JP6327639B2 - Right angle solenoid inductor - Google Patents

Description

  The present invention relates to a technique for integrating a plurality of inductors at a high density or realizing a small high inductance value in an on-chip inductor formed on a semiconductor substrate such as silicon.

Conventionally, as a technique for realizing a small and high-inductance on-chip inductor, a three-dimensional solenoid inductor structure using a plurality of metal wiring layers provided on a semiconductor substrate has been proposed (for example, Non-Patent Document 1). Etc.)
FIG. 10 is an external view showing a configuration of a conventional solenoid inductor. In this solenoid inductor, a planar inductor wound on a plurality of wiring layers is connected in series, whereby a multi-winding inductor is formed on-chip, and a small-sized inductor having a high inductance value can be formed.

  As a technique for integrating a plurality of inductors in a small size, a technique in which another inductor is wound inside one inductor has been proposed (see, for example, Non-Patent Document 2). FIG. 11 is an explanatory diagram showing a conventional technology for miniaturizing an inductor. In the example of FIG. 11A, the inductor L1 is formed inside the inductor L2, and the inductor L3 is further formed inside thereof. Thereby, these three inductors L1, L2, L3 can be formed in the same region.

Akira Tanabe et al., “A Low-Power, Small Area Quadrature LC-VCO using miniature 3D Solenoid shaped Inductor”, IEEE RFIC 2009 pp.263-266 Akira Tsuchiya et al., “Bandwidth Enhancement for High Speed Amplifier utilizing Mutually Coupled On-Chip Inductors”, IEEE ISOCC 2011 pp.36-39 S. Galal et al., “40Gb / s Amplifier and ESD Protection Circuit in 0.18um CMOS Technology”, IEEE ISSCC 2004 vol.1 pp.480-541

  Generally, in order to realize an inductor having a high inductance value, it is necessary to increase the number of turns of the inductor or increase the diameter of the inductor. However, with an on-chip solenoid inductor, it is difficult to form a small and multi-turn inductor because the number of wiring layers is limited by a semiconductor process and the wiring width is limited by an allowable current value.

  When a plurality of inductors are integrated at a high density, it is conceivable to arrange a plurality of inductors in the same region as in the prior art shown in FIGS. However, these conventional techniques have a parallel solenoid inductor structure in which the winding axis directions of the respective inductors are parallel. For this reason, for example, as shown in the equivalent circuit of FIG. 11B, a large inductive coupling is generated between the inductors, and the available cases are extremely limited. Therefore, according to these conventional techniques, it is difficult to realize a small-sized general-purpose inductor having a high inductance value, and there is a problem that it is particularly difficult to integrate a plurality of inductors in a small size.

  In addition, in an integrated circuit on a semiconductor substrate, a peaking technique using a number of inductors has been proposed as a technique for forming a broadband amplifier (for example, see Non-Patent Document 3). In order to reduce this, it is necessary to dispose them at a distance, and there is a problem that the chip size becomes particularly large.

  An object of the present invention is to provide a solenoid inductor that can increase the mounting efficiency of an inductor and that can obtain a higher inductance value with a constant occupation area.

In order to achieve such an object, an orthogonal solenoid inductor according to the present invention is formed in a three-dimensional spiral using a plurality of metal wiring layers stacked via an insulating layer in a semiconductor substrate. First and second inductors comprising windings are formed, the first inductor is formed with a first direction as a winding axis, and the second inductor is a second orthogonal to the first direction. The direction of 2 is used as a winding axis , and its own winding is formed to circulate around the partial winding of the first inductor .

  Also, in one configuration example of the orthogonal solenoid inductor according to the present invention, the first inductor has the first direction formed in a direction perpendicular to the substrate plane of the semiconductor substrate as a winding axis, and the second inductor The inductor has a winding axis in the second direction, which is a direction parallel to the substrate plane.

  Also, in one configuration example of the orthogonal solenoid inductor according to the present invention, the first inductor has the first direction formed in a direction parallel to the substrate plane of the semiconductor substrate as a winding axis, and the second inductor The inductor has a winding axis in the second direction that is parallel to the substrate plane and is perpendicular to the first direction.

  Also, one configuration example of the orthogonal solenoid inductor according to the present invention is such that the second inductor is electrically connected in series with the first inductor.

