JP2807430B2 - Aluminum nitride sintered body and method for producing the same - Google Patents

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 and a method for producing the same, and more particularly, to a method of compacting by low-temperature sintering, easy glass sealing and copper metallization, and a high resistance. The present invention relates to an aluminum nitride sintered body having a bending strength and a method for manufacturing the same.

[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, required characteristics of circuit boards, semiconductor packages, and the like have become more severe. For example, high thermal conductivity is required in order to efficiently dissipate heat generated from a semiconductor element, and the coefficient of thermal expansion of the semiconductor element is reduced in order to minimize the risk of breakage of the semiconductor element due to thermal stress. It is required to be close to that of the above and to have high strength.

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, alumina ceramics have higher thermal conductivity than conventional plastic and glass materials, but have insufficient thermal conductivity of about 20 W / m K,
The coefficient of thermal expansion is 7 × 10 ^-6 / K and the coefficient of thermal expansion of silicon (4.5 ×
10 ^-6 / K), which is not enough to support high integration and high speed of semiconductor devices.

[0004] For these reasons, attention has been paid to aluminum nitride (AlN) sintered bodies in place of alumina ceramics, and applications of multilayered circuit boards to insulating materials and the like have been studied in various fields. AlN sintered body has a thermal expansion coefficient of 4.0 × 10 ^-6 / K
As the thermal expansion coefficient of silicon is almost equal to that of silicon, the thermal stress of the semiconductor element can be reduced sufficiently, and it has high thermal conductivity. You can do it. However, aluminum nitride has a strong covalent bond and is a difficult-to-sinter material, so a sintering temperature of about 2073K was required to obtain a dense sintered body.

[0005] In the future, cost reduction is urgently needed in order to expand applications of the AlN sintered body, and low-temperature sintering is being studied as an attempt to realize the use of an existing continuous furnace. As a result of recent research and development, it has become possible to lower the sintering temperature to a temperature of about 1873 K without using an ultrafine AlN powder or the like by improving the AlN sintering aid.

On the other hand, when used as a semiconductor package or the like, it is necessary to consider the glass sealing property of the AlN sintered body, and when used as a circuit board or the like, it is necessary to consider the copper metallizing property of the AlN sintered body. is there. That is, when the AlN sintered body is used for a package material such as a QFP (quad flood package), after mounting the semiconductor element, glass sealing using a cap may be performed to protect the element. It is desired that the glass sealing property is good. Similarly, when a circuit is formed on an AlN sintered body, it is desired that general copper metallization can be easily applied.

[0007]

By the way, the conventional Al
As a low-temperature sintering technique for an N sintered body, for example, a method of simultaneously adding a rare earth element compound and an alkaline earth oxide (see JP-A-61-117160) has been proposed. However, sintering is possible even at 1973K or lower, but good glass sealing properties cannot be obtained because no components necessary for glass sealing exist on the surface.

Further, for the purpose of low-temperature sintering, high-density, high thermal conductivity, etc. of the AlN sintered body, group 4A of the periodic table,
A method of adding at least one selected from transition metal elements of Group 5A, 6A, 7A and 8A (Japanese Patent Application Laid-Open No.
According to this method, densification is possible even at a sintering temperature of 1873 to 1923K,
It is expected that the glass sealing property is inferior, glazing is difficult, and copper metallization is also difficult. further,
A method of simultaneously adding an oxide of a Group 2A element and a rare earth metal of the periodic table, and B and a transition metal (see Japanese Patent Application Laid-Open No. 2-130064) has also been proposed, but also has a good glass sealing property. It is considered difficult to obtain an AlN sintered body.

As described above, in the conventional AlN sintered body, after achieving high density and good thermal conductivity as compared with alumina by low-temperature sintering, glass sealing property, copper metallizing property, and bending It has been an issue to improve the strength and the like.

[0010] The present invention has been made to address such problems, and can be densified at a temperature of about 1673 to 1873 K, has better thermal conductivity than alumina, Another object of the present invention is to provide an aluminum nitride sintered body having good glass sealing properties, copper metallizing properties, and bending strength, and a method for producing the same.

[0011]

Means for Solving the Problems The present inventors have developed 1673-1
It can be densified by firing at a low temperature of about 873K, does not exude a large amount of auxiliary components on the surface of the sintered body, and easily uses glass without lowering the thermal conductivity to the same level as alumina. Can be sealed, easy to glaze,
Further, in order to provide an aluminum nitride sintered body having an easy copper metallization and a high bending strength, various studies were made on the types and amounts of additives to aluminum nitride. It has been found that the above object can be achieved by adding a simple substance or a compound of an element, an Al element, a group 3A element and a group 2A element of the periodic table in a total range of 20% by weight or more and 65% by weight or less.

