Active solid-state devices (e.g. – transistors – solid-state diode – Integrated circuit structure with electrically isolated... – Passive components in ics
Reexamination Certificate
2002-07-19
2004-12-28
Pert, Evan (Department: 2829)
Active solid-state devices (e.g., transistors, solid-state diode
Integrated circuit structure with electrically isolated...
Passive components in ics
Reexamination Certificate
active
06835998
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a semiconductor device and a method of manufacturing the same, and more particularly, to a fuse area structure in a semiconductor device and a method of forming the same.
2. Description of the Related Art
In general, a semiconductor device is realized by stacking various material layer patterns, and the uppermost layer thereof is covered with a passivation film. The passivation film is generally formed of a hard material such as silicon nitride. The passivation film absorbs mechanical, electrical, and chemical shock, thus protecting the semiconductor device.
In general, semiconductor devices such as semiconductor memory devices are subjected to a repair process to replace circuits that do not operate due to defects. The defective circuits are generally either replaced by redundant circuits or a trimming process is used to change the characteristics of some circuits such that they are suitable for a particular application. The repair process or the trimming process is performed by cutting part of a predetermined interconnection by irradiating with a laser. The interconnection cut by the irradiating laser is referred to as a fuseline. The cut part and area surrounding it are referred to as a fuse area.
FIG. 1
is a sectional view showing part of a memory cell and a fuse area of a conventional semiconductor device, in particular, a DRAM device employing a multi-layer metal interconnection structure.
The left side of
FIG. 1
shows a cell array area, which includes a memory cell constituted of a transistor
14
,
16
, and
18
and a capacitor
30
,
32
, and
34
, multi-layer metal interconnections
38
and
42
, interlayer dielectric films
20
,
26
,
36
, and
40
, and a passivation film
44
. Also, the right side of
FIG. 1
shows the fuse area, which includes a fuse line, that is, a bitline
24
, connected to the drain region
16
of the transistor by a bitline contact plug
22
and a fuse opening
50
obtained by etching interlayer dielectric films
36
and
40
and the passivation film
44
on the fuse line
24
by a predetermined width. The laser is irradiated through the fuse opening
50
to cut the fuse line
24
under the fuse opening
50
. A field oxide
12
is formed on a substrate
10
.
Here, each of the interlayer dielectric films
20
,
26
,
36
, and
40
is described as a single-layer film. However, each can be a multiple-layer film obtained by stacking multiple layers. Also, a lower electrode contact plug
28
for electrically connecting a source region
18
of the transistor to the lower electrode
30
of the capacitor is located on a different plane to the plane on which the bitline
24
exists. That is, the lower electrode contact plug
28
does not contact the bitline
24
. Here, it is described that the bitline
24
is used as the fuse line. However, the wordline
14
can be used as the fuse line. Another interconnection can be used as the fuse line in semiconductor devices other than memory devices. The above is also applied to the embodiments of the present invention, which will be described below.
The fuse area of the general semiconductor device having the structure as shown in
FIG. 1
exhibits certain problems. The interlayer dielectric films
26
,
36
, and
40
exposed on the sidewall of the fuse opening
50
are formed of silicon oxide, in particular, boron phosphorous silicate glass (BPSG), phosphorous silicate glass (PSG), spin on glass (SOG), tetra ethyl ortho silicate (TEOS), and undoped silicate glass (USG) which have an excellent step coverage, in order to reduce a large step difference between a cell array area and a peripheral circuit area. However, the BPSG, the PSG, the SOG, and the TEOS, which contain a large amount of impurities, for example, greater than or equal to 5 weight % of boron or greater than or equal to 4 weight % of phosphorous, are vulnerable to moisture. The reliability of a semiconductor device in which a fuse area was formed is tested at the temperature of between 100 and 150° C., under the humidity of between 80 and 100%, and under the pressure of between 1.5 and 3 atm. During this test, when moisture seeps into the interfaces between the interlayer dielectric films, which are vulnerable to moisture, as shown in
FIG. 2
, interfaces between metal interconnections
38
and
42
formed of tungsten or aluminum and the interlayer dielectric films
36
and
40
under the metal interconnections
38
and
42
in an adjacent peripheral circuit are peeled from each other as denoted by reference numeral
52
. Accordingly, the electrical resistance of a metal contact increases and the reliability of the semiconductor device is severely deteriorated. It seems that because the energy level of the interface between the layers is lower than the energy level inside the respective layers that the moisture seeps into the interface between the interlayer dielectric films
26
,
36
, and
40
and the passivation film
44
and the interface between the interlayer dielectric films
36
and
40
and the metal interconnections
38
and
42
.
In order to solve this problem as shown in
FIG. 3
, a fuse area in which a protection film
46
is formed of a material such as silicon nitride on the sidewall of the fuse opening
50
is provided in the invention disclosed in U.S. Pat. No. 5,879,966. However, in order to form the protection film
46
, a process of depositing the silicon nitride film on the passivation film
44
and a photolithography process of exposing the interlayer dielectric film
26
on the bottom of the fuse opening
50
must be additionally performed.
The fuse opening
50
shown in
FIGS. 1 and 3
is formed by allowing a predetermined thickness of the interlayer dielectric film
26
to remain on the fuse line
24
by sequentially etching the passivation film
44
and the interlayer dielectric films
40
,
36
, and
26
after forming the passivation film
44
of the uppermost layer. Here, the films to be etched are significantly thick. Accordingly, it takes a long time to etch the films. Also, it is difficult to accurately control the thickness of the interlayer dielectric film
26
left on the fuse line
24
.
SUMMARY OF THE INVENTION
To solve the above problems, it is an object of the present invention to provide a fuse area structure in a semiconductor device capable of preventing moisture from seeping into the sidewall of a fuse opening.
It is another object of the present invention to provide a method of forming a fuse area of a semiconductor device by which it is possible to form a protection film on the sidewall of a fuse opening without additional processes.
It is still another object of the present invention to provide a method of forming a fuse area of a semiconductor device by which it is possible to reduce the time taken for etching the fuse opening without additional processes and to accurately control the thickness of an interlayer dielectric film left on a fuse line.
In accordance with the invention, there is provided a fuse area structure in a semiconductor device. The structure includes a fuse line and a first interlayer dielectric film formed on the fuse line and exposed by a fuse opening. A second interlayer dielectric film is formed on the first interlayer dielectric film, and the fuse opening is formed in the second interlayer dielectric film. A passivation film, which operates as a protection film for preventing moisture from seeping into the sidewall of the fuse opening, is integrally formed on the uppermost layer of the semiconductor device, on the second interlayer dielectric film, and the sidewall of the fuse opening.
The passivation film can be formed of a moisture-proof film, such as a silicon nitride film, a silicon oxide film or a compound film of silicon nitride and silicon oxide films.
In one embodiment, the first interlayer dielectric film is recessed from the surface of the first interlayer dielectric film in a portion exposed by the fuse opening. An interface between the first and second interlayer dielectric fi
Ban Hyo-dong
Kho Sung-hoon
Lee Chi-hoon
Park Young-hoon
Mills & Onello LLP
Pert Evan
LandOfFree
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