JPH07235769A - Aluminum nitride wiring board and manufacturing method thereof - Google Patents

Abstract

(57) [Summary] [Purpose] Without mixing the substrate components with the wiring metal,
Provided is an aluminum nitride wiring board in which the wiring metal layer is uniformly densified to the inside and the bonding between the aluminum nitride base material and the wiring metal layer is stabilized, and a manufacturing method thereof. [Structure] In an aluminum nitride wiring substrate 4 provided on at least one of the surface and the inside of the aluminum nitride substrate 1 and having a wiring metal layer 3 co-fired with the aluminum nitride substrate 1, the wiring metal layer 3 mainly comprises it. In addition to wiring metal such as tungsten, manganese
It is contained in the range of 2% by weight or less. Such an aluminum nitride wiring board 4 is manufactured by adding a manganese component for densifying tungsten to at least one of the aluminum nitride green sheet and the wiring layer forming metal paste when manufacturing an aluminum nitride molded body. be able to.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum nitride wiring board formed by co-firing a wiring metal layer with, for example, an aluminum nitride base material, and a method for manufacturing the same.

[0002]

2. Description of the Related Art In recent years, the demand for ceramic substrates has been increasing year by year with the development of semiconductor devices such as power ICs and high frequency transistors which require large currents. In particular, since the aluminum nitride substrate has features such as high thermal conductivity and excellent heat dissipation, it is attracting attention as a substrate that can cope with the increasing amount of heat dissipation from semiconductor elements.
When the aluminum nitride substrate as described above is used as a semiconductor package, a circuit board, or the like, it is general to simultaneously manufacture the aluminum nitride substrate and the wiring metal layer by cofiring.

A method of manufacturing a general co-fired aluminum nitride substrate will be described. First, a wiring layer forming metal paste containing a wiring metal is applied in a desired wiring shape on a ceramic green sheet. One layer or a plurality of layers are laminated so as to have a desired shape to produce an aluminum nitride compact. Next, the aluminum nitride compact is subjected to degreasing treatment and the like, and then fired at a predetermined temperature to simultaneously sinter the aluminum nitride base material and the wiring metal.

As the wiring metal in the above-mentioned aluminum nitride co-fired substrate, for example, JP, A, 60-253294 is used.
Molybdenum, tungsten, as described in
Single metals such as platinum and manganese and alloys containing two or more of these metals are used. Among them, tank stainless is mainly used because it has a thermal expansion coefficient similar to that of aluminum nitride. In such an aluminum nitride co-fired substrate, the bonding between the wiring metal tungsten and the aluminum nitride sintered body is maintained by the anchor effect in which the composite oxide of the sintering aid and the aluminum oxide enters into each structure. It is considered to be dripping.

By the way, there is a difference between the sintering temperature of aluminum nitride and the densification temperature of tungsten in the firing process of the aluminum nitride co-fired substrate as described above.
Further, since the behavior of densification is different, there is a problem that pores are likely to remain in the wiring metal layer after the simultaneous firing. Further, there is a problem that the bonding itself between aluminum nitride and tungsten becomes unstable. Similar problems occur when other simple metals such as molybdenum are used. On the other hand, when molybdenum or an alloy of tungsten and manganese or the like is used, there is a problem that deterioration of the shape of the wiring metal layer, disconnection and the like are likely to occur due to the lowering of the melting point.

Therefore, conventionally, an aluminum nitride component or a sintering aid component thereof is added to a printing composition used for forming a wiring metal layer to reduce the sintering shrinkage ratio between the aluminum nitride sintered body and the wiring metal. It has been practiced to eliminate the pores with the aluminum nitride component as well as to match (for example, JP,
A, 1-300584). In this way, some efforts have been made to make the wiring metal layer dense.

