JP2001322874A - Aluminum nitride sintered body and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aluminum nitride sintered body and a method for manufacturing the body which makes low temperature sintering possible and which is excellent in strength or the like compared to conventional aluminum nitride and to provide an aluminum nitride sintered body and a method for manufacturing the body which can be sintered at low temperature and which is excellent in both of strength and thermal conductivity. SOLUTION: The sintered body contains 2 to 10 wt.% doxide of at least one kind of element selected from Sm and Nd, 0.15 to 1.5 wt.% elf boron compound calculated as the B component, and 0.01 to 0.2 wt.% silicon compound expressed in terms of the silicon component, and the balance of aluminum nitride.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum nitride sintered body used for a semiconductor substrate and the like, and more particularly to an aluminum nitride sintered body excellent in strength and toughness, and a method for producing the same. .

[0002]

2. Description of the Related Art Sintered ceramics having superior properties such as strength, heat resistance, corrosion resistance, abrasion resistance and light weight as compared with conventional metal materials are used for semiconductor substrates, electronic equipment materials,
It is used for machine parts used in harsh environments that cannot be handled by conventional metal materials, such as materials for engines and materials for high-speed cutting tools.

[0003] In particular, an aluminum nitride sintered body is an insulator having a high thermal conductivity, and has a thermal expansion coefficient close to that of silicon (Si), so that it is used as a heat sink or a substrate for a highly integrated semiconductor device. Is expanding.

[0004] The aluminum nitride sintered body is generally mass-produced by the following manufacturing method. That is, a sintering aid, an organic binder,
A raw material mixture is prepared by adding various additives, solvents, and dispersants as necessary, and the obtained raw material mixture is formed by a doctor blade method or a slurry casting method (slip casting method) to obtain a thin plate or A sheet-shaped molded product or a raw material mixture is press-formed to form a thick or large molded product. Next, the obtained molded body is heated and degreased in an air or nitrogen gas atmosphere, and the hydrocarbon component and the like used as the organic binder are removed and degreased from the molded body. Then, the degreased molded body is heated to a high temperature in a nitrogen gas atmosphere or the like and densified and sintered to form an aluminum nitride sintered body.

In the above-mentioned production method, when an ultrafine raw material powder having an average particle size of about 0.5 μm or less is used as the raw aluminum nitride powder, a fairly dense sintered body can be obtained by using the aluminum nitride powder alone.

On the other hand, when an aluminum nitride powder having an average particle size of 1 μm or more is used as a raw material powder, the sinterability is not good when the raw material powder alone is used. It was difficult to obtain a sintered body, and there was a drawback that mass productivity was low. Therefore, when trying to produce a sintered body efficiently by the normal pressure sintering method,
In order to densify the sintered body and to prevent impurity oxygen in the aluminum nitride raw material powder from forming a solid solution in the aluminum nitride crystal particles, yttrium oxide (Y ₂
It is common practice to add rare earth oxides such as O ₃ ) or alkaline earth metal oxides such as calcium oxide.

[0007] These sintering aids react with impurity oxygen or Al ₂ O ₃ contained in aluminum nitride to form a liquid phase, thereby achieving densification of the sintered body and at the same time reduce the impurity oxygen to the grain boundaries. It is considered that they are fixed as phases to achieve high thermal conductivity.

[0008]

However, in the above-mentioned conventional production method, the wettability between aluminum nitride and the liquid phase compound is originally low, and the liquid phase itself tends to segregate. When the liquid phase solidifies,
The liquid phase remains unevenly distributed in the gaps between the aluminum nitride particles and tends to solidify to form a coarse and brittle grain boundary phase.

In order to solve the above problems, an aluminum nitride sintered body having a crystal structure as fine as possible is formed by using a fine aluminum nitride raw material powder having a uniform particle size, and various additives are used. Attempts have been made to increase the sinterability by adding sintering. For example, a method of obtaining a high-strength aluminum nitride sintered body by improving the sinterability by incorporating a W component or the like has been devised. However, it has been found that the inclusion of the W component makes the crystal structure fine and uniform, so that the strength of the sintered body is improved, but the fracture toughness value is conversely reduced.

