JP2002050740A - Spiral inductor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a spiral inductor, having a small area which has the same high Q-value, as viewed from both ends of the inductor. SOLUTION: First and second spirals are formed spirally inwards from a first and a second connection end 10, 11 which are disposed symmetrically about a center line 14 passing the center of the spiral. Within the same turn, the spirals on the same side with the connection ends are formed using the one and the same conductive interconnection layer, while the spirals on the opposite side from the connection end side are formed using other conductive interconnection layer, which is electrically separated by an insulating layer from the conductive interconnection layer. The different conductive interconnection layers are cross-connected through via holes 15 on the center line, with the first and second spirals being formed symmetrically with respect to the center line.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low-area spiral inductor having the same and high characteristics as viewed from both ends of an inductor, which is one of passive components used in a device handling high frequency.

[0002]

2. Description of the Related Art FIG. 2 shows the structure of a conventional spiral inductor. FIG. 2 (a) is a perspective view of the conventional spiral inductor, FIG. 2 (b) is a plan view, and FIG.
It is sectional drawing in the A 'line.

As shown in FIG. 2, a conventional spiral inductor includes a first conductor wiring layer 2 formed on a substrate 21.
2 and has a structure that spirally enters from the first connection end 23 toward the center and enters through a via hole 24 formed in the center of the inductor. It is configured to be guided to a second connection end 28 outside the inductor by using the lower second conductor wiring layer 27.

[0004]

However, in such a conventional structure, a difference in capacitance between the substrates occurs due to the difference in the conductor wiring layers used for the first and second connection ends. Furthermore, due to the capacitive coupling between the lead wiring and the inductor wiring, the Q value, which is an important characteristic of the inductor, differs between when viewed from the first connection end 23 and when viewed from the second connection end 28.

Therefore, when a conventional inductor is used as an inductor of a differential oscillator as shown in FIG. 3, two spiral inductors as shown in FIG. 4 are symmetrically arranged to maintain the symmetry of the inductor. It was necessary to make the characteristics seen from both connection ends of the inductor the same.

However, in the configuration shown in FIG. 4, two apparently required spiral inductors are required, and the manufacturing cost is increased due to the increase in the inductor area, and the capacitance between the conductive wiring layer forming the spiral and the substrate is increased. This results in deterioration of the Q value.

SUMMARY OF THE INVENTION In view of the foregoing, an object of the present invention is to provide a low-area spiral inductor having the same and high Q value as viewed from both ends of the inductor.

[0008]

In a spiral inductor according to the present invention, the positions of first and second connection ends for external connection are arranged symmetrically with respect to a center line passing through the center of the spiral. The first and second spirals are formed spirally inward from the first and second connection ends, and the first and second spirals are each disposed within the same turn with respect to the center line. The spiral on the same side as the connection end is formed using the same conductive wiring layer, and the spiral on the opposite side to each connection end is formed of another conductive material electrically separated from the conductive wiring layer by an insulating layer. It is formed using a wiring layer, and different conductive wiring layers are connected by a via hole on the center line.

[0009] This makes it possible to make the capacitance between the substrates and the capacitance between the spiral wires as viewed from both connection ends the same with a single spiral inductor, and to make the characteristics as viewed from both ends the same. , The Q value viewed from both connection ends can be the same.

Further, in the same turn, the first and second spirals formed of different conductive wiring layers are formed symmetrically with respect to the center line so that different conductive wiring layers are formed. It can be formed perpendicular to the substrate, the capacitance between the spiral wiring and the substrate can be reduced, and a high Q value can be realized.

As described above, a spiral inductor having the same high Q value as viewed from both ends can be realized with a small area.

[0012]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1A is a perspective view of a spiral inductor according to an embodiment of the present invention, and FIG.
FIG. 1C is a cross-sectional view taken along line AA ′, and FIG.
A cross-sectional view taken along the line is shown in FIG.

In the figure, 10 is a first connection end, 11 is a second connection end, 12 is a first conductive wiring layer, 13 is a second conductive wiring layer, 14 is a center line of an inductor, and 15 is a center line of an inductor. A via hole, 16 is a semiconductor substrate, 17 is a first insulating layer, and 18 is a second insulating layer.

