JPH0664991A - Method for cladding aluminum nitride-based sintered compact with metallic layer - Google Patents

Abstract

PURPOSE:To provide a method for cladding an aluminum nitride-based sintered compact with a metallic layer in which the surface of the aluminum nitride- based sintered compact can firmly be clad with the metallic layer. CONSTITUTION:The objective method for cladding the surface of an aluminum nitride-based sintered compact 10 with a metallic layer 14 comprises clading the surface of an aluminum nitride-based sintered compact 10 with the first layer 11 composed of at least one of an aluminum, a silicon and a titanium alkoxides and the second layer 12 composed of mixed powder obtained by adding glass powder to metallic powder, then burning the resultant layers, forming an oxide film 13 composed of at least one of aluminum oxide, silicon oxide and titanium oxide and simultaneously joining the metallic powder through glass to the oxide film 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for depositing a metal layer on an aluminum nitride sintered body.

[0002]

2. Description of the Related Art Conventionally, ceramics, particularly oxide-based ceramics typified by alumina, are excellent in characteristics such as electrical insulation and chemical stability. , A resistor, a capacitor, etc. are mounted and connected to a circuit board or the like, and a semiconductor element housing package or a circuit board or the like using the oxide-based ceramic has a large number of metal layers as circuit wiring conductors on the surface of the ceramic body. , Adhered and bonded.

The metal layer on the surface of the ceramic body made of such oxide ceramics, when the ceramic body is made of an alumina sintered body, usually contains an organic solvent and a solvent added to a powder of tungsten having an average particle size of about 2.0 μm. Then the paste-like one is applied to the surface of the unfired alumina-based compact by a screen printing method, and then the unsintered alumina-based compact is fired at a temperature of about 1600 ° C. in a reducing atmosphere, and then tungsten. By transferring a part of the glass component existing between the alumina crystals of the alumina sintered body between the powder particles of the powder, and bonding the alumina crystal and the tungsten powder through the glass component, the surface of the alumina sintered body is bonded. Adhered and bonded.

However, in recent years, the density and integration of semiconductor elements have rapidly increased, and the amount of heat generated during operation of the semiconductor elements has become extremely large.
Therefore, when this semiconductor element is housed and mounted in the conventional semiconductor element housing package or circuit board described above, the thermal conductivity of the alumina-based sintered body used for the package or circuit board is about 20 W / mK. Since it is low, the heat generated by the semiconductor element during operation cannot be well dissipated into the atmosphere through the alumina-based sintered body, and as a result, the semiconductor element becomes high temperature due to the heat generated by the element itself, This has caused a defect that the semiconductor element is thermally destroyed or the characteristics are thermally changed to cause a malfunction.

Therefore, in order to eliminate the above-mentioned drawbacks, an oxide-based ceramic such as an alumina-based sintered body is used instead of an oxide-based ceramic to improve the thermal conductivity.
It is conceivable to use an aluminum nitride-based sintered body of 80 W / m K or more, which is extremely easy to transfer heat.

[0006]

However, since the aluminum nitride sintered body has a small amount of glass components interposed between the aluminum nitride crystals and the wettability between the aluminum nitride crystals and the metal is poor, the aluminum nitride sintered body is not formed. Even if a metal layer made of tungsten powder or the like is bonded to the surface of the body, the bonding strength is extremely weak, and it has a drawback that it cannot be used for a package for housing a semiconductor element, a circuit board or the like.

[0007]

SUMMARY OF THE INVENTION The present invention has been devised in view of the above-mentioned drawbacks, and an object thereof is to provide an aluminum nitride-based sintered body capable of firmly depositing a metal layer on the surface of the aluminum nitride-based sintered body. It is to provide a method of depositing a metal layer.

[0008]

A method of depositing a metal layer on an aluminum nitride sintered body according to the present invention comprises at least one of aluminum, silicon and titanium alkoxides on the surface of the aluminum nitride sintered body, A mixed powder obtained by adding glass powder to metal powder is applied and then fired to form an oxide film of at least one of aluminum oxide, silicon oxide and titanium oxide on the surface of the aluminum nitride sintered body. It is characterized in that a metal layer is adhered to the surface of the aluminum nitride sintered body by forming and bonding metal powder to the oxide film via glass.

[0009]

The present invention will now be described in detail with reference to the accompanying drawings. FIG. 1 shows an embodiment in which an aluminum nitride sintered body having a metal layer manufactured by the method of the present invention is applied to a semiconductor element housing package for housing a semiconductor element, and 1 is aluminum nitride sintered material. An insulating base body 2 and a lid 2. The insulating base body 1 and the lid body 2 constitute a container for housing a semiconductor element.

The insulating base 1 is provided with a mounting portion 1a on which the semiconductor element 3 is mounted in the center of the upper surface thereof.
The semiconductor element 3 is adhered and fixed on the upper side with an adhesive such as glass or resin.

