -If it exceeds 8% by weight,
The grain boundary phase generated inside the AlN sintered body becomes excessive, which causes a decrease in thermal conductivity. A more preferable addition amount is 1.5 to 7% by weight in terms of oxide.

As the alkaline earth metal element of (2), C
a, Ba, Sr, etc., and the amount of addition is 0.
It should be in the range of 3 to 7% by weight. If the amount of the alkaline earth metal element compound is less than 0.3% by weight in terms of oxide, the sinterability is insufficient, and even if the sintering is sufficient, the oxygen trapping effect is low, and high thermal conductivity cannot be achieved. On the other hand, if it exceeds 7% by weight, the grain boundary phase generated inside the AlN sintered body becomes excessive, which causes the thermal conductivity to decrease. In addition, the water resistance of an AlN sintered body in which a large amount of an alkaline earth metal compound is generated deteriorates. More preferable addition amount is 0.5 to 5
% By weight.

The element (3) selected from Bi, Pb, Sb, In and Sn has a low melting point of oxides and generates a liquid phase at a low temperature. This has the effect of facilitating arrangement and promoting sintering. Further, it has an effect of reacting with the oxide layer (Al ₂ O ₃ ) on the surface of the AlN grain to generate a eutectic liquid phase at a lower temperature, thereby promoting sintering.

Further, when the compound containing the element (3) is present, the adhesion between the conductor layer and the AlN insulating layer is improved when the conductor layer is formed at the same time or in a subsequent step. That is, as described above, the compound containing the element (3) generates a liquid phase at a low temperature, and this liquid phase has low viscosity and very good wettability. And solidifies after cooling, thereby firmly bonding the conductor layer and the AlN green layer. This improves the adhesion between the conductor layer and the AlN insulating layer.

The elements of (3) are all elements that can be contained in the glass. If these elements and Al and oxygen are simultaneously present on the surface of the sintered body, the glass of (3) is sealed by the element of (3). At the same time, the AlN sintered body and the sealing glass are firmly adhered to each other, and at the same time, the wetting angle of the glass to the AlN sintered body is reduced, so that good glass sealing is possible.

The amount of the compound containing the element (3) is in the range of 5 to 25% by weight in terms of oxide. If the amount is less than 5% by weight, the effect of promoting sintering becomes insufficient. Furthermore, compounds containing the element (3) generally have a high vapor pressure at high temperatures, so they are easily volatilized during the sintering process.If the amount is less than 5% by weight, a conductor layer co-fired, or a conductor prepared after sintering, The effect of improving the adhesion strength of the layer is reduced,
Further, the amount of the element (3) remaining in the AlN sintered body during glass sealing is reduced, and as a result, the effect of improving the glass sealing performance is also reduced. On the other hand, if it exceeds 25% by weight, the amount of the grain boundary phase generated at the grain boundary increases, which causes the thermal conductivity to decrease. In particular, when a large amount of the element (3) is added, the wettability of the grain boundary phase to the AlN grains is improved, and the AlN grains are separated from each other, and as a result, heat transfer is unfavorably inhibited. A more preferred addition amount is in the range of 7 to 20% by weight.

The AlN sintered body to which the compound of each of the above-mentioned elements (1), (2) and (3) is added can be densified even by low-temperature sintering at 1973K or lower, and high thermal conductivity can be obtained. At the same time, the average particle size of the AlN particles can be reduced to 2 μm or less. In other words, it is possible to suppress the coarsening of AlN grains, and it is possible to obtain higher strength than the conventional AlN sintered body due to the average grain size being 2 μm or less. AlN after sintering
If the average grain size of the crystal grains exceeds 2 μm, the mechanical strength deteriorates. Further, by adding the compound of the element (3), it is possible to improve the adhesion between the conductor layer and the AlN insulating layer and to improve the glass sealing property.

[0022]

Embodiments of the present invention will be described below.

First, a manufacturing method for realizing the AlN sintered body of the present invention will be described. The AlN sintered body of the present invention is preferably manufactured by applying the following manufacturing method.

The AlN powder used for producing the AlN sintered body of the present invention has an average primary particle size of 0.03 to 1.4 μm in consideration of the particle size after sintering among substantially available powders. Preferably, the amount of impurity oxygen is in the range of 0.2 to 3.5% by weight.

If the average primary particle diameter of the AlN powder is less than 0.03 μm, it may be difficult to handle the powder and to form the powder. On the other hand, when the average primary particle size of the AlN powder exceeds 1.4 μm,
Low-temperature sintering at 3K or less may be difficult, and the average particle size of AlN particles after sintering may exceed 2 μm, and mechanical strength may be degraded. The more preferred average primary particle size of the AlN powder is in the range of 0.05 to 1.2 μm.

