Semiconductor device manufacturing: process – Coating with electrically or thermally conductive material – To form ohmic contact to semiconductive material
Reexamination Certificate
2000-03-13
2002-10-15
Chaudhuri, Olik (Department: 2813)
Semiconductor device manufacturing: process
Coating with electrically or thermally conductive material
To form ohmic contact to semiconductive material
C438S624000, C438S643000, C438S644000, C438S687000, C438S688000
Reexamination Certificate
active
06465342
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a semiconductor device and its manufacturing method and more particularly to a semiconductor device and its manufacturing method wherein the deformation of a groove for interconnection by the compressive stress of a barrier metal layer used for an interconnection in a groove (hereinafter called grooved interconnection) having a single damascene structure or a dual damascene structure is prevented.
2. Description of Related Art
The reduction of the resistance of an interconnection and the reduction of the dielectric constant of an interlayer insulating film are desired to meet requests for the miniaturization and speedup of an LSI device. To meet the desire, a copper interconnection lower in electrical resistance, compared with conventional type aluminum alloy interconnection and various organic insulating films lower in a dielectric constant, compared with a conventional type silicon oxide (SiO2) film are examined for actual use.
For technology for forming a copper interconnection, as the dry etching of copper is generally not easy, a method by a so-called grooved interconnection is considered promising. For technology for forming the grooved interconnection, 1) a method of forming an insulating film between interconnection on an interlayer insulating film after embedding interconnection material in a contact hole formed through the interlayer insulating film and embedding interconnection material in a groove after forming the groove on the insulating film (a so-called single damascene method) and 2) a method of simultaneously embedding interconnection material in both a contact hole and a groove after forming both the contact hole and the groove through/on an interlayer insulating film (a so-called dual damascene method) are proposed.
For a method of embedding copper as an interconnection material in a groove and a contact hole, electroplating relatively satisfactory in embeddability and the quality of a film which is a low-temperature process under approximately room temperature is promising. Particularly, it is advantageous in case organic insulating material low in heat resistance is used for an insulating film that electroplating is a low-temperature process.
In the meantime, copper as an interconnection material has a character diffused inside an insulating film. Therefore, to form a copper grooved interconnection, a barrier metal layer is required to be formed between copper and the insulating film. For a barrier metal, tantalum, titanium nitride and tungsten nitride are promising in addition to tantalum nitride used heretofore.
FIG. 13
shows an example that copper grooved interconnection is formed using organic insulating material. As shown in
FIG. 13
, an organic insulating material film
112
is formed on a silicon oxide film
111
and a groove
113
is formed on the organic insulating material film
112
. Grooved interconnection
115
made of copper is formed inside the groove
113
via a barrier metal layer
114
made of tantalum nitride. When the groove
113
is formed by etching, the silicon oxide film
111
functions as an etching stopper. Therefore, the groove
113
is formed in only the organic insulating material film
112
on the silicon oxide film
111
and the bottom of the groove
113
is on the silicon oxide film
111
.
However, as for the grooved interconnection, in case tantalum nitride is used for barrier metal, a problem that the organic insulating material film is deformed by the compressive stress of the tantalum nitride is found. It proves that the deformation is often caused particularly in isolated grooved interconnection or grooved interconnection in close formation (for example, grooved interconnection at the end of a line and space). The reason is that though mechanical strength is weak because organic insulating material is generally small in an elastic modulus and is also low in an elastic limit, barrier metal such as tantalum nitride generally has very high compressive stress.
That is, as shown in
FIG. 14A
, it is considered that the groove
113
is easily deformed inside because the compressive stress of the barrier metal layer
114
particularly made of tantalum nitride widely deposited in an area having no grooved interconnection concentrates at the corner
113
C of the outside groove
113
. It is also considered that the deformation of the groove
113
is promoted because adhesion between the organic insulating material film
112
and the silicon oxide film
111
under the organic insulating material film is not sufficient and sliding occurs between the organic insulating material film
112
and the silicon oxide film
111
by stress concentrating at an interface between the organic insulating material film
112
and the silicon oxide film
111
.
As shown in
FIG. 14B
, as a copper seed layer is not fully deposited in the formation of a film by later sputtering in the groove
113
deformed as described above, failure in embedding copper occurs in electroplating for forming the grooved interconnection
115
. That is, a void B is made in the grooved interconnection
115
.
SUMMARY OF THE INVENTION
The present invention is made to solve the problems and the object is to provide a semiconductor device and its manufacturing method respectively free of the problems.
A semiconductor device according to the invention is based upon a semiconductor device having a groove formed through an insulating film made of organic material on a substrate, a barrier metal layer formed on at least the inner wall of the groove and a grooved interconnection embedded inside the groove via the barrier metal layer and is characterized in that a concave portion is formed through an insulating film around the grooved interconnection. The concave portion is continuously or intermittently formed along the groove within a predetermined interval from the groove. Or the groove is arranged at the end of a group of grooves composed of plural grooves respectively arranged at a predetermined interval and the concave portion is continuously or intermittently formed along the groove within a predetermined interval outside the group of grooves from the groove arranged at the end of the group of grooves.
In the semiconductor device, a barrier metal layer is formed on the inner wall of the groove. Normally, it is difficult to selectively form a barrier metal layer only inside a groove formed through an insulating film because of a characteristic in forming a film and the barrier metal layer is formed not only inside the groove but also on the insulating film. Afterward, in a process for forming a grooved interconnection, a surplus barrier metal layer on the insulating film is removed; however, when a concave portion is formed through the insulating film, the barrier metal layer may be left inside the concave portion. In the invention, in such a semiconductor device, as a concave portion is formed through an insulating film around the grooved interconnection, a barrier metal layer is formed not only inside a groove in which the grooved interconnection is formed but also on the surface of the insulating film and inside the concave portion when the barrier metal layer is formed. Therefore, as compressive stress of the barrier metal layer is relaxed by the concave portion and the large compressive stress of the barrier metal layer is not applied to the groove in which the grooved interconnection is formed, the deformation of the groove is inhibited.
Also, in case the barrier metal layer formed on the inner wall of the groove is also formed on the surface of the insulating film, it is inhibited that the large compressive stress of the barrier metal layer concentrates at the groove because the concave portion is continuously or intermittently formed along the groove within a predetermined interval from the groove. For example, if an interval between the concave portion and the groove is approximately within 20 times of the width of the groove, the interval is enough to inhibit the concentration o
Komai Naoki
Taguchi Mitsuru
Chaudhuri Olik
Kananen, Esq. Ronald P.
Kielin Erik
Rader & Fishman & Grauer, PLLC
Sony Corporation
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