JPH08157261A - Aluminum nitride sintered compact and its production - Google Patents

Abstract

PURPOSE: To obtain an AlN sintered compact maintaining high heat conductivity peculiar to an AlN sintered compact, having denseness comparable to or higher than that of a conventional AlN sintered compact and also having improved corrosion resistance and mechanical strength even in the case of production by sintering at a low temp. especially of <=1,650 deg.C. CONSTITUTION: This aluminum nitride sintered compact is obtd. by firing at a low temp. of <=1,650 deg.C and consists of, by weight, 0.5-7% oxide of at least one kind of group IIIa element of the Periodic Table, 0.5-3% calcium oxide, <=1.5% aluminum oxide, 0.2-1% glass frit, <=0.5% at least one selected from among manganese oxide, chromium oxide, zirconium oxide, strontium oxide and titanium oxide, <=1% (expressed in terms of oxide) tungsten and the balance 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 as an electronic component such as a semiconductor substrate or a structural component and a method for manufacturing the same, and in particular, it is formed by sintering at a low temperature of 1650 ° C. or lower. Even in such a case, an aluminum nitride sintered body having high thermal conductivity inherent to an aluminum nitride (AlN) sintered body, having a density equal to or higher than that of a conventional AlN sintered body, and further having improved corrosion resistance, It relates to a manufacturing method.

[0002]

2. Description of the Related Art Sintered ceramics, which are superior in properties such as strength, heat resistance, corrosion resistance, wear resistance, and lightness, compared with conventional metal materials, are used in semiconductor substrates, electronic equipment materials, engine members, It is widely used as materials for high speed cutting tools, nozzles, bearings, etc. as mechanical parts, functional parts, structural materials and decoration materials used under severe temperature, stress and wear conditions that conventional metal materials do not reach.

In particular, an aluminum nitride (AlN) sintered body is an insulator having a high thermal conductivity and has a coefficient of thermal expansion close to that of silicon (Si). Therefore, the aluminum nitride (AlN) sintered body is used as a heat sink or a substrate of a highly integrated semiconductor device. Expanding applications.

Conventionally, the above-mentioned aluminum nitride sintered body is generally mass-produced by the following manufacturing method. That is,
A sintering aid to the aluminum nitride raw material powder, an organic binder, and various additives and solvents as required, to prepare a raw material mixture by adding a dispersant, the resulting raw material mixture doctor blade method or A thin plate-shaped or sheet-shaped molded body is formed by the slurry casting method, or a raw material mixture is press-molded to form a thick plate-shaped or large-sized molded body. Next, the obtained molded product is heated and degreased in an atmosphere of air or nitrogen gas to remove and degrease the hydrocarbon components and the like used as the organic binder from the molded product. Then, the degreased compact is 1700 to 1700 in a non-oxidizing atmosphere such as nitrogen gas.
It is heated to a high temperature of about 1900 ° C. and densified and sintered to form an aluminum nitride sintered body.

In the above manufacturing method, when an ultrafine raw material powder having an average particle diameter of about 0.5 μm or less is used as the raw material AlN powder, a considerably dense sintered body can be obtained by using the AlN powder alone. However, a large amount of impurities such as oxygen adhering to the surface of the raw material powder and the like are solid-solved in the AlN crystal lattice at the time of sintering, or Al-O- which hinders the propagation of lattice vibration.
As a result of producing a compound oxide such as an N compound, the thermal conductivity of the AlN sintered body that did not use a sintering aid was relatively low.

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

These sintering aids react with the impurity oxygen and Al ₂ O ₃ contained in the AlN raw material powder to form a liquid phase to achieve the densification of the sintered body, and at the same time, to form the impurity oxygen into particles. It is believed to be fixed as a phase phase and to achieve high thermal conductivity.

[0008]

However, in the above conventional manufacturing method, the sintering temperature is 1700 to 1900.
Since the temperature is extremely high, the manufacturing equipment cost including the firing furnace is high, and it is difficult to adopt a continuous manufacturing process. Therefore, an increase in the manufacturing cost of the AlN sintered body and a decrease in mass productivity cannot be avoided. It was a situation. That is, since the sintering temperature is high, a high temperature firing furnace using an expensive graphite (carbon) material having excellent heat resistance as a heat insulating material or a heater material of the firing furnace is essential. However, even if this graphite material is used, there is a problem that the life of the firing furnace is short because it has a large thermal effect, and it is necessary to replace the heat insulating material once every 2-3 years. There was a problem that the cost and maintenance cost became huge. Further, in order to effectively maintain a closed high temperature atmosphere, a batch type (batch type) firing furnace must be adopted, which makes it difficult to introduce a continuous manufacturing process. There was a problem that mass productivity was low.

