CN113539608B - Inductor and method for manufacturing the same - Google Patents

Abstract

An inductor formed on a semiconductor or insulator substrate has a two-layer structure in which the number of turns of a first layer and a second layer is smaller than one turn and partially overlapped, and the total number of turns of the two layers exceeds one turn and is smaller than two turns. The first layer between the first external connection portion and the second interlayer connection portion and the second layer between the second interlayer connection portion and the second external connection portion are connected in series, and the first layer and the second layer between the first interlayer connection portion and the second interlayer connection portion are connected in parallel.

Description

Inductor and method for manufacturing the same

Technical Field

The present invention relates to a structure of an inductor formed on a semiconductor substrate or an insulator substrate.

Background

Referring to patent publication 2007-67236 (Fushitong), hereinafter referred to as "document 1" and "US 20110133879A1 (Shanghai Hua Hong NEC electrons), hereinafter referred to as" document 2 ", a conventional spiral inductor is an electronic device widely used in semiconductor substrates, or IPD (Integrated Passive Device) on insulators and semiconductor substrates.

In IPD, particularly in applications of filters such as band-pass filters, high Q-value inductors are required, and therefore various structures have been proposed, Q-value of inductors: the quality factor of the inductor is also called as the main parameter for measuring the inductor, and refers to the ratio of the inductance presented by the inductor to the equivalent loss resistance of the inductor when the inductor works under the alternating current voltage with a certain frequency, and the higher the Q value of the inductor is, the smaller the loss is, and the higher the efficiency is.

Document 1 adopts two elliptical spiral metal ring structures with air bridges to increase the Q value of the inductor.

In recent years, the frequency used for wireless communication has moved to a higher side, and with this frequency, the value of the inductor used for a filter or the like has moved to a lower side, and it has been demanded to obtain a high Q value from the values of the inductors ranging from 0.5nH to 2 nH.

Although various structures have been recently developed to improve the Q value of a general spiral inductor, it is not suitable to obtain high Q in an inductor having a small inductance.

Disclosure of Invention

It is an object of the present invention to provide an inductor which ameliorates at least one of the disadvantages of the prior art.

The inductor of the present invention is formed on a semiconductor or insulator substrate and has a two-layer structure in which the number of turns of both the first layer and the second layer is smaller than one turn and has a portion overlapping in plan view, the total number of turns of both exceeds one turn and is smaller than two turns, the inductor has two external connection portions as a first external connection portion and a second external connection portion, respectively, the first layer and the second layer are connected by at least a first interlayer connection portion close to the first external connection portion and a second interlayer connection portion close to the second external connection portion, the first layer from the first external connection portion to the second interlayer connection portion, and the second layer from the second interlayer connection portion to the second external connection portion are connected in series, and the first layer and the second layer between the first interlayer connection portion to the second interlayer connection portion are connected in parallel and spaced apart in a vertical direction.

Preferably, the inductor of the present invention has a portion of its outer periphery and is connected in series with a single turn metal ring inside the inductor.

Preferably, the first layer and the second layer are metal rings, the outer periphery of the first layer has a portion of the inductor and the inner Zhou Chuanlian of the first layer, and the outer periphery of the second layer has a portion of the inductor and the outer periphery of the second layer has an inner Zhou Chuanlian of the second layer.

Preferably, the inductor of the present invention has a shape of a ring with a cutout, the ring being a ring shape or a polygon having four or more sides with no metal in the center.

Preferably, the inductor of the present invention has a radial deviation between the inner edge of the first layer and the inner edge of the second layer of less than 10 μm.

Preferably, in the inductor of the present invention, the second layer is an air bridge structure, and the air bridge structure includes a first interlayer connection portion, a second interlayer connection portion and/or a plurality of support columns located at the periphery of the second layer.

Preferably, the support column is formed by extending from the outer periphery of the second layer to the outer side of the inductor in a circular ring shape or a polygonal shape.

Preferably, the first layer is metal and has a thickness of 0.3-3.5 μm; the second layer is made of metal and has a thickness of 3-12 mu m, and the height of an air gap between the first layer and the second layer is 2-7.5 mu m.