[0007]

However, in the case where the aluminum nitride component or the sintering aid component is added to the wiring metal printing composition as described above, if the amount of these components increases, the wiring resistance of the wiring resistance increases. There was a problem that it was likely to cause an increase. In addition, when an aluminum nitride component containing a sintering aid component is mixed, a component that becomes a liquid phase during sintering is mixed in the wiring metal layer, and after the sintering, the component on the wiring metal layer or its periphery is mixed. Segregation of the liquid phase is likely to occur. For this reason,
There were problems such as abnormal plating and poor appearance.
Furthermore, if the wiring metal layer is not sufficiently densified, a swelling defect is likely to occur in the plating layer or the thin film wiring layer in the heating test after forming the plating layer or the thin film wiring layer on the wiring metal layer. There was a problem.

On the other hand, it has also been proposed to densify the wiring metal layer by filling the pores and gaps existing in the wiring metal layer of the aluminum nitride co-fired substrate with the metal deposited by the plating method ( See JP, A, 6-56563).
However, although this method is effective for the surface wiring layer and the like, it has a problem that the metal cannot be uniformly filled up to the internal wiring layer by the plating method.

The present invention has been made in order to solve such a problem, and makes it possible to uniformly densify the wiring metal layer to the inside without mixing the substrate components and the like with the wiring metal, and to make the aluminum nitride base material. The present invention aims to provide an aluminum nitride wiring substrate in which the bonding between the wiring metal layer and the wiring metal layer is stabilized, and further, the occurrence of poor conduction and poor appearance of the wiring metal layer, and the plating formed on the wiring metal layer. It is an object of the present invention to provide an aluminum nitride wiring board capable of preventing a swollen defect of a layer or a thin film wiring layer. Another object of the present invention is to provide a method for manufacturing an aluminum nitride wiring board which enables the aluminum nitride wiring board as described above to be manufactured with good reproducibility.

[0010]

An aluminum nitride wiring substrate of the present invention is an aluminum nitride substrate and a wiring metal layer provided on at least one of the surface and the inside of the aluminum nitride substrate and co-fired with the aluminum nitride substrate. In the aluminum nitride wiring board including the above, the wiring metal layer contains manganese in an amount of 2% by weight or less in addition to the metal mainly constituting the wiring metal layer.

Another aluminum nitride wiring substrate of the present invention is provided on the aluminum nitride substrate and on at least one of the surface and the inside of the aluminum nitride substrate,
And a wiring metal layer having a porosity of 2% or less.

The method for manufacturing an aluminum nitride wiring board according to the present invention comprises applying a wiring layer-forming metal paste containing a wiring metal in a desired shape onto an aluminum nitride green sheet, and laminating one or more layers of the paste. A method of manufacturing an aluminum nitride wiring board, comprising: a step of producing an aluminum molded body; and a step of firing the aluminum nitride molded body to simultaneously sinter the aluminum nitride base material and the wiring metal. At least one manganese component selected from manganese and manganese compounds is added to at least one of the green sheet and the wiring layer forming metal paste.

[0013]

In the present invention, manganese or a manganese compound that reacts with the metal mainly forming the wiring metal layer to densify the wiring metal layer is added to the aluminum nitride green sheet or the wiring layer forming metal paste. .
The added manganese or manganese compound promotes grain growth of the wiring metal and promotes densification, so that the densification of the wiring metal layer is almost completed in the co-firing process with the aluminum nitride base material. Therefore, for example, a wiring metal layer having a porosity of 2% or less can be obtained without adding an aluminum nitride component or a sintering aid component. In other words, a sufficiently densified wiring metal layer can be obtained by using a metal material that does not substantially contain an inorganic insulator as a constituent component of the wiring metal layer. Further, since the wiring metal is sintered quickly, the wiring metal that has been densified during the sintering of aluminum nitride is included in the aluminum nitride. Therefore, the bondability between the aluminum nitride base material and the wiring metal layer is also improved. When the wiring metal layer is densified to have a porosity of 2% or less, for example, it is possible to prevent a liquid component or an organic impurity component from entering the wiring metal layer during a plating step or a thin film forming step after firing. As a result, it is possible to avoid defective factors such as generation of decomposed gas components and abnormal swelling due to heat treatment accompanying product inspection, and thus it is possible to provide a highly reliable aluminum nitride wiring board.