The present invention has been made based on such findings, and the aluminum nitride sintered body of the present invention has
And a component comprising a B element, an O element, a Si element, an Al element, a Group 3A element and a Group 2A element of the periodic table, wherein the component is 20 to 65.
%, And the composition ratio of the B element, Si element, O element, 3A element and 2A element in the composition is (3A element): (2A element): (oxygen):
(Boron): (silicon) = (16-31): (4-10): (9-1)
7): (0.4 to 1.6): (0.3 to 1.2) and thermal conductivity of 4
It is characterized by being 0 to 80 W / m K.

Further, the method for producing an aluminum nitride sintered body of the present invention is characterized in that the AlN powder contains at least a Β element, a Si element, an O element, a simple substance or a compound of a group 3A element and a group 2A element of the periodic table, The composition ratio of the above elements based on the main starting material of each element is (3A element): (2A element): (oxygen): (boron): (silicon) = (16 to 31): (4
To 10): (9 to 17): (0.4 to 1.6): a step of adding a total of 20 to 65% by weight while satisfying (0.3 to 1.2) to prepare a sintered body raw material; Baking the raw material of the sintered body at a temperature of 1673 to 1873K.

The AlN sintered body of the present invention comprises a component (subcomponent) composed of a B element, an O element, a Si element, an Al element, a Group 3A element and a Group 2A element of the periodic table as a grain boundary phase component or the like. ) In an amount of from 20 to 65% by weight, and the sub-component is an aluminate compound containing at least one of a Group 3A element and a Group 2A element of the periodic table, a single B element or a compound containing a B element (For example, an Al borate compound or a rare earth borate compound), and a Si element alone or a compound containing a Si element. These sub-components function as components that enable low-temperature sintering of the AlN sintered body during sintering, and contribute to improvement in glass sealing properties, copper metallization properties, and bending strength after sintering. I do.

If the amount of sub-components in the AlN sintered body is less than 20% by weight, the sub-component phases occupying the surface of the AlN sintered body, mainly oxides such as aluminate compounds of Group 3A element and Group 2A element, Further, the area occupied by the Al borate compound or the rare earth borate compound decreases. Oxide and borate compounds usually present in the grain boundary phase have good wettability with glass and effectively act for sealing the glass, but when the abundance on the surface of the sintered body is small, glaze occurs. Or glass sealing cannot be performed easily, and further, copper metallization cannot be performed favorably. In other words, it is necessary to always form a layer having good wettability of glass by an oxidation step of the AlN sintered body. The amount of the sub-component is more preferably 40% by weight or more, and 50% by weight in consideration of the glass sealing property.
% Or more is desirable.

On the other hand, when the amount of sub-components in the AlN sintered body exceeds 65% by weight, the microstructure of the sintered body changes, and specifically, the high thermal conductive AlN crystal grains are separated from the adjacent AlN crystal grains. There is no contact on a large surface, and the thermal conductivity is almost the same as that of Al ₂ O ₃ , and the advantage of using AlN, which is characterized by high thermal conductivity, is lost. Further, a large amount of the auxiliary component oozes out on the surface of the sintered body, thereby impairing the surface smoothness and the like.

[0017] Then, the element {Si, Si
The element, O element, simple substance or compound of Group 3A element and Group 2A element of the periodic table, and the compositional ratio (weight ratio) of the element based on the main starting material of each element (Group 3A element): (2
Group A element): (oxygen): (boron): (silicon) = (16-3)
1): (4 to 10): (9 to 17): (0.4 to 1.6): Densification by low-temperature sintering by using a sintered body material added to AlN powder satisfying (0.3 to 1.2) Can be realized with good reproducibility. In other words, the composition ratio of the Β element, the Si element, the O element, the group 3A element and the group 2A element in the periodic table in the sub-component in the AlN sintered body of the present invention is expressed by (group 3A element) :( group 2A element) ): (Oxygen): (boron): (silicon)
= (16-31): (4-10): (9-17): (0.4-1.6): (0.3
-1.2), a dense sintered body can be obtained with low temperature sintering with good reproducibility.

