JP3217677B2 - High frequency semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device used for high frequencies in a microwave band to a millimeter wave band, and more particularly, to transmitting a signal to a semiconductor element or a circuit component without deteriorating characteristics of a high frequency signal. The present invention relates to a semiconductor device which can be used.

[0002]

2. Description of the Related Art Conventionally, in a semiconductor device used for high frequencies in a microwave band to a millimeter wave band, as shown in FIG. 7A, a cavity formed by an insulating substrate 22 made of a dielectric and a lid 23 is used. Semiconductor device (IC) in 24
25 is hermetically sealed. Input and output of signals and the like are connected to the IC by bonding wires and the like through a high-frequency transmission line 26 such as a strip line formed on the surface of the insulating substrate 22. As another method, as shown in FIG. 7B, a high-frequency transmission line 26 is formed on the bottom surface of the insulating substrate 22, and the transmission line 26 and the IC 25 are formed.
Are connected via a through hole 27. Further, as shown in FIG. 7C, there has been proposed a device in which a transmission line 26 formed on a bottom surface of a semiconductor device is connected to a transmission line on the front surface via a side surface of the semiconductor device to transmit a signal or the like. . (Japanese Patent Application Laid-Open No. 61-168939)
issue).

[0003]

However, FIG.
As shown in FIG. 7A and FIG. 7C, when the transmission line 26 is formed on the IC mounting surface, and the transmission line 26 passes through the side wall of the lid 23, the signal line is changed to a microstrip line at the side wall passing portion. It is necessary to reduce the width of the signal line because the signal line is converted into a strip line. As a result, there is a problem in that the reflection loss and the radiation loss are easily generated in the conversion unit, so that the characteristics of the high-frequency signal are likely to deteriorate.

In addition, since the transmission line is formed on the side surface of the IC mounting surface, the size of the circuit board is difficult because the semiconductor device itself is inevitably large. FIG. 7 (b) solves this problem by using a through hole and a via hole to electrically connect to the transmission line on the bottom surface and to enable surface mounting on an external circuit board. . However, in the structure of FIG. 7B, the operating frequency of the signal to be transmitted is 10 GHz.
Above, the transmission loss in the through-hole increases rapidly, and it has been very difficult to transmit a signal in a microwave band to a millimeter wave band without characteristic deterioration.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a semiconductor device which can be used in the microwave to millimeter band region and has very little deterioration in signal characteristics, particularly a high frequency semiconductor device suitable as a surface mount type semiconductor device. Things.

[0006]

The present inventors have repeatedly studied the structure of a semiconductor device for high frequency use which can be surface-mounted without deteriorating signal characteristics. In a semiconductor device having a semiconductor element mounted inside a cavity formed by an insulating substrate and a lid, a first high-frequency transmission line electrically connected to the semiconductor element on a surface of the insulating substrate inside the cavity. And a second high-frequency transmission line formed on the bottom surface of the insulating substrate at a position facing the second high-frequency transmission line via the insulating substrate and electromagnetically coupled to the second high-frequency transmission line. A connection terminal which can be directly solder-mounted on a substrate is formed.

As an electromagnetic coupling form, a ground layer is formed in the insulating substrate, and a slot hole is formed in the ground layer, and the first high-frequency transmission line and the second high-frequency transmission line are formed. May be formed at positions facing each other via the slot hole and electromagnetically coupled, or the first may be formed on the surface of the insulating substrate inside the cavity so as to surround the terminal end of the first high-frequency transmission line. A ground layer is formed, and a second ground layer is formed so as to surround a terminal portion of the second high-frequency transmission line on a bottom surface of the insulating substrate, and a terminal of the first and second high-frequency transmission lines is formed. Parts are formed at positions facing each other via the insulating substrate and are electromagnetically coupled, and these lines are a strip line, a microstrip line, a coplanar line. , It is characterized in that at least one of the ground with a coplanar line.