[0014]

EXAMPLES Next, the present invention will be described in more detail by way of examples.

FIG. 1 is a cross-sectional view showing the structure of an embodiment in which the present invention is applied to an aluminum nitride multilayer wiring board by simultaneous firing. In the figure, 1 is an aluminum nitride multilayer substrate. This aluminum nitride multilayer substrate 1 is configured by integrating a plurality of aluminum nitride layers 2 into a multilayer. An internal wiring metal layer 3 having a predetermined wiring pattern is provided on the aluminum nitride layer 2, and the internal wiring metal layer 3 includes a wiring metal layer 3a filled in the through hole.

The aluminum nitride multilayer wiring board 1 and the internal wiring metal layer 3 constitute an aluminum nitride multilayer wiring board 4. The aluminum nitride multilayer substrate 4 is
For example, the aluminum nitride base material (aluminum nitride multilayer substrate 1) and the wiring layer forming metal material (the coating layer of the wiring layer forming metal paste) to be the internal wiring metal layer 3 are simultaneously fired.

The aluminum nitride multilayer substrate 1 is made of a general aluminum nitride sintered body. For example, a rare earth oxide powder such as yttrium oxide or aluminum oxide powder is added to aluminum nitride powder as a sintering aid. Then, the thing which sintered such a mixed powder is illustrated. Further, it is also possible to apply low temperature firing aluminum nitride using a fluoride such as yttrium fluoride or calcium fluoride as a sintering aid.

The internal wiring metal layer 3 is preferably made of a metal material that does not substantially contain an inorganic insulator such as an aluminum nitride component or a sintering aid component. Examples of the metal mainly forming the internal wiring metal layer 3 include refractory metals such as tungsten and molybdenum. These refractory metals may be used alone or as a mixture with an active metal such as titanium or zirconia or an active metal compound such as titanium nitride. In particular, in the present invention, it is preferable to use tungsten whose main coefficient of thermal expansion is similar to that of aluminum nitride as the main component. As the tungsten powder used for producing the wiring layer forming metal paste, it is preferable to use a relatively large powder having an average particle diameter of about 5 to 20 μm. Thereby, shrinkage of the wiring metal can be suppressed.

The above-mentioned internal wiring metal layer 3 contains a trace amount of manganese in addition to the metal mainly constituting the internal wiring metal layer 3, such as tungsten. Internal wiring metal layer 3
Manganese contained in the aluminum nitride multilayer substrate 1
This is due to the manganese component previously added to the aluminum nitride green sheet used for forming the above or the metal paste for forming the wiring layer. Examples of the manganese component include elemental metals of manganese and manganese compounds such as manganese oxide.

For example, manganese oxide and tungsten react during the simultaneous firing step to form a complex compound such as a complex oxide containing manganese and tungsten, or a complex such as a eutectic alloy of manganese and tungsten. To do. This composite (reactant) becomes a liquid phase during the simultaneous firing process. By interposing such a liquid phase, tungsten atoms, which have been difficult to sinter and are difficult to diffuse, are easily diffused. Thereby, the grain growth of the tungsten particles is promoted, and the tungsten wiring layer (internal wiring metal layer 3) can be sufficiently densified. According to such a densification process, the internal wiring metal layer 3 having a porosity of 2% or less can be obtained.

The densification effect as described above is achieved by the internal wiring metal layer 3 containing a composite containing a trace amount of wiring metal and manganese. Internal wiring metal layer 3 is 2
If the manganese content exceeds 5% by weight, the wiring metal (for example, tungsten) is dissolved, the formation of the internal wiring metal layer 3 cannot be maintained, and the aluminum nitride substrate 1
May deteriorate the characteristics of Therefore, the manganese content in the internal wiring metal layer 3 is preferably 2% by weight or less. On the other hand, if the manganese content in the internal wiring metal layer 3 is too low, the wiring metal cannot be sufficiently densified, so that the manganese content in the internal wiring metal layer 3 is 0.01.
It is preferable that the content is not less than weight%. A more preferable manganese content is in the range of 0.01 to 0.1% by weight.