It is preferable that the composition ratio of each of the above elements in the sub-structure in the AlN sintered body is a composition ratio of the element based on the main starting material of each element. The amounts of the main starting materials of the respective elements referred to here are, for example, the group 3A element and the group 2A element, which do not include the group 3A element and the group 2A element when the 添加 element is added as a compound with these elements. For oxygen, AlN
It is the sum of the amount of oxygen contained therein and the amount of oxygen in alumina, and does not include the amount of oxygen when a Group 3A element, a Group 2A element, or a Si element is added as an oxide.

When the AlN sintered body of the present invention is used as a circuit board or the like, it is preferable to color the sintered body uniformly. As the coloring agent, 4A group, 5A group,
Group 6A elements are effective.
When it is contained in the range of 0.9% by weight, uniform coloring can be achieved.

Thus, B element, Si element, O element,
An AlN sintered body containing an Al element, a subcomponent consisting of a Group 3A element and a Group 2A element of the periodic table in the range of 20 to 65% by weight is densified by low-temperature sintering at about 1673 to 1873K (for example,
3.29 ~ 3.40g / cm ³ ), good thermal conductivity compared with alumina of 40 ~ 80W / m K, good glass sealing property, copper metallizing property, and good bending strength Is obtained.

[0021]

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. A used for producing the AlN sintered body of the present invention
The 1N powder preferably has an average particle size in the range of 0.02 to 1.0 μm and an impurity oxygen content in the range of 0.6 to 2% by weight. Other than these, there is no particular limitation. AlN powder having an average particle size of 0.02 to 1.0 μm contributes to densification in low-temperature sintering. A more preferred average particle size is in the range of 0.04 to 0.8 μm. In addition, ultra-fine powder of 0.1 μm or less is difficult to handle and may have a large amount of impurity oxygen.
It is preferable to use AlN powder of 0.3 to 0.7 μm.

The oxygen contained in the Α1N powder is Al
It contributes to the sintering of N. If the amount of oxygen is less than 0.6% by weight, the sinterability of Al 低下 decreases, while the amount of oxygen decreases by 2%.
It exceeds wt% thermal conductivity is lowered to the same level as Al ₂ Ο _3, achievement of 40W / m K or more thermal conductivity becomes difficult. The oxygen content of the AlN powder is more preferably in the range of 0.7 to 1.5% by weight, and preferably in the range of 0.8 to 1.3% by weight.

In the AlN powder as described above, at least Β element, Si element, O element, simple substance or compound of group 3A element and group 2A element of the periodic table in a total amount of 20 to 65% by weight.
To prepare a sintered body raw material. Specifically, a simple substance and / or compound of a rare earth element containing Sc and Y and a simple substance and / or compound of an alkaline earth element are added as a sintering aid, and further a simple substance and / or a compound of boron are added.
Alternatively, a compound, a simple substance of silicon and / or a compound is added. Further, an oxide of Al or the like is added as needed.
These are added to the AlN powder in a total range of 20 to 65% by weight. Note that oxygen is added as an oxide of a Group 3A element or a Group 2A element, an oxide of Al, or impurity oxygen contained in AlN powder.

Examples of Group 3A elements (rare earth elements including Sc and Y) in the periodic table include Sc, Y, La, Ce and P.
r, Nd, Sm, Eu, Gd, Τb, Dy, Ηo, E
Any of r, Δm, Yb, and Lu can be used. As a Group 2A element (alkaline earth element) in the periodic table, any of Ca, Mg, Sr, Ba, and Be can be used. Particularly industrially, Y and Ca are preferably used. It is particularly preferable to add these elements as oxides, and compounds that become oxides under sintering conditions may be used. That is, carbonates, nitrates, oxalates, sulfates, hydroxides and the like can be used. In addition, 3
The group A element and the group 2A element may be added in the form of a halide, an acid halide, an acetylide compound, a carbide, a hydride, a nitride, a silicide, a sulfide, or the like. Boron may be added alone, or may be added as a borate compound such as Al borate, rare earth borate, or alkaline earth borate, an oxide, or a compound with a transition metal such as Ti or W. Silicon may be added alone, nitride,
It may be added as an oxide, a compound with a transition metal such as Ti or W, or the like.

