JPH0637255A - Structure of lc circuit - Google Patents

Abstract

PURPOSE:To provide an LC circuit structure which can be lessened in chip area and length of connecting wiring so as to be minimized in influence to microwave characteristics. CONSTITUTION:A capacitor C and an inductor L are vertically provided onto a substrate 1 through the intermediary of an insulating film 5, and the capacitor C and the inductor L are electrically connected together with a connecting wiring 6 formed penetrating the insulating film 5.

Description

Detailed Description of the Invention

[0001]

The present invention relates to the structure of LC circuits. More specifically, the present invention relates to a structure of an LC circuit capable of reducing a chip area in an integrated circuit device.

[0002]

2. Description of the Related Art As a monolithic microwave integrated circuit (MMIC) that handles high-frequency signals in the microwave region or the like, a GaAs analog IC is usually used.
In such an analog IC, a capacitor C and an inductor L connected in series as shown in FIG. 4 are used in large quantities. The capacitor C and the inductor L are formed side by side on the surface of the semiconductor substrate, and occupy a large area on the surface of the semiconductor substrate even though no semiconductor layer is used. In particular, the capacitor C requires a large area to form a large capacitance, and the inductor L needs to increase the number of turns in order to obtain a large inductance. Therefore, forming a coil in a plane requires a large area. .

[0003]

In the conventional configuration in which the capacitors C and the inductors L are arranged side by side on the surface of the substrate, the ratio of the combined area of the capacitors to the entire circuit is very large, and the capacitors C and the inductors L exist. Was one of the causes of increasing the chip size.

Further, in a high-frequency circuit, even a small number of connecting lines may cause inductance, interact between wirings, pick up noise, and the like, which may have a bad effect, and the connecting wirings should be formed compactly. There is.

In view of the above circumstances, the present invention makes it possible to reduce the chip size and shorten the connection wiring.
It is intended to provide a circuit structure.

[0006]

The structure of the LC circuit of the present invention comprises a capacitor and an inductor which are provided above and below a substrate via an insulating film, and the capacitor and the inductor penetrate through the insulating film. It is characterized by being connected by the formed connection wiring.

In an analog IC, a capacitor and an inductor are rarely used independently of each other as shown in FIG. 4, and they are often connected in series and used integrally. That is, those connected in series are used as if they were one circuit element. The present invention has been made paying attention to such a point, and by arranging the capacitor and the inductor vertically or vertically on the substrate without arranging the capacitor and the inductor side by side, the capacitor or the inductor The area of the chip is reduced by occupying the substrate area only on one side.

[0008]

According to the present invention, since the inductor is formed through the insulating film by utilizing the flat portion of the capacitor forming portion, the area occupied by the substrate is greatly reduced. In this case, when the area of the capacitor is smaller than that of the inductor, the gap between the electrodes of the capacitor is increased to increase the electrode area, or the coil of the inductor is three-dimensionally formed with an insulating film between the flat portion. This is preferable from the viewpoint of being able to form an inductor and making the characteristics uniform.

[0009]

The structure of the LC circuit of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is an explanatory drawing of the manufacturing process of one embodiment of the structure of the LC circuit of the present invention.

First, as shown in FIG. 1A, G
The lower electrode 2 of the capacitor C is formed on the substrate 1 made of a compound semiconductor or the like in which a high frequency element such as aAs is formed. The material of the lower electrode 2 is A, which has a large electric conductivity.
Lift-off in which u, Ag, Cu, etc. can be used and is deposited on the entire surface by a vapor deposition method, a sputtering method or the like, and then patterned and etched, or the resist film is patterned in advance and removed together with an excess resist film. It can be formed by a method or the like.

Reference numeral 3 denotes Si provided on the lower electrode 2.
It is a dielectric film made of O ₂ , SiN _x , Al ₂ O ₃ , and the like. The dielectric film 3 can be manufactured by a thermal CVD method, a plasma CVD method, a sputtering method, or the like. Then, the upper electrode 4 made of the same material as the lower electrode 2 is formed on the dielectric film 3 to obtain the capacitor C (see FIG. 3).

Next, an insulating film 5 is formed on the obtained capacitor C by using the same material as the dielectric film 3 ((b) of FIG. 1). The insulating film 5 has unevenness at the end portion due to the steps of the upper electrode 4, the dielectric film 3, the lower electrode 2, etc., but is formed on the flat surface above the upper electrode 4.

Next, a contact hole or a via hole is formed in the insulating film 5, and a contact metal or a via metal is buried in the contact hole to form a connection wiring 6 (FIG. 1 (c)). As the contact metal, it is preferable to use a metal having a high electric conductivity like the material for the lower or upper electrode. The contact holes are formed, for example, by performing dry etching such as RIE or etching such as wet etching after forming the resist pattern. Then, the contact wiring 6 can be formed by burying a contact metal in the obtained hole by vapor deposition or the like and then removing the resist by lift-off.

Next, the inductor L is formed on the insulating film 5 so that the end portion 7 (see FIG. 2) is located on the connection wiring 6 ((d) of FIG. 1). As the material of the inductor L, Au, Ag, Cu or the like having a large electric conductivity can be used like the electrode of the capacitor. The inductor L is formed by (1) forming a resist pattern after vapor deposition of these materials, removing unnecessary portions by etching such as RIE, ion milling, wet etching, and then peeling the resist, or (2) resist After forming the pattern, the material can be vapor-deposited, and then the resist can be removed by lift-off to prepare the layer.

In the first embodiment shown in FIG. 1, the inductor L is planarly formed on the flat insulating film 5, but when it is desired to increase the number of turns of the coil, the insulating film is formed on the inductor material. You may make it form a three-dimensional form by further laminating a coil via. In this case, it is easy to form a three-dimensional inductor by using an insulating film such as polyimide whose surface is easily flattened or by stacking coils having the same shape as the first stage coil.

Although the terminal connection wiring of the inductor is drawn out through the uneven portion on the surface, this portion may be used for the purpose of connection only.

By using a compound semiconductor such as GaAs for the substrate 1 as described above, high-frequency FETs and diodes can be formed on the substrate, and a monolithic integrated circuit of the high-frequency circuit can be formed in a small chip size together with the LC circuit of the present invention. Can be made compact.

[0019]

As described above, in the structure of the LC circuit of the present invention, since the capacitors and the inductors are three-dimensionally arranged on the substrate, the chip area can be reduced. Moreover, because of the vertical connection, mutual connection wiring can be greatly reduced to around 1 to 2 μm compared to the conventional 10 μm or more, and mutual interference due to connection wiring and adverse effects on characteristics such as picking up noise can be largely prevented and small size Thus, a high-performance microwave monolithic integrated circuit can be obtained.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a manufacturing process of an embodiment of the structure of an LC circuit of the present invention.

FIG. 2 is a plan view of the inductor shown in FIG.

FIG. 3 is a plan view of the capacitor shown in FIG.

FIG. 4 is a circuit diagram of an example of a conventional analog IC.

[Explanation of symbols]

 1 Substrate 2 Lower Electrode 3 Dielectric Film 4 Upper Electrode 5 Insulating Film 6 Connection Wiring C Capacitor L Inductor

Claims (1)

[Claims] 1. A capacitor and an inductor provided above and below a substrate via an insulating film, and the capacitor and the inductor are connected by a connection wiring formed through the insulating film. The structure of the LC circuit.