JPH05190333A - Multilayered type spiral inductor - Google Patents

Abstract

PURPOSE:To obtain a spiral inductor of high inductance value improved in characteristics of a high frequency circuit by suppressing a parasitic capacitance susceptible to influence the high frequency circuit. CONSTITUTION:A semiconductor or insulator substrate 1 is surfaced with upper and lower spiral inductors 2, 4 via insulator legs 6, whereby the spiral inductors are formed multilayeredly with an air layer of small dielectric constant interposed between both inductors.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of an inductor used in a semiconductor circuit.

[0002]

2. Description of the Related Art Digital mobile phones and other mobile communications are carried out by radio frequency radio equipment, and the inductor shown in FIG. 5 for a semiconductor circuit of the radio equipment is a semiconductor substrate or an interlayer insulating film, that is, an insulating film. FIG. 7 is a plan view showing an example of a conventional inductor in which a two-layer spiral inductor is formed on a body substrate, FIG. 6 shows a VI-VI cross section of FIG. 5, and the two-layer spiral inductor is a substrate 1; The spiral inductor 2 of the first layer is formed on the spiral inductor 4, and the spiral inductor 4 of the second layer is formed on the spiral inductor 2 with the insulating film 3 interposed therebetween.
By electrically connecting 4 with the conductor 8 through the contact hole 5 in the central portion, a spiral inductor having a small area and a large conductance value is formed.

[0003]

However, in the multi-layer type spiral inductor having the above-mentioned insulating film, since the spiral inductor is multi-layered, it is possible to obtain a large inductance value with a small occupied area (outer dimension). However, since an insulating film with a high relative permittivity is interposed between the upper and lower spiral inductors, the parasitic capacitance due to electrostatic coupling becomes large, and digital mobile phones use microwaves, which causes static electricity. There is a drawback that the capacitance greatly affects the operating characteristics in the high frequency band.

[0004]

According to the present invention, a multi-layered spiral inductor is formed on a semiconductor substrate or an insulating substrate through an air layer between at least a first layer spiral inductor and a second layer spiral inductor. In order to improve the operation in the high frequency band by reducing the parasitic capacitance between the upper and lower inductors in the multilayer spiral inductor, the application of the air bridge technology with the air layer is applied. Has been achieved.

[0005]

There is no insulating film between the spiral inductor of the first layer and the spiral inductor of the second layer, and an air layer is present, and the relative permittivity (εs = 1) of this air causes the insulating film (SiO ₂ , SiN, etc.) to oxidize. Since it is smaller than the relative dielectric constant of the material insulating film), the parasitic capacitance generated between the upper and lower spiral inductors is reduced.

[0006]

1 is a plan view of the first embodiment, and FIG. 2 is a sectional view taken along the line II--II of FIG. 1, showing a semiconductor substrate. Alternatively, the spiral inductor 2 of the first layer is formed on the insulating substrate 1, and the spiral inductor 4 of the second layer is supported thereon by a plurality of legs 6 provided at predetermined positions on the upper surface of the substrate 1. And is electrically connected to the central portion of the lower spiral inductor 2 via the connecting conductor 8 in the central portion. The spiral inductors 2 and 4 of the first and second layers have the same winding direction and do not impair the value of the inductance generated therebetween, and an air layer having a small relative permittivity is interposed to reduce the parasitic capacitance. There is.

FIG. 3 is a plan view showing another embodiment of the present invention, and FIG. 4 is a sectional view taken along the line IV--IV of FIG.
The difference from the spiral inductor of the embodiment is the substrate 1
The spiral inductor 2 of the first layer formed on the surface of is also formed via the leg 6, and therefore the spiral inductor 4 of the second layer has a leg 7 higher than the leg 6 of the first layer. And the air layers are provided between the substrate 1 and the first layer and between the first layer and the second layer, respectively, and the upper and lower spiral inductors 2 and 4 are provided via the connecting conductor 8 in the central portion. They are electrically connected to form a multilayer spiral inductor, and the function thereof is not different from that of the embodiment shown in FIGS. Further, it is also possible to form a multilayer as described above.

[0008]

As is apparent from the above description, in the multi-layer spiral inductor of the present invention, the spiral inductor has a multi-layer structure with the air layer interposed, so that the air having a small relative permittivity is provided between the upper and lower spiral inductors. Since it exists only, the parasitic capacitance generated between the upper and lower spiral inductors can be reduced. Therefore, it was possible to improve the operation especially in the high frequency band.

[Brief description of drawings]

FIG. 1 is an enlarged plan view showing an example of a multilayer spiral inductor of the present invention.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is an enlarged plan view of another embodiment.

FIG. 4 is a sectional view taken along line IV-IV in FIG.

FIG. 5 is an enlarged plan view of a conventional spiral inductor.

6 is a sectional view taken along line VI-VI in FIG.

[Explanation of symbols]

 1 Substrate 2 1st Layer Spiral Inductor 4 2nd Layer Spiral Inductor 5 Contact Holes 6, 7 Legs 8 Conductor

Claims (2)

[Claims] 1. On a semiconductor substrate or an insulating substrate, 1
A multi-layer spiral inductor comprising a spiral inductor of the first layer provided in contact with the spiral inductor and an air layer formed between the spiral inductor of the first layer and the spiral inductor of the second layer. 2. A multi-layer spiral inductor comprising a first-layer spiral inductor and a second-layer spiral inductor formed on a semiconductor substrate or an insulating substrate with an air layer interposed therebetween.