JP2001035967A - High-frequency semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor device, which can suppress the ripple of the impedance of wiring after mounting of a high frequency semiconductor element, and also can remove the reflection of a high frequency signal due to change in line width and further enables a defective element after its mounting to be replaced easily, having a mounting structure improved in both the aspect of high frequency property and the aspect of manufacture process. SOLUTION: This high-frequency semiconductor device possesses a wiring board 21, which has a recess 22a at the topside of a dielectric substrate 22 and in which a line conductor 24 is made around the opening and earth conductors 23 and 23a are made at the lowerside and at the bottom of the recess 22a, a wiring board 25 for mounting which is attached to cover the opening of the recess 22a and whose connecting electrode 28a is abutted and connected to the line conductor 24, and a high-frequency semiconductor element 31 which is connected to a mounted electrode 30a. In this case, the wiring board 25 for mounting comprises a main dielectric layer 26, which is larger than the dimension of the opening of the recess 22a and moreover whose relative dielectric constant is larger than that of dielectric substrate 22, a sub dielectric layer 27 whose relative dielectric constant is smaller than that of the main dielectric layer 26, a line conductor 28 for mounting which is made between the main dielectric layer 26 and the sub dielectric layer 27 from a connecting electrode 28a, and a through-conductor 30 which connects the line conductor 28 for mounting to the mounted electrode 30a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-frequency semiconductor device used for communication equipment or sensors using microwaves or millimeter waves, and more particularly to a high-frequency semiconductor device having an improved mounting structure of a high-frequency semiconductor element.

[0002]

2. Description of the Related Art Conventionally, in a high-frequency electronic circuit module mainly including a high-frequency semiconductor element operating in a microwave or millimeter-wave band, the high-frequency semiconductor element is mounted on a high-frequency semiconductor mounting board using a dielectric substrate. Further, the high-frequency semiconductor mounting board is housed in a metal chassis together with other circuit boards and the like.

A conventional high-frequency semiconductor device in which a high-frequency semiconductor device is mounted on such a high-frequency semiconductor mounting substrate is, for example, a ground conductor 3 on a lower surface as shown in a sectional view of a main part in FIG. The concave portion 2a and the concave portion 2
a wiring board 1 composed of a dielectric substrate 2 having a line conductor 4 formed around the periphery of the opening a;
And a wiring conductor 9 formed on the lower surface of the high-frequency semiconductor element 7 by flip-chip mounting the high-frequency semiconductor element 7 on the mounting wiring board 5 with the conductive bumps 10 and the mounting wiring board. 5 and a grounding conductor 8 formed on the rear surface of the high-frequency semiconductor element 7 and the wiring board 1 or the mounting wiring board 5 on which the high-frequency semiconductor element 7 is mounted. And a die mounting land pattern (not shown) as an electrode for ground connection formed by a brazing material (not shown) such as gold tin or the like. A line conductor 4 formed around the opening of the concave portion 2a of the wiring board 1 as an external electric circuit is connected to a gold wire.
Mainly, they are electrically connected by wire bonding using 11 or the like.

In FIG. 8, reference numeral 12 denotes a through conductor for grounding for electrically connecting the lower surface of the mounting wiring board 5 to the ground conductor 3 on the lower surface of the wiring board 1 via the bottom surface of the concave portion 2a.
Reference numeral 13 denotes a metal shield used in the high-frequency semiconductor device.

However, as the operating frequency of the high-frequency semiconductor element 7 increases, the bonding wire for connection
In recent years, since the influence of the parasitic characteristics due to 11 becomes remarkable, in recent years, the mounting line conductor 6 of the mounting wiring board 5 and the line conductor 4 of the wiring board 1 are also electrically and mechanically connected using the conductor bumps. It has been proposed to adopt flip-chip mounting to suppress such parasitic characteristics.

[0006] Usually, such flip chip mounting is
The main surfaces on which the input / output electrodes of the high-frequency semiconductor element and the high-frequency semiconductor mounting board on which the high-frequency semiconductor element is mounted are opposed to each other, and the electrode on the high-frequency semiconductor element and the electrode on the mounting board corresponding to this electrode are connected. It has a structure to be electrically connected by conductor bumps.