The amount of the rare earth element compound and the alkaline earth element compound described above, the amount of oxygen and the amount of Al oxide contained in the raw material powder, and the amount of boron alone or a compound or silicon alone or the compound Is the total amount
In order to satisfy 20 to 65% by weight and to realize densification by low-temperature sintering with higher reproducibility, (rare earth elements):
(Alkaline earth element): (oxygen): (boron): (silicon)
= (16-31): (4-10): (9-17): (0.4-1.6): (0.3
~ 1.2) is preferably satisfied. The central value of this composition is (rare earth element) :( alkaline earth element) :( oxygen) :( boron) :( silicon) = 23.6: 7.
1: 11: 0.8: 0.62. Low values of sintering can be easily achieved if the values before and after this, that is, within the above range. More preferably, (rare earth element): (alkaline earth element): (oxygen): (boron): (silicon) = (18-29):
(5-9): (9-15): (0.5-1.4): (0.4-1.0), and more preferably (rare earth element): (alkaline earth element): (oxygen): (boron): (Silicon) = (20-27) :( 6
88): (10:13): (0.5 to 1.2): (0.4 to 0.9).

The (oxygen) amount indicates the sum of the amount of oxygen contained in the AlN powder and the amount of oxygen in the added Al oxide (Al ₂ O ₃ ), and is a rare earth oxide or alkaline earth oxide. The amount of oxygen when a substance or the like is used is not included in the above composition ratio. Similarly, the composition ratio does not include oxygen when WO ₃ or the like is used as a coloring agent or oxygen when Β ₂ O ₃ is used as a boron source. In the case where rare earth borates or alkaline earth borates are used as the boron source, the amounts of the rare earth elements and alkaline earth elements contained in these borate compounds are not included in the above composition ratio. However, the total amount must satisfy the range of 20 to 65% by weight. The above-mentioned rare earth element, alkaline earth metal element, boron, silicon and oxygen simple substance or compound are more preferably added in the range of 40 to 65% by weight, and still more preferably in the range of 50 to 65% by weight.

The AlN sintered body raw material powder prepared as described above is sufficiently mixed using a ball mill or the like. A colorant for the sintered body may be added to the sintered body raw material powder as needed. As the coloring agent, Δi, Zr, Hf, W,
A simple substance of a transition metal belonging to Group 4A or 6A of the periodic table such as Mo;
Examples thereof include oxides, carbides, fluorides, carbonates, oxalates, nitrates, and nitrides (Mn alone or a compound is not used).

For sintering, a normal pressure sintering method, a hot press method, or the like can be applied. In the case of the normal pressure sintering method, a binder is added to the raw material powder of the sintered body, kneaded, granulated, and sized, and then formed into a desired shape. As a molding method, a die press, an isostatic press, a sheet molding and the like can be applied. Next, the compact is heated in, for example, an N ₂ gas stream or an air stream to remove the binder, and then sintered under normal pressure. The sintering temperature depends on the type of additive used.
It is preferable to set in the range of 3K. Sintering temperature 1673K
If it is less than 1, it is difficult to densify even if the additive composition according to the present invention is used, while if it exceeds 1873 K, it becomes difficult to realize a reduction in production cost due to low-temperature sintering.

According to the additive composition (subcomponent composition) of the present invention described above, sintering can be performed at a lower temperature than when a compound of a group 2A element or a group 3A element is added alone. Preferred composition ratio of the added additive, that is, (rare earth element) :( alkaline earth element) :( oxygen) :( boron) :( silicon) = (16-31) :( 4-10) :( 9-17) :
(0.4 to 1.6): By satisfying (0.3 to 1.2), densification and sintering can be performed at a lower temperature than when the composition is out of this composition range. The sintering temperature is preferably in the range of 1733 to 1863K, more preferably 1753 to 1853K. The sintering time is preferably in the range of 0.5 to 100 hours.
The time is more preferably 1 to 60 hours, and further preferably 4 to 30 hours.

On the other hand, in the case of the hot press sintering method,
The raw material powder of the sintered body mixed by the above-mentioned ball mill or the like may be press-molded or directly hot-pressed. The sintering temperature conditions and the like at this time are the same as in the normal pressure sintering described above.

[0032]

Next, specific examples of the present invention will be described.

Example 1 The amount of impurity oxygen was 1.00% by weight, and the average primary particle diameter was 0.6 μm.
5 μ% by weight of AlN powder
The Y ₂ O ₃ having a purity of 99.9 wt% 19.69 wt%, CaC
O ₃ 11.65% by weight, Al ₂ O ₃ having an average particle size of 0.8 μm
14.27% by weight, 1.65% by weight of La @ ₆ having an average particle size of 1 μm
, 0.66% by weight of Si ₃ N ₄ having an average particle size of 0.5 μm, and 0.3% by weight of WO ₃ as a colorant were added thereto.
After adding butanol, the mixture was pulverized and mixed by a wet ball mill, and then n-butanol was removed to obtain a sintered material powder.