  In addition, one configuration example of the orthogonal solenoid inductor according to the present invention includes a winding formed in a three-dimensional spiral using the metal wiring layer, and the first direction or the second direction. A third inductor formed with a third direction orthogonal to the winding axis as a winding axis, and the third inductor is partially or entirely disposed within a region where the first inductor is formed. It is what has been.

  In one configuration example of the orthogonal solenoid inductor according to the present invention, the third inductor is electrically connected in series with the first and second inductors.

  According to the present invention, since the two inductors are arranged with their winding axis directions orthogonal to each other, the plurality of inductors in which the windings are formed in the same axis direction as in the prior art are arranged in the same region. Inductive coupling can be suppressed. Therefore, the mounting efficiency of the inductor can be increased, and a higher inductance value can be obtained with a constant occupation area.

It is explanatory drawing which shows the structure of the orthogonal solenoid inductor concerning 1st Embodiment. It is a graph which shows the frequency characteristic of the inductive coupling member k regarding the orthogonal type solenoid inductor concerning 1st Embodiment. It is an equivalent circuit of the solenoid inductor used in the simulation. It is explanatory drawing which shows the structure of the orthogonal type | mold solenoid inductor concerning 1st Embodiment used by simulation. It is explanatory drawing which shows the structure of the parallel type solenoid inductor concerning the prior art used by simulation. It is explanatory drawing which shows the structure which shows the orthogonal type | mold solenoid inductor concerning 2nd Embodiment. It is explanatory drawing which shows the structure which shows the orthogonal type | mold solenoid inductor concerning 3rd Embodiment. It is explanatory drawing which shows the structure which shows the orthogonal type | mold solenoid inductor concerning 4th Embodiment. It is explanatory drawing which shows the structure which shows the orthogonal type | mold solenoid inductor concerning 5th Embodiment. It is an external view which shows the structure of the conventional solenoid inductor. It is explanatory drawing which shows the miniaturization integration technique of the conventional inductor.

Next, embodiments of the present invention will be described with reference to the drawings.
[First Embodiment]
First, an orthogonal solenoid inductor 10 according to a first embodiment of the present invention will be described with reference to FIG. FIG. 1 is an explanatory diagram illustrating a configuration of the orthogonal solenoid inductor according to the first embodiment. In the following, the stacking direction of the semiconductor substrate on which the orthogonal solenoid inductor 10 is formed is defined as the Z direction, and the two directions along the substrate plane and orthogonal to each other are defined as the X direction and the Y direction.

  The orthogonal solenoid inductor 10 includes two inductors L1 and L2 formed of windings formed in a three-dimensional spiral using a plurality of metal wiring layers stacked via an insulating layer in the semiconductor substrate 1. An on-chip solenoid inductor provided.

  In such an orthogonal solenoid inductor 10 having a plurality of inductors, a magnetic field interferes between windings of the inductors to generate inductive coupling, which causes crosstalk. Here, the degree of magnetic field interference between intersecting windings depends greatly on the crossing angle between the windings rather than the distance between the windings. In this case, magnetic field interference is extremely small between the windings orthogonal to each other. Become. In the present embodiment, paying attention to the relationship between the intersecting angle between intersecting windings and the degree of magnetic field interference, the two inductors L1 and L2 are arranged with their winding axis directions orthogonal to each other. It is a thing.

  Specifically, among these inductors L1 and L2, with respect to the inductor L1 (first inductor), a winding is formed with the Z direction (first direction) as a winding axis, and about the inductor L2 (second inductor) Is a winding formed with the Y direction (second direction) orthogonal to the Z direction as the winding axis. Further, a part or all of the inductor L2 is arranged in a region where the inductor L1 is formed. Specifically, as shown in FIG. 1, an inductor L2 is arranged inside the winding of the inductor L1. Thereby, inductive coupling can be suppressed rather than arranging a plurality of inductors having windings formed in the same axial direction in the same region as in the prior art.

  FIG. 2 is a graph showing frequency characteristics of the inductive coupling coefficient k regarding the orthogonal solenoid inductor according to the first embodiment. FIG. 3 is an equivalent circuit of the solenoid inductor used in the simulation. FIG. 4 is an explanatory diagram showing the configuration of the orthogonal solenoid inductor according to the first embodiment used in the simulation. FIG. 5 is an explanatory diagram showing a configuration of a parallel solenoid inductor according to the prior art used in the simulation.