The amount of impurity oxygen in the AlN powder means the amount of oxygen effectively involved in sintering immediately before sintering. If the amount of impurity oxygen is less than 0.2% by weight, 1
There is a risk that low-temperature sintering at 973K or less, especially 1873K or less will be difficult, and that the AlN material will deteriorate during the mixing and molding handling steps before sintering. -, The amount of impurity oxygen is 3.5% by weight
If it exceeds 3, there is a possibility that an AlN sintered body having high thermal conductivity cannot be obtained. A more preferable impurity oxygen amount is
It is in the range of 0.5 to 2.0% by weight.

Next, each compound containing the above-mentioned elements (1), (2) and (3) is added to the AlN powder as described above as a sintering aid. After sintering, the sintering aid present as a compound of the rare earth element (1) or a compound of the alkaline earth metal element (2) inside the AlN sintered body is added as a powder or a liquid to the AlN powder. Specifically, a solution in which an oxide, a carbonate, an oxalate, a nitrate, an alkoxide, a halide, or the like is further dissolved, and a nitrate is dissolved in an alcohol, or a combination thereof is used. Further, as the compound containing the element (3) to be added as a sintering aid, an oxide or a compound which becomes an oxide during firing is preferable, for example, carbonate, nitrate, oxalate, alkoxide, or an aqueous solution thereof. , Alcohol solutions and the like. (1),
The amount and reason for adding each compound containing the elements (2) and (3) are as described above.

In the raw material powder composed of the AlN powder and the sintering aid, if necessary, Ti,
0.05 to 1 weight of oxides, carbides, fluorides, carbonates, oxalates, nitrates, etc. of transition metals such as W, Mo, Ta, Nb, Mn
You may mix | blend in the range of%. Further, aluminum compounds such as alumina (Al ₂ O ₃ ) effective for lowering the sintering temperature, phosphorus compounds, boron compounds, and silicon oxide (SiO ₂ ), silicon nitride (Si ₃ N ₄₎
1% by weight of raw material powder
% It may be added in the following range.

It is desirable that the above mixed raw material powder comprising the AlN powder and the sintering aid is kneaded with a binder, kneaded and granulated, and then molded. As a molding method used at this time, for example, a sheet molding method such as a die press, an isostatic press, a doctor blade, or the like, or a combination thereof can be used. As a binder,
For example, acrylic, methacrylic, PVB and the like are used. As a solvent in which these binders are dispersed, for example, alcohols such as n-butanol, methyl isobutyl, toluene, xylene and the like are used. The amount of the binder varies depending on the particle size of the AlN powder used, but is preferably in the range of 2 to 12 parts by weight, more preferably 3 to 10 parts by weight, per 100 parts by weight of the mixed raw material powder. .

Next, the compact is heated to a maximum temperature of 1273K or less in a non-oxidizing atmosphere such as a nitrogen gas stream to remove vanida, and then heated in a non-oxidizing atmosphere at a temperature of 1973K or less, more preferably 1673K or less. Sinter at a temperature in the range of ~ 1973K. In the step of removing the binder, an atmosphere containing oxygen such as air or an atmosphere containing water vapor can be used by appropriately selecting a maximum temperature for heating while paying attention to oxidation of AlN and the like.

When sintering at a temperature higher than 1973 K in the sintering process described above, the compound containing the element (3) evaporates intensely, and AlN grains grow, so that the average grain size can be reduced to 2 μm or less. Difficult, resulting AlN
A problem that the strength of the sintered body is reduced occurs. Also, 167
If the temperature is less than 3K, the firing time required for complete densification becomes longer, which is not preferable. The sintering process is preferably performed at an atmospheric pressure of 0.9 atm or more. If the pressure is less than 0.9 atm, the volatilization of the compound containing the element (3) in particular becomes severe, and the effect of accelerating the sintering is reduced, and the adhesion to the conductor and the glass sealing property may not be sufficiently improved. is there.

As the non-oxidizing atmosphere during sintering, nitrogen,
A single gas or a mixed gas of argon, or a mixed gas in which a part thereof is hydrogen, CO _2, or the like can be used. In addition, it is desirable to perform sintering in a sintering furnace equipped with carbon, tungsten, molybdenum, etc. as a heater in a sintering vessel selected from AlN, BN, carbon and the like. By applying the manufacturing method as described above, the average particle size 2μ
m or less as the main component, (1) at least one selected from rare earth elements is 1 to 8% by weight in terms of oxide, (2)
0.3 to 7% by weight of at least one selected from alkaline earth metal elements in terms of oxide, and (3) Bi, Pb, Sb, In
And an AlN sintered body of the present invention containing 5 to 25% by weight of at least one element selected from Sn and Sn in terms of oxide can be obtained with good reproducibility.

