U.S. patent application number 15/128139 was filed with the patent office on 2017-03-30 for substrate processing apparatus and furnace opening cover.
This patent application is currently assigned to HITACHI KOKUSAI ELECTRIC INC.. The applicant listed for this patent is HITACHI KOKUSAI ELECTRIC INC.. Invention is credited to Naonori AKAE, Shinya MORITA, Kosuke TAKAGI, Keishin YAMAZAKI.
Application Number | 20170088948 15/128139 |
Document ID | / |
Family ID | 54194900 |
Filed Date | 2017-03-30 |
United States Patent
Application |
20170088948 |
Kind Code |
A1 |
TAKAGI; Kosuke ; et
al. |
March 30, 2017 |
SUBSTRATE PROCESSING APPARATUS AND FURNACE OPENING COVER
Abstract
Provided is a technique capable of suppressing the occurrence of
by-products by suppressing adhesion of the by-products. A substrate
processing apparatus includes: a reaction tube where a substrate is
processed; a furnace opening unit disposed at a lower end of the
reaction tube and having an upper surface and an inner
circumferential surface, the furnace opening unit including: a
concave portion disposed on the upper surface; and a convex portion
having at least one notch connecting the concave portion to the
inner circumferential surface; a cover covering at least the inner
circumferential surface with a predetermined gap therebetween; and
a gas supply unit configured to supply a gas to the concave
portion.
Inventors: |
TAKAGI; Kosuke; (Toyama-shi,
JP) ; MORITA; Shinya; (Toyama-shi, JP) ; AKAE;
Naonori; (Toyama-shi, JP) ; YAMAZAKI; Keishin;
(Toyama-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
HITACHI KOKUSAI ELECTRIC INC. |
Tokyo |
|
JP |
|
|
Assignee: |
HITACHI KOKUSAI ELECTRIC
INC.
Tokyo
JP
|
Family ID: |
54194900 |
Appl. No.: |
15/128139 |
Filed: |
February 16, 2015 |
PCT Filed: |
February 16, 2015 |
PCT NO: |
PCT/JP2015/054138 |
371 Date: |
September 22, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01L 21/67109 20130101;
C23C 16/4409 20130101; C23C 16/4401 20130101; H01L 21/67126
20130101 |
International
Class: |
C23C 16/44 20060101
C23C016/44 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 26, 2014 |
JP |
2014-063073 |
Claims
1. A substrate processing apparatus comprising: a reaction tube
where a substrate is processed; a furnace opening unit disposed at
a lower end of the reaction tube and having an upper surface and an
inner circumferential surface, the furnace opening unit comprising:
a concave portion disposed on the upper surface; and a convex
portion having at least one notch connecting the concave portion to
the inner circumferential surface; a cover covering at least the
inner circumferential surface with a predetermined gap
therebetween; and a gas supply unit configured to supply a gas to
the concave portion.
2. The substrate processing apparatus of claim 1, further
comprising a cap dosing a lower end of the furnace opening unit
with a gap between the cap and the cover.
3. The substrate processing apparatus of claim 1, wherein the cover
comprises: a side surface portion disposed along the inner
circumferential surface; and a horizontal portion perpendicular to
the side surface portion.
4. The substrate processing apparatus of claim 3, wherein the
horizontal portion is disposed between the convex portion and the
reaction tube and extends toward the furnace opening unit.
5. The substrate processing apparatus of claim 3, wherein the
furnace opening unit further comprises a projection for mounting
the cover, and the cover further comprises an opening where the
projection is hooked, the opening disposed at the side surface
portion.
6. The substrate processing apparatus of claim 5, wherein the
horizontal portion extends toward a center of the furnace opening
unit.
7. The substrate processing apparatus of claim 3, wherein the cover
further comprises a trench spatially connected to the concave
portion at the horizontal portion.
8. The substrate processing apparatus of claim 5, wherein the cover
further comprises a protrusion disposed on the side surface portion
and protruding toward the inner circumferential surface.
9. The substrate processing apparatus of claim 1, wherein the cover
comprises a plurality of cover members disposed along a
circumferential direction.