The range of manganese content in the internal wiring metal layer 3 described above is when a general aluminum nitride substrate is used. That is, the aluminum nitride substrate 2023 ~
This is a case where it is manufactured by firing in a temperature range of about 2123K.
When a special aluminum nitride substrate is used, it is preferable to set the manganese content according to the firing temperature, firing time and the like. For example, in the case of low temperature firing aluminum nitride that can be fired at a temperature of 1873K or lower,
Manganese content in the internal wiring metal layer 3 is 0.1 to 2% by weight.
It is preferable to set it as the range.

As described above, even if the manganese component is added to either the aluminum nitride green sheet or the wiring layer forming metal paste, the internal wiring metal layer 3 can be similarly densified, but especially on the green sheet side. Is more preferably added to When the manganese component is added to the green sheet side, bonding with the internal wiring metal layer (for example, tungsten layer) 3 occurs from the aluminum nitride base material side, so that the bonding between the aluminum nitride substrate 1 and the internal wiring metal layer 3 is further strengthened. be able to. Further, since the compounding of the manganese component is easy to make uniform, it is possible to improve the uniformity of the density of the internal wiring metal layer 3.

In the aluminum nitride multilayer wiring board 4 of this embodiment, since the grain growth of the wiring metal is promoted and the sintering rate of the wiring metal is accelerated as described above, the porosity is 2% or less. Thus, the fully densified internal wiring metal layer 3, for example, a tungsten layer is obtained. Further, since the wiring metal having a higher densification is included when the sintering of the aluminum nitride occurs due to the faster sintering rate of the wiring metal, the aluminum nitride multilayer substrate 1 and the internal wiring metal layer 3 are The bonding property of can be stabilized.

The fully densified internal wiring metal layer 3 is
When forming a plating layer or thin film on it, liquid components and organic impurities do not enter the wiring layer, so avoiding defective factors such as generation of decomposed gas components and abnormal swelling due to heat treatment accompanying the inspection process. You can Further, since the internal wiring metal layer 3 does not contain unnecessary substances that cause poor continuity or poor appearance, for example, an aluminum nitride component or a sintering aid component, it has low resistance and excellent appearance.

The aluminum nitride wiring board of the above-mentioned embodiment is manufactured, for example, as follows.

First, an aluminum nitride green sheet containing a manganese component which reacts with the above-mentioned wiring metal to densify it, or an ordinary aluminum nitride green sheet is prepared. Through holes are formed at predetermined positions in these aluminum nitride green sheets.
Examples of the manganese component added to the aluminum nitride green sheet include a single metal of manganese and a manganese compound such as manganese oxide.

Here, when the manganese component is added to the aluminum nitride green sheet, it is preferably about 0.05 to 5 mol% with respect to the aluminum nitride. If the addition amount of the manganese component is too small, the wiring metal (for example, tungsten) cannot be sufficiently densified. On the other hand, if it is added in an excessively large amount, the wiring metal may be dissolved, the formation form may not be maintained, and the characteristics of the aluminum nitride substrate may be deteriorated.

Next, when a green sheet containing a manganese component is used, a normal wiring layer forming metal paste is applied in a desired wiring shape. Further, the through hole is filled with a wiring layer forming metal paste. The wiring layer forming metal paste is a high melting point metal powder such as tungsten to which an organic binder and a solvent are added and mixed to impart fluidity. When a green sheet containing no manganese component is used, the manganese component is added to the metal paste for forming the wiring layer, the manganese component is applied in a desired wiring shape, and the through hole is filled. When the manganese component is blended in the wiring layer forming metal paste, it is preferably about 1/10 to 1/50 of the amount when blended in the green sheet.

A necessary number of aluminum nitride green sheets coated with the wiring layer forming metal paste are laminated to produce an aluminum nitride compact. Next, after degreasing the aluminum nitride compact, it is fired in a non-oxidizing atmosphere such as a nitrogen atmosphere to simultaneously sinter the aluminum nitride base material and the wiring metal. In this way, the aluminum nitride multilayer wiring board 4 is obtained.

