JP5357136B2 - Transformer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transformer capable of improving conversion efficiency between a primary-side coil part and a secondary-side coil part. <P>SOLUTION: A lower coil part of a primary side is formed on a first metal layer 13, a coil part of a secondary side is formed on a second metal layer 14, and an upper coil part of the primary side is formed on a third metal layer 15. The coil part of the secondary side is formed between the lower coil part of the primary side and the upper coil part of the primary side. Accordingly, the combination of a signal current flowing through the upper coil part of the primary side and an induction current flowing through the lower coil part of the primary side can sufficiently confine magnetic flux (energy) to a transformer. As a result of this, the conversion efficiency between the coil parts of the primary side and the coil part of the secondary side can be improved by suppressing the degradation of coupling coefficient between the coil parts of the primary side and the coil part of the secondary side and suppressing the losses. Additionally, since the transformer can be manufactured by general semiconductor processes, the transformer has a small size. <P>COPYRIGHT: (C)2012,JPO&amp;INPIT

Description

  The present invention relates to a transformer, and more particularly to a transformer that is mounted on an electronic device and performs voltage conversion.

In recent years, with the increase in the number of electronic devices that can be carried, there has been a demand for smaller and thinner electronic devices. For this reason, integration of electronic components incorporated in these electronic devices is required. In particular, it is an important issue to integrate a magnetic element such as a transformer (transformer) that is mounted on an electronic device and performs voltage conversion on one integrated circuit.
Conventionally, as a transformer integrated on one integrated circuit, for example, the transformer of Patent Document 1 and the transformer 100 of Non-Patent Document 1 as shown in FIG. 15 are known. In the transformer of Non-Patent Document 1, a secondary coil portion is formed by wiring a conductor in a circular shape with a metal layer 101, and a primary side is formed by wiring a conductor in a circular shape with a metal layer 102 immediately above it. The coil portion is formed. As described above, the conventional transformer has a structure in which the primary side coil part and the secondary side coil part can be written with one stroke.

  Such a transformer is considered to generate an induced electromotive force in the secondary side coil part that cancels the magnetic flux change generated in the primary side coil part when a signal current flows through the primary side coil part. be able to. In this case, in order to increase the conversion efficiency, it is suitable that the primary side coil part and the secondary side coil part are physically close to each other.

JP-A-9-213530

“Transformer Topologies for mmW Integrated Circuits”, Bernardo Leite, Eric Kerherve, Jean-Bapriste Begeret, Dilier Belt, EUMA2009, p18

However, in conventional transformer structures such as Patent Literature 1 and Non-Patent Literature 1, the coil portions face each other only on the lower surface of the primary side coil portion and the upper surface of the secondary side coil portion. For this reason, magnetic flux (energy) is generated in the direction shown by the arrow in FIG. 16, and the magnetic flux cannot be completely confined in the transformer 100. Electromagnetic induction is performed between the primary side coil part and the secondary side coil part, but if the generated magnetic flux cannot be sufficiently confined, the primary side coil part and the secondary side coil part The coupling coefficient of is deteriorated. This was a major cause of loss.
Then, an object of this invention is to provide the transformer which can raise the conversion efficiency between the coil part of a primary side, and the coil part of a secondary side in view of said subject.

In order to achieve the above object, the transformer according to the present invention is configured as follows.
A first transformer according to the present invention includes a lower coil formed by wiring a one-turn conductor with a first metal layer stacked on a semiconductor substrate via a first insulating film. And the other coil portion formed by wiring a single conductor with a second metal layer laminated on the first metal layer via a second insulating film, One upper coil portion formed by wiring one turn of a conductor in a third metal layer laminated via a third insulating film on the second metal layer, The other coil part is formed between the lower coil part and the one upper coil part, the one lower coil part, the other coil part, The center of one upper coil part is coaxial, and the inner diameter of each coil part , Same size der is, a first via hole formed on the second insulating layer, said third conductor formed by filling in the second via hole formed in the insulating film, wherein It is formed on the same layer with the same metal layer as at least one of the one lower coil part and the one upper coil part, and extends from both ends of at least the one coil part. is a connection portion made of the transmission path for connecting with the outside, said the one of the lower coil portion and the one of the upper coil portion, that is connected in parallel via the connection portion and the conductor It is characterized by that.

