JP3398282B2 - High frequency semiconductor device - Google Patents

Description

Description: 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 in particular, without deteriorating the characteristics of a high frequency signal. The present invention relates to a semiconductor device capable of transmitting a signal to a semiconductor element or a circuit component, and further relates to a high-frequency semiconductor device having a built-in filter circuit capable of transmitting only a signal of a specific frequency. 2. Description of the Related Art Conventionally, in a semiconductor device for handling microwave or millimeter wave signals, as shown in FIG. 7A, a cavity 22 formed by an insulating substrate 20 made of a dielectric and a lid 21 is used. A semiconductor element (IC) 23 is mounted on the device and hermetically sealed. The input and output of signals and the like are performed on the insulating substrate 2.
A high-frequency transmission line 24, such as a strip line, is formed on the surface 0, and the transmission line 24 and the IC 23 are connected by wire bonding, a ribbon, or the like. As another method, as shown in FIG. 7 (b), a high-frequency transmission line 24 is formed on the bottom surface of the insulating substrate 20, and the transmission line 24 and the IC 23 are connected through a through hole 25. I have. Further, as shown in FIG. 7C, there has been proposed a device in which a transmission line 24 formed on the 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 Laid-Open No. 61-16893)
No. 9). Recently, an input filter or an internal circuit (MMIC) for protecting the internal circuit (MMIC) has been used.
In such a case, an output filter for blocking noise generated from the semiconductor device is required. In such a case, a band-pass filter is separately provided outside the semiconductor device, or FIGS. 7A to 7C are used. It has also been proposed to form a part of the transmission line 24 outside the cavity of the insulating substrate 20 of the semiconductor device, for example, in the side wall (Japanese Patent Laid-Open No. 7-273273).
issue). [0004] However, FIG.
As shown in (a) and (c), when the transmission line 24 is formed on the IC mounting surface, and the transmission line 24 passes through the lid 21, the signal line is changed from the microstrip line to the strip line at the side wall passing portion. Therefore, it is necessary to reduce the width of the signal line. As a result, reflection loss and radiation loss are apt to occur in the conversion unit, so that there is a problem 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 semiconductor device itself is inevitably large, so that it is difficult to reduce the size of the circuit board. [0005] FIG. 7 (b) solves this problem by using a through-hole 25 to electrically connect to a transmission line on the bottom surface, thereby enabling surface mounting on an external circuit board. However, in the structure of FIG. 7B, when the operating frequency of the signal to be transmitted becomes 10 GHz or more, the through hole 2
5, the transmission loss in the range from microwave band to millimeter wave band is difficult to transmit without characteristic deterioration. Further, in a semiconductor device having a function of passing only a specific frequency, a device provided with a filter outside of FIG. 7A cannot contribute to downsizing of the whole device, and furthermore, a band-pass filter circuit Even in a device in which the transmission line is formed on a part of the transmission line, the area of the transmission line formation surface becomes large, and especially when the device is formed on the side wall of the insulating substrate, the side wall of the insulating substrate is very small, so it is difficult to print the line. In addition, there is a danger that the resonance lines are short-circuited. Accordingly, the present invention provides a high-frequency semiconductor device that can be used in the microwave to millimeter-wave band and has very little deterioration in signal characteristics. It is an object to provide a semiconductor device for use. Means for Solving the Problems The present inventors have developed a semiconductor device for high frequency use such as microwaves and millimeter waves.
As a result of repeated studies on the structure of a semiconductor device having a filter capable of passing only a signal of a specific frequency without deterioration of signal characteristics, the structure was formed by an insulating substrate and a lid in which a plurality of dielectric materials were laminated. A first high-frequency transmission line electrically connected to the semiconductor element is formed on a surface of the insulating substrate inside the cavity, the semiconductor device having a semiconductor element mounted inside the cavity. A second high-frequency transmission line is formed on the bottom surface, and a filter circuit for passing only a signal of a specific frequency is provided in the insulating substrate, wherein the first high-frequency transmission line and the second high-frequency transmission line are provided. Has been found to be able to transmit only a specific signal without loss of a transmission signal by electromagnetically coupling through the filter circuit. Further, in the present invention, in addition to the above configuration, by disposing the filter circuit between the high dielectric constant dielectric layers, the filter circuit itself can be reduced in size and can be built in a high-frequency semiconductor device. ,
In addition, it has been found that the transmission characteristics of a high-frequency signal can be improved. That is, the high-frequency semiconductor device of the present invention has an insulating substrate formed by laminating a plurality of dielectric layers, a semiconductor element mounted in a cavity formed by a lid, and the insulating substrate in the cavity. A first high-frequency transmission line electrically connected to the semiconductor element, a second high-frequency transmission line formed on the bottom surface of the insulating substrate, and only a signal of a specific frequency within the insulating substrate. comprising a filter circuit for passing, a semiconductor device which is electromagnetically coupled with said first high frequency transmission line and said second high-frequency transmission line through said filter circuit, said Fi
The filter circuit is provided with a slot hole formed in the first ground layer.