10. The substrate processing apparatus of claim 5, wherein the
cover further comprises a plurality of projections having unequal
distances therebetween.
11. The substrate processing apparatus of claim 1, wherein the gas
supply unit comprises; a first gas supply unit connected to a first
location of the furnace opening unit; and a second gas supply unit
connected to a second location of the furnace opening unit opposed
to the first location.
12. The substrate processing apparatus of claim 1, further
comprising a cleaning gas supply unit configured to supply a
cleaning gas to the furnace opening unit.
13. A furnace opening cover covering an inner circumferential
surface of a furnace opening unit disposed at a lower end of a
reaction tube of a substrate processing apparatus, the furnace
opening cover comprising: an opening hooked to a projection
disposed on the inner circumferential surface; and a protrusion
protruding toward the inner circumferential surface.
Description
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS
[0001] This non-provisional U.S. patent application claims priority
under 35 U.S.C. .sctn.119 of Japanese Patent Application No.
2014-063073, filed on Mar. 26, 2014, and international Patent
Application No. PCT/JP2015/054138, filed on Feb. 16, 2015, in WIPO,
the entire contents of which are hereby incorporated by
reference.
BACKGROUND
[0002] 1. Field
[0003] The present disclosure relates to a substrate processing
apparatus and a furnace opening cover.
[0004] 2. Description of the Related Art
[0005] A substrate processing apparatus is known as one example of
a semiconductor manufacturing apparatus. The substrate processing
apparatus includes a reaction tube here substrates are housed; a
gas introduction pipe for supplying a process gas into the reaction
tube; a healing unit configured to heat the substrates in the
reaction tube; an exhaust pipe for exhausting the inner atmosphere
of the reaction tube; and a substrate retainer loaded into the
reaction tube with the substrates supported therein. After the
substrate retainer supporting the substrates is loaded into the
reaction tube through a lower end (furnace opening) of the reaction
tube, a process gas is supplied into the reaction tube through the
gas introduction pipe with the substrates heated by the heating
unit, thereby forming a desired film on the substrates (refer to
Patent Document 1).
RELATED ART DOCUMENT
Patent Document
[0006] Patent Document 1: Japanese Patent Publication No.
2009-99608
[0007] The substrate processing apparatus described above may
further include a metallic furnace opening unit installed at the
lower end of the reaction tube. The gas introduction pipe may be
fixed to the furnace opening unit. When by-products adhere to the
inner circumference of the furnace opening unit, particles may
occur.
SUMMARY
[0008] Described herein is a technique capable of suppressing the
occurrence of particles.
[0009] According to one aspect described herein, a substrate
processing apparatus may include: a reaction tube where a substrate
is processed; a furnace opening unit disposed at a lower end of the
reaction tube and having an upper surface and an inner
circumferential surface, the furnace opening unit including: a
concave portion disposed on the upper surface; and a convex portion
having at least one notch connecting the concave portion to the
inner circumferential surface; a cover covering at least the inner
circumferential surface with a predetermined gap therebetween; and
a gas supply unit configured to supply a gas to the concave
portion.
[0010] According to the technique described herein, it is possible
to suppress the occurrence of particles.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 schematically illustrates a substrate processing
apparatus according to a first embodiment described herein.
[0012] FIG. 2 is a plan view of a furnace opening unit 209
according to the first embodiment described herein.
[0013] FIG. 3 is a perspective view illustrating a state in which a
furnace opening cover 320 is mounted on the furnace opening unit
209 according to the first embodiment described herein.
[0014] FIG. 4 is a perspective view illustrating a cross-section
taken along the line B-B line of FIG. 3.
[0015] FIG. 5 is a cross-sectional view illustrating surroundings
of an inert gas supply port 321 at a lower end of the reaction tube
according to the first embodiment described herein.
[0016] FIG. 6 is a flowchart illustrating a film forming step and a
cleaning step which can be performed in the substrate processing
apparatus according to the first embodiment described herein.
[0017] FIG. 7 is a perspective view illustrating a cross-section of
the lower end portion of the reaction tube of the substrate
processing apparatus according to the first embodiment described
herein.
