Semiconductor device manufacturing: process – Formation of electrically isolated lateral semiconductive...
Reexamination Certificate
1998-07-23
2001-01-16
Nelms, David (Department: 2818)
Semiconductor device manufacturing: process
Formation of electrically isolated lateral semiconductive...
C438S509000, C438S530000, C438S653000, C505S425000, C505S473000, C505S475000, C505S480000
Reexamination Certificate
active
06174783
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a semiconductor device having a trench structure and its manufacturing method. In particular, the invention relates to a semiconductor device and its manufacturing method which include a structure or a method of covering a trench formed in a semiconductor substrate with an insulating film.
2. Background Art
FIGS. 8 and 9
are schematic sectional views illustrating formation of an insulating film in a conventional semiconductor device manufacturing method. That is,
FIGS. 8 and 9
show the main part in steps of forming a trench for, for instance, device isolation in a semiconductor substrate and covering the trench with an insulating film.
The manufacturing steps will be described below with reference to
FIGS. 8 and 9
. First, as shown in
FIG. 8
, the surface of a semiconductor substrate
1
is formed with a device isolation trench
2
by etching or the like. An insulating film
3
is formed by CVD or the like so as to cover the trench
2
.
FIG. 8
shows the initial stage of the formation of the insulating film
3
. Although the insulating film
3
is normally formed on the surface of the semiconductor substrate
1
excluding the trench
2
, on the side surfaces
5
of the trench
2
it is formed at a relatively small thickness at a low density. In particular, the insulating film
3
is not grown sufficiently on the bottom
6
of the trench
2
.
FIG. 9
shows the final stage of the formation of the insulating film
3
, in which the insulating film
3
grows so as to close the surface opening
4
of the trench
2
. In this state, the insulating film
3
is not sufficiently grown inside the trench
2
, particularly on its bottom
6
; there is a possibility that an insulator portion
7
having a low density or an interstice is formed.
As described above, in the insulating film forming method of the conventional semiconductor device manufacturing method, in the step of covering the trench
2
formed in the semiconductor substrate
1
with the insulating film
3
, the surface opening
4
of the trench
2
is closed by the part of the insulating film
3
that has grown on the surface of the semiconductor substrate
1
. Therefore, the low-density insulator portion
7
may be formed inside the trench
2
.
More specifically, in the trench isolation structure for device isolation of a semiconductor device, when an insulating film is formed by an ordinary CVD method or a like technique in filling in a trench with the insulating film, it is difficult to satisfactorily form the insulating film in the deepest portion of the trench, possibly forming a low-density insulator portion. This may render the device isolation incomplete and hence adversely affect the electrical characteristics.
SUMMARY OF THE INVENTION
The present invention has been made to solve the above problems in the conventional art, and an object of the present invention is therefore to provide a semiconductor device manufacturing method and apparatus which can bury, with superior coverage, an insulating film in a trench that is formed in a semiconductor substrate, as well as a semiconductor device having an insulating film that has been formed by the above manufacturing method and apparatus and is superior in burying performance.
According to one aspect of the present invention, in a manufacturing method of a semiconductor device, a semiconductor substrate, having a trench formed on the front surface thereof, is accommodated in a processing chamber to form an insulating film on the front surface of said semiconductor substrate. A reactive gas for forming an insulating film is introduced into the processing chamber. The semiconductor substrate accommodated in the processing chamber is heated from a back side of the semiconductor substrate. Thereby, an insulating film is formed on the front surface of the semiconductor substrate.
In another aspect of the present invention, in the manufacturing method, the insulating film is formed while a back surface of the semiconductor substrate is kept at a higher temperature than the front surface thereof.
In another aspect of the present invention, in the manufacturing method, the insulating film is formed in a high vacuum state in which a surface reaction on the semiconductor substrate is dominant over a vapor-phase reaction.
In the manufacturing method, the insulating film is formed preferably while a back surface of the semiconductor substrate is heated.
In the manufacturing method, the insulating film is formed preferably while a back surface and the front surface of the semiconductor substrate are heated so that the front surface is kept at a lower temperature than the back surface.
In the manufacturing method, the insulating film is preferably formed while the front surface of the semiconductor substrate is kept at a lower temperature than the back surface thereof by blowing a gas for forming the insulating film against the front surface of the semiconductor substrate.
In the manufacturing method, the insulating film is preferably formed while heat dissipation from the front surface of the semiconductor substrate is accelerated, the front surface of the semiconductor substrate being roughened in advance except for the trench.
According to one aspect of the present invention, a manufacturing apparatus of a semiconductor device comprises a processing chamber for accommodating a semiconductor substrate to form an insulating film on a front surface of said semiconductor substrate. Reactive gas introducing means is provided for introducing a reactive gas for forming the insulating film into the processing chamber. Firstheating means is provided for heating the semiconductor substrate accommodated in the processing chamber from a back side of the semiconductor substrate. Thereby, the insulating film is formed on the front surface of the semiconductor substrate while the semiconductor substrate is heated from the backside thereof.
In another aspect of the present invention, the manufacturing apparatus further comprises second heating means for heating the semiconductor substrate accommodated in the processing chamber from a front side of the semiconductor substrate. Thereby, the insulating film is formed on the front surface of the semiconductor substrate while the front surface of the semiconductor substrate is kept at a lower temperature than a back surface thereof.
In another aspect of the present invention, the manufacturing apparatus further comprising heating adjusting means provided between the second heating means and the front surface of the semiconductor substrate, for adjusting a degree of heating on the front surface of the semiconductor substrate.
In another aspect of the present invention, in the manufacturing apparatus, the reactive gas introducing means may adjust a temperature of the front surface of the semiconductor substrate by blowing the reactive gas against the front surface of the semiconductor substrate.
Other and further objects, features and advantages of the invention will appear more fully from the following description.
REFERENCES:
patent: 5439877 (1995-08-01), Face
patent: 5770026 (1998-06-01), Lee
patent: 5815396 (1998-09-01), Shimamura et al.
patent: 3-134175 (1991-06-01), None
Dang Phuc T.
McDermott & Will & Emery
Mitsubishi Denki & Kabushiki Kaisha
Nelms David
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