When a sintering aid such as Y ₂ O ₃ is used, a sintering temperature of about 1700 ° C. to 1800 ° C. is required, and a reduction in the sintering temperature has been required. Furthermore, Y ₂
When a sintering aid such as O ₃ is used, the strength of the obtained sintered body is usually about 400 MPa, and when used together with other sintering aids, only a maximum of about 500 MPa can be obtained. Therefore, improvement in strength is required.

In recent years, aluminum nitride materials having high thermal conductivity (high heat dissipation) have become widespread in order to cope with an increase in the amount of heat generated with higher integration and higher output of semiconductor elements. However, since the strength and toughness of the structural member are insufficient as described above, for example, a slight bending stress acting when mounting a semiconductor substrate formed of an aluminum nitride sintered body on a mounting board or an impact force acting during handling As a result, there is a problem that the semiconductor substrate is easily damaged and the production yield of the semiconductor circuit substrate is significantly reduced. In addition, it is necessary to fire the aluminum nitride sintered body at a high temperature, and a reduction in the firing temperature is required from the viewpoint of cost and time.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has a lower firing temperature and improved strength as compared with a conventional aluminum nitride sintered body, and an aluminum nitride sintered body having the same. It is intended to provide a manufacturing method.

[0013]

The aluminum nitride sintered body of the present invention contains 2 to 10% by weight of an oxide of at least one element selected from Sm and Nd, and contains a boron compound in an amount of 0.1 to 10 wt. It is characterized by containing 15 to 1.5% by weight and 0.01 to 0.2% by weight of a silicon compound in terms of a Si component, with the balance being aluminum nitride.

As the silicon compound, SiO ₂ , S
i ₃ N ₄ , Si ₂ N ₂ O, SiC, β-sialon, α
- sialon, preferably made of at least one selected from mullite and polytypes of aluminum nitride (Al-Si-O-N ), examples of the boron _{compound, B 4 C, B 2 O} 3, AlB 2 and It is preferable to use at least one selected from TiB ₂ .

The sintered aluminum nitride of the present invention is
f, Zr, Ti, W, Mo, Ta, Fe, Ni, Cr,
It is preferable that at least one metal element selected from Co, Li, and Mg is contained in an amount of 2% by weight or less in terms of oxide.

Further, the aluminum nitride sintered body of the present invention preferably contains 0.1 to 1% by weight of Ca element in terms of oxide.

Further, the aluminum nitride sintered body of the present invention preferably contains 1 to 4% by weight of a Y oxide. The content of the Y oxide is preferably such that the ratio obtained by dividing the total weight of the Sm oxide and the Nd oxide by the weight of the Y oxide is in the range of 1.5 to 7.5. .

The aluminum nitride sintered body of the present invention has a three-point bending strength of 500 MPa or more and a fracture toughness of 3
It is preferably at least MPa · m ^1/2 .

Further, the aluminum nitride sintered body of the present invention preferably has a thermal conductivity of 130 W / m · K or more.

The method for producing aluminum nitride according to the present invention comprises:
An aluminum nitride raw material powder contains 2 to 10% by weight of an oxide of at least one element selected from Sm and Nd, a boron compound of 0.15 to 1.5% by weight in terms of a B component, and a silicon compound. Forming a mixed powder containing 0.01 to 0.2% by weight in terms of Si component; and sintering the formed body at 1700 ° C. or lower in a non-oxidizing atmosphere. Is what you do.

The silicon compound includes SiO ₂ , S
i ₃ N ₄ , Si ₂ N ₂ O, SiC, β-sialon, α
- sialon, preferably made of at least one selected from mullite and polytypes of aluminum nitride (Al-Si-O-N ), also the boron compound is _{B 4 C, B 2 O 3} , AlB 2 and TiB Those composed of at least one selected from ₂ are preferred.

The aluminum nitride raw material powder 2
% By weight of Hf, Zr, Ti, W, Mo, Ta, F
It is preferable to replace with an oxide of at least one metal element selected from e, Ni, Cr, Co, Li, and Mg.