[0018] FIG. 8 schematically illustrates a substrate processing,
apparatus according to a second embodiment described herein.
[0019] FIG. 9 is a plan view of a furnace opening unit 409
according to the second embodiment described herein.
[0020] FIG. 10 is a perspective view illustrating a state in which
a furnace opening cover 520 is mounted on the furnace opening unit
409 according to the second embodiment described herein.
[0021] FIG. 11A is a perspective view of a furnace opening cover
member 520-1 according to the second embodiment described herein,
and FIG. 11B is a cross-sectional view taken along the line C-C of
FIG. 11A.
[0022] FIG. 12 is a perspective view illustrating a cross-section
taken along the line D-D of FIG. 10.
[0023] FIG. 13 is a cross-sectional view illustrating surroundings
of an inert gas supply port 321 at a lower end portion of the
reaction tube according to the second embodiment described
herein.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0024] Hereafter, a first embodiment described herein will be
described with reference to the accompanying drawings.
[0025] As illustrated in FIG. 1, a process furnace 202 includes a
heater 207 as a heating unit (heating device). The heater 207 has a
cylindrical shape and is vertically installed while being supported
by a heater base (not illustrated).
[0026] A process tube 203 serving as a reaction tube is installed
in the heater 207 so as to be concentric with the heater 207. The
process tube 203 is formed of a heat-resisting material such as
quartz (SiO.sub.2) and carbon silicon (SiC), and is cylindrical
with a closed upper end and an open lower end. A process chamber
201 is disposed in a hollow inner portion of the process tube 203.
The process chamber 201 may house a plurality of wafers 200 as
substrates therein, the wafers 200 being horizontally laid and
vertically stacked in multiple stages by a boat 217 serving as a
substrate retainer.
[0027] An exhaust pipe 231 for exhausting the inner atmosphere of
the process chamber 201 is installed at a lower portion of the
process tube 203. A vacuum pump 246 serving as a vacuum exhauster
is connected to the exhaust pipe 231 with a pressure sensor 245 and
an APC (Automatic Pressure Controller) valve 243 interposed
therebetween. The pressure sensor 245 serves as a pressure
detector, and the APC valve 243 serves as a pressure regulator. By
adjusting an opening degree of the APC valve 243 based on a
pressure detected by the pressure sensor 245, the process chamber
201 may be vacuum-exhausted by the vacuum pump 246 such that the
inner pressure of the process chamber 201 becomes a predetermined
pressure (vacuum degree). The APC valve 243 may vacuum-exhaust the
process chamber 201 through an opening/closing operation or suspend
the vacuum exhaust, and adjust the inner pressure of the process
chamber 201 by adjusting the opening degree.
[0028] A furnace opening unit 209 is installed at the lower end of
the process tube 203 so as to be concentric with the process tube
203. The furnace opening unit 209 is also referred to as an inlet
or manifold. The furnace opening unit 209 is formed of a metal such
as stainless steel (SUS) or nickel (Ni) alloy, and cylindrical with
an open upper end and an open lower end. A gas introduction unit
described later is fixed to the furnace opening unit 209. The
furnace opening unit 209 supports the process tube 203. An O-ring
220a serving as a seal member is installed between the furnace
opening unit 209 and the process tube 203. The process tube 203 and
the furnace opening unit 209 constitute a reaction container.
[0029] A first nozzle 233a serving as a first gas introduction
unit, a second nozzle 233b serving as a second gas introduction
unit, and a third nozzle 233e serving as a third gas introduction
unit are installed at the furnace opening unit 209 so as to
penetrate the sidewall of the furnace opening unit 209. Each of the
first to third nozzles 233a, 233b and 233e is L-shaped with a
horizontal portion and a vertical portion. The horizontal portions
of the first to third nozzles 233a, 233b and 233e are connected to
the sidewall of the furnace opening unit 209. The vertical portions
of the first to third nozzles 233a, 233b and 233e are disposed in
an annular space between the inner wall of the process tube 203 and
the wafer 200, and extended along the inner wall of the upper
portion from the lower portion of the process tube 203. First to
third gas supply holes 248a, 248b and 248e for supplying gases are
installed at side surfaces of the vertical portions of the first to
third nozzles 233a, 233b and 233e, respectively.
