Information
-
Patent Grant
-
6770557
-
Patent Number
6,770,557
-
Date Filed
Thursday, April 25, 200222 years ago
-
Date Issued
Tuesday, August 3, 200420 years ago
-
Inventors
-
Original Assignees
-
Examiners
Agents
- McDermott Will & Emery LLP
-
CPC
-
US Classifications
Field of Search
US
- 438 396
- 438 253
- 438 241
- 438 626
- 438 631
- 438 632
- 438 637
- 438 645
- 438 627
- 438 633
-
International Classifications
-
Abstract
In order to provide a method of fabricating a semiconductor device improved to be capable of attaining high reliability of wiring, a plug material is deposited on a semiconductor substrate to fill up a contact hole. The plug material is etched back thereby forming a plug in the contact hole. The surface of a cavity defined in the plug is covered with an insulator film. A metal wire is formed on the interlayer isolation film to be in contact with the plug.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to a method of fabricating a semiconductor device, and more specifically, it relates to a method of fabricating a semiconductor device improved to be capable of attaining high reliability in junction between a plug part and a wire part. The present invention also relates to a semiconductor device obtained by such a method.
2. Description of the Prior Art
FIG. 9
is a sectional view showing an ideally formed conventional dynamic random access memory.
A capacitor
11
is formed on a semiconductor substrate
50
. A metal wire
5
and lower conductor films
6
are connected with each other through plugs
3
embedded in contact holes
10
. The height of the capacitor
11
tends to increase due to high integration. Consequently, the contact holes
10
tend to increasingly deepen. The contact holes
10
are 0.3 μm to 0.4 μm in diameter, for example, and 1.5 μm to 2 μm in depth.
A fabrication process for a conventional semiconductor element such as the dynamic random access memory is described. In order to form contactors for the metal wire
5
and the lower conductor films
6
by the tungsten plugs
3
or the like, the contact holes
10
are first formed in an interlayer isolation film. Thereafter tungsten employed as the plug material is deposited and totally dryly etched back so that unnecessary tungsten part is removed, thereby forming the plugs
3
. Thereafter the metal wire
5
is formed on the plugs
3
as such.
If the dynamic random access memory is not ideally formed as shown in
FIG. 9
but any contact hole
10
is filled up with a plug material
2
as shown in
FIG. 10
, however, a cavity
20
may be defined in the plug material
2
.
When the plug material
2
having such a cavity
20
is etched back, the cavity
20
remains in the plug
3
as shown in FIG.
11
.
Referring to
FIG. 12
, when a portion located on such a cavity
20
is not covered with the metal wire
5
, i.e., when coverage is defective, a chemical solution (e.g., an organic solvent) employed in a wet step (a development step, a resist removal step or the like) for forming the metal wire
5
may penetrate into the cavity
20
to corrode the plug
3
. This problem remarkably arises when the metal wire
5
is misregistered.
The metal wire
5
and the plug
3
may not come into contact with each other due to such corrosion, leading to reduction of reliability of wiring. Further, the plug
3
may dissolve in the chemical solution and disappear, to reduce reliability of wiring.
SUMMARY OF THE INVENTION
The present invention has been proposed in order to solve the aforementioned problems, and an object thereof is to provide a method of fabricating a semiconductor device improved to be capable of attaining excellent contact between a metal wire and a plug thereby improving reliability of wiring.
Another object of the present invention is to provide a method of fabricating a semiconductor device improved to cause no disappearance of a plug.
Still another object of the present invention is to provide a semiconductor device improved in reliability of wiring, obtained by such a method.
In the method of fabricating a semiconductor device according to the present invention, an interlayer isolation film is first formed on a semiconductor substrate. A contact hole is formed in the aforementioned interlayer isolation film. A plug material is formed on the aforementioned semiconductor substrate to fill up the aforementioned contact hole. The aforementioned plug material is etched back thereby forming a plug in the aforementioned contact hole. The surface of a cavity defined in the aforementioned plug is covered with an insulator film. A metal wire is formed on the aforementioned interlayer isolation film to be in contact with the aforementioned plug.
According to a preferred mode of the present invention, the step of covering the surface of the cavity defined in the aforementioned plug with the insulator film includes a step of completely filling up the cavity formed in the aforementioned plug with the insulator film.
Alternatively, the step of covering the surface of the cavity defined in the aforementioned plug with the insulator film includes a step of covering the surface of the cavity without completely filling up the cavity formed in the aforementioned plug with the aforementioned insulator film.
The aforementioned insulator film preferably includes an SiN film.
This method is preferably applied to a method of fabricating a dynamic random access memory.
A semiconductor device according to another aspect of the present invention comprises a semiconductor substrate. An interlayer isolation film is formed on the aforementioned semiconductor substrate. A contact hole is formed in the aforementioned interlayer isolation film. A plug is formed in the aforementioned contact hole. The surface of a cavity defined in the aforementioned plug is covered with an insulator film. A metal wire is provided on the aforementioned interlayer isolation film to be in contact with the aforementioned plug.
According to a preferred mode of the present invention, the aforementioned insulator film completely fills up the aforementioned cavity.
According to another preferred mode of the present invention, the aforementioned insulator film does not completely fill up the aforementioned cavity
The aforementioned insulator film preferably includes an SiN film.
This semiconductor device includes a dynamic random access memory.