Preferably, the periphery of the circular ring is 400 μm, the number of turns of the inductor is 1.75 turns, the ring width of the circular ring is 70 μm, the inductance value of the inductor is 1.8nH, the maximum quality factor is 70, the frequency corresponding to the maximum quality factor of the inductor is 6.5GHz, the cutoff frequency is above 15GHz, the number of turns of the metal ring outside the inductor and the number of turns of the metal ring inside the inductor can be the same or different, and the metal ring outside the inductor and the metal ring inside the inductor are respectively in a two-layer structure.

The method for manufacturing the inductor comprises the following steps:

a. defining a first region and a second region which are spaced from each other on a substrate, and forming a first metal layer on the first region and the second region to form a first layer positioned in the first region and a lower part of a support column positioned in the second region;

b. forming a sacrificial layer between the first layer and the lower parts of the first layer and the support columns, wherein the sacrificial layer is formed to expose the first layer from two third areas;

c. forming a second metal layer on the lower parts of the sacrificial layer and the supporting part to form an upper part covering the lower part of the supporting column, a second layer covering the sacrificial layer, and two interlayer connecting parts which are positioned in a third area and connected with the first layer and the second layer; and

d. the sacrificial layer is removed.

The invention has the beneficial effects that: by adopting this structure, the highest Q value can be obtained under the condition that the number of turns, the material, thickness, and occupied area of each turn are constant. When the inductor is applied to an inductor having an inductance of 0.5nH to 2nH, if the relationship between the first external connection portion and the second external connection portion of the inductor is determined in the IPD circuit mode, not only is the degree of freedom of arrangement limited, but also an extra wiring is required, and the characteristics of the circuit may be deteriorated. In the present invention, even if the first external connection portion and the second external connection portion are separated, the first layer and the second layer are spaced apart and connected in the vertical direction during this period, and thus a high Q value can be obtained.

Drawings

Other features and advantages of the present invention will become apparent from the following description of the embodiments with reference to the drawings, in which:

fig. 1 is a partial structural perspective view of a first embodiment of an inductor of the present invention;

FIG. 2 is a schematic view illustrating the first metal layer and the first interlayer connection overlapping the second interlayer connection of the first embodiment;

FIG. 3 is a schematic view illustrating the second metal layer and the first interlayer connection overlapping the second interlayer connection according to the first embodiment;

FIG. 4 is a schematic diagram illustrating the first and second layers of metal overlap of the first embodiment;

fig. 5 is a perspective view of the first embodiment;

FIG. 6 is a cross-sectional view taken along section line E-E of FIG. 5;

FIG. 7 is a cross-sectional view taken along section line F-F of FIG. 5;

fig. 8 is a top view of the inductor of fig. 1;

fig. 9 is an expanded view of the inductor of fig. 1;

fig. 10 is a perspective view of a coil of the inductor of fig. 1 having support posts for forming an air gap;

FIG. 11 is a cross-sectional view taken along section line G-G of FIG. 10;

fig. 12 is a front-end fabrication flow of the air-bridge structure of the inductor of fig. 11;

fig. 13 is a mid-section fabrication flow of the air bridge structure of the inductor of fig. 11;

fig. 14 is a back end fabrication flow of the air bridge structure of the inductor of fig. 11;

fig. 15 is a perspective view of a comparative example one;

fig. 16 is a perspective view of a second comparative example;

FIG. 17 is a schematic diagram illustrating the correspondence between the inductance and the frequency of the first embodiment, the first comparative example, and the second comparative example;

FIG. 18 is a schematic diagram illustrating the correspondence between the Q value and the frequency of the first embodiment, the first comparative example, and the second comparative example;

fig. 19 is a schematic diagram of a second embodiment of an inductor of the present invention;

fig. 20 is a partial structural perspective view of a third embodiment of the inductor of the present invention;

fig. 21 is a perspective view of a third comparative example;

FIG. 22 is a schematic diagram illustrating the correspondence between the inductance value and the frequency of the second embodiment and the third embodiment;

FIG. 23 is a schematic diagram illustrating the correspondence between the Q value and the frequency of the second embodiment and the third embodiment;

fig. 24 is a partial structural perspective view of a fourth embodiment of the inductor of the present invention;

FIG. 25 is a cross-sectional view taken along section line H-H of FIG. 24; and

Fig. 26 is a partial structural perspective view of a fifth embodiment of the inductor of the present invention.