[0030] A temperature sensor 263 serving as a temperature detector
is installed in the process rube 203 so as to penetrate the
sidewall of the furnace opening unit 209. By adjusting the amount
of power supplied to the heater 207 based on temperature
information detected by the temperature sensor 263, the inner
temperature of the process chamber 201 becomes a predetermined
temperature. The temperature sensor 263 is installed along the
inner wall of the process tube 203, like the first to third nozzles
233a, 233b and 233e.
[0031] In the first embodiment described herein, a gas as supply
unit 232a for supplying a raw material gas and an inert gas is
connected to the first nozzle 233a, and a gas supply unit 232b for
supplying a reactive gas and an inert gas is connected to the
second nozzle 233b. That is, in the first embodiment described
herein, the raw material gas and the reactive gas are supplied
through the separate nozzles. A cleaning gas supply unit 232e for
supplying a cleaning gas is connected to the third nozzle 233e.
[0032] Inert gas supply units 232c and 232d for supplying an inert
gas such as N.sub.2 gas (nitrogen) are connected to the furnace
opening unit 209.
[0033] A seal cap 219 capable of airtightly closing the opening of
the lower end of the furnace opening unit 209 is installed at the
lower portion of the furnace opening unit 209. The seal cap 219 is
in contact with the lower end of the furnace opening unit 209 from
thereunder. The seal cap 219 is formed of a metal such as stainless
steal and is disk-shaped. An O-ring 220b serving as a seal member
which is in contact with the lower end of the furnace opening unit
209 is installed on the upper surface of the seal cap 219. A
rotating mechanism 267 for rotating the boat 217 described later is
installed at the opposite surface of the surface of the seal cap
219, which is in contact with the process chamber 201. The rotating
mechanism 267 has a rotating shaft 255 penetrating the seal cap 219
and connected to the boat 217. As the rotating mechanism 267
rotates the boat 217, the wafer 200 is rotated. The boat 217 and
the seal cap 219 are vertically lifted/lowered by a boat elevator
215 serving as an elevating mechanism disposed outside the process
tube 203. In this way, the boat 217 may be loaded into the process
chamber 201 or unloaded out of the process chamber 201.
[0034] The boat 217 is formed of a material such as quartz
(SiO.sub.2) and silicon carbide (SiC).
[0035] An insulating member 218 formed of a heat-resisting material
such as quartz (SiO.sub.2) and silicon carbide (SiC) is installed
under the boat 217. The insulating member 218 suppresses heat from
transmitting to the seal cap 219 from the heater 207.
[0036] As illustrated in FIG. 2, the furnace opening unit 209 is
formed of a metal such as stainless steal (SUS) and nickel (Ni)
alloy, and cylindrical with an open upper end and an open lower
end. The furnace opening unit 209 has an upper surface 209a, an
inner circumferential surface 209b and a lower surface 209c (refer
to FIG. 4). The inner circumferential surface 209b has a plurality
of ports in which the gas supply units 232a and 232b, the inert gas
supply units 232c and 232d, the cleaning gas supply unit 232e and
the temperature sensor 263 are respectively mounted. In the first
embodiment described herein, ports 319a, 319b, 319c, 319d, 319e and
319f are installed.
[0037] The gas supply units 232a and 232b are mounted in the ports
319a and 319b, respectively. The inert gas supply units 232c and
232d for supplying an inert gas such as N.sub.2 gas are mounted in
the ports 319c and 319d, respectively. The cleaning gas supply unit
232e is mounted in the port 319e. The temperature sensor 263 is
installed in the port 310f.
[0038] Concave portions and convex portions are concentrically
formed on the upper surface 209a of the furnace opening unit 209.
