CN113066645B

CN113066645B - Asymmetric spiral inductor

Info

Publication number: CN113066645B
Application number: CN201911294586.6A
Authority: CN
Inventors: 颜孝璁; 陈家源
Original assignee: Realtek Semiconductor Corp
Current assignee: Realtek Semiconductor Corp
Priority date: 2019-12-16
Filing date: 2019-12-16
Publication date: 2022-09-13
Anticipated expiration: 2039-12-16
Also published as: CN113066645A

Abstract

The invention relates to an asymmetric spiral inductor which comprises a first winding, a second winding and a third winding. The first winding has a first end and a second end and is fabricated on the ultra-thick metal layer of the semiconductor structure. The second winding is provided with a third end point and a fourth end point, is manufactured on a rewiring layer of the semiconductor structure and has a first maximum routing width. The third winding has a fifth end point and a sixth end point, is manufactured on the ultra-thick metal layer of the semiconductor structure, and has a second maximum routing width smaller than the first maximum routing width. The second end point and the third end point are connected through the first penetrating structure, the fourth end point and the fifth end point are connected through the second penetrating structure, and the first end point and the sixth end point form two end points of the asymmetric spiral inductor.

Description

Asymmetric spiral inductor

Technical Field

The present invention relates to integrated inductors, and more particularly, to an asymmetric spiral integrated inductor.

Background

Fig. 1A and 1B show a conventional asymmetric spiral inductor (asymmetric spiral inductor) and a conventional symmetric spiral inductor (symmetric spiral inductor), respectively. The asymmetric spiral inductor 100 and the symmetric spiral inductor 200 are planar structures. The symmetrical spiral inductor 200 is mainly composed of conductor segments located in two conductor layers (shown in gray and black, respectively). The conductor segments located in different conductor layers are connected by a through structure 105, and the through structure 105 is, for example, a via (via) structure or a via array (via array) in a semiconductor process. Generally, the symmetrical spiral inductor 200 is symmetrical in structure, so it is suitable for differential (differential) signals, and the asymmetrical spiral inductor 100 is suitable for single-ended (single-ended) signals.

One of the methods to increase the inductance of the asymmetric spiral inductor 100 and the symmetric spiral inductor 200 is to increase the number of coils. The increase in the number of coils not only increases the area of the asymmetric spiral inductor 100 and the area of the symmetric spiral inductor 200, but also increases the parasitic series resistance (parasitic series resistance) and the parasitic capacitance (parasitic capacitance). The high parasitic series resistance and parasitic capacitance cause the self-oscillation frequency (self-oscillation frequency) and the quality factor (quality factor) Q of the asymmetric spiral inductor 100 and the symmetric spiral inductor 200 to decrease. In addition, metal loss (metal loss) and substrate loss (substrate loss) are also important factors affecting the quality factor Q. Metal loss is due to the resistance of the metal itself. The substrate loss is caused by two types, one is from the fact that when the inductor acts, a time-varying electrical displacement (displacement) is generated between the metal coil of the inductor and the substrate, and the displacement current (displacement current) is generated between the metal coil and the substrate and penetrates into the substrate with low impedance to form energy loss. The displacement current is related to the area of the inductance coil, and the larger the area is, the larger the displacement current is. Another is that the time-varying electromagnetic field from the inductor penetrates the dielectric to generate a magnetic induced current (inductor) on the substrate, which is opposite to the direction of the inductor current and causes energy loss.

When the inductor operates at a low frequency, the current in the metal coil is uniformly distributed, and the metal loss is from the series resistance of the metal coil at the low frequency. When the inductor operates at high frequency, the metal coil closer to the inner ring generates stronger magnetic field; the strong magnetic field induces eddy currents (eddy current) in the inner coil of the metal coil. The eddy current causes uneven current distribution, so that most of the current is pushed to the surface of the metal coil; this phenomenon is called skin effect. Under the skin effect, the cross section of the metal through which the current flows becomes smaller, so that a larger resistance is felt, and the quality factor Q is reduced.

Therefore, how to improve the quality factor Q and the inductance value of the inductor without increasing the area of the inductor is an important issue in the field.

Disclosure of Invention

In view of the shortcomings of the prior art, an object of the present invention is to provide an asymmetric spiral inductor.