[0007]

However, the high-frequency semiconductor element employs a planar transmission line using a line conductor such as a microstrip line for the wiring structure on its surface, and its impedance design is optimal for a single semiconductor element. However, when flip-chip mounting is performed, the dielectric of the mounting substrate having a relatively high relative dielectric constant is arranged below the wiring portion on the surface of the semiconductor element, so that the impedance of the wiring is reduced. Has a value different from the design value, and a desired circuit operation cannot be guaranteed.

In a region where the semiconductor element and the mounting board overlap each other, the dielectric of the semiconductor element and the dielectric of the mounting board are arranged above and below the line conductor.
In order to match the impedance, it is necessary to reduce the line width of the line conductor, but such a change in the line width corresponds to a discontinuous point that causes reflection of a high-frequency signal.
Particularly in the high frequency band, there is a problem that the signal transmission characteristics are deteriorated.

Flip-chip mounting has originally developed as a technique for reducing the mounting area and improving the exchangeability of defective elements in mounting high-speed digital circuit elements.
When performing flip-chip mounting of high-frequency semiconductor elements with bare chips, it is difficult to replace defective elements after mounting from the viewpoint of mechanical strength, etc., so it is possible to increase the rate of non-defective products when assembling multi-chip modules. There was also a problem that it was difficult.

The present invention has been devised in view of the above-mentioned problems of the prior art, and has as its object to suppress a change in the impedance of a wiring after mounting a high-frequency semiconductor element and to realize a high-frequency signal due to a change in a line width. An object of the present invention is to provide a high-frequency semiconductor device having an improved mounting structure in terms of high-frequency characteristics and manufacturing process, which can eliminate the reflection of light and can easily replace defective elements after mounting.

[0011]

The high-frequency semiconductor device of the present invention has a concave portion for accommodating a high-frequency semiconductor element on an upper surface of a dielectric substrate. A wiring board having a ground conductor formed on the bottom surface of the recess, and a wiring electrode mounted on the wiring board so as to cover an opening of the recess, and a connection electrode formed on a peripheral portion of the lower surface is in contact with the line conductor; A high-frequency semiconductor device comprising: a mounting wiring board; and a high-frequency semiconductor element electrically connected to a mounting electrode formed on a lower surface of the mounting wiring board via a conductive bump, wherein the mounting wiring board is provided. Is larger than the opening size of the concave portion, and a main dielectric layer having a larger relative dielectric constant than the dielectric substrate, and smaller than the opening size laminated on the lower surface thereof, and has a relative dielectric constant larger than the main dielectric layer. small A sub-dielectric layer, a mounting line conductor formed from the connection electrode formed around the lower surface of the main dielectric layer to the main dielectric layer and the sub-dielectric layer, and a mounting line conductor And a through conductor electrically connected to the mounting electrode formed on the lower surface of the sub-dielectric layer.

According to the high-frequency semiconductor device of the present invention, a wiring substrate having a recess for accommodating a high-frequency semiconductor element, having a line conductor formed around an opening and a ground conductor formed on a bottom surface, is flipped to a wiring substrate for mounting. The chip-mounted high-frequency semiconductor element is electrically connected to the line conductor of the wiring board via the mounting line conductor of the mounting wiring board, and is mounted so as to be accommodated in the concave portion. Is composed of a main dielectric layer having a large relative dielectric constant attached to the opening of the concave portion and a sub-dielectric layer having a small relative dielectric constant laminated on the high-frequency semiconductor element side thereof. Alternatively, since a dielectric having a lower dielectric constant than that of a conventional mounting substrate can be arranged above the wiring portion formed on the surface, a high-frequency semiconductor element when flip-chip mounting is performed. , The amount of deviation of the impedance from the original impedance design of the wiring can be suppressed, and a dielectric having a relatively high relative dielectric constant is arranged below the wiring portion of the high-frequency semiconductor element as in the related art. Therefore, compared to the case where the impedance of the wiring becomes different from the design value and the desired circuit operation is not guaranteed,
The original design value of the characteristics of the high-frequency semiconductor element can be guaranteed.

