U.S. patent application number 10/095072 was filed with the patent office on 2002-11-14 for substrate processing apparatus and method for manufacturing semiconductor device.
This patent application is currently assigned to HITACHI KOKUSAI ELECTRIC INC.. Invention is credited to Tometsuka, Kouji.
Application Number | 20020168854 10/095072 |
Document ID | / |
Family ID | 18986300 |
Filed Date | 2002-11-14 |
United States Patent
Application |
20020168854 |
Kind Code |
A1 |
Tometsuka, Kouji |
November 14, 2002 |
SUBSTRATE PROCESSING APPARATUS AND METHOD FOR MANUFACTURING
SEMICONDUCTOR DEVICE
Abstract
An apparatus and a method for manufacturing a semiconductor
device can prevent formation of reaction by-products at a cooled
metal flange, and can allow a maintenance period of an apparatus to
become longer. A vertical CVD apparatus as a substrate processing
apparatus for processing substrates W at a prescribed processing
temperature comprises an outer reaction quartz tube 11 and an inner
reaction quartz tube 12 provided concentrically. The outer tube 11
is vertically disposed via an O-ring 7 on an upper end of a metal
flange 20. The inner tube 12 is vertically disposed on an inner
wall of the flange 20. The O-ring 7 is cooled via the flange 20. A
lower opening 16 of the flange 20 is covered with a furnace opening
cover 32. The flange 20 is provided with a gas introducing nozzle
21 to allow a reaction gas to be introduced into the inner tube 12.
The outer tube 11 is integrally provided with an exhaust opening 22
so that a high temperature exhaust gas can be exhausted from the
exhaust opening 22 before passing through the flange 20.
Inventors: |
Tometsuka, Kouji; (Tokyo,
JP) |
Correspondence
Address: |
OLIFF & BERRIDGE, PLC
P.O. BOX 19928
ALEXANDRIA
VA
22320
US
|
Assignee: |
HITACHI KOKUSAI ELECTRIC
INC.
Tokyo
JP
|
Family ID: |
18986300 |
Appl. No.: |
10/095072 |
Filed: |
March 12, 2002 |
Current U.S.
Class: |
438/680 ;
118/724; 118/725; 438/778 |
Current CPC
Class: |
C23C 16/4411 20130101;
C23C 16/4409 20130101; C23C 16/45519 20130101; C23C 16/45591
20130101; C23C 16/4412 20130101 |
Class at
Publication: |
438/680 ;
438/778; 118/724; 118/725 |
International
Class: |
H01L 021/44; H01L
021/31; H01L 021/469; C23C 016/00 |
Foreign Application Data
Date |
Code |
Application Number |
May 10, 2001 |
JP |
2001-139542 |
Claims
what is claimed is:
1. A substrate processing apparatus comprising: a nonmetal reaction
tube; a heater that heats an interior of said reaction tube to a
prescribed processing temperature; a metal flange for disposing
said reaction tube thereon; a furnace opening cover for covering a
lower opening of said metal flange; a gas introducing opening
provided for said metal flange, for introducing a reaction gas into
said reaction tube; and an exhaust opening integrally provided for
said reaction tube, for exhausting the interior of said reaction
tube, wherein a substrate is processed in said reaction tube.
2. A substrate processing apparatus according to claim 1, wherein
said prescribed processing temperature is from 600 to 750.degree.
C., and wherein said substrate is processed under a reduced
pressure.
3. A substrate processing apparatus comprising: a nonmetal reaction
tube in which a substrate is processed; a gas introducing opening
for introducing a reaction gas into said reaction tube; a heater
that heats an interior of said reaction tube to a prescribed
processing temperature; a metal flange for disposing said reaction
tube thereon via an O-ring; a furnace opening cover for covering a
lower opening of said metal flange; a coolant flow passage provided
for said metal flange, that allows a cooling medium for cooling
said O-ring to flow therethrough; and an exhaust opening integrally
provided for said reaction tube, for exhausting the interior of
said reaction tube, wherein a gas after processing said substrate
in said reaction tube is exhausted from said exhaust opening before
passing through said O-ring.