Specifically, a convex portion 209a-1, a concave portion 209a-2
serving as a buffer trench, a convex portion 209a-3, a concave
portion 209a-4 and a convex portion 209a-5 are sequentially formed
from the inner circumference toward the outer circumference of the
upper surface 209a. A plurality of furnace opening trenches 209d
serving as communication paths connecting the concave portion
209a-2 to the inner circumferential surface 209b are formed in the
convex portion 209a-1. In the first embodiment described herein,
the furnace opening trench 209d is a groove or notch. The plurality
of furnace opening trenches 209d may be holes penetrating the
convex portion 209a-1. Holes 209e and 209e communicating with the
ports 319c and 319d, respectively, are disposed at the concave
portion 209a-2 above the ports 319c and 319d. An inert gas supplied
through the inert gas supply units 232c and 232d is supplied to the
concave portion 209a-2 through the ports 319c and 319d mounted in
the inert gas supply units 232c and 232d and the holes 209e and
209e communicating with the ports 319c and 319d, respectively. The
concave portion 209a-2 serving as a buffer trench functions as a
gap 322 (refer to FIG. 4 described later) which is a flow path
through which an inert gas flows.
[0039] The furnace opening trenches 209d are arranged at intervals
depending on the distance from the hole 209e. Desirably, the
arrangement intervals between the respective furnace opening
trenches 209d may be reduced as the furnace opening trenches 209d
are away from the hole 209e. The furnace opening trench 209d close
to the hole 209e supplies a relatively large amount of inert gas to
the inner circumferential surface of the furnace opening unit 209,
and the furnace opening trench 209d away from the hole 209e
supplies a relatively small amount of inert gas to the inner
circumferential surface of the furnace opening unit 209. This is
because, since the inert gas supplied from the hole 209e is
supplied to the inner circumferential surface of the furnace
opening unit 209 through the plurality of furnace opening, trenches
209d while flowing through the concave portion 209a-2 (gap 322),
the flow rate of the inert gas decreases until the inert gas
reaches the furnace opening trench 209d away from the hole 209e. By
reducing the arrangement intervals between the respective furnace
opening trenches 209d as the furnace opening trenches 209d are away
from the hole 209e, a sufficient flow rate of inert gas can be
supplied to the furnace opening trench 209d away from the hole
209e, and the amounts of inert gas supplied to the inner
circumferential surface of the furnace opening unit 209 from the
respective furnace opening trenches 209d can be uniformized.
[0040] Depending on conditions such as the temperature distribution
of the furnace opening unit 209 and the arrangement relation
between the gas supply units, a region to which by-products easily
adhere is formed on the surface of the furnace opening unit 209, or
a region to which by-products hardly adhere is formed on the
surface of the furnace opening unit 209. In this case, the
arrangement intervals between the respective furnace opening
trenches 209d may be properly adjusted to increase or decrease the
amount of inert gas supplied through each of the furnace opening
trenches 209d. For example, the arrangement intervals between the
respective furnace opening trenches 209d may be increased for the
region where by-products hardly adhere, and decreased for the
region where by-products easily adhere.
[0041] The amount of inert, gas supplied through each of the
furnace opening trenches 209d may also be adjusted by changing the
size of the furnace opening trench. For example, the opening area
of the furnace opening trench 209d close to the hole 209e may be
decreased, and the opening area of the furnace opening trench 209d
away from the hole 209e may be increased.
[0042] As illustrated in FIG. 3, a furnace opening cover 320
serving as a cover member for covering the inner circumferential
surface 209b of the furnace opening unit is mounted on the furnace
opening unit 209. The furnace opening cover 320 is formed of a
heat-resisting material such as quartz (SiO.sub.2). The furnace
opening cover 320 covers the convex portion 209a-1 and the concave
portion 209a-2 of the upper surface of the furnace opening unit 209
constituting the process chamber 201 and the entirety of the inner
circumferential surface 209b. That is the cross-sectional surface
of the furnace opening cover 320 has an L-shaped structure that
includes a side portion running along the inner circumferential
surface 209b and a horizontal portion extending in a horizontal
direction from the upper end of the side portion.
[0043] Notches 323 for mounting the temperature sensor 263 and the
nozzles 233a, 333b and 233e as the gas introduction units in the
ports 319 are disposed at the inner circumferential surface of the
furnace opening cover 320. Furnace opening cover trenches 320a are
disposed at the outer circumference of the upper surface of the
furnace opening cover 320. In the first embodiment described
herein, each of the furnace opening cover trenches 320a is a groove
or notch. The furnace opening cover trenches 320a may be holes
penetrating the upper surface of the furnace opening cover 320.