Further, it is more preferable to substitute 0.1 to 1% by weight of the aluminum nitride raw material powder with Ca oxide.

Further, in the method for producing an aluminum nitride sintered body according to the present invention, the aluminum nitride raw material powder may be prepared by mixing
It is preferred that the weight% is replaced by Y oxide. As a substitution amount of the Y oxide, a ratio obtained by dividing the total weight of the Sm oxide and the Nd oxide by the weight of the Y oxide is 1.5.
Those which fall within the range of -7.5 are preferred.

In the method for producing aluminum nitride according to the present invention, it is more preferable that the aluminum content of the aluminum nitride raw material powder is 1.5% by weight or less.

The aluminum nitride sintered body of the present invention has
2 to 10% by weight of an oxide of at least one element selected from m and Nd;
Compared with conventional aluminum nitride sintered bodies by containing 5 to 1.5% by weight and 0.01 to 0.2% by weight of silicon compound in terms of Si component, with the balance being aluminum nitride Thus, sintering at a low temperature becomes possible, and the strength can be greatly improved.

As the silicon compound, SiO ₂ , Si
₃ N ₄ , Si ₂ N ₂ O, SiC, β-sialon, α-
Sialon, at least one selected from mullite and polytypes of aluminum nitride (Al-Si-O-N ), as the boron _{compound, B 4 C, B 2 O} 3,
By using at least one selected from AlB ₂ and TiB ₂ , sinterability and fracture toughness can be improved.

Further, Hf, Zr, Ti, Nb, W, M
By containing at least one metal element selected from the group consisting of o, Ta, Fe, Ni, Cr, Co, Li, and Mg in an amount of 2% by weight or less in terms of oxide, generation of a surface liquid phase of the sintered body is suppressed. It is possible to improve surface smoothing and the like.

Further, the content of Ca element is 0.1 to
By containing 1% by weight, sinterability can be further improved, and strength and the like can be improved.

Further, in the aluminum nitride sintered body of the present invention, the thermal conductivity can be controlled by containing 1 to 4% by weight of the Y oxide. The content of the Y oxide is such that the ratio of the total weight of the Sm oxide and the Nd oxide divided by the weight of the Y oxide is in the range of 1.5 to 7.5. An aluminum nitride sintered body having excellent properties of strength and thermal conductivity can be obtained.

The aluminum nitride sintered body of the present invention has a three-point bending strength of 500
MPa or more, and the fracture toughness value can be 3 MPa · m ^1/2 or more.

Further, the aluminum nitride sintered body of the present invention can have a thermal conductivity of 130 W / m · K or more while ensuring strength by using the above composition.

The method for producing aluminum nitride of the present invention comprises:
An aluminum nitride raw material powder contains 2 to 10% by weight of an oxide of at least one element selected from Sm and Nd, a boron compound of 0.15 to 1.5% by weight in terms of a B component, and a silicon compound. By using a mixed powder added in an amount of 0.01 to 0.2% by weight in terms of Si component, sintering at 1700 ° C. or less is possible and a sintered body excellent in strength can be produced.

As the silicon compound, SiO ₂ , S
i ₃ N ₄ , Si ₂ N ₂ O, SiC, β-sialon, α
- sialon, mullite and at least one member selected from the polytypes of aluminum nitride (Al-Si-O-N ), also B ₄ C as the boron compound, B ₂
By using at least one selected from O ₃ , AlB ₂ and TiB _2, the introduction of the Si component and the B component into the sintered body is facilitated, and the sinterability is easily improved. Becomes possible.

The aluminum nitride raw material powder 2
% By weight of Hf, Zr, Ti, Nb, W, Mo, T
a, by replacing with an oxide of at least one metal element selected from Fe, Ni, Cr, Co, Li, and Mg, the sinterability is improved and the liquid phase generated on the surface of the sintered body is improved. Aggregation and segregation can be suppressed.

Further, by replacing 0.1 to 1% by weight of the aluminum nitride raw material powder with Ca oxide, an aluminum nitride sintered body having further improved sinterability and excellent strength, toughness and the like. Can be manufactured.

