Active solid-state devices (e.g. – transistors – solid-state diode – Field effect device – Having insulated electrode
Reexamination Certificate
2000-05-15
2001-12-04
Meier, Stephen D. (Department: 2822)
Active solid-state devices (e.g., transistors, solid-state diode
Field effect device
Having insulated electrode
C257S353000, C257S354000
Reexamination Certificate
active
06326665
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a semiconductor device, and more particularly, to a semiconductor device and a method for fabricating the same that reduces a short channel effect.
2. Background of the Related Art
Generally, in fabricating a semiconductor integrated circuit, various efforts continue at reducing the dimensions of a metal oxide semiconductor field effect transistor (MOSFET) constituting a semiconductor chip integrated circuit that has excellent performance and high packing density. As a result of such efforts, a semiconductor integrated circuit and a method of making the same have been scaled down to a sub-micron size.
In reducing the dimensions of the semiconductor device, the vertical dimension as well as the horizontal dimension should be reduced to balance the characteristics of various devices. In other words for a transistor, if the distance between a source and a drain becomes close, a characteristic of the device is varied, which causes an undesired characteristic such as the short channel effect. To improve such short channel effects caused by high packing density, a lightly doped drain (LDD) structure is adopted in which a low density junction is formed below a gate sidewall.
A related art semiconductor device and a method for fabricating the same will now be described.
FIG. 1
is a diagram showing a sectional view of the related art semiconductor device.
As shown in
FIG. 1
, a gate insulating film
12
is formed on a semiconductor substrate
11
. A gate electrode
13
a
is formed in a predetermined region on the gate insulating film
12
. A sidewall insulating film
16
is formed at both sides of the gate electrode
13
a.
A heavily doped impurity region
17
having an LDD structure is formed in a surface of the semiconductor substrate
11
at both sides of the gate electrode
13
a.
FIGS. 2
a
to
2
d
are diagrams showing sectional views of a method for fabricating the related art semiconductor device. As shown in
FIG. 2
a,
a channel ion is implanted into the entire surface of the semiconductor substrate
1
. A gate insulating film
12
is formed on the semiconductor substrate
11
into which the channel ion is implanted. A polysilicon layer
13
for a gate electrode is formed on the gate insulating film
12
. Subsequently, a photoresist
14
is deposited on the polysilicon layer
13
and then patterned by exposure and developing processes to define a gate region.
As shown in
FIG. 2
b,
the polysilicon layer
13
is selectively removed using the patterned photoresist
14
as a mask to form a gate electrode
13
a.
As shown in
FIG. 2
c,
the photoresist
14
is removed, and an n type lightly doped impurity ion is implanted into the entire surface of the semiconductor substrate
11
using the gate electrode
13
a
as a mask to form a lightly doped impurity region
15
in the surface of the semiconductor substrate
11
. Thus, the lightly doped impurity region
15
is formed at both sides of the gate electrode
13
a.
As shown in
FIG. 2
d,
an insulating film (not shown) is formed on the entire surface of the semiconductor substrate
11
including the gate electrode
13
a.
The insulating film is then etched back to form a sidewall insulating film
16
at both sides of the gate electrode
13
a.
Subsequently, an n type heavily doped impurity ion, which is used for a source and a drain, is implanted into the entire surface of the semiconductor substrate
11
using the sidewall insulating film
16
and the gate electrode
13
a
as masks. A heavily doped impurity region
17
, which is connected with the lightly doped impurity region
15
, is thereby formed in the surface of the semiconductor substrate
11
at both sides of the gate electrode
13
a.
However, the related art semiconductor device and method for fabricating the same have various problems. In the related art semiconductor device and the method for fabricating the same reliability deteriorates because of a short channel effect caused by diffusing impurity ions of the heavily doped impurity region into the channel region.
The above references are incorporated by reference herein where appropriate for appropriate teachings of additional or alternative details, features and/or technical background.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a semiconductor device and a method for fabricating the same that substantially obviate one or more of the problems caused by limitations and disadvantages of the related art.
Another object of the present invention is to provide a semiconductor device and a method for fabricating the same having an insulating film is formed at sides of a heavily doped impurity region.
Another object of the present invention is to provide a semiconductor device and a method for fabricating the same that prevents diffusing of impurity ions of the heavily doped impurity region.
Another object of the present invention is to provide a semiconductor device and a method for fabricating the same that prevents impurity ions of the heavily doped impurity region from diffusing to a channel region.
Another object of the present invention is to provide a semiconductor device and a method for fabricating the same that increases reliability of the device.
To achieve at least these objects and other advantages in a whole or in parts and in accordance with the purpose of the present invention, as embodied and broadly described, a semiconductor device according to the present invention includes a gate insulating film on a prescribed portion of a semiconductor substrate, a gate electrode on the gate insulating film, a lightly doped region in the semiconductor substrate at both sides of the gate electrode, sidewall insulating films formed at both sides of the gate electrode and the gate insulating film, heavily doped impurity regions in the semiconductor substrate extending from a side of the sidewall insulating films opposite the gate electrode, and insulating films positioned at sides of the heavily doped impurity region.
To further achieve the above objects in a whole or in parts, a method for fabricating a semiconductor device is provided according to the present invention that includes the steps of forming insulating films on a semiconductor substrate having prescribed dimensions and separated by a prescribed distance, forming a semiconductor layer on an entire surface of the semiconductor substrate including the insulating films, forming, a gate on the semiconductor layer between pairs of the insulating films, forming a lightly doped impurity region in a surface of the semiconductor layer at both sides of the gate, forming a first sidewall insulating film at both sides of the gate, and forming, a heavily doped impurity regions in the semiconductor layer at both sides of the gate, the heavily doped impurity region being isolated from each other by the insulating film.
To further achieve the objects in a whole or in parts, a method for fabricating a semiconductor device is provided according to the present invention that includes the steps of forming a gate insulating film and a gate electrode on a semiconductor substrate, etching, the semiconductor substrate at both sides of the gate electrode to a predetermined depth from the top surface to form a trench, forming an insulating film on the surface of the semiconductor substrate in the trench, forming a first sidewall insulating film at both sides of the gate electrode, the gate insulating film, and the trench, selectively removing the insulating film using the gate electrode and the first sidewall insulating film as masks, removing the first sidewall insulating film, forming a semiconductor layer on the entire surface of the semiconductor substrate including the insulating film, and forming a heavily doped impurity regions in the semiconductor layer at both sides of the gate electrode, wherein the heavily doped impurity regions are isolated from each other by the insulating film.
Additional advantages, objects, and features of the invention will be s
Park Sung Kye
Shin Eun Jeong
Fleshner & Kim LLP
Hyundai Electronics Industries Co,. Ltd.
Johnson C.
Meier Stephen D.
LandOfFree
Semiconductor device with insulating films does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Semiconductor device with insulating films, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Semiconductor device with insulating films will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2583476