JP2605045B2 - Aluminum nitride sintered body - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an aluminum nitride sintered body used for an insulating substrate, a heat sink, a semiconductor package material, and the like.
More particularly, the present invention relates to a black aluminum nitride sintered body which can be produced at a low temperature and has high density and high thermal conductivity.

[Prior Art] In recent years, with high integration and high density of LSI, an insulating substrate material having good thermal conductivity has been demanded. Conventionally, an alumina sintered body is most often used as an insulating substrate material.
However, the thermal conductivity of the alumina substrate is low (about 20 w / m.
k) Since the coefficient of thermal expansion is larger than that of silicon, there are many problems such as poor jointability. Therefore, the thermal conductivity is good,
An aluminum nitride (AIN) sintered body having a coefficient of thermal expansion close to that of silicon has attracted attention. Further, the aluminum nitride sintered body has a high mechanical strength (40 to 50 kg / mm ² ), a small dielectric constant, and excellent electric characteristics. However, it is difficult to obtain a dense sintered body because aluminum nitride has a strong covalent bond and is a difficult-to-sinter material. For this reason, various attempts have been made to obtain a dense aluminum nitride sintered body by a hot press method using a sintering aid or a normal pressure sintering method, but the hot press method is not preferable because of low productivity. In the normal pressure sintering method, a rare earth compound or an alkaline earth compound is used as a sintering aid to obtain a dense sintered body having a high thermal conductivity. Is required in view of productivity.

As a low-temperature sinterable AIN sintered body in consideration of productivity, a production method by simultaneous addition of a rare earth oxide and an alkaline earth oxide is disclosed in JP-A-61-117160. Also, JP-A-61-2
70262 and JP-A-61-270263 describe a high thermal conductive aluminum nitride sintered body comprising a boride or carbide of a group 4a, 5a or 6a element of the periodic table and aluminum nitride, and a method for producing the same. However, further improvement has been desired in obtaining higher thermal conductivity.

The inventors of the present invention filed earlier, found a low-temperature sintered body by adding calcium tungstate in JP-A-61-270390, the thermal conductivity of the obtained sintered body is JP-A-61-117160,
JP-A-61-270262, about 100w / mk similar to JP-A-61-270263
Was staying at

As a recent example, Japanese Patent Application Laid-Open No. 62-72570 discloses that TiO ₂ or ZrO ₂
Although Sc ₂ O ₃ addition is indicated, the use of expensive Sc ₂ O ₃ is not preferable, and the thermal conductivity of the obtained sintered body is still about 100 watts.
/ mk.

[Problems to be Solved by the Invention] An object of the present invention is to provide a black aluminum nitride sintered body having high density and high thermal conductivity and capable of being sintered at a relatively low temperature.

[Means for Solving the Problems] The inventors of the present invention discovered that low-temperature sintering of aluminum nitride by adding calcium tungstate (CaWO ₄ ) was started, and simultaneous addition of Y ₂ O ₃ and further addition of CaWO ₄ Off CaO and WO
It has been found that the aluminum nitride sintered body obtained by setting the composition ratio to ₃ has high thermal conductivity without impairing the low-temperature sinterability.

Aluminum nitride Ca or Ca compound, Y or Y compound and W or W compound CaO, Y ₂ O ₃ , the total converted value of WO ₃ 0.15 ~
15 wt%, WO ₃ corresponding value 0.1 wt% or more, Y ₂ O ₃ in terms of value, 0.5
8 containing by weight% less than the sintering aid, the CaO, Y ₂ O _3, W
When the total amount of O ₃ conversion is 100% by weight, the WO ₃ value is
10 to 90% Y ₂ O ₃ value of 5% to 90%, the ratio of CaO value and WO ₃ value 9: 1
ア ル ミ ニ ウ ム 1 to 9 to form a composition, and by sintering it contains metal W, is black and has high thermal conductivity. Aluminum nitride sintered body. The above aluminum nitride has an oxygen content of 3% or less. It is preferable to use aluminum nitride powder of the above. Examples of the Ca compound include CaO and a compound that becomes CaO upon firing. Examples of the Y compound include Y ₂ O ₃ or a compound which becomes Y ₂ O ₃ by firing. The W compounds include compounds comprising a WO ₃ by, for example, WO ₃ or firing. Although it is not known whether the compound becomes a single compound by firing, it is a matter of course that a composite oxide such as CaWO ₄ can be used. The aluminum nitride powder and the sintering aid powder have a fine average particle diameter of 10 μm or less, and particularly preferably 5 μm or less.