The line width of the line conductor of the inner layer wiring in the mounting wiring board is determined by the thickness of the main dielectric layer and the sub-dielectric layer and the grounding of the bottom surface of the concave portion formed on the wiring board from the surface of the sub-dielectric layer. By using the distance to the conductor,
This increases the degree of freedom in impedance design.
As a result, the amount of change in the line width of the line conductor can be kept extremely small, and a portion corresponding to a discontinuous point that causes reflection of a high-frequency signal can be eliminated, so that signal transmission characteristics do not deteriorate. Therefore, a high-frequency semiconductor device having good transmission characteristics for high-frequency signals is obtained.

Further, since the high-frequency semiconductor element is mounted on the mounting wiring board having high mechanical strength and the mounting wiring board is mounted on the wiring board, even if a defective element occurs after mounting, the mounting is performed. Since the wiring board only needs to be replaced, the overall non-defective rate is improved when a multi-chip module is configured, compared to a conventional mounting structure in which it is difficult to replace defective elements after mounting by bare chip mounting. Can be easily achieved.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A high-frequency semiconductor device according to the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing an example of an embodiment of a high-frequency semiconductor device according to the present invention, and FIG. 2 is an enlarged sectional view of a main part thereof. 3 is a cross-sectional view of a main part taken along line AA 'in FIG. 2, FIG. 4 is a cross-sectional view of a main part taken along line BB' in FIG.
FIG. 3 is a sectional view of a principal part taken along line CC ′ of FIG. 2.

In these figures, reference numeral 21 denotes a wiring board, which has a concave portion 22a for accommodating a high-frequency semiconductor element on an upper surface of a dielectric substrate 22, and a line conductor 24 around an opening of the concave portion 22a.
Are formed, and ground conductors 23 and 23a are formed on the lower surface and the bottom surface of the concave portion 22a.

Reference numeral 25 denotes a mounting wiring board, which is a main dielectric layer 26 having a larger relative opening than the opening size of the concave portion 22a of the wiring substrate 21 and a relative dielectric constant larger than that of the dielectric substrate 22, and a concave portion 22a laminated on the lower surface thereof. And a sub-dielectric layer 27 having a smaller relative dielectric constant than the main dielectric layer 26 and a connection electrode 28a formed around the lower surface of the main dielectric layer 26. Mounting line conductor formed between body layers 27
28, and a through conductor 30 for electrically connecting the mounting line conductor 28 to a mounting electrode 30a formed on the lower surface of the sub-dielectric layer 27, so as to cover the opening of the concave portion 22a on the wiring board 21. A connection electrode 28 a attached and formed around the lower surface of the main dielectric layer 26 is connected to the line conductor 24.

Reference numeral 31 denotes a high-frequency semiconductor element, which is a mounting electrode 30a formed on the lower surface of the sub-dielectric layer 27 of the mounting wiring board 25.
A terminal electrode (not shown) is electrically connected to the terminal via a conductive bump. Reference numeral 32 denotes a wiring conductor serving as a wiring portion formed on the upper surface of the high-frequency semiconductor element 31, and reference numeral 33 denotes an element ground conductor formed on the lower surface of the high-frequency semiconductor element 31.

Reference numeral 29 denotes a main dielectric layer of the mounting wiring board 25.
The mounting plane conductor 28 is formed on the same plane as the mounting line conductor 28 between the sub-dielectric layer 26 and the sub-dielectric layer 27.This mounting plane conductor 29 and the mounting line conductor 28 form a coplanar line. Is composed. In addition, the same plane ground conductor 29 for mounting is electrically connected to the same plane ground conductor (not shown) formed on the same plane as the line conductor 24 on the upper surface of the wiring board 21 so that A high-frequency circuit connected to the mounting wiring board 25 by a coplanar line is configured.

Reference numeral 35 denotes a ground conductor 23 on the lower surface of the wiring board 21 and a concave portion.
This is a through conductor for grounding for electrically connecting to the grounding conductor 23a on the bottom surface 22a. 36 is a wiring board 21 so as to cover the mounting wiring board 25 mounted on the wiring board 21 as necessary.
, Which is a metal shield here. Reference numeral 37 denotes, for example, solder for electrically connecting the line conductor 24 and the connection electrode 28a. Reference numeral 38 denotes an air layer existing in the recess 22a or between the wiring board 21 and the mounting wiring board 25 and the lid 36.