In order to obtain an AlN sintered body having a particularly high thermal conductivity, the molded body is fired at a high temperature of about 1900 ° C. containing carbon and nitrogen for a long time of 20 to 100 hours, and particles having a thermal resistance are obtained. Since it is necessary to remove the phase phase, the above-mentioned equipment problems and mass production problems become more serious.

In the above conventional manufacturing method, the wettability between AlN and the liquid phase compound is originally low, and the liquid phase itself tends to segregate. Therefore, when the liquid phase solidifies after sintering. The liquid phase remains so as to be unevenly distributed in the interstices of the AlN particles and tends to solidify to form a coarse and brittle grain boundary phase. Further, the grain growth of the crystal grains is likely to proceed, coarse crystal grains having an average grain size of 5 to 10 μm are easily formed, and minute pores do not disappear but remain in the crystal grains, resulting in a dense sintered body. And the final three-point bending strength is 350-400.
There is a problem that only a low-strength aluminum nitride sintered body of about MPa is obtained.

In recent years, the above-mentioned aluminum nitride material having high thermal conductivity (high heat dissipation) is becoming widespread in order to cope with the amount of heat generation that increases with the high integration and high output of semiconductor elements. As for sex, generally satisfactory results have been obtained. However, as described above, the strength as a structural member is insufficient. Therefore, for example, a slight bending stress that acts when mounting a semiconductor substrate formed of an aluminum nitride sintered body on a mounting board or an impact force that acts during handling There is also a problem that the semiconductor substrate is damaged and the manufacturing yield of the semiconductor circuit substrate is significantly reduced.

Further, the AlN sintered body is still insufficient in corrosion resistance to acids and alkalis, and when processed as a semiconductor device material, it is easily damaged by a circuit forming process or an acid cleaning process using an alkaline etching solution. was there. Even when it is used as a structural material, there is a problem that depending on the use environment, oxidation and alkali embrittlement due to chemical substances such as chemicals easily progress, and sufficient durability and reliability cannot be obtained.

The present invention has been made in order to solve the above problems, and in particular, even when it is formed by sintering at a low temperature of 1650 ° C. or lower, the high thermal conductivity inherent to the AlN sintered body is obtained. It is an object of the present invention to provide an AlN sintered body which has the same or higher density as that of a conventional AlN sintered body and which has improved corrosion resistance and mechanical strength, and a manufacturing method thereof.

[0014]

In order to achieve the above object, the inventors of the present invention have variously changed the types and amounts of sintering aids and additives to be added to the raw material aluminum nitride powder, and the sintering temperature. Experimental studies were conducted on the effects of the sintered body on corrosion resistance, density, strength characteristics, and heat transfer characteristics.

As a result, when a small amount of glass frit as an additive is added in addition to the predetermined sintering aid,
An AlN sintered body having significantly improved sinterability and having thermal conductivity, density and strength equal to or higher than those of conventional products and having significantly improved corrosion resistance even at low temperature sintering of 1650 ° C. or lower is obtained. We obtained the finding that we can obtain it. Further, by adding a small amount of glass frit, a protective film made of a glass frit component is formed on the surface of the AlN crystal particles constituting the AlN sintered body, and the corrosion resistance of the AlN sintered body is greatly improved. It is considered that the interfacial bonding strength between them is increased and an AlN sintered body having excellent mechanical strength characteristics can be obtained. The present invention has been completed based on the above findings.

That is, the first aluminum nitride sintered body according to the present invention is an aluminum nitride sintered body obtained by firing at a low temperature of 1650 ° C. or lower, and at least one element selected from Group IIIa elements of the periodic table. Oxide of 0.5 to 7% by weight, calcium oxide of 0.5 to 3% by weight, aluminum oxide of 1.5% by weight or less, glass frit of 0.2 to 1% by weight, and manganese oxide of , 0.5% by weight or less of at least one selected from chromium oxide, zirconium oxide, strontium oxide and titanium oxide, 1% by weight or less of tungsten in terms of oxide, and the balance aluminum nitride. Is characterized by.

The second aluminum nitride sintered body according to the present invention is an aluminum nitride sintered body obtained by firing at a low temperature of 1650 ° C. or lower, and at least one element selected from Group IIIa elements of the periodic table. 0.5 to 5% by weight of oxide
And at least one selected from Ca, Sr and Ba
0.1 to 1% by weight of oxides of seed elements, 1 to 3% by weight of calcium tungstate, 1.5% by weight or less of aluminum oxide, and 0.2 to 1% by weight of glass frit, Manganese oxide, chromium oxide, zirconium oxide,
It is characterized in that at least one selected from strontium oxide and titanium oxide is 0.5 wt% or less and the balance is aluminum nitride.

