JPH0661422A - Semiconductor integrated circuit device - Google Patents

Abstract

PURPOSE:To make a semiconductor integrated circuit device small by a method wherein a capacitor for a transmission circuit element formed in the semiconductor integrated circuit device or the like is formed as a structure by which a high capacitance can be obtained in a very small area. CONSTITUTION:Two electrode walls 6a, 6b extended to directions perpendicular to a substrate 2 are arranged in parallel on the substrate so as to keep a certain interval, a dielectric film 7 is arranged between the two electrode walls, the circumference of the two electrode walls is protected by a protective film 4, and connecting interconnections 3a, 3b for connection use are connected to the electrode walls. Thereby, a capacitor 1 is formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a capacitor, a manufacturing method thereof, and a semiconductor integrated circuit device using the capacitor. More specifically, the present invention relates to a capacitor in which the structure of the capacitor is three-dimensionally formed to reduce the area, a manufacturing method thereof, and a semiconductor integrated circuit device.

[0002]

2. Description of the Related Art Conventionally, as a high frequency semiconductor integrated circuit device, a high frequency field effect transistor (hereinafter referred to as FET) is formed on a semiconductor substrate, and a monolithic microwave having an inductor and a capacitor formed on the substrate. An integrated circuit device (hereinafter referred to as MMIC) is used.

In this MMIC, of the transmission circuit elements formed on the surface of the substrate, the capacitors have the structure shown in FIGS. 4 to 5, a first metal film 33 serving as one electrode is formed on a semiconductor substrate 32 made of gallium arsenide (GaAs) or the like, a dielectric film 34 is provided on the entire surface of the first metal film 33, and the other is further formed thereon. The second metal film 35 that serves as the electrode is provided to manufacture the capacitor 31.

[0004]

[Problems to be Solved by the Invention] Capacitor 31
The interval between both electrodes is formed to be close to the limit in terms of withstand voltage, and in order to increase the capacitance, the facing area between the first metal film 33 and the second metal film 35 is formed to be large. There is a need. However, when the facing area is increased, a large area on the surface of the substrate 32 is occupied by the capacitor. For this reason, it becomes difficult to reduce the size of the MMIC, and accordingly it becomes difficult to reduce the cost.

It is an object of the present invention to provide a transmission circuit element which solves such a problem and which can obtain a large capacity in a small area.

[0006]

The capacitor of the present invention comprises:
Two electrode walls extending in a direction perpendicular to the substrate are arranged in parallel on the substrate with a constant gap, and a dielectric film is arranged between the two electrode walls. It is characterized in that a connection wiring and a protective film which are respectively connected to the electrode walls are formed on the side opposite to the dielectric film.

The method of manufacturing the capacitor of the present invention is (a)
A connection wiring having a constant gap is formed on the substrate before or after the protection film is provided or during the formation of the protection film or after the protection film is provided. Forming two etching grooves in the protective film in a direction perpendicular to the protective film so as to pass through the respective end portions of
(c) A metal material is laminated on the etching groove to form an electrode wall.

The semiconductor integrated circuit device of the present invention is a semiconductor integrated circuit device comprising an active element formed on a semiconductor substrate and a transmission circuit element including a capacitor formed on the surface of the substrate, the surface of the substrate At least one capacitor formed in the above is the capacitor according to claim 1.

[0009]

According to the present invention, the capacitor has the electrode walls of the capacitor formed vertically on the surface of the substrate, and the dielectric film is arranged between the two electrode walls. Since a protective film is formed on the side opposite to the connection wiring,
In order to form a capacitor having a large capacity, it can be formed by laminating electrode walls and a dielectric film between them on the surface side. Therefore, it is possible to form a capacitor having a desired capacitance with a constant occupation area on the substrate surface.

Further, according to the manufacturing method of the present invention, the dielectric film between the electrode films and the outer protective film are formed of the same material, and then the electrode film forming place is etched to form an etching groove, Since the metal material used for the electrode walls is formed by vapor deposition or sputtering, thin film formation techniques such as CVD, vapor deposition, and sputtering can be combined with photolithography as in the case of manufacturing ordinary semiconductor devices. Easy to make.

Further, according to the semiconductor integrated circuit device of the present invention, a large-capacity capacitor can be three-dimensionally formed in a small area,
A small semiconductor integrated circuit device can be obtained.

[0012]

The present invention will be described below with reference to the drawings. 1 is a cross-sectional explanatory view showing a capacitor portion which is an embodiment of the present invention, FIG. 2 is a plan layout view showing a main portion of a high frequency amplifier circuit having the capacitor of FIG. 1, and FIG. 3 is an equivalent circuit diagram of FIG. Is.