According to the first transformer, the lower coil portion on the primary side is formed by wiring in the first metal layer, and wiring is performed in the second metal layer immediately above the first metal layer. A secondary coil portion is formed, and an upper coil portion on the primary side is formed by wiring with a third metal layer directly above the second metal layer, and the lower coil portion and the primary side on the primary side are formed. The secondary coil portion is formed between the upper coil portion and the upper coil portion . The center of the lower coil portion on the primary side, the secondary coil portion, and the upper coil portion on the primary side are coaxial, and the inner diameters of the coil portions are the same size. The For example, when a signal current flows through the upper coil portion on the primary side, an induced current flows through the coil portion on the secondary side. Furthermore, the current induced by the induced current flows through the lower coil portion of the primary side. And by synthesizing the signal current flowing in the upper coil portion on the primary side and the current induced by the induced current flowing in the lower coil portion on the primary side, the magnetic flux can be sufficiently confined in the transformer, The coupling coefficient of electromagnetic induction generated between the primary side coil part and the secondary side coil part is not deteriorated. For this reason, there is little loss and it becomes possible to make conversion efficiency high. Moreover, since it can be manufactured by a general semiconductor process, a small integrated circuit can be manufactured.

According to the first transformer above SL, the coil portion and the primary side of the lower side of the primary side and the upper coil portion, to be electrically connected via the connection portion, of the two primary It becomes possible to form a secondary coil portion between the coil portions.

A second transformer according to the present invention includes at least one of a shield wall portion formed along an outer surface of each coil portion and a shield wall portion formed along an inner surface. To do.
According to said 2nd transformer, it becomes possible to prevent that a magnetic flux leaks especially from the side surface of each coil part by a shield wall part.

The third transformer according to the present invention is characterized in that the shield wall portion is formed at the same time that a conductor is wired in each metal layer or a conductor is buried in each via hole.
According to the third transformer described above, the shield wall portion is not provided by forming the shield wall portion at the same time as forming the coil portion in the metal layer or burying the conductor in the via hole. It can be manufactured by the same process as the transformer.

The fourth transformer according to the present invention is characterized in that the third metal layer is an uppermost metal layer.
According to the fourth transformer, for example, a metal layer different from the first to third metal layers can be laminated on the third metal layer.
A fifth transformer according to the present invention is a floating shield formed by wiring a conductor with a shield-forming metal layer laminated via a shield-forming insulating film before laminating the first insulating film. It has the part.
According to said 5th transformer, it becomes possible to prevent that a magnetic flux leaks especially from the lower surface of a coil part by a floating shield part.

The sixth transformer according to the present invention is characterized in that the floating shield portion is formed by wiring a plurality of conductors having the same width at equal intervals in an inner region and an outer region of each coil portion. To do.
According to the sixth transformer described above, the floating shield portions are wired at equal intervals with a conductor having the same width. At this time, the width and interval of the conductor are made sufficiently shorter than the wavelength of the signal. As a result, the loss of the electric field can be prevented by preventing the electric field from reaching the semiconductor substrate and generating heat. Further, with respect to the magnetic field, it is possible to reduce the loss of the transformer by suppressing the generation of the induced electromotive force and preventing the magnetic flux from leaking. Moreover, a high shielding effect can be acquired by making the area | region which combined the area | region inside the lower part of a coil part, and the area | region outside that into a floating shield part.
The seventh transformer according to the present invention is characterized in that the floating shield portion is a lowermost metal layer.
According to the seventh transformer, for example, a shield-forming metal layer can be stacked on a metal layer different from the first to third metal layers.

  According to the present invention, the secondary coil is formed by forming the lower coil portion of the primary side by wiring the conductor in the first metal layer and wiring the conductor by the second metal layer immediately above the first metal layer. Forming a coil portion on the primary side and wiring a conductor on the third metal layer directly above the second metal layer to form an upper coil portion on the primary side, and the secondary side coil portion on the primary side It is formed between the lower coil part and the upper coil part on the primary side. Thereby, the magnetic flux can be sufficiently confined in the transformer, and the coupling coefficient of electromagnetic induction generated between the primary side coil part and the secondary side coil part is not deteriorated. Therefore, loss can be reduced and conversion efficiency can be increased. Moreover, since it can be manufactured by a general semiconductor process, a small integrated circuit can be manufactured.