4. A method for manufacturing a semiconductor device, comprising
forming a semiconductor device in a nonmetal reaction tube by using
a substrate processing apparatus comprising: said nonmetal reaction
tube; a heater that heats an interior of said reaction tube to a
prescribed processing temperature; a metal flange for disposing
said reaction tube thereon; a furnace opening cover for covering a
lower opening of said metal-flange; a gas introducing opening
provided for said metal flange, for introducing a reaction gas into
said reaction tube; and an exhaust opening integrally provided for
said reaction tube, for exhausting the interior of said reaction
tube;
5. A method for manufacturing a semiconductor device, comprising
forming a semiconductor device in a nonmetal reaction tube by using
a substrate processing apparatus comprising: said nonmetal reaction
tube in which a substrate is processed; a gas introducing opening
for introducing a reaction gas into said reaction tube; a heater
that heats an interior of said reaction tube to a prescribed
processing temperature; a metal flange for disposing said reaction
tube thereon via an O-ring; a furnace opening cover for covering a
lower opening of said metal flange; a coolant flow passage provided
for said metal flange, that allows a cooling medium for cooling
said O-ring to flow therethrough; and an exhaust opening integrally
provided for said reaction tube, for exhausting the interior of
said reaction tube, wherein a gas after processing said substrate
in said reaction tube is exhausted from said exhaust opening before
passing through said O-ring.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention relates to a substrate processing apparatus
and a method for manufacturing a semiconductor device, and
particularly to a substrate processing apparatus the lower
structure of which is improved,
[0003] 2. Description of the Related Art
[0004] A conventional substrate processing apparatus for performing
a method for manufacturing a semiconductor device, for example,
when taking a vertical CVD apparatus as an example and explaining
with the use of a view f or illustrating principal portions of FIG.
5, is as follows.
[0005] An outer reaction tube 1 is provided inside of a heater
which is not shown in the drawing. Within the outer reaction tube
1, there is concentrically provided an inner reaction tube 2 for
constructing a processing space 19 with an upper end being opened.
The outer reaction tube 1 and the inner reaction tube 2 are
vertically disposed on a flange 3. A lower end of the outer
reaction tube 1 is sealed by an upper end of the flange 3 via an
O-ring 17. A lower opening of the flange 3 is airtightly covered
with a furnace opening cover 19 via an O-ring 18.
[0006] The flange 3 is provided with a coolant flow passage 5 that
allows a cooling water for cooling the above-mentioned O-ring 17 to
flow therethrough, and a periphery of the O-ring 17 is
water-cooled. In addition, the furnace opening cover 19 is provided
with a coolant flow passage 6 that allows a cooling water for
cooling the above-mentioned O-ring 18 to flow therethrough, and the
periphery of the O-ring 18 is water-cooled. A boat which is not
shown in the drawing is vertically disposed on the furnace opening
cover 19, and the boat is inserted into the inner reaction tube 2.
In the boat, wafers to be processed are loaded being horizontally
oriented in a multi-stored fashion.
[0007] The flange 3 is provided with an exhaust opening 4. This
exhaust opening 4 communicates with a lower end of a cylindrical
space 13 formed as an exhaust path between the outer reaction tube
1 and the inner reaction tube 2, and through the exhaust opening 4,
interiors of the outer reaction tube 1 and the inner reaction tube
2 are exhausted. Moreover, the flange 3 is also designed to be
provided with a gas introducing nozzle in such a way that a
reaction gas is introduced into the inner reaction tube 2, which is
not shown in the drawing.
[0008] The boat is moved down via the furnace opening cover 19 by a
boat elevator which is not shown in the drawing, and wafers are
loaded onto the boat, and then, the boat is inserted into the inner
reaction tube 2 by the boat elevator. After the furnace opening
cover 19 completely covers a lower end of the flange 3, the
interiors of the outer reaction tube 1 and the Inner reaction tube
2 are exhausted to a reduced pressure.
