JP4818894B2 - High frequency transmission line - Google Patents

Description

  The present invention relates to a signal transmission line, and particularly to a high-frequency transmission line having a microstrip line structure.

  FIG. 7 is a configuration diagram of a conventional signal transmission line. This signal transmission line includes a silicon substrate 10, a metal thin film (ground conductor) 20, an insulating film 30, and a metal thick film (strip conductor) 40 (see, for example, Patent Document 1).

Next, the operation of the conventional high-frequency transmission line having such a configuration will be described.
The signal transmission line according to the conventional invention has a microstrip line structure in which the ground conductor is composed of the metal thin film 20, the substrate is composed of the insulating film 30, and the strip conductor is composed of the metal thick film 40. The X direction in FIG. 7 corresponds to the width direction of the strip conductor, and the y direction corresponds to the height direction of the strip conductor, and the high-frequency signal propagates in the Z direction. Most of the electromagnetic field of the high-frequency signal propagating in the Z direction is distributed in the insulating film 30 corresponding to the substrate of the microstrip line.

  The characteristic impedance of the microstrip line is determined by the thickness and relative dielectric constant of the insulating film 30 corresponding to the substrate of the microstrip line and the width of the metal thick film 40 corresponding to the strip conductor of the microstrip line.

JP-A-5-37207

However, the prior art has the following problems.
Since the conventional signal transmission line constitutes a microstrip line, the metal thin film 20 corresponding to the ground conductor of the microstrip line has to be provided uniformly over a wide area on the silicon substrate 10. However, in the silicon semiconductor process, there is a problem in that in forming the metal film, the metal cannot be provided uniformly over a wide area for reliability. On the other hand, there is also a problem that a metal film is required with a certain occupation ratio.

  The present invention has been made to solve the above-described problems, and an object thereof is to obtain a high-frequency transmission line that can be realized by a silicon semiconductor process without deteriorating the high-frequency characteristics of the microstrip line.

A high-frequency transmission line according to the present invention is formed on a silicon semiconductor substrate and forms a grounding conductor in the microstrip line, an insulating film that is formed on the metal thin film and forms a substrate in the microstrip line, and insulation In a high frequency transmission line formed by a silicon semiconductor process , the metal thin film has a width of the metal thick film corresponding to the width of the strip conductor. direction of the center and, have a first slit group including a plurality of slits beneath the thick metal film, a first slit group provided on the metal thin film is located less than half the slit width is the width of the thick metal film The slit length is composed of a plurality of slits that are equal to the width of the metal thick film .

  According to the present invention, a slit is provided in a specific portion of a metal thin film corresponding to the ground conductor of the microstrip line, and the area of the metal thin film is reduced, thereby realizing the silicon semiconductor process without deteriorating the high frequency characteristics of the microstrip line. A possible high-frequency transmission line can be obtained.

  Hereinafter, preferred embodiments of the high-frequency transmission line of the present invention will be described with reference to the drawings.

Embodiment 1 FIG.
FIG. 1 is a configuration diagram of a high-frequency transmission line according to Embodiment 1 of the present invention. 1 includes a silicon substrate 10, a metal thin film (ground conductor) 20, an insulating film 30, and a metal thick film (strip conductor) 40. Such a configuration is the same as the basic configuration of the conventional high-frequency transmission line shown in FIG.

  However, the high-frequency transmission line according to the first embodiment is different in that the first slit group 21 including a plurality of slits is further provided on the metal thin film 20. The first slit group 21 in FIG. 1 is provided on the metal thin film 20 corresponding to the center in the width direction of the metal thick film 40 (corresponding to the X direction in FIG. 1) and directly below.

  Next, the operation of the high-frequency transmission line according to the first embodiment having such a configuration will be described. The high-frequency transmission line according to the first embodiment has a microstrip line structure in which the ground conductor is composed of the metal thin film 20, the substrate is composed of the insulating film 30, and the strip conductor is composed of the metal thick film 40. In FIG. 1, the X direction corresponds to the width direction of the strip conductor, the Y direction corresponds to the height direction of the strip conductor, and the high-frequency signal propagates in the Z direction. Most of the electromagnetic field of the high-frequency signal propagating in the Z direction is distributed in the insulating film 30 corresponding to the substrate of the microstrip line.

