JPS625694A - Manufacture of multilayer interconnection substrate - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for manufacturing a multilayer wiring board used for high functionality, high performance, and high density mounting on which ICs, LSIs, and small passive components are mounted.

BACKGROUND OF THE INVENTION In recent years, the demand for smaller devices and more multifunctional devices has become stronger over the years. On the other hand, there has also been significant progress in high-speed signal processing technology. Under these circumstances, multilayer wiring board technology using ceramics is playing an important role as a board for high-density mounting of small devices and a board for high-speed device mounting. Conventionally, there are roughly two types of ceramic multilayer wiring board technologies (for example, Electronic Technology, Vol. 24, No. 4, pages 26-30).

One method is to print tungsten or molybdenum paste on green sheets made of an inorganic component mainly composed of alumina powder, an organic binder, and a plasticizer, then stack multiple sheets of these sheets and laminate them together using heat and pressure. Alternatively, tungsten or molybdenum paste and alumina beanite are sequentially printed and integrated on an aluminum carbureen sheet and sintered at high temperature in a reducing atmosphere. In multilayer boards obtained using this method, the surface layer of tungsten or molybdenum metal is usually plated with gold or other metal to prevent corrosion and enable soldering. The other method is also called the thick film printing method, in which a conductive paste (such as
This is a method in which printing, drying, and firing are repeated for each layer of glass paste (kg/Pd, Cu, etc.) and glass paste. Of this method, MuU.

The Ag/Pd conductor is fired at 850 to 90°C in air, and the Cu is fired at 860 to soo'C in a nitrogen atmosphere.

Problems to be Solved by the Invention However, of the two methods explained above, the green sheet method is unsuitable, and the use of alumina as a material for insulation has poor insulation properties.
Although it has the advantage of excellent thermal conductivity and the ability to increase the number of bond layers, it uses tungsten and molybdenum as the conductor material, so the conductor resistance of the wiring part is high (5 to 10 times that of Cu).
In addition to this disadvantage, the cost is high because the surface conductor layer must be plated with gold. However, since this method involves firing an unfired monolithic product, the dimensions after firing will vary, so there is also the drawback that sufficient accuracy in the wiring pattern cannot be achieved.

On the other hand, the thick film printing method is advantageous in that it allows the use of materials with sufficiently low conductor resistance, such as U or Cu, as a substrate for high-speed signal processing. It has the advantage of sufficient dimensional accuracy. However, in this method, printing, drying, and firing must be performed layer by layer to form the conductor and insulating layers, making the process time consuming. It has the disadvantage of not having sufficient characteristics and resulting in a decrease in yield. Among these methods, the method using Au is extremely expensive, and the use of Cu, which is a low cost and low conductor resistance material, is strongly desired.

In view of the above-mentioned problems, the present invention provides a method for manufacturing a multilayer wiring board including both low-resistance copper wiring and tungsten wiring layers at a low cost and having all the advantages of both the green sheet method and the thick film printing method. be.

Means for Solving the Problems In order to solve the above-mentioned problems, the method for manufacturing a multilayer wiring board of the present invention provides a method for manufacturing a multilayer wiring board of the present invention. In the hole, P
Alternatively, a process of filling a paste consisting of Pd or a mixed powder thereof, a low-melting glass that does not oxidize tungsten or molybdenum, and alumina powder, heat-treating it to make the filling dense, and applying copper oxide paste on top of this. A process of repeatedly printing and drying glass or a mixed powder paste of glass and ceramics, and a process of heat-treating this in air to remove the binder, then heat-treating it in a reducing atmosphere to turn copper oxide into copper metal, and then firing and densifying it. It is what it is.

Functions The present invention makes it possible to manufacture the multilayer wiring board of the present invention through the above-described steps for the following nine reasons.