As shown in FIG. 1, a spiral inductor according to the present embodiment includes a first insulating layer 17 formed on a semiconductor substrate 16 and a second conductive wiring formed on the first insulating layer 17. A layer 13, a second insulating layer 18 formed on the second conductive wiring layer 13, a first conductor wiring layer 12 formed on the second insulating layer 18, Wiring layer 1
2 has a via hole 15 for electrically connecting the second conductive wiring layer 13 to the second conductive wiring layer 13.

Here, the two connection ends 10 and 11 for connecting the spiral inductor to the outside are arranged symmetrically with respect to a center line 14 passing through the center of the spiral.

Of the spirals spiraling around the center of the spiral from the two connection ends, a spiral on the same side as each connection end from the center line is formed in the first conductive wiring layer 12, and the center line is formed. The spiral on the side different from each connection end is formed by the second conductive wiring layer 13, and the first conductive wiring layer 12 and the second conductive wiring layer 13
4 are cross-connected by via holes 15. That is, every time the spiral crosses the center line 14, the conductive wiring layer forming the spiral is changed, and each conductive wiring is connected by the via hole 15.

Further, in the spiral using the same conductive wiring layer forming the same number of turns starting from each connection end, the left and right shapes are formed geometrically symmetric with respect to the center line 14 as an axis.

Finally, the spirals starting from each connection end are connected on the center line 14 with the same wiring length and the same number of turns from each connection end.

Therefore, according to the present embodiment, in an apparently one inductor area, the wiring between the conductive wiring layer forming the spiral as viewed from the two connection ends and the capacitance between the substrate as viewed from the two connection ends. The capacity between them will be the same,
The Q value seen from the two connection ends can realize the same inductor, and furthermore, since the different conductive wiring layers are vertically overlapped with the substrate, the conductive wiring forming the spiral and the capacitance between the substrates can be reduced. it can.

Although the present embodiment has been described with reference to a square spiral shape drawing, other polygonal and circular spirals may be arranged with respect to the center line of the spiral.
It goes without saying that a spiral can be formed symmetrically.

In this embodiment, the example in which the spiral is formed using two conductive wiring layers has been described. However, as long as the left and right sides of the spiral are different wiring layers with respect to the center line,
It may be formed of three or more conductive wiring layers.

[0023]

As described above, according to the present invention, by forming and connecting two symmetrical inductors using a plurality of wiring layers, an inductor having the same Q value as viewed from each connection end can be reduced in area. And a reduction in the capacitance between the conductive wiring layer forming the spiral and the inter-substrate can realize a spiral inductor having a high Q value.

This leads to cost reduction and higher performance in realizing a semiconductor device, and the effect is extremely large.

[Brief description of the drawings]

1A is a perspective view of a spiral inductor according to an embodiment of the present invention, FIG. 1B is a plan view thereof, FIG. 1C is a cross-sectional view taken along line AA ′ of FIG. Line cross section

2A is a perspective view of a conventional spiral inductor, FIG. 2B is a plan view thereof, and FIG.

FIG. 3 is a circuit diagram of a conventional differential oscillator using one inductor.

FIG. 4 is a plan view of a symmetrical inductor formed using a conventional spiral inductor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 First connection end 11 Second connection end 12 First conductive wiring layer 13 Second conductive wiring layer 14 Center line of inductor 15 Via hole 16 Semiconductor substrate 17 First insulating layer 18 Second insulating layer

Claims (2)

[Claims] 1. A spiral inductor formed by spirally forming a conductor wiring on a substrate, wherein a center line passing through the center of the spiral is provided at first and second connection ends for connection to the outside. The first and second spirals are symmetrically disposed with respect to each other, and have first and second spirals formed spirally inward from the first and second connection ends, wherein the first and second spirals are in the same turn. Then
The spiral on the same side as each connection end with respect to the center line is formed by using the same conductive wiring layer, and the spiral on the opposite side to each connection end is an insulating layer with the conductive wiring layer and electrically. A spiral inductor formed by using another conductive wiring layer separated into a plurality of conductive wiring layers, wherein the different conductive wiring layers are connected by a via hole on the center line. 2. The device according to claim 1, wherein the first and second spirals formed of different conductive wiring layers in the same turn are each formed symmetrically with respect to the center line. Spiral inductor.