The aluminum nitride wiring board of the present invention can be applied to an aluminum nitride surface wiring board 7 in which a wiring metal layer 6 is provided on the surface of an aluminum nitride board 5, as shown in FIG. In this case, as in the case of the above-mentioned aluminum nitride multilayer wiring board, the surface wiring metal layer 6 is made of a metal mainly composed of it, such as tungsten,
Contains traces of manganese. Manganese exists as a composite with tungsten, and the composite containing tungsten and manganese contributes to the densification of the surface wiring metal layer 6, and makes the porosity of the surface wiring metal layer 6 2% or less, for example.
The manganese component is previously added to the aluminum nitride green sheet used to form the aluminum nitride substrate 5 and the metal paste used to form the surface wiring metal layer 6 as in the aluminum nitride multilayer wiring substrate. However, the present invention is particularly effective for an aluminum nitride wiring board having an internal wiring metal layer that is more difficult to densify.

As described above, also in the aluminum nitride surface wiring substrate 7, due to the presence of the composite containing at least the wiring metal and manganese, the surface wiring metal layer 6 having a sufficiently dense porosity of 2% or less. Is obtained. Further, the bondability between the aluminum nitride substrate 5 and the surface wiring metal layer 6 is also stabilized.

The fully densified surface wiring metal layer 6 as described above is not subjected to heat treatment or the like because liquid components and organic impurities do not enter the wiring layer when a plating layer or a thin film is formed thereon. It is possible to avoid defective factors such as generation of decomposed gas components and abnormal swelling. In addition, the surface wiring metal layer 6
Is an unnecessary substance that causes poor continuity and poor appearance, for example, does not contain an aluminum nitride component or a sintering aid component,
It has low resistance and excellent appearance.

Furthermore, the present invention can be applied to an aluminum nitride wiring board provided with both an internal wiring metal layer and a surface wiring metal layer, and the same densification effect can be obtained for any wiring layer.

Next, specific examples of the aluminum nitride wiring board of the present invention and the evaluation results thereof will be described.

Example 1 and Comparative Example 1 First, manganese dioxide powder having a purity of 99% was prepared as a manganese compound. The manganese dioxide powder was added to the aluminum nitride green sheet forming slurry at a ratio of 2.5 mol%, 0.75 mol% and 0.25 mol% with respect to aluminum nitride, respectively. The green sheet forming slurry was prepared by using aluminum nitride raw material powder containing 5% by weight of yttrium oxide as a sintering aid. Further, since the manganese dioxide powder has a coarse particle size, it was ground in a pot mill, sieved, and then mixed with a slurry for forming a green sheet. The required number of aluminum nitride green sheets were produced using each of the green sheet forming slurries.

A through hole was formed in each aluminum nitride green sheet, and the tungsten paste was filled in the through hole. Further, a tungsten paste was printed on the surface of the aluminum nitride green sheet.
Then, these aluminum nitride green sheets were laminated to produce laminated molded bodies. Each of these laminated compacts was degreased in a nitrogen stream. In the tungsten paste, the aluminum nitride component was not added, and the inorganic component was a paste containing only tungsten powder. This is to understand the effect of manganese dioxide on the wiring metal.

Thereafter, each degreased body is placed in a firing jig made of aluminum nitride, fired at 2093 K in nitrogen, and aluminum nitride and tungsten are fired at the same time to obtain aluminum nitride wiring boards. It was

In addition, as a comparative example with the present invention, a co-fired substrate of aluminum nitride and tungsten (aluminum nitride wiring board) was prepared under the same conditions as in the above-mentioned example except that manganese dioxide was not added to the aluminum nitride green sheet. It was made. The co-fired substrate of Comparative Example 1 was fired in the same furnace as in Example 1 at the same time.

