JPS60171781A - Method of producing low dielectric constant multilayer 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 (a) Technical Part 11' of the Invention The present invention relates to a method for manufacturing a multilayer wiring board formed using a dielectric material with a low dielectric constant.

(b) Background of the Technology As a method for achieving higher speeds, efforts are being made to make the electronic circuit elements used smaller and larger in capacity.

Here, typical circuit elements are semiconductor elements such as LS, 1, etc., and the degree of integration is increasing due to miniaturization of unit elements.

In this case, the semiconductor element is mounted on a heat-resistant substrate such as ceramic, and in the case of a conventional mounting method, a hermetic seal is applied to form a semiconductor device, which is mounted on a printed wiring board.

Furthermore, as a mounting method in the future, a method of directly mounting a chip-shaped semiconductor element onto a heat-resistant insulating substrate such as a ceramic substrate is likely to be adopted.

Here, when mounting a semiconductor element such as an LSI or a VLSI with a higher degree of integration onto a heat-resistant insulating substrate, it is necessary to use a multilayer wiring board because the number of terminals is large.

The present invention relates to a method for manufacturing a multilayer substrate used for such purpose.

(C) Conventional technology and problems Conventionally, ceramics containing alumina have been used as multilayer wiring boards on which semiconductor devices are mounted, and conductive metals such as molybdenum-manganese (Mo-Mn) alloys and tungsten-manganese (W) have been used as conductor metals.・High melting point metals such as Mn) alloys are used.

The reason for this is that the sintering temperature of alumina (αA 12.03) is extremely high at several hundred degrees, which exceeds the melting point of commonly used conductive metals such as gold (Au) and copper (Cu).

For applications that require high-speed calculations, such as semiconductor elements used in computers, the conventional multilayer board structure has problems, and it is necessary to lower the dielectric constant of the board material and lower the resistance of the conductor pattern. Is required.

In other words, capacitance exists between the wiring patterns of the multilayer board, and this capacitance value is proportional to the area of the opposing wiring patterns and inversely proportional to the distance.

Therefore, as the number of layers of the multilayer wiring board increases and the thickness of each layer decreases, the capacitance between the wiring backs increases, the amount of crosstalk increases, and high-speed propagation of signals becomes difficult.

Furthermore, in response to the increase in the degree of integration of semiconductor devices, it is necessary to reduce the conductor pattern width, and it is necessary to commercialize conductor patterns of about 100 μm, but in order to realize this, it is necessary to reduce the width of conductor patterns, which is much more difficult than conventional conductor materials. It is necessary to use metals with low resistance.

In order to solve these problems, practical use of glass substrates, crystallized glass substrates, etc. in which alumina is dispersed is underway.

However, for borosilicate glass and crystallized glass with alumina added, the firing temperature is low (Au and Cu can be used, but the dielectric constant is still high at 5 to 8, and it is desired to put a substrate with an even lower dielectric constant into practical use. ing.

(d) Purpose of the Invention The purpose of the present invention is to form a substrate using an insulating material with a low dielectric constant, and to form an LSI or VLSI using a conductive material with a low resistance.
It is an object of the present invention to provide a method for manufacturing a multilayer wiring board suitable for mounting semiconductor elements such as the above.

(e) Structure of the Invention The object of the present invention is to provide a multilayer wiring board in which a wiring pattern is formed using a conductive metal with a low resistivity and a heat-resistant material with a low dielectric constant, the volume ratio of which is 10 to 70. % of quartz glass and glass with a low dielectric constant as the main constituent material, the sheets are stacked and pressed, and then fired at a temperature of 1100°C or less to uniformly disperse the silica glass. This can be realized by a method for manufacturing a low dielectric constant multilayer board, which is characterized by manufacturing a glassy multilayer wiring board.

(f) Embodiments of the Invention The present invention takes advantage of the fact that quartz glass has a low dielectric constant of 3.8 and has excellent electrical and mechanical properties such as a coefficient of thermal expansion and an insulation resistance value. By mixing and firing a low dielectric constant glass such as borosilicate glass with a small dielectric constant of 4.6 to create a substrate, it is possible to lower the firing temperature to below 1ioo°C. The melting point is tio.

This makes it possible to use conductive metals with temperatures below 0.degree. C., thereby achieving the above object.

The present invention will be described below with reference to Examples.

The table shows the raw material compositions used to make the glasses of Examples.

In this example, acrylic resin was used as the binder, and methyl ethyl ketone was used as the organic solvent.

These materials were thoroughly mixed and then kneaded to form a slurry, which was then molded into a green sheet with a thickness of 300 μm using a doctor blade method.

Next, this sheet was punched out into 1501 square centimeters, via balls were formed at the required positions, and copper paste was screen printed to form a wiring pattern with a width of 100 μm.

The 10 green sheets made in this way were laminated with precise alignment, then pressurized at 20 MPa for 30 minutes to integrate them, and then stacked on top of each other for 30 minutes at a temperature of 1000°C in a nitrogen stream. A multilayer substrate was obtained by firing.

The dielectric constant of the substrate thus obtained is 4.0, which is close to 3.8 of quartz glass, while the sheet resistance of the wiring pattern is as low as 1.1+mΩ.

The figure shows the relationship between density and dielectric constant of substrates made with the same composition as in the example but with different composition ratios of quartz glass and borosilicate glass.

That is, as the quartz content increases, the dielectric constant of the substrate approaches 3.8 of quartz glass, but on the other hand, when the quartz glass content exceeds 70%, the density of the substrate decreases rapidly and becomes porous.

Note that it is easier to manufacture the substrate if the content of quartz glass is small. Therefore, the multilayer substrate may be manufactured by selecting the silica glass content in the range of 10 to 70% depending on the application.

(g) Effects of the Invention The present invention provides a substrate with a low dielectric constant and low resistivity as a result of an increase in the number of constituent layers and thinner layer thicknesses as the degree of integration of semiconductor elements mounted on a multilayer wiring board increases. This was made in response to requests for features featuring wiring patterns, and implementation of the present invention makes it possible to put a substrate with a low dielectric constant into practical use.

[Brief explanation of drawings]

The figure is a diagram showing the relationship between dielectric constant and density with respect to quartz content in an example of the present invention.

Claims (1)

[Claims] In a multilayer wiring board that uses a conductive metal with low resistivity to form a wiring pattern and uses a heat-resistant material with a low dielectric constant, silica glass with a constituent volume ratio of 10 to 70% and glass with a low dielectric constant are used. A glassy multilayer wiring board in which silica glass is uniformly dispersed is produced by forming a green sheet using a mixture of the above as the main constituent material, laminating the sheets, applying pressure, and then firing at a temperature of 1100°C or less. A method for manufacturing a low dielectric constant multilayer substrate.