The AlN sintered body of the present invention can be used as a high-temperature high-strength material, a heat sink, or the like. However, it is possible to form a conductor circuit by performing metallization or to provide a conductor layer on a molded body. It is suitably used as various circuit boards, package bases, and the like by co-firing to form conductor circuits. By using the AlN sintered body of the present invention as an insulating part, it is possible to produce circuit boards and package bases with excellent heat dissipation, mechanical strength, and good circuit characteristics without defects such as separation from the conductor layer. can do. Furthermore, when performing glass sealing by mounting a semiconductor element,
It is possible to manufacture a package with good glass sealing properties.

[0034]

Embodiments of the present invention will be described below.

Example 1 The average primary particle size was 0.6 μm and the amount of impurity oxygen was 0.9% by weight.
In the AlN powder, the average particle diameter of 0.1 [mu] m, 99.9% pure Y ² O
₃ 3.0% by weight powder, 0.2μm average particle size, 9 purity
9.9% of CaCo ₃ was added at 1.0% by weight in terms of CaO, and Bi ² O ₃ having an average particle size of 0.5 μm and a purity of 99.9% was added at 8.0% by weight.
When, 0 average particle size 0.3 [mu] m, a purity of 99.9% WO ₃ in W terms.
3% by weight, n-butanol was added thereto, and the mixture was pulverized and mixed by a wet ball mill, and then n-butanol was removed to obtain a raw material powder.

Subsequently, 5 parts by weight of an acrylic binder was added together with an organic solvent to 100 parts by weight of the raw material powder, and the mixture was granulated, and then uniaxially pressed at a pressure of 50 MPa to produce a molded body. The compact was set in a container made of an AlN sintered body, and fired at 1873 K for 6 hours in a graphite heater furnace under a 2 atm nitrogen gas atmosphere to obtain an AlN sintered body. When the density of the obtained AlN sintered body was measured by the Archimedes method, it was sufficiently dense to 3.31 g / cm ³ . Also,
When the microstructure was confirmed by observing the fractured surface of the AlN sintered body by SEM, the pores were almost completely eliminated, and from this result, it was confirmed that the AlN sintered body was completely densified. .

Further, on the surface of the AlN sintered body, color unevenness and unevenness due to the exudation of the grain boundary phase were not observed. The fractured surface of the AlN sintered body was observed by SEM, and the average particle size of the AlN particles was found to be 1.8 μm by the intercept method. Furthermore, a diameter of 10 mm and a thickness of 3 mm were obtained from the obtained AlN sintered body.
mm disk was cut out and the thermal conductivity was measured at room temperature by the laser flash method according to JIS-R1611. 142 W / m
K. When the four-point bending strength was measured according to JIS-R1601, the strength was 320 MPa, which was high despite the low sintering temperature.

On the other hand, 97% by weight of tungsten having an average particle diameter of 1.1 μm and 3% by weight of an AlN mixed powder (raw material powder) to which the above-mentioned additive was added as a filler were added to the surface of the compact produced by the above-mentioned method. A paste prepared by mixing with an organic solvent was applied by a screen printing method, and sintering was performed under the same conditions as described above. Next, after performing Ni plating on the conductor part of 2 mm square size on the obtained AlN sintered body surface,
Solder the wire and conduct tensile strength test.
The adhesion strength between the sintered body and the conductor layer was measured. As a result, the tensile strength showed a high value of 7.4 kgf / 2 mm square.

Further, two concave AlN sintered bodies were manufactured according to the method described above. After stacking the obtained two concave AlN sintered bodies so that their opening faces each other,
Glass sealing was performed using a glass having a composition shown in Table 1 below in a nitrogen atmosphere.

[0040]

[Table 1] After leaving the sealed AlN sintered body in a chamber filled with helium gas at 5 atm for 40 minutes, the inside of the chamber was
A vacuum was drawn on the order and air was introduced again to 1 atm. After performing this helium washing step three times, the sample was taken out of the chamber and left in the air for 30 minutes. After the treatment, the helium leak test (fine leak detection) was performed, and the amount of leak was detected by a mass spectrometer. As a result, the leak amount showed a good value of 1.0 × 10 ⁻¹⁰ atm · cc · sec ⁻¹ or less.

Example 2 The average primary particle size was 0.8 μm and the amount of impurity oxygen was 0.7% by weight.
Dy ₂ O with an average particle size of 0.1 μm and a purity of 99.9%
₃ Powder 5% by weight, average particle size 0.2μm, purity 99.9
1% by weight of BaCO ₃ in terms of BaO, 10% by weight of Sb ₂ O ₃ having an average particle size of 0.5 μm and a purity of 99.9%, and 0.3% by weight of TiO ₂ having a purity of 99.9% in terms of Ti Then, n-butanol was added thereto, and the mixture was pulverized and mixed by a wet ball mill, and then n-butanol was removed to obtain a raw material powder.