In order to evaluate the internal sintering state and the like of the wiring metal layer (tungsten layer) of the aluminum nitride wiring boards according to Example 1 and Comparative Example 1 thus obtained, the respective cross-sectional structures were examined by scanning electron microscopy. It was observed under a microscope. Figure 3
3 is a scanning electron micrograph showing a sectional fine structure of an internal wiring portion of Example 1 (manganese dioxide powder added at a ratio of 2.5 mol%). FIG. 4 is a scanning electron micrograph showing the cross-sectional fine structure of the internal wiring portion of Comparative Example 1.

As is apparent from FIG. 3, in the aluminum nitride wiring board (Example 1) using the aluminum nitride green sheet to which manganese dioxide was added, the internal wiring portion was sufficiently densified, and pores and the like were formed. An integrated wiring metal layer with almost no defects is obtained. It was also confirmed that the wiring metal layer was well wetted with the surrounding aluminum nitride and had good adhesion. 0.75 manganese dioxide powder
Similarly, for aluminum nitride wiring boards using aluminum nitride green sheets added in the proportions of mol% and 0.25 mol%, the internal wiring portion has also been sufficiently densified, and an integrated wiring metal layer with few pores. It was confirmed that was obtained.

On the other hand, as is clear from FIG. 4, the aluminum nitride wiring board using the aluminum nitride green sheet to which manganese dioxide was not added had many pores in the internal wiring portion. Further, it is observed that the adhesion with the surrounding aluminum nitride is not good due to the existence of pores.

Further, the surface portion of the through hole of each aluminum nitride wiring board according to Example 1 and Comparative Example 1 was observed with an optical microscope (magnification: 500 times). FIG. 5 is an optical micrograph showing an enlarged microstructure of the surface of the through hole according to Example 1 (manganese dioxide powder added at a ratio of 2.5 mol%). Further, FIG. 6 is an optical micrograph showing an enlarged microstructure of the surface of the through hole according to Comparative Example 1.

From the comparison between FIG. 5 and FIG. 6, it is apparent that tungsten grain growth occurs in the through holes of the aluminum nitride wiring substrate (Example 1) to which manganese dioxide is added, and the densification is advanced.

As is apparent from FIG. 6, in the aluminum nitride wiring substrate according to Comparative Example 1, the grain growth of tungsten did not proceed sufficiently and a large number of pores were present. It was confirmed that the components and organic substances could easily enter. The penetration of such impurity components is
It is a direct cause of swelling of plating and generation of abnormal component gas during heat treatment when mounting a semiconductor element. In the aluminum nitride wiring substrate according to Example 1, since the wiring layer was densified, no impurity component permeated into the wiring metal layer, and no abnormality was observed in the heat treatment after plating. For each of the aluminum nitride wiring boards of Example 1 and Comparative Example 1 described above, a scanning electron micrograph of the cross section of the wiring metal layer was processed by image analysis, and the amount of pores remaining in the cross section of the internal wiring layer (residual pores Rate) was measured.
The residual porosity was determined in correspondence with each layer of the aluminum nitride multilayer substrate. The results are shown in Table 1.

[0046]

[Table 1] Further, the amount of constituent elements of the wiring metal layer of each aluminum nitride wiring board according to Example 1 and Comparative Example 1 was measured by EPMA analysis. The results are shown in Table 2.

[0047]

[Table 2] In addition, in the aluminum nitride wiring substrate in which the addition amount of manganese dioxide is 0.25 mol%, the Mn
Was not detected, which is considered to be based on the line analysis results. By the way, according to the surface analysis result of EPMA, it was confirmed that the Mn content was larger than that of Comparative Example 1 in which manganese dioxide was not added. Further, even in the aluminum nitride wiring board in which the amount of manganese dioxide added is 0.25 mol%, the wiring metal layer (tungsten layer) is sufficiently densified as described above, and the effect of adding manganese dioxide is obtained. There is.

The wiring metal layer of the aluminum nitride wiring board according to Comparative Example 1 contains Y or Al because the sintering (densification) of tungsten is slow, and this results from the sintering aid from the aluminum nitride substrate side. It is considered that the liquid phase component entered. On the other hand, Y or Al was not detected in the wiring metal layer of the aluminum nitride wiring board according to Example 1. From this, it can be seen that in Example 1, the sintering rate of tungsten was increased, and the tungsten was rapidly densified.

