JPH06177265A - Semiconductor device and fabrication thereof - Google Patents

Abstract

PURPOSE:To provide a semiconductor device in which short circuit can be prevented between a wiring and an overlying wiring irrespective of significant misalignment. CONSTITUTION:A first wiring 5 is formed through a gate oxide film 3 on a semiconductor substrate 1. A silicon nitride film 9 is formed on the first wiring 5 and a silicon oxide film 7a is formed on the side wall thereof. The silicon oxide 7a is covered by a silicon nitride film 11a. The silicon nitride film 11a is etched at a lower rate than the silicon oxide 7a. Consequently, the first wiring 5 is not exposed in a through hole 13 even if significant misalignment occurs at the time of photolithography.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device, and more particularly to a semiconductor device having a through hole on a side portion of a wiring film and a method for manufacturing the same.

[0002]

2. Description of the Related Art A method of manufacturing a semiconductor device having a structure in which a semiconductor substrate and an upper wiring are electrically connected through a through hole will be described below. As shown in FIG. 9, first wiring films 23 are formed on the semiconductor substrate 21 at intervals. A silicon oxide film 25 is formed on the semiconductor substrate 21 so as to cover the first wiring film 23. A resist 27 is formed on the silicon oxide film 25. Through holes are used to electrically connect the second wiring film (not shown in FIG. 9), which is the upper wiring, to the semiconductor substrate 21. The through holes are formed by using photolithography technology and etching technology.

A deviation inevitably occurs in the alignment of the photoengraving technique. Due to the miniaturization of semiconductor devices, the distance between the first wiring films 23 tends to be narrowed. For this reason, if the amount of misalignment is large, there may be a case where a part of the through hole 29 is located on the first wiring film 23 as shown in FIG.

The resist 27 is removed, and an aluminum film is formed on the silicon oxide film 25 as shown in FIG. The second wiring film 3 is formed by patterning the aluminum film.
1 is formed. Since a part of the through hole 29 is formed on the first wiring film 23, the second wiring film 31 and the first wiring film
The first wiring film 23 and the second wiring film 31 are short-circuited with each other.

[0005]

Since the conventional semiconductor device is configured as described above, a through hole is formed between the first wiring films and the contact between the second wiring film and the semiconductor substrate is formed. In such a case, if the amount of misalignment is large, a part of the through hole 29 may be located on the first wiring film 23 as shown in FIG. As a result,
As shown in 0, the second wiring film 31 and the first wiring film 23 were short-circuited.

The present invention has been made to solve the above-mentioned conventional problems. An object of the present invention is to provide a semiconductor device capable of preventing a short circuit between a wiring film and an upper wiring film located above the wiring film and a method of manufacturing the same, even if the amount of misalignment is large.

[0007]

A semiconductor device according to the present invention includes a wiring film formed on a semiconductor substrate, a sidewall silicon oxide film formed along a side wall of the wiring film, and a semiconductor film of the semiconductor substrate. Above the semiconductor substrate, the insulating film made of a material that is formed so as to cover the wiring film and the sidewall silicon oxide film and has a slower etching rate than the silicon oxide film when the silicon oxide film is etched. And a silicon oxide film formed so as to cover the insulating film. The insulating film is, for example, a silicon nitride film or an alumina film.

In the method of manufacturing a semiconductor device according to the present invention, when the conductive film is formed on the semiconductor substrate and the silicon oxide film is etched on the conductive film, the etching rate becomes slower than that of the silicon oxide film. A step of forming a first insulating film made of a material, a step of patterning the conductive film and the first insulating film to form a wiring film having a first insulating film on the upper side, and sidewall silicon on the side wall of the wiring film. A step of forming an oxide film, a step of covering the sidewall silicon oxide film, a step of forming a second insulating film made of a material having an etching rate slower than that of the silicon oxide film when the silicon oxide film is etched, And a step of forming a silicon oxide film so as to cover the second insulating film.

[0009]

A semiconductor device according to the present invention includes an insulating film formed on a semiconductor substrate so as to cover the wiring film and the sidewall silicon oxide film. The insulating film is made of a material whose etching rate is slower than that of the silicon oxide film when the silicon oxide film is etched. The insulating film is covered with a silicon oxide film. When a through hole exposing a semiconductor substrate is formed on this silicon oxide film by using photolithography and etching techniques, the wiring film is formed by etching the silicon oxide film even if the amount of misalignment is large. Since the wiring film is covered with the insulating film made of a material having a slower etching rate, the wiring film is not exposed in the through hole.