  The characteristic impedance of the microstrip line is determined by the thickness and relative dielectric constant of the insulating film 30 corresponding to the substrate of the microstrip line and the width of the metal thick film 40 corresponding to the strip conductor of the microstrip line.

  The thickness of the insulating film 30 is about several μm to several tens of μm realized by the silicon semiconductor process. For example, in the case of a microstrip line having a characteristic impedance of 50Ω, when the relative dielectric constant of the insulating film 30 is about 5, the strip conductor width is about 10 μm.

  The first slit group 21 provided in the metal thin film 20 corresponding to the ground conductor of the microstrip line is provided only directly below the central portion where the current density of the metal thick film 40 which is the strip conductor of the microstrip line is the lowest. For this reason, even when the first slit group 21 is provided, it is possible to minimize the deterioration of the high frequency characteristics including the passage loss of the microstrip line.

  Furthermore, since the area of the metal thin film 20 can be reduced by providing the first slit group 21, it is not necessary to uniformly provide a metal over a wide area, and the formation of the metal film is facilitated. Furthermore, by forming the first slit group 21 with a plurality of slits and providing a connecting portion between each slit, the potential difference between the left and right can be eliminated.

  As described above, according to the first embodiment, the slit of the metal thin film corresponding to the ground conductor of the microstrip line is provided, and the area of the metal thin film is reduced, so that the high-frequency signal propagating through the microstrip line is deteriorated. Can be minimized, and a high-frequency transmission line that can be realized by a silicon semiconductor process can be obtained.

Embodiment 2. FIG.
FIG. 2 is a configuration diagram of a high-frequency transmission line according to Embodiment 2 of the present invention. The configuration of the high-frequency transmission line in the second embodiment shown in FIG. 2 is the first slit provided on the metal thin film 20 as compared with the configuration of the high-frequency transmission line in the first embodiment shown in FIG. The shape of the group 22 is different. 2, the same reference numerals as those in FIG. 1 denote the same or corresponding parts, and the description thereof is omitted.

  The first slit group 22 in FIG. 2 is provided on the metal thin film 20 corresponding to the center in the width direction of the metal thick film 40 and the position directly below. Further, the slit width (corresponding to the X direction in FIG. 2) of the first slit group 22 in FIG. 2 is not more than half the width of the metal thick film 40 corresponding to the strip conductor, and the slit length (corresponding to the Z direction in FIG. 2). Is approximately the same as the width of the metal thick film 40.

  The first slit group 22 provided in the metal thin film 20 corresponding to the ground conductor of the microstrip line has such dimensions, and the center of the metal thick film 40 that is the strip conductor of the microstrip line has the lowest current density. The first slit group can be provided only directly under the portion. For this reason, even when the first slit group 22 is provided, it is possible to minimize the deterioration of the high frequency characteristics including the passage loss of the microstrip line.

  Furthermore, since the area of the metal thin film 20 can be reduced by providing the first slit group 22, it is not necessary to uniformly provide a metal over a wide area, and the metal film can be easily formed. Furthermore, by forming the first slit group 22 with a plurality of slits and providing a connecting portion between the slits, the potential difference between the left and right can be eliminated.

  As described above, according to the second embodiment, in addition to the effects of the first embodiment, the slit width and the upper limit value of the slit length for achieving the improved performance are provided, thereby having the slit. Design of metal thin film becomes easy.

Embodiment 3 FIG.
FIG. 3 is a configuration diagram of a high-frequency transmission line according to Embodiment 3 of the present invention. The configuration of the high-frequency transmission line according to the third embodiment shown in FIG. 3 is a group of slits provided on the metal thin film 20 as compared with the configuration of the high-frequency transmission line according to the second embodiment shown in FIG. In addition to the first slit group 22, the second slit group 22a and the third slit group 22b are further different. 3, the same reference numerals as those in FIG. 2 denote the same or corresponding parts, and the description thereof is omitted.