The invention discloses an asymmetric spiral inductor which comprises a first winding, a second winding and a third winding. The first winding has a first terminal and a second terminal, and is fabricated on the ultra-thick metal layer of the semiconductor structure. The second winding has a third end point and a fourth end point, is manufactured on a redistribution layer of the semiconductor structure and has a first maximum routing width. The third winding has a fifth end point and a sixth end point, is manufactured on the ultra-thick metal layer of the semiconductor structure, and has a second maximum routing width smaller than the first maximum routing width. The second end point and the third end point are connected through the first penetrating structure, the fourth end point and the fifth end point are connected through the second penetrating structure, and the first end point and the sixth end point form two end points of the asymmetric spiral inductor.

The invention also discloses an asymmetric spiral inductor which comprises a spiral coil, a first wire and a second wire. The spiral coil has a first end and a second end, and is fabricated on the first conductive layer of the semiconductor structure. The first wire has a third end point and a fourth end point and is manufactured on a second conductor layer of the semiconductor structure, wherein the first conductor layer is not equal to the second conductor layer, and the length of the first wire is less than one turn of the spiral coil. The second wire has a fifth end and a sixth end and is fabricated on the first conductive layer of the semiconductor structure. The second end point and the third end point are connected through the first penetrating structure, the fourth end point and the fifth end point are connected through the second penetrating structure, and the first end point and the sixth end point form two end points of the asymmetric spiral inductor.

Compared with the prior art, the asymmetric spiral inductor is actually operated on two different conductor layers in the semiconductor structure, and the inductance value of the asymmetric spiral inductor can be improved under the condition of not increasing the area of the inductor, so that the quality factor Q is improved

The features, practical operations and effects of the present invention will be described in detail with reference to the drawings.

Drawings

Fig. 1A shows a conventional asymmetric spiral inductor;

FIG. 1B shows a conventional symmetrical spiral inductor;

fig. 2 shows an asymmetric spiral inductor with four turns.

Fig. 3 is a four-turn asymmetric spiral inductor.

FIG. 4A is winding 410 of FIG. 3;

FIG. 4B is the winding 420 of FIG. 3;

FIG. 4C is the winding 430 of FIG. 3;

FIG. 5 is one embodiment of cross-section A-A of FIG. 3;

FIG. 6 is another embodiment of cross-section A-A of FIG. 3;

FIG. 7 is another embodiment of cross-section A-A of FIG. 3;

FIG. 8A is a diagram of another embodiment of an asymmetric spiral inductor according to the present invention;

FIG. 8B is cross-section B-B of FIG. 8A;

fig. 9A is a schematic diagram of an asymmetric spiral inductor according to another embodiment of the present invention;

FIG. 9B is cross-section C-C of FIG. 9A;

FIG. 10A is a diagram of another embodiment of an asymmetric spiral inductor according to the present invention;

FIG. 10B is cross-section D-D of FIG. 10A; and

fig. 11 shows quality factors Q of the asymmetric spiral inductor 300 and the asymmetric spiral inductor 400.

Detailed Description

In the following description, the technical terms refer to the common terms in the technical field, and some terms are explained or defined in the specification, and the explanation of the some terms is based on the explanation or the definition in the specification.

The present disclosure includes an asymmetric spiral inductor. Since some of the components included in the asymmetric spiral inductor of the present invention may be known components alone, the following description will omit details of the known components without affecting the full disclosure and feasibility of the present invention.

Fig. 2 and fig. 3 each show a top view or a bottom view of a four-turn asymmetric spiral inductor, where the asymmetric spiral inductor 300 of fig. 2 is actually operated on the first conductive layer or the second conductive layer of the semiconductor structure, and the asymmetric spiral inductor 400 of fig. 3 is actually operated on the first conductive layer and the second conductive layer of the semiconductor structure. The first conductive layer and the second conductive layer may be any two different conductive layers of the semiconductor structure, for example, the first conductive layer may be one of an ultra-thick metal (UTM) layer and a redistribution layer (RDL), and the second conductive layer is the other.

As shown in fig. 2, the asymmetric spiral inductor 300 is formed by a single winding 310. In other words, the winding 310 itself is the asymmetric spiral inductor 300. The winding 310 may be considered to be comprised of a single trace.

As shown in fig. 3, the asymmetric spiral inductor 400 is composed of three windings: winding 410, winding 420, and winding 430.

Windings

410 and 430 are actually operated at a first conductor layer, while winding 420 is actually operated at a second conductor layer.

Windings

410, 420, and 430 are connected by through structure 401 and through structure 402. More specifically, through structure 401 connects one of the ends of winding 420 with winding 410, and through structure 402 connects the other end of winding 420 with winding 430. The winding 420 extends along the edge of the asymmetric spiral inductor 400 or the winding 430, and thus, the shape of the winding 420 is similar to the profile of the asymmetric spiral inductor 400 and/or the portion of the winding 430.