In the present invention, for convenience, the term "sintering aid powder" is used, but a liquid sintering aid is also included.

If the total amount of Ca or Ca compound, Y or Y compound and W or W compound is less than 0.15% by weight in terms of CaO, Y ₂ O ₃ and WO ₃ , the addition effect cannot be sufficiently achieved, and if it exceeds 15% by weight. Lower the sintered body.

In the present invention, Ca or compound, Y or Y compound, W or W compound of the sintering aid are all weight% calculated as CaO, Y ₂ O ₃ and WO ₃ and the balance is aluminum nitride compound and the total weight is 100. %, And as a result, each sintering aid obtained by calculation,
The weight percentage of aluminum nitride is called a converted value.

The addition amount is desirably the minimum necessary in consideration of the capacity of the manufacturing equipment to be used and the desired characteristics of the sintered body. The composition ratio of the sintering aid is determined by the desired sintering characteristics, for example, by setting a black aluminum nitride sintered body, or having a high thermal conductivity or a sintering temperature.

As a composition for obtaining a black aluminum nitride sintered body required for a semiconductor package, CaO, Y
₂ O _3, when the amount sum of the converted values of WO ₃ and 100% by weight, in the present invention the terms _of WO ₃ values, and WO ₃ values (hereinafter also,
CaO and CaO value, a Y ₂ O _3, that Y ₂ O ₃ value) the value is 10% to 90%
In, preferably may range from 20 to 80%, and WO ₃ in terms of value 0.1 wt% or more, preferably to contain more than 0.3 wt%. If it is out of this range, it will not show black,
Insufficient sintering.

Next, as a composition for obtaining high thermal conductive aluminum nitride, the Y ₂ O ₃ value is preferably in the range of 5 to 90%, preferably 20 to 80%, and the balance of CaO and WO ₃ in the ratio of each converted value of WO ₃ is good. : WO ₃ = 9: 1 ~
1: 9, preferably in the range of 4: 1 to 1: 4. Further, the equivalent value of Y ₂ O ₃ is 0.5 to less than 8% by weight, preferably 1 to 5% by weight or less. Outside this range, the desired high thermal conductivity cannot be achieved or sintering becomes insufficient. In order to obtain a black aluminum nitride sintered body having high thermal conductivity, a range overlapping the above range may be used.

The reason for the improvement in the thermal conductivity and the effect of the low-temperature sinterability of the aluminum nitride sintered body of the present invention is unknown at present, but from the results of X-ray diffraction of the sintered body, CaO-Al ₂ O _{3 is} considered. WO ₃ -Al ₂
It has been found that an O ₃ -based low melting composition exists. Since metal W, Y ₂ O ₃ —Al ₂ O ₃ compound, CaO—Al ₂ O ₃ compound, etc. were detected as the second components, CaO and WO ₃ components contributed to low-temperature sinterability, the Al ₂ O ₃ component generated newly by the dissociated oxygen component from WO ₃ in sintering process Y ₂ O ₃ component Y
High thermal conductivity is estimated to emerge by fixing the ₂ O ₃ -Al ₂ O ₃ compound. This is Y ₂ O ₃
This can be considered from the fact that the thermal conductivity changes depending on the amount of addition. Thermal conductivity also depends on the ratio of CaOWO ₃ ,
In this regard, it has only been found that the most effective composition corresponds to Ca ₃ WO ₆ .

The presence of the metal W of the present invention is considered to significantly contribute to the blackening of the aluminum nitride of the present invention and the improvement of the thermal conductivity.

Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited thereto.

[Example 1] [Example 1] CaCO ₃ powder of 1% by weight in terms of CaO, 3.5% by weight of Y ₂ O ₃ powder and 3.5% by weight of anhydrous WO ₃ powder were added to aluminum nitride powder having an average particle diameter of 2 μm containing 1.7% by weight of oxygen as an impurity. 0.5
% By weight was added and mixed. Next, 2% by weight of a molding binder was added and granulated, and then molded at room temperature under a pressure of about 1200 kg / cm ² to obtain a molded body having a diameter of about 25 mm and a thickness of about 5 mm. The compact was held in a nitrogen atmosphere at 600 ° C. for 5 hours to remove the binder, then placed in a boron nitride container, and sintered at 1700 ° C. for 3 hours under normal pressure in a nitrogen atmosphere to obtain an aluminum nitride sintered body. I got The characteristics of the obtained sintered body are shown in Table 1
No.1 is shown.