Detailed Description

First embodiment

Referring to fig. 1, an inductor 50 according to a first embodiment of the present invention includes a first layer metal 2 (bottom), a second layer metal 3 (top), and an interlayer connection. The interlayer connection connecting the first layer metal 2 and the second layer metal 3 includes a first interlayer connection 4a and a second interlayer connection 4b, and the second layer metal 3 is in contact with the first layer metal 2 at the interlayer connection. Fig. 2 is a schematic view in which the first layer metal 2 and the first interlayer connection portion 4a overlap with the second interlayer connection portion 4b, fig. 3 is a schematic view in which the second layer metal 3 and the first interlayer connection portion 4a overlap with the second interlayer connection portion 4b, and fig. 4 is a schematic view in which the first layer metal 2, the second layer metal 3, the first interlayer connection portion 4a, and the second interlayer connection portion 4b overlap. The first and second external connection parts 2b and 3b have an included angle θ1 which is a multiple of 90 degrees, and the first and second layer metals 2 and 3 are provided with cut-out cuts 2a and 3a, respectively, in the direction of the outer circumference. It should be noted that fig. 2 to 4 illustrate the variations (corresponding to the air-bridge-free fulcrum box) derived from the first embodiment, in addition to the inductor 50 (corresponding to the air-bridge-free fulcrum box) with the number of turns X of 1.5, 1.25 and 1.75 as disclosed in the first embodiment.

As shown in fig. 5 to 8, the first external connection portion 2b and the second external connection portion 3b form an angle θ1 with respect to the coil center O. In the first embodiment, θ1 is 270 degrees. Fig. 9 is an expanded view illustrating the connection relationship between the first metal layer 2 and the second metal layer 3 and the number of turns X. The number of turns X of the inductor 50 is determined by the magnitude of the angle θ1 between the first external connection portion 2b and the second external connection portion 3 b. That is, the number of turns X of the inductor 50 is shown in formula (1).

X＝x1+x2+x1＝2x1+x2 (1)

Here, x1 is the number of turns between the first external connection portion 2b and the second interlayer connection portion 4b, that is, only the first layer metal 2 alone. The number of turns between the second external connection 3b and the first interlayer connection 4a, i.e. solely only the second layer metal 3, is also x 1. x2 is the number of turns between the first interlayer connection 4a and the second interlayer connection 4b, that is, the parallel connection of the first layer metal 2 and the second layer metal 3. Also, in the first embodiment, θ1=270 degrees, and x≡1.75.

Assuming that the first interlayer connection part 4a is connected to the second external connection part 3b and the second interlayer connection part 4b is connected to the first external connection part 2b, x=x2, X will be almost equal to 1. On the other hand, when the first interlayer connection part 4a and the second interlayer connection part 4b overlap, x=2x1, X will be almost equal to 2. In other words

1<X<2 (2)

The material of the substrate 1 may be an insulator or a semiconductor. Preferably, a material having an impedance value of 1kΩ·cm or more is used as the substrate 1. The substrate 1 is for example but not limited to high-resistance silicon, gallium arsenide, sapphire, polycrystalline alumina, or glass. However, in the present invention, the material of the substrate 1 is not limited.

The first metal layer 2 is not directly formed on the substrate 1, and another material may be provided between the substrate 1 and the first metal layer 2. For example, when a material having a relatively high dielectric constant is used for the substrate 1, silicon dioxide may be provided as an insulating layer between the substrate 1 and the first metal layer 2. The material of the first layer metal 2 and the second layer metal 3 may be a metal or an alloy containing gold, copper or aluminum as a main component, or may be an alloy of other metals.

Fig. 10 to 11 show an example of an inductor 51 having a bridge structure for forming the air gap 5 between the first layer metal 2 and the second layer metal 3. In this example, the outer peripheral side of the second-layer metal 3 is provided with a plurality of support posts 3c so that the second-layer metal 3 can be supported by the substrate 1, and thus an air gap 5 can be formed between the first-layer metal 2 and the second-layer metal 3. The support column 3c is formed to extend radially outward from the outer peripheral side of the second-layer metal 3, and is fixed to the substrate 1 at its front end in the axial direction. The support columns 3c are arranged at intervals along the periphery of the second-layer metal 3, and no electricity can flow between the support columns 3c and the second-layer metal 3. Although the support column 3c may be provided on the inner peripheral side of the second-layer metal 3, if the support column 3c is provided on the outer peripheral side of the second-layer metal 3 as shown in fig. 11, the second-layer metal 3 may be stably supported. When a high-frequency current flows through the annular coil, the current at the inner periphery of the annular coil is larger than the current at the outer periphery. Therefore, the position for mechanically supporting the second-layer metal 3 is provided on the outer peripheral side of the second-layer metal 3, and the influence on the high-frequency current can be reduced as compared with the arrangement on the inner peripheral side, thereby obtaining a higher Q value. When a current flows through the inductor, a magnetic field is generated on the inner peripheral side of the coil, and once the support column 3c is provided on the inner peripheral side of the coil, the area on the inner peripheral side is reduced, and the inductance value is also reduced, so that the support column 3c is preferably provided on the outer peripheral side of the second metal layer 3. However, from the viewpoint of securing mechanical strength, a small number of support positions may be provided on the inner peripheral side.