As shown in fig. 2 and 3, the asymmetric spiral inductor 300 and the asymmetric spiral inductor 400 are both 4-turn spiral inductors, and the difference is that all traces of the asymmetric spiral inductor 300 are actually operated in the same conductive layer, while most traces of the asymmetric spiral inductor 400 are actually operated in the first conductive layer, but some traces (i.e., the winding 420) are actually operated in the second conductive layer. In other words, the asymmetric spiral inductor 300 has a planar structure, and the asymmetric spiral inductor 400 has a three-dimensional structure. Therefore, under the premise of having the same number of turns and outer diameter D1 (i.e. under the premise of substantially the same area of the inductor), the inner diameter D3 of the asymmetric spiral inductor 400 is larger than the inner diameter D2 of the asymmetric spiral inductor 300, so that the quality factor Q of the asymmetric spiral inductor 400 is higher than that of the asymmetric spiral inductor 300.

Fig. 4A, 4B and 4C show winding 410, winding 420 and winding 430, respectively. Winding 410 is a trace or coil having a length of approximately one-half turn of asymmetric spiral inductor 400. Winding 420 is a trace or coil having a length of approximately one turn of asymmetric spiral inductor 400. Winding 430 forms an asymmetric helical coil. The two terminals of winding 410 are terminal 411 and terminal 412, the two terminals of winding 420 are terminal 421 and terminal 422, and the two terminals of winding 430 are terminal 431 and terminal 432. Terminal 411 is one terminal of asymmetric spiral inductor 400, terminal 412 is connected to terminal 421 through via 401, terminal 422 is connected to terminal 431 through via 402, and terminal 432 is the other terminal of asymmetric spiral inductor 400. In this embodiment, the length of the trace of winding 410 is about half of the turn of asymmetric spiral inductor 400 or winding 430, but may be longer (e.g., 3/4 turns, 1 turn, or more) or shorter (e.g., 1/4 turns or less). In this embodiment, the length of the trace of winding 420 is about 1 turn of asymmetric spiral inductor 400 or winding 430, but may be longer (e.g., 1.5 or more turns) or shorter (e.g., less than 1 turn). In this embodiment, the winding 430 has a multi-turn structure, preferably 1 turn or more.

Fig. 5 shows an embodiment of cross-section a-a of fig. 3. In this embodiment, the widths of the traces of winding 410, winding 420 and winding 430 are all W1. In the left half of the figure, part of the trace of the winding 420 is completely overlapped or partially overlapped with part of the trace of the winding 430, and in the right half of the figure, part of the trace of the winding 420 is partially overlapped with part of the trace of the winding 410 and partially overlapped with part of the trace of the winding 430. Winding 420 and adjacent winding 410 and/or winding 430 may generate mutual inductance Lm.

Fig. 6 shows another embodiment of the cross-section a-a of fig. 3. In this embodiment, the widths of the traces of the

windings

410 and 430 are both W1 (in other words, the maximum trace widths of the

windings

410 and 430 are W1), and the maximum trace width of the winding 420 is W2 or W3. When W2 is equal to W3, the trace of winding 420 has a uniform width; when W2 is not equal to W3, the trace of winding 420 has a non-uniform width. Compared to fig. 5, because the overlap between winding 420 and winding 410 and/or winding 430 becomes larger (i.e., W2 and/or W3 is greater than W1), the mutual inductance Lm' between winding 420 and winding 410 and/or winding 430 is greater than the mutual inductance Lm of the embodiment of fig. 5. In other words, the inductor of fig. 6 has a higher inductance value than the embodiment of fig. 5.

Generally, the unit resistance of the redistribution layer is greater than that of the ultra-thick metal layer, so when the first conductor layer is the ultra-thick metal layer and the second conductor layer is the redistribution layer, the larger width W2 and/or W3 (compared to W1) can make the winding 420 have a lower resistance. Therefore, although the actual operation is performed on the conductor layer having a large unit resistance value, the resistance value of the entire winding 420 may not be increased (compared to the resistance value when the actual operation is performed on the ultra-thick metal layer and the width is W1) because the width of the trace is increased.

