JPH02232962A - Integrated circuit - Google Patents

Abstract

PURPOSE:To make an integrated circuit of this design large in inductance per unit area by a method wherein the direction of magnetic flux is made parallel with a semiconductor board by the three-dimensional arrangement of a coil. CONSTITUTION:An integrated inductor is constituted so as to make the direction of magnetic flux parallel with the faces of active layers 1a and 1b using planes 3a and 3b and an interlaminar wiring 4 formed inside the active layers 1a and 1b which are provided through the intermediary of an interlaminar insulating film 2. When a winding is increased in number of turns, the length of the inductor in a lengthwise direction becomes larger than that in a crosssectional direction and the magnetic flux grows small in leakage, and the inductor is restrained from decreasing in effective inductance. When area required for the winding is taken into consideration, only a single wiring can do with a turn of the winding from the viewpoint vertical to the face of the active layer, so that the inductor of this design is remarkably increased in inductance per unit parallel to the active layer.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an integrated circuit, and more particularly to a semiconductor integrated circuit in which an inductor and a transformer are integrated, and these are simultaneously integrated and used as circuit elements.

[Conventional technology]

Inductors are used in electronic circuits as essential elements for LC resonant circuits and LC filters, or for applications that utilize high impedance at high frequencies, while transformers are widely used for transmitting small signals or power. Both are common elements, but they are not as integrated as transistors.

FIG. 5 is a diagram showing an example of an inductor used in a conventional integrated circuit, in which figure a) is a sketch and figure b) is a circuit diagram.

In an inductor that achieves a required inductance using a winding 8 spirally formed on a semiconductor substrate 7, the inductance value is generally determined by the area through which the magnetic flux passes and the magnetic permeability of the portion through which the magnetic flux passes. Ru. Therefore, in the integrated inductor shown in FIG. 5, once the material of the semiconductor substrate is determined, since the direction of the magnetic flux is perpendicular to the semiconductor substrate, the area used for wiring is equal to the area through which the magnetic flux passes. Inductance depends on the number of turns of the winding and the wiring area.

[Problem to be solved by the invention]

In the conventional inductor as described above, the direction of the magnetic flux is the normal direction of the semiconductor substrate, so there is a problem that the inductance per unit area cannot be increased. The reason is 2
One is that if the windings are arranged under certain design rules, the wiring area will increase as the number of turns increases, and the other is that the windings are formed on a single plane. This is a decrease in effective inductance due to magnetic flux leakage caused by Further, due to the latter reason, there was a problem that a transformer could not be constructed because the degree of coupling could not be maintained.

The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide an integrated circuit that can form an inductor with a large inductance per unit area or a transformer with a sufficiently large degree of coupling.

[Means to solve the problem]

The integrated circuit according to the present invention has three-dimensional winding using two-layer planar wiring and interlayer wiring perpendicular to it, so that the direction of magnetic flux is parallel to the semiconductor substrate. An integrated inductor with a large inductance and a small leakage of magnetic flux, or an integrated transformer with a large degree of coupling.

[Effect]

In the integrated inductor of the present invention, since the direction of magnetic flux is parallel to the semiconductor substrate, the inductance per unit area can be increased. Further, leakage of magnetic flux can be reduced by making the length of the inductor in the longitudinal direction larger than the cross section through which the magnetic flux passes.

Furthermore, in addition to the above-mentioned shape, an integrated transformer having a large degree of coupling can be constructed by arranging two wires very close to each other to construct a winding shape with little magnetic flux leakage.

〔Example〕

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

Fig. 1 a) is a sketch showing the structure of an integrated inductor according to an embodiment of the present invention, Fig. 1 b) is a view seen from the direction parallel to the semiconductor substrate in Fig. 1 (S direction), and Fig. 1 C) is a diagram showing the structure of an integrated inductor according to an embodiment of the present invention. FIG. 2 is a circuit diagram of an integrated inductor. In Figure 1 a), la*1
b is an active layer, 2 is an interlayer insulating film, 38t a b is a planar wiring, and 4 is an interlayer wiring.