The insulating base 1 is made of an aluminum nitride sintered body, and the aluminum nitride sintered body has a high thermal conductivity of 80 W / m.multidot.K or more and is easy to conduct heat. When the semiconductor element 3 is attached to the
The insulating substrate 1 can directly conduct and absorb the heat generated by the semiconductor element 3 and can well dissipate the absorbed heat into the atmosphere, whereby the semiconductor element 3 is always destroyed by heat at a low temperature, It does not cause a thermal change and malfunction.

Further, a plurality of linear metal layers 4 as circuit wiring conductors are adhered and formed on the insulating substrate 1 from the periphery of the mounting portion 1a on which the semiconductor element 3 is mounted to the outer peripheral edge. The electrode of the semiconductor element 3 is electrically connected to the peripheral portion of the semiconductor element mounting portion 1a of the metal layer 4 via the bonding wire 5, and the external lead connected to the external electric circuit is connected to the outer peripheral end. Terminal 6 is attached via a brazing material such as silver solder.

The metal layer 4 acts as a conductive path for connecting each electrode of the semiconductor element 3 to an external electric circuit, and copper,
It is made of metal powder such as silver-palladium.

The metal layer 4 has nickel on its surface.
Layering a metal such as gold with good conductivity and corrosion resistance and good wettability with the brazing material to a thickness of 1.0 to 3.0 μm can effectively prevent oxidative corrosion of the metal layer 4. In addition, the connection between the metal layer 4 and the bonding wire 5 and the brazing between the metal layer 4 and the external lead terminal can be made extremely strong. Therefore, it is preferable to deposit nickel, gold or the like on the surface of the metal layer 4 in a thickness of 1.0 to 3.0 μm.

The external lead terminals 6 brazed to the metal layer 4 have the function of connecting the semiconductor element 3 housed therein to an external electric circuit, and by connecting the external lead terminals 6 to the external electric circuit. The semiconductor element 3 housed inside is connected to an external electric circuit via the metal layer 4 and the external lead terminal 6.

The external lead terminal 6 is made of, for example, an alloy of 51.0 to 64.0% by weight of iron, 29.0 to 34.0% by weight of nickel and 7.00 to 15.0% by weight of cobalt, and its thermal expansion coefficient is 4.0 to 5.0 × 10 ^-6 / ° C. (20-400 ℃).

The external lead terminal 6 has a coefficient of thermal expansion
4.0 to 5.0 × 10 ^-6 / ℃ (20 to 400 ℃), the thermal expansion coefficient of the aluminum nitride sintered body that constitutes the insulating substrate 1
(4.2 to 4.7 × 10 ^-6 / ° C) is similar to that when the external lead terminals 6 are brazed to the metal layer 4 adhered to the insulating base 1, the insulating base 1 and the external lead terminals 6 A large thermal stress due to the difference in thermal expansion coefficient between the two does not occur between them, and a large stress does not exist in the brazed portion between the two. Therefore, after brazing, the external lead terminals 6
Even if an external force is applied to the external lead terminal 6, the external force becomes large in proportion to the internal stress of the brazing portion, and the external lead terminal 6 is not peeled off from the insulating base 1.

Thus, according to the above-mentioned package for accommodating semiconductor elements, the semiconductor element 3 is attached to the upper surface of the insulating substrate 1 with an adhesive agent, and each electrode of the semiconductor element 3 is attached to the metal layer 4 with the bonding wire 5 interposed. Electrical connection,
After that, the lid 2 is bonded to the upper surface of the insulating base 1 via a sealing material such as glass or resin, and the semiconductor element 3 is hermetically sealed inside the container composed of the insulating base 1 and the lid 2. The final product is a semiconductor device.

Next, a method of depositing a metal layer on the upper surface of the insulating substrate used for the above-mentioned package for accommodating semiconductor elements, that is, the aluminum nitride sintered body will be described with reference to FIG.

First, as shown in FIG. 2 (a), a plate-shaped aluminum nitride sintered body 10 is prepared. The aluminum nitride sintered body 10 is, for example, yttrium oxide as a main raw material powder yttrium oxide as a sintering aid, powders such as calcia and a suitable organic solvent, a solvent is added and mixed to form a sludge. The sludge is made into a ceramic green sheet (ceramic green sheet) by adopting a doctor blade method, a calendar roll method, etc.After that, the ceramic green sheet is appropriately punched and a plurality of these are laminated, It is manufactured by firing at high temperature (about 1800 ℃).

Next, as shown in FIG. 2B, a first layer 11 made of at least one of aluminum, silicon and titanium alkoxide is formed on the upper surface of the aluminum nitride sintered body 10.
And a second layer 12 made of a mixed powder in which glass powder is added and mixed with metal powder are sequentially deposited.

The alkoxides of aluminum, silicon and titanium forming the first layer 11 become aluminum oxide, silicon oxide and titanium oxide which have good bonding property with glass when heat is applied. 2 layers
It serves as a base layer when 12 metal powders are bonded together via glass.