The glass frit is at least one selected from borosilicate glass, aluminoborosilicate glass, 96% quartz glass, soda lime glass, lead glass, aluminosilicate glass and special glass.
As the special glass, crystallized glass and alkali resistant glass are suitable.

The content of impurity cations such as Fe and Mg is preferably 0.2% by weight or less. Especially Mg is AlN
Care must be taken because a spinel compound having a high thermal resistance is formed in the structure to easily reduce the thermal conductivity of the sintered body. Further, the average crystal grain size of the sintered body is preferably in the range of 1 to 4 μm. The AlN sintered body having the above composition has a thermal conductivity of 11
0 W / (m · K) or more, and when the sintered body is immersed in a 10% hydrochloric acid (HCl) solution at room temperature (25 ° C.) for 24 hours, the weight loss of the sintered body before and after the immersion is reduced. ,
Compared with the conventional one, it is 1/3 or less and the sintered body is 1
In a 0% strength caustic soda (NaOH) solution at room temperature (25
When it is immersed for 24 hours at (° C.), the weight loss of the sintered body before and after the immersion is 1/2 or less as compared with the conventional one, and thus excellent corrosion resistance against acid and alkali is exhibited.

In the first method for producing an aluminum nitride sintered body according to the present invention, the aluminum nitride raw material powder contains 0.5 to 0.5% of an oxide of at least one element selected from Group IIIa elements of the periodic table. 7% by weight and calcium oxide of 0.
5 to 3% by weight, aluminum oxide to 1.5% by weight or less, glass frit to 0.2 to 1% by weight, and at least 1 selected from manganese oxide, chromium oxide, zirconium oxide, strontium oxide and titanium oxide. A raw material mixture containing 0.5% by weight or less of a seed and 1% by weight or less of tungsten in terms of oxide is molded, and the obtained molded product is heated at a low temperature of 1650 ° C. or lower in a non-oxidizing atmosphere. It is characterized by being sintered.

In the second method for producing an aluminum nitride sintered body according to the present invention, 0.5 to 0.5 of an oxide of at least one element selected from Group IIIa elements of the periodic table is added to the aluminum nitride raw material powder. 5% by weight, calcium tungstate 1 to 3% by weight, aluminum oxide 1.5% by weight or less, glass frit 0.2 to 1% by weight, manganese oxide, chromium oxide, zirconium oxide, strontium oxide. And at least one selected from titanium oxide
A raw material mixture containing 0.5% by weight or less of a seed is formed, and the obtained formed body is sintered at a low temperature of 1650 ° C. or less in a non-oxidizing atmosphere.

The aluminum nitride (AlN) raw material powder used in the method of the present invention, which is the main component of the sintered body, includes:
Considering sinterability and thermal conductivity, the content of impurity oxygen is suppressed to 1.3 wt% or less, and the average particle size is 0.5 to
Fine AlN of about 2 μm, preferably 1.5 μm or less
Powder may be used.

The oxide of the group IIIa element of the periodic table (long period type) acts as a sintering aid, and in order to make the AlN sintered body dense, 0.5 to 7 relative to the AlN raw material powder. It is added in the range of weight%. As specific examples of the above-mentioned sintering aid, oxides of rare earth elements (Y, Sc, Ce, Dy, etc.) or substances which become these compounds by the sintering operation are used, and particularly yttrium oxide (Y ₂ O ₃ ) Is preferred. If the amount of the sintering aid added is less than 0.5% by weight, the effect of improving the sinterability is not sufficiently exerted, the sintered body is not densified, and a low-strength sintered body is formed. , Oxygen is solid-dissolved in the AlN crystal, and a sintered body having high thermal conductivity cannot be formed. On the other hand, if the addition amount exceeds 7% by weight, not only the effect as a sintering aid reaches a saturated state and becomes meaningless, but also the thermal conductivity of the AlN sintered body obtained by sintering is rather increased. While decreasing, the grain boundary phase remains in the sintered body in a large amount, and the volume of the grain boundary phase removed by heat treatment is large, so pores remain in the sintered body and the shrinkage rate increases. , Easily deformed. In addition, in order to obtain a high-density sintered body, it is necessary to set the sintering temperature high, which makes the heat-resistant specifications of the components of the firing furnace more sophisticated and makes continuous firing operation difficult. Manufacturing cost and mass productivity are reduced. The more preferable addition amount of the group IIIa element oxide is 1 to 2% by weight.

