JP2828135B2 - MIM capacitor and manufacturing method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an MIM (metal film / insulating film / metal film) capacitor having an air bridge and used in a semiconductor integrated circuit device or the like, and a method of manufacturing the same.

[0002]

2. Description of the Related Art First, an MI having a conventional air bridge.
An M capacitor and a method for manufacturing the same will be described with reference to the drawings.

FIGS. 4A to 4D are plan views showing steps of manufacturing a conventional MIM capacitor. FIG.
(D) is a view showing a manufacturing process of the MIM capacitor having an air bridge in a cross section taken along the line AA 'shown in FIG. 4 (d), and FIGS. 6 (a) to 6 (d) are FIGS. B- shown
It is a figure showing a manufacturing process of a MIM capacitor which has an air bridge in the section of the B 'line.

First, a lower electrode 3 is formed on an insulating film 2 on a semiconductor substrate 1 by a lift-off method or the like. afterwards,
On the lower electrode 3, SiO ₂ ,
A capacitance insulating film 4 of Si ₃ N ₄ or the like is formed. At this time, a thinned portion 8 having a thin capacitive insulating film is often formed at the end of the lower electrode 3 (FIGS. 4A, 5B, and 6A).

Next, after forming an air bridge photoresist 9 patterned by leaving the air bridge portion by a usual lithography technique, a plating metal thin film 5 made of Au or the like is formed on the entire surface by about 0.3 μm by sputtering or the like. 4 (b), 5 (b) and 6
(B)).

Next, after a plating photoresist 10 having an opening in the upper electrode portion is formed by a usual lithography process, the upper electrode 6 made of Au or the like is formed to a thickness of 2 μm by electroplating using the metal thin film 5 for plating as a conductive layer. 4 (c), 5 (c) and 6
(C)).

Next, after removing the plating photoresist 9 with a solvent, the plating metal thin film 5 is etched by ion milling using Ar ions or the like. Finally, the air bridge photoresist 9 is removed with a solvent. At the time of this ion milling, along the peripheral edge of the upper electrode 6, the ion milling flaw 1 in which the capacitive insulating film is dug is formed.
1 (FIG. 4 (d), FIG. 5 (d),
And FIG. 6 (d)).

The M having such an air bridge
An example of the IM capacitor is described in, for example, Japanese Patent Application Laid-Open No. Hei 5-3403.

[0009]

By the way, the above-mentioned MI
The M capacitor has a problem that dielectric breakdown is likely to occur due to the following two factors.

When the metal thin film for plating is patterned by ion milling, ion milling flaws in which a capacitive insulating film is dug shallowly along the peripheral edge of the upper electrode are formed.
At this point, electric field concentration occurs and dielectric breakdown occurs.

At the end of the lower electrode, a thinned portion in which the capacitance insulating film is thinned is apt to be formed, and electric field concentration occurs here, causing dielectric breakdown.

In a conventional MIM capacitor having an air bridge, as shown in the drawing, an air bridge wiring having gas 7 immediately below the upper wiring at the intersection of the lower electrode and the upper electrode is used to form the lower electrode end. To prevent dielectric breakdown due to electric field concentration. However, dielectric breakdown due to the milling scratches 11 cannot be prevented.

An object of the present invention is to reduce the thickness of the capacitor insulating film at the end of the lower electrode and to prevent the dielectric breakdown voltage from deteriorating due to ion milling flaws without increasing the number of steps.
An object of the present invention is to provide an M capacitor and a method for manufacturing the same.

[0014]

According to the present invention, there is provided an MIM capacitor comprising an insulating film on a semiconductor substrate or a lower electrode formed on a surface of a semi-insulating semiconductor substrate; a capacitor insulating film formed on the lower electrode; A plating metal thin film formed on the capacitance insulating film, and an upper electrode formed on the plating metal thin film, and an air bridge wiring is provided at an intersection of an end of the lower electrode and the upper electrode. The used MIM capacitor is characterized in that a peripheral edge of the upper electrode is lifted so that the peripheral edge of the upper electrode does not directly contact the capacitance insulating film.

The method of manufacturing a MIM capacitor according to the present invention includes a first step of forming a lower electrode on an insulating film on a semiconductor substrate or a surface of a semi-insulating semiconductor substrate, and a step of forming a capacitor insulating film on the lower electrode. A second step of forming, a third step of patterning a first photoresist for forming an air bridge on the capacitive insulating film, and a plating step on the entire surface of the capacitive insulating film and the first photoresist. A fourth step of forming a metal thin film, a fifth step of patterning a second photoresist for forming an upper electrode on the metal thin film, and a sixth step of forming an upper electrode on the metal thin film A MIM capacitor manufacturing method, comprising: a step of removing the second photoresist, the metal thin film, and the first photoresist sequentially.
Is patterned along the intersection between the edge of the lower electrode and the upper electrode and along the edge of the upper electrode.

As described above, in the present invention, the photoresist which has been used for forming the air bridge is not only used at the intersection of the edge of the lower electrode and the upper electrode but also along the edge of the upper electrode. Patterning. Therefore, when the metal thin film for plating is removed by ion milling, the photoresist protects the capacitive insulating film from ions of ion milling, so that ion milling scratches do not occur. As a result,
Deterioration of dielectric breakdown voltage can be prevented. In addition, since a photoresist used for forming an air bridge is used, the number of steps is not increased.