The first layer 11 made of at least one of alkoxides of aluminum, silicon, and titanium is, for example, aluminum nitride alkoxide, and a paste obtained by adding and mixing a suitable acid, water, organic solvent, and solvent. The entire surface of the upper surface of the sintered compact 10 is printed and applied to a thickness of 0 to 20.0 μm by the well-known spin coating method or screen printing method, and this is heated to 60 to 350 ° C for 10 to 30 ° C.
Aluminum nitride sintered body 10 by drying for 10 minutes
Applied to the upper surface of.

As the alkoxides of aluminum, silicon and titanium, aluminum triethoxide,
Tetraethoxysilane, titanium tetraethoxide,
Aluminum trimethoxide, tetramethoxysilane,
Titanium tetramethoxide or the like is used.

A second layer 12 made of a mixed powder of metal powder and glass powder is deposited on the first layer 11,
The metal powder of the second layer 12 forms a metal layer as a circuit wiring conductor, and the glass powder serves to bond the metal layer to the surface of the aluminum nitride sintered body 10.

[0026] The second layer 12 is copper powder or silver over palladium powder is preferably used as the metal powder, and as the glass powder for example, BaO over B ₂ O ₃ over SiO ₂ system, SrO chromatography
B ₂ O ₃ -SiO ₂ system, SiO ₂ -CaO -Al ₂ O ₃ system, Ta ₂ O
₅ -B ₂ O ₃ -SiO ₂ -Co glass type 1 or 2
A mixture of two or more species is used.

The second layer 12 is formed by adding metal powder and glass powder into a paste by adding an appropriate organic solvent and solvent, and applying the well-known screen printing method to the aluminum nitride sintered body 10. It is deposited on the surface of the upper first layer 11 in a predetermined pattern and with a thickness of 10.0 to 25.0 μm.

Next, the aluminum nitride sintered body 10 having the first layer 11 and the second layer 12 deposited on the upper surface is fired at a temperature of 600 to 1000 ° C., and the surface of the aluminum nitride sintered body 10 is Aluminum oxide is formed by forming an oxide film 13 made of at least one of aluminum oxide, silicon oxide, and titanium oxide, and bonding a metal layer 14 made of metal powder of the second layer 12 to the oxide film 13 via glass. A metal layer 14 is adhered to the surface of the sintered compact 10 to serve as an insulating base used in a package for housing a semiconductor element, a circuit board, or the like. In this case, since a dense oxide film 13 having good wettability with glass such as aluminum oxide, silicon oxide, and titanium oxide is formed on the surface of the aluminum nitride sintered body 10, the metal layer 13 is made of glass. It is bonded very strongly through the surface and does not easily peel off even when an external force is applied. Therefore, it can be used very suitably for a package for housing a semiconductor element, a circuit board, and the like.

The present invention is not limited to the above-mentioned embodiments, but various modifications can be made without departing from the gist of the present invention. For example, in the above-mentioned embodiments, aluminum nitride based sintering is possible. Although the first layer 11 made of at least one of aluminum, silicon and titanium alkoxide is deposited on the entire upper surface of the body 10, it may be deposited only in the region where the metal layer 14 is deposited.

[0030]

The method of depositing a metal layer on the aluminum nitride sintered body of the present invention, that is, at least one of aluminum, silicon and titanium alkoxides on the surface of the aluminum nitride sintered body, and a metal powder According to the method of depositing the mixed powder to which the glass powder is added and firing the same to deposit the metal layer on the surface of the aluminum nitride sintered body, the surface of the aluminum nitride sintered body is wettable with the glass. Since a dense oxide film of aluminum oxide, silicon oxide, titanium oxide, etc. having good heat resistance is formed and the metal layer is bonded to the oxide film via glass, the metal layer is adhered to the aluminum nitride sintered body. The strength becomes extremely strong, and as a result, even if an external force is applied to the metal layer, the metal layer is never easily peeled off from the aluminum nitride sintered body.

Therefore, the aluminum nitride-based sintered body to which the metal layer is applied, which is manufactured by the method of the present invention, can be used very suitably for a package for housing a semiconductor element, a circuit board, and the like.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example in which an aluminum nitride sintered body having a metal layer manufactured by the method of the present invention is applied to a semiconductor element housing package for housing a semiconductor element.

FIG. 2 is a cross-sectional view of each step for explaining a method of depositing a metal layer on the aluminum nitride sintered body of the present invention.

[Explanation of symbols]

10 ... Aluminum nitride sintered body 11 ... First layer made of at least one kind of alkoxide of aluminum, silicon and titanium 12 ... Second layer made of mixed powder of metal powder and glass powder 13. ..Oxide film 14 ... Metal layer

Claims (1)

[Claims] 1. A surface of an aluminum nitride sintered body is coated with at least one of alkoxides of aluminum, silicon and titanium and a mixed powder of glass powder added to metal powder, which is then fired. Forming an oxide film of at least one of aluminum oxide, silicon oxide and titanium oxide on the surface of an aluminum nitride sintered body, and bonding metal powder to the oxide film through glass to sinter the aluminum nitride sintered body. A method for depositing a metal layer on an aluminum nitride sintered body, which comprises depositing a metal layer on the body surface.