1 is a perspective view showing a configuration of a transformer 10 according to a first embodiment of the present invention. It is a top view which shows the structure of the transformer 10 which concerns on 1st Embodiment of this invention. It is a schematic diagram which shows the manufacturing process of the transformer 10 which concerns on 1st Embodiment of this invention. It is a schematic diagram which shows the operation principle of the transformer 10 which concerns on 1st Embodiment of this invention. It is a perspective view which shows the structure of the transformer 20 which concerns on 2nd Embodiment of this invention. It is a top view which shows the structure of the transformer 20 which concerns on 2nd Embodiment of this invention. It is a schematic diagram which shows the manufacturing process of the transformer 20 which concerns on 2nd Embodiment of this invention. It is a perspective view which shows the structure of the transformer 30 which concerns on 3rd Embodiment of this invention. It is a top view which shows the structure of the transformer 30 which concerns on 3rd Embodiment of this invention. It is a schematic diagram which shows the structure of the floating shield part of the transformer 30 which concerns on 3rd Embodiment of this invention. It is a schematic diagram which shows the manufacturing process of the transformer 30 which concerns on 3rd Embodiment of this invention. It is a graph which shows the frequency-inductance characteristic of the primary side coil part and the secondary side coil part in the transformer 10 of this invention. It is a graph which shows the transmission characteristic of the transformer 10 of this invention, and the frequency-transfer characteristic with the conventional transformer. Frequency of transfer characteristic of the conventional transformer of the transformer 10 of the present invention - transfer characteristics is a graph showing the (inner diameter D ₁ of the coil portion is different three sets). It is a perspective view which shows the structure of the conventional transformer. It is a schematic diagram which shows the principle of operation of the conventional transformer.

Hereinafter, embodiments of a transformer according to the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted.
(First embodiment)
(Configuration of transformer 10)
First, with reference to FIG.1 and FIG.2, the structure of the transformer 10 which concerns on 1st Embodiment of this invention is demonstrated.
The transformer 10 shown in FIG. 1 includes a semiconductor substrate 11, a first insulating film 12a to a fourth insulating film 12d, a conductor formed on the first metal layer 13 to the third metal layer 15, and a first via hole. 16 and a conductor embedded in the second via hole 17.

The semiconductor substrate 11 is a substrate for forming a semiconductor element.
The first insulating film 12 a to the fourth insulating film 12 d are made of SiO ₂ , SiN, SiON, or the like, and are for protecting a semiconductor element formed on the semiconductor substrate 11. The first metal layer 13 to the third metal layer 15, the first via hole 16 and the second via hole 17 are covered on the semiconductor substrate 11 with the first insulating film 12a to the fourth insulating film 12d. However, for the sake of explanation, a part of the first insulating film 12a to the fourth insulating film 12d is omitted in each drawing.

The first metal layer 13 is a metal layer of the lowermost is a layer coil portion of the lower side of the primary side by the conductors are wired in a circle with an inner diameter D ₁ is formed.
The second metal layer 14 is a metal layer immediately above the first metal layer 13, and is a layer in which a secondary coil portion is formed by the conductor being circularly wired with an inner diameter D _1. .
The third metal layer 15 is a metal layer directly above the second metal layer 14, a layer conductor coil portion of the upper of the primary side by being wired in a circular shape in the inner diameter D ₁ is formed is there.

  In addition, at the same time as forming the coil portion with the first metal layer 13 to the third metal layer 15, the lower coil portion on the primary side and the upper coil portion on the primary side are electrically connected, A connection portion that forms a differential transmission line for connecting the coil portion and the outside world is formed. In the figure, a portion indicated by A is a coil portion, and a portion indicated by B is a connection portion. Further, in order to increase a coupling coefficient of electromagnetic induction generated between the primary side coil part and the secondary side coil part, the center of the coil part formed in the first metal layer 13 to the third metal layer 15 is used. O is coaxial, and the inner diameters are all the same size.

