JPS6355238B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] 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. ICs and LSIs respond to faster speeds and larger capacity computers.
In semiconductor devices such as these, the unit elements that make up these devices have been miniaturized, and the width of the conductor patterns that connect circuits between each device has been reduced. On the other hand, VLSI, which has a further increase in the number of elements, has been put into practical use. In addition, the mounting method of these semiconductor devices on printed wiring boards has also progressed, and in the past, semiconductor elements such as ICs and LSIs were individually packaged and packaged.
Previously, this was mounted by welding to through holes or pads provided on the printed wiring board, but now multiple LSI chips are mounted on a printed wiring board made of ceramic, and can be mounted as is or in bulk. LSI is packaged and mounted on a printed wiring board as a replacement unit.
There is a shift towards modules. The present invention relates to a method of manufacturing a ceramic circuit board suitable for such purposes. [Prior Art] The following points are necessary conditions for a ceramic circuit board on which a plurality of LSIs are mounted. Multi-layer structure with good heat conduction. Capable of forming fine conductor patterns. Excellent signal transmission characteristics. In other words, an LSI is formed with a large number of terminals, and since a plurality of such LSIs are mounted, the number of circuit connections to the lead pins provided on the back side of the ceramic circuit board becomes enormous. For example, it is planned that 2,000 to 3,000 lead pins will be attached to a 10cm square circuit board. Therefore, the circuit board needs to have a multilayer structure, and the line width of the conductor pattern needs to be extremely narrow. In addition, such multilayer wiring is composed of signal lines, power supply lines, etc., but because the signal frequency is high, it is necessary to have little crosstalk and signal delay between layers or wiring. . 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. In other words, a conductive paste mainly composed of copper (Cu) or gold (Au) is applied onto a glass-ceramic green sheet approximately 200 μm thick using a screen printing method to form a conductor pattern, and vias are placed 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 glass ceramics are used here is that their dielectric constant is around 5, which is about 1/2 that of conventional alumina.
crosstalk can be suppressed to a minimum, and Au,
This is because metals with low conductor resistance such as Cu can be used. In other words, the firing temperature of conventional alumina substrates is approximately
The temperature is as high as 1,600℃, and metal elements such as Au and Cu, which have melting points around 1,000℃, cannot be used. On the other hand, the firing temperature for glass ceramics is 900 to 1000℃, although it varies depending on the type of glass it is made of.
Therefore, Au or Cu paste can be used and a conductor pattern with low resistance can be formed. However, since the conductor patterns of the multilayer substrates made in this way 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. [Problems to be Solved by the Invention] 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 wiring pattern with a narrow pattern width. [Means for solving the problem] The above problem can be solved by using a multilayer circuit using a conductor pattern using a metal vapor deposition film and a nitride as an interlayer insulating layer on a glass ceramic multilayer substrate formed by the green sheet lamination method. This can be achieved by a method for manufacturing a glass-ceramic multilayer substrate, which is characterized by forming a glass-ceramic multilayer substrate. [Function] When the requirements for ceramic circuit boards used in LSI modules are carefully examined, it is found that fine patterns are not necessarily required for each layer in a multilayer structure. The upper layer requiring a pattern 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, since the power supply layer and the ground layer placed in the center of the multilayer board do not need to have fine patterns, 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 (AlN) or boron nitride (BN), while the material of the metal vapor deposition film is gold (Au) or copper (Cu), the latter being aluminum nitride (AlN) or boron nitride (BN). No different from traditional pattern forming materials. AlN and BN have high thermal conductivity, relatively low dielectric constant, and are chemically stable compounds.
A comparison of this with oxides conventionally used for layer insulation is as follows.

〔Example〕

The present invention uses a glass ceramic multilayer substrate formed by a green sheet lamination method as a substrate, and a multilayer circuit is formed on this substrate. Hereinafter, a method for forming a multilayer circuit will be described with reference to an embodiment. Example 1 A conductive pattern was formed by depositing Cu using a mask on a glass-ceramic multilayer substrate consisting of 20 layers, with a glass-ceramic single layer approximately 200 μm thick and a Cu conductor layer approximately 25 μm thick. An AlN interlayer insulating layer was formed thereon by sputtering, via holes were formed using photolithography, and this process was repeated to form a multilayer circuit consisting of five layers. Here, the sputtering conditions were such that an AlN disk formed by hot pressing was used as a counter electrode, the vacuum degree of argon (Ar) gas was 10 ^-1 to ^{10 -3} Torr, and the thickness was 0.5 μm. Furthermore, the width of the Cu conductor pattern and the diameter of the via hole are both 20 μm. The multilayer board formed in this way satisfies the requirements for a ceramic circuit board on which an LSI is mounted.
We were able to achieve a transmission delay time of 70 ps/cm. Example 2 A conductive pattern was formed by depositing Au using a mask on a glass ceramic substrate with a 20-layer structure consisting of a glass ceramic single layer with a thickness of 200 μm and an Au conductor layer with a thickness of about 25 μm. An interlayer insulating layer made of BN was formed using a chemical vapor deposition method (CVD method), via holes were formed using photolithography, and this process was repeated to form a multilayer circuit consisting of five layers. Here, the CVD conditions for forming BN are boron chloride (BCl ₃ ) and ammonium chloride (NH ₄ Cl) as reaction gases.
Using a mixed gas of
BN grew. The growth rate in this case is approximately 0.25μm/H,
A 0.2 μm insulating layer was formed using this method. Furthermore, the width of the Au conductor pattern and the diameter of the via hole are both 20 μm. The ceramic multilayer substrate formed in this way is
It satisfies the requirements for the ceramic circuit board on which the LSI is mounted, and can achieve a transmission delay time of 70PS/cm. [Effects of the Invention] As explained above, by implementing the present invention in which a conductor pattern is formed using a metal vapor deposition film and an interlayer insulating layer is formed using a nitride on a conventional glass-ceramic multilayer substrate, good heat conduction can be achieved. Furthermore, multilayer substrates with fine conductor patterns can be made.

Claims (1)

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