The characteristics of the inductor with the empty bridge structure are researched by means of three-dimensional electromagnetic field simulation comparison. In the inductor 50 of the first embodiment, the thickness of the first layer metal 2 is 0.3 to 3.5 μm, the thickness of the second layer metal 3 is 3 to 12 μm, the thickness of the first layer metal 2 is smaller than the thickness of the second layer metal 3, the height Δh of the air gap 5 therebetween is 2 to 7.5 μm, the outer circumferential diameter of the circular ring is 400 μm, the metal width a is 70 μm, and the number of turns X is 1.75 turns, at which time the inductance value is 1.8nH, the maximum Q value is 70, the frequency at which the maximum Q value is obtained is 6.5GHz, the cut-off frequency is above 15GHz, the first layer metal 2 and the second layer metal 3 may be located at the same position in the vertical direction of the substrate 1, but may also be different, the radial deviation between the inner edge of the first layer metal 2 and the inner edge of the second layer metal 3 is 10 μm or less, and the width of the cuts 2a, 3a are 5 μm or more and 50 μm or less. The number of turns of the outer metal ring and the number of turns of the inner metal ring may be the same or different.

Fig. 12 to 14 show an example of a manufacturing flow of the hollow bridge structure. First, in order to form the first metal layer 2 and the support posts 3c, as shown in fig. 12 (a), a first seed layer 40 is formed on a substrate 1 made of an insulator or a semiconductor by electroless plating. Next, as shown in fig. 12 (b), a first barrier layer 41 is coated on the first seed layer 40.

Next, as shown in fig. 12 (c), exposure 42 is performed by a mask not shown, and as shown in fig. 12 (d), the exposed portions are etched away to form a barrier removed region 41a and a barrier removed region 41b. In the first barrier layer 41 and the corresponding etching process, a process and a material for removing the unexposed portion by etching may be selected. The removed area 41a of the barrier layer is created for forming the first layer of metal 2 to form an annular shape with the cut 2a in fig. 10. The barrier removed region 41b is created to form the lower portion 3c1 of the support column 3c to form an island region at the outer periphery of the barrier removed region 41 a.

As shown in fig. 12 (e), the first metal layer 2 is formed in the removed region 41a of the barrier layer and the lower portion 3c1 of the support column 3c is formed in the removed region 41b of the barrier layer by electrolytic plating. Next, as shown in fig. 12 (f), the remaining first barrier layer 41 is removed. Next, as shown in fig. 13 (a), the first seed layer 40 is removed by etching in the areas other than the areas under the first metal layer 2 and under the lower portions 3c1 of the support columns 3c.

As shown in fig. 13 (b), a second barrier layer 44 is formed as a sacrificial layer on the first metal layer 2 between the first metal layer 2 and the lower portion 3c1 of the support column. However, for the first interlayer connection portion 4a and the second interlayer connection portion 4b shown in fig. 10, the removed portion of the second barrier layer 44 is provided on the first metal layer 2. After the second barrier layer 44 is coated, as shown in fig. 13 (c), a second seed layer 45 is formed on the substrate 1 by electroless plating to cover the lower portions 3c1 of the support columns 3c and the second barrier layer 44.

Next, as shown in fig. 13 (d), a third barrier layer 46 is coated on the second seed layer 45. As shown in fig. 13 (e), exposure 47 is performed to the formation region of the second metal layer 3 and the formation region of the support post 3c through a mask not shown. Thereafter, the exposed portions are etched and developed, whereby a barrier layer removed region 46a of the third barrier layer 46 is formed as shown in fig. 13 (f). The process and materials used to etch the unexposed portions of the third barrier layer 46 and corresponding etching processes may also be selected.