Fig. 7 shows another embodiment of the cross-section a-a of fig. 3. Of the traces of the winding 430, the traces that overlap or partially overlap the winding 420 may have a greater width (i.e., W4> W1) than traces that do not overlap the winding 420, such that the mutual inductance Lm "between the winding 420 and the winding 430 is greater than the mutual inductance Lm' of the embodiment of fig. 6. In some embodiments,

windings

420 and 430 may overlap by more than one turn, possibly more than two turns. In other words, the inductor of fig. 7 has a higher inductance value than the embodiment of fig. 6. The outer diameter of the inductor in fig. 7 is equal to the outer diameter of the inductor in fig. 6 (both D1), but because the trace of the partial winding 430 in fig. 7 is wider, the inner diameter D4 of the inductor in fig. 7 is smaller than the inner diameter D3 of the inductor in fig. 6. In the embodiment of fig. 7, the width W5 of the partial trace of the winding 420 is greater than the sum of the width W4 of the partial trace of the winding 430 and the spacing D5 between two adjacent turns.

Fig. 8A is a top or bottom view of another embodiment of the asymmetric spiral inductor of the present invention, and fig. 8B shows a cross-section B-B of fig. 8A. Asymmetric spiral inductor 800 has a 4-turn structure similar to asymmetric spiral inductor 400, and includes a winding 810, a winding 820, and a winding 830.

Windings

810 and 830 actually operate in a first conductor layer, while winding 820 actually operates in a second conductor layer. Winding 810, winding 820, and winding 830 are connected by through structure 801 and through structure 802. More specifically, through structure 801 connects one of the ends of winding 820 to winding 810, and through structure 802 connects the other end of winding 820 to winding 830. Winding 820 extends along the edge of asymmetric spiral inductor 800 or winding 830, and thus, the shape of winding 820 is similar to the profile of asymmetric spiral inductor 800 and/or portions of winding 830. Terminal 811 and terminal 832 are two terminals of the asymmetric spiral inductor 800.

As shown in fig. 8A and 8B, a portion of winding 820 overlaps one of the turns (the outermost turn in this embodiment) of winding 830. Mutual inductance Lm is generated between winding 820 and adjacent winding 830. Referring to fig. 5 to 7, widths of the

windings

810, 820 and 830 are not limited to the example shown in fig. 8B.

Fig. 9A is a top or bottom view of another embodiment of an asymmetric spiral inductor of the present invention, and fig. 9B shows cross-section C-C of fig. 9A. Asymmetric spiral inductor 900 has a 4-turn structure similar to asymmetric spiral inductor 400 and includes

windings

910, 920, and 930.

Windings

910 and 920 are physically operated in a first conductor layer, while winding 930 is physically operated in a second conductor layer.

Windings

910, 920, and 930 are connected by through structure 901 and through structure 902. More specifically, through structure 901 connects one of the end points of winding 920 to winding 910, while through structure 902 connects the other end point of winding 920 to winding 930. The winding 920 extends along the edge of the asymmetric spiral inductor 900 or the winding 930, and thus the shape of the winding 920 is similar to the profile of the asymmetric spiral inductor 900 and/or the portion of the winding 930. Terminal 911 and terminal 932 are two terminals of the asymmetric spiral inductor 900.

As shown in fig. 9A and 9B, the winding 920 does not overlap with the winding 910 and the winding 930. The winding 920 is located at the outermost turn of the asymmetric spiral inductor 900, and the length of the trace of the winding 920 is about half of the turn of the asymmetric spiral inductor 900 or the winding 930. Referring to fig. 5 to fig. 7, the widths of the traces of the

windings

910, 920 and 930 are not limited to the example shown in fig. 9B.

Fig. 10A is a top view or bottom view of another embodiment of the asymmetric spiral inductor of the present invention, and fig. 10B shows cross-section D-D of fig. 10A. The asymmetric spiral inductor 1000 has a 4-turn structure similar to the asymmetric spiral inductor 400, and includes a winding 1010, a winding 1020, a winding 1030, and a winding 1040.

Windings

1020 and 1040 are actually operated at a first conductor layer, while

windings

1010 and 1030 are actually operated at a second conductor layer.

Windings

1010, 1020, 1030, and 1040 are connected by through structure 1001, through structure 1002, and through structure 1003. The

windings

1010 and 1030 extend along the edges of the asymmetric spiral inductor 1000 or the windings 1040, and thus the shapes of the

windings

1010 and 1030 are similar to the contours of portions of the asymmetric spiral inductor 1000 and/or the windings 1040. The

terminals

1011 and 1042 are two terminals of the asymmetric spiral inductor 900.