[0009] While supplying a reaction gas into the inner reaction tube
2 from the gas introducing nozzle, the reaction gas is exhausted
from the exhaust opening 4. The interior of the inner reaction tube
2 is heated to a prescribed temperature, and a film is formed onto
a surface of the wafers. After completing the film formation, an
inert gas is introduced from the gas introducing nozzle so that the
atmosphere inside of the outer reaction tube 1 and the inner
reaction tube 2 is substituted for the inert gas, and then, the
interiors of the outer and inner tubes 1 and 2 are returned to a
normal pressure to draw out the boat.
[0010] In the mean time, in contrast to the above-mentioned CVD
apparatus, a process, such as annealing, diffusion or oxidation, in
a furnace of a substrate processing apparatus (hereafter referred
to as a diffusion furnace and the like) is performed at a higher
temperature (1000.degree. C. or more). In addition, there are many
devices wherein metal contamination should be avoided. For these
reasons, a metal member can not be used inside of a furnace such as
a diffusion furnace and the like. All of a reaction tube, a flange,
a cover body and the like are typically formed of quartz without
using a metal part.
[0011] On the other hand, a process in the CVD apparatus is
performed at a lower temperature (about 600 to 750.degree. C.) so
that, even If a metal member is used in a furnace, a malfunction is
not caused to the extent as In the diffusion furnace and the like.
Therefore, in general, metal such as stainless steel, aluminum
alloy or the like which has more superior machinability and cost
efficiency is used for the flange and the furnace opening cover
while quartz is used for the outer reaction tube 1 and the inner
reaction tube 2.
[0012] In this way, a metal member is used for some parts of the
furnace in a vertical CVD apparatus, but a relation between the
metal flange and an exhaust gas particularly causes a problem In
this case.
[0013] In the conventional vertical CVD apparatus, as mentioned
above, the metal flange 3 is provided with the exhaust opening 4,
and the outer reaction tube 1 and the metal flange 3 are sealed by
the O-ring 17. As a material of the O-ring 17, there is generally
used a fluororubber or the like which has durability and
elasticity. In the case of fluororubber, when using this under a
reduced pressure at a low temperature of about 600 to 750.degree.
C., a component such as water and the like is released by heating
so that an organic contaminant referred to as degasification is
generated. Therefore, the metal flange 3 is provided with the
coolant flow passage 5 to allow cooling water to flow therethrough
so that the periphery of the O-ring 17 is cooled.
[0014] However, when allowing cooling water to flow through the
coolant flow passage 5 with which the metal flange 3 is provided In
order to water-cool the O-ring 17, the entire metal flange 3
including the exhaust opening 4 becomes cooled, because the metal
flange 3 formed integrally with the exhaust opening 4 is formed of
metal such as stainless steel and the like. If the entire metal
flange 3 has been cooled, the reaction gas is cooled by contact
with the metal flange 3 when being exhausted from the exhaust
opening 4 provided for the metal flange 3 so that reaction
by-products adhere to a metal flange inner wall. Many of the
reaction byproducts adhere particularly to the vicinity of the
exhaust opening 4. The reaction by-products which have adhered peel
off to be particles which contaminate the reaction atmosphere so
that there is a fear of adherence of the particles onto the
substrates. The adherence of the particles onto the substrates
tends to become a cause of defects in a product (a semiconductor
device).
[0015] Hence, in order to take measures against the by-products, an
attempt to heat the portion of the metal flange 3 except the
vicinity of the O-ring 17 has been made. However, a metal component
is released from a metal surface by heating and an organic
contaminant referred to as degasification is generated, which
results in metal contamination. In CVD, metal contamination is
undesirable, although the suppression of the metal contamination is
not so required to the extent as in the diffusion furnace and the
like. Therefore, a measure to heat a metal flange can not be
adopted. As a result, it is impossible to effectively prevent the
reaction by-products from adhering to the metal flange 3.
[0016] Thus, it is impossible to effectively prevent the reaction
by-products from adhering to the inner wall of the metal portion
due to the cooling phenomenon of the metal portion. As a result, in
order to remove the reaction by-products, there has been a problem
that a maintenance period of an apparatus becomes short.