The first via hole 16 is a via hole between the first metal layer 13 and the second metal layer 14, and electrically connects the lower coil portion on the primary side and the upper coil portion on the primary side. The hole is formed in the second insulating film 12b in order to embed a conductor for connection.
The second via hole 17 is a via hole between the second metal layer 14 and the third metal layer 15 and electrically connects the lower coil portion on the primary side and the upper coil portion on the primary side. The hole is formed in the third insulating film 12c in order to embed a conductor for connection.

  As shown in FIGS. 1 and 2, a secondary coil portion is formed between a lower coil portion on the primary side and an upper coil portion on the primary side. Then, a connection portion connected to the lower coil portion on the primary side and a connection portion connected to the upper coil portion on the primary side are formed in the first via hole 16, the second metal layer 14, and the second via hole 17. Electrical connection is made through the connected portion. The primary side and the secondary side may be reversed.

(Manufacturing method of the transformer 10)
Next, a general manufacturing method of the transformer 10 according to the first embodiment of the present invention will be described with reference to FIG.
First, as shown in FIG. 3A, a first insulating film 12a is formed on a semiconductor substrate 11 by chemical vapor deposition, sputtering, spin coating, or the like. Next, as shown in FIG. 3B, the conductor on the lower side of the primary side is formed by wiring the conductor with the first metal layer 13 thereon by a metal vapor deposition method, a sputtering method, a plating method or the like. A coil part and a connection part are formed. Next, as shown in FIG. 3C, after the lower coil portion and the connection portion on the primary side are formed on the first metal layer 13, the second insulating film 12b is formed.

Next, as shown in FIG. 3D, after the second insulating film 12b is formed, the second insulating film 12b is formed by a dry etching technique using fluorine-based gas, bromine-based gas, iodine-based gas, or the like. A first via hole 16 is formed by burying a conductor for electrically connecting the lower coil portion on the primary side and the upper coil portion on the primary side into the first via hole 16.
Next, as shown in FIG. 3E, a secondary coil portion and a connection portion are formed by forming a conductor in a circular shape with the second metal layer 14 immediately above the first via hole 16. . Next, as shown in FIG. 3F, after the secondary coil portion and the connection portion are formed in the second metal layer 14, the third insulating film 12c is formed.

Next, as shown in FIG. 3G, after the third insulating film 12c is formed, a hole is formed in the third insulating film 12c by the dry etching technique to form the second via hole 17, and the second A conductor for electrically connecting the lower coil portion on the primary side and the upper coil portion on the primary side is embedded in the via hole 17.
Next, as shown in FIG. 3H, a conductor is formed in a circular shape with the third metal layer 15 immediately above the second via hole 17, thereby forming the upper coil portion and the connection portion on the primary side. To do. Next, as shown in FIG. 3I, after the upper coil portion and the connection portion on the primary side are formed in the third metal layer 15, the fourth insulating film 12d is formed.
The transformer 10 can be manufactured by such a process.

  In addition, although each coil part is formed by wiring the 1st metal layer 13-the 3rd metal layer 15 in a circle shape, it is not necessary to wire in a circle shape. For example, it can be wired in a polygonal shape. In the transformer 10 according to the present embodiment, the third metal layer 15 is the uppermost layer, but the third metal layer 15 is not necessarily the uppermost layer. For example, a metal layer different from the first metal layer 13 to the third metal layer 15 can be stacked on the third metal layer 15. The same applies to a transformer according to each embodiment described later.

(Operation principle of the transformer 10)
Next, the operation principle of the transformer 10 according to the first embodiment of the present invention will be described with reference to FIG.
First, a signal current flows through the upper coil portion on the primary side formed in the metal layer 15 in the direction indicated by the arrow in FIG. Then, an induced electromotive force is generated, and the induced current induced by the signal current flows through the secondary coil portion formed in the second metal layer 14 in the direction opposite to the signal current. Then, an induced electromotive force is generated again, and a current induced by the induced current flows in the same direction as the signal current through the lower coil portion of the primary side formed in the first metal layer 13.