[Examples 2 to 14] Using CaWO ₄ powder, Y ₂ O ₃ powder, CaCO ₃ powder and WO ₃ powder as the aluminum nitride powder used in Example 1, conversion of the total by the composition ratio of the numbers in FIG. An aluminum nitride sintered body was obtained in the same manner as in Example 1 except that the amount of addition was 5% by weight. The properties of the obtained sintered body are shown in Tables 1 and 2 as composition Nos. 2 to 14.

Example 15 - 19] The weight ratio of the sintering aid of aluminum nitride powder used in Example _{1, Y 2 O 3: CaO:} WO 3 = 10: 4: 6 to become so mixed, respectively, performed An aluminum nitride sintered body was obtained in the same manner as in Example 1. Compositions Nos. 15 to 19 in Table 1 show the amounts of the respective sintering aids and the characteristics of the obtained sintered bodies.

[Examples 20, 21] To the aluminum nitride powder used in Example 1, Y ₂ O ₃ powder, CaO converted CaCO ₃ powder and WO ₃ powder in the amounts shown in Table 1 were added, and the same as in Example 1 After molding and debinding, the mixture was placed in an aluminum nitride container and sintered under normal pressure at 1700 ° C. for 15 hours in a nitrogen atmosphere to obtain a sintered body. The properties of the obtained sintered body are shown in Table 1, Composition Nos. 20 and 21.

[Comparative Examples 22 to 32] Aluminum nitride sintered bodies were obtained in the same manner as in Example 1 except that the total amount of the sintering aid added was 5% by weight in the compositions of Nos. 23 to 32 in the numbers in FIG. The properties of the obtained sintered body are shown in Table 1, Composition Nos. 22 to 32. Comparative Example 22 is an example in which Y ₂ O ₃ : CaO: WO ₃ = 10: 4: 6 was mixed as in Examples 15 to 19, and WO ₃ was 0.06%, which is outside the scope of the present invention. .

Table 2 shows the changes in the sintered body characteristics when the sintering temperature was changed in Examples 2, 4, and 13 and Comparative Examples 24 and 29.
The composition of the present invention is sufficiently densified even at a firing temperature of 1650 ° C., and has a high thermal conductivity.

2 and 3 are respectively on the lines 25-29 of FIG.
26-30 line of Y ₂ O ₃ ratio of 50%, showing a 30% and a ratio dependency of CaO / WO ₃ in the thermal conductivity in the case of a constant. CaO: WO ₃ = 9: 1 to 1: 9
It can be seen that the thermal conductivity is improved in the range of.

C. Effect of the Invention As described above, the aluminum nitride sintered body of the present invention has a high density and high thermal conductivity, exhibits a black color excellent in light-shielding properties, and has a sintering temperature of 1800 ° C or less, which is an alumina porcelain. At the normal temperature of the reduction firing facility. This will be
The aluminum nitride sintered body facilitates the development of not only an insulating substrate, a heat sink and the like but also a conductor on a co-fired substrate, and the industrial value of the invention is great.

[Brief description of the drawings]

FIG. 1 is a component diagram showing a sintering composition ratio of a part of the present invention and a comparative example. FIG. 2 is a characteristic diagram showing the relationship between the composition ratio of CaO and WO ₃ obtained from Examples 3, 4, and 5 and Comparative Examples 25 and 29, and the thermal conductivity of a sintered body thereof. FIG. 3 shows Examples 6, 7, 8, 9 and a comparative example.
FIG. 6 is a characteristic diagram showing the relationship between the composition ratio of CaO and WO ₃ obtained from 26 and _30, and the thermal conductivity of the sintered body thereof.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Tetsu Nishiyama Examiner, Narumi Technical Research Institute, Narumi-cho, Midori-ku, Nagoya City, Aichi Pref. JP-A-61-270263 (JP, A) JP-A-61-117160 (JP, A)

Claims (1)

(57) [Claims] An aluminum nitride containing Ca or Ca compound, Y or Y compound and W or W compound in total of 0.15 to 15% by weight in terms of CaO, Y ₂ O ₃ and WO ₃ and 0.1% by weight or more in terms of WO ₃ , Y ₂ O ₃
Converted value, containing 0.5 to less than 8% by weight of a sintering aid,
aO, Y ₂ O _3, when the amount sum of WO ₃ corresponding value as 100 wt%, WO ₃ value 10~90%, Y ₂ O ₃ value of 5 to 90%, CaO value and WO ₃
An aluminum nitride sintered body comprising a metal W by forming a composition having a value ratio of 9: 1 to 1: 9 and firing, and having black and high thermal conductivity.