JP2871613B2 - Multi-chip module substrate and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a substrate for a multichip module and a method for manufacturing the same, and more particularly to a structure of a multichip module in a multilayer substrate used for a microwave integrated circuit for a microwave communication device.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 4, a multi-chip module of this type has at least two or more multilayer dielectric substrates and three or more conductor layers, and transmits a microwave signal to an inner layer. It has a stripline for transmission.

In FIG. 4, reference numeral 20 denotes a heat sink and carrier (made of metal) of a multi-chip module, 21 denotes an inner layer capacitor, 22 denotes a heat dissipation via hole, 23 denotes an inner layer resistor, 24 denotes a semiconductor chip, and 25 denotes a high frequency shield via. A hole 26 is a cap for hermetically sealing a cavity in which the semiconductor chip 24 is mounted, and 27 is a microstrip line formed by thick film printing.

[0004] The portion on which the semiconductor chip 24 is mounted has a cavity structure having holes in a dielectric layer above a layer having a strip line. In this cavity, the above-mentioned strip line is a microstrip line 27. Further, the semiconductor chip 24 fixed in the cavity by brazing or an adhesive or the like and the microstrip line 27 are connected by wire bonding.

[0005] The multi-layer substrate for a multi-chip module is manufactured by laminating unfired green sheets on which electrodes are printed by thick-film printing, and simultaneously firing (Co. Fire) these laminated green sheets. I have.

[0006]

In the above-mentioned conventional multi-chip module, since the strip lines for transmitting microwaves and the microstrip lines are formed on the inner layer by thick film printing, the pattern width is ± 50 μm.
An accuracy of only about m to ± 100 μm can be obtained. This level of accuracy is insufficient for millimeter waves.

Further, when the firing temperature at the time of simultaneous firing of the green sheets is as high as 1300 ° C. or more, the material of the conductor pattern must be tungsten. However, tungsten has an electrical resistance that is about three times greater than that of gold, silver or copper, so that the loss of a transmitted signal is large.

Accordingly, an object of the present invention is to solve the above-mentioned problems, to obtain a pattern width with a pattern width accuracy that can be sufficiently used even in a millimeter wave band, and to realize a low-loss circuit. It is an object of the present invention to provide a multi-chip module substrate and a method of manufacturing the same.

[0009]

The substrate for a multi-chip module according to the present invention is formed by forming via holes in a green sheet stage and then independently firing at a high temperature after filling with a conductive paste. And a first and second dielectric substrate on which a thin-film conductor is formed on a conductive surface, and laminated between each of the first and second dielectric substrates and at least the first and second dielectric substrates. A glass ceramic layer including via holes connecting the thin film conductors of each of the body substrates, and laminating each of the first and second dielectric substrates and the glass ceramic layer and then firing them at a low temperature. .

In the method of manufacturing a substrate for a multichip module according to the present invention, the first and second dielectric substrates fired at a high temperature are each filled with a conductive paste at the green sheet stage. The step and the first
And a second step of independently baking the second dielectric substrate at a high temperature, and a third step of forming an electrode conductor on the conductor surface of each of the first and second dielectric substrates by a thin-film conductor formation technique A glass ceramic layer laminated between each of the first and second dielectric substrates and including a via hole connecting at least the electrode conductors of each of the first and second dielectric substrates. A fourth step of laminating between the first and second dielectric substrates, and a fifth step of firing each of the first and second dielectric substrates and the glass ceramic layer at a low temperature.

As described above, each of n (n is a positive integer of 2 or more) dielectric substrates, such as alumina or aluminum nitride, which has been fired at a firing temperature of 1300 ° C. or more at a high temperature, has a conductor pattern formed by a thin film conductor forming technique. Are formed, a non-fired glass ceramic layer is sandwiched between them, and then laminated at low temperature.

Thus, since the entire conductor surface of the dielectric substrate is formed using the thin-film conductor formation technique, an accuracy of ± 5 μm in pattern width is obtained, and an accuracy usable in a millimeter wave band is obtained. In addition, since low-temperature baking is performed with the glass ceramic layer interposed between the dielectric substrates, gold or the like can be used as a conductive material of the conductive surface of the dielectric substrate, so that a low-loss circuit can be realized. .