The integrated inductor of the present invention has two active layers 1a. ll) Planar wiring aa*s formed in
b and interlayer wiring 4 so that the direction of magnetic flux is parallel to the surface of the active layer. When the number of turns of the winding is increased, the length of the inductor in the longitudinal direction becomes longer than the cross-sectional direction, which reduces leakage of magnetic flux and suppresses a decrease in effective inductance. In addition, when considering the area required for the winding, since only one wire is required per turn of the winding from the direction perpendicular to the surface of the active layer, the inductance per unit area seen from above is greatly increased. do.

Figure 2 shows the planar wiring 3a*3 of the integrated inductor in Figure 1.
FIG. 7 is a sketch showing another embodiment of the present invention in which the wiring shape of FIG. By making the planar wirings 3a and 3b into this shape, the magnetic path is closed, so that leakage magnetic flux can be extremely reduced.

FIG. 3 is a diagram showing an integrated transformer according to another embodiment of the present invention. Similar to FIG. 1, Figure a) is a sketch, and Figure b) is a circuit diagram. In figure a), θas9b is the first,
This is the second wiring, and similarly to the integrated inductance shown in FIG. 1, the active layer 1a.
It is composed of a planar wiring 3 al 3 b formed in ib and an interlayer wiring 4, which are arranged adjacent to each other so as to have a sufficient degree of coupling. Naturally, in constructing this integrated transformer, the toroidal type shown in FIG. 2 can be used.

FIG. 4 shows another embodiment of the present invention in which the integrated transformer shown in FIG. 3 is integrated at the same time as an active element, and the first circuit block 5a and the second circuit block 5a integrated on the semiconductor substrate are used. The output signal of the first circuit block 5a is transmitted to the second circuit block 5b, which is insulated from the first circuit block 5a, by the integrated transformer 8 located between the first circuit block 5a and the first circuit block 5b. With this configuration, the fourth
Each of the circuit parts shown in the figure can be made smaller and lighter.

〔Effect of the invention〕

As described above, according to the present invention, an inductor with large inductance per unit area can be constructed by making the direction of magnetic flux parallel to the semiconductor substrate by arranging the windings three-dimensionally. Furthermore, by arranging the inductors adjacent to each other, a transformer can be formed, and by integrating other circuit elements at the same time, it is possible to reduce the size and weight of circuit systems that require inductors and transformers. There is.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the configuration of an integrated inductor according to an embodiment of the present invention, in which Figure a) is a sketch, Figure b) is a sectional view, and Figure C
) is a circuit diagram, FIG. 2 is a diagram showing the configuration of an integrated inductor according to a second embodiment of the present invention, and FIG. 3 is a diagram showing the configuration of an integrated transformer according to another embodiment of the present invention. Figure a) is a sketch, Figure b) is a sectional view, Figure C) is a circuit diagram, and Figure 4 is another embodiment of the present invention in which electronic circuits are integrated using the integrated transformer of the present invention shown in Figure 3. FIG. 5 is a diagram showing an inductor used in a conventional integrated circuit, in which figure a) is a sketch and figure b) is a circuit diagram. In the figure, la+1b are the first and second active layers, 2 is an interlayer insulating film, 3as3b is the first and second plane wiring, 4 is the interlayer wiring, 5a# 5b is the first and second circuit block , 6 is an integrated transformer, 7 is a semiconductor substrate, 8 is a winding wire,
9 al 9 b are first and second wirings. Note that the same reference numerals in the figures indicate the same or equivalent parts. Patent applicant: Director of the Agency of Industrial Science and Technology Yuki Iizuka 31 Figure 2 Figure 2

Claims (1)

[Claims] 1) In an integrated circuit having two or more active layers with an interlayer insulating film interposed therebetween, the direction of magnetic flux is parallel to the active layer using two layers of planar wiring and interlayer wiring. What is claimed is: 1. An integrated circuit comprising an integrated inductor or an integrated transformer configured three-dimensionally.