Further, in the method for producing an aluminum nitride sintered body according to the present invention, the aluminum nitride raw material powder may be 1 to 4
By substituting the weight% with the Y oxide, it is possible to improve the thermal conductivity while securing the strength. This Y
As a substitution amount of the oxide, a ratio obtained by dividing the total weight of the Sm oxide and the Nd oxide by the weight of the Y oxide is 1.
By setting the content in the range of 5 to 7.5, it is possible to produce an aluminum nitride sintered body excellent in both strength and thermal conductivity.

In the method for producing aluminum nitride of the present invention, the sinterability can be further improved by setting the oxygen content of the aluminum nitride raw material powder to 1.5% by weight or less.

[0039]

BEST MODE FOR CARRYING OUT THE INVENTION The aluminum nitride sintered body of the present invention contains 2 to 10% by weight of an oxide of at least one element selected from Sm and Nd, and contains 0.15 to 5% by weight of a boron compound in terms of a B component. It contains 1.5% by weight and a silicon compound in an amount of 0.01 to 0.2% by weight in terms of a Si component, with the balance being aluminum nitride.

The aluminum nitride sintered body of the present invention has a three-point bending strength of 500MP
a, a fracture toughness value of 3 MPa · m ^1/2 or more, and a thermal conductivity of 130 W / m · K or more.

In the above structure, the oxide of Sm or Nd acts as a sintering aid and is added to densify the aluminum nitride sintered body. Sm or Nd
By using the oxide of the present invention, the strength is 100 to 2 times as compared with the conventional one using a sintering agent mainly containing Y ₂ O _3.
It is possible to increase the pressure by about 00 MPa. Further, the firing temperature can be significantly reduced.
The content of the oxide of Sm or Nd is preferably 2 to 10% by weight in order to improve strength and toughness. When the content is less than 2% by weight, the thermal conductivity is low, the effect of improving strength and toughness is small, and the content is 1%.
If the content exceeds 0% by weight, the effect as a sintering aid reaches a saturated state and becomes meaningless, and rather, the thermal conductivity of the aluminum nitride sintered body obtained by sintering decreases. Since a large amount of the grain boundary phase remains in the sintered body and the volume of the grain boundary phase removed by the heat treatment increases, pores may be generated in the sintered body or the shrinkage may increase. There is.

The silicon compound has the effect of improving the sinterability and lowering the sintering temperature. In particular, by adding the compound together with the sintering aid, the grain growth of the sintered body is suppressed and the fineness is reduced. An aluminum nitride crystal structure can be formed, and the structural strength of the sintered body can be increased. Examples of the silicon compound include SiO ₂ , Si ₃ N ₄ , Si ₂ N ₂ O, and Si.
It is desirable to use silicon compounds such as C, β-sialon, α-sialon, mullite and polytype aluminum nitride (Al-Si-ON). The content of the silicon compound is preferably adjusted to a range of 0.01 to 0.2% by weight or less in terms of Si component. When the content of the Si component is less than 0.01% by weight, the effect of suppressing grain growth is insufficient, so that a coarse crystal structure is formed and a high-strength aluminum nitride sintered body may not be obtained.
On the other hand, when the content exceeds 0.2% by weight, the thermal conductivity of the sintered body decreases, and the bending strength may decrease.

The boron compound enhances the degree of bonding between the grain boundary phase and the crystal grains of the aluminum nitride sintered body, and exhibits a function of uniformly dispersing in the structure of the sintered body to prevent the propagation of cracks. This has the effect of further improving the fracture toughness value of the aluminum sintered body. The content of the boron compound is preferably adjusted in the range of 0.15 to 1.5% by weight in terms of the B component. When the content of the component B is less than 0.15% by weight, the effect of improving the toughness becomes insufficient, and when the content exceeds 1.5% by weight, the thermal conductivity of the sintered body decreases. There is a risk that it will. Such boron compounds include B ₄ C, B ₂ O ₃ , AlB ₂
It is preferable to use at least one selected from TiB ₂ and TiB ₂ .

In the present invention, strength and toughness can be further improved by adding other components in addition to the sintering aid and the like. Hereinafter, the types and effects of those found useful in the present invention will be described.