SUMMARY OF THE INVENTION
[0017] An object of the present invention is to provide a substrate
processing apparatus and a method for manufacturing a semiconductor
device wherewith, by resolving the problems with the prior art
noted in the foregoing, reaction by-products are less apt to adhere
to a metal portion so that a maintenance period is long
[0018] A first invention resides in a substrate processing
apparatus comprising: a nonmetal reaction tube; a heater that heats
an interior of the reaction tube to a prescribed processing
temperature; a metal flange for disposing the reaction tube
thereon, that constitutes a furnace opening of the reaction tube: a
furnace opening cover for covering the furnace opening of the metal
flange: a gas introducing opening provided for the metal flange,
for introducing a reaction gas into the reaction tube; and an
exhaust opening integrally provided for the reaction tube, for
exhausting the interior of the reaction tube, wherein a substrate
is processed In the reaction tube.
[0019] While being supplied into a reaction tube from a gas
introducing opening, a reaction gas is exhausted from an exhaust
opening. This exhaust opening is integrally provided for the
reaction tube disposed on a metal flange. Accordingly, even if the
metal flange is cooled, the reaction gas is exhausted before the
reaction gas reaches the metal flange so that the reaction gas
which remains in a high temperature state without being cooled by
the metal flange is exhausted to an outside. As a result, it is
possible to effectively prevent reaction by-products resulting from
a cooling phenomenon from adhering to a periphery of the exhaust
opening or an inner wall of the metal flange so that particles are
not generated onto a substrate during processing the substrate.
[0020] In the above-mentioned invention, it is preferable that the
prescribed processing temperature be from 600 to 750.degree. C. and
that the substrate be processed under a reduced pressure. A typical
process for processing a substrate at a temperature from 600 to
750.degree. C. under a reduced pressure includes a CVD process. In
the case of performing a process at such temperatures, even if a
metal member such as a metal flange and the like is used at a lower
portion of an apparatus (a lower furnace portion), a problem of
metal contamination does not arise because the temperature is
low.
[0021] A second invention resides in a substrate processing
apparatus comprising: a nonmetal reaction tube In which a substrate
is processed; a gas introducing opening for introducing a reaction
gas into the reaction tube; a heater that heats an interior of the
reaction tube to a prescribed processing temperature; a metal
flange for disposing the reaction tube thereon via an O-ring, that
constitutes a furnace opening of the reaction tube; a furnace
opening cover for covering the furnace opening of the metal flange;
a coolant flow passage provided for the metal flange, that allows a
cooling medium for cooling the O-ring to flow therethrough: and an
exhaust opening integrally provided to the reaction tube, for
exhausting the interior of the reaction tube, wherein a gas after
processing the substrate in the reaction tube is exhausted from the
exhaust opening before passing through the O-ring.
[0022] Since an exhaust opening is provided to a reaction tube
itself disposed on a metal flange, a reaction gas is exhausted from
the exhaust opening provided to the reaction tube before the
reaction tube passes through an O-ring disposed between the
reaction tube and the metal flange. Accordingly, the reaction gas
which remains at a high temperature is exhausted from the exhaust
opening without being cooled by contact with the metal flange which
becomes cooled as the O-ring is cooled by flowing a cooling medium.
As a result, it is possible to effectively prevent reaction
by-products resulting from the cooling from adhering to a periphery
of the exhaust opening or an inner wall of the metal flange.
[0023] A third invention reside in a method for manufacturing a
semiconductor device, comprising forming a semiconductor device in
a nonmetal reaction tube by using a substrate processing apparatus
comprising; the nonmetal reaction tube; a heater that heats an
interior of the reaction tube to a prescribed processing
temperature; a metal flange for disposing the reaction tube
thereon, that constitutes a furnace opening of the reaction tube: a
furnace opening cover for covering the furnace opening of the metal
flange; a gas introducing opening provided for the metal flange,
for introducing a reaction gas into the reaction tube; and an
exhaust opening integrally provided for the reaction tube, for
exhausting the interior of the reaction tube.