According to the present invention, copper oxide is used as a starting material for forming a low resistance copper wiring layer. The reason why this copper oxide is used is because it is necessary to print the copper oxide layer and the insulating layer laminated together with it, so the raw material is prepared in the form of beanute, and the paste contains a large amount of organic binder. If this organic binder remains in the film in the form of subelements during the densification process, it will cause pinholes and bubbles, so it is desirable to completely remove it. Therefore, in the present invention, copper oxide is used as the starting material for the copper conductor layer, and after the organic binder is completely baked in air, it is reduced and further densified.

When a copper metal powder raw material is used as the conductor material, the binder must be removed in an atmosphere free of oxygen, such as a nitrogen atmosphere. Therefore, a small amount of binder remains in the film, degrading the insulation properties. Since the copper multilayer part of the present invention takes the above steps, the insulating layer is extremely dense and exhibits excellent insulating properties. On the other hand, tungsten or molybdenum is used as the conductor material for the internal laminated body. These materials are extremely stable in a reducing atmosphere, but when exposed to air, oxidation rapidly progresses from a temperature of about 400°C to 500°C, and they become volatile gases and disappear. Therefore, when forming a copper multilayer part as in the present invention involves treatment in air, the internal tungsten or molybdenum conductor layer is oxidized and becomes useless as a conductor. One of the important points in the present invention is to have a structure in which the internal tungsten or molybdenum layer can withstand such in-air heat treatment. As a means for achieving this, in the present invention, platinum (Pt)
Alternatively, a paste made by kneading palladium (Pd) or a mixture thereof, a low-melting glass powder made of components that do not oxidize tungsten or molybdenum, alumina powder, and organic beak/l is filled and heat-treated in air or nitrogen atmosphere. and refine the process. The purpose of this is to electrically connect the top layer and the inner layer for materials containing tungsten or molybdenum, and to prevent the inner layer from being oxidized even after heat treatment in air (72: Yes. In terms of materials, Pt''! or Pd or a mixture thereof acts as a conductor, while glass and alumina act to prevent oxygen from entering the inside.The heat treatment for densification in this filling machine is possible even in air. This is because the low melting point glass begins to flow and coat the surface before tungsten or molybdenum begins to oxidize in the process of temperature rise, preventing the reaction with external oxygen from proceeding.Also, there is lead oxide in the glass. It is preferable not to include a component such as (PbO).This is because if a component that is easily reduced such as lead oxide is included, tungsten and molybdenum will be easily oxidized and will not exhibit conductivity.

As explained above, in the present invention, a filling machine is formed in the small pores in the upper layer of the alumina fired substrate film having an inner layer of tungsten or molybdenum, and after a treatment that does not oxidize the inside even when heat-treated in air, an oxidized steel paste is applied. and glass powder or a mixture paste of this and seven umic powders are printed alternately,
After repeated drying, the binder is removed all at once in the air, and the process is further densified in a reducing atmosphere.
It is possible to integrate an alumina-tungsten or molybdenum multilayer structure with a copper-glass or glass-ceramics multilayer structure.

The composition of the filling machine is 60 to 90WX as a conductor component.
It is desirable that it be within the range of . This is because when the SOW% is less than the SOW%, sufficient conductivity cannot be obtained, and when the SOW% is more than the SOW%, it is not possible to completely prevent oxygen from entering the interior.

Example Examples are shown below.

Example 1 Consists of an insulating layer made of 92W% alumina containing sintering aid components such as silica and magnesia, and a tungsten conductor layer, with a plurality of minute portions (0.31ffllll angle) of the internal conductor layer exposed at the top. A laminated sintered body having an insulating layer formed with small holes as described above was prepared.

This is a laminate in which tungsten paste and alumina paste are alternately printed on alumina green sheets and dried repeatedly, and then fired at 1680° C. in a humid nitrogen-hydrogen mixed atmosphere. Table IK is shown in the small hole part of this laminated sintered body.
After screen-printing a paste with the ingredients shown, 1.
After drying in air at 00'C for 10 minutes, it was fired in air at 850C for 30 minutes using a thick film vector.