The addition amount of the Group IIIa element oxide in the second aluminum nitride sintered body is in the range of 0.5 to 5% by weight, more preferably 1%, in consideration of the addition amount of other components. It is set in the range of up to 2% by weight.

While the glass frit lowers the sintering temperature to improve the sinterability, it forms a protective film on the surface of the AlN crystal grains constituting the AlN sintered body, thereby significantly improving the corrosion resistance of the AlN sintered body. At the same time, it is an effective component for increasing the interfacial bonding strength between AlN crystal grains and increasing the mechanical strength.

As a specific example of the above glass frit, synthetic glass powder having a chemical composition as shown by symbols A to I in Table 1 below is suitable.

[0027]

[Table 1]

Each of the glass frits is synthetically produced by melting a mixed powder adjusted to a predetermined chemical composition in air at a temperature of about 1500 ° C. and then finely pulverizing a solidified body which is cooled and solidified. The particle size of the glass frit may be adjusted to around 1 μm.

The above glass frit is added to the AlN sintered body in the range of 0.2 to 1% by weight. If the amount of glass frit added is less than 0.2% by weight, the effect of reducing the sintering temperature and the effect of improving corrosion resistance and strength will be insufficient.
On the other hand, if the amount added is too large, exceeding 1% by weight, Al
Since the thermal conductivity of the N sintered body decreases, the addition amount is set within the above range, but the range of 0.2 to 0.5% by weight is more preferable.

Calcium oxide (CaO) is a component that can more effectively lower the sintering temperature and improve the sinterability, especially when it is added in combination with the oxide of the group IIIa element and WO _3. It is added in the range of 0.5 to 3% by weight. If the addition amount is too small, less than 0.5% by weight, the effect of improving the sinterability is small. On the other hand, if the addition amount exceeds 3% by weight, the corrosion resistance of the sintered body against acids and alkalis decreases, and the thermal conductivity decreases, so that the sintering temperature must be set high in order to obtain a certain density. Occurs. Therefore, the addition amount is set within the above range, but the range of 0.5 to 1.5% by weight is more preferable.

Aluminum oxide (Al ₂ O ₃ ) has the effect of lowering the sintering temperature and improving the fracture toughness value of the AlN sintered body. The content of Al ₂ O ₃ is 1.5% by weight or less. Adjusted to the range of. If the content of Al ₂ O ₃ exceeds 1.5% by weight, the thermal conductivity of the sintered body will decrease. The more preferable content of Al ₂ O ₃ is 1% by weight or less. The Al ₂ O ₃ component may be added separately as an additive, by adding Al ₂ O ₃ generated by oxidation during pulverization of the AlN raw material, or by adding the AlN raw material powder in an oxygen-containing atmosphere. Alternatively, a method may be used in which the Al ₂ O ₃ component generated by surface oxidation is added after heating with.

Manganese oxide (MnO), chromium oxide (C
r ₂ O ₃ ), zirconium oxide (ZrO ₂ ), strontium oxide (SrO) and titanium oxide (TiO ₂ ).
Is also effective for lowering the sintering temperature and improving the sinterability, and is added in the range of 0.5 wt% or less. If the added amount exceeds 0.5% by weight, the thermal conductivity of the AlN sintered body is lowered like other impurities.

Tungsten oxide such as WO ₃ is a component that can more effectively lower the sintering temperature and improve the sinterability, especially when it is added together with calcium oxide (CaO). In the bound body, it is added in the range of 1% by weight or less. When the amount added is too large, more than 1% by weight, the thermal conductivity of the AlN sintered body is lowered like other impurities.

In place of calcium oxide (CaO) and tungsten oxide (WO ₃ ) added in the first AlN sintered body, calcium tungstate (Ca) is used.
The material to which WO ₄ ) is added is the second AlN sintered body.
As described above, the combined effect of adding CaO and WO ₃ makes the effect of reducing the sintering temperature particularly remarkable. In this case C
The addition amount of aWO ₄ is set in the range of 1 to 3% by weight.
If the addition amount is less than 1% by weight, the effect of reducing the sintering temperature is small. On the other hand, if it exceeds 3% by weight, the thermal conductivity of the AlN sintered body will decrease.

Impurity cations such as Fe and Mg are Al
Since it is easy to form a compound that inhibits the heat conduction of the N sintered body,
The content in the AlN sintered body is set to 0.2% by weight or less.

The above AlN raw material powder, various sintering aids and glass frit components are put into a pulverizing mixer such as a ball mill and mixed for a predetermined time to form a uniform raw material mixture. Next, the obtained raw material mixture is filled in a mold having a predetermined shape and pressure-molded to form a molded body. At this time, by adding 5 to 10% by weight of an organic binder such as paraffin and stearic acid to the raw material mixture in advance,
The molding operation can be carried out smoothly.

