Semiconductor device manufacturing: process – Coating with electrically or thermally conductive material – To form ohmic contact to semiconductive material
Reexamination Certificate
2000-05-24
2001-11-20
Bowers, Charles (Department: 2813)
Semiconductor device manufacturing: process
Coating with electrically or thermally conductive material
To form ohmic contact to semiconductive material
C438S197000, C438S584000, C438S585000, C438S587000, C438S588000, C438S660000, C438S675000
Reexamination Certificate
active
06319812
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a semiconductor device manufacturing method having a step of thermally processing a gate insulating film of a transistor.
2. Description of the Background Art
A conventional manufacturing method employs a technique of effecting heat treatment on a gate insulating film of a transistor, which is formed on a semiconductor substrate, within a hydrogen atmosphere for the purpose of recovery from process damages applied to the gate insulating film forming the transistor and for the purpose of reducing a thermal stress occurring on respective interfaces between the gate insulating film and the gate electrode and between the gate insulating film and the semiconductor substrate. This technique will be referred to as “sintering” hereinafter. A semiconductor device manufacturing method using conventional sintering will now be described with reference to
FIGS. 15
to
17
.
According to the semiconductor device manufacturing method using the conventional sintering, an element isolating and insulating film
111
is formed on a semiconductor substrate
110
so that element isolating regions are formed. Then, a gate insulating film
113
and a gate electrode
114
are formed on semiconductor substrate
110
in the element formation region. Subsequently, source/drain regions
112
located on the opposite sides of gate insulating film
113
and gate electrode
114
are formed at semiconductor substrate
110
. Through these steps, a transistor of a field-effect type is formed.
Then, a protective insulating film
115
covering gate insulating film
113
and gate electrode
114
is formed. Thereafter, processing is performed to form an interlayer insulating film
116
covering protective insulating film
115
, source/drain regions
112
and element isolating and insulating film
111
. Then, contact holes reaching source/drain regions
112
are formed in interlayer insulating film
116
. Thereafter, contact plugs
117
and
118
filling the contact holes are formed.
Then, tungsten interconnections
101
and
120
are formed on contact plugs
117
and
118
as well as interlayer insulating film
116
. Contact plug
117
and tungsten interconnection
101
have resistance values which rise if they are thermally processed for a long time (several minutes) at a temperature exceeding 750° C. Thereafter, a CVD (Chemical Vapor Deposition) method or a sputtering method is performed to form an interlayer insulating film
102
which covers tungsten interconnection
101
and is made of a silicon oxide film or a silicon nitride film.
Then, a contact hole
102
a
reaching tungsten interconnection
101
is formed in interlayer insulating film
102
by a lithography technique and a dry etching technique. Then, barrier metal film made of titanium nitride is formed over the surface of contact hole
102
a
and the upper surface of interlayer insulating film
102
by the CVD method or sputtering method.
Then, the CVD method is performed so that the concavities formed by the barrier metal film is filled, and a tungsten film is formed on the barrier metal film located over the upper surface of interlayer insulating film
102
. The tungsten film is then subjected to CMP (Chemical Mechanical Polishing), dry etching or wet etching to form a tungsten plug
105
remaining only in the concavity formed by the barrier metal film.
Then, the CVD method or sputtering method is performed to form an aluminum film covering tungsten plug
105
and the barrier metal film. Then, dry etching is effected on the aluminum film and the barrier metal film after performing a lithography step so that an aluminum film
107
and a barrier metal film
106
are formed. Through the steps described above, the structure shown in
FIG. 15
is completed. If necessary, sintering within a hydrogen atmosphere in a temperature range from 370° C. to 430° C. is effected on gate insulating film
113
in the state shown in
FIG. 15
for recovering gate insulating film
113
from process damages and others so that a hillock of aluminum and a crack in the interlayer insulating film may not occur.
Thereafter, an interlayer insulating film
108
covering aluminum film
107
and barrier metal film
106
is formed. Then, the CVD method or sputtering method is performed to form an aluminum interconnection layer
109
on interlayer insulating film
108
. Through the steps described above, the structure shown in
FIG. 16
is completed. If necessary in the state shown in
FIG. 16
, sintering within a hydrogen atmosphere in a temperature range from 370° C. to 430° C. is likewise effected on gate insulating film
113
for recovering gate insulating film
113
from process damages so that a hillock of aluminum and a crack in the interlayer insulating film may not occur. Through the manufacturing process described above, the semiconductor device having the structure shown in
FIG. 16
is completed.
Through the manufacturing process described above, the sintering within the hydrogen atmosphere is performed on the structure shown in FIG.
16
. However, the temperature is low so that gate insulating film
113
cannot sufficiently recover from the process damages and others. For sufficiently recovering gate insulating film
113
from the process damages, the sintering temperature may be increased. However, such a high temperature may cause peeling (
200
) of barrier metal film
106
, occurrence of a hillock
300
of aluminum interconnection
107
and a crack
400
in interlayer insulating film
108
. This lowers the reliability of the semiconductor device. Accordingly, it is necessary to avoid peeling (
200
) of barrier metal film
106
as well as occurrence of hillock
300
of aluminum interconnection
107
and crack
400
in interlayer insulating film
108
. For this reason, it is impossible to execute sintering within in an atmosphere at a high temperature, e.g., from 450° C. to 600° C., which will be referred to as a “high-temperature sintering” hereinafter, although this high-temperature sintering can sufficiently recover gate insulating film
113
from process damages and others. Consequently, it is impossible to manufacture the semiconductor device, in which gate insulating film
113
can sufficiently recover from process damages and others.
SUMMARY OF THE INVENTION
An object of the invention is to provide a method of manufacturing a semiconductor device, which can sufficiently recover a gate insulating film from process damages and others without adversely affecting other structures.
The invention provides a method of manufacturing a semiconductor device, including the steps of forming a field-effect transistor on a semiconductor substrate, forming a first conductive interconnection causing a crystal defect if thermally processed at a temperature higher than 450° C. after formation of the transistor, wherein the method includes the step of effecting high-temperature sintering on a gate insulating film of the transistor within a hydrogen atmosphere at a temperature from 450° C. to 600° C. only after the step of forming the transistor and before the step of forming the first conductive interconnection.
According to the above manufacturing method, the sintering is performed during the manufacturing process for recovering the gate insulating film of the transistor from process damages and others. This sintering is high-temperature sintering performed in a range from 450° C. to 600° C. The process damages described above are process damages based on an interface level caused by crystal defects such as dangling bonds which occur on an interface between the gate insulating film of the field-effect transistor and the semiconductor substrate as well as on an interface between the gate insulating film and the gate electrode.
According to the above manufacturing method, since the high-temperature sintering is effected on the gate insulating film of the transistor, the gate insulating film can sufficiently recover from process damages and others. The high-temperature sintering is performed only
Anma Masatoshi
Takata Yoshifumi
Tanaka Yoshinori
Bowers Charles
Kilday Lisa
McDermott & Will & Emery
Mitsubishi Denki & Kabushiki Kaisha
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