  In FIG. 3, the first slit group 22 on the metal thin film 20 is provided at the center in the width direction of the metal thick film 40 and directly below, as in the second embodiment. Further, in the present third embodiment, the second slits are formed on both sides of the first slit group 22 with a space more than the width of the metal thick film 40 from the first slit group 22 on the left and right sides of the first slit group 22. A group 22a and a third slit group 22b are provided.

  More specifically, the first slit group 22 provided in the metal thin film 20 corresponding to the ground conductor of the microstrip line is similar to the second embodiment in that the metal thick film 40 that is the strip conductor of the microstrip line is formed. It is provided only directly below the central portion with the lowest current density. For this reason, even when the first slit group 22 is provided, it is possible to minimize the deterioration of the high frequency characteristics including the passage loss of the microstrip line.

  Further, by providing the second slit group 22a and the third slit group 22b in addition to the first slit group 22, the area of the metal thin film 20 can be further reduced, so that the metal is uniformly distributed over a wide area. There is no need to provide it, and the formation of the metal film is facilitated.

  As described above, according to the third embodiment, in addition to the effect of the second embodiment, the area of the metal thin film can be further reduced by further providing the second slit group and the third slit group. This eliminates the need to uniformly provide a metal over a wide area, and facilitates the production of a high-frequency transmission line by a silicon semiconductor process.

  3 shows a case in which the second slit group and the third slit group are added to the configuration of FIG. 2, but the second slit group and the third slit group are added to the configuration of FIG. It is also possible to add, and the same effect can be obtained.

Embodiment 4 FIG.
FIG. 4 is a configuration diagram of a high-frequency transmission line according to Embodiment 4 of the present invention. Compared with the configuration of the high-frequency transmission line in the second embodiment shown in FIG. 2, the configuration of the high-frequency transmission line in the fourth embodiment shown in FIG. The difference is that it is limited to not less than 2 times and not more than 3 times the width. 4, the same reference numerals as those in FIG. 2 denote the same or corresponding parts, and the description thereof is omitted.

  The first slit group 22 provided in the metal thin film 20 corresponding to the ground conductor of the microstrip line has the lowest current density of the metal thick film 40 that is the strip conductor of the microstrip line, as in the second embodiment. It is provided only directly under the part. For this reason, it is possible to minimize the deterioration of the high frequency characteristics including the passage loss of the microstrip line.

  Furthermore, the width of the metal thin film 20 in the fourth embodiment is suppressed to be not less than 2 times and not more than 3 times the width of the metal thick film 40 as an allowable range that does not deteriorate the high frequency characteristics. As a result, since the area of the metal thin film 20 can be further reduced, it is not necessary to uniformly provide a metal over a wide area, and the metal film can be easily formed.

  As described above, according to the fourth embodiment, in addition to the effects of the second embodiment, by defining the width of the metal thin film, the area of the metal thin film can be further reduced, and the metal is spread over a wide area. Therefore, it is not necessary to uniformly provide a high-frequency transmission line by a silicon semiconductor process.

  4 shows a case where the width of the metal thick film is suppressed as compared with the configuration of FIG. 2, the width of the metal thick film can be suppressed as compared with the configuration of FIG. The effect of can be obtained.

  4 shows a case where the width of the metal thick film is suppressed as compared with the configuration of FIG. 2, but in addition to this, as shown in FIG. 3, the second slit group, It is also possible to add a third slit group, and in this case, the same effect as the effect described in the third embodiment can be obtained.

Embodiment 5 FIG.
FIG. 5 is a configuration diagram of a high-frequency transmission line according to Embodiment 5 of the present invention. The configuration of the high-frequency transmission line in the fifth embodiment shown in FIG. 5 is the first slit provided on the metal thin film 20 as compared with the configuration of the high-frequency transmission line in the fourth embodiment shown in FIG. The shape of the group 23 is different. 5, the same reference numerals as those in FIG. 4 denote the same or corresponding parts, and the description thereof will be omitted.