In the method of manufacturing a semiconductor device according to the present invention, when the silicon oxide film is etched, a wiring film is formed on which a first insulating film made of a material having an etching rate slower than that of the silicon oxide film is formed. Forming a sidewall silicon oxide film on the side wall of the wiring film, and covering the sidewall silicon oxide film, a second insulating film made of a material whose etching rate is slower than that of the silicon oxide film when the silicon oxide film is etched. Is forming. Therefore, the wiring film is covered with the first and second insulating films. Therefore,
When a through hole exposing a semiconductor substrate is formed in a silicon oxide film covering the first and second insulating films by using a photolithography technique and an etching technique, the wiring film is formed of the silicon oxide film even if the misalignment amount is large. Since the first and second insulating films made of a material having an etching rate slower than that of the silicon oxide film at the time of etching are covered, it is possible to prevent the wiring film from being exposed in the through hole.

[0011]

1 is a sectional view of a semiconductor device according to the present invention. A first wiring film 5 is formed on semiconductor substrate 1 with gate oxide film 3 interposed. First wiring film 5
A silicon nitride film 9 is formed on the above. The silicon nitride film is an insulating film made of a material having an etching rate slower than that of the silicon oxide film when etching the silicon oxide film. A sidewall silicon oxide film 7a is formed on the sidewall of the first wiring film 5. A sidewall silicon nitride film 11a is formed so as to cover the sidewall silicon oxide film 7a.

A silicon oxide film 15 is formed on semiconductor substrate 1 so as to cover sidewall silicon oxide film 11a and silicon nitride film 9. Through holes 1 for exposing the semiconductor substrate 1 are formed in the silicon oxide film 15.
3 is formed. A second layer is formed on the silicon oxide film 15.
Wiring film 17 is formed. The second wiring film 17 is electrically connected to the semiconductor substrate 1 via the through hole 13.

Since the silicon nitride film 9 covering the first wiring film 5 and the sidewall silicon nitride film 11a are materials whose etching rate is slower than that of the silicon oxide film when the silicon oxide film is removed by etching, the silicon oxide film 15
When the through hole 13 is formed in the through hole 13, the first wiring film 5 is not exposed in the through hole 13 even if the amount of misalignment is large. Therefore, it is possible to prevent a short circuit between the first wiring film 5 and the second wiring film 17.

A method of manufacturing the semiconductor device according to the present invention shown in FIG. 1 will be described below. As shown in FIG. 2, a gate oxide film 3 is formed on the semiconductor substrate 1 by thermal oxidation. A polycrystalline silicon film and a silicon nitride film are sequentially formed on the gate oxide film 3 by the CVD method. The polycrystal silicon film and the silicon nitride film are patterned by using the photoengraving technique and the etching technique to form the first wiring film 5 on which the silicon nitride film 9 is formed.

As shown in FIG. 3, a silicon oxide film 7 is formed on the semiconductor substrate 1 by the CVD method so as to cover the first wiring film 5.

As shown in FIG. 4, the silicon oxide film 7 is etched by anisotropic etching to form a sidewall silicon oxide film 7a on the side wall of the first wiring film 5.
The anisotropic etching is continued until the side surface 9a of the silicon nitride film 9 is exposed.

As shown in FIG. 5, a silicon nitride film 11 is formed on the semiconductor substrate 1 so as to cover the sidewall silicon oxide film 7a and the silicon nitride film 9 by the CVD method.

As shown in FIG. 6, the silicon nitride film 11 is etched by anisotropic etching to form a sidewall silicon nitride film 11a. Since the side wall silicon oxide film 7a is etched until the side surface 9a of the silicon nitride film 9 is exposed, the side wall silicon oxide film 7a is formed when the side wall silicon nitride film 11a is formed.
It is not exposed a.

As shown in FIG. 7, a silicon oxide film 15 is formed on the entire surface of the semiconductor substrate 1 by the CVD method. A resist 18 is applied on the silicon oxide film 15. The resist 18 is selectively exposed / developed and patterned by using photolithography. There is a large amount of misalignment,
The opening 18a of the resist 18 is located on the first wiring film 5.

As shown in FIG. 8, the silicon oxide film 15 is selectively etched using the resist 18 as a mask to form a through hole 13 for exposing the semiconductor substrate 1. Even if the amount of misalignment is large, the etching rate of the silicon nitride film is slow, and therefore the first wiring film 5 is not exposed in the through hole 13 and the semiconductor substrate 1 is self-aligned.
Can be exposed. FIG. 1 shows a state in which the resist 18 is removed and the second wiring film 17 made of aluminum is formed on the silicon oxide film 15.