[0013]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a sectional view of one embodiment of the present invention. In the figure, 1 is a metal carrier, 2 is an alumina substrate, 3 is a low-temperature fired glass substrate, 4 is a thin film microstrip line, 5 and 6 are thin film strip lines, and 7 is connected to the thin film microstrip line 4 by gold wires. Semiconductor bare chip, 8 is a via hole, 9 is a metal cap for hermetic sealing, 10 is a thin film grounding conductor, and 11 is a gold wire for wire bonding the semiconductor bare chip 7 and the thin film microstrip line 4. is there.

FIGS. 2A to 2C are cross-sectional views showing a process for manufacturing a substrate for a multichip module according to an embodiment of the present invention. The manufacturing process of the multi-chip module substrate according to one embodiment of the present invention will be described with reference to FIGS.

The alumina substrates 2-1 and 2-2 are individually used one by one at the stage of green sheet at the holes 8a and 8a for via holes.
8b, etc., and after performing necessary processing such as filling the hole with a conductive material such as tungsten, 1300 ° C.
Simultaneous firing is performed at the above firing temperature (see FIG. 2A).

A conductor pattern (thin film strip lines 5, 6, etc.) is formed on the conductor surfaces of the fired alumina substrates 2-1 and 2-2 by a thin film conductor formation technique [FIG.
(B)].

Thereafter, if necessary, the unsintered low-temperature fired glass substrate 3 on which the via holes 8 for connecting the thin film strip lines 5 and 6 have been processed is replaced with the alumina substrates 2-1 and 2-2.
-2 and a low-temperature baking (see FIG. 2 (c)) to form a multilayer substrate having four conductive surfaces and three dielectric substrates. Thus, the conductor patterns formed inside and above and below the multilayer substrate can all be formed of thin films.

FIG. 3 is a sectional view of another embodiment of the present invention. In the drawing, another embodiment of the present invention has the same configuration as the embodiment of the present invention shown in FIG. 1 except that three alumina substrates 2 and two low-temperature fired glass substrates 3 are laminated. The same reference numerals are used for the same components.

In this case, after a conductor pattern is formed on the conductor surface of each of the three fired alumina substrates 2 by a thin-film conductor formation technique, the two unfired low-temperature fired glass substrates 3 are combined with the three alumina substrates. By laminating between each of the substrates 2 and firing at a low temperature, a multilayer substrate having six conductive surfaces and five dielectric substrates is formed.

That is, after a conductor pattern is formed on the conductor surface of each of the n alumina substrates 2 by the thin film conductor formation technique, the unfired (n-1) low-temperature fired glass substrates 3 are removed from each of the alumina substrates 2. By sintering at a low temperature after laminating between them, a multilayer substrate having a 2n-1 conductor substrate and 2n-1 dielectric substrates is formed.

In this way, the steps of drilling the via holes 8 and filling the conductive paste in the green sheet stage for each of the alumina substrates 2 fired at a high temperature,
A step of independently sintering each of them at a high temperature, a step of forming strip lines 5 and 6 on a conductor surface of each of the alumina substrates 2 by a thin film conductor forming technique, and a step of laminating between the alumina substrates 2 and at least each of the alumina substrates 2 Laminating a low-temperature fired glass substrate 3 including via holes 8 connecting the strip lines 5 and 6 between the alumina substrates 2, and firing the low-temperature fired glass substrate 3 and the alumina substrate 2 each at a low temperature. By manufacturing the multilayer substrate through the above, since all the conductor patterns of the alumina substrate 2 are formed using the thin-film conductor formation technology, the pattern width is ± 5 μm.
And an accuracy that can be used even in the millimeter-wave band.

Since the low-temperature firing glass substrate 3 is sandwiched between the alumina substrates 2, the low-temperature firing is performed.
A material with low specific resistance, such as gold, silver, or copper, can be used as the conductor material of the conductor pattern, and a circuit with lower loss than tungsten, which is a conductor material in the case of simultaneous firing at high temperatures, can be realized. it can.

