JPH03155693A - Manufacture of aluminum nitride wiring board - Google Patents

Abstract

PURPOSE:To obtain a nitriding aluminum interconnection substrate which has a high density and excellent heat conductivity without increasing the resistance of conductor made of tungsten by installing a laminated body of AlN green sheet wherein a conductor pattern is printed with W paste to an enclosed vessel made of nitriding ceramics and firing the laminated body under a nitrogen gas ambient atmosphere at or below a temperature at which said nitriding ceramics starts decomposition. CONSTITUTION:A green sheet, after dried, is punched into 100mm square. This punched green sheet is screen-printed with W paste and then grease-removed for 4 hours under an N2 ambient atmosphere of 900 deg.C after the lamination. Then, this green sheet 3 is set into a nitriding ceramics enclosed vessel 1 and fired at a temperature ranging from 1550 to 1750 deg.C under an N ambient atmosphere or more specifically at or below the temperature at which nitrides start decomposition. W is not affected by the vessel according to this manufacturing method. Therefore, conductor resistance indicates a proper value and provides an accurate substrate having an excellent thermal conductivity.

Description

[Detailed Description of the Invention] [Summary] Regarding a method for manufacturing an aluminum nitride wiring board, a conductor pattern was printed using tungsten paste with the aim of putting into practical use a method for manufacturing an aluminum nitride wiring board with a low conductor resistance value. After laminating the aluminum nitride green sheets, the laminated body is placed in a sealed container made of nitride ceramics such as aluminum nitride or silicon nitride, and the temperature is lower than the temperature at which the oxide ceramic starts to decompose in a nitrogen gas atmosphere. The method for manufacturing an aluminum nitride wiring board is characterized in that the laminated body is integrated by firing and sintering the aluminum nitride wiring board.

[Industrial application field]

The present invention relates to a method of manufacturing an aluminum nitride wiring board.

Due to the need to process a large amount of information at high speed, information processing devices are becoming smaller and larger in capacity, and the degree of integration of semiconductor integrated circuits that form the main body of these devices has improved, and LSI and VLSI have been put into practical use.

These integrated circuits are mounted as chips on a chip mounting substrate (interposer) made of ceramics to create a LS [modinir], which is then mounted as a replacement unit on a printed wiring board, etc. There is a toretsu.

As described above, as the degree of integration of semiconductor integrated circuits increases and high-density packaging is performed, the amount of heat generated by devices is also increasing at an accelerating pace.

That is, initially, the amount of heat generated per IC chip was approximately 3.
The amount of heat generated per LSI chip used to be as low as 5W, but now the amount of heat generated per LSI chip has increased to about 10W.If a large number of chips are installed in a matrix, the amount of heat generated is enormous, and this is likely to increase further. It is in.

Conventionally, alumina (A12es), which has high thermal conductivity and excellent heat resistance, has been used for substrates on which LSI chips and the like are mounted.

However, alumina has an excellent thermal conductivity of 20W.
/sK, which is insufficient as a material for the above-mentioned chip mounting substrate.

Therefore, attention has been focused on AIN, which has a high thermal conductivity of 320 W/mK (theoretical value), and efforts are being made to put this substrate into practical use.

Table 1 compares the characteristics of both.

Table 1 shows that in addition to excellent thermal conductivity, AIN has a small coefficient of thermal expansion, and the coefficient of thermal expansion (3
, 6X 10-'/t), and the dielectric constant is small, which is advantageous in terms of reducing signal delay time and reducing crosstalk when forming a multilayer substrate.

[Conventional technology]

Since An has a high melting point and the substrate is fired at a high temperature exceeding 1800°C, tungsten (W) with a high melting point is used as the constituent metal of the conductor line, and the electronic circuit is formed by screening W paste on a green sheet. This is done by printing and firing.

Furthermore, the materials for constructing the firing container for storing and firing Glyci-1 are limited, and materials such as boron nitride (BN) and graphite (C), which are stable even at high temperatures, are used.

However, as a result of studies using these firing containers, it was found that substrates fired using graphite containers showed a significant weight loss due to the reducing power of graphite, and a dense substrate could not be obtained.

In addition, when using an ON container, it is effective for densifying Al, but BN reacts with W, resulting in tungsten boride (11,
8) and significantly increased the conductor resistance.

From the above, we found that BN containers are suitable for firing AIN green sheets.
It is not suitable for firing N-green sheets, and a solution to this problem was needed.

[Problem to be solved by the invention]

8N used in firing IN Grin sheet
The firing container is used to obtain an AIN substrate with high thermal conductivity, and is not suitable for firing ^j2N green sheets provided with conductor lines such as W.

Therefore, the challenge is to put into practical use a firing container suitable for this purpose.

[Means to solve the problem]

The above problem was solved by laminating βN green sheets printed with conductive patterns using W paste, then placing this laminated body in a closed container made of nitride ceramics such as aluminum nitride or silicon nitride, and placing it in a nitrogen gas atmosphere. The patent N-I is characterized in that the nitride ceramic is fired and sintered at a temperature below the temperature at which it begins to decompose, thereby integrating the laminate. This problem can be solved by configuring the substrate manufacturing method.

Table 2 [Function] Conventionally, the firing temperature of AiN green sheets was 1800 to 19
It is said that 00℃ is preferable, and from this point of view, the melting point is 3
Graphite with a temperature of 550℃ and EI with a melting point of 3000℃ or higher
N and the like have been used as firing containers.

However, the inventors found that by extending the firing time compared to the conventional method, the firing temperature could be lowered to 1550° C. or higher, and a sufficiently dense substrate could be obtained.