The structure of the capacitor 1 which is a constituent element of the semiconductor integrated circuit device of the present invention will be described with reference to FIG. For example, on the semiconductor substrate 2 made of gallium arsenide (GaAs) or the like, connection wirings 3a, 3b made of two layers of Ti / Au
Are formed. The connection wirings 3a and 3b have a gap A formed by removing a portion corresponding to a portion between electrode walls where a capacitor is to be formed. Si on its surface
A protective film 4 made of O ₂ , SiN, SiON or the like is formed. Furthermore, the gap A between the connection wirings 3a and 3b
Ti that is connected to the end part that forms the
Electrode walls 6a and 6b made of / Au or the like are formed. The electrode walls 6a and 6b are respectively connected to the end portions of the above-mentioned connection wirings 3a and 3b, and are connected to other elements as electrode terminals or led out to the outside. As a result, the dielectric film 7 formed as a protective film is disposed between the electrode walls 6a and 6b, and the capacitor 1 is formed by the electrode walls 6a and 6b and the dielectric film 7. .

The capacitor 1 constructed as above is
Since the opposing electrode walls 6a and 6b are formed in the vertical direction, the area occupied by the surface of the semiconductor substrate 2 is extremely small. Moreover, in order to increase the capacitance, even when the electrode wall is formed large, it is possible to form a large-capacity capacitor formed in a vertical direction with respect to the substrate and having a minute area.

In the above example, the connection wirings 3a and 3b are formed directly on the semiconductor substrate 2, but the electrode walls 6a,
It may be formed in the protective film 4 or may be formed on the surface of the protective film 4 as long as it is connected to each of 6b. Further, although the example of forming the capacitor on the semiconductor substrate has been described, the capacitor may be formed on the insulating substrate when it is not necessary to form the semiconductor element.

Further, in order to make the device three-dimensional, a multilayer structure circuit can be easily manufactured by further forming an interlayer insulating film on the electrode walls 6a and 6b to form another transmission circuit device. be able to.

With the above-described structure, for example, a capacitor having a height of electrode wall of about 5 μm, a width of 100 μm and an interval of 1 μm and a thickness of 0.025 pF can be formed.

Next, a method for manufacturing the capacitor 1 of the present invention will be described.

First, a protective film is provided on the substrate, and before the protective film is provided, during the process of providing the protective film, or after the protective film is provided, connection wirings having a constant gap are formed. Specifically, a metal film having a Ti / Au two-layer structure or the like is formed on a semiconductor substrate 2 made of gallium arsenide (GaAs) by 0.01 to 0.1 μm, 0.5 to 2 μm, or by a vapor deposition or sputtering method. The connection wirings 3a and 3b are etched by the photolithography process to form the gap A.
Are formed so as to face each other. Si on its surface
CVD of a protective film 4 made of O ₂ , SiN, SiON, etc.
Method or sputtering method. The thickness of this protective film is determined by the area corresponding to the capacitance of the capacitor to be formed, but is usually 2 to 10 μm and the width (length in the direction perpendicular to the drawing) is 1 to 5 μm.

In this specific example, the connection wiring 3 is formed on the semiconductor substrate.
Although the example of forming the protective film after forming a and 3b has been described, the connection wirings 3a and 3b may be formed during the deposition of the protective film 4, or the protective film 4 may be finished. It may be formed on the surface of the protective film 4.

Next, two etching grooves are formed in the protective film in the direction perpendicular to the protective film so as to pass through the ends of the connection wirings which face each other at a constant gap. As a specific example, an etching groove is formed at a place where an electrode wall is formed by patterning with a photomask and performing plasma etching. The distance between the two etching grooves is the thickness of the dielectric film of the capacitor, and is an important dimension for determining the capacitance of the capacitor together with the area. Moreover, the above-mentioned connection wiring 3a,
The edge of 3b is formed so as not to enter the dielectric film sandwiched by the etching grooves. The width of the dielectric film sandwiched between the etching grooves is usually formed to be about 1 μm, but it depends on the relative dielectric constant of the dielectric film used and the desired capacitance of the capacitor.