With such a structure, the high-frequency semiconductor device of the present invention has a high-frequency semiconductor element having a terminal electrode on the upper surface.
A mounting electrode 30a for flip-chip mounting corresponding to the terminal electrode of the high-frequency semiconductor element 31, and a connection electrode for input / output with the wiring board 21 as an external electric circuit
A mounting wiring board 25 having a wiring conductor 28a and a line conductor 24 for mounting corresponding to the connection electrode 28a and a part of the high-frequency semiconductor element 31 and the mounting wiring board 25 which are flip-chip mounted (sub-dielectric And a wiring board 21 having a concave portion 22a for accommodating the body layer 27). The mounting wiring board 25 has a main dielectric layer 26 and a sub-dielectric layer 27 having different relative dielectric constants. And a ground conductor is not formed on the exposed surface (upper surface) of the main dielectric layer 26 serving as the base, and the relative dielectric constant of the main dielectric layer 26 The dielectric constant of the main dielectric layer 26 is larger than the relative dielectric constant of the dielectric substrate 22 and the
The size of the recess 22 provided on the dielectric substrate 22 of the wiring board 21 is
The size of the sub-dielectric layer 27 is larger than the size of the opening of the recess 22a, and the mounting electrode 30 for flip-chip mounting with the high-frequency semiconductor element 31 is formed.
a is formed on the surface (lower surface) of the sub-dielectric layer 27, and the connection electrode 28a with the wiring board 21 is formed in a region around the lower surface of the main dielectric layer 26 where the sub-dielectric layer 27 is not laminated. The wiring between the connection electrodes 28a is formed on the main dielectric layer 26.
Mounting line conductor 28 formed at the interface between
And a through-conductor 30 formed in the sub-dielectric layer 27, and a wiring board 25 for mounting. The sub-dielectric layer 27 and the high-frequency semiconductor element 31 flip-chip mounted on the lower surface of the sub-dielectric layer 27 are mounted on the wiring board 21. The corresponding electrodes of the wiring board 21 and the mounting wiring board 25 are connected to each other while being accommodated in the recess 22a provided in the wiring board 21.

In the high-frequency semiconductor device of the present invention having such a structure, the main dielectric layer 26 forming the mounting wiring board 25 is formed.
Each of the sub-dielectric layers 27 may be a single layer made of a single dielectric material, and may be formed by laminating a plurality of dielectric layers to obtain a desired relative permittivity and other characteristics. A multi-layer structure may be used. As the main dielectric layer 26 and the sub-dielectric layer 27, for example, the main dielectric layer 26 is made of a ceramic material such as an aluminum oxide sintered body or an aluminum nitride sintered body. Polyimide or polytetrafluoroethylene (PTF
E) A dielectric resin material such as benzocyclobutene (BCB) may be used.

When the main dielectric layer 26 has a higher relative dielectric constant than the dielectric substrate 22 and the sub dielectric layer 27 has a lower relative dielectric constant than the main dielectric layer 26, ,
For example, from the practical dielectric materials for forming these materials, those having a relative dielectric constant of about 2 as small as about 2 to about 4 to 6 and those having a relative dielectric constant as large as 8 or more are selected. May be used in combination as appropriate. At this time, the relative permittivity of the dielectric substrate 22 and the sub-dielectric layer 27
The relative permittivity of the high-frequency semiconductor device may be the same or different as long as it is smaller than the main dielectric layer 26. May be appropriately selected depending on the conditions.

When the size of the main dielectric layer 26 is made larger than the opening size of the concave portion 22a, the size of the main dielectric layer 26 is set to be larger than the opening size by about の of the wavelength of the high-frequency signal or less. The size of the sub-dielectric layer 27 is
When the opening size is smaller than the opening size a, the size may be as close as possible to the opening size without affecting the working accuracy of the mounting.

The dielectric substrate 22 forming the wiring substrate 21
As for the dielectric material, a material similar to that of the mounting wiring board 25 may be used as long as it is a dielectric material having a relative dielectric constant smaller than that of the main dielectric layer 26. Similarly, a single layer or a multilayer structure may be used.

The concave portion 22 of the dielectric substrate 22 of the wiring substrate 21
The ground conductor 23a formed on the bottom surface of the mounting wiring board
The line conductor 28 formed at 25 and the wiring conductor 32 formed on the upper surface of the high-frequency semiconductor element 31 function as a ground for high-frequency signals.

