Active solid-state devices (e.g. – transistors – solid-state diode – Combined with electrical contact or lead – Of specified material other than unalloyed aluminum
Reexamination Certificate
2002-01-07
2004-08-03
Cao, Phat X. (Department: 2814)
Active solid-state devices (e.g., transistors, solid-state diode
Combined with electrical contact or lead
Of specified material other than unalloyed aluminum
C257S762000
Reexamination Certificate
active
06770977
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a semiconductor device and a method for fabricating the same, and more particularly it relates to a semiconductor device including an electrode or an interconnect made from a conducting film formed, with a barrier layer disposed therebetween, on an insulating or conducting film provided on a semiconductor substrate and a method for fabricating the same.
Recently, semiconductor integrated circuits having a multi-layer interconnect structure principally made from copper films have been practically used.
A conventional method for fabricating a semiconductor device having a multi-layer interconnect structure principally made from copper films will be described with reference to
FIGS. 9A
,
9
B,
10
A and
10
B.
First, as shown in
FIG. 9A
, an insulating film
11
having an interconnect groove is formed on a semiconductor substrate
10
of silicon, and then, a first tantalum nitride film
12
serving as a barrier layer is deposited on the bottom and the walls of the interconnect groove of the insulating film
11
. Next, after forming a first copper seed layer
13
on the first tantalum nitride film
12
, the first copper seed layer
13
is grown through electroplating so as to form a first copper plating layer
14
. Thus, a lower interconnect composed of the first copper seed layer
13
and the first copper plating layer
14
is formed.
Next, after successively depositing a silicon nitride film
15
serving as an adhesion layer and a first interlayer insulating film
16
on the lower interconnect and the insulating film
11
, a via hole
17
is formed in the first interlayer insulating film
16
and the silicon nitride film
15
. Then, after forming a second interlayer insulating film
18
and a silicon oxide nitrided film
19
serving as an antireflection film on the first interlayer insulating film
16
, the second interlayer insulating film
18
is etched by using the silicon oxide nitrided film
19
as a mask, so as to form an interconnect groove
20
.
Then, as shown in
FIG. 9B
, a second tantalum nitride film
21
serving as a barrier layer is deposited on the bottoms and the walls of the via hole
17
and the interconnect groove
20
by reactive sputtering, and thereafter, a second copper seed layer
22
is formed on the second tantalum nitride film
21
by sputtering.
Subsequently, as shown in
FIG. 10A
, the second copper seed layer
22
is grown through the electroplating so as to form a second copper plating layer
23
. Thereafter, portions of the second tantalum nitride film
21
, the second copper seed layer
22
and the second copper plating layer
23
present on and above the silicon oxide nitrided film
19
are removed by chemical mechanical polishing (CMP), thereby forming a plug
24
and an upper interconnect
25
composed of the second copper seed layer
22
and the second copper plating layer
23
.
However, since the adhesion between the second tantalum nitride film
21
serving as the barrier layer and the upper interconnect composed of the first copper seed layer
22
and the second copper plating layer
23
is not good, peeling is caused between the second tantalum nitride film
21
and the upper interconnect through subsequently conducted annealing, such as annealing for growing a crystal grain of copper. As a result, a void
26
is disadvantageously formed between the plug
24
and the lower interconnect as shown in FIG.
10
B.
When the void
26
is formed between the plug
24
and the lower interconnect, the contact resistance between the plug
24
and the lower interconnect is largely increased.
SUMMARY OF THE INVENTION
In consideration of the aforementioned conventional problem, an object of the invention is improving the adhesion between a barrier layer and a conducting film formed on the barrier layer.
In order to achieve the object, the first semiconductor device of this invention comprises: a barrier layer formed on an insulating or conducting film provided on a semiconductor substrate; and an electrode or an interconnect made from a conducting film formed on said barrier layer, wherein an interatomic distance on an upper plane of said barrier layer and an interatomic distance on a lower plane of said conducting film are nearly equal to each other.
In the first semiconductor device, it is preferable that the barrier layer has a tetragonal crystal structure and the upper plane of the barrier layer is oriented to the (001) plane, and the conducting film has a face-centered cubic crystal structure and the lower plane of the conducting film is oriented to the (111) plane.
In the second semiconductor device of this invention comprises a barrier layer formed on an insulating or conducting film provided on a semiconductor substrate; and an electrode or an interconnect made from a conducting film formed on the barrier layer, and the barrier layer includes a tantalum film having a &bgr;-crystal structure.
In the second semiconductor device of this invention, since the conducting film is formed on the barrier layer made from the tantalum film having the &bgr;-crystal structure, the crystal included in the conducting film is preferentially oriented to a close-packed plane. As a result, the adhesion between the barrier layer and the conducting film can be improved.
In the second semiconductor device, it is preferred that the barrier layer is made from a multi-layer film composed of a lower first barrier layer and an upper second barrier layer, and that the first barrier layer is made from a nitride film and the second barrier layer is made from a tantalum film having a &bgr;-crystal structure.
In this manner, since the insulating or conducting film can be prevented from being in direct contact with the tantalum film having the &bgr;-structure, a harmful compound can be prevented from being generated through a reaction between the insulating or conducting film and the tantalum film having the &bgr;-structure during subsequent annealing.
In the second semiconductor device, in the case where the barrier layer is made from the multi-layer film composed of the lower first barrier layer and the upper second barrier layer, it is preferred that the first barrier layer is made from a tantalum nitride film and that the conducting film is a copper film.
In this manner, the copper atoms included in the copper film can be prevented from diffusing into the insulating film through the barrier layer.
In this case, the copper film is preferably oriented to the (111) plane.
Thus, the adhesion between the copper film and the tantalum film having the &bgr;-structure serving as the barrier layer can be definitely improved.
Also in this case, a value of (a number of nitrogen atoms)/(a number of tantalum atoms) of the tantalum nitride film is preferably 0.4 or less.
Thus, the tantalum film having the &bgr;-structure can be stably deposited on the lower tantalum nitride film.
In the second semiconductor device, in the case where the barrier layer is made from the multi-layer film composed of the lower first barrier layer and the upper second barrier layer and the first barrier layer is made from a nitride film, the insulating or conducting film is preferably an insulating film including a fluorine component.
In this manner, an insulating film having a low dielectric constant can be provided below the electrode or the interconnect made from the conducting film, and hence, the capacitance of the electrode or the interconnect can be lowered. Furthermore, since the first barrier layer is made from a nitride film, tantalum fluoride can be prevented from being generated through a reaction between fluorine included in the insulating film and the tantalum film having the &bgr;-structure during subsequent annealing.
In the second semiconductor device, it is preferred that the insulating or conducting film is an insulating film, that the barrier layer is formed on a bottom and walls of a recess formed in the insulating film, and that the conducting film is a plug or a buried interconnect filled in the recess on the barrier layer.
In
Harada Takeshi
Ikeda Atsushi
Kishida Takenobu
Sugihara Kohei
Tada Shinya
Cao Phat X.
Matsushita Electric - Industrial Co., Ltd.
McDermott Will & Emery LLP
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