  As described above, the transformer 10 has a structure in which the secondary coil portion is formed between the upper coil portion on the primary side and the lower coil portion on the primary side. That is, the coil portions face each other on the upper surface of the lower coil portion on the primary side and the lower surface of the coil portion on the secondary side, and further, the lower surface of the upper coil portion on the primary side and the upper surface of the secondary coil portion The coil parts are facing each other. Thereby, the signal current flowing in the upper coil portion on the primary side and the current induced by the induced current flowing in the lower coil portion on the primary side can be combined to sufficiently confine the magnetic flux in the transformer 10. . Thereby, the magnetic flux which leaks from the lower surface of the secondary side coil part which was the largest factor of loss decreases. Therefore, the loss of the transformer 10 can be reduced, that is, the conversion efficiency from the primary side to the secondary side can be increased. Further, since the transformer 10 can be manufactured by a general semiconductor process, the transformer 10 is small.

(Second Embodiment)
(Configuration of the transformer 20)
Next, with reference to FIG.5 and FIG.6, the structure of the transformer 20 which concerns on 2nd Embodiment of this invention is demonstrated.
The transformer 20 shown in FIGS. 5 and 6 has the same configuration as that of the transformer 10 shown in FIGS. 1 and 2, but in order to prevent the magnetic flux from leaking from the side surfaces of the coil portions. A shield wall portion is formed along each coil portion on the outer surface of each coil portion.
The third via hole 21 is a via hole between the semiconductor substrate 11 and the first metal layer 13, and is a hole opened in the first insulating film 12a in order to embed a conductor serving as a shield wall portion. .

The shield wall portion has the same center position of the coil portion formed in the first metal layer 13 to the third metal layer 15 and has an inner diameter D ₂ larger than the inner diameter D _{1 of the} coil portion. That is, the shape of the shield part when viewed from above is similar to the shape of the coil part.
In the transformer 20, since the shield wall part is formed outside each coil part, the magnetic flux leaking from the side surface direction of the primary coil part and the secondary coil part is reduced. Moreover, since there is no return path in the shield wall, it is possible to prevent magnetic flux from leaking out. Furthermore, the shield wall portion forms a shield wall portion with a small resistance component, that is, a low loss by connecting with the primary side coil portion at the shortest distance with the midpoint potential (common potential) of the primary side coil portion. be able to.

In this way, the transformer 20 can further reduce the loss than the transformer 10, that is, increase the conversion efficiency from the primary side to the secondary side.
In addition, this shield wall part can also be formed in the inner surface of a coil part besides the outer surface of a coil part, or can be formed in the outer surface and inner surface of a coil part. The shield wall is not necessarily formed by all of the first metal layer 13 to the third metal layer 15, the first via hole 16, the second via hole 17, and the third via hole 21.

(Manufacturing method of the transformer 20)
Next, a general manufacturing method of the transformer 20 according to the second embodiment of the present invention will be described with reference to FIG.
First, as shown in FIG. 7A, a first insulating film 12a is formed on a semiconductor substrate 11 by a chemical vapor deposition method, a sputtering method, a spin coating method, or the like. Next, as shown in FIG. 7B, after forming the first insulating film 12a, a hole is formed in the first insulating film 12a by the dry etching technique to form the third via hole 21, and the third A conductor serving as a shield wall is embedded in the via hole 21.
Thereafter, in the same process as the transformer 10 described above, as shown in FIGS. 7C and 7D, a coil portion and a connection portion are formed in the metal layer, or a conductor is embedded in the via hole. At the same time, a shield wall may be formed.

(Third embodiment)
(Configuration of transformer 30)
Next, with reference to FIGS. 8-10, the structure of the transformer 30 which concerns on 3rd Embodiment of this invention is demonstrated.
The transformer 30 shown in FIGS. 8 and 9 has the same configuration as the transformer 10 shown in FIGS. 1 and 2, but includes a shield-forming metal layer 31 and a shield-forming insulating film 32. In particular, in order to prevent magnetic flux from leaking from the lower surface of the coil portion, a floating shield portion is formed in the shield forming metal layer 31 below the coil portion.
The shield forming metal layer 31 is the lowermost metal layer, and is a layer in which a floating shield portion is formed by wiring a plurality of rod-shaped conductors.