Electromagnetically coupled to the first high-frequency transmission line via
Through a slot hole formed in the second ground layer.
The first and second high-frequency transmission lines are electromagnetically coupled to a high-frequency transmission line, the first and second high-frequency transmission lines are formed on a surface of a low-k dielectric layer, and the filter circuit is disposed between the high-k dielectric layers. It is characterized by having. [0010] According to the above configuration of the present invention, the IC element is electrically connected to the IC element inside the cavity formed by the insulating substrate and the lid on which a plurality of dielectric materials having different dielectric constants are laminated. The first transmission line for high frequency and the second transmission line for high frequency on the bottom surface of the insulating substrate are formed at positions facing each other via the filter circuit and are electromagnetically coupled to each other so that the transmission line is formed on the cover. Since coupling can be performed without passing through the side wall, there is no reflection loss and radiation loss due to conversion of the signal line from the microstrip line to the strip line at the side wall passing portion, and transmission loss due to through holes and via holes. Therefore, the transmission loss of the high-frequency signal can be suppressed, and the signal of the required frequency can be transmitted through. Further, the first and second high-frequency transmission lines are formed on the surface of a low dielectric constant dielectric layer, and the filter circuit is disposed between insulating layers made of a high dielectric constant dielectric material. The size of the filter circuit can be further reduced as compared with the case where the filter circuit is formed from the same dielectric material, and the transmission characteristic of a high-frequency signal can be improved. 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 in which a plurality of dielectric layers are stacked and a lid 3.
Inside, a semiconductor element 5 such as an IC is mounted. As the dielectric material constituting the insulating substrate 2, glass ceramics, a ceramic metal composite material, a glass organic resin composite material, or the like is suitably used. On the other hand, the lid 3 is preferably 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 it is also possible to disperse a small amount of an electromagnetic wave absorbing substance such as carbon capable of absorbing electromagnetic waves in these materials, or to apply these electromagnetic wave absorbing substances to the surface of the lid. Further, in order to prevent leakage of electromagnetic waves, Au-S when sealing with the lid 3 is used.
It is desirable that the sealing portion of n, Au-Si or the like be connected to a through hole in the wall, a metallized layer outside the wall, or the like so as to have the same potential. According to the present invention, in the above-described semiconductor device, one type of high-frequency transmission line selected from a microstrip line, a strip line, and a coplanar line with ground is used as a line for transmitting a signal to the semiconductor element 5. Are formed on the surface of the insulating substrate in the insulating substrate in the cavity 4. According to the semiconductor device of FIG. 1, the transmission line is formed as a microstrip line. According to FIG. 1, the insulating substrate is constituted by a plurality of dielectric layers. A strip line 6 is formed on the surface of the insulating substrate 2 in the cavity 4, and a strip line 7 is formed on the bottom surface of the insulating substrate 2. Further, a filter circuit 8 is formed in the insulating substrate 2. The end of the strip line 6 is opposed to the end of the filter circuit 8 with a slot hole 10 formed in the ground layer 9 made of a conductor layer interposed therebetween. Be combined. On the other hand, the end of the strip line 7 is opposed to the end of the filter circuit 8 with a slot hole 12 formed in the ground layer 11 made of a conductor layer interposed therebetween. Be combined. The strip line 6 forms the microstrip line 13 together with the ground layer 9, and the strip line 7 forms the microstrip line 1 together with the ground layer 11.