Through the gap 322 and the furnace opening cover trenches 320a, an
inert gas may be supplied to above the furnace opening cover 320,
thereby preventing by-products from adhering to the contact surface
between the furnace opening unit 209 and the process tube 203.
[0044] The intervals between the respective furnace opening cover
trenches 320a may be decreased as the furnace opening cover
trenches 320a are away from the bole 209e. Such a structure can
prevent the decrease in amount of supplied inert gas as the furnace
opening cover trenches 320a are away from the inert gas supply
units 232c and 232d. Thus, an inert gas (purge gas) can be
uniformly supplied onto the inner circumferential surface of the
furnace opening cover 320.
[0045] As illustrated in FIG. 5, the gap 322 serving as a flow path
for passing an inert gas is disposed between the furnace opening
cover 320 and the concave portion 209a-2 of the upper surface of
the furnace opening unit 209, with the furnace opening cover 320
mounted on the furnace opening unit 209. A gap 324 serving as a
flow path for passing an inert gas is disposed between the inner
circumferential surface 209b of the furnace opening unit 209 and
the furnace opening cover 320. A gap 325 serving as a flow path for
passing an inert gas is disposed under the furnace opening cover
320.
[0046] That is, the inert as such as N.sub.2 gas is supplied into
the gap 322 through the hole 209e and the inert gas supply units
232c and 232d connected to the ports 319c and 319d, and supplied
into the gap 324 and the gap 325 through the furnace opening trench
209d, the gap 324 being disposed along the entirety of the inner
circumferential surface of the furnace opening unit 209 and
corresponding to the space between the furnace opening unit 209 and
the furnace opening cover 320. Thus, the upper surface and the
inner circumferential surface of the furnace opening unit 209 are
purged.
[0047] The first embodiment described herein exemplifies the gap
322 formed at the upper surface of the furnace opening unit 209.
However, the first embodiment is not limited thereto. In the first
embodiment described herein, a gap communicating, with the inner
circumferential surface 209b of the furnace opening unit 209 may be
formed at a surface of the furnace opening cover 320, facing the
upper surface of the furnace opening unit 209. Thus, the inert gas
can be uniformly supplied between the furnace opening unit 209 and
the furnace opening cover 320, thereby more efficiently suppressing
the occurrence of particles.
[0048] The first embodiment described herein exemplifies that the
inert was supply units 232c and 232d are connected to the ports
319c and 319d, and the inert gas (purge gas) is supplied between
the inner circumferential surface of the furnace opening unit 209
and the furnace opening cover 320. However, the cleaning gas supply
unit 232e for supplying a cleaning gas such as hydrogen fluoride
(HF) may be connected to the third and fourth ports 319c and 319d.
The supply of the cleaning gas between the inner circumferential
surface of the furnace opening unit 209 and the furnace opening
cover 320 can remove by-products, and prevent the occurrence of
particles,
[0049] A controller 280 serving as a control unit controls the APC
valve 243, the heater 207, the temperature sensor 263, the vacuum
pump 246, the rotating mechanism 267 and the boat elevator 215.
[0050] Next, a substrate processing process according to the first
embodiment described herein will be described with reference to
FIGS. 1 and 6. The substrate processing process according to the
first embodiment described herein includes a SiO film forming step
S100 for forming a SiO film on a wafer 200 and a cleaning step S200
for removing deposits adhering to a portion such as the inner wall
of the process chamber 201. In the following descriptions, the
respective units constituting the substrate processing apparatus
are controlled by the controller 280.
[0051] While at least the wafer 200 is processed during the
substrate processing process according to the first embodiment
described herein, an inert gas is supplied through the gas supply
units 232a and 232b and the inert gas supply units 232c and 232d
which are installed at the lower end of the process tube 203. In
the substrate processing process according to the first embodiment
described herein, the inert gas may be supplied at all times.