Starting from the ground conductor 23a, the ground conductor 23
・ Line conductor 24 ・ Mounting line conductor 28 ・ Connection electrode 28a ・ Same-surface ground conductor 29 ・ Penetrating conductor 30 ・ Mounting electrode 30a ・ Wiring conductor 32 ・ Element ground conductor 33 ・ Ground through conductor 35 Various conductor materials used as the conductor may be used, and their shapes, dimensions, etc. may be appropriately selected according to their specifications.

Similarly, various materials used as high-frequency conductor bumps and solder for mounting may be used for the conductor bumps 34 and the solders 37, and the cover 36 such as a metal shield may be similarly used for the cover 36. What is necessary is just to select and apply various materials, shapes, dimensions, etc. used as a body.

Next, specific examples of the high-frequency semiconductor device of the present invention will be described.

First, on a main dielectric layer 26 made of alumina ceramics (having a relative dielectric constant of 9.6) having a thickness of 200 μm, copper wiring as a mounting line conductor 28 and a sub-layer made of polyimide having a thickness of 100 μm (having a relative dielectric constant of 3.4) are used. A dielectric layer 27 is formed as a thin film, a mounting electrode 30a is provided at a position corresponding to a terminal electrode of the high-frequency semiconductor element 31 on the surface of the polyimide layer, and is connected by a mounting line conductor 28 serving as an inner layer wiring and a through conductor 30 for mounting. The wiring substrate 25 was manufactured.

Further, three layers of glass ceramics (relative dielectric constant: 4.8) having a thickness of 150 μm are laminated, and two layers are hollowed out, thereby forming a recess 22a, that is, a wiring substrate comprising a dielectric substrate 22 having a cavity. 21 was produced. In the wiring board 21, the surface of the third layer is
A line conductor 24 and an input / output electrode as the wiring 21 and a ground conductor 23a on the surface of the first layer, that is, the bottom of the recess 22a, are each formed as a thick film by printing a copper paste and co-firing with the dielectric substrate 22. Ground conductor 23a
Is a wiring board 21 by a through conductor 35 for grounding penetrating the first layer.
And is electrically connected to the ground conductor 23 on the lower surface of the device.

A cover 36 made of an iron-nickel-cobalt alloy as a metal shield covering the entire wiring board 21 is provided at a position 300 μm above the surface of the third layer in the wiring board 21.

For evaluation of the characteristics of flip chip mounting, a line width of 80 μm was formed on a gallium arsenide substrate having a thickness of 100 μm.
m microstrip line conductors, and the input and output electrodes are 80 μm at 70 μm intervals from both ends of the signal line.
A substrate for evaluation as a high-frequency semiconductor element 31 having a coplanar line structure having a ground electrode of mx 80 μm is manufactured, and is mounted on a mounting wiring substrate 25 via a conductive bump 34 made of gold having a height of 20 μm. Flip chip mounting was performed.

The polyimide layer as the sub-dielectric layer 27 of the mounting wiring board 25 and the evaluation substrate as the high-frequency semiconductor element 31 are accommodated in the recess 22a while the alumina dielectric layer 26 as the main dielectric layer 26 is formed. The mounting structure in the high-frequency semiconductor device of the present invention was realized by connecting the exposed connection electrode 28a and the line conductor 24 of the wiring board 21 by solder 37.

On the other hand, as a comparative example, a mounting wiring having a microstrip line having a line width of 200 μm and a mounting electrode corresponding to a terminal electrode of an evaluation substrate as a high-frequency semiconductor element 31 on an alumina ceramic substrate having a thickness of 200 μm. A substrate was prepared, and a substrate for evaluation was flip-chip connected under the same conditions.

According to the mounting structure of the high-frequency semiconductor device of the present invention as described above, in the cross section taken along the line AA 'shown in FIG. The connection electrode 28a formed on the lower surface of the main dielectric layer 26 of the wiring substrate 25 is joined by solder 37,
The line width of the mounting line conductor 28 is 80 μm, and the mounting line conductor 28
The distance between the ground conductor 23a is 130 μm. 4 is a mounting line structure formed at the interface between the main dielectric layer 26 and the sub-dielectric layer 27 of the mounting wiring board 25, and the cross section of the mounting line conductor 28 is shown in FIG. The line width is 80 μm, and the interval between the mounting line conductor 28 and the ground conductor 23a is 80 μm.