Note that the glass components shown in Table I soften at about 460'C.

Table I Filling machine composition Glass: BaO, B2O3 as main components, other 5in
2゜λ120. ．． Composition with MgO as an additive, softening time ~ 450'C At the top of this fired body, a paste obtained by kneading copper oxide powder and Tenbin oil dissolved in 10 W% ethyl cellulose was placed in contact with the Koten machine. The mixture was screen printed and dried, and then a paste obtained by kneading the glass powder-ceramic powder mixture consisting of the ingredients shown in Table 1 and the above ethyl cellulose-terepinol vehicle was screen printed and dried.

Note that printing of this insulating layer paste was performed twice.

Repeat the above steps so that the copper oxide layer becomes the top layer,
Printing was performed so that there were three copper oxide layers including this top layer. In the previous steps, we used a screen printing plate designed to connect the inner tungsten layer and the outer copper oxide layer with interlayer vias. This printed laminate was treated at 800°C in air for 15 minutes, in a mixed atmosphere of H2/N2 = 1o/90, at 450°C for 15 minutes, and subsequently heated to 1030°C in pure N2. After being held for 30 minutes, it was slowly cooled and taken out from the store.

Table H Insulating Paste 1 Geometric Inorganic Composition The substrate after firing is sintered as a dense structure, and the wiring resistance of the copper multilayer part is 2 to 3 mΩ2.

The interlayer insulation resistance of the copper conductor is 0.5 to I x 1 o 15Ω
Met. Note that the resistance of the tungsten conductor layer is 15 m.
It was about Ω/mouth. In addition, the resistance connecting the internal tungsten and copper metallized layer is extremely low and difficult to accurately evaluate, but the resistance value is the lowest when the amount of metal (Pt) is 75w%, and when the amount of metal (Pt) is 75w%, the resistance value is the lowest, and when The value was about 16 to 20 higher than that of the standard.

However, this value is so small that it poses no problem in practice. Moreover, when the inner layer was made of molybdenum, almost the same level of - was obtained as when using tungsten, and even when molybdenum was used for the inner layer conductor, the same effect as tungsten was obtained. .

As described in detail, the present invention involves forming a filling machine made of PT or Pd, low melting point glass, and alumina in an alumina-tungsten or molybdenum-based multilayer structure sintered body, and forming a filling machine made of PT or Pd, low melting point glass, and alumina. After repeatedly printing the base If, heat treatment in air, reducing atmosphere treatment, and densification treatment are performed all at once, resulting in a composite multilayer structure of alumina-tungsten or molybdenum-based glass or a ceramic mixture thereof-copper-based You get a body.

This makes it possible to combine an advanced multilayer construction method and a multilayer board with excellent thermal conductivity and a multilayer board with extremely low wiring resistance.In addition, since the copper multilayer board is printed on a sintered board, pattern accuracy is improved. It is also suitable for mounting parts that require high precision.

Claims (1)

[Claims] Platinum powder, palladium powder, A step of filling a paste consisting of 60 to 90 w% of one type or a mixture thereof, 40 to 10 w% of a frit component consisting of low melting point glass powder and alumina powder made of components that do not oxidize tungsten or molybdenum, and an organic vehicle; A step of firing this laminate in air or N_2 to densify the filled part, a step of printing a paste consisting of copper oxide powder and an organic vehicle, and a step of sintering the laminate at a temperature lower than the melting point of copper with glass powder or A process of printing and drying a paste consisting of a mixed powder of ceramic powder and an organic vehicle is repeated, a process of heat-treating this in air to remove the binder, and a process of heat-treating this in a reducing atmosphere to produce copper oxide. A method for producing a multilayer wiring board, comprising the steps of reducing copper metal to copper metal, and heat-treating this in a neutral or reducing atmosphere to sinter and densify the copper and oxide insulating layers.