Subsequently, 5 parts by weight of an acrylic binder was added to 100 parts by weight of the raw material powder together with an organic solvent to granulate, and then uniaxially pressed at a pressure of 70 MPa to produce a molded body. The formed body was set in a container made of an AlN sintered body, and fired in a heater furnace made of Graphite at 1923 K for 4 hours under a nitrogen gas atmosphere of 1 atm to obtain a target AlN sintered body.

The density, thermal conductivity, and
Point bending strength, adhesion to conductors and glass sealing
When measured under the same conditions and method as in Example 1, 3.33 g / cm ³ , 153 W / m K, 311 MPa, 6.9 kgf / 2 mm square,
1.0 × 10 ⁻¹⁰ atm · cc · sec ⁻¹ or less showed good values.

Comparative Example 1 Bi ₂ O ₃ as an additive was added to the same AlN powder as in Example 1.
Was added at the same ratio as in Example 1 except that
Forming, degreasing, and sintering were performed in the same manner as in Example 1. The density of the obtained AlN sintered body was 3.28 g / cm ³ , and the average particle size was 1.4 μm. Although the thermal conductivity was 135 W / m K and the four-point bending strength was 325 MPa, observation of the microstructure of the fractured surface of the AlN sintered body by SEM showed that a small number of small pores were found somewhere inside the sintered body. And it was not a completely dense AlN sintered body.

When the adhesion to the conductor was evaluated in the same manner as in Example 1, a value as low as 3.5 kgf / 2 mm square was obtained. Further, when the glass sealing property was evaluated by the helium leak characteristic in the same manner as in Example 1, it was found that 5.0 × 10 5
^The value was as large as ^-7 atm · cc · sec ⁻¹ , confirming that the glass sealing property was low.

Comparative Example 2 An AlN raw material powder having the same sintering aid and additives as in Example 1 was prepared, molded and degreased, and then subjected to 2073K × 2 hours in a carbon furnace. Sintered. The resulting density of the AlN sintered body is densified and 3.30 g / cm ^3, thermal conductivity 178W / m
Although it was as high as K, the average grain size of the AlN grains was 8.7 μm and the grains grew, and the four-point bending strength was as low as 190 MPa as compared with Example 1. Furthermore, when the adhesion to the conductor and the glass sealing property were evaluated in the same manner as in Example 1, 2.7 kgf / 2 mm square,
The value was 6.8 × 10 ⁻⁷ atm · cc · sec ⁻¹ which was an insufficient value.

Examples 3 to 12 The same procedures as in Example 1 were carried out except that the AlN powder, sintering aid and additives shown in Table 2 below were used, and the sintering conditions were the pressure, temperature and time shown in Table 2. In the same manner, ten types of AlN sintered bodies were produced. In Example 6, Y ₂ O ₃
Was added by dissolving Y (NO ₃ ) ₃ .6H ₂ O in n-butanol.

With respect to the obtained AlN sintered bodies of Examples 3 to 12, the density, thermal conductivity, average particle size, four-point bending strength, adhesion to a conductor, and glass sealing property were determined as in Example 1. Evaluation was performed in the same manner. The results are shown in Table 3 below.

[0049]

[Table 2]

[Table 3]

[0050]

As described above, the AlN sintered body of the present invention has fine AlN crystal grains and is sufficiently dense despite being sintered at a low sintering temperature of 1973K or less. Has high thermal conductivity. In addition, AlN has high mechanical strength due to small particle size, strong adhesion with conductors based on the type of sintering aid, and good sealing performance when glass sealing is performed. A sintered body can be provided. Therefore, the AlN sintered body of the present invention can be effectively used not only as a structural material based on high strength and high thermal conductivity, but also as a constituent material for metallized substrates, multilayer co-fired circuit boards, and package bases. Can be applied.

[0051]

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Fumio Ueno 1-Toshiba-cho, Komukai, Koyuki-ku, Kawasaki-shi, Kanagawa Prefecture Toshiba R & D Center (56) References JP-A-4-130064 (JP, A) ( 58) Fields surveyed (Int. Cl. ⁶ , DB name) C04B 35/581 H05K 1/00

Claims (1)

(57) [Claims] An aluminum nitride particle having an average particle size of 2 μm or less as a main component, and at least one selected from rare earth elements.
One type is 1 to 8% by weight in terms of oxides, and at least one type selected from alkaline earth metal elements is 0.3 to 7 in terms of oxides.
An aluminum nitride sintered body characterized in that it contains, by weight, at least one element selected from the group consisting of Bi, Pb, Sb, In and Sn in an amount of 5 to 25% by weight in terms of oxide.