Semiconductor device manufacturing: process – Making passive device – Stacked capacitor
Reexamination Certificate
2000-03-31
2002-02-05
Nguyen, Tuan H. (Department: 2813)
Semiconductor device manufacturing: process
Making passive device
Stacked capacitor
C438S003000, C438S240000
Reexamination Certificate
active
06344400
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of manufacturing a capacitor, and more particularly to a method of manufacturing a capacitor comprising a capacitor dielectric film made of an oxide.
2. Description of the Background Art
FIGS. 13
to
17
are sectional views sequentially showing the steps of a method of manufacturing a semiconductor device comprising a capacitor according to the prior art. First of all, an element isolating film
102
is formed on an upper face of a semiconductor substrate
101
. Then, a gate structure having a gate oxide film
104
and a gate electrode
105
provided in that order is selectively formed on the upper face of the semiconductor substrate
101
in an element forming region. Next, ions are implanted by using the gate structure and the element isolating film
102
as masks. Consequently, a source region
103
s
and a drain region
103
d
are formed in the upper face of the semiconductor substrate
101
(FIG.
13
).
Subsequently, an insulating film
106
covering side and upper faces of the gate structure is formed, and a bit line
107
is then formed in contact with the source region
103
s.
Thereafter, an insulating film is deposited over the whole face and is then etched back. Consequently, an interlayer insulating film
109
is formed. Next, a contact hole
110
reaching an upper face of the drain region
103
d from an upper face of the interlayer insulating film
109
is formed and a plug layer
111
to fill in the contact hole
110
is then formed (FIG.
14
).
Next, a barrier metal layer is formed over the whole face. Then, a noble metal film is formed on the barrier metal layer by a sputtering method or a CVD method using an organic noble metal compound for a source. Then, a resist having a predetermined opening pattern is formed on the noble metal film. By using the resist as a mask, thereafter, the noble metal film and the barrier metal layer are subjected to etching in that order by an anisotropic dry etching method in a gas plasma atmosphere. Consequently, a barrier metal layer
112
to come in contact with the plug layer
111
and a storage node
113
are formed (FIG.
15
).
Subsequently, a noble metal film is formed over the whole face by the sputtering method or the CVD method using an organic noble metal compound for a source. Then, the noble metal film is subjected to etching by the anisotropic dry etching method in the gas plasma atmosphere. Consequently, a side wall portion
114
is formed on side faces of the barrier metal layer
112
and the storage node
113
(FIG.
16
). The side wall portion
114
functions as a first electrode of a capacitor together with the storage node
113
.
Next, a capacitor dielectric film
115
made of a high dielectric film or a ferroelectric film is formed over the whole face. Subsequently, a cell plate
116
functioning as a second electrode of the capacitor is formed on the capacitor dielectric film
115
. Then, an insulating film is formed on the cell plate
116
, and is thereafter etched back, thereby forming an interlayer insulating film
117
. Next, an aluminum wiring
118
, an interlayer insulating film
119
, an aluminum wiring
120
and a protective film
121
are formed in that order by a well-known method. Thus, a device is completed (FIG.
17
).
However, such a method of manufacturing a semiconductor device according to the prior art has had the following problems.
First Problem
According to the method of manufacturing a semiconductor device according to the prior art, a noble metal film is processed by the anisotropic dry etching method at the steps shown in
FIGS. 15 and 16
. However, a noble metal generally has a very poor workability. For example, at the step of etching the noble metal film shown in
FIG. 15
, a reaction product generated by the etching is deposited on the side face of the storage node
113
or the like to form a re-deposited film so that the side face of the storage node
113
becomes tapered in some cases. A foreign matter removing method of removing the re-deposited film has also been known. However, a material of the re-deposited film is almost the same as that of the storage node
113
and depositing force for the storage node
113
is comparatively great. Therefore, removing force for removing the re-deposited film should be set great. For this reason, if a size of the storage node
113
is reduced with microfabrication of a semiconductor device, the storage node
113
itself is also removed at the foreign matter removing step. Accordingly, there has been a problem in that it is very difficult to form a fine storage node
113
having a half pitch of 0.25 &mgr;m or less (The half pitch means half of a formation pitch of a structure which is formed repetitively at regular intervals. In
FIG. 15
, for example, the half pitch is equivalent to half of a space between a left end of the storage node
113
on the left side and a left end of the storage node
113
on the right side).
Second Problem
As described with reference to the steps shown in
FIGS. 15 and 16
, the noble metal film can be formed by the sputtering method or the CVD method. In consideration of the goodness of step coverage, however, it is desirable that the noble metal film should be formed by the CVD method. An example of a method of forming a storage node using the step of depositing a noble metal film by the CVD method has been disclosed in Japanese Laid-Open Patent Publication No. Hei 10-289985. In the case where the noble metal film is to be formed by the CVD method, an organic noble metal compound has conventionally been used as a source of the CVD.
However, if the organic noble metal compound is used as the source of the CVD, carbon or an organic molecule which is contained in the source of the CVD remains in the storage node
113
and the side wall potion
114
. There has been a problem in that the remaining carbon or organic molecule causes an oxidation reaction when the capacitor dielectric film
115
is deposited at the next step, thereby generating carbon dioxide and water.
Under the present circumstances, all the high dielectric films or ferroelectric films which are the materials of the capacitor dielectric film
115
are oxides. Accordingly, when the capacitor dielectric film
115
is to be formed, it is essential that the atmosphere should be set to have oxidation properties. Therefore, it is impossible to prevent the carbon dioxide and water from being generated by the carbon or organic molecule remaining in the storage node
113
and the side wall portion
114
. In addition, the noble metal generally has a high catalytic action for an oxidation-reduction reaction. For this reason, the oxidation reaction is caused more easily.
The carbon dioxide and the water which are generated by the oxidation reaction affect a semiconductor device in the following manner. Referring to a bad influence of the carbon dioxide, first of all, the carbon dioxide is an acidic gas and easily reacts to a high dielectric film or a ferroelectric film which is a basic oxide, thereby generating a carbonate. For example, in the case where barium strontium titanate ((Ba, Sr) TiO
3
: BST) is used as the high dielectric film, an acid-base reaction represented by the following reaction formula is easily caused.
(Ba, Sr)TiO
3
+CO
2
→(BaCO
3
+SrCO
3
)+TiO
2
(A reaction factor is omitted.)
As a result, a carbonate of an alkaline earth metal is generated in the high dielectric film or the ferroelectric film. The carbonate causes a decrease in a dielectric constant and a deterioration in a breakdown voltage and reliability.
Referring to a bad influence of the water, when the generated water is decomposed on a surface of the storage node
113
to generate hydrogen, the hydrogen reduces the high dielectric film or the ferroelectric film, resulting in a deterioration in a breakdown voltage. Furthermore, if the carbonate is generated as described above, the water dissolves the carbonate. Therefore, the water has a seriously bad influence such
Mitsubishi Denki & Kabushiki Kaisha
Nguyen Tuan H.
LandOfFree
Method of manufacturing capacitor does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method of manufacturing capacitor, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of manufacturing capacitor will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2980128