[0024] A fourth invention resides in a method for manufacturing a
semiconductor device, comprising forming a semiconductor device in
a nonmetal reaction tube by using a substrate processing apparatus
comprising: the nonmetal reaction tube in which a substrate is
processed: a gas introducing opening for introducing a reaction gas
into the reaction tube: a heater that heats an interior of the
reaction tube to a prescribed processing temperature; a metal
flange for disposing the reaction tube thereon via an O-ring, that
constitutes a furnace opening of the reaction tube; a furnace
opening cover for covering the furnace opening of the metal flange;
a coolant flow passage provided for the metal flange, that allows a
cooling medium for cooling the O-ring to flow therethrough; and an
exhaust opening integrally provided for the reaction tube, for
exhausting the interior of the reaction tube, wherein a gas after
processing the substrate in the reaction tube is exhausted from the
exhaust opening before passing through the O-ring.
[0025] According to the third and fourth inventions, since an
exhaust opening is provided for a reaction tube disposed on a metal
flange, a reaction gas is exhausted from the exhaust opening
provided for the reaction tube before the reaction gas passes
through an O-ring disposed between the reaction tube and the metal
flange. Accordingly, the reaction gas which remains at a high
temperature is exhausted from the exhaust opening without being
cooled by contact with the metal flange which becomes cooled as the
O-ring is cooled by allowing a cooling medium to flow. As a result,
it is possible to effectively prevent reaction by-products
resulting from the cooling from adhering to a periphery of the
exhaust opening or an inner wall of the metal flange so that a high
quality semiconductor device can be manufactured without any
defects due to adherence of particles.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] FIG. 1 is a schematic view for illustrating a construction
of a vertical CVD apparatus adapted to be a semiconductor
manufacturing apparatus for performing a method for manufacturing a
semiconductor device according to the present invention:
[0027] FIG. 2 is a view for Illustrating detailed principal
portions of a lower construction of a vertical CVD apparatus
according to an embodiment;
[0028] FIG. 3 is a view for illustrating detailed principal
portions of a lower construction of a vertical CVD apparatus
according to a modified example of an embodiment;
[0029] FIG. 4 is a view for illustrating a construction of an
exhaust system according to an embodiment; and
[0030] FIG. 5 is a view for illustrating detailed principal
portions of a lower construction of a vertical CVD apparatus
according to a conventional example.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0031] Embodiments of the present invention will be described
below.
[0032] FIG. 1 shows a schematic view of a construction of an
embodiment of a vertical CVD apparatus adapted to be a
semiconductor manufacturing apparatus for performing a method for
manufacturing a semiconductor device.
[0033] Inside of a heater 10 which is closed at its upper portion,
there is provided a nonmetal outer reaction tube; for example, an
outer reaction tube 11 made of quartz, and within the outer
reaction tube 11, there is concentrically provided a nonmetal inner
reaction tube with an upper end being opened, for example, an inner
reaction tube 12 made of quartz. Within the inner reaction tube 12,
there is constructed a processing space 25 in which wafers W are
processed. The outer reaction tube 11 and the inner reaction tube
12 are vertically disposed on a metal flange 20, and the outer
reaction tube 11 and the metal flange 20 are sealed therebetween by
an O-ring 7. A lower end of the metal flange 20 is airtightly
covered with a furnace opening cover 32 made of metal, for example
made of stainless steel or aluminum alloy, via an O-ring 8. A boat
30 made of quartz which is vertically disposed on the furnace
opening cover 32 via a cap 31 made of quartz, is inserted into the
processing space 25 within the inner reaction tube 12. In the boat
30, wafers W as a substrate to be processed are loaded being
horizontally oriented in a multi-storied fashion. The boat 30 is
designed to rotate while the furnace opening cover 32 is not a
rotatable system. Rotation of the boat 30 is performed by a boat
rotation mechanism 33 which is attached to an outside of the
furnace opening cover 32.
[0034] The reason why metal such as stainless steel and the like
rather than quartz is used for a flange is that the flange is
employed for a CVD apparatus which is operated at a relatively low
temperature and that metal has a better sealing property and cost
efficiency than quartz In addition, the metal flange 20 is so easy
to machine as to be easily connected to a reaction gas introducing
nozzle 21 made of metal. Moreover, the metal flange 20 can
sufficiently bear own weight of the inner reaction tube 12 and the
outer reaction tube 11.
