JPH04274304A - Inductor for integrated circuit - Google Patents

Abstract

PURPOSE:To provide a product, which has an occupied area smaller in relation to the magnitude of its inductance and which causes less noise emissions, by providing ferromagnetic layers on both sides of a conductor path, which is laid over a substrate, without a substantial contact therebetween. CONSTITUTION:Firstly, two layers are formed over a substrate 2 in the order of a ferromagnetic layer 4b and an insulating layer 5b. Then, a conductor path 3 is vapor-deposited over these layers. And thirdly, an insulating layer 5a and then a ferromagnetic layer 4a are further superimposed over the conductor path 3. The conductor path 3 is not limited to a coiled pattern, but may be replaced with a linear pattern. The ferromagnetic layers 4a and 4b are made up of ferrite. In an integrated circuit 1 with the aforementioned structure, a magnetic field emerging around the conductor path 3 is confined between the ferromagnetic layers 4a and 4b, thereby augmenting the inductance of the IC. Thus, it becomes possible to provide a product which occupies less area and emits less noise.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to inductors for integrated circuits. More particularly, the present invention relates to a novel configuration of an inductor that can be built on a substrate as an integrated circuit element along with semiconductor elements and the like.

0002

2. Description of the Related Art Recent advances in integrated circuit manufacturing technology have been remarkable, and it has become possible to integrate circuits containing almost all types of elements.

FIG. 2 is a diagram illustrating a typical configuration of an inductor that can be built onto a substrate for an integrated circuit.

As shown in the figure, this inductor 1 is
It consists of a coiled conductor line 3a formed on the substrate 2, and a straight conductor line 3b for connecting the central end of the coiled conductor line 3a to the outside. Note that an insulating layer is provided between the coiled conductor line 3a and the straight conductor line 3b to prevent a short circuit between the intermediate portion of the coiled conductor line 3a and the straight conductor line 3b.

[0005]

The conventional inductor for integrated circuits constructed as described above has the following problems.

That is, since the inductance of this inductor depends exclusively on the number of turns of the coiled conductor line 3a, if an inductor with a large inductance is to be manufactured, its occupied area will inevitably increase. In other words, there is a limit to the inductance of an inductor that can actually be fabricated in an integrated circuit.

Furthermore, since inductors built into integrated circuits generally emit a large amount of noise, it is very difficult to handle them in integrated circuits with high integration density.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the above-mentioned problems of the prior art, and to provide a new inductor for integrated circuits that occupies a small area compared to the size of its inductance and emits less noise. is its purpose.

[0009]

[Means for Solving the Problems] That is, according to the present invention,
An inductor for use in an integrated circuit including a conductor line formed on a substrate, comprising a ferromagnetic layer formed substantially adjacent to the conductor line in a predetermined section of the conductor line. An inductor for integrated circuits is provided.

0010

The main feature of the inductor for an integrated circuit according to the present invention is that it includes a conductor line and a ferromagnetic layer formed substantially adjacent to the conductor line.

[0011] Conventional inductors for integrated circuits have been constructed of coiled conductor lines formed on a substrate, so while the area occupied on the substrate is large, the obtained inductance is small, and the noise emitted is small. It was also big.

In contrast, in the inductor for integrated circuits according to the present invention, by providing a ferromagnetic layer adjacent to the conductor line on the substrate, the magnetic field formed around the conductor line is reduced by the ferromagnetic layer. In addition to increasing its inductance, it also suppresses noise radiation to the outside. Further, since the conductor line itself does not need to be formed into a coil-like pattern, the area occupied on the substrate is significantly reduced compared to a conventional inductor.

The ferromagnetic layer in the inductor for integrated circuits according to the present invention can be formed of, for example, ferrite.

Furthermore, since ferrite and other ferromagnetic materials are generally not perfect insulators, if a ferromagnetic layer is formed directly above or below a conductor line, there is a risk that the ferromagnetic layer will short-circuit the conductor line. be. Therefore, it is preferable to form an insulating layer between each conductor line and the ferromagnetic layer.

[0015] Hereinafter, the present invention will be explained in more detail with reference to Examples. However, the following disclosure is merely an example of the present invention, and is not intended to limit the technical scope of the present invention in any way.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a side view showing a specific example of the structure of an inductor for integrated circuits according to the present invention.

As shown in the figure, this inductor for an integrated circuit includes a conductor line 3 formed on a substrate 2, and a pair of ferromagnetic layers 4a and 4b formed to sandwich the conductor line 3.
It is mainly composed of. Further, between the conductor line 3 and the ferromagnetic layers 4a and 4b, there are insulator layers 5a and 5, respectively.
b is formed.

In the integrated circuit inductor 1 constructed as described above, the magnetic field generated around the conductor line 3 is confined within the ferromagnetic layers 4a, 4b. The inductance of the conductor line 3 in the sandwiched section increases.

[Manufacturing Example] An inductor having the structure shown in FIG. 1 was actually manufactured.

First, a 15 μm thick ferromagnetic layer 4b was formed on the substrate 2 by depositing glass containing CrO2. Subsequently, by depositing glass on the ferromagnetic layer 4b using a thick film printing method, a thickness of 20
An insulator layer 5b having a thickness of μm was formed. Next, by vapor deposition method,
A conductor line 3 was formed. Note that the conductor line 3 has a line width of 50 μm.
The pattern was a linear pattern with a thickness of 2 μm and a thickness of 2 μm. Thereafter, an insulating layer 5a and a ferromagnetic layer 4a were sequentially formed in a similar manner to obtain an inductor having the structure shown in FIG. 1.

[0021]

As explained above, the inductor for integrated circuits according to the present invention has a large inductance in a small occupied area due to its unique structure, and is particularly preferable as an integrated circuit element. Furthermore, it emits less noise, which makes it preferable as an integrated circuit element.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a specific configuration example of an inductor for an integrated circuit according to the present invention.

FIG. 2 is a diagram showing a conductor line pattern in a conventional inductor for integrated circuits.

[Explanation of symbols]

1 Inductor, 2　　　　　Substrate, 3 Conductor line, 3a Coiled conductor line, 3b Straight conductor line, 4a, 4b ferromagnetic layer, 5a, 5b Insulator layer

Claims (2)

[Claims] 1. An inductor for use in an integrated circuit including a conductor line formed on a substrate, the ferromagnetic material being formed substantially adjacent to the conductor line in a predetermined section of the conductor line. An inductor for an integrated circuit, comprising a layer. 2. The inductor for an integrated circuit according to claim 1, wherein the ferromagnetic layer is a ferrite layer formed above and/or below the conductor line via an insulating layer. Features of inductors for integrated circuits.