4 is formed. As is apparent from the perspective view of FIG. 2, the strip line 6 formed through the slot 10 and the end of the filter circuit 8 sandwich the slot 10 formed in the ground layer 9. It is preferable that the ends of the respective lines are formed so as to overlap each other at a length corresponding to about 波長 wavelength of a required transmission signal frequency in a plane.
Is a rectangular hole having a long side and a short side, and the shape of the hole can specify the used frequency and the bandwidth of the frequency. Therefore, the long side of the slot hole is desirably set to a length corresponding to １ ／ wavelength of the transmission signal frequency, and the short side of the slot hole is set to １ ／ of the length corresponding to １ ／ wavelength.
When set to a length corresponding to 0 wavelength, the bandwidth is 3 GHz to 20 GHz.
GHz can be controlled. In order to further improve the signal transmission characteristics, it is desirable to reduce the characteristic impedance of the slot hole. Therefore, it is particularly desirable that the short side of the slot hole is not more than 1/10 wavelength equivalent length. In the semiconductor device of FIG. 1, as shown in FIG. 3, a filter circuit 8 includes conductor paths 15 of the same shape having a length corresponding to a half wavelength of the transmission signal frequency arranged at equal intervals in multiple stages on the same plane. It is formed by the arranged planar strip resonance lines. The strip resonance line is formed with an earth band 16 around the filter circuit 8 so that electromagnetic waves do not leak around the strip resonance line, and the earth band 16 is electrically connected to the earth layers 9 and 11 via holes 17. It is connected. The structure of the filter circuit 8 is as follows.
The conductor paths 18 are not limited to those formed on the same plane as shown in FIG. 1, and may be formed in multiple stages on a plurality of planes as shown in FIG. 4, for example. In this case, in coupling with the high-frequency transmission lines 6 and 7 through the slot hole 10 or the slot hole 12 at the end of the conductor path 18, the distance X ₁ between the conductor path 18 A and the ground layer 9 is set to be equal to the ground layer 11. by narrower than the interval X _2, as compared to FIG. 1 and the interval X ₁ and spacing X ₂ are the same, is more efficient electromagnetically coupling the conductor 18A and the transmission line 6, the specific frequency of the signal Can be improved. Further, according to FIG.
The relationship between 8B and the transmission line 7 is the same as above. Further, according to the high frequency semiconductor device of the present invention, the dielectric layers 2A and 2C on which the high frequency transmission lines 6 and 7 are formed are made of a dielectric material having a low dielectric constant for the purpose of improving high frequency transmission characteristics. The filter circuit 8 is made smaller from a semiconductor material by forming the dielectric layer 2B on which the filter circuit 8 is disposed from a dielectric material having a higher dielectric constant than the dielectric layers 2A and 2C. It can be stored in the device. In this case, the dielectric layers 2A, 2C
May be the same dielectric material. Specifically, the dielectric constant is 7 or less, particularly 6 or less, and the dielectric layer 2B desirably has a dielectric constant of 9 or more, particularly 12 or more. When the semiconductor device 1 is mounted on an external circuit board (not shown), a connection terminal is formed on a part of the strip line 7 formed on the bottom surface, and the connection terminal is formed through the connection terminal. It is common to connect to an external electric circuit board by soldering. However, in this method, there is a problem that impedance mismatch occurs at a connection terminal portion and reflection loss easily occurs. Therefore, it is desirable that a part of the strip line 7 formed on the bottom surface of the semiconductor device 1 be directly connected to the conductor circuit on the surface of the external circuit board by using solder or the like.
As still another connection method to the external circuit board, since impedance mismatch may occur even at the solder connection part, the strip line 7 and the transmission line on the external circuit board are mounted by overlapping and contacting each other, It is desirable to fix the solder at a portion other than the line. The IC element 5 can be connected without any transmission loss by being directly mounted on the strip line 6 by means of solder, gold bumps or the like, but the connection between the strip line 6 and the IC element 5 can be achieved. The method is not limited to this. For example, connection is made by gold ribbon or several wire bonding, or C
The connection can also be made by a conductor plate or the like on which a conductor such as u is formed. In the high-frequency semiconductor device of FIG. 1 of the present invention, the dielectric layers 2A and 2C have a dielectric constant of 5.6 and a dielectric loss of 1
The dielectric layer 2B is made of a dielectric material of 5.0 × 10 ⁻⁴ (measuring frequency 13.2 GHz) made of glass ceramics, and has a dielectric constant of 14.6 and a dielectric loss of 3.5 × 10 ⁻⁴ (measuring frequency 9 (2 GHz) made of a dielectric material made of glass ceramics, and a semiconductor device was manufactured using copper as a conductor for each line. For comparison, a semiconductor device was manufactured using only a dielectric material having a dielectric constant of 5.6 and a dielectric loss of 15.0 × 10 ⁻⁴ (measuring frequency 13.2 GHz). Transmission characteristics at the input / output unit of the semiconductor device were measured by a network analyzer. 5 (a) and 5 (b) show the results.
