Coating apparatus – Gas or vapor deposition – With treating means
Reexamination Certificate
2002-07-17
2004-03-30
Ghyka, Alexander (Department: 2812)
Coating apparatus
Gas or vapor deposition
With treating means
C118S728000, C118S733000
Reexamination Certificate
active
06712909
ABSTRACT:
BACKGROUND OF INVENTION
1. Field of the Invention
This invention relates to a substrate processing apparatus and a method for manufacturing a semiconductor device.
2. Description of the Related Art
Conventionally, in a semiconductor manufacturing process, a CVD apparatus, an oxide film forming apparatus, a diffusion apparatus or the like is used to perform film formation of an oxide film or a thin film of Si
3
N
4
film and the like on a surface of a semiconductor substrate, which is a body to be processed, for example, a semiconductor wafer, or to perform diffusion of impurities. Recently, a substrate processing apparatus using a vertical type thermal treatment furnace is utilized in order to perform processing with high accuracy.
In a vertical type reaction furnace which is such a substrate processing apparatus, generally as shown in
FIG. 3
, a tube-shaped furnace having a heater
1
for heating is vertically disposed, and within this tube-shaped furnace, an inner reaction tube
3
and an outer reaction tube
2
made of quartz are provided. A furnace opening flange
4
which is an inlet adapter is provided at a lower end of the outer reaction tube
2
via an O-ring, and a lower end of the inner reaction tube
3
is secured to an inner circumferential surface of the furnace opening flange
4
. Moreover, a process gas introduction tube (a process gas introduction nozzle)
18
which is a process gas supply line is allowed to be in communication with a furnace opening
27
configured as an inside space of the furnace opening flange
4
.
On the other hand, many semiconductor wafers
16
which are substrates to be processed are accommodated and loaded in a boat
15
in a vertical direction with the respective wafers being in a horizontal state. The boat
15
is then placed on a boat support base
13
, and loaded into the above-said inner reaction tube
3
by allowing the boat
15
to move up by an appropriate hoisting and lowering apparatus. A furnace opening
27
is then airtightly covered with a furnace opening seal which comprises a disk-shaped cover body
7
at a lower part of the boat support base
13
via an O-ring
5
so that one closed substrate processing space (a reaction chamber)
26
is formed. Moreover, the boat support base
13
is supported by a rotation shaft
11
so that it is constructed to be rotatable by a boat rotation mechanism
10
.
An appropriate reaction gas (process gas) is introduced into the inner reaction tube
3
which constructs such a reaction chamber, from the process gas introduction tube (process gas Introduction nozzle)
18
which is a process gas supply line. The reaction furnace is constructed to perform prescribed processing, for example, of performing film formation of a thin film of SiN
4
film on silicon wafers, and the like, in the furnace using the reaction gas. In addition,
25
represents a gas exhaust tube.
In such wafer processing, the boat
15
and the boat support base
13
are allowed to rotate by the boat rotation mechanism
10
in order to improve uniformity of a CVD film generated on the wafers.
As mentioned above, the wafers
16
are loaded onto the boat
15
and heated by a heater
1
, at the same time, the process gas is introduced from the process gas introduction tube (the process gas in)
18
, and the gas passes through the wafer region to allow a gas phase chemical reaction to be performed, and an exhaust gas is exhausted from a gas exhaust tube (a process gas out)
12
whereby the wafer processing is performed.
Here, in the wafer processing wherein the boat
15
and the boat support base
13
are rotated by the boat rotation mechanism
10
in order to improve uniformity of a CVD film formed on the wafers, a conventional problem is that, when the boat rotation mechanism
10
is installed to be exposed to an inside of the reaction chamber, by-products in the wafer processing adhere to its rotation mechanism portion so that the rotation mechanism
10
is allowed to seize.
As a solution to such a disadvantage, an application of known techniques such as the following (a), (b) and (c) which prevent the process gas from entering a circumference of a rotation shaft of the rotation mechanism, is considered to be effective.
For example, (a) Japanese Patent Application Laid-Open No 2000-286204 and (b) Japanese Patent Application Laid-Open No. 6-302533 disclose a technique wherein, in order to prevent corrosion by the reaction gas of metal parts such as a boat rotation shaft and the like, a portion with concavities and convexities which interpose one another is formed at a lower surface of a boat cap made of quartz (a boat support base) and at an upper surface of a base made of quartz (a cover body), and N
2
gas is injected into a gas flow passage formed by a clearance between the concavities and convexities from a side of the rotation shaft.
Moreover, (c) Japanese Patent No. 2,691,159 discloses a technique wherein, in a construction which covers a furnace opening with a cover body
59
made of metal (stainless), as shown in
FIG. 4
, a barrier
63
made of quartz is provided around a circumference of a magnetic fluid seal unit
62
of a rotation shaft
61
, and a purge gas is introduced into a purge gas supply space
73
formed by the barrier
63
made of quartz and a lower surface of a turntable
64
so as to allow a pressure of the space to be at a positive pressure compared to a pressure in a reaction vessel thereby preventing intrusion of a reaction gas into the magnetic fluid seal unit
62
.
However, the conventional techniques (a) and (b) use the cover body made of quartz and the boat cap made of quartz for forming the gas flow passage around the circumference of the boat rotation shaft and providing the flow passage resistance (conductance) thereby resulting in a very high cost. Additionally, due to complexity of constructions such as lines and the like in a furnace opening portion of a CVD furnace, the constructions are difficult to manufacture from quartz and are liable to have insufficient strength to be able to stand.
Moreover, the conventional technique (c) has the construction wherein the barrier
63
of quartz is provided at a side of the cover body (made of metal), and the purge gas supply space
73
is formed by the barrier
63
and a rotation wall opposite to the barrier, and a purge gas is fed from the space to a side of the rotation shaft which has a narrow space, so that the purge gas has difficulty in passing through in a direction of the rotation shaft whereby a perfect purge can not be easily performed. In addition, because the barrier having a special configuration which is relatively large is constructed from quartz, the construction is also difficult to manufacture, liable to have insufficient strength to be able to stand, and at a high cost, as is the case with the conventional techniques (a) and (b). Further, in the case of the conventional technique (c), the cover body
59
is exposed to the inside of the furnace so that the cover body
59
tends to become a source of pollution of a reaction atmosphere.
Furthermore, although the cover body is preferably provided with a cooling passage therein for cooling an O-ring, as shown in the conventional technique (b), the entire cover can be cooled due to high thermal conductivity of metal. As a result, by-products adhere to the cover body so that the cover body is liable to become a source of pollution of a reaction atmosphere.
SUMMARY OF THE INVENTION
Therefore, an object of the present invention is to provide a substrate processing apparatus and a method for manufacturing semiconductor device wherewith, by resolving the problems of the prior art that semiconductor film by-products are incorporated into a boat rotation mechanism so as to allow the mechanism portion to be locked, a high quality semiconductor film can be generated with stability for a long period of time.
In order to attain the above-described object, the present invention is constructed as follows:
The invention of claim
1
resides in a substrate processing apparatus comprising: a reaction
Ghyka Alexander
Hitachi Kokusai Electric Inc.
Oliff & Berridg,e PLC
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