As a forming method, a general-purpose die pressing method, a slurry casting method, a hydrostatic pressing method, or a sheet forming method such as a doctor blade method can be applied.

Subsequent to the above molding operation, the molded body is heated to 400 to 550 ° C. in air or in a non-oxidizing atmosphere such as a nitrogen gas atmosphere at a temperature of 400 to 800.
By heating to 0 ° C., the previously added organic binder is thoroughly degreased and removed.

Next, a plurality of sheet-shaped compacts that have been degreased are laminated in multiple stages in a firing furnace through a sieving powder made of, for example, ceramics sintered powder, and the plurality of compacts are collectively packaged in this arrangement state. And sintered at a predetermined temperature. For the sintering operation, the molded body was 1650 in a non-oxidizing atmosphere such as nitrogen gas.
It is carried out by heating at a low temperature of ℃ or less for about 2 to 10 hours. Especially by adding a glass frit component,
It becomes possible to sinter at a temperature of 500 to 1650 ° C., which is much lower than the conventional temperature.

The sintering atmosphere may be a non-oxidizing atmosphere that does not react with AlN, but is usually a nitrogen gas or a reducing atmosphere containing nitrogen gas. H as reducing gas
You may use ₂ gas and CO gas. The sintering may be performed in an atmosphere of various pressure conditions including vacuum (including a slight reducing atmosphere), reduced pressure, pressurization and normal pressure.

When fired at a low temperature such that the sintering temperature is less than 1500 ° C., although it depends on the particle size of the raw material powder and the amount of oxygen contained, it is difficult to densify and there are difficulties in properties such as strength and thermal conductivity. Is likely to occur.

On the other hand, when firing at a high temperature exceeding 1650 ° C., it is necessary to set the heat resistance specification of the firing furnace to a higher temperature side, the manufacturing equipment becomes expensive, and it becomes difficult to adopt a continuous manufacturing process. . Therefore, the sintering temperature is 15
It is set in the range of 00 to 1650 ° C.

Then, a raw material mixture having a predetermined composition in which a sintering aid and a glass frit are added to the above AlN raw material powder is molded, degreased and sintered under the above conditions to obtain 1
Even if it is fired at a low temperature of 650 ° C or lower, it has a dense crystal structure with excellent corrosion resistance and a thermal conductivity of 110 W / (m ·
A high-strength AlN sintered body having a temperature of K) or higher is obtained.

[0044]

According to the aluminum nitride sintered body and the method for producing the same having the above-described structure, a predetermined amount of glass frit is added together with a sintering aid or additive made of an oxide of a group IIIa element of the periodic table. Since it is an AlN sintered body, the sinterability is significantly improved, and an AlN sintered body having the same or higher thermal conductivity, density and strength as the conventional example can be obtained even at low temperature sintering of 1650 ° C or lower. To be In particular, since it becomes possible to perform firing at a low temperature of 1650 ° C. or lower, it is not necessary to use an expensive firing furnace with high temperature specifications, and an AlN sintered body can be used using an ordinary firing furnace that uses an inexpensive heat insulating material. Can be continuously manufactured. Therefore, the manufacturing cost and mass productivity of the AlN sintered body can be dramatically improved.

Further, by adding glass frit, a protective film made of a glass frit component is formed on the surface of the AlN crystal particles constituting the AlN sintered body, which protects against acid and alkali.
The corrosion resistance of the AlN sintered body is greatly improved. Further, the above-mentioned coating enhances the interfacial bonding strength between the AlN crystal particles, so that a high-strength and dense crystal structure can be obtained. Therefore, it is possible to obtain an aluminum nitride sintered body which has the original high thermal conductivity of the aluminum nitride sintered body and is excellent in corrosion resistance and strength characteristics.

[0046]

EXAMPLES Next, the aluminum nitride sintered body according to the present invention will be described more specifically with reference to the following examples.

Examples 1 to 21 Oxygen was added as an impurity in an amount of 0.8% by weight, and the average particle size was 1 μ
added to aluminum nitride powder of m, Table 2 and Table 3 glass frit, as shown in component and Y ₂ O ₃ as a sintering _{aid, CeO, WO 3, TiO 2} , ZrO 2, Al
₂ O ₃ , MnO, Cr ₂ O ₃ , CaO, SrO, Nd ₂
A predetermined amount of each O ₃ was added, and the mixture was mixed in a ball mill for 20 hours using ethyl alcohol as a solvent to prepare a raw material mixture. The types of glass frit used had the compositions shown by symbols A to I in Table 1. Next, 5.5% 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 compression-molded in a uniaxial direction with a pressing force of 1200 kg / cm ² , to obtain a length of 50 mm × width of 50 mm × thickness. A large number of 5 mm square plate-shaped compacts were prepared. Subsequently, each molded body was heated in an air atmosphere at 450 ° C. for 1 hour to be degreased.

