JPS61111598A - Manufacture of glass ceramic multilayer circuit board - 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 the Invention The present invention relates to a method for manufacturing a glass-ceramic multilayer substrate that allows the formation of fine patterns and has good heat dissipation.

In response to the increasing speed and capacity of computers, the unit elements that make up semiconductor devices such as ICs and LSIs have been miniaturized.
Further, while the width of the conductor pattern for circuit connection between each element has been reduced, on the other hand, VLSI with a further increase in the number of elements has been put into practical use.

In addition, the method of mounting these semiconductor devices onto printed wiring boards has also progressed. Conventionally, semiconductor elements such as ICs and LSIs were individually packaged and packaged using through-holes provided on the printed wiring board. Previously, the mounting method was to weld them to the pads, but now multiple LSI chips are mounted on a ceramic printed wiring board, packaged as is or in bulk, and printed as a replacement unit. LSI mounted on wiring board
We are moving towards modules.

2. Description of the Related Art The following points are necessary for a ceramic circuit board on which a plurality of LSIs are mounted.

■Multi-layer structure with good heat conduction.

■It is possible to form fine conductor patterns.

■Excellent signal transmission characteristics.

That is, an LSI is formed with a large number of terminals, but since a plurality of such LSIs are mounted, the number of wires connected to the lead pins provided on the back surface of the ceramic circuit board becomes substantial.

For example, it is planned that 2,000 to 3,000 glue dowels will be attached to a 10 cm square circuit board.

Therefore, it is necessary for the circuit board to have a multilayer structure, and it is also necessary that the line width of the conductor pattern be extremely narrow.

Furthermore, such multilayer wiring is made up of signal lines, power supply lines, etc., and because the signal frequency is high, it is necessary that crosstalk between layers or wiring and signal delay be small.

Furthermore, in order to suppress heat generation in the wiring, the wiring pattern must have low resistance, and the circuit board must be made of a material with good thermal conductivity.

However, a ceramic circuit board that fully satisfies these conditions has not yet been put into practical use.

Conventionally, glass ceramic multilayer substrates have been put into practical use as circuit boards used for such purposes.

That is, a conductive paste mainly composed of copper (Cu) or gold (Au) is applied onto a glass-ceramic green sheet approximately 200 μm thick by screen printing to form a conductor pattern, and vias are formed at the required positions. It was formed by a green sheet lamination method in which holes are formed, a plurality of such green sheets are stacked, fired, and integrated.

The reason why glass ceramics are used here is that the dielectric constant is about 5, which is about 2, which suppresses crosstalk compared to conventional alumina, and that metals with low conductor resistance, such as A u + Cu, can be used.

In other words, the firing temperature of conventional alumina substrates is approximately 1600°.
C, and metallic elements with melting points near 1000°C, such as Au and Cu, cannot be used.

On the other hand, the firing temperature of glass ceramics is 900 to 1000° C., although it varies depending on the type of glass used, so AuJPCu paste can be used and a conductive pattern with low resistance can be formed.

However, since the conductor patterns of the multilayer substrate made in this manner are formed by screen printing, it is difficult to reduce the pattern width to 70 μm or less, and the limit for via holes is 80 μm.

As described above, although formation of fine patterns is necessary, the purpose has not been fully achieved.

[Problem that the invention seeks to solve]

An object of the present invention is to provide a circuit board suitable for high-density packaging by using a substrate material with good thermal conductivity and forming a narrow wiring pattern.

[Means for solving problems]

The above problem is solved by glass ceramics, which is characterized by forming a conductor pattern using a metal vapor deposition film on a glass ceramic multilayer substrate formed by the green sheet lamination method, and forming a multilayer circuit using nitride as an interlayer insulating layer. This can be achieved by a method for manufacturing a multilayer substrate.

[Effect]

A detailed study of the requirements for a ceramic circuit board used in an LSI module reveals that the present invention does not necessarily require a fine pattern in each layer of a multilayer structure, so the present invention uses a conventional board as is and does not require a fine pattern. The upper layer is insulated with nitride, and a wiring pattern is formed with a vapor-deposited film to realize a circuit board with a fine pattern.

In other words, the electrical and ground layers arranged in the center of the multilayer board do not need to have fine patterns, so they are formed by the conventional green sheet lamination method, and the signal layer formed thereon is formed using the present invention. The nitride is used for interlayer insulation, and the deposited film is used to form a fine pattern.