[0035] The reaction gas introducing nozzle 21 as a gas introducing
opening is adapted to be provided at a peripheral wall portion of
the metal flange 20 so that a reaction gas can be introduced into
the processing space 25 within the inner reaction tube 12. In
addition, an exhaust opening 22 is adapted to be integrally
provided for the outer reaction tube 11 rather than for the metal
flange 20 so as to exhaust interiors of the outer reaction tube 11
and the inner reaction tube 12. The exhaust opening 22 is provided
at one side of a lower portion of the outer reaction tube 11 in
such a way that the exhaust opening 22 is connected to a lower
portion of a cylindrical space 15 formed between the outer reaction
tube 11 and the inner reaction tube 12.
[0036] In this vertical CVD apparatus, with regard to a vertical
relation between the exhaust opening 22 provided for the outer
reaction tube 11 and the O-ring 7 for sealing the outer reaction
tube 11 and the metal flange 20 therebetween, the exhaust opening
22 is located above the O-ring 7. Accordingly, the reaction gas
which is exhausted downwardly in the cylindrical space 15 as
indicated by arrows does not pass through either the metal flange
20 or the O-ring 7 so that the reaction gas can be exhausted before
passing through the flange 20 and the O-ring 7.
[0037] Furthermore, a back purge gas introducing nozzle 23 is
adapted to be provided at the other side of the lower portion of
the outer reaction tube 11 so as to introduce a back purge gas into
the outer reaction tube 11. Here, the exhaust opening 22 provided
at the lower portion of the outer reaction tube 11 and the back
purge gas introducing nozzle 23 are integrally formed with the
outer reaction tube 11 with fused quartz. The metal flange 20 is
made of, for example, stainless steel or aluminum alloy.
[0038] The furnace opening cover 32 is disposed on an underside of
the cap 31. The furnace opening cover 32 is in intimate contact
with a surface under an enlarged outer diameter of the metal flange
20 so that the furnace opening cover 32 airtightly seals via an
O-ring 8 a lower opening 16 of the metal flange 20 that becomes a
furnace opening. At an underside of this furnace opening cover 32
(outside of the processing space 25), there is provided a boat
elevator board which is not shown in the drawing, and the boat 30
is inserted into or drawn out from the processing space 25 by
allowing this boat elevator board to move up or down. The boat
rotation mechanism 33 can rotate the boat 30 within a horizontal
surface via the cap 31.
[0039] FIG. 2 shows a view of detailed principal portions of a
lower construction of the vertical CVD apparatus of FIG. 1. This
view of the principal portions is a side sectional view
illustrating a state in which the lower opening 16 of the metal
flange 20 is covered with the furnace opening cover 32.
[0040] The exhaust opening 22 is integrally provided at the lower
portion of the outer reaction tube 11. In addition, the outer
reaction tube 11 provided integrally with this exhaust opening 22
is vertically disposed via the O-ring 7 on a horizontal flange
portion 28 provided at an upper end of the metal flange 20.
[0041] On an inner peripheral wall of the metal flange 20, there is
provided an annular convex portion 24 which extends radially
inwardly from the inner wall, and the inner reaction tube 12 is
vertically disposed on the annular convex portion 24, At a lower
end of the metal flange 20, there is provided a horizontal flange
portion 26, and at the same time, the outer diameter of the furnace
opening cover 32 is set in accordance with the flange portion 26.
The metal flange 20 and the furnace opening cover 32 are sealed
therebetween via the O-ring 8.
[0042] The metal flange 20 is provided with a coolant flow passage
27 that allows a cooling water for cooling the above-mentioned
O-ring 7 to flow therethrough, so that a periphery of the O-ring 7
is water-cooled. In addition, the furnace opening cover 32 is
provided with a coolant flow passage 34 that allows a cooling water
for cooling the above-mentioned O-ring 8 to flow therethrough, so
that a periphery of the O-ring 8 is water-cooled.