[0008]

According to the present invention, a first high-frequency transmission line electrically connected to an IC element in a cavity formed by an insulating substrate made of a dielectric material and a lid, and a bottom surface of the insulating substrate. Since the transmission line can be coupled without passing through the side wall of the cover by forming the second transmission line for high frequency and the electromagnetic wave coupling at a position facing each other via the insulating substrate, the transmission line can be formed at the side wall passage portion. There is no reflection loss or radiation loss due to the signal line being converted from the microstrip line to the strip line, and there is no influence of transmission loss due to through holes and via holes. Can be transmitted with suppression.

Further, when connection to an external electric circuit board is made by a metal pin or the like, transmission loss occurs when the signal frequency becomes 10 GHz or more (specifically, S11> −10d).
B, S21 <−5 dB), a connection terminal is formed on a part of the high-frequency transmission line formed on the bottom surface, and the connection terminal is directly mounted on the external electric circuit board by soldering. There is no loss between the terminal and the high-frequency transmission line, and it can be connected to an external electric circuit.

Further, as an electromagnetic coupling structure between the high-frequency transmission lines, a ground layer is formed in the insulating substrate, and a slot hole is formed in the ground layer. A second high-frequency transmission line is formed at a position facing the second high-frequency transmission line via the slot hole and electromagnetically coupled, or a surface inside the cavity of the insulating substrate surrounds a terminal portion of the first high-frequency transmission line. The first ground layer is formed so as to surround the terminal portion of the second high-frequency transmission line on the bottom surface of the insulating substrate, and the first and second ground layers are formed.
By forming the terminal portions of the high-frequency transmission lines facing each other via the insulating substrate and performing electromagnetic coupling, signals can be transmitted without loss of signals between the transmission lines.

[0011]

FIG. 1 shows an example of a high-frequency semiconductor device according to the present invention. According to FIG. 1, a high-frequency semiconductor device 1 has a cavity 4 formed by an insulating substrate 2 made of a dielectric material and a lid 3, and a semiconductor element 5 such as an IC is mounted in the cavity 4. ing. As the dielectric material constituting the insulating substrate 2, ceramics, glass ceramics, ceramic metal composite materials, glass organic resin composite materials, and the like having a dielectric constant of 10 or less, particularly 6 or less can be used.

On the other hand, the lid 3 is desirably made of a material capable of preventing the electromagnetic wave from the cavity from leaking to the outside.
Glass ceramics and the like can be used, but an electromagnetic wave absorbing material such as carbon capable of absorbing electromagnetic waves can be dispersed in these materials, or these electromagnetic wave absorbing materials can be applied to the surface of the lid.

According to the present invention, in the above-described semiconductor device, a strip line, a microstrip line, a coplanar line,
One high-frequency transmission line of the grounded coplanar line is formed on the surface of the insulating substrate 2 in the cavity 4. FIG. 1 shows a structure when the transmission line is a microstrip line. According to FIG. 1, a ground layer 6 is formed in an insulating substrate 2, and a microstrip line 8 is formed by a strip conductor path 7 formed on the surface of the insulating substrate 2. A strip conductor path 9 is also formed on the bottom surface of the semiconductor device 1, and a microstrip line 10 is formed between the ground layers 6.

The microstrip line 8 and the microstrip line 10 are electromagnetically coupled by being formed at opposing positions via a slot hole 11 formed in the ground layer 6, thereby transmitting a lossless signal. Is performed. Note that a plurality of the slot holes 11 may be formed.

As shown in the plan view (a) and the cross-sectional view (b) of the arrangement diagram of FIG. 2, the strip conductor paths 7 and 9 through the slot hole 11 The slot hole 11 is desirably formed at a confronting position overlapping at a wavelength of / 2, and the shape of the slot hole 11 is a rectangular hole having a long side and a short side. The width can be specified. Therefore, the long side of the slot hole is desirably set to a length corresponding to １ ／ wavelength of the signal frequency, and the short side of the slot hole is set to a length corresponding to １ ／ wavelength to 1/50 wavelength, whereby the bandwidth becomes Can be controlled to 3 GHz to 10 GHz.