Next, the degreased compacts were housed in an AlN firing container and densified and sintered at a sintering temperature of 1525 to 1650 ° C. shown in Tables 2 and 3 for 4 hours in a firing furnace. Then, the AlN sintered bodies according to Examples 1 to 21 were manufactured by cooling at a cooling rate of 200 ° C./hr.

Comparative Example 1 On the other hand, a sintering aid (Y ₂ O ₃ ) made of a Group IIIa element oxide without adding glass frit, CaO and WO ₃ at all.
A raw material was prepared, molded, degreased, and sintered under the same conditions as in Example 3 except that only Al was added and the mixture was sintered at 1780 ° C. to produce an AlN sintered body according to Comparative Example 1 having the same dimensions.

Comparative Example 2 Preparation of raw materials under the same conditions as in Example 10 except that the glass frit and WO ₃ were not added at all, the sintering aid (Y ₂ O ₃ ) and CaO were added, and sintering was performed at 1680 ° C. According to Comparative Example 2 having the same dimensions after molding, degreasing and sintering
An N sintered body was manufactured.

Comparative Example 3 3% by weight of Y ₂ O ₃ , without adding glass frit,
Comparison having the same dimensions after raw material preparation, molding, degreasing and sintering under the same conditions as in Example 2 except that 1% by weight of CaO and 1% by weight of Al ₂ O ₃ were added and sintered at 1680 ° C. An AlN sintered body according to Example 3 was manufactured.

Comparative Example 4 Preparation of raw materials, molding, degreasing under the same conditions as in Example 10 except that an excessive amount (4% by weight) of CaO was added and that Cr ₂ O ₃ was not added and sintering was performed at 1700 ° C. The aluminum nitride sintered body according to Comparative Example 4 having the same dimensions was manufactured by sintering.

[0054] Comparative Example 5 also excess Al ₂ O _{3 (2} wt%), except that the addition to produce an AlN sintered body according to Comparative Example 5 was treated under the same conditions as in Example 1.

Comparative Example 6 Further , an excessive amount (2% by weight) of glass frit was added, and 1
An AlN sintered body according to Comparative Example 6 was manufactured by treating under the same conditions as in Example 1 except that sintering was performed at 500 ° C.

[0056] was added MnO in excess in place of Comparative Example 7 Al ₂ O ₃ (1 wt%), AlN according to Comparative Example 7 was treated under the same conditions as in Example 1, except that the sintered at 1600 ° C. A sintered body was manufactured.

Comparative Example 8 Comparative Example 8 was carried out in the same manner as in Example 1 except that Y ₂ O ₃ as a sintering aid was added in an excessive amount (10% by weight) and was sintered at 1725 ° C. An AlN sintered body was manufactured.

Comparative Example 9 CaO was not added at all, and 3% by weight of Y ₂ was used as a sintering aid.
1% by weight of Al ₂ O ₃ in addition to O ₃ and 170
An AlN sintered body according to Comparative Example 9 was manufactured by performing the same process as in Example 3 except that sintering was performed at 0 ° C.

Comparative Example 10 No addition of Group IIIa element oxide as a sintering aid was performed, and 1
An AlN sintered body according to Comparative Example 10 was manufactured by performing the same process as in Example 5 except that sintering was performed at 750 ° C.

Of the above Comparative Examples 1 to 10, Comparative Example 1
4 and Comparative Examples 8 to 10 were heated to a temperature of 1600 ° C. and densified and sintered for 4 hours.
Since neither of them was sufficiently densified, the sintering temperature was raised to the sintering temperature shown in Table 3 to carry out the densification sintering.

In order to evaluate the strength characteristics and heat dissipation characteristics of the AlN sintered bodies according to Examples 1 to 21 and Comparative Examples 1 to 10 thus obtained, the density and thermal conductivity corresponding to the strength of each sample were measured. The measurement was performed, and the results shown in Tables 2 and 3 below were obtained.

[0062]

[Table 2]

[0063]

[Table 3]

As is clear from the results shown in Tables 2 and 3, Examples 1 to 21 in which a glass frit component was added in a small amount in addition to a sintering aid such as Y ₂ O ₃ or CaO
It was found that the AlN sintered body according to (1) had a dense and fine crystal structure, and was excellent in both density and thermal conductivity, despite being manufactured by low temperature sintering at 1650 ° C. or lower. By the way, the density is 3.25 to 3.38, which is equal to or higher than the conventional one, and the thermal conductivity is 118 to 145 W /
It was confirmed that it was excellent as (m · K).