[0043] The boat 30 is moved down by a boat elevator which is not
shown in the drawing, and in the boat 30, wafers W are loaded being
horizontally oriented in a multi-storied fashion, and then, the
boat 30 is inserted Into the processing space 25 within the inner
reaction tube 12 by the boat elevator. After the furnace opening
cover 32 completely covers a lower end of the metal flange 20 via
the O-ring a, the processing space 25 within the inner reaction
tube 12 and the outer reaction tube 11 is exhausted to a reduced
pressure. This exhaustion is performed with a vacuum pump (not
shown in the drawing) which communicates with the exhaust opening
22.
[0044] A reaction gas is introduced through the reaction gas
introducing nozzle 21 which is provided at the peripheral wall
portion of the metal flange 20. The reaction gas for generating a
required thin film includes SiH.sub.4, Si.sub.2H.sub.6,
SiH.sub.2Cl.sub.2, NH.sub.3, PH.sub.3, N.sub.2 and the like. The
reaction gas flows through the interior of the inner reaction tube
12 upwardly as indicated by an arrow, and then, the reaction gas
flows through the space 15 between the outer reaction tube 11 and
the inner reaction tube 12 downwardly as indicated by arrows so as
to be exhausted through the exhaust opening 22 to the outside.
[0045] In this way, while supplying the reaction gas into the
processing space 25 from the reaction gas introducing nozzle 21,
the reaction gas is exhausted from the gas exhaust opening 22. The
processing space 25 is heated by the heater 10 to 600 to
750.degree. C. which is a wafer processing temperature, and then, a
chemical vapor deposition is performed on the wafers W under a
reduced pressure of 10 to 100 Pa to perform film formation of a
semiconductor film such as nitride film and the like on the
surface. After completing the film formation, an inert gas, for
example, N.sub.2 gas is introduced from the back purge gas
introducing nozzle 23 so that the atmosphere inside of the reaction
tubes 11 and 12 is substituted for the inert gas, and then, the
interiors of the outer and Inner tubes 11 and 12 are returned to a
normal pressure. Next, the boat 30 is moved down to draw out the
wafers W on which the film formation has been completed.
[0046] According to the embodiment, the outer reaction tube 11 made
of quartz is integrally provided with the exhaust opening 22, In
addition, the outer reaction tube 11 is connected to the metal
flange 20 at a position below the exhaust opening 22 via the O-ring
7. Therefore, in contrast to the case where the outer reaction tube
is connected at a position above the exhaust opening via the O-ring
to the metal flange that is integrally provided with the exhaust
opening 22, neither the exhaust opening 22 nor an exhaust path
leading to the exhaust opening 22 can be cooled. As a result, It is
possible to effectively prevent reaction by-products from adhering
to a periphery of the exhaust opening 22 due to heating of the
exhaust opening 22 by thermal conductivity from the processing
space 25 within the wall of the outer reaction tube 11. Moreover,
since the reaction by-products do not adhere to the periphery of
the exhaust opening 22, there is no necessity to heat the metal
flange for taking measures against the by-products. This can also
avoid metal contamination due to bakeout of the metal surface.
[0047] Incidentally, the above-mentioned embodiment of FIG. 1 and
FIG. 2 is constructed in such a way that the outer reaction tube 11
is supported by the upper end flange portion 28 of the metal flange
20 and that the inner reaction tube 12 is supported by the convex
portion 24 of the metal flange 20. In this construction, a step
which exposes a metal portion of the metal flange 20 is formed in
the vicinity of the convex 24. That is, there is a fear of
adherence of by-products to the step portion R, as indicated by a
circle in FIG. 2, wherein the metal of the convex 24 at the bottom
portion of the space 15 which is the exhaust path is exposed. If
by-products containing a C1 component adheres to this portion, the
C1 component captures metal ions so as to cause the metal to
corrode. If the by-products in which the metal ions are
incorporated peel off and are blown up, the by-products may lead to
a cause of metal contamination.