Next, as shown in fig. 14 (a), a second layer metal 3 and upper portions 3c2 of the support columns 3c are formed in the barrier removal region 46a by electrolytic plating. The third barrier layer 46 is then removed as shown in fig. 14 (b). Thereafter, as shown in fig. 14 (c), the second seed layer 45 is removed by etching. In this way, the lower portion 3c1 and the upper portion 3c2 of the support column 3c are formed. Then, the second barrier layer 44 is etched to remove the first metal layer 2, the second metal layer 3, and the air gaps 5 between the support posts 3c. In other words, an empty bridge configuration with the air gap 5 between the first layer metal 2 and the second layer metal 3 is achieved.

The inductor 50 of the first embodiment has a structure in which the first layer metal 2 and the second layer metal 3 overlap each other when viewed from a direction perpendicular to the substrate 1, and the first layer metal 2 and the second layer metal 3 are connected in parallel between the first interlayer connection portion 4a and the second interlayer connection portion 4b. Thus reducing the loss caused by skin effect.

Further, the first layer metal 2 and the second layer metal 3 have overlapping positions spaced apart from each other as seen in a direction perpendicular to the substrate 1, and the inner peripheral side and the outer peripheral side of the coil have no divided spiral coil structure. Therefore, the proximity effect caused by the helical coil structure can be avoided. That is, the spiral inductor causes a phenomenon that eddy current is generated on the inner peripheral side due to a magnetic field generated by current passing through the coil on the outer peripheral side due to a proximity effect. Therefore, the loss increases due to the reduction of the sectional area of the inner peripheral side of the current path by the eddy current, and this loss increase lowers the Q value. However, in the coil structure of the present invention, since there is no helical coil structure, loss due to proximity effect can be avoided. Further, since the first layer metal 2 and the second layer metal 3 are connected in parallel in a specific region, the proximity effect is reduced and a higher Q value is obtained.

Further, when an inductor is provided in the IPD circuit pattern, the relationship between the first external connection portion 2b and the second external connection portion 3b is determined, and thus not only the degree of freedom of arrangement is restricted, but also the necessary extra wiring may deteriorate the circuit characteristics. However, in the present invention, the first layer metal 2 and the second layer metal 3 are connected in parallel at intervals in the direction perpendicular to the substrate 1, so that a higher Q value can be obtained.

To confirm that a high Q value can be obtained, an inductor 60 as in comparative example one in fig. 15 and an inductor 61 as in comparative example two in fig. 16 are provided. The first comparative example and the second comparative example both have a spiral coil structure. As shown in fig. 15 and 16, the first metal layer 10 has a first external connection portion 14, and the second metal layer 11 has a second external connection portion 19.

In a first comparative example shown in fig. 15, the coil on the outer peripheral side has an air bridge structure in which an air gap 12 is provided between the first layer metal 10 and the second layer metal 11. The coil on the inner periphery side has an air bridge structure in which an air gap 17 is provided between the first layer metal 15 and the second layer metal 16. By providing the cutouts 10a and 11a in the first layer metal 10 and the second layer metal 11 on the outer peripheral side, respectively, the number of turns can be made almost 1. The first metal layer 10 and the second metal layer 11 on the outer peripheral side are connected in parallel by interlayer connection portions 13a, 13b, 13c, and 13 d. The first layer metal 15 is connected in series with the first layer metal 10 and the second layer metal 16 is connected in series with the second layer metal 11. The first layer metal 15 and the second layer metal 16 on the inner peripheral side are connected in parallel to the interlayer connection portion 18b through the interlayer connection portion 18 a.

One end of the first metal layer 10 on the outer circumference side is provided with a first external connection portion 14, and one end of the second metal layer 16 on the inner circumference side is provided with a second external connection portion 19, which, like the first embodiment, has an included angle θ1 in the outer circumference direction, that is, a configuration of 270 degrees apart. Therefore, the number of turns of the first layer metal 15 and the second layer metal 16 on the inner peripheral side is almost 0.75. Therefore, the total number of turns of the first comparative example was almost 1.75 as in the first example.

