Semiconductor device manufacturing: process – Making field effect device having pair of active regions... – Having insulated gate
Reexamination Certificate
1998-11-06
2001-02-27
Niebling, John F. (Department: 2812)
Semiconductor device manufacturing: process
Making field effect device having pair of active regions...
Having insulated gate
C438S279000, C438S301000, C438S392000
Reexamination Certificate
active
06194257
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a semiconductor device, and more particularly, to a fabrication method of a gate electrode having a dual gate insulating film.
2. Discussion of the Related Art
A conventional fabrication method of a gate electrode having a dual gate insulating film will be described with reference to the accompanying drawings.
FIGS. 1A-1E
are cross-sectional diagrams sequentially illustrating a conventional fabrication method of the gate electrode having the dual gate insulating film.
As shown in
FIG. 1A
, a first insulating film (gate insulating film)
2
is formed on a semiconductor substrate
1
having a first portion
1
a
and a second portion
1
b
, and a photoresist film
3
is formed thereon. The first insulating film
2
is a silicon oxide film and is usually formed by a thermal oxidation process. A thickness of gate insulating films to be formed on the first and the second portions
1
a
,
1
b
may be different from each other.
As shown in
FIG. 1B
, the photoresist film
3
is etched and patterned to expose the first insulating film
2
corresponding to the second portion
1
b
of the substrate
1
. Therefore, a photoresist film
3
a
is formed.
Next, as shown in
FIG. 1C
, in order to expose the second portion
1
b
of the semiconductor substrate
1
, the first insulating film
2
is etched and patterned using the photoresist pattern
3
a
as a mask. Therefore, a first insulating film pattern
2
a
is formed, and the photoresist pattern
3
a
is then removed by a wet-dip process, wherein the semiconductor substrate
1
including the first insulating film pattern
2
a
and the photoresist pattern
3
a
is dipped into an etching solution and then taken out.
As shown in
FIG. 1D
, a second insulating film
4
(gate insulating film) is formed on the semiconductor substrate
1
having the first insulating film pattern
2
a
, and a conductive film
5
is formed on the second insulating film
4
. The second insulating film
4
is a silicon oxide film and is usually formed by a thermal oxidation process, and the conductive film
5
is a polysilicon film and is usually formed by a chemical vapor deposition (CVD).
As shown in
FIG. 1E
, a gate electrode
6
is respectively formed on the first and the second portions
1
a
,
1
b
of the semiconductor substrate
1
by patterning the conductive film
5
. A thickness of the gate insulating film of the first portion
1
a
is thicker than that of the second portion
1
b.
According to the conventional method, the gate insulating film is often contaminated by infiltrating through a diffusion for metallic and carbonaceous elements of the photoresist film when the gate insulating film is etched and patterned using the photoresist film as a mask, and is easily damaged because it is difficult to control etched volume of the photoresist film. Therefore, the gate insulating film may not have uniform thickness, reducing reliability of the semiconductor device.
SUMMARY OF THE INVENTION
Accordingly, the present invention is directed to a fabrication method of gate electrode having dual gate insulating film that substantially obviates one or more of the problems due to the limitations and disadvantages of the related art.
An object of the present invention is to provide a gate electrode having a dual gate insulating film of high reliability on a semiconductor substrate having a stepped surface.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, in accordance with a first aspect of the present invention there is provided a method of fabricating a gate electrode having dual gate insulating film including the steps of sequentially providing a substrate having a first portion and a second portion, forming a first insulating film on the first portion of the substrate, a first conductive film on the first insulating film and a second insulating film on the first conductive film, forming a third insulating film on the second portion of the substrate, forming a second conductive film on the second and the third insulating films, and patterning the first and the second conductive film to form a gate electrode.
In another aspect of the present invention there is provided a method of forming a gate electrode having dual gate insulating film including the steps of providing a substrate having a first portion and a second portion, forming a first insulating film on the substrate and a second insulating film on the first insulating film, removing the second insulating film corresponding to the first portion to expose the first insulating film, forming a third insulating film by oxidizing the second portion of the substrate, removing the first, second, and third insulating films to form a step in the substrate between the first portion and the second portion, forming a fourth insulating film on the first portion of the substrate, a first conductive film on the fourth insulating film and a fifth insulating film on the first conductive film, forming a sixth insulating film on the second portion of the substrate, forming a second conductive film on the second and the third insulating films, and patterning the first and the second conductive film to form the gate electrode.
In another aspect of the present invention there is provided a method of forming a gate electrode having dual gate insulating film including the steps of providing a substrate having a first portion and a second portion, forming a step in the substrate between the first portion and the second portion, forming a first insulating film on the first portion of the substrate, a first conductive film on the first insulating film and a second insulating film on the first conductive film, forming a third insulating film on the second portion of the substrate, forming a second conductive film on the second and the third insulating films, and patterning the first and second conductive films to form the gate electrode.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.
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patent: 5595922 (1997-01-01), Tigelaar et al.
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patent: 5841174 (1998-11-01), Arai
patent: 5866445 (1999-02-01), Baumann
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Wolf, Silicon Processing for the VLSI Era, vol. 2, pp. 65, 1990.
Hack Jonathan
LG Semicon Co. Ltd.
Morgan & Lewis & Bockius, LLP
Niebling John F.
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