[0048] Accordingly, an embodiment as shown in FIG. 3 is designed in
such a way that the outer reaction tube 11 is supported by an inner
reaction tube 42 rather than by a metal flange 40 and that the
metal flange 40 supports only the inner reaction tube 42 at an
upper flange portion of the metal flange 40. That is, a flange 43
of the inner reaction tube 42 at a lower end of the inner reaction
tube 42 is radially outwardly enlarged, and the outer reaction tube
11 is vertically disposed and supported via the O-ring 7 on the
enlarged flange 43. In addition, the inner reaction tube 42 is
adapted to be vertically disposed and supported via an O-ring 9 on
a metal flange 40 to thereby allow the aforementioned step portion
not to be generated. According to this, addition of only one O-ring
9 allows the space 15 being the exhaust path to be formed only by
the outer reaction tube 11 which is made of quartz and the inner
reaction tube 42 which is made of quartz, thereby exposing no metal
surface to the space 15 so that no by-products can adhere to the
periphery of the exhaust opening.
[0049] In the mean time, a metal exhaust tube which leads to a
vacuum pump is connected to the exhaust opening 22 with which the
outer reaction tube 11 is integrally provided, and there may be a
problem that reaction by-products adhere to the metal exhaust tube
and the vicinity of the connecting portion. In this regard, an
exhaust system of the present embodiment as shown in FIG. 4
comprises the exhaust opening 22 with which the outer reaction tube
11 is integrally provided, a metal pipe 37 leading to a vacuum
pump, an O-ring 35 being located between the flanges of the exhaust
opening 22 and the metal pipe 37, a clamp 36 for clamping the
flanges together, and a heater 38 for heating the metal pipe
37,
[0050] A lower limit temperature at which no by-products adhere is
about 15020 C. As mentioned above, the exhaust opening 22 is heated
to the extent of the end flange of the exhaust opening 22 by heat
which transfers along the inner wall of the outer reaction tube 11
so that the end flange is maintained at a temperature at which no
by-products adhere. This temperature is about T.sub.2=400.degree.
C. If the metal pipe 11 is maintained at about T.sub.3=150.degree.
C. with the heater 38, the connecting portion in which the O-ring
35 is located can be maintained at about T.sub.2200.degree. C.
Accordingly, no reaction by-products adhere to the metal pipe 11
and the connecting portion connected to the exhaust opening 22, not
to mention the exhaust opening 22. If the exhaust opening 22 is too
long, it is difficult to maintain the end side of the exhaust
opening 22 at a temperature at which no reaction by-products
adhere. A length L of the exhaust opening 22 wherein the
by-products are difficult to adhere is about 200 mm.
[0051] As mentioned above, according to the present embodiments, in
a vertical CVD apparatus in which a CVD film is formed on wafers
under a reduced pressure, an outer reaction tube which is made of
quartz is integrally provided with an exhaust opening to thereby
minimize exposure of a metal part to an exhaust path or to thereby
result in no exposure of the metal part to the exhaust path.
Accordingly, when generating a semiconductor film on wafers,
adherence of by-products to the metal part can be reduced to
thereby allow particle generation and metal contamination resulting
from by-products peeling off to be substantially reduced so that a
high quality semiconductor device can be manufactured. Moreover,
the integration of the exhaust opening with the outer reaction tube
is easily performed with fused quartz so that a high quality
semiconductor device can be manufactured at low cost.
[0052] In addition, the present invention which is applicable to
general film formation via a vapor phase reaction is particularly
effective in taking measures against reaction by-products during
film formation of an SiN film and a TEOS film particularly because
an exhaust gas which has the property of solidifying when cooled at
a temperature of 100.degree. C. or less can be exhausted without
cooling.
[0053] Moreover, in the above explanation, the case has been
explained In which the present invention is applied to a substrate
processing apparatus having a reaction tube made of quartz as a
nonmetal reaction tube. However, the present invention can also be
applied to a substrate processing apparatus having a reaction tube
made of nonmetal but quartz.
[0054] According to the present invention, adherence of reaction
by-products to a metal flange can be effectively prevented, and
particle generation and metal contamination can be reduced.
Accordingly, a high quality semiconductor device can be
manufactured with long-term stability, and a maintenance period of
an apparatus can be longer.
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