The Hf component and the Zr component have the effects of further improving the sinterability, suppressing the aggregation and segregation of the liquid phase which is likely to be generated on the surface of the sintered body, and expanding the temperature range in which the sintering can be performed appropriately. As the source of the above components, compounds such as oxides, carbides, nitrides, silicides, borides, etc. of the respective components can be used. The Hf compound and the Zr compound are preferably added in a range of 2% by weight or less in terms of oxide. If the amount of addition exceeds 2% by weight, the thermal conductivity of the aluminum nitride sintered body is reduced as in the case of other impurities.

Ti, W, Mo, Ta, Fe, Ni, C
The oxides of r, Co, Li and Mg improve the sinterability by lowering the sintering temperature, while coloring the sintered body to form an opaque sintered body. It is effective to improve the content, and it is preferable to contain 2% by weight or less in terms of oxide. If the content exceeds 2% by weight, the thermal conductivity of the aluminum nitride sintered body may be reduced as in the case of other impurities.

Further, impurity cations other than the above-mentioned various additives are liable to form a compound that inhibits the heat conduction of the aluminum nitride sintered body, so that the content in the aluminum nitride sintered body is 0.2% by weight or less. Is preferred.

In the present invention, Y oxide may be contained in an amount of 1 to 4% by weight in order to improve the thermal conductivity and the like. By adding the Y oxide, it is possible to improve the thermal conductivity while maintaining the strength of the aluminum nitride sintered body. However, since the content of a large amount of Y oxide lowers the strength, the content is preferably about 1 to 4% by weight as described above. Further, the Y oxide preferably has a ratio of the total weight of the Sm oxide and the Nd oxide divided by the weight of the Y oxide as 1.5 as shown in the following equation.
It is preferable that the content be contained in the range of 7.5 to 7.5.

1.5 ≦ (Sm oxide + Nd oxide) /
Y oxide ≦ 7.5 By setting the content in such a range, it is possible to obtain an aluminum nitride sintered body excellent in both strength and thermal conductivity.

The aluminum nitride sintered body of the present invention is produced, for example, as follows.

Sm, Nd was added to the aluminum nitride raw material powder.
Oxides of at least one element selected from
0% by weight, the boron compound is 0.15 to 1.
5% by weight and a silicon compound in an amount of 0.0
The mixed powder added in an amount of 1 to 0.2% by weight is put into a pulverizer / mixer such as a ball mill and mixed for a predetermined time to prepare a raw material mixture. Next, the obtained raw material mixture is filled in a mold having a predetermined shape, and is subjected to pressure molding to form a molded body. At this time, by adding 5 to 10% by weight of an organic binder such as paraffin or stearic acid to the raw material mixture in advance, the molding operation can be performed smoothly. As the molding method,
General-purpose mold pressing, slurry casting, isostatic pressing,
An extrusion molding method or a sheet molding method such as a doctor blade method can be applied.

Following the above molding operation, the molded body is heated to a temperature of 400 to 550 ° C. in the air, or is heated to a temperature of 400 to 8 in a non-oxidizing atmosphere, for example, a nitrogen gas atmosphere.
By heating to 00 ° C., the organic binder added in advance is sufficiently degreased and removed.

Next, the plurality of sheet-shaped compacts subjected to the degreasing treatment are laminated in a multi-stage manner in a firing furnace via, for example, a sintering powder made of ceramic sintered powder. At a predetermined temperature. In the sintering operation, the compact is heated at a temperature of 17 in a non-oxidizing atmosphere such as nitrogen gas.
Heating is performed at a temperature of not more than 00 ° C. for about 2 to 6 hours.

In the method for producing an aluminum nitride sintered body of the present invention, Sm oxide and Nd oxide are mainly used as sintering aids, and Si component and B component are added.
It is possible to set the sintering temperature significantly lower than that of the conventional one. Further, by adopting the above composition, it is possible to improve the properties such as the strength and toughness of the sintered body despite the lower sintering temperature. In particular,
In the present invention, by setting the amount of Sm oxide or the like to an optimum value,
By sintering at about 1600 ° C., it is possible to obtain an aluminum nitride sintered body having a strength of 600 MPa or more.