Desirably, however, when a metallic member such as the rotating
shaft 255 of which a part is exposed in the process chamber 201 is
likely to corrode, for example, a corrosive gas is supplied into
the process chamber 201 or remains in the process chamber 201, the
inert gas may be supplied.
SiO Film Forming Step S100
[0052] At the SiO film forming step S100, steps S104 and S106 are
repeated to form a SiO film on the wafer 200. The step S104
includes forming a silicon-containing layer on the wafer 200 by
supplying hexachloro-disilane (Si.sub.2Cl.sub.6, abbreviated to
HCDS) gas as a raw material gas onto the wafer 200, and the step
S104 includes oxidizing the silicon-containing layer by supplying
O.sub.2 gas under a pressure less than the atmospheric pressure.
Hereafter, the SiO film forming step S100 will be described in
detail.
Step S101 and step S102
[0053] After the boat 217 is charged with the wafers 200 at step
S101 (wafer charging), the opening of the lower end of the furnace
opening unit 209 is opened. As illustrated in FIG. 1, the boat 217
supporting the wafers 200 is lifted by the boat elevator 215 and
loaded into the process chamber 201 at step S102 (boat loading).
With the boat 217 loaded in the process chamber 201, the seal cap
219 seals the lower end of the furnace opening unit 209 with the
O-ring 220b interposed therebetween.
Step S103
[0054] The inner pressure of the process chamber 201 is adjusted to
a desired degree of vacuum by the pressure sensor 245, the APC
valve 243 and the vacuum pump 246. While the process chamber 201 is
heated by the heater 207, the inner temperature of the process
chamber 201 is adjusted to a desired temperature by the temperature
sensor 263. Then, four film forming steps S104 through S107
described later are sequentially performed.
Step S104
[0055] With the vacuum pump 246 operated, a raw material gas, for
example, HCDS as is supplied through the first nozzle 233a. The
flow rate of HCDS gas is adjusted by an MFC (Mass Flow Controller)
(not illustrated). The HCDS gas of which the flow rate is adjusted
is supplied into the process chamber 201 through the first nozzle
233a and exhausted through the exhaust pipe 231 (HCDS gas supply).
Simultaneously, an inert gas such as N.sub.2gas is supplied into
the first nozzle 233a. The inert gas is supplied with the HCDS gas
into the process chamber 201, and exhausted through the exhaust
pipe 231.
[0056] Examples of a silicon-containing raw material gas may
include inorganic raw material gases such as dichlorosilane
(SiH.sub.2Cl.sub.2, abbreviated to DCS) gas, tetrachlorosilane
(SiCl.sub.4, abbreviated to TCS) gas and monosilane (SiH.sub.4) gas
and organic raw material gases such as amino-silane-based
tetrakis(dimethylamino)silane (Si(N(CH.sub.3).sub.2).sub.4,
abbreviated to 4DMAS) gas, tris(dimethylamino)silane
(Si(N(CH.sub.3).sub.2).sub.3H, abbreviated to 3DMAS) gas,
bis(diethylamino)silane (Si(N(C.sub.2H.sub.5).sub.2).sub.2H.sub.2,
abbreviated to 2DEAS) gas and bis(tertiary-butyl-amino)silane
(SiH.sub.2(NH(C.sub.4H.sub.9)).sub.2, abbreviated to BTBAS), in
addition to the HCDS gas. In addition to N.sub.2 gas, rare gases
such as Ar gas, He gas, Ne gas and Xe gas may be used as the inert
gas.
Step S105
[0057] After the silicon-containing layer is formed on a portion
such as the surface of the wafer 200, the supply of HCDS gas is
stopped. At this time, by vacuum-exhausting the inner atmosphere of
the process chamber 201 through the vacuum pump 246 with the APC
valve 243 of the exhaust pipe 231 open, the HCDS gas remaining in
the process chamber 201 is removed from the process chamber 201. At
this time, when an inert gas is supplied into the process chamber
201, the remaining HCDS gas can be more efficiently removed
(purge).
Step S106
[0058] After the process chamber 201 is purged, an
oxygen-containing gas such as O.sub.2 gas and an inert gas such as
N.sub.2 gas are supplied through the second nozzle 233b. After the
oxygen-containing gas and the inert gas are supplied into the
process chamber 201 through the second gas supply hole 248b, the
oxygen-containing gas and the inert gas are exhausted through the
exhaust pipe 231.