FIG. 6 is a diagram showing the reflection characteristics of the cross-sectional structure along the line AA ′ and the cross-sectional structure along the line BB ′ in the high-frequency semiconductor device of the present invention. In FIG. 6, the horizontal axis represents the frequency (unit: GHz), and the vertical axis represents the reflection coefficient S11 (unit: d).
B), and the characteristic curve A indicated by the solid line is AA ′.
The characteristic curve B indicated by the broken line shows the frequency characteristic of the reflection coefficient S11 in the line section, and the reflection coefficient S11 in the BB 'line section.
2 shows the frequency characteristics of FIG. According to this, it is shown that any of the transmission line structures can realize a low reflection coefficient over a wide band. That is, in any of the transmission line structures, it is possible to realize a line width approximately equal to the line width of the wiring conductor 32 of the high-frequency semiconductor element 31 while maintaining impedance matching. This makes it possible to suppress a change in the line width of the mounting line conductor 28, so that good transmission characteristics can be realized even in the transmission of the entire mounting structure.

FIG. 7 is a diagram showing the cross-sectional structure taken along the line CC ′ in FIG. 1 and the propagation characteristics of the design values of the high-frequency semiconductor element 31. Here, an evaluation board as a high-frequency semiconductor element 31 is disposed 20 μm below a mounting wiring board 25 composed of a main dielectric layer 26 and a sub-dielectric layer 27 similar to the cross section taken along line BB ′ shown in FIG. ing. In FIG. 7, the horizontal axis represents the frequency (unit: GHz), and the vertical axis represents the imaginary part of the propagation constant, that is, the phase constant β (unit: rad / m). The characteristic curve C indicated by the solid line is obtained by distributing the air layer, the sub-dielectric layer 27, the main dielectric layer 26, and the air layer 38 between the evaluation substrate and the sub-dielectric layer 27 immediately above the evaluation substrate. However, since a material having a relatively low dielectric constant is selected for the sub-dielectric layer 27 laminated on the lower surface of the main dielectric layer 26, as shown in FIG. In the characteristics of the high-frequency semiconductor element indicated by, almost no change was observed in the phase characteristics.

FIG. 1 is a sectional view showing an overall view of the high-frequency semiconductor device of the present invention. As is clear from FIG. 2, the high-frequency semiconductor elements 31 are mounted on the mounting wiring board 25 by flip-chip mounting. Therefore, even if it is found after the mounting that a certain high-frequency semiconductor element 31 is defective, the main dielectric layer 26 of the wiring board 1 and the mounting wiring board 13 can be used.
In this case, it is possible to select a material that has higher mechanical strength than the high-frequency semiconductor element 31. As a result, it is possible to increase the degree of freedom in selecting a resin in manufacturing, and to replace the resin for each mounting wiring board 13. As a result, it is possible to improve the non-defective rate of the entire semiconductor device.

It should be noted that the above is only an example of the embodiment of the present invention, and the present invention is not limited to the embodiment. Various changes and improvements may be made without departing from the gist of the present invention. No problem.

[0042]

As described above, according to the high-frequency semiconductor device of the present invention, a wiring substrate having a recess for accommodating a high-frequency semiconductor element, having a line conductor formed around an opening and a ground conductor formed on a bottom surface, is provided. A high-frequency semiconductor element flip-chip mounted on the mounting wiring board is electrically connected to the line conductor of the wiring board via the mounting line conductor of the mounting wiring board, and is mounted in the recess. Yes,
Since this mounting wiring board is composed of a main dielectric layer having a large relative dielectric constant attached to the opening of the concave portion and a sub-dielectric layer having a small relative dielectric constant laminated on the high-frequency semiconductor element side,
Since a dielectric having a relative dielectric constant lower than that of a conventional mounting substrate can be arranged above the wiring portion formed inside and / or on the surface of the high-frequency semiconductor element, the high-frequency semiconductor when flip-chip mounting is performed. The amount of impedance deviation from the original impedance design of the wiring in the element can be kept low, and a dielectric having a relatively high relative dielectric constant is arranged below the wiring part of the high-frequency semiconductor element as in the past. As a result, the original design value of the characteristics of the high-frequency semiconductor element can be guaranteed as compared with the case where the impedance of the wiring becomes different from the design value and the desired circuit operation is not guaranteed.

