Active solid-state devices (e.g. – transistors – solid-state diode – Field effect device – Having insulated electrode
Reexamination Certificate
2001-05-17
2003-08-05
Nguyen, Tuan H. (Department: 2813)
Active solid-state devices (e.g., transistors, solid-state diode
Field effect device
Having insulated electrode
C257S310000, C257S528000
Reexamination Certificate
active
06603163
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to semiconductor devices and methods of manufacturing thereof. In particular, the invention relates to a semiconductor device having a capacitor and a method of manufacturing the semiconductor device.
2. Description of the Background Art
An analog or analog•digital LSI (Large Scale Integration) such as analog/digital converter (A/D converter) and digital/analog converter (D/A converter) conventionally contains a capacitor (capacitive element) as a component of a filter circuit or an integrating circuit.
FIG. 89
is a schematic cross section of a semiconductor device, conventional analog•digital LSI and the like for example, showing a capacitor portion where a capacitor is formed and an interconnection portion where an interconnection is formed.
FIG. 90
is a schematic cross section along line XC—XC in
FIG. 89. A
conventional semiconductor device is described below in conjunction with
FIGS. 89 and 90
.
Referring to
FIGS. 89 and 90
, an insulating film
102
is formed on a semiconductor substrate
101
. A capacitor portion
120
includes one electrode
103
a
formed of a metal film that is deposited on insulating film
102
. The other electrode
103
b
is formed to surround one electrode
103
a
with a space therebetween. An interlayer insulating film
108
is formed on one electrode
103
a
and the other electrode
103
b
. An interlayer insulating film part
108
a
is provided as a capacitor dielectric film between one electrode
103
a
and the other electrode
103
b
. The one electrode
103
a
, interlayer insulating film part
108
a
and the other electrode
103
b
constitute a capacitor.
A contact hole
110
a
formed in interlayer insulating film
108
is located in a region on one electrode
103
a
. A tungsten plug
111
a
fills the inside of contact hole
110
a
. An upper-level interconnection
112
a
is formed on tungsten plug
111
a
. Upper-level interconnection
112
a
is electrically connected to one electrode
103
a
via tungsten plug
111
a.
An interconnection portion
121
includes a first-level interconnection
103
c
formed on insulating film
102
. The first-level interconnection
103
c
is constituted of a layer of the same level as that of one electrode
103
a
and the other electrode
103
b
. Interlayer insulating film
108
is deposited on the first-level interconnection
103
c
. A contact hole
110
b
is formed in interlayer insulating film
108
in a region on the first-level interconnection
103
c
. A tungsten plug
111
b
fills the inside of contact hole
110
b
. An upper-level interconnection
112
b
is formed on tungsten plug
111
b
. The upper-level interconnection
112
b
is electrically connected to the first-level interconnection
103
c
via tungsten plug
111
b.
The conventional semiconductor device as described above has a problem as discussed below. There is an increasing demand for scaling down and enhanced integration of semiconductor devices. The capacitor as shown in
FIGS. 89 and 90
must secure a certain capacitance. In order to reduce the area occupied by the capacitor shown in
FIGS. 89 and 90
while maintain a required capacitance, the thickness in the direction of height of one electrode
103
a
and the other electrode
103
b
can be increased to extend the surface area of sidewalls of one electrode
103
a
and the other electrode
103
b
serving as electrodes, or the distance between one electrode
103
a
and the other electrode
103
b
can be reduced.
However, when the thickness in the height direction of the one and the other electrodes
103
a
and
103
b
is increased, etching for fabricating the one and the other electrodes
103
a
and
103
b
is difficult. Therefore, this is not a realistic approach. On the other hand, when the distance between the one electrode
103
a
and the other electrode
103
b
is decreased, it would be difficult to reduce the distance smaller than the minimum process dimension of photolithography employed in a manufacturing process of the semiconductor device. Reduction of the area occupied by the capacitor is accordingly restricted.
It has been difficult for the conventional semiconductor device to secure a certain capacitance while reduce the area occupied by the capacitor as explained above.
SUMMARY OF THE INVENTION
One object of the present invention is to provide a semiconductor device having a capacitor enabling a certain capacitance to be secured and simultaneously allowing the size to be reduced, and to provide a method of manufacturing such a semiconductor device.
According to one aspect of the invention, a semiconductor device includes a capacitor lower electrode having an upper surface and including a metal film, a dielectric film deposited on the capacitor lower electrode and having its thickness smaller than that of the capacitor lower electrode, and a capacitor upper electrode deposited on the dielectric film, having its width smaller than that of the capacitor lower electrode and including a metal film.
The capacitor lower electrode, the dielectric film and the capacitor upper electrode are stacked in the vertical direction and accordingly a capacitor can be produced in the vertical direction. It is possible to control the thickness of the dielectric film such that the thickness is significantly smaller than the minimum process dimension of photolithography employed in fabrication of the semiconductor device. Then, with a certain capacitance secured, the thickness of the dielectric film can be made smaller than the conventional one to decrease the surface area of the capacitor upper and lower electrodes. As a result, the capacitor can be reduced in size compared with the conventional capacitor.
The width of the capacitor upper electrode is defined smaller than that of the capacitor lower electrode. It is then possible to obtain an increased alignment margin for photolithography by which the capacitor upper electrode is formed. Occurrence of defect can be avoided, such as short-circuit between the sidewall for example of the capacitor lower electrode and the capacitor upper electrode due to misalignment of the capacitor upper and lower electrodes.
As the capacitor upper and lower electrodes include metal films, a capacitor (capacitive element) can be implemented having a higher precision and less voltage-dependency, compared with a semiconductor device employing semiconductor like polysilicon as a capacitor electrode. A capacitor necessary for a high-precision filter circuit or the like can readily be achieved in this way.
For the semiconductor device according to the one aspect, the capacitor upper electrode may have a sidewall, and the semiconductor device may include a sidewall insulating film formed on the upper surface of the capacitor lower electrode and on the sidewall of the capacitor upper electrode.
The sidewall insulating film provided between the sidewall of the capacitor upper electrode and the upper surface of the capacitor lower electrode can surely prevent short-circuit between the capacitor upper electrode and the capacitor lower electrode.
Further, as discussed later regarding a manufacturing process, the capacitor upper electrode and the sidewall insulating film can be utilized as a mask in etching for fabricating the capacitor lower electrode. Accordingly, the capacitor lower electrode located under the capacitor upper electrode and having its width greater than that of the capacitor upper electrode can surely be formed.
For the semiconductor device according to the one aspect, the sidewall insulating film preferably includes a silicon oxynitride film.
The silicon oxynitride film functions as an ARC (Anti Reflection Coat). A separate ARC is thus made unnecessary by forming the silicon oxynitride film constituting the sidewall insulating film from a region on the capacitor upper electrode to another region and forming on this silicon oxynitride film a photoresist film employed in etching for forming an interconnection or the like on that another region. The manufacturing pr
Akazawa Moriaki
Hori Katsunobu
Matsunuma Takeshi
Shiozawa Kenichiro
McDermott & Will & Emery
Mitsubishi Denki & Kabushiki Kaisha
Nguyen Tuan H.
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