In the production method of the present invention, in addition to the above components,
By adding at least one of Hf and Zr, it is possible to perform sintering at a lower temperature and to suppress aggregation and segregation of a liquid phase generated on the surface of a sintered body.

Further, Ti, Nb, W, Mo, Ta, F
e, by adding oxides of Ni, Cr, Co, Li and Mg, lowering the sintering temperature to improve sinterability, coloring the sintered body to form an opaque sintered body, etc. The characteristics of the aluminum nitride sintered body can be improved. Sufficient effects can be obtained by containing these elements in an amount of 2% by weight or less in terms of oxides. Content 2% by weight
If it exceeds, the effect is the same as when 2% by weight,
On the contrary, the properties such as the thermal conductivity of the aluminum nitride sintered body may be reduced.

In the present invention, the thermal conductivity can be improved by replacing 1 to 4% by weight of the aluminum nitride raw material powder with Y oxide. This Y oxide is preferably contained so that the ratio of the total weight of the Sm oxide and the Nd oxide divided by the weight of the Y oxide is in the range of 1.5 to 7.5. . With such a range, an aluminum nitride sintered body excellent in both strength and thermal conductivity can be manufactured.

Further, in the present invention, by setting the oxygen content in the raw material aluminum nitride powder to 1.5% by weight or less, it is possible to further promote the densification and improve the strength.

[0059]

EXAMPLES Next, in order to evaluate the effect of the present invention, characteristics such as strength, toughness, and thermal conductivity were measured while changing the type and amount of the sintering aid.

Examples 1 to 18 Sm oxide was added as a sintering aid to aluminum nitride raw powder having an oxygen content of 0.8% by weight and an average particle diameter of 1 μm, which was produced by a reduction nitridation method. Used, and further, as shown in Table 1, a Si component, a B component, and other components were added within a range of the addition amount specified in the present invention, and ethyl alcohol was added thereto as a solvent.
The mixture was mixed by a ball mill for 48 hours to prepare a raw material mixture.
Next, 7.5% by weight of paraffin as an organic binder was added to this raw material mixture to prepare granulated powder.

Next, the obtained granulated powder is filled in a molding die of a press molding machine, and at a pressure of 1000 kg / cm ² ,
A large number of square plate-shaped molded bodies having a length of 50 mm, a width of 50 mm and a thickness of 5 mm were prepared by compression molding in a uniaxial direction. Subsequently, each compact was heated in air at 450 ° C. for 1 hour to perform a degreasing treatment.

Next, each of the degreased compacts is accommodated in an aluminum nitride firing container, and densified and sintered at a temperature (1700 ° C. or less) shown in Table 1 for 4 hours in a firing furnace, followed by cooling. It was cooled at a rate of 200 ° C./hr to produce an aluminum nitride sintered body.

Examples 19 and 20 Aluminum nitride sintered bodies were manufactured using Nd oxide as a sintering aid. In addition, except that Nd oxide was used,
Molding, degreasing, sintering, and the like were performed under the same conditions as in Example 1.

Examples 21 to 23 Aluminum nitride sintered bodies were manufactured using Sm oxide and Nd oxide as sintering aids. In addition, molding, degreasing, sintering, etc. were performed under the same conditions as in Example 1 except that both the Sm oxide and the Nd oxide were used as the sintering aid.

Examples 24 to 26 Aluminum nitride sintered bodies were manufactured using Sm oxide and Y ₂ O ₃ as sintering aids. Molding, degreasing, sintering, etc. were performed under the same conditions as in Example 1 except that both Sm oxide and Y ₂ O ₃ were used as sintering aids.

Example 27 An aluminum nitride sintered body was manufactured using Nd oxide and Y ₂ O ₃ as a sintering aid. Molding, degreasing, sintering, etc. were performed under the same conditions as in Example 1 except that both Nd oxide and Y ₂ O ₃ were used as sintering aids.

Example 28 As sintering aids, Sm oxide, Nd oxide and Y ₂ O
₃ was used to produce an aluminum nitride sintered body. In addition,
Sm oxide, Nd oxide and Y ₂ O ₃ as sintering aids
Molding, degreasing, under the same conditions as in Example 1 except that
Sintering and the like were performed.