Subsequently, after adding 5% by weight of an acrylic binder to the above-mentioned raw material powder of the sintered body and granulating, the granulated powder was
Molding was performed under uniaxial pressure of 50 MPa to produce a molded article having a concave shape. The molded body was heated to 773 K in an air atmosphere to remove the acrylic binder. Next, the binder removal body was set in a sintering vessel made of an AlN sintered body, and was heated under a nitrogen gas atmosphere of 1 atm in a graphite heater furnace.
The resultant was fired at 1823K for 6 hours to obtain an AlN sintered body.

The obtained AlN sintered body was black, had no color unevenness or uneven firing, and had a clean surface. When the density was measured by the Archimedes method, it was sufficiently dense to 3.30 g / cm ³ . In addition, a 10mm diameter and 3mm thick disk was cut out from the AlN sintered body and JIS-R161 was used at room temperature of 294 ± 2K.
When the thermal conductivity was measured by the laser flash method according to 1, it showed a good value of 70 W / m K.

Further, glass sealing was performed in a nitrogen atmosphere in a state where two of the obtained concave AlN sintered bodies were stacked. The glass composition used for sealing is as shown in Table 1 below.

[0037]

[Table 1] After filling the sealed AlN sintered body with helium gas at 5 atm and leaving it in the chamber for 40 minutes,
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 such treatment, a helium leak test (fine leak detection) was performed. The amount of helium leak was detected by a mass spectrometer. As a result, a favorable value of less than 1.0 × 10 ⁻¹⁰ atm · cc · s ⁻¹ was shown. Further, a gross leak test was performed. Specifically, the sample was placed in Sumitomo 3M Fluorinert No. 40 heated to 393K and left for 3 minutes, but no bubbles were generated and no gross leak was observed. Thus, it was confirmed that the AlN sintered body of the present invention was excellent in glass sealing property. In addition, favorable results were also obtained for copper metallization.

Examples 2 to 38, Comparative Examples 1 to 9 Except that the sintering conditions (temperature and time) shown in Tables 6 and 7 were applied using AlN powders and additives shown in Tables 2 to 4. An AlN sintered body was manufactured in the same manner as in Example 1. Table 5 shows the composition ratio of the additives (rare earth element: alkaline earth element: oxygen: boron: silicon) and the like. The characteristics of each of the obtained AlN sintered bodies were measured in the same manner as in Example 1. The results are shown in Tables 6 and 7. The good surface condition in Tables 6 and 7 means that there is no color unevenness or uneven printing, and that a large amount of precipitate is not visually observed on the surface.

[0039]

[Table 2]

[Table 3]

[Table 4]

[Table 5]

[Table 6]

[Table 7]

[Table 8]

[0040]

As described above, the aluminum nitride sintered body of the present invention can be densified by low-temperature sintering at around 1673 to 1873 K, and has a thermal conductivity of 40 W / m K or more and a high resistance. It has folding strength and can perform glass sealing and copper metallization satisfactorily. Therefore, it is possible to provide an aluminum nitride sintered body suitable as a circuit board, a package base, or the like.

[0041]

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Fumio Ueno 1st, Komukai Toshiba-cho, Saiwai-ku, Kawasaki-shi, Kanagawa Prefecture Toshiba R & D Center (56) References JP-A-62-176961 (JP, A) ( 58) Field surveyed (Int.Cl. ⁶ , DB name) C04B 35/581

Claims (2)

(57) [Claims] An AlN, a B element, a Si element, an O element,
What is claimed is: 1. An aluminum nitride sintered body comprising: an Al element; a composition comprising a Group 3A element and a Group 2A element of the periodic table, wherein said composition is contained in the range of 20 to 65% by weight, and The composition ratio of B element, O element, Si element, 3A element and 2A element of (3A element): (2
Group A element): (oxygen): (boron): (silicon) = (16-3)
1): (4 to 10): (9 to 17): (0.4 to 1.6): (0.3 to 1.2) and a thermal conductivity of 40 to 80 W / mK Union. 2. An AlN powder containing at least a Β element and Si
The element, the O element, the simple substance or the compound of the group 3A element and the group 2A element of the periodic table, and the composition ratio of the element based on the main starting material of each element are (group 3A element) :( group 2A element) :( oxygen ) :( boron) :( silicon) = (16-31) :( 4
To 10): (9 to 17): (0.4 to 1.6): a step of adding a total of 20 to 65% by weight while satisfying (0.3 to 1.2) to prepare a sintered body raw material; Baking the raw material of the sintered body at a temperature of 1673 to 1873K.