[0017]

Next, the present invention will be described with reference to the drawings.

FIGS. 1A to 1D show an MIM according to the present invention.
It is a top view showing an example of a manufacturing process of a capacitor. FIG.
FIGS. 3A to 3D are diagrams showing a manufacturing process of an MIM capacitor having an air bridge in a cross section taken along the line AA ′ shown in FIG. 1D, and FIGS. M having an air bridge in the section taken along the line BB 'shown in FIG.
It is a figure showing a manufacturing process of IM capacitor.

First, a lower electrode 3 is formed on an insulating film 2 on a semiconductor substrate 1 by a lift-off method or the like. After that, SiO ₂ or S
A capacitor insulating film ₄ such as i ₃ N ₄ is formed (FIGS. 1A, 2A, and 3A).

Next, the photoresist 9 for the air bridge 9 which is opened leaving the peripheral edge of the air bridge portion and the upper electrode 9 is formed.
Is formed by a usual lithography process, and a plating metal thin film 5 made of Au or the like is formed on the entire surface by about 0.3 μm by sputtering or the like (FIG. 1B, FIG. 2).
(B) and FIG. 3 (b)).

Next, a plating photoresist 10 having an opening in the upper electrode portion is formed by a usual lithography process, and then the upper electrode 6 made of Au or the like is formed to a thickness of 2 μm by electrolytic plating or the like using the plating metal thin film 5 as a conductive layer. 1 (c), 2 (c) and 3
(C)).

Next, after removing the plating photoresist 9 with a solvent, the plating metal thin film 5 is etched by ion milling using Ar ions. Finally, the air bridge photoresist 9 is removed with a solvent. (FIG. 1 (d), FIG. 2 (d), and FIG. 3 (d)).

[0023]

As described above, in the MIM capacitor and the method of manufacturing the same according to the present invention, the photoresist conventionally used for forming the air bridge is reduced only at the intersection between the end of the lower electrode and the upper electrode. Instead, patterning is performed along the upper electrode. Therefore, when the metal thin film for plating is removed by ion milling, the photoresist protects the capacitive insulating film from ions of ion milling, so that ion milling scratches do not occur. Therefore, there is an effect that deterioration of the dielectric breakdown voltage can be prevented.

Further, since the photoresist used for forming the air bridge is used, there is an effect that the number of steps is not increased.

[Brief description of the drawings]

FIG. 1 is a plan view showing an example of a method for manufacturing an MIM capacitor according to the present invention in the order of steps.

FIG. 2 is a cross-sectional view (a cross-sectional view along the line AA ′ shown in FIG. 1) illustrating an example of a method for manufacturing the MIM capacitor according to the present invention in the order of steps.

FIG. 3 is a cross-sectional view (a cross-sectional view taken along the line BB ′ shown in FIG. 1) illustrating an example of a method for manufacturing an MIM capacitor according to the present invention in the order of steps;

FIG. 4 is a plan view showing a process order of a conventional MIM capacitor manufacturing method.

FIG. 5 is a cross-sectional view (cross-sectional view taken along the line AA ′ shown in FIG. 4) for explaining the order of steps in the method of manufacturing the conventional MIM capacitor.
It is.

FIG. 6 is a cross-sectional view (a cross-sectional view taken along the line BB 'shown in FIG. 4) for explaining a process order of a conventional method for manufacturing an MIM capacitor.
It is.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Semiconductor substrate 2 Insulating film 3 Lower electrode 4 Capacitive insulating film 5 Metal thin film for plating 6 Upper electrode 7 Gas 8 Thinning part 9 Photoresist for air bridge 10 Photoresist for plating 11 Ion milling flaw

Claims (3)

(57) [Claims] An insulating film on the semiconductor substrate or a lower electrode formed on the surface of the semi-insulating semiconductor substrate; a capacitive insulating film formed on the lower electrode; and a plating formed on the capacitive insulating film. And a metal thin film for plating, and an upper electrode formed on the metal thin film for plating, wherein an air bridge wiring is used at an intersection between an end of the lower electrode and the upper electrode.
An MIM capacitor comprising an M capacitor having a prevention structure for preventing direct contact between a peripheral edge of the upper electrode and the capacitance insulating film. A first step of forming a lower electrode on an insulating film on a semiconductor substrate or a surface of a semi-insulating semiconductor substrate; a second step of forming a capacitor insulating film on the lower electrode; A third step of patterning a first photoresist for forming an air bridge on the insulating film, and a fourth step of forming a metal thin film for plating on the entire surface of the capacitive insulating film and the first photoresist. A fifth step of patterning a second photoresist for forming an upper layer electrode on the metal thin film, a sixth step of forming an upper layer electrode on the metal thin film, A seventh step of sequentially removing the metal thin film and the first photoresist;
Wherein the first photoresist is patterned along the intersection between the end of the lower electrode and the upper electrode and along the end of the upper electrode. Characteristic MI
A method for manufacturing an M capacitor. 3. The method of manufacturing an MIM capacitor according to claim 1, wherein said metal thin film is removed by ion milling.