The line width of the line conductor of the inner wiring in the mounting wiring board is determined by the thickness of the main dielectric layer and the sub-dielectric layer, and the grounding of the bottom surface of the concave portion formed on the wiring board from the surface of the sub-dielectric layer. By using the distance to the conductor,
This increases the degree of freedom in impedance design.
As a result, the amount of change in the line width of the line conductor can be kept extremely small, and a portion corresponding to a discontinuous point that causes reflection of a high-frequency signal can be eliminated, so that signal transmission characteristics do not deteriorate. Therefore, a high-frequency semiconductor device having good transmission characteristics for high-frequency signals is obtained.

Furthermore, since the high-frequency semiconductor element is mounted on the mounting wiring board having high mechanical strength and the mounting wiring board is mounted on the wiring board, even if a defective element occurs after mounting, the mounting is performed. Since the wiring board only needs to be replaced, the overall non-defective rate is improved when a multi-chip module is configured, compared to a conventional mounting structure in which it is difficult to replace defective elements after mounting by bare chip mounting. Can be easily achieved.

As described above, according to the present invention, it is possible to suppress the fluctuation of the impedance of the wiring after the mounting of the high-frequency semiconductor element, to eliminate the reflection of the high-frequency signal due to the change of the line width, and to prevent the defective element after the mounting. It is possible to provide a high-frequency semiconductor device that can be easily replaced and has a mounting structure improved in both high-frequency characteristics and manufacturing processes.

[Brief description of the drawings]

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

FIG. 2 is an enlarged sectional view of a main part of FIG.

FIG. 3 is a cross-sectional view of a principal part taken along line A-A ′ of FIG. 2;

FIG. 4 is a cross-sectional view of a principal part taken along line B-B 'of FIG.

FIG. 5 is a cross-sectional view of a principal part taken along line C-C ′ in FIG. 2;

FIG. 6 is a diagram showing reflection characteristics of a cross-sectional structure taken along line AA ′ and a cross-sectional structure taken along line BB ′ in the high-frequency semiconductor device of the present invention.

FIG. 7 is a diagram showing a cross-sectional structure taken along line CC ′ in the high-frequency semiconductor device of the present invention and a frequency characteristic of a phase constant of the high-frequency semiconductor element.

FIG. 8 is an enlarged sectional view of a main part showing an example of a conventional high-frequency semiconductor device.

[Explanation of symbols]

 21 ... Wiring board 22 ... Dielectric board 22a ... Recess 23,23a ... Ground conductor 24 ... Line conductor 25 ... Mounting wiring board 26 ... ···· Main dielectric layer 27 ····· Sub conductor layer 28 ····· Line conductor for mounting 28a ···· Connection electrode 30 ·························· Bump

Claims (1)

[Claims] 1. A wiring board having a concave portion for accommodating a high-frequency semiconductor element on an upper surface of a dielectric substrate, a line conductor formed around an opening of the concave portion, and a ground conductor formed on the lower surface and the bottom surface of the concave portion. And a mounting wiring board attached to the wiring board so as to cover the opening of the concave portion, and a connection electrode formed on the lower surface periphery is connected to the line conductor, and a mounting wiring board, A high-frequency semiconductor device comprising: a high-frequency semiconductor element electrically connected to a mounting electrode formed on a lower surface via a conductor bump, wherein the mounting wiring board is larger than an opening dimension of the concave portion, and A main dielectric layer having a larger relative dielectric constant than the dielectric substrate, a sub-dielectric layer smaller than the opening dimension laminated on the lower surface thereof, and having a lower relative dielectric constant than the main dielectric layer; and the main dielectric layer. Formed around the lower surface of A mounting line conductor formed from the connection electrode thus formed to the main dielectric layer and the sub-dielectric layer, and the mounting line conductor electrically connected to the mounting electrode formed on the lower surface of the sub-dielectric layer. And a through conductor connected to the high frequency semiconductor device.