As shown in fig. 10A and 10B, the

windings

1010 and 1030 do not overlap with the winding 1040. The

windings

1010 and 1030 are located at the outermost turn of the asymmetric spiral inductor 1000, and the length of the trace of the

windings

1010 and 1030 is about half of the turn of the asymmetric spiral inductor 1000 or the winding 1040. Referring to fig. 5 to fig. 7, widths of the

windings

1010, 1020, 1030 and 1040 are not limited to the example shown in fig. 10B.

Fig. 11 shows quality factors Q of the asymmetric spiral inductor 300 and the asymmetric spiral inductor 400. Curve 1110 represents the Q of asymmetric spiral inductor 300, and curve 1120 represents the Q of asymmetric spiral inductor 400. Compared with the asymmetric spiral inductor 300, the asymmetric spiral inductor 400 has a structure that can improve the quality factor Q of the inductor.

Although the coil of the above embodiments is illustrated as an octagon, the invention is not limited thereto, and the inductors may be other polygonal or circular. The inductor of the present invention is not limited to 4 turns.

In summary, the inductance of the asymmetric spiral inductor can be improved without increasing the area of the inductor, thereby improving the quality factor Q.

It should be noted that the shapes, sizes, proportions and the like of the components in the above-mentioned figures are only schematic and are not intended to limit the present invention, which is understood by those skilled in the art.

Although the embodiments of the present invention have been described above, these embodiments are not intended to limit the present invention, and those skilled in the art can make variations on the technical features of the present invention according to the explicit or implicit contents of the present invention, and all such variations may fall within the scope of the patent protection sought by the present invention.

[ notation ] to show

100. 300, 400, 800, 900, 1000 asymmetric spiral inductor

200 symmetrical spiral inductor

105. 401, 402, 801, 802, 901, 902, 1001, 1002, 1003 penetration structure

310. 410, 420, 430, 810, 820, 830, 910, 920, 930, 1010, 1020, 1030, 1040 windings

411. 412, 421, 422, 431, 432, 811, 832, 911, 932, 1011, 1042 endpoints

D1 outer diameter

D2, D3, D4 inner diameter

Interval D5

W1, W2, W3, W4 and W5 widths

Lm, Lm' mutual inductance

1110. 1120 curve.

Claims

1. An asymmetric spiral inductor comprising:

a first winding having a first end and a second end and formed on an ultra-thick metal layer of a semiconductor structure;

the second winding is provided with a third end point and a fourth end point, is manufactured on a rewiring layer of the semiconductor structure and has a first maximum routing width; and

a third winding, having a fifth end point and a sixth end point, fabricated on the ultra-thick metal layer of the semiconductor structure, and having a second maximum trace width smaller than the first maximum trace width;

the second end point and the third end point are connected through a first through structure, the fourth end point and the fifth end point are connected through a second through structure, and the first end point and the sixth end point form two end points of the asymmetric spiral inductor;

the first maximum trace width is greater than the sum of the second maximum trace width and the interval between two adjacent traces in the third winding.

2. The asymmetric helical inductor of claim 1 wherein the length of the second winding is less than one turn of the asymmetric helical inductor.

3. The asymmetric spiral inductor of claim 1 wherein a portion of the second winding extends along an edge of the third winding.

4. The asymmetric spiral inductor of claim 3 wherein a portion of the second winding overlaps a portion of the third winding.

5. The asymmetric spiral inductor of claim 3 wherein a first portion of the second winding overlaps a portion of the third winding and a second portion of the second winding overlaps a portion of the first winding and overlaps a portion of the third winding.

6. The asymmetric spiral inductor of claim 1 wherein the second winding is located at an outer ring of the asymmetric spiral inductor and does not overlap the third winding.

7. An asymmetric spiral inductor comprising:

a spiral coil having a first end and a second end and made on a first conductor layer of a semiconductor structure;

a first wire having a third end point and a fourth end point and being fabricated on a second conductor layer of the semiconductor structure, wherein the first conductor layer is not equal to the second conductor layer, and the length of the first wire is less than one turn of the spiral coil; and

a second wire having a fifth end and a sixth end and formed on the first conductor layer of the semiconductor structure;

the spiral coil has a first maximum width, the first trace has a second maximum width, the second maximum width is greater than the first maximum width, and the second maximum width is greater than the sum of the first maximum width and the interval between two adjacent coils in the spiral coil.

8. The asymmetric spiral inductor as claimed in claim 7, wherein the first conductive layer is an ultra-thick metal layer and the second conductive layer is a redistribution layer.

9. The asymmetric spiral inductor as claimed in claim 7, wherein a portion of the first trace extends along an edge of the spiral coil.