The shield forming insulating film 32 is an insulating film made of SiO ₂ or the like, like the first insulating film 12a to the fourth insulating film 12d, and protects a semiconductor element formed on the semiconductor substrate 11. Is.
In this floating shield part, an upper coil on the primary side formed in the first metal layer 13 so as to enhance self-resonance and further reduce layout constraints when being integrated as a semiconductor. A plurality of rod-shaped conductors in a direction that is 90 degrees with respect to the wiring direction of the conductor of the connection portion connected to the connection portion and the conductor of the connection portion connected to the secondary coil portion formed in the second metal layer 14. Wired. All the conductors are wired with a width a, and the conductors are wired with an interval of a width b. The widths a and b are made sufficiently shorter than the signal wavelength. By reducing the distance between the conductors to be shorter than the wavelength, the electric field is prevented from reaching the semiconductor substrate 11 and generating heat, and the loss of the transformer 30 is reduced. Further, with respect to the magnetic field, the loss of the transformer 30 is reduced by suppressing the generation of the induced electromotive force and preventing the magnetic flux from leaking.

In addition, the floating shield part is formed in the first metal layer 13 to the third metal 15 with the center positions of the coil parts formed in the first metal layer 13 to the third metal layer 15 being the same. that is a larger inner diameter D ₃ than the inner diameter D ₁ of the respective coil portions. That is, a floating shield portion is formed by combining a region inside the lower portion of each coil portion and a region outside the coil portion. By making the inner diameter D ₃ larger than the inner diameter D ₁ , a high shielding effect can be obtained.

The preferable structure of the floating shield part will be clarified from the viewpoint of the electric field.
First, when the electric field reaches the semiconductor substrate 11, heat is generated, that is, loss occurs. For this reason, it is preferable that a floating shield part encloses the surrounding conductor largely. Further, the resistance of the floating shield part is preferably as low as possible so that the electric field reaches the ground. Further, considering the application at high frequency, it is preferable that the parasitic capacitance between the conductor wired in the shield forming metal layer 31 and the conductor wired in each metal layer is as small as possible. Accordingly, as shown in FIG. 10A, the floating shield portion is formed by wiring a plurality of conductors having the same width a to the shield forming metal layer 31 below the coil portion at intervals of the width b. Is preferably sufficiently shorter than the signal wavelength.

Also, the preferred structure of the floating shield part will be clarified from the viewpoint of the magnetic field.
The transformer 30 is a passive element that uses an induced electromotive force. For this reason, it is preferable that a floating shield part does not give a magnetic influence as much as possible. Therefore, as shown in FIG. 10B, the conductor of the floating shield part is preferably as far as possible from the surrounding conductors in the direction of 90 degrees with respect to the wiring direction of the conductor of the connection part.
In the transformer 30 according to the present embodiment, the shield forming metal layer 31 is the bottom layer, but the shield forming metal layer 31 is not necessarily the bottom layer. For example, the shield forming metal layer 31 may be laminated on a metal layer different from the first metal layer 13 to the third metal layer 15.

(Method for manufacturing transformer 30)
Next, a general manufacturing method of the transformer 30 according to the third embodiment of the present invention will be described with reference to FIG.
First, as shown in FIG. 11A, a shield forming insulating film 32 is formed on the semiconductor substrate 11 by chemical vapor deposition, sputtering, spin coating, or the like. Next, as shown in FIG. 11B, a floating shield portion is formed by wiring a conductor with the shield forming metal layer 31 immediately above by metal vapor deposition, sputtering, plating, or the like.
By forming the floating shield part before forming the coil part and the connection part, the process similar to that of the above-described transformer 10 is performed as shown in FIGS. 11 (c) and 11 (d). The transformer 30 can be manufactured.