In the second comparative example shown in fig. 16, compared with the first comparative example, the air gap 12 between the first metal layer 10 and the second metal layer 11 on the outer peripheral side is not provided, the first metal layer 10 and the second metal layer 11 are stacked on each other and electrically connected, and the air gap 17 between the first metal layer 15 and the second metal layer 16 on the inner peripheral side is not provided, and the first metal layer 15 and the second metal layer 16 are stacked on each other and electrically connected. Thus, the total number of turns of the second comparative example was almost 1.75 as in the first example.

The substrates used in the first, comparative examples one, and comparative example two were gallium arsenide (GaAs) and had a thickness of 20 μm. The coil materials of the first example, the first comparative example and the second comparative example are gold (Au), the thickness of the first metal layer is 3 μm, and the thickness of the second metal layer is 4 μm. The first and second comparative examples were both circular, and the outer circumference diameter was 400 μm as well, and had an inductance value of 1.8nH as the first example at a frequency of 5 GHz.

In order to make the inductance values of the first embodiment, the first comparative example, and the second comparative example identical, the widths a of the first and second layer metals 10 and 11 on the outer periphery side, the widths B of the first and second layer metals 15 and 16 on the inner periphery side, and the intervals S of the outer and inner periphery side layer metals are adjusted for the first and second layer metals 10 and 11 of the first and second comparative examples. Here, in order to reduce the loss due to the proximity effect in the process of adjusting the width a of the layer metal and the width B of the layer metal, the widths B of the layer metals 15, 16 on the inner circumference side are about half the widths a of the layer metals 10, 11 on the outer circumference side. Specifically, the width of the first layer metal 2 and the second layer metal 3 of the first embodiment in the radial direction thereof is 70 μm. In contrast, the width a of the first and second layer metals 10, 11 on the outer peripheral side of the comparative example was 40 μm, and the width a of the first and second layer metals 10, 11 on the outer peripheral side of the comparative example was 45 μm. The widths B of the first and second metal layers 15 and 16 on the inner peripheral sides of the first and second comparative examples are 20 μm. The interval S between the first layer metal and the second layer metal on the inner and outer peripheral sides of the first and second comparative examples was 20. Mu.m.

Fig. 17 depicts the correspondence between the inductance value and the frequency of the first embodiment (W1), the first comparative example (C1), and the second comparative example (C2), and it can be seen that the inductance values are almost the same.

Fig. 18 is a graph in which the correspondence between Q value and frequency in the above three cases is repeatedly written, that is, the comparison of the first embodiment (W1), the comparison of the first embodiment (C1), the comparison of the second embodiment (C2), the different loop widths (loop widths), the setting of the different turns, the formation of the same inductance value, and the generation of the different Q-frequency curve, 70 in the first embodiment (W1) of the present invention is realized as the maximum Q value, 64 in the comparison of the first embodiment (C1), and 59 in the comparison of the second embodiment (C2), is smaller than the first embodiment of the present invention, and therefore, it can be seen that the present invention is effective for increasing the Q value.

Second embodiment

Fig. 19 shows an inductor 40 according to a second embodiment of the present invention. An inductor structure with a larger inductance value is manufactured in a smaller area, and is composed of an outer metal ring and an inner metal ring, and the outer metal ring is identical to the first embodiment except that the cross of the drawer part is increased, referring to a schematic plan view structure.

The inner side is constructed of metal rings of which the first and second layers are separated by an air bridge in the vertical direction and connected in parallel, but since the outer connection portion protrudes to the outer circumference through a cutout of the outer metal ring, the number of turns is slightly more than one turn.

With this structure, the inductance value is about 1.8 times the inductance value of the inductor of the first embodiment compared with the inductor of the first embodiment of the same outer peripheral dimension, specifically, the inductance value of the inductor is about 3.8nH in the case of the outer peripheral diameter 400 μm of the inductor of the second embodiment.

Third embodiment

Fig. 20 shows an inductor 52 according to a third embodiment of the invention. The same partial composition as in fig. 1 is shown in fig. 20. The first external connection portion 2b and the second external connection portion 3b of the inductor 52 form an angle θ2 with respect to the coil center O. The angle θ2 of the third embodiment is about 90 degrees. The total number of turns of the inductor 52 is almost 1.25.