According to the results of FIG. 5, it is understood that the characteristics of S21 are improved. When the filter circuit 8 has the structure shown in FIG. 4, the dielectric layers 2A and 2C and the dielectric layer 2B are composed of two kinds of dielectric layers in the same manner as described above. the dielectric layer thickness X ₁ of the ground layer 9 side of the conductor paths 18A as 200 [mu] m of, 200 [mu] m the dielectric layer thickness X ₂ of the ground layer 11 side, 250 [mu] m,
FIG. 6 shows the change of the transmission characteristics at the time of changing to 300 μm and 400 μm. According to the results of FIG. 6, the transmission characteristics are improved as the thickness X ₂ of the dielectric layer on the ground layer 11 side is increased, and it is particularly preferable that X ₂ / X ₁ is 1.5 or more, especially 2 or more. Understand. As described above in detail, according to the high frequency semiconductor device of the present invention, the dielectric layer has a filter circuit,
In a semiconductor device in which this filter circuit is electromagnetically coupled with a high-frequency transmission line formed on the front and back surfaces of the insulating substrate, the dielectric layer of the filter circuit forming portion has a higher dielectric constant than other dielectric layers, The size of the filter circuit itself can be reduced, and the transmission characteristics can be improved. Thus, not only can a signal of a specific frequency be input / output, the size of the semiconductor device can be reduced, and excellent filter characteristics can be realized.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic layout diagram showing an example of a high-frequency semiconductor device according to the present invention. FIG. 2 is a perspective view for explaining a structure of electromagnetic coupling in the high-frequency semiconductor device of FIG. 1; FIG. 3 is a schematic diagram for explaining a structure of a filter circuit in the high-frequency semiconductor device of FIG. 1; FIG. 4 is a schematic diagram for explaining another structure of the filter circuit. 5A and 5B are diagrams showing transmission characteristics of the semiconductor device of FIG. 1, wherein FIG. 5A is the present invention and FIG. 5B is a comparative example. FIG. 6 shows X ₁ , X in the filter circuit in FIG.
FIG. 6 is a diagram showing transmission characteristics when ₂ is changed. FIG. 7 is a schematic layout diagram for explaining the structure of a conventional high-frequency semiconductor device. DESCRIPTION OF SYMBOLS 1 High frequency semiconductor device 2 Insulating substrates 2A, 2B, 2C Dielectric layer 3 Lid 4 Cavity 5 Semiconductor element 6, 7 Strip line 8 Filter circuit 9, 11 Ground layer 10, 12 Slot hole 13, 14 Microstrip line 15, 18, 18A, 18B Conductor path 16 Earth band 17 Via hole

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 23/12-23/15

Claims (1)

(57) Claims 1. An insulating substrate formed by laminating a plurality of dielectric layers, and a semiconductor element mounted in a cavity formed by a lid, wherein the insulating substrate in the cavity is provided. A first high-frequency transmission line electrically connected to the semiconductor element, a second high-frequency transmission line formed on the bottom surface of the insulating substrate, and only a signal of a specific frequency within the insulating substrate. A filter circuit for passing the first
A high-frequency transmission line and the second high-frequency transmission line are electromagnetically coupled via the filter circuit , wherein the filter circuit is formed on a first ground layer.
And the first high-frequency transmission line through the slotted hole.
Slot electromagnetically coupled and formed in the second ground layer
Electromagnetically coupled to the second high-frequency transmission line through the hole.
Ri, said first and second high-frequency transmission line is formed in the low k dielectric layer surface, wherein the filter circuit, high frequency semiconductor, characterized in that disposed in the high-k dielectric layers apparatus.