  Here, the frequency characteristic (Hyb) of the orthogonal solenoid inductor 10 according to the present embodiment and the related art obtained by simulation using a three-dimensional electromagnetic field analysis tool in the frequency range where the signal frequency is 20 GHz or less. The frequency characteristics (Cx) of the parallel solenoid inductor (FIG. 10) are compared.

  As shown in FIG. 4, the orthogonal solenoid inductor 10 according to the present embodiment used in the simulation includes a vertical solenoid inductor L1 formed with the Z direction perpendicular to the substrate plane as the winding axis direction, and a Y parallel to the substrate plane. A horizontal solenoid inductor formed with the direction as the winding axis direction is disposed in the same region so as to overlap in the Z direction. According to this structure, since the winding axis directions of the inductors L1 and L2 are orthogonal to each other, inductive coupling hardly occurs even when the two inductors L1 and L2 are arranged in the same region. Therefore, the two inductors L1 and L2 that are magnetically independent can be integrated in a small size. Although the winding direction of the inductor L2 is the X direction and is different from the Y direction of the inductor L2 in FIG. 1, there is no influence due to the difference in the winding direction on the electromagnetic characteristics.

  On the other hand, the parallel solenoid inductor according to the prior art used in the simulation is perpendicular to the substrate plane inside the vertical solenoid inductor L1 formed with the Z direction perpendicular to the substrate plane as the winding axis direction, as shown in FIG. A vertical solenoid inductor L2 having an inductor diameter smaller than L1 and having the Z direction as the winding axis direction is disposed. According to this structure, since the winding axis directions of the inductors L1 and L2 are parallel to each other, inductive coupling is likely to occur when the two inductors L1 and L2 are arranged in the same region. Therefore, it is difficult to integrate two inductors L1 and L2 that are magnetically independent in a small size.

As shown in FIG. 4 and FIG. 5, since the inductor diameters of the two inductors L1 and L2 are different from each other, they have individual inductive coupling coefficients k1 and k2, respectively.
As shown in FIG. 2, when the conventional technique is used, the inductive coupling coefficient k is as large as about 0.48 to 0.62, whereas when this embodiment is used, k≈0. The value is about 02 to 0.03, which is about 20 times smaller. Therefore, it can be seen that by using this embodiment, two inductors with very small inductive coupling can be arranged in the same region.

[Effect of the first embodiment]
As described above, in the present embodiment, of the two inductors L1 and L2, the inductor L1 forms a winding with the first direction as the winding axis, and the inductor L2 is orthogonal to the first direction. The winding is formed with the direction of 2 as the winding axis. Further, a part or all of the inductor L2 is arranged in a region where the inductor L1 is formed.

More specifically, the inductor L1 has a winding direction in the Z direction that is perpendicular to the substrate plane of the semiconductor substrate 1, and the inductor L2 has a winding direction in the Y direction that is parallel to the substrate plane. is there.
Thereby, inductive coupling can be suppressed rather than arranging a plurality of inductors having windings formed in the same axial direction in the same region as in the prior art. Therefore, it is possible to provide a solenoid inductor that can increase the mounting efficiency of the inductor and can obtain a higher inductance value with a constant occupation area.

  Further, in this embodiment, it can be used for an integrated circuit using many inductors as described in Non-Patent Document 3, and two inductors can be integrated in the same region, and the size is reduced to about 1/2. it can.

  Further, in an on-chip inductor, a metal layer generally has a hierarchical structure, and an inductor with a free winding axis cannot be formed. According to the present embodiment, the inductor L1 having a winding axis in the Y direction perpendicular to the substrate plane of the semiconductor substrate and the inductor L2 wound in the Y direction parallel to the substrate plane are used. Even if the inductors are arranged in the same region, a plurality of inductors can be integrated while reducing inductive coupling.

  Further, in this embodiment, as shown in FIG. 1, a square type inductor L1 wound about 3.75 times in the Z direction and a square type inductor L2 wound about 2.75 times in the Y direction are used. However, it is sufficient that the axial directions of the two inductors are orthogonal to each other, and a combination of the Y-axis inductor and the X-axis inductor as shown in FIG. Is possible. Further, the number of turns and the shape of each inductor are not limited to this.

  In the present embodiment, the two inductors L1 and L2 may be electrically connected in series. As a result, it is possible to realize an inductor having a high inductance value of approximately L1 + L2 with an occupied area for forming a conventional inductor, and it is also possible to realize a small inductor and a high inductance value.