(Inductance vs. frequency characteristics)
Next, with reference to FIG. 12, the experimental result of the frequency-inductance characteristic in the transformer 10 according to the first embodiment and the conventional transformer will be described.
The horizontal axis of the graph of FIG. 12 indicates the frequency, and the vertical axis indicates the inductance of the primary coil portion and the secondary coil portion of each transformer. Note that the transformer 10 forms the primary coil portion in the first metal layer 13 and the third metal layer 15 and forms the secondary coil portion in the second metal layer 14 as described above. Then, a secondary coil portion is formed between the primary coil portions. On the other hand, in the conventional transformer, only the primary side coil portion formed in the third metal layer 15 of the transformer 10 and the secondary side coil portion formed in the second metal layer 14 are vertically connected. It is a pile.
As shown in FIG. 12, when the self-resonant frequency of the transformer 10 is about 26 GHz and the frequency is between about 8 GHz and about 15 GHz, the inductance of the primary side coil portion and the secondary side coil of the two transformers are used. It can be seen that the inductance of the part is substantially constant regardless of the winding ratio.

(Frequency-transfer characteristics)
Next, referring to FIG. 13 and FIG. 14, experimental results of frequency-transfer characteristics in the transformer 10 according to the first embodiment and the conventional transformer will be described.
The horizontal axis of the graphs of FIGS. 13 and 14 indicates the frequency, and the vertical axis indicates the transmission level from the primary side coil part of the transformer to the secondary side coil part.
As shown in FIG. 13, the transformer 10 has a transmission level of about 3 dB greater near the frequency of about 10 GHz than the conventional transformer, and about 1 dB greater even near the frequency of about 20 GHz. That is, it can be seen that the transformer 10 has much less loss than the conventional transformer. This effect is obtained in all frequency bands whose frequency is about 26 GHz or less of the self-resonant frequency.

Further, as shown in FIG. 14, in the transformer 10 according to the first embodiment and the conventional transformer, three sets of frequency-transfer characteristics having different inner diameters D ₁ of the coil portions are the conventional transformers in any case. It can be seen that the transformer 10 has less loss than the transformer. That is, regardless of the size of the inner diameter D ₁ of the coil portion, the transformer 10 has a significantly higher conversion efficiency than the conventional transformer. Incidentally, when the inner diameter D ₁ of the coil part A, B, and C, and A>B> C.

  The transformer according to the present invention is integrated as an electronic component and can be used by being mounted on a portable electronic device or the like.

10, 20, 30 Transformer 11 Semiconductor substrate 12a First insulating film 12b Second insulating film 12c Third insulating film 12d Fourth insulating film 13 First metal layer 14 Second metal layer 15 Third Metal layer 16 First via hole 17 Second via hole 21 Third via hole 31 Metal layer for shield formation 32 Insulating film for shield formation

Claims (7)

One lower coil portion formed by wiring a one-turn conductor on a semiconductor substrate with a first metal layer laminated via a first insulating film;
On the first metal layer, the other coil portion formed by wiring one turn of the conductor in the second metal layer laminated via the second insulating film,
On the second metal layer, one upper coil portion formed by wiring a one-turn conductor with a third metal layer laminated via a third insulating film;
With
The other coil part is formed between the one lower coil part and the one upper coil part,
A coil portion of the one of the lower, and the other coil portion, a center of said one of the upper coil portions are coaxial, and the inner diameter of the respective coil portions, Ri same size der,
A conductor formed by embedding the first via hole formed in the second insulating film and the second via hole formed in the third insulating film;
It is formed on the same layer with the same metal layer as at least one of the one lower coil part and the one upper coil part, and extends from both ends of at least the one coil part. And a connection part that is a transmission path for connecting to the outside,
Wherein the one of the lower coil portion and the one of the upper coil portion, transformer characterized that you have connected in parallel through the connecting portion and the conductor. The transformer according to claim 1, further comprising at least one of a shield wall portion formed along an outer surface of each coil portion and a shield wall portion formed along an inner surface. 3. The transformer according to claim 2 , wherein the shield wall portion is formed at the same time that a conductor is wired to each metal layer or a conductor is buried in each via hole. The transformer according to any one of claims 1 to 3 , wherein the third metal layer is an uppermost metal layer. 2. A floating shield portion formed by wiring a conductor with a shield forming metal layer stacked via a shield forming insulating film before the first insulating film is stacked. Item 5. The transformer according to any one of Items 1 to 4 . The transformer according to claim 5 , wherein the floating shield part is formed by wiring a plurality of conductors having the same width at equal intervals in an inner region and an outer region of each coil part. The transformer according to claim 5 or 6 , wherein the floating shield portion is a lowermost metal layer.

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