When the composition of the tungsten layer of the aluminum nitride multilayer wiring board according to Example 1 was analyzed by fine area X-ray diffraction, it was confirmed that a complex oxide of manganese and tungsten was produced.

Example 2, Comparative Example 2 An aluminum nitride green sheet forming slurry was prepared by using aluminum nitride raw material powder containing 5% by weight of yttrium oxide as a sintering aid, and this green sheet forming slurry was used. The required number of aluminum nitride green sheets were produced.

On the other hand, manganese dioxide powder having a purity of 99% was prepared as a manganese compound, and this manganese dioxide powder was added to a tungsten paste in an amount of 0.05% with respect to tungsten.
It was added and mixed at a ratio of mol%. Since the manganese dioxide powder has a coarse particle size, it was ground in a pot mill, sieved, and then mixed with a tungsten paste.

A through hole was formed in each aluminum nitride green sheet, and the tungsten paste containing the above manganese dioxide powder was filled in the through hole. Further, a tungsten paste was printed on the surface of the aluminum nitride green sheet. Next, these aluminum nitride green sheets were laminated to produce a laminated compact, and this laminated compact was degreased in a nitrogen stream.
In the tungsten paste, the aluminum nitride component was not added, and the inorganic component was a paste containing only tungsten powder. This is to understand the effect of manganese dioxide on the wiring metal.

Thereafter, the above-mentioned degreased body is placed in a firing jig made of aluminum nitride, fired at 2093 K in nitrogen, and aluminum nitride and tungsten are fired at the same time to obtain an aluminum nitride wiring board. It was

As a comparative example with the present invention, except that manganese dioxide is not added to the tungsten paste,
A co-fired substrate of aluminum nitride and tungsten (aluminum nitride wiring substrate) was produced under the same conditions as in the above-mentioned example. The co-fired substrate of Comparative Example 2 was fired in the same furnace as in Example 2 at the same time.

In order to evaluate the internal sintering state and the like of the wiring metal layer (tungsten layer) of each aluminum nitride wiring board according to Example 2 and Comparative Example 2 obtained in this way, the respective cross-sectional structures were scanned with a scanning electron. It was observed with a micrograph.
FIG. 7 is a scanning electron micrograph showing the cross-sectional fine structure of the internal wiring portion of Example 2. Further, FIG. 8 is a scanning electron micrograph showing the cross-sectional fine structure of the internal wiring portion of Comparative Example 2.

As is clear from FIG. 7, in the aluminum nitride wiring board (Example 2) using the tungsten paste containing manganese dioxide, the internal wiring portion was sufficiently densified, and pores and the like were almost eliminated. No integral wiring metal layer is obtained. It was also confirmed that the wiring metal layer was well wetted with the surrounding aluminum nitride and had good adhesion.

On the other hand, as is clear from FIG. 8, in the aluminum nitride wiring board using the tungsten paste to which manganese dioxide was not added, many pores were present in the internal wiring portion. Further, it is observed that the adhesion with the surrounding aluminum nitride is not good due to the existence of pores.

For each of the aluminum nitride wiring boards of Example 2 and Comparative Example 2 described above, a scanning electron micrograph of the cross section of the wiring metal layer was processed by image analysis, and the amount of pores remaining in the cross section of the wiring metal layer was processed. (Residual porosity) was measured. The residual porosity was determined in correspondence with each layer of the aluminum nitride multilayer substrate. The results are shown in Table 3.

[0059]

[Table 3]

[0060]

As described above, according to the present invention,
Since manganese and a manganese compound are added to the aluminum nitride green sheet or the metal paste for forming the wiring layer, the wiring metal layer can be densified without mixing the substrate components and the like with the wiring metal. further,
It is possible to stabilize the bonding between the aluminum nitride and the wiring metal. Therefore, poor continuity and appearance of the wiring metal layer,
Further, it is possible to prevent the occurrence of abnormal swelling of the plating layer or the thin film wiring layer formed on the wiring metal layer. As a result, it is possible to stably provide an aluminum nitride wiring board suitable for a semiconductor package, a circuit board, or the like.