Examples 29 to 36 Using Sm oxide or Ca oxide as necessary as a sintering aid, a predetermined B component and Si component, and further, Hf,
Aluminum nitride sintered bodies to which oxides of Zr and Ti were added at the ratios shown in Table 2 were produced. In addition, molding, degreasing, sintering, and the like were performed under the same conditions as in Example 1 except that the ratio of each component was different.

Table 1 shows the ratio of the raw material mixture of Examples 1 to 20, and Table 2 shows the ratio of the raw material mixture of Examples 21 to 36.

[0070]

[Table 1]

[Table 2] Comparative Example 1 On the other hand, as shown in Table 1, an aluminum nitride sintered body was produced by adding only Y ₂ O ₃ as a sintering aid and without adding any other additives. In addition, sintering was performed at 1780 ° C., and degreasing and molding were performed in the same manner as in Example 1.

Comparative Example 2 An aluminum nitride sintered body was prepared in the same manner as in Example 1 except that Y ₂ O ₃ was added as a sintering aid, and a Si component, a B component and other components were added. The sintering was 1750
C., and degreasing, molding, etc. were performed in the same manner as in Example 1.

Comparative Examples 3 to 15 Although the same components as those used in the present invention were used,
An aluminum nitride sintered body was prepared in which the amount of components was outside the preferred range of the present invention. The conditions were the same as in Example 1 except that the sintering temperature was as shown in Table 3.

Table 3 shows the proportions of the raw material mixtures of Comparative Examples 1 to 15.

[0074]

[Table 3] Examples 1 to 36 and Comparative Example 1 thus obtained
In order to evaluate the characteristics of each of the aluminum nitride sintered bodies according to Nos. To 15, the three-point bending strength, fracture toughness, thermal conductivity, and average crystal grain size (D50) of each sample were observed. Example 1
The results of 20, 20, 36 and Comparative Examples 1 to 15 are shown in Tables 4, 5, and 6, respectively.

The fracture toughness value was measured by the Niihara method in the microindentation method.

[0076]

[Table 4]

[Table 5]

[Table 6] As is clear from the results shown in Tables 4 to 6, in the aluminum nitride sintered body of the present invention to which an appropriate amount of Sm oxide and / or Nd oxide was added as a sintering aid, despite the low firing temperature, It was found that very high strength and toughness were obtained. It was also found that the aluminum nitride sintered body of the present invention to which Y ₂ O ₃ was further added was able to improve the thermal conductivity while maintaining high strength.

In particular, 1.5 ≦ (Sm oxide + Nd oxide) / Y ₂ O ₃ ≦
It was recognized that the one with 7.5 was excellent in balance between strength and thermal conductivity.

On the other hand, in the case of using only the conventionally used sintering aid, Y ₂ O ₃ , the heat conductivity is high, but the strength is low and the firing temperature must be increased. It was confirmed that it did not become. In addition, it was found that in the case where a Si component and a B component were further added in addition to Y ₂ O ₃ , although the strength was slightly improved, firing still had to be performed at a high temperature.

Further, when the Si component, the B component, etc. are added in excess of the amounts specified in the present invention, not only the strength is not improved, but also the thermal conductivity is lowered. Was found to be optimal.

[0080]

The sintered aluminum nitride of the present invention has
2 to 10% by weight of an oxide of at least one element selected from m and Nd;
5 to 1.5% by weight, and 0.01 to 0.2% by weight of a silicon compound in terms of Si component, and aluminum nitride as the balance enables sintering at a low temperature and strength. , Toughness and the like can also be improved.

Further, the aluminum nitride sintered body of the present invention can control the thermal conductivity by containing the Y oxide, and is excellent in both the strength and the thermal conductivity. can do.

In the method for producing an aluminum nitride sintered body according to the present invention, an aluminum nitride raw material powder contains 2 to 10% by weight of an oxide of at least one element selected from Sm and Nd, and a boron compound in terms of a B component. From 0.15 to 1.5% by weight, and from 0.01 to 1.5% by weight of silicon compound in terms of Si component.
By using a mixed powder added with 0.2% by weight, 17%
Sintering can be performed at a relatively low temperature of 00 ° C. or less, and a sintered body excellent in strength can be manufactured.