In this embodiment, the silicon nitride film is used as the first insulating film made of a material having an etching rate slower than that of the silicon oxide film when etching the silicon oxide film, but an alumina film may be used.

[0022]

The semiconductor device according to the present invention has the insulating film formed on the semiconductor substrate so as to cover the wiring film and the sidewall silicon oxide film.
The insulating film is made of a material whose etching rate is slower than that of the silicon oxide film when etching the silicon oxide film. The insulating film is covered with a silicon oxide film. When using photolithography and etching technology to form through holes in this silicon oxide film to expose the semiconductor substrate, prevent the wiring film from being exposed in the through holes even if the amount of misalignment is large. You can Therefore, it is possible to prevent a short circuit between the wiring film and the upper wiring film above the wiring film and improve the reliability of the semiconductor device.

In the method of manufacturing a semiconductor device according to the present invention, a wiring film is formed on which a first insulating film made of a material whose etching rate is slower than that of a silicon oxide film when the silicon oxide film is etched is formed. Then, a sidewall silicon oxide film is formed on the side wall of the wiring film, and the second insulating film made of a material whose etching rate is slower than that of the silicon oxide film when etching the silicon oxide film so as to cover the sidewall silicon oxide film. Forming a film. Therefore, the wiring film can be covered with the first and second insulating films. Therefore, when a through hole exposing the semiconductor substrate is formed in the silicon oxide film covering the first and second insulating films by using the photoengraving technique and the etching technique, the wiring film is formed in the through hole even if the misalignment amount is large. Can be prevented from being exposed. Therefore, it is possible to prevent a short circuit between the wiring film and the upper layer wiring film formed on the wiring film, and improve the reliability of the semiconductor device.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of a semiconductor device according to the present invention.

FIG. 2 is a sectional view of a first step of a manufacturing method of an embodiment of the semiconductor device according to the present invention.

FIG. 3 is a sectional view of a second step of the method for manufacturing the semiconductor device according to the embodiment of the present invention.

FIG. 4 is a sectional view of a third step of the method for manufacturing the semiconductor device according to the embodiment of the present invention.

FIG. 5 is a sectional view of a fourth step of the method for manufacturing the semiconductor device according to the embodiment of the present invention.

FIG. 6 is a cross sectional view of a fifth step of the manufacturing method for the embodiment of the semiconductor device according to the present invention.

FIG. 7 is a cross sectional view of a sixth step of the method for manufacturing the semiconductor device according to the embodiment of the present invention.

FIG. 8 is a cross sectional view of a seventh step of the manufacturing method for the embodiment of the semiconductor device according to the present invention.

FIG. 9 is a sectional view of a first step of the conventional method for manufacturing a semiconductor device.

FIG. 10 is a cross-sectional view of a second step of the conventional method for manufacturing a semiconductor device.

[Explanation of symbols]

 1 Semiconductor Substrate 5 First Wiring Film 7a Sidewall Silicon Oxide Film 9 Silicon Nitride Film 11a Sidewall Silicon Nitride Film 15 Silicon Oxide Film

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location H01L 29/784

Claims (3)

[Claims] 1. A wiring film formed on a semiconductor substrate, a sidewall silicon oxide film formed along a side wall of the wiring film, and the wiring film and the side film on the semiconductor substrate. An insulating film made of a material that is formed so as to cover the wall silicon oxide film and has an etching rate slower than that of the silicon oxide film when the silicon oxide film is etched; and an insulating film that covers the insulating film on the semiconductor substrate. And a silicon oxide film formed on the semiconductor device. 2. The semiconductor device according to claim 1, wherein the insulating film includes a silicon nitride film or an alumina film. 3. A step of forming a conductive film on a semiconductor substrate, and a step of forming a first insulating film on the conductive film, the first insulating film made of a material having an etching rate slower than that of the silicon oxide film when etching the silicon oxide film. And a step of patterning the conductive film and the first insulating film to form a wiring film having the first insulating film thereon, and forming a sidewall silicon oxide film on a sidewall of the wiring film. Forming a second insulating film made of a material having an etching rate slower than that of the silicon oxide film when etching the silicon oxide film so as to cover the sidewall silicon oxide film; A method of manufacturing a semiconductor device, comprising: forming a silicon oxide film so as to cover the insulating film.