In the above-described embodiment and other embodiments of the present invention, the case where the alumina substrate 2 is used as the dielectric substrate has been described. However, aluminum nitride or the like fired at a high temperature of 1300 ° C. or more is used. It is obvious that the embodiment of the present invention and other embodiments can be applied to the case where a dielectric substrate is used.

[0024]

As described above, according to the present invention, the first and second dielectric substrates to be fired at a high temperature are each subjected to the step of forming via holes and filling the conductive paste in the green sheet stage; Independently baking the first and second dielectric substrates at a high temperature, forming electrode conductors on the conductor surfaces of the first and second dielectric substrates by a thin-film conductor forming technique, A glass ceramic layer laminated between each of the second dielectric substrates and including a via hole connecting at least the electrode conductors of each of the first and second dielectric substrates is formed on each of the first and second dielectric substrates. By manufacturing a multi-layer substrate through a process of laminating between them and a process of firing each of the first and second dielectric substrates and the glass ceramic layer at a low temperature, the pattern width accuracy can be sufficiently used even in the millimeter wave band. Na pattern Can be obtained accuracy, there is an effect that it is possible to realize a low-loss circuit.

[Brief description of the drawings]

FIG. 1 is a sectional view of one embodiment of the present invention.

FIGS. 2A to 2C are cross-sectional views illustrating a process for manufacturing a multi-chip module substrate according to an embodiment of the present invention.

FIG. 3 is a sectional view of one embodiment of the present invention.

FIG. 4 is a sectional view of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Metal carrier 2 Alumina substrate 3 Low temperature firing glass substrate 4 Thin film microstrip line 5, 6 Thin film strip line 7 Semiconductor bare chip 8 Via hole 9 Metal cap for hermetic sealing 10 Thin film grounding conductor 11 Gold wire

Claims (8)

(57) [Claims] 1. A method of forming via holes and forming a thin film conductor on a conductor surface after independently performing high-temperature firing after forming via holes and filling a conductive paste in each green sheet stage. A first and a second dielectric substrate, and a via hole laminated between the first and the second dielectric substrates and connecting at least the thin film conductors of the first and the second dielectric substrates, respectively. A substrate for a multi-chip module, comprising: a glass ceramic layer containing the first and second dielectric substrates; and laminating each of the first and second dielectric substrates and the glass ceramic layer and then firing them at a low temperature. 2. The first and second dielectric substrates, respectively,
The multi-chip module substrate according to claim 1, wherein the substrate is fired at a firing temperature of 1300 ° C or higher. 3. The first and second dielectric substrates, respectively,
3. The multi-chip module substrate according to claim 1, wherein the substrate is at least one of alumina and aluminum nitride. 4. The semiconductor device according to claim 1, comprising n (n is a positive integer of 3 or more) dielectric substrates and (n-1) glass ceramic layers. The substrate for a multichip module according to any one of the above. 5. A first step of forming a via hole and filling a conductive paste in each of the first and second dielectric substrates fired at a high temperature in a green sheet stage, and the first and second dielectric substrates. A second step of independently firing each of the body substrates at a high temperature, a third step of forming electrode conductors on a conductor surface of each of the first and second dielectric substrates by a thin-film conductor formation technique, A glass ceramic layer laminated between each of the first and second dielectric substrates and including a via hole connecting at least the electrode conductors of the first and second dielectric substrates. A fourth step of laminating between the body substrates, and a fifth step of firing each of the first and second dielectric substrates and the glass ceramic layer at a low temperature.
And a method for manufacturing a substrate for a multichip module. 6. The first and second dielectric substrates, respectively,
The method according to claim 5, wherein the substrate is fired at a firing temperature of 1300 ° C or higher. 7. The first and second dielectric substrates, respectively,
The method for manufacturing a substrate for a multichip module according to claim 5, wherein the substrate is at least one of alumina and aluminum nitride. 8. The semiconductor device according to claim 5, comprising n (n is a positive integer of 3 or more) dielectric substrates and (n-1) glass ceramic layers. The substrate for a multichip module according to any one of the above.