[Second Embodiment]
Next, an orthogonal solenoid inductor 10 according to a second embodiment of the present invention will be described with reference to FIG. FIG. 6 is an explanatory diagram showing a configuration showing an orthogonal solenoid inductor according to the second embodiment.

  In the first embodiment, the case where the winding axis direction of the inductor L1 is the Z direction and the winding axis direction of the inductor L2 is the Y direction has been described as an example, but the two orthogonal winding axes are limited to these. The direction may be parallel to the substrate plane of the semiconductor substrate and orthogonal to each other.

  That is, in the present embodiment, the inductor L1 has the winding direction in the X direction that is parallel to the substrate plane of the semiconductor substrate, and the inductor L2 is the Y direction that is parallel to the substrate plane and perpendicular to the X direction. Is the winding axis. Further, a part or all of the inductor L2 is arranged in a region where the inductor L1 is formed. Specifically, as shown in FIG. 6, an inductor L2 is arranged inside the winding of the inductor L1.

  As a result, as in the first embodiment, inductive coupling can be suppressed as compared to the case where a plurality of inductors having windings formed in the same axial direction as in the prior art are arranged in the same region. Therefore, it is possible to provide a solenoid inductor that can obtain a higher inductance value without increasing the occupation area.

[Third Embodiment]
Next, an orthogonal solenoid inductor 10 according to a third embodiment of the present invention will be described with reference to FIG. FIG. 7 is an explanatory diagram showing a configuration showing an orthogonal type solenoid inductor according to a third embodiment.

  In the first and second embodiments, the case where the inductor L2 is arranged inside the winding of the inductor L1 has been described. In the present embodiment, a case will be described in which the winding of the inductor L2 is formed so as to go around the partial winding of the inductor L1.

  That is, in the present embodiment, the inductor L1 (first inductor) forms a winding with the Z direction (first direction) as the winding axis, and the inductor L2 (second inductor) is the Z direction. A winding is formed with a perpendicular Y direction (second direction) as a winding axis. In addition to this, the winding of the inductor L2 is formed to circulate around the partial winding of the inductor L1.

  Thereby, compared with the case where the inductor L2 is arranged inside the winding of the inductor L1, the inductor diameter of the inductor L2 is not restricted by the inductor diameter of the inductor L1. Moreover, since it becomes easy to ensure the distance between the windings of the inductors L1 and L2, capacitive coupling between the inductors L1 and L2 can be reduced. For this reason, the size of the inductor L2 can be freely designed, and the orthogonal solenoid inductor 10 having performance according to a given condition can be manufactured more flexibly.

[Fourth Embodiment]
Next, an orthogonal solenoid inductor 10 according to a fourth embodiment of the present invention will be described with reference to FIG. FIG. 8 is an explanatory diagram showing a configuration showing an orthogonal type solenoid inductor according to a fourth embodiment.

  In the first to third embodiments, the case where two inductors L1 and L2 are used has been described as an example, but the number of inductors is not limited to this. In the present embodiment, a case where three inductors L1, L2, and L3 are used will be described as an example based on the third embodiment.

  That is, in the present embodiment, a winding is formed around the Z direction (first direction) for the inductor L1 (first inductor), and the Z direction for the inductor L2 (second inductor). A winding is formed with the Y direction (second direction) orthogonal to the winding axis, and the inductor L3 (third inductor) is wound with the Y direction (second direction) orthogonal to the Z direction as the winding axis. Is formed.

In addition, a part or all of the inductor L3 is arranged in a region where the inductor L1 is formed. Specifically, like the inductor L2, the winding of the inductor L3 is formed to circulate around the partial winding of the inductor L1.
Accordingly, the orthogonal solenoid inductor 10 can be configured using three or more inductors, and the on-chip inductor can be reduced in size and integrated.

  At this time, in the configuration example of FIG. 8, the inductors L <b> 2 and L <b> 3 are parallel to each other in the winding axis direction. Further, as shown in FIG. 8, if the inductors L2 and L3 are arranged at positions facing each other with the inductor L1 therebetween, a distance can be provided between them, and inductive coupling between the inductors L2 and L3 is suppressed. be able to.

[Fifth Embodiment]
Next, an orthogonal solenoid inductor 10 according to a fifth embodiment of the present invention will be described with reference to FIG. FIG. 9 is an explanatory diagram illustrating a configuration of an orthogonal solenoid inductor according to a fifth embodiment.