In this arrangement, the end portions 12 and 13 of the strip conductor paths 7 and 9 have multi-step or fan-shaped conductor path widths as shown in FIG. It is desirable to adopt a shape that is expanded to a width. In order to further improve the characteristics of the high-frequency signal at the ends 12 and 13 and to prevent leakage waves from the ends of the transmission line and the vicinity of the slot holes, as shown in FIG.
A second earth layer 14 is arranged in a semicircular shape around the slot hole 11 and around the end portions 12 and 13 of the conductor paths 7 and 9.
It is desirable that the ground layer 14 and the ground layer 6 in the insulating substrate 2 are formed by a plurality of via holes 15 so as to surround the ends 12, 13 or the periphery of the slot hole 11. At this time, the interval between the via holes 15 is 1/1 of the signal wavelength.
4 or less.

A connection terminal 16 is formed on a part of the strip conductor path 9 formed on the bottom surface of the semiconductor device 1. For example, the solder ball 1 is connected to the connection terminal 16.
7 is attached by solder or the like.
7 and can be connected to an external electric circuit board by soldering. In addition, as for the connection method, a connection method using silver brazing or gold bumps other than the above may be used.

The IC element 5 has a strip conductor path 7
Can be connected without transmission loss by being directly formed on the substrate by soldering or the like.
The method of connecting to is not limited to this,
For example, the connection can be made by gold ribbon or several wire bondings, or by a conductor plate in which a conductor such as Cu is formed on a substrate such as polyimide.

FIG. 5 shows a schematic layout of a coplanar line as a structure for electromagnetically coupling a transmission line in the semiconductor device of the present invention.
1A is a schematic view of a semiconductor device, and FIG. 1B is a plan view of a coupling structure between transmission lines. According to FIG. 5, a conductor path 18 connected to the IC element 5 is formed on the surface of the insulating substrate 2 in the cavity 4, and a position where the conductor path 19 faces the bottom surface of the insulating substrate 2 via the insulating substrate 2. Is formed. The ends of the conductor paths 18 and 19 are formed such that the line widths of the end parts are small, and the narrow portions are opposed to each other so that the conductor paths 19 or 19 overlap. I have. The length of the overlapping portion is desirably a length corresponding to １ ／ wavelength to 波長 wavelength of the signal frequency.

A first ground layer 20 is formed around the end of each conductor path 18. A second ground layer 21 is also formed around the end of the conductor path 19 formed on the bottom surface.

According to the above arrangement, the conductor path 18 and the second ground layer 2 are connected between the conductor path 18 and the first ground layer 20.
A coplanar line is formed between the two coplanar lines, and these coplanar lines can be electromagnetically coupled between the two coplanar lines by opposing the positions via the insulating substrate 2 as described above.

In this configuration, the conductor path 1
By forming the connection terminal 16 in a part of the connector 9, it is possible to connect to an external electric circuit without signal transmission loss.

In the high-frequency semiconductor device of the present invention configured as described above, the semiconductor device of FIG. 1 has a dielectric constant of 5.5 and a dielectric loss of 15.0 × 10 ⁻⁴ (measuring frequency 12 GHz) as an example. A semiconductor device was manufactured using a body material, a dielectric material having a dielectric constant of 8.9 and a dielectric loss of 9.0 × 10 ⁻⁴ (measurement frequency 10.5 GHz), and copper or tungsten as a conductor. Transmission characteristics at the input section of the semiconductor device were measured by a network analyzer. FIG. 6 shows the result. From FIG. 6, the semiconductor device has a center frequency of 20 GHz, a bandwidth of 5.5 GHz, and S11: -2.
Characteristics of 0 to -35 dB and S21: -0.8 dB or more are obtained, and almost no deterioration of the characteristics of the high-frequency signal is observed around 20 GHz.

Next, in the semiconductor device having the conventional structure shown in FIG. 7B, the dielectric constant is 5.5 and the dielectric loss is 45.0 ×
A semiconductor device in which a dielectric material of 10 ^-4 (measurement frequency: 60 GHz) and a transmission line formed on the bottom surface are connected by a via hole made of a copper conductor having a diameter of 100 μm was similarly measured by a network analyzer, and FIG. Figure 8 shows the results. FIG.
From the result of the above, when the transmission line is connected by the via hole,
When the frequency is 20 GHz or more, S11: -20 dB or more, S
21: -50 dB or less, indicating that it is impossible to transmit a high-frequency signal to the semiconductor element.

