Coating apparatus – Gas or vapor deposition – Multizone chamber
Reexamination Certificate
2001-01-24
2003-06-10
Ghyka, Alexander (Department: 2812)
Coating apparatus
Gas or vapor deposition
Multizone chamber
C118S7230MW, C118S7230MA
Reexamination Certificate
active
06576063
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an apparatus and method for use in manufacturing a semiconductor device; and, more particularly, to an apparatus and method for use in forming films on surfaces of one or more substrates such as semiconductor substrate and glass substrate and improving the film quality.
DESCRIPTION OF THE PRIOR ART
In the semiconductor industry, various kinds of films are manufactured by thermal chemical vapor deposition (CVD) method. Some of them are acceptable without further treatment but others may need pre-deposition treatment and/or post-deposition treatment in order to achieve a desired performance.
An example of the latter case requiring a further treatment is tantalum pentoxide (Ta
2
O
5
) film which is used as a capacitor insulating film for semiconductor memory and the like. In a process for forming a tantalum oxide film as an insulating film for a capacitor portion of a 64 megabit-DRAM, volatized tantalum pentaethoxide (Ta(OC
2
H
5
)
5
) gas as a precursor and oxygen gas are delivered into a reaction chamber maintaining a predetermined temperature and reacted with a Si wafer, to thereby form an oxide film.
During the deposition process of the tantalum oxide film, carbon included in the precursor, i.e., tantalum pentaethoxide (Ta(OC
2
H
5
)
5
) may be introduced into tantalum pentoxide film and, when the amount of the carbon in the film exceeds a certain level, the insulating characteristics of the film become deteriorated, thereby elevating the leakage current.
By treating the wafer in a gaseous atmosphere including oxygen as a component thereof, carbon is removed from the film in the form of carbon dioxide and the concentration of the carbon in the film becomes decreased, thereby lowering the leakage current. Further, oxygen, which is generally insufficiently incorporated into the growing film during the deposition process, may also be supplied to the film.
One of the techniques for post-processing a tantalum oxide film is a furnace annealing method. In this method, thermal treatment is performed on a deposited tantalum pentoxide (Ta
2
O
5
) film at a temperature of higher than 800° C. in an atmosphere of a gas including oxygen as a component thereof, e.g., O
2
, O
3
(ozone), N
2
O or NO. Conventionally, the deposition process is performed at a temperature equal to or lower than 500° C., which is considerably different from post-processing temperature, and, therefore, the post-deposition treatment is normally performed in a separate chamber or a separate apparatus.
In an alternative post-deposition treatment, the wafer is treated by active species generated from the plasma of gases including oxygen as a component thereof, e.g., O
2
, O
3
, N
2
O or NO.
Without such post-deposition treatments, the leakage current level may be so high that the tantalum pentoxide film cannot function properly as a capacitor insulating film.
FIG. 1
shows compositional depth profiles of the elements included in the tantalum oxide film manufactured by the above mentioned deposition process at a temperature of 470° C. The abscissa of this graph represents the depth from the surface of tantalum oxide film and the ordinate at the left provides the atom concentrations (atoms/cc) of C, H and N, and the ordinate at the right shows the secondary ion counts (counts/sec) of Ta and Si. The thickness of the tantalum oxide film is 100 Å.
As shown in
FIG. 1
, a very small amount of carbon is included at the interface between the Si wafer and the tantalum oxide film but this amount of carbon can be sufficient enough to deteriorate the film quality, i.e., entail a leakage current. In order to remove carbon from the interface to thereby reduce the amount of leakage, therefore, the substrate is processed by oxygen after the film forming. Specifically, oxygen annealing is performed at a temperature of higher than 800° C. after the film forming.
FIG. 2
provides compositional depth profiles of a tantalum oxide film formed at 450° C. and oxygen-annealed at 600° C. in a reduced pressure. The abscissa of this graph shows the depth from the surface of the substrate and the ordinate at the left shows the atom concentrations (atoms/cc) of C, H and N, and the ordinate at the right shows the secondary ion counts (counts/sec) of Ta and Si. The thickness of the tantalum oxide film is 100 Å.