  In the present embodiment, a case where three inductors L1, L2, and L3 are arranged in the same region as shown in FIG. 9 will be described based on the first embodiment.

That is, in the present embodiment, a winding is formed around the Z direction (first direction) for the inductor L1 (first inductor), and the Z direction for the inductor L2 (second inductor). Winding is formed with the Y direction (second direction) orthogonal to the winding axis, and the inductor L3 (third inductor) is set with the Z direction and X direction (third direction) orthogonal to the Y direction as the winding axis. A winding is formed.
As shown in FIG. 9, the inductor L1 is arranged inside the winding of the inductor L3, and the inductor L2 is arranged inside the winding of the inductor L1.

  Thereby, the three inductors L1, L2, and L3 having winding axes orthogonal to each other can be disposed in the same region of the semiconductor substrate 1. Therefore, a larger number of inductors can be integrated in a small size while suppressing inductive coupling.

  Further, by electrically connecting these three inductors L1, L2, and L3 in series, it is possible to realize an inductor having a high inductance value of approximately L1 + L2 + L3 with an occupied area for forming one conventional inductance value. In addition, one inductor can be realized in a small size and a high inductance value.

  In FIG. 9, the square inductor L1 wound about twice in the X-axis direction, the square inductor L2 wound about 3.75 times in the Z-axis direction, and about 2.75 turns in the Y-axis direction. Although an example of an orthogonal type solenoid inductor using the square type inductor L3 is shown, it is only necessary that the axial directions of the three inductors are orthogonal to each other, and the number of turns and the shape of each inductor are not limited to this.

  In the present embodiment, the configuration in which the inductor L1 is arranged inside the winding of the inductor L3 and the inductor L3 is arranged inside the winding of the L2 has been described as an example. However, the arrangement relationship of the inductor is not limited thereto. is not. For example, the inductors shown in FIG. 7 may be arranged so as to share only a partial region.

  Further, FIG. 9 shows an example in which three inductors are arranged, but as shown in FIG. 8 described above, the winding of an arbitrary inductor L3 circulates around a part of windings of other inductors. A configuration in which four or more inductors are arranged by forming and arranging a plurality of them while maintaining a distance between arbitrary inductors as necessary can be considered.

[Extended embodiment]
The present invention has been described above with reference to the embodiments, but the present invention is not limited to the above embodiments. Various changes that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the present invention. In addition, each embodiment can be implemented in any combination within a consistent range.

  DESCRIPTION OF SYMBOLS 1 ... Semiconductor substrate, 10 ... Orthogonal solenoid inductor, L1, L2, L3 ... Inductor.

Claims (6)

Using a plurality of metal wiring layers stacked via an insulating layer of a semiconductor substrate, and comprising first and second inductors comprising three-dimensionally formed windings,
The first inductor is formed with a first direction as a winding axis,
The second inductor has a second direction orthogonal to the first direction as a winding axis , and is formed such that its own winding circulates around a part of the winding of the first inductor. An orthogonal solenoid inductor characterized by The orthogonal solenoid inductor according to claim 1 ,
The first inductor has a winding axis in the first direction, which is a direction perpendicular to the substrate plane of the semiconductor substrate,
The quadrature solenoid inductor, wherein the second inductor has a winding axis in the second direction, which is a direction parallel to the plane of the substrate. The orthogonal solenoid inductor according to claim 1 ,
The first inductor has a winding axis in the first direction, which is a direction parallel to the substrate plane of the semiconductor substrate,
The quadrature solenoid inductor, wherein the second inductor has a winding axis in the second direction that is parallel to the substrate plane and perpendicular to the first direction. In the orthogonal type solenoid inductor according to any one of claims 1 to 3 ,
The quadrature solenoid inductor, wherein the second inductor is electrically connected in series with the first inductor. In the orthogonal type solenoid inductor according to any one of claims 1 to 3 ,
A third wire formed of a winding formed in a three-dimensional spiral using the metal wiring layer and having a third direction orthogonal to the first direction or the second direction as a winding axis. Further comprising an inductor;
A part or all of the third inductor is disposed in a region where the first inductor is formed. An orthogonal solenoid inductor, wherein: The orthogonal solenoid inductor according to claim 5 ,
The orthogonal solenoid inductor, wherein the third inductor is electrically connected in series with the first and second inductors.

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