Fig. 21 shows an inductor 62 of a third comparative example. The inductor 62 has the same inner diameter, outer diameter, and thickness as the first layer metal 2 and the second layer metal 3 of the third embodiment. Further, the third comparative example is the same as the inductor 52 of the third embodiment: the first external connection portion 2b and the second external connection portion 3b form an angle θ2 (=90 degrees) with the coil center O as the center. In the third comparative example, an air gap 5 is formed between the first metal layer 2 and the second metal layer 3 in the region 20 between the first external connection portion 2b and the cutout 3a of the second metal layer 3. On the other hand, in the third comparative example, the region 21 other than the air gap 5 is formed in the region 20, and the first layer metal 2 is directly stacked on the second layer metal 3 to form an electrical connection. The total number of turns of the third comparative example was almost 1.25 as that of the third example.

Fig. 22 is a graph showing the comparison of the inductance value (L) versus the frequency (GHz) of the third embodiment (W3) and the third comparative example (C3). As shown in fig. 22, in the high frequency range of 0GHz to 15GHz, the inductance value (L) of the third example (W3) is almost the same as that of the third comparative example (C3), and the third example is shifted between the range of 0.9nH to 1.2 nH.

Fig. 23 is a graph of Q value versus frequency (GHz) for the third example (W3) and the third comparative example (C3). As shown in fig. 23, the Q value of the third example (W3) was higher than that of the comparative example 3 (C3) in the high frequency range of 1.3GHz to 15 GHz.

The reason why the Q value of the third example (W3) is higher than that of the comparative example 3 (C3) is as follows. In the third embodiment, the air gap 5 is formed between the first interlayer connection part 4a and the second interlayer connection part 4b, and the areas where the air gap 5 is formed are connected in parallel, so that the skin effect can be reduced. On the other hand, in the region 21 of the third comparative example, the first layer metal 2 and the second layer metal 3 are directly overlapped without the air gap 5, and thus the skin effect cannot be reduced. Thus, a difference in Q value between the third embodiment described in fig. 23 and the third comparative example was caused.

Fourth embodiment

Fig. 24 and 25 show an inductor 53 according to a fourth embodiment of the present invention. In the inductor 53 of the fourth embodiment, an insulating material 23 having a low dielectric constant is provided instead of the air gap 5 in the inductor 52 of the third embodiment shown in fig. 20. The insulating material 23 is, for example, polyimide resin having a low dielectric constant. Other materials having a low dielectric constant may be used for the insulating material 23. The insulating material 23 need not be provided over the entire circumference of the coil, and may be provided so as to be dispersed in the circumferential direction.

In the inductor 53 of the fourth embodiment, although the cut-off frequency decreases because of an increase in parasitic capacitance between the first layer metal 2 and the second layer metal 3, a decrease in cut-off frequency is acceptable in some cases. In the fourth embodiment, since the insulating material 23 is provided between the first layer metal 2 and the second layer metal 3, the mechanical strength of the first layer metal 2 and the second layer metal 3 is maintained. Therefore, according to the fourth embodiment, the support column 3c shown in fig. 10 is not required.

Fifth embodiment

Fig. 26 shows an inductor 54 of a fifth embodiment of the present invention in which quadrangles are formed spirally. The inductor 54 of the fifth embodiment is provided with the first layer metal 24 provided with the notch 24a on a substrate not shown in the figure. The second layer metal 25 is arranged with an air gap 26 from said first layer metal 24 in a direction perpendicular to the substrate. The first layer metal 24 and the second layer metal 25 have a quadrangle with the same size, and the second layer metal 25 is formed with a slit 25a that cuts off the coil in the outer circumferential direction. That is, the number of turns of each of the first layer metal 24 and the second layer metal 25 is less than 1.

At one end of the first metal layer 24, a first external connection portion 24b for connecting wires or components other than the inductor 54 is provided. The other end of the first metal layer 24 is electrically connected to the second metal layer 25 through a first interlayer connection portion 27 a. One end of the second metal layer 25 is offset from the first external connection portion 24b of the first metal layer 24. One end of the second metal layer 25 is provided with a second external connection portion 25b for connecting wires or components other than the inductor 54. The other end of the second metal layer 25 is electrically connected to the first metal layer 24 through the second interlayer connection portion 27 b.

As in the fifth embodiment, even if the shape of the coil is designed in a quadrangle, a higher Q value can be obtained as compared with a quadrangle spiral coil inductor. In the case of the fifth embodiment, the number of turns can be arbitrarily changed between 1 and 2 by changing the interval in the outer circumferential direction between the first external connection portion 24b and the second external connection portion 25b. In the case where the coil shape is polygonal, the coil shape is not limited to square, but may be polygonal having a pentagon or more, preferably, for example, octagonal or more, and a characteristic similar to a circle can be obtained.