It is apparent from
FIG. 2
that the concentration of hydrogen is decreased but carbon still remains at the interface.
Meanwhile, in order to meet the requirement of low temperature process, it is preferable to perform the oxygen annealing by using plasma. The temperature of wafer can be lowered to 300-400° C. during the process of using plasma. As an apparatus for plasma treatment, the so-called down-flow type apparatus appeared recently, in which the reactive gas flows downward from an upper region of the reaction chamber. This type of apparatus is preferable for achieving uniformity of film quality.
FIG. 3
shows a cross-sectional view of a down-flow type apparatus.
The apparatus includes an airtight reaction chamber
151
having walls
152
made of, e.g., stainless steel and a plasma chamber
154
, arranged above the reaction chamber for generating plasma
153
. The plasma chamber
154
has a quartz window
155
at its side and a coil
156
is arranged at the outer side of the quartz window
155
. The coil
156
generates induced magnetic fields in the plasma chamber
154
. A reactive gas inlet
157
is provided on top of the plasma chamber
154
. In the reaction chamber
151
, a substrate such as a wafer
158
is loaded on a wafer holder
159
having a built-in heater
160
for heating the wafer
158
.
The apparatus is operated as follows.
The reaction chamber
151
and plasma chamber
154
are evacuated by an exhaust pump (not shown) through an exhaust port
161
and then a reactive gas of a predetermined flow rate is introduced through the reactive gas inlet
157
into the chambers
151
,
154
. After the inner pressure of the chambers
151
,
154
becomes stabilized at a certain level, high frequency power is applied to the coil
156
from a high frequency power supply (not shown) in order to generate plasma
153
in the plasma chamber
154
and the substrate is processed by the plasma.
The plasma
153
generated in the plasma chamber
154
is spaced apart from the wafer
158
and only the neutral active species are provided to the wafer surface in the form of a down-flow
162
.
Oxygen is generally used as the reactive gas. In the apparatus shown in
FIG. 3
, oxygen radicals (O*) activated by the plasma
153
is provided in the form of a down-flow
162
to the wafer surface to react with carbon and thereby remove carbon from the surface region of the wafer
158
.
In this oxygen plasma treatment, the amount and the lifetime of the oxygen radicals may vary with the chamber pressure. Therefore, the flow rate of oxygen gas and the pressure of the plasma chamber
154
are controlled by, e.g., an exhaust pump. Typically, the process is performed under a chamber pressure of 1-100 Pa.
Such conventional type apparatus shown in
FIG. 3
may have such deficiencies as: a) release of metal particles from the walls
152
of the reaction chamber
151
which is made of metal such as stainless steel; and b) high energy particles provided by the plasma
153
.
The released metal contaminants may be incorporated into the wafer
158
or the film thereon to thereby reduce the yield.
The high energy particles from the plasma
153
may cause the metal contaminants released from the walls
152
of the reaction chamber
151
and also directly create physical and electrical defects in the wafer
158
.
The apparatus shown in
FIG. 3
is of a cold-wall type, in which only the wafer holder
159
is heated to a desired temperature.
This may entail other problems. Since the heat transfer to the wafer
158
may not be performed uniformly due to the bending and/or surface roughness of the wafer
158
, it is difficult to heat the wafer
158
uniformly in a temperature range of 500° C.±1%. In o
Kasahara Osamu
Sakai Masanori
Shima Nobuhito
Sueyoshi Mamoru
Tanaka Tsutomu
Ghyka Alexander
Hitachi Kokusai Electric Inc.
Katten Muchin Zavis & Rosenman
LandOfFree
Apparatus and method for use in manufacturing a... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Apparatus and method for use in manufacturing a..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Apparatus and method for use in manufacturing a... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3153017