Further, in order to evaluate the corrosion resistance of each sintered body from the two aspects of acid resistance and alkali resistance, the following immersion test was carried out. That is, each sintered body was immersed in a 10% aqueous solution of hydrochloric acid (HCl) at room temperature (25 ° C.) for 24 hours, and the weight loss per unit area due to oxidative corrosion of the sintered body before and after the immersion was measured. Also, the sintered body is 10%
Concentrated caustic soda (NaOH) solution at room temperature (25
C.) for 24 hours, and the weight loss per unit area due to alkali corrosion of the sintered body before and after the immersion was measured.

As a result, in the AlN sintered bodies according to the respective examples, the weight loss due to hydrochloric acid was 1.5 mg / cm 3.
^{It was 2} or less, which was 1/3 or less as compared with the conventional AlN sintered bodies shown in Comparative Examples 1 to 3, and showed excellent acid resistance.
In addition, the weight loss due to caustic soda is 50 mg / cm ²
It was below, which was 1/2 or less as compared with the conventional AlN sintered body, and it was proved that good alkali resistance was exhibited.

On the other hand, the AlN sintered bodies according to Comparative Examples 1 to 3 to which no glass frit is added cannot be densified by low temperature firing at 1650 ° C. or lower, and high temperature firing at 1680 to 1780 ° C. is required. The effect of reducing the facility cost and improving the mass productivity by the low temperature firing, which is the object of the invention, cannot be obtained.
Further, the AlN sintered body according to Comparative Example 4 in which CaO is added in an excessive amount of 4% by weight also requires high temperature firing at 1700 ° C. or higher. Further, in the sample of Comparative Example 5 in which an excessive amount of Al ₂ O ₃ was added, low temperature firing was possible, but the thermal conductivity markedly decreased.

Further, in the sample of Comparative Example 6 in which the glass frit was added in an excessive amount, the thermal conductivity became insufficient, and Mn
In the sample of Comparative Example 7 in which O was added in an excessive amount, the thermal conductivity was further deteriorated. Further, in the sample of Comparative Example 8 in which Y ₂ O ₃ as a sintering aid was added in an excessive amount of 10% by weight, high temperature sintering at 1700 ° C. or higher was required in spite of the addition of the glass frit, It was confirmed that the alkali corrosion resistance was lowered.

Further, it was found that the AlN sintered body according to Comparative Example 9 in which no CaO as a sintering aid was added needed to be fired at a high temperature of 1700 ° C. or higher. In addition, in the AlN sintered body according to Comparative Example 10 in which no group IIIa element oxide was added, high temperature firing at 1750 ° C. or higher was necessary despite addition of CaO and WO ₃ and addition of glass frit. It was found that the corrosion caused by the addition of CaO increased rapidly. Similarly, in the AlN sintered body according to Comparative Example 4 in which CaO is added in an excessive amount, 1700
It was confirmed that a high temperature baking of ℃ or more was required and the alkali corrosion resistance was lowered.

On the other hand, according to the manufacturing method of the AlN sintered body according to each example, since the glass frit is mixed in the raw material powder, even in the case of low temperature sintering of about 1525 to 1650 ° C. A dense, high-strength, high thermal conductivity, and high corrosion resistance AlN sintered body was obtained. Therefore, continuous operation is possible without using a high-temperature firing furnace, and using a firing furnace composed of ordinary inexpensive heat-resistant parts.
It has become possible to significantly improve the manufacturing cost and mass productivity of the N sintered body.

Further, in Tables 2 and 3, Example 1,
As is clear from the results shown in _{2, 3} , 7, 14, 16, 19, and 21, CaO, Al ₂ O ₃ , and Mn were added in addition to the Group IIIa element oxide and the glass frit as the sintering aid.
O, ZrO ₂ , Cr ₂ O ₃ , SrO, WO ₃ , TiO ₂
Sintering temperature of 1525 to
It became possible to lower the temperature to about 1625 ° C., and it was proved that the relaxation of the manufacturing conditions by the low temperature sintering was realized more effectively.

When the surface of each AlN sintered body according to Examples 1 to 21 was observed with a scanning electron microscope (SEM), the grain boundary phase was uniformly dispersed around the fine AlN crystal grains. It was also confirmed that a protective film made of a glass frit component was formed on the surface of the AlN crystal particles. On the other hand, in the sintered bodies according to Comparative Examples 1 to 3, since the effect of improving the sinterability by adding the glass frit is small, the AlN particles themselves are also coarse, and the coarse grain boundary phase is present around the adjacent AlN particles. It was formed to be aggregated.