In summary, even if the first layer metal 2 and the second layer metal 3 are replaced, the essence of the invention is not changed; in addition, instead of using a gas bridge, an insulating material 23 having a smaller dielectric constant and a larger thickness may be used between the first layer metal 2 and the second layer metal 3, and this material may be polyimide resin, for example, and the parasitic capacitance between the first layer metal 2 and the second layer metal 3 may be increased and the cut-off frequency may be decreased as compared with the gas bridge.

The inductor of the present invention may be an inductor formed of upper and lower metal layers as in the first embodiment, or may be an inductor formed of an outer metal ring and an inner metal ring in the second embodiment, wherein the inner metal ring may be formed of upper and lower metal layers, or may be a single metal layer.

The foregoing is merely illustrative of the preferred embodiments of the present invention and is not intended to limit the scope of the invention, which is defined by the appended claims and their equivalents.

Claims (11)

1. An inductor characterized by having a two-layer structure formed on a semiconductor or insulator substrate, the first and second layers each having less than one turn and having overlapping portions in plan view, the total number of turns exceeding one turn and less than two turns, the inductor having two external connection portions as first and second external connection portions, respectively, the first and second layers being connected by at least a first interlayer connection portion near the first external connection portion and a second interlayer connection portion near the second external connection portion, the first layer being connected in series from the first external connection portion to the first layer of the second interlayer connection portion, and the second layer being connected in series from the second interlayer connection portion to the second external connection portion, the first layer and the second layer being connected in parallel from the first interlayer connection portion to the second interlayer connection portion, being spaced apart in a vertical direction.

2. The inductor of claim 1 wherein the first layer and the second layer are metal rings, the outer perimeter of the first layer having a portion of the inductor and the outer perimeter of the first layer and the inner Zhou Chuanlian of the first layer, the outer perimeter of the second layer having a portion of the inductor and the outer perimeter of the second layer and the inner Zhou Chuanlian of the second layer.

3. The inductor according to claim 1 or 2, characterized in that the first layer and the second layer have a ring shape with a cutout, the ring shape being a circular ring shape or a polygon of four or more sides with no metal in a center portion.

4. An inductor according to claim 1 or 2, characterized in that the radial deviation between the inner edge of the first layer and the inner edge of the second layer is 10 μm or less.

5. An inductor according to claim 1 or 2, wherein the second layer is a gas bridge structure, serving to support the gas bridge structure comprising a first interlayer connection and a second interlayer connection and/or a plurality of support posts located at the periphery of the second layer.

6. The inductor of claim 5, wherein the support post extends radially outward from the second layer outer peripheral side and is located outside the inductor in a torus shape or a polygonal shape.

7. The inductor according to claim 1 or 2, wherein the first layer is metal and has a thickness of 0.3-3.5 μm; the second layer is made of metal, the thickness of the second layer is 3-12 mu m, and the height of an air gap between the first layer and the second layer is 2-7.5 mu m.

8. The inductor of claim 7, wherein a thickness of the first layer is less than a thickness of the second layer.

9. The inductor of claim 2, wherein the outer metal ring and the inner metal ring of the inductor are each of a two-layer structure, and the number of turns of the outer metal ring and the number of turns of the inner metal ring of the inductor are the same or different.

10. An inductor according to claim 1 or 2, characterized in that an insulating material is used between the first and second layers, said insulating material being arranged directly between the whole first and second layers or the insulating material being arranged between the first and second layers at intervals.

11. A method of manufacturing an inductor according to any one of claims 1-10, characterized by the steps of:

a. defining a first region and a second region which are spaced from each other on a substrate, and forming a first metal layer on the first region and the second region to form a first layer positioned in the first region and a lower part of a support column positioned in the second region;

b. forming a sacrificial layer between the first layer and the lower parts of the first layer and the support columns, wherein the sacrificial layer is formed to expose the first layer from two third areas;

c. forming a second metal layer on the lower parts of the sacrificial layer and the support part to form an upper part covering the lower part of the support column, a second layer covering the sacrificial layer, two interlayer connection parts which are positioned in a third area and connect the first layer and the second layer, wherein the first layer and the second layer between the first interlayer connection part and the second interlayer connection part are connected in parallel and are spaced in the vertical direction; and

d. the sacrificial layer is removed.