  The first slit group 23 in FIG. 5 is formed of an elliptical shape in which a plurality of slits are not rectangular but have corners removed. Furthermore, the first slit group 23 provided in the metal thin film 20 is provided at the center in the width direction of the metal thick film 40 and directly below, as in the first to fourth embodiments. Furthermore, the width of the metal thin film 20 is suppressed to 2 times or more and 3 times or less of the width of the metal thick film 40 as in the fourth embodiment.

  The first slit group 23 formed in an elliptical shape provided in the metal thin film 20 corresponding to the ground conductor of the microstrip line is directly below the central portion where the current density of the metal thick film 40 which is the strip conductor of the microstrip line is the lowest. Only provided. For this reason, it is possible to minimize the deterioration of the high frequency characteristics including the passage loss of the microstrip line. Furthermore, since there are no corners in the slit, current density discontinuities can be eliminated.

  In addition, the width of the metal thin film 20 in the fifth embodiment is suppressed to not less than 2 times and not more than 3 times the width of the metal thick film 40 as an allowable range in which the high frequency characteristics are not deteriorated, as in the fourth embodiment. It has been. As a result, since the area of the metal thin film 20 can be further reduced, it is not necessary to uniformly provide a metal over a wide area, and the metal film can be easily formed.

  As described above, according to the fifth embodiment, in addition to the effects of the fourth embodiment, by disposing the slit into an elliptical shape, current density discontinuities can be eliminated, and better high-frequency characteristics can be obtained. Can be realized.

  5 shows a case where the slit is elliptical with respect to the configuration of FIG. 4, the elliptical slit can also be applied to the configuration of FIGS. 1 to 3. Yes, the same effect can be obtained.

Embodiment 6 FIG.
FIG. 6 is a configuration diagram of a high-frequency transmission line according to Embodiment 6 of the present invention. The configuration of the high-frequency transmission line in the sixth embodiment shown in FIG. 6 is different from the configuration of the high-frequency transmission line in the previous fifth embodiment shown in FIG. And a multilayer structure composed of a combination of the laminated metal thin films 24a, 24b, 25a, 25b, the vias 26a, 26b, 27a, 27b, 28a, 28b, and the ground conductor metal thick films 40a, 40b. Is different. 6, the same reference numerals as those in FIG. 5 denote the same or corresponding parts, and the description thereof will be omitted.

  As shown in FIG. 6, the laminated metal thin films 24a and 24b are respectively provided on the upper left and right ends of the metal thin film 20 with the insulating film 30 interposed therebetween, and are connected to the metal thin film 20 by vias 26a and 26b. Further, the laminated metal thin films 24a and 24b are arranged so as to be separated from the metal thick film 40 with the insulating film 30 interposed therebetween by a distance corresponding to the separation distance (d in FIG. 6) between the metal thick film 40 and the metal thin film 20. Has been.

  The laminated metal thin films 25a and 25b are provided above the laminated metal thin films 24a and 24b with the insulating film 30 interposed therebetween, and are connected to the laminated metal thin films 24a and 24b by vias 27a and 27b, respectively. . Further, the laminated metal thin films 25 a and 25 b are arranged to be separated from the metal thick film 40 with the insulating film 30 interposed therebetween by a distance corresponding to the separation distance between the metal thick film 40 and the metal thin film 20.

  The thick metal films 40a and 40b for the ground conductor are the upper portions of the laminated metal thin films 25a and 25b with the insulating film 30 interposed therebetween, and the metal thick film 40 is sandwiched on the same plane as the metal thick film 40. It is provided on the left and right, and is connected to each of the laminated metal thin films 25a and 25b by vias 28a and 28b. Further, the thick metal films 40a and 40b for grounding conductors are spaced apart from the thick metal film 40 by a distance corresponding to the distance between the thick metal film 40 and the thin metal film 20.