Therefore, aluminum nitride (^lN) is used as a firing container.
Alternatively, nitride ceramics such as silicon nitride (Si3N4) can be used; in this case, it has been found that the conductor resistance shows its original value because W is not affected by the firing vessel.

Table 2 shows the relationship between the melting point and boiling point of these nitrides.

On the other hand, when using these nitrides as containers, it is important to note that their melting point is lower than that of 6N or graphite, so if the firing temperature is too high, the vapor pressure will be high and the consumption will be rapid. As a result of experiments, the inventors determined that the firing temperature should be set at 1750°C.
I found that I could do the following.

Furthermore, as for sintering aids used in sintering ceramics, yttrium (Y)-based compounds (e.g., yttrium oxide Yarn) and calcium (Ca)-based compounds (e.g., calcium carbonate CaC05) have been used. Y-based materials have a liquid phase generation temperature as high as 1700° C. or higher, and are therefore unsuitable for firing at lower temperatures than conventional ones, as in the present invention.

On the other hand, Ca-based systems are suitable for the purpose of the present invention because their liquid phase generation temperature is 1400°C or higher, which is lower than that of Y-based systems. is suitable for use.

Next, the appropriate amount of the sintering aid added is 0.5 to 10% by weight based on 100 parts by weight of AlN.

Further, as the conductor material, W paste may be used as in the case of conventional alumina substrates.

〔Example〕

Add CaC as a sintering aid to 100 parts by weight of A11N powder. Alternatively, a mixture of CaCO5 and Y2O is used, with 10 parts by weight of polyvinyl butyral (abbreviated as PVB) as a binder and dibutyl phthalate (abbreviated as D) as a plasticizer.
Add 10 parts by weight of IP) and 50 parts by weight of ethyl alcohol as a dispersion medium, knead with a ball mill to make a slurry, and use the doctor blade method to form a slurry with a forming gap of 450 μm.
A green sheet was produced by molding at a feed rate of 2.3 m/min.

After drying this green sheet, it was punched out into a 100 M square, W paste was screen printed on this green sheet, the sheets were laminated, and then degreased for 4 hours in a N2 atmosphere at 900 tons.

Next, this green sheet was set in the nitride ceramic sealed container shown in Figure 1, and fired under various conditions shown in Tables 3 and 4, and the density, thermal conductivity, and conductor resistance of the substrate were measured. .

The structure of the nitride ceramic closed container shown in Fig. 1 is exactly the same as the conventionally used B~ and graphite closed containers, and in the case of this example, the size of the closed container 1 made of nitride ceramics is The inner diameter is 1100mm x 1
00 square, and inside this is a setter made of the same nitride ceramics with a thickness of 5 bars, on which the previously formed green sheet 3 is set, and on top of this is a lid 4 made of nitride ceramics. is covered.

Then, this nitride ceramic hermetic container was Table 8 Fourth table These were replaced with those made by iN and 5isN4, respectively.

The temperature was raised to a set temperature in an atmosphere at a heating rate of 600° C./hour, heated for a set time to perform sintering, and then naturally cooled and taken out.

Table 3 shows the results of firing using a sealed container made of IN, and Table 4 shows the results of firing using a sealed container made of Si, N. The columns are marked with O marks, Δ, ×, ◎, etc., and the Q marks in the sintered density column are 99.0% or more, and the Δ marks are 97.0 to 99.
0. The X mark indicates a density of 97.0% or less.

Also, the O mark in the thermal conductivity column is 180W/mK or higher.

Δ mark is 150 to 180 W/mK, X mark is 150 W/mK
This indicates that the value is less than mK.

Further, in the conductor resistance column, the O mark indicates a value of 15 iΩ or less, the Δ mark indicates a value of 15 to 20 mΩ/mouth, and the X mark indicates a value of 20 ffiΩ/mouth or more.

Further, the mark ◎ indicates that the processing conditions are recommended by the inventors.

In Tables 3 and 4, good results were obtained in Examples 1 to 14, but other conditions had some problems and were not preferred.

That is, in Example 15, although the substrate itself was good, the firing temperature was high and the time was long, resulting in considerable wear and tear on the closed container.

Further, in Example 16, the sintering of the substrate did not progress because the firing time was too short.

Furthermore, in Examples 17 and 18, sintering did not progress because the firing temperature was too low.

Further, in Examples 19 and 20, the firing of the Aj2N substrate was good, but the conductor resistance was abnormally increased, so it was defective.

Further, in Example 21, sintering did not proceed because iN and the sintering aid were reduced by graphite.

As can be seen from the above results, Af
A substrate with good characteristics can be obtained by placing an N-green sheet in a closed container made of nitride ceramics and firing it at a temperature below the temperature at which the nitride begins to decompose, such as 1550 to 1750°C.

〔Effect of the invention〕

As described above, by carrying out the present invention, Aj? N
you can get the board

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a nitride ceramic sealed container according to the present invention. In the turn, l is a closed container, 3 is a green sheet, 2 is a setter 4 is a lid, and these are.

Claims (2)

[Claims] (1) After laminating aluminum nitride green sheets with conductor patterns printed using tungsten paste,
The laminate is placed in a closed container made of nitride ceramics, and fired and sintered in a nitrogen gas atmosphere at a temperature below the temperature at which the nitride ceramic begins to decompose, thereby integrating the laminate. A method for producing a featured aluminum nitride wiring board. (2) A method for manufacturing an aluminum nitride wiring board, characterized in that the sealed container made of the nitride ceramic according to claim 1 is made of aluminum nitride or silicon nitride.