[0025]

As described in detail above, in the high-frequency semiconductor device of the present invention, the transmission lines face each other via the slot hole formed in the ground layer, or the terminal of the first high-frequency transmission line is closed. A first ground layer is formed so as to surround the first ground layer, and a second ground layer is formed so as to surround the end of the second high-frequency transmission line on the bottom surface of the insulating substrate. Since the end portions of the high-frequency transmission line are electromagnetically coupled by being opposed to each other via the insulating substrate, reflection loss and radiation loss do not occur, and transmission loss due to through holes and the like does not affect the transmission characteristics. Since high-frequency signals with little deterioration can be input to and output from the semiconductor element, and the semiconductor device can be directly surface-mounted on an external electric circuit board by soldering or the like,
The size of the circuit board can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an example of a high-frequency semiconductor device according to the present invention.

2A and 2B are layout diagrams of a strip conductor path in FIG. 1, wherein FIG. 2A is a plan view and FIG. 2B is a cross-sectional view.

FIG. 3 is a diagram for explaining a preferred shape of an end of a transmission line in the semiconductor device of the present invention.

FIG. 4 is a view for explaining another preferred shape of the end of the transmission line in the semiconductor device of the present invention.

5A and 5B show another example of the high-frequency semiconductor device of the present invention, in which FIG. 5A is a schematic layout diagram, and FIG. 5B is a plan view for explaining a coupling structure of a transmission line.

FIG. 6 is a diagram showing transmission characteristics of the semiconductor device of the present invention shown in FIG. 1;

FIGS. 7A to 7C are views for explaining the structure of a conventional high-frequency semiconductor device, and FIGS. 7A to 7C are schematic views for explaining an example thereof.

FIG. 8 is a diagram illustrating transmission characteristics of the semiconductor device having the structure of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 High frequency semiconductor device 2 Insulating substrate 3 Lid 4 Cavity 5 Semiconductor element 6 Ground layer 7, 9 Strip conductor path 8, 10 Microstrip line 11 Slot hole 12, 13 End part 14 Second ground layer 15 Via hole 16 Connection terminal 17 Solder ball

Claims (3)

(57) [Claims] In a semiconductor device in which a semiconductor element is mounted inside a cavity formed by an insulating substrate made of a dielectric material and a lid, a surface of the insulating substrate inside the cavity is electrically connected to the semiconductor element. A first high-frequency transmission line connected thereto, and a second high-frequency transmission line formed on the bottom surface of the insulating substrate. A ground layer is formed in the insulating substrate, and a slot hole is formed in the ground layer. And forming the first high-frequency transmission line and the second high-frequency transmission line at positions facing each other via the slot and electromagnetically coupling the first high-frequency transmission line and the second high-frequency transmission line. A high-frequency semiconductor device characterized in that a connection terminal that can be directly solder-mounted on an external circuit board is formed in a portion. 2. A semiconductor device in which a semiconductor element is mounted inside a cavity formed by an insulating substrate made of a dielectric material and a lid, wherein the surface of the insulating substrate inside the cavity is electrically connected to the semiconductor element. A first high-frequency transmission line connected thereto, a second high-frequency transmission line formed on the bottom surface of the insulating substrate, and a second high-frequency transmission line formed on the surface of the insulating substrate so as to surround a terminal end of the first high-frequency transmission line. A first ground layer, a second ground layer is formed on a bottom surface of the insulating substrate so as to surround a terminal end of the second high-frequency transmission line, and the first and second high-frequency transmission lines are formed. A high-frequency semiconductor device characterized in that terminal portions of the semiconductor device are formed at positions facing each other via the insulating substrate and are electromagnetically coupled. 3. The transmission line according to claim 1, wherein the first transmission line and the second transmission line are at least one of a strip line, a microstrip line, a coplanar line, and a grounded coplanar line. The high-frequency semiconductor device according to claim 1.