Semiconductor device manufacturing: process – Formation of electrically isolated lateral semiconductive... – Grooved and refilled with deposited dielectric material
Reexamination Certificate
1998-09-21
2001-02-06
Niebling, John F. (Department: 2812)
Semiconductor device manufacturing: process
Formation of electrically isolated lateral semiconductive...
Grooved and refilled with deposited dielectric material
C438S439000, C438S444000
Reexamination Certificate
active
06184106
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of forming an isolation region involved in a semiconductor device, and more particularly to a method of fabricating a semiconductor device having an isolation region of trench type.
2. Description of the Related Art
As the integration of semiconductor devices increases, the separation area between the devices has been made smaller every generation. A conventional local oxidation of silicon (LOCOS) process for submicron technologies is limited by oxide encroachment, as well as by nonplanar surface topographies and the field-thinning effect. A device separation area of trench type has also been used.
The conventional method of forming a device isolation region of trench type will be explained with reference to
FIGS. 1A
,
1
B and
2
.
One of the conventional methods will now be described with
FIGS. 1A and 1B
.
First, as shown in
FIG. 1A
, a silicon oxide film
11
and a silicon nitride film
12
are formed, in order, on the semiconductor substrate
10
. The silicon oxide film
11
and the silicon nitride film
12
are patterned so as to form an opening having a predetermined size. The etching process is accomplished by using the patterned silicon oxide film
11
and silicon nitride film
12
as a mask so that the semiconductor substrate
10
forming a trench groove, only directly under the opening region of the silicon oxide film
11
and the silicon nitride film
12
, is removed. As a result of these steps, a trench groove having predetermined size is formed in the semiconductor substrate
10
. The trench groove surface is etched to remove defects, and a silicon oxide film
13
is formed so as to cover the entire surface of the inner walls of the trench groove. The silicon oxide film
13
is provided as a protection film to remove the defect of surface and to obtain a fine deposition of the device separation film.
As shown in
FIG. 1B
, sequentially, an oxide film
14
a
and
14
b
are deposited on the silicon oxide film
13
covering the inner wall surface of the trench groove so that the trench groove is completely filled with the oxide film. The oxide film
14
a
and
14
b
are etched back on the entire surface so as to obtain a device isolation region of trench type.
However, a device separation film having a fixed thickness can be obtained in the narrow trench region by this method, but the surface of the semiconductor substrate in the wide trench region is exposed.
Another conventional method illustrated in
FIG. 2
is adapted to solve the above mentioned problem that the surface of the semiconductor substrate is exposed due to entire surface etching. Another conventional method will be now described in conjunction with FIG.
2
.
First, a silicon oxide film
21
and a silicon nitride film
22
are formed, in order, on the semiconductor substrate
20
. The silicon oxide film
21
and the silicon nitride film
22
are patterned so as to form an opening having a predetermined size. The etching process is accomplished by using the patterned silicon oxide film
11
and the silicon nitride film
22
as a mask so that the semiconductor substrate
20
forming a trench groove is removed only directly under the opening region of the silicon oxide film
21
and the silicon nitride film
22
. As a result of these steps, a trench groove having predetermined size is formed in the semiconductor substrate
20
. The trench groove surface is etched to remove defects, and a silicon oxide film
23
is formed so as to cover the entire surface of the inner walls of the trench groove. The silicon oxide film
23
is provided as a protection oxide film so as to obtain a fine deposition of the device separation film.
Sequentially, an oxide film
24
a
and
24
b
are deposited on the silicon oxide film
23
covering the inner wall surface of the trench groove so that the trench groove is completely filled with the oxide film. Further, the oxide film
24
a
and
24
b
, except within the trench groove, are unnecessary for the device. Thus, an etch back process is carried out by chemical mechanical polishing (CMP) for the removal of the deposited oxide film, except within the trench groove. By such etch back process, the oxide film is removed so as to remain the oxide film
24
a
and
24
b
within the trench groove only. Therefore, a device isolation region of trench type can be obtained.
However, this method also has the problem of dishing in a relatively wide trench. The dishing may decrease the reliability of the semiconductor device due to the thickness decrease of the device isolation film.
SUMMARY OF THE INVENTION
Therefore, an object of the present invention is to solve the above-mention problems encountered in the prior arts and to provide a method of forming a device isolation film capable of avoiding an occurrence of exposing and dishing in a wide trench region.
In accordance with one aspect, the present invention provides a method of manufacturing a semiconductor device comprising the steps of forming a device isolation film on a main surface of a semiconductor substrate: forming a first oxidation prevention film on the main surface of a semiconductor substrate, sequentially etching respective predetermined portions of said first oxidation prevention film to form a device isolation region; etching said semiconductor substrate to form a trench groove by using the patterned said first oxidation prevention film as a mask, and etching the trench groove surface to remove a defects; forming a second oxidation prevention film on the entire surface of the semiconductor substrate, and pattering said second oxidation prevention film; forming a first device separation film on the entire exposed surface of said semiconductor substrate; etching said second oxidation prevention film; depositing an oxide film to form a second device isolation region on the trench groove surface; and etching the oxide film except within the trench groove.
In accordance with another aspect, the present invention provides a method for manufacturing a semiconductor device comprising the steps of forming a device isolation film on the main surface of a semiconductor substrate: forming a first oxidation prevention film on a main surface of a semiconductor substrate, sequentially etching respective predetermined portions of said first oxidation prevention film to form a device isolation region; etching said semiconductor substrate to form a trench groove by using the patterned said first oxidation prevention film as a mask, and etching the trench groove surface to remove defects; forming a second oxidation prevention film on the entire surface of the semiconductor substrate, and pattering said second oxidation prevention film; forming a first device isolation film by the thermal oxidation process on the entire exposed surface of said semiconductor substrate; etching said second oxidation prevention film; depositing a CVD oxide film to form a second device isolation region on the trench groove; and forming a second device separation film by the etching process.
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Hyundai Electronics Industries Co,. Ltd.
Jacobson Price Holman & Stern PLLC
Jones Josetta
Niebling John F.
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