  With this configuration, a ground conductor having a multilayer structure can be formed, and the metal conductor is separated from the metal thick film 40 by a distance corresponding to the distance between the metal thick film 40 and the metal thin film 20. The thick film 40 can be surrounded by a ground conductor having this multilayer structure.

  As a result, it is possible to increase the occupation ratio of the metal film of each layer serving as the ground conductor, and to realize a coaxial line structure in which the metal thick film 40 is surrounded by the ground conductor. Furthermore, in addition to the effect of the first slit group 23, by adopting a laminated structure, it is possible to reduce the area of each metal thin film, so that it is not necessary to uniformly provide a metal over a wide area. Formation becomes easy.

  As described above, according to the sixth embodiment, in addition to the effect of the fifth embodiment, a high-frequency transmission line having a coaxial line structure can be realized by surrounding the metal thick film with a ground conductor having a multilayer structure. A transmission line resistant to noise can be formed.

  In the above-described sixth embodiment, the case where the stacked metal films are three layers is shown, but the number is not limited to three. If necessary, a laminated structure of two layers or four or more layers can be applied, and the same effect can be obtained.

  6 shows a case where a grounded conductor having a laminated structure is applied to the structure of FIG. 5, but a grounded conductor having a laminated structure is also applied to the structures of FIGS. Can be applied, and similar effects can be obtained.

It is a block diagram of the high frequency transmission line in Embodiment 1 of this invention. It is a block diagram of the high frequency transmission line in Embodiment 2 of this invention. It is a block diagram of the high frequency transmission line in Embodiment 3 of this invention. It is a block diagram of the high frequency transmission line in Embodiment 4 of this invention. It is a block diagram of the high frequency transmission line in Embodiment 5 of this invention. It is a block diagram of the high frequency transmission line in Embodiment 6 of this invention. It is a block diagram of the conventional signal transmission line.

Explanation of symbols

  10 silicon substrate (silicon semiconductor substrate), 20 metal thin film (ground conductor), 21, 22, 23 first slit group, 22a second slit group, 22b third slit group, 24a, 24b, 25a, 25b laminated metal thin film ( Ground conductor), 26a, 26b, 27a, 27b, 28a, 28b Via, 30 Insulating film (substrate), 40 Metal thick film (strip conductor), 40a, 40b Metal thick film for ground conductor.

Claims (5)

A metal thin film formed on a silicon semiconductor substrate and constituting a ground conductor in a microstrip line;
An insulating film formed on the metal thin film and constituting a substrate in the microstrip line;
A high-frequency transmission line formed on a silicon semiconductor process, comprising a metal thick film formed on the insulating film and constituting a strip conductor in the microstrip line.
The metal thin film, the width direction of the center of the thick metal film corresponding to the width of the strip conductor and, have a first slit group including a plurality of slits beneath the thick metal film,
The first slit group provided in the metal thin film includes a plurality of slits having a slit width equal to or less than half of the width of the metal thick film and a slit length equal to the width of the metal thick film. High-frequency transmission line characterized by In the high frequency transmission line according to claim 1 ,
The high-frequency transmission line, wherein the plurality of slits constituting the first slit group are elliptical. In the high frequency transmission line according to claim 1 or 2 ,
The metal thin film has a second slit group and a third slit group having the same dimensions as the first slit group on both the left and right sides of the first slit group, with an interval greater than the width of the metal thick film. Furthermore, the high frequency transmission line characterized by having. In the high frequency transmission line according to any one of claims 1 to 3 ,
The width of the metal thin film is not less than 2 times and not more than 3 times the width of the metal thick film. In the high frequency transmission line according to any one of claims 1 to 4 ,
The metal thin film is connected via vias at both left and right ends, and is separated from the metal thick film by a distance corresponding to the separation distance between the metal thick film and the metal thin film, and is laminated on the upper left and right ends of the metal thin film. A laminated metal thin film provided and
Connected to each of the laminated metal thin films through vias, separated from the metal thick film by a distance corresponding to the separation distance between the metal thick film and the metal thin film, and on the left and right on the same plane as the metal thick film A high frequency transmission line, further comprising: a metal thick film for grounding conductor provided.

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