Next, an electrode wall is provided by laminating a metal material on the etching groove. As a specific example, when the connection wirings 3a and 3b formed on the substrate remain, a Ti film is formed on the connection wirings 3a and 3b by 0.01-
0.1 μm, and then an Au film is laminated up to the surface of the protective film by vapor deposition, sputtering or plating. When the thickness (height) of the electrode walls to be laminated is large (high), the plating method can form a desired thickness in 1/4 time as compared with the vapor deposition method. That is, it takes about 2 hours for the plating method, 5 hours for the sputtering method, and 8 hours for the vapor deposition method to form the electrode wall having a thickness of 3 μm.

By laminating the metal material so as to fill the etching groove in this manner, a capacitor having electrode walls 6a and 6b on both sides of the dielectric film 7 is formed.

Next, an example in which a high-frequency amplifier circuit including the capacitor 1 configured as above is manufactured will be shown.

As shown in FIGS. 2 and 3, in a high frequency amplifier circuit used for a high frequency amplifier or the like, FETs 8 and 12 are formed as active elements on a semiconductor substrate, and a first stage amplification FET is used.
The gate electrode 9 of 8 is electrically connected to the first terminal 10,
The drain electrode 11 is electrically connected to the electrode wall 6a of the capacitor 1 forming the inter-stage capacitance, the gate electrode 13 of the amplification FET 12 is electrically connected to the vertical electrode wall 6b of the capacitor 1, and the drain electrode 14 is 2 is electrically connected to the terminal 15 of the FET 2, and further includes the source electrode 16 of the FET 8 and the FET 12
Source electrodes 17 are electrically connected to ground terminals 18, respectively. Also, the first and second terminals 1
DC cut capacitors 19 and 20 are connected in series on the input terminal 27 and output terminal 28 sides of 0 and 15, respectively, and the first bias terminal 23 and the second bias are connected via inductors 21 and 22. A terminal 24 is formed so that a DC bias can be supplied. In addition, FET12
A DC bias terminal 26 is formed on the gate electrode 13 via the inductor 25 (see FIG. 3).

This semiconductor integrated circuit device has a capacitor 1
Is arranged in a smaller area than the conventional one,
The entire circuit is miniaturized.

[0027]

According to the present invention, the capacitor is formed by forming the electrode wall of the capacitor in the direction perpendicular to the surface of the substrate and arranging the dielectric film therebetween to form the capacitor. Even if the area of the electrode wall is increased, the area of the substrate surface does not change only by extending upward, and a large capacitance can be obtained with a minute area.

Further, a high frequency element such as an FET is formed on a semiconductor substrate, and a capacitor formed on the surface of the substrate is formed by the capacitor of the present invention, whereby a monolithic microwave integrated circuit device having a small chip area can be formed. . Furthermore, as a result of the smaller element area, the wiring connecting the elements is shortened, mutual interference and noise generation in the wiring that tends to occur in the microwave band can be suppressed, and a monolithic microwave integrated circuit device with high characteristics can be obtained. You can

Further, with the miniaturization of the device, it is possible to cope with the recent miniaturization of electronic equipment and to contribute to cost reduction.

[Brief description of drawings]

FIG. 1 is a cross-sectional explanatory view showing a capacitor portion of a transmission circuit element that is an embodiment of the present invention.

FIG. 2 is a plan layout view showing a main part of an embodiment of a semiconductor integrated circuit.

FIG. 3 is an equivalent circuit diagram of FIG.

FIG. 4 is a plan view showing a structure of a conventional capacitor.

5 is a cross-sectional view taken along line VV of the capacitor of FIG.

[Explanation of symbols]

 1 Capacitor 2 Semiconductor Substrate 3a, 3b Connection Wiring 4 Protective Film 6a, 6b Electrode Wall 7 Dielectric Film

Claims (3)

[Claims] 1. Two electrode walls extending in a direction perpendicular to the substrate are arranged in parallel on a substrate with a constant gap, and a dielectric film is arranged between the two electrode walls. A capacitor formed by forming a connection wire and a protective film, which are connected to the electrode wall, respectively, on a side of the electrode wall opposite to the dielectric film. 2. (a) A protective film is provided on a substrate, and a connection wiring having a constant gap is formed before the protective film is provided, during the process of providing the protective film, or after the protective film is provided, and (b) the connection. Two etching grooves are formed in the protective film in a direction perpendicular to the ends of the wiring so as to pass through opposite ends at a constant gap, and (c) a metal material is laminated on the etching grooves to form an electrode wall. A method of manufacturing a capacitor characterized by: 3. A semiconductor integrated circuit device comprising an active element formed on a semiconductor substrate and a transmission circuit element including a capacitor formed on the surface of the substrate, wherein at least one capacitor formed on the surface of the substrate. A semiconductor integrated circuit device comprising the capacitor according to claim 1.