[Brief description of drawings]

FIG. 1 is a sectional view schematically showing a configuration of an aluminum nitride wiring board according to an embodiment of the present invention.

FIG. 2 is a sectional view schematically showing the structure of an aluminum nitride wiring board according to another embodiment of the present invention.

FIG. 3 is a scanning electron micrograph showing an enlarged cross-sectional structure of an internal wiring layer portion of an aluminum nitride wiring board according to Example 1 of the present invention.

4 is a scanning electron micrograph showing an enlarged sectional structure of an internal wiring layer portion of an aluminum nitride wiring board according to Comparative Example 1. FIG.

FIG. 5 is an optical micrograph showing an enlarged surface microstructure of a wiring metal layer of an aluminum nitride wiring board according to Example 1 of the present invention.

FIG. 6 is an optical micrograph showing an enlarged surface fine structure of a wiring metal layer of an aluminum nitride wiring board according to Comparative Example 1.

FIG. 7 is a scanning electron micrograph showing an enlarged cross-sectional structure of an internal wiring layer portion of an aluminum nitride wiring board according to Example 2 of the present invention.

8 is a scanning electron micrograph showing an enlarged cross-sectional structure of an internal wiring layer portion of an aluminum nitride wiring board according to Comparative Example 2. FIG.

[Explanation of symbols]

 1 ... Aluminum nitride multilayer substrate 2 ... Aluminum nitride layer 3 ... Internal wiring metal layer 4 ... Aluminum nitride multilayer wiring substrate 5 ... Aluminum nitride substrate 6 ... Surface wiring metal layer 7 ... Aluminum nitride surface wiring substrate

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display area // H05K 3/12 B 7511-4E

Claims (8)

[Claims] 1. An aluminum nitride wiring board comprising: an aluminum nitride substrate; and a wiring metal layer provided on at least one of a surface and an inside of the aluminum nitride substrate and co-fired with the aluminum nitride substrate. The aluminum nitride wiring board, wherein the layer contains manganese in an amount of 2% by weight or less in addition to the metal mainly constituting the wiring metal layer. 2. An aluminum nitride wiring board comprising: an aluminum nitride substrate; and a wiring metal layer provided on at least one of a surface and an inside of the aluminum nitride substrate and having a porosity of 2% or less. 3. The aluminum nitride wiring board according to claim 2, wherein the constituent component of the wiring metal layer is made of a metal material that does not substantially contain an inorganic insulator. 4. The aluminum nitride wiring board according to claim 3, wherein the wiring metal layer is a baked metal layer co-fired with the aluminum nitride board. 5. The aluminum nitride wiring board according to claim 2, wherein the wiring metal layer contains manganese in an amount of 2% by weight or less. 6. A step of applying a wiring layer forming metal paste containing a wiring metal to a desired shape on an aluminum nitride green sheet and laminating one or more layers of the paste to produce an aluminum nitride molded body, A method of manufacturing an aluminum nitride wiring board, comprising a step of firing an aluminum nitride molded body to simultaneously sinter an aluminum nitride base material and the wiring metal, wherein the aluminum nitride green sheet and the wiring layer forming metal paste are provided. At least one manganese component selected from manganese and manganese compounds is added to at least one of the above. 7. The method for manufacturing an aluminum nitride wiring board according to claim 6, wherein the manganese component reacts with the wiring metal in the firing step to form a trace amount of a composite containing at least the wiring metal and manganese. A method for manufacturing an aluminum nitride wiring board, wherein a body is formed in the wiring metal. 8. The method for manufacturing an aluminum nitride wiring board according to claim 6, wherein a metal material containing tungsten as a main component is used as the wiring metal, and a manganese compound is used as the manganese component. Wiring board manufacturing method.