Semiconductor device manufacturing: process – Chemical etching – Combined with the removal of material by nonchemical means
Reexamination Certificate
2001-11-07
2003-11-11
Powell, William A. (Department: 1765)
Semiconductor device manufacturing: process
Chemical etching
Combined with the removal of material by nonchemical means
C216S089000, C438S693000, C438S745000
Reexamination Certificate
active
06645863
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of manufacturing a semiconductor device and a structure of a semiconductor device, in particular, to a method of manufacturing a semiconductor device comprising the step of filling in a metal wire within a contact hole according to a CMP (chemical mechanical polishing) method.
2. Description of the Background Art
FIGS. 19 and 20
are cross section views showing a conventional method for manufacturing a semiconductor device in order of process steps. In reference to
FIG. 19
, first, a semiconductor element such as an MOSFET is formed in a silicon substrate
1
according to a well-known method and, after that, a silicon oxide film
2
as an interlayer insulating film is formed on the silicon substrate
1
. Next, a contact hole
3
which functions as a hole for electrical connection between a wire and a substrate and a recess
4
which functions as an alignment mark are formed in the silicon oxide film
2
according to anisotropic dry etching method. Through the creation of the contact hole
3
, a part of the source and drain regions of the MOSFET is exposed while through the creation of the recess
4
, a part of the top surface of the silicon substrate
1
is exposed. The width of the recess
4
is significantly broader than the width of the contact hole
3
.
Next, a titanium nitride film
5
as a barrier metal is formed on the entire surface according to a spattering method, or the like. Next, a tungsten film
106
as a conductive plug with the film thickness of approximately 400 nm is formed on the entire surface so as to fill in the contact hole
3
according to a CVD method, or the like. Concretely, the temperature is set at approximately 470° C. for the reaction and, first, 25 sccm of WF
6
, 10 sccm of SiH
4
and 800 sccm of H
2
are used as a reactive gas in the atmosphere of 30 Torr of Ar, N
2
so as to layer a seed layer with a film thickness of approximately 100 nm. After that, 75 sccm of WF
6
and 500 sccm of H
2
are used as a reactive gas in the atmosphere of 80 Torr of Ar, N
2
so as to layer a film with a thickness of approximately 300 nm.
In reference to
FIG. 20
, next, the tungsten film
106
and the titanium nitride film
5
are removed through polishing until the top surface of the silicon oxide film
2
is exposed by means of a CMP method. At this time, the contact hole
3
is completely filled in with the tungsten film
106
while the recess
4
having a broad width is not completely filled in with the tungsten film
106
and, therefore, an indentation
7
is created within the recess
4
as shown in FIG.
20
. After that, as the final process of the CMP step, the wafer is cleaned.
In the above described conventional method of manufacturing a semiconductor device, however, the following problem arises.
FIG. 21
is a cross section view showing a partially enlarged view of the structure shown in FIG.
20
. Concretely, the titanium nitride film
5
and the tungsten film
106
formed within the recess
4
are shown partially enlarged. The tungsten film
106
has grains
106
a
in a pillar form with a diameter of approximately 70 nm.
Though a portion of the abrasive material accumulates within the indentation
7
through the CMP process, most of it can be removed through cleaning after polishing. However, as shown in
FIG. 21
, since the diameter of the grains
106
a
is comparatively large, the unevenness of the surface of the tungsten film
6
is comparatively large. Therefore, a portion of the abrasive material
50
which has accumulated in gaps between the grains
106
a
cannot be adequately removed through cleaning and becomes attached to the grains
106
a
as foreign matter. As a result, according to a conventional method of manufacturing a semiconductor device, a problem arises that the abrasive material
50
which has attached to the grains
106
a
again becomes attached to the surface of the wafer in the subsequent step so as to cause a wire pattern defect or a short circuit between the wires.
SUMMARY OF THE INVENTION
According to the first aspect of the present invention, a method of manufacturing a semiconductor device comprises the steps of: (a) preparing a substrate; (b) forming a first film on the substrate; (c) forming a recess by partially hollowing a top surface of the first film in the direction toward the substrate; (d) forming a second film on a structure gained in step (c) with a film thickness such that the recess is not completely filled in; and (e) removing through polishing the second film in a part which is located above the top surface of the first film, wherein a fine grain layer, which has grains of which the diameter is small to the degree that the abrasive material used for polishing in step (e) does not easily become caught in the gaps between the grains, is formed on, at least, a top surface of the second film.
In addition, according to the second aspect of the present invention, a method of manufacturing a semiconductor device is a method of manufacturing a semiconductor device according to the first aspect, wherein the second film where the diameter of the grains in the fine grain layer is approximately 10 nm to 20 nm is formed in step (d).
In addition, according to the third aspect of the present invention, a method of manufacturing a semiconductor device is a method of manufacturing a semiconductor device according to the first or the second aspect, wherein the second film comprising the fine grain layer throughout all the film thickness is formed in step (d).
In addition, according to the fourth aspect of the present invention, a method of manufacturing a semiconductor device is a method of manufacturing a semiconductor device according to the first or the second aspect, wherein the second film having the fine grain layer in only the top surface is formed in step (d).
In addition, according to the fifth aspect of the present invention, a method of manufacturing a semiconductor device comprises the steps of: (a) preparing a substrate; (b) forming a first film on the substrate; (c) forming a first recess by partially hollowing a top surface of the first film in the direction toward the substrate; (d) forming a second film on a structure obtained in step (c) with a film thickness such that the recess is not completely filled in; (e) removing a top surface of the second film by means of isotropic etching; and (f) after step (e), removing through polishing a part of the second film which is located above the top surface of the first film.
In addition, according to the sixth aspect of the present invention, a method of manufacturing a semiconductor device comprises the steps of: (a) preparing a substrate; (b) forming a first film on the substrate; (c) forming a recess by partially hollowing a top surface of the first film in the direction toward the substrate; (d) forming a second film on a structure obtained in step (c) with a film thickness such that the recess is not completely filled in; (e) forming a third film in a thin film form on the second film; (f) removing through polishing a parts of the second and third films which are located above the top surface of the first film; and (g) after step (f), removing the third film which remains in the recess.
In addition, according to the seventh aspect of the present invention, a method of manufacturing a semiconductor device comprises the steps of: (a) preparing a substrate; (b) forming a first film on the substrate; (c) forming a first recess by partially hollowing a top surface of the first film in the direction toward the substrate; (d) forming a second film on a structure obtained in step (c) with a film thickness such that the first recess is not completely filled in; (e) forming a third film with a film thickness such that the level of a top surface thereof agrees with, or is higher than, the level of the top surface of the first film in a second recess which is defined by a top surface of a part of the second film which is formed in the first recess; (f) removing through polishi
Izumitani Junko
Kamoshima Takao
Takewaka Hiroki
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