The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 1
to
5
are sectional views of a semiconductor device showing first to fifth steps in a method of fabricating a semiconductor device according to a first embodiment o the present invention;
FIG. 6
is a plan view of the semiconductor device shown in
FIG. 5
;
FIG. 7
is a plan view of the semiconductor device shown in
FIG. 5
causing misregistration;
FIG. 8
is a sectional view of a semiconductor device according to a second embodiment of the present invention;
FIG. 9
is a sectional view showing an exemplary semiconductor device to which the present invention is applied; and
FIGS. 10
to
12
are sectional views of a semiconductor device showing first to third steps in a conventional method of fabricating a semiconductor device.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Embodiments of the present invention are now described with reference to the drawings.
First Embodiment
A first embodiment of the present invention relates to a method of forming a contactor for a metal wire and a lower conductive layer through the following process:
Referring to
FIG. 1
, a contact hole
10
is formed in an interlayer isolation film (oxide film)
1
formed on a semiconductor substrate (not shown). The contact hole
10
is employed for forming a contactor for a metal wire
5
and a lower conductor layer. A plug material
2
is deposited on the semiconductor substrate to fill up the contact hole
10
. When the contact hole
10
has a high aspect ratio, a cavity
20
is defined as shown in FIG.
1
.
Referring to
FIGS. 1 and 2
, the plug material
2
is totally dryly (anisotropically) etched back, for forming a plug
3
.
Referring to
FIG. 3
, an insulator film
4
is formed on the semiconductor substrate to completely fill up the cavity
20
defined in the plug
3
. The insulator film
4
is preferably formed by an SiN film. While the cavity
20
may not necessarily be filled up with the insulator film
4
, no conductor film can properly fill up the cavity
20
.
Referring to
FIGS. 3 and 4
, the insulator film
4
is totally etched back for filling up the cavity
20
with the insulator film
4
. The thickness of the insulator film
4
and etch-back conditions therefor are so selected as to charge the cavity
20
with the insulator film
4
. The thickness of the insulator film
4
is 4000 to 5000 Å, for example.
Referring to
FIG. 5
, the metal wire
5
is formed on the interlayer isolation film
1
to be in contact with the plug
3
.
FIG. 6
is a plan view of the semiconductor device shown in FIG.
5
.
FIG. 7
is a plan view of the semiconductor device shown in
FIG. 5
causing misregistration in formation of the metal wire
5
. Referring to
FIG. 7
, the cavity
20
is filled up with the insulator film
4
also when the same is not covered with the metal wire
5
, and hence no chemical solution penetrates into the cavity
20
. Thus, the plug
3
is not corroded but forms a reliable contactor.
Referring again to
FIG. 5
, the insulator film
4
is charged in the cavity
20
thereby improving coverage of the metal wire
5
as well as reliability of wiring.
An insulating material such as an SiN film is employed as the material charged in the cavity
20
since the insulating material is hardly corroded by a chemical solution (a resist removing solution, a developer or the like) employed in a step of forming the metal wire
5
and suitably functions as the material for filling up the cavity
20
.
The insulating material can alternatively be prepared from SiO
2
, in place of SiN.
Second Embodiment
While the cavity
20
is completely charged with the insulator film
4
in the first embodiment, the present invention is not restricted to this.
Referring to
FIG. 8
, the surface of a cavity
20
may be covered with an insulator film
4
so that the cavity
20
is not completely filled up with the insulator film
4
. This structure also attains an effect similar to that of the first embodiment. Also when misregistration takes place and the cavity
20
is not covered with a metal wire but a chemical solution penetrates into the cavity
20
, a plug
3
is not corroded since the same is protected with the insulator film
4
. Thus, the plug
3
forms a reliable contactor.
According to the present invention, as hereinabove described, no chemical solution penetrates into a cavity of a plug also when the cavity is not covered with a metal wire, whereby the plug is not corroded. Thus, the plug can effectively form a reliable contactor.
Although the present invention has been described and illustrated in detail, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation, the spirit and scope of the present invention being limited only by the terms of the appended claims.
Claims
- 1. A method of fabricating a semiconductor device comprising steps of:forming an interlayer isolation film on a semiconductor substrate; forming a contact hole in said interlayer isolation film; forming a plug material on said semiconductor substrate to fill up said contact hole; etching back said plug material thereby forming a plug in said contact hole; covering the surface of a cavity defined in said plug with an insulator film; and forming a metal wire on said interlayer isolation film to be in contact with said plug.
- 2. The method of fabricating a semiconductor device according to claim 1, wherein said step of covering the surface of said cavity defined in said plug with said insulator film includes a step of completely filling up said cavity formed in said plug with said insulator film.
- 3. The method of fabricating a semiconductor device according to claim 1, wherein said step of covering the surface of said cavity defined in said plug with said insulator film includes a step of covering the surface of said cavity without completely filling up said cavity formed in said plug with said insulator film.
- 4. The method of fabricating a semiconductor device according to claim 1, wherein said insulator film includes an SiN film.
- 5. The method of fabricating a semiconductor device according to claim 1, applied to a method of fabricating a dynamic random access memory.
- 6. The method of fabricating a semiconductor device according to claim 1, wherein the step of covering the cavity defined in said plug with an insulator film comprises forming the insulator film to cover only a portion where said plug is positioned.
Priority Claims (1)
Number |
Date |
Country |
Kind |
2001-204202 |
Jul 2001 |
JP |
|
US Referenced Citations (11)
Foreign Referenced Citations (2)
Number |
Date |
Country |
6-310605 |
Nov 1994 |
JP |
95-30312 |
Nov 1995 |
KR |