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Claims (16)

[Claims] At least one selected from Sm and Nd
2 to 10% by weight of the oxide of the element, and B as the boron compound
An aluminum nitride sintered body containing 0.15 to 1.5% by weight in terms of a component, and 0.01 to 0.2% by weight in terms of a Si component, and the balance being aluminum nitride. . 2. The method according to claim 1, wherein the silicon compound is SiO ₂ , Si _{3
N 4, Si 2 N 2 O} , SiC, β- sialon, alpha-sialon, at least one selected from mullite and polytypes of aluminum nitride (Al-Si-O-N )
And the boron compound is B ₄ C, B ₂ O ₃ , A
lB ₂ and TiB ₂ that consists of at least one selected from and wherein the claim 1 aluminum nitride sintered body according. 3. Hf, Zr, Ti, Nb, W, Mo, T
3. The sintered aluminum nitride according to claim 1, wherein the sintered body contains at least one metal element selected from a, Fe, Ni, Cr, Co, Li, and Mg in an amount of 2% by weight or less in terms of oxide. body. 4. The aluminum nitride sintered body according to claim 1, wherein the sintered body contains 0.1 to 1% by weight of Ca element in terms of oxide. 5. The aluminum nitride sintered body according to claim 1, comprising 1 to 4% by weight of a Y oxide. 6. A ratio of the total weight of the Sm oxide and the Nd oxide divided by the weight of the Y oxide is 1.5 to 7.5.
6. The aluminum nitride sintered body according to claim 5, wherein 7. The aluminum nitride sintered body according to claim 1, wherein the three-point bending strength is 500 MPa or more. 8. The aluminum nitride sintered body according to claim 1, wherein a fracture toughness value is 3 MPa · m ^1/2 or more. 9. The aluminum nitride sintered body according to claim 1, wherein the aluminum nitride sintered body has a thermal conductivity of 130 W / m · K or more. 10. An aluminum nitride raw material powder containing Sm,
Oxide of at least one element selected from Nd
0.1 to 10% by weight, and the boron compound is 0.15 to
Producing a compact from a mixed powder containing 1.5% by weight and a silicon compound added in an amount of 0.01 to 0.2% by weight in terms of Si component; and heating the compact at 1700 ° C. in a non-oxidizing atmosphere. A method for producing an aluminum nitride sintered body, comprising a step of sintering below. 11. The silicon compound is composed of SiO ₂ , Si
₃ N ₄ , Si ₂ N ₂ O, SiC, β-sialon, α-
Sialon, consists of at least one selected from mullite and polytypes of aluminum nitride (Al-Si-O-N ), the boron compound is _{B 4 C, B 2 O 3} ,
AlB ₂ and the manufacturing method of claim 10 aluminum nitride sintered body according to characterized in that it consists of at least one selected from TiB _2. 12. Hf, Zr, Ti, W, Mo, Ta, F
The method for producing an aluminum nitride sintered body according to claim 10 or 11, wherein the aluminum nitride sintered body is replaced with an oxide of at least one metal element selected from e, Ni, Cr, Co, Li, and Mg. 13. The method of claim 1 wherein the aluminum nitride raw material powder is used in a 0.1.
The method for producing an aluminum nitride sintered body according to any one of claims 10 to 12, wherein 1 to 1% by weight is replaced by a Ca oxide. 14. The aluminum nitride raw material powder
The method for producing an aluminum nitride sintered body according to any one of claims 10 to 13, wherein 4% by weight of Y oxide is substituted. 15. A ratio obtained by dividing the total weight of the Sm oxide and the Nd oxide by the weight of the Y oxide is 1.5 to 7.
The method for producing an aluminum nitride sintered body according to claim 14, wherein the range is within the range of 5. 16. The method for producing an aluminum nitride sintered body according to claim 10, wherein the oxygen content of the aluminum nitride raw material powder is 1.5% by weight or less.