[0073]

As described above, according to the aluminum nitride sintered body and the manufacturing method thereof according to the present invention, the periodic table II
Since a predetermined amount of glass frit is added together with sintering aids and additives consisting of oxides of Group Ia elements to form an AlN sintered body, the sinterability is greatly improved, and low temperature firing at 1650 ° C or lower is performed. Even with the consolidation, an AlN sintered body having the same or higher thermal conductivity, density and strength as the conventional example can be obtained. In particular, since it becomes possible to perform firing at a low temperature of 1650 ° C. or lower, it is not necessary to use an expensive firing furnace with high temperature specifications, and an AlN sintered body can be used using an ordinary firing furnace that uses an inexpensive heat insulating material. Can be continuously manufactured. Therefore, the manufacturing cost and mass productivity of the AlN sintered body can be dramatically improved.

Further, by adding glass frit, a protective film made of a glass frit component is formed on the surface of the AlN crystal particles constituting the AlN sintered body, which protects against acid and alkali.
The corrosion resistance of the AlN sintered body is greatly improved. Further, the above-mentioned coating enhances the interfacial bonding strength between the AlN crystal particles, so that a high-strength and dense crystal structure can be obtained. Therefore, it is possible to obtain an aluminum nitride sintered body which has the original high thermal conductivity of the aluminum nitride sintered body and is excellent in corrosion resistance and strength characteristics.

Claims (7)

[Claims] 1. An aluminum nitride sintered body obtained by firing at a low temperature of 1650 ° C. or lower, wherein 0.5 to 7% by weight of an oxide of at least one element selected from Group IIIa elements of the periodic table, From 0.5 to 3% by weight of calcium oxide, 1.5% by weight or less of aluminum oxide, 0.2 to 1% by weight of glass frit, and from manganese oxide, chromium oxide, zirconium oxide, strontium oxide and titanium oxide. An aluminum nitride sintered body comprising at least 0.5% by weight or less of selected one, 1% by weight or less of tungsten in terms of oxide, and aluminum nitride constituting the balance. 2. An aluminum nitride sintered body obtained by firing at a low temperature of 1650 ° C. or lower, containing 0.5 to 5% by weight of an oxide of at least one element selected from Group IIIa elements of the periodic table, 1-3% by weight of calcium tungstate,
Aluminum oxide 1.5% by weight or less, glass frit 0.2 to 1% by weight, manganese oxide, chromium oxide,
An aluminum nitride sintered body, which comprises 0.5% by weight or less of at least one selected from zirconium oxide, strontium oxide and titanium oxide, and the balance aluminum nitride. 3. The aluminum nitride sintered body according to claim 1, which has a thermal conductivity of 110 W / (m · K) or more. 4. The glass frit is borosilicate glass,
The aluminum nitride sintered body according to claim 1 or 2, which is at least one selected from aluminoborosilicate glass, 96% quartz glass, soda-lime glass, lead glass, aluminosilicate glass and special glass. . 5. A periodic table is added to aluminum nitride raw material powder.
An oxide of at least one element selected from Group IIIa elements is 0.5 to 7% by weight, and calcium oxide is 0.5 to 3%.
% By weight, 1.5% by weight or less of aluminum oxide, 0.2 to 1% by weight of glass frit, and at least one selected from manganese oxide, chromium oxide, zirconium oxide, strontium oxide and titanium oxide. 0.5% by weight or less and 1% by weight or less of tungsten in terms of oxide are added to form a raw material mixture, and the obtained formed body is sintered at a low temperature of 1650 ° C. or lower in a non-oxidizing atmosphere. A method for manufacturing an aluminum nitride sintered body, comprising: 6. The aluminum nitride raw material powder is added to the periodic table.
0.5 to 5% by weight of an oxide of at least one element selected from Group IIIa elements, 1 to 3% by weight of calcium tungstate, 1.5% by weight or less of aluminum oxide, and a glass frit. A raw material mixture obtained by adding 0.2 to 1% by weight and 0.5% by weight or less of at least one selected from manganese oxide, chromium oxide, zirconium oxide, strontium oxide and titanium oxide is obtained. A method for producing an aluminum nitride sintered body, comprising sintering the formed body at a low temperature of 1650 ° C. or lower in a non-oxidizing atmosphere. 7. The method for producing an aluminum nitride sintered body according to claim 5, wherein the oxygen content of the aluminum nitride raw material powder is set to 1.3% by weight or less.