Here, in the present invention, the nitride used for interlayer insulation is aluminum nitride (AIN) or boron nitride (BN), while the material of the metal vapor deposition film is gold (AU) or copper (Cu).
), the latter being no different from conventional patterning materials.

AlN and BN are chemically stable compounds that have high thermal conductivity, relatively low dielectric constant, and are compared with oxides conventionally used for layer insulation.

As shown in the table, the thermal conductivity is much higher than that of conventional products.2. Therefore, the heat dissipation effect is excellent, and since BN has a low dielectric constant, there is little electrostatic induction, so crosstalk can be suppressed.

Next, regarding chemical stability, AI N undergoes oxidation at 1700°C, but oxidation progresses only slightly when heated to 1200°C, and BN is stable at temperatures up to 00'C. Acid (H) progresses from 980℃ (C
tligh-Temperature by ampbell
e Materials and Technology
13.3. l, 243p).

Here, since the semiconductor device is maintained at a maximum operating temperature of 85"C to maintain reliability, it can be said that these nitrides can be used stably.

〔Example〕

The present invention uses a glass-ceramic multilayer substrate formed by the green sheet lamination method as a substrate, and a multilayer circuit is formed thereon.

Hereinafter, a method for forming a multilayer circuit will be described with reference to an embodiment.

Example 1 Glass ceramic single layer thickness approximately 200 μm + C
A conductor pattern is formed by vapor depositing Cu using a mask on a glass ceramic multilayer substrate formed in a 201 configuration with a U conductor layer thickness of approximately 25 μm, and then an AI N interlayer insulating layer is formed on this by sputtering. Then, via holes were formed using photolithography, and this process was repeated to form a multilayer circuit consisting of five layers.

Here, the sputtering conditions are A
The test was carried out using a tN disk as the counter electrode and the degree of vacuum of argon (Ar) gas was 10-' to 10'''Toor.
It was formed to a thickness of pm.

Further, the radius of the Cu4 body pattern and the diameter of the via hole are both 20 IIm.

The multilayer board thus formed satisfies the requirements for a ceramic circuit board on which an LSI is mounted, and has a speed of 70 ps/am.
It was possible to achieve a transmission delay time of .

Example 2 A conductive pattern was formed by depositing Au using a mask on a glass ceramic substrate with a 20-layer structure in which the glass ceramic substrate had a thickness of 200 μm and the Au conductor layer had a thickness of about 25 μm, and then a conductive pattern was formed on this by chemical vapor deposition. An interlayer insulating layer made of BN is formed by a phase epitaxy (CVr) method, and a photo-etched wave jrlj
A via hole was formed using the same method, and this process was repeated to form a multilayer circuit consisting of five layers.

Here, the CVD conditions for forming BN are as follows: A mixed gas of boron chloride (BCl2) and ammonium chloride (NH4C1) is used as the reaction gas, and the gas flow rate is adjusted to 5 liters per minute.
The reaction was carried out at a temperature of 700°C to grow BN on the substrate.

The growth rate in this case was about 0.25 μm/H, and an insulating layer of 0.2 μm was formed using this method.

Further, the width of the Aug body pattern and the diameter of the via pole are both 20 μm.

The ceramic multilayer board thus formed satisfied the requirements for a ceramic circuit board on which an LSI is mounted, and was also able to achieve a transmission delay time of 70 PS/cm.

〔Effect of the invention〕

As explained above, by implementing the invention in which a conductor pattern is formed using a metal vapor deposited film and an interlayer insulating layer is formed using nitride on a conventional glass-ceramic multilayer substrate, heat conduction is improved. AJ: Multilayer substrates with fine conductor patterns can be made.

Claims (5)

[Claims] (1) A glass ceramic multilayer substrate formed by a green sheet lamination method, on which a conductor pattern is formed using a metal vapor deposition film and a multilayer circuit is formed using nitride as an interlayer insulating layer. manufacturing method. (2) The method for manufacturing a glass-ceramic multilayer substrate according to claim 1, wherein the nitride is made of aluminum nitride. (3) The method for manufacturing a glass-ceramic multilayer substrate according to claim 1, wherein the nitride is made of boron nitride. (4) The method for manufacturing a glass-ceramic multilayer substrate according to claim 1, wherein the constituent material of the metal vapor deposited film is made of copper. (5) The method for manufacturing a glass-ceramic multilayer substrate according to claim 1, wherein the constituent material of the metal vapor deposited film is made of gold.