[0059] In addition to O.sub.2 gas, a gas such as ozone (O.sub.3)
gas may be used as the oxygen-containing gas.
Step S107
[0060] After a silicon-containing layer is modified into a silicon
oxide layer, the supply of the oxygen-containing gas is stopped. At
this time, by vacuum-exhausting the process chamber 20 through the
vacuum pump 246 with the APC valve 243 of the exhaust pipe 231
open, the oxygen-containing gas remaining in the process chamber
201 is removed from the process chamber 201. At this time, when an
inert gas is supplied into the process chamber 201, the remaining
oxygen-containing gas can be more efficiently removed.
Step S108
[0061] The cycle in which the above-described steps S104 through
S107 are sequentially performed is performed a predetermined number
of times. Thus, a predetermined thickness of SiO film may be formed
on the wafer 200, the surface of the boat 217, and a member in the
process chamber 201 such as the inner wall of the process chamber
201.
Step S109 and step S110
[0062] After the predetermined thickness of SiO film is funned, an
inert gas is supplied into the process chamber 201 from the first
and second nozzles 233a and 233b, and exhausted through the exhaust
pipe 231. The inert gas serves as a purge gas. The inside of the
process chamber 201 is purged by the inert gas, and the gas
remaining in the process chamber 201 is removed from the process
chamber 201 (purge). Then, the inner atmosphere of the process
chamber 201 is replaced with the inert gas, and the inner pressure
of the process chamber 201 is returned to normal pressure
(atmospheric pressure return).
Step S111 and step S112
[0063] As the seal cap 219 is lowered by the boat elevator 215, the
lower end of the furnace opening unit 209 is opened. The processed
wafer 200 is unloaded from the lower end of the furnace opening
unit 209 to the outside of the reaction tube 203, with the wafer
200 supported by the boat 217 (boat unloading). After the boat is
unloaded, the lower end opening of the furnace opening unit 209 is
sealed by a shutter (not illustrated) with an O-ring 220c
interposed therebetween (shutter closing). Then, the processed
wafer 200 is discharged from the boat 217 (wafer discharging).
[0064] Next, the cleaning step S200 of the process furnace 202
according to the first embodiment described here will be
described.
Cleaning step S200
[0065] When the SiO film forming step S100 is repeated, the SiO
film is accumulated on members in the process chamber 201. That is,
deposits including SiO are adhered to and accumulated on the
portion such as the inner wall of the process tube 203. When the
thickness of the deposits adhered to and accumulated on the portion
such as the inner wall reaches a predetermined thickness of 1 .mu.m
to 5 .mu.m, for example, before the deposits are peeled off or
fall, the inside of the process tube 203 is cleaned. When the
inside of the process tube 203 is cleaned, the deposits accumulated
in the process chamber 201 are removed by supplying HF gas as the
cleaning gas into the process chamber 201 heated to a predetermined
temperature or supplying HF gas diluted by the inert gas into the
process chamber 201. Hereafter, the cleaning step S200 will be
described in detail.
Step S201
[0066] After the processed wafer 200 is discharged from the boat
217, the empty boat 217 is lifted by the boat elevator 215 and
loaded into the process chamber 201 (boat loading). In this state,
the seal cap 219 seals the lower end of the furnace opening unit
209 with the O-ring 220b interposed therebetween.
Step S202
[0067] The process chamber 201 is vacuum-exhausted by the vacuum
pump 246 such that the inner pressure of the process chamber 201
becomes a desired degree of vacuum. At this time, the inner
pressure of the process chamber 201 is measured through the
pressure sensor 245, and the APC valve 243 is feedback-controlled
based on the measured pressure information (pressure control). The
process chamber 201 is heated by the heater 207 until the inner
temperature of the process chamber 201 reaches a desired
temperature. At this time, until the inner temperature of the
process chamber 201 reaches the desired temperature (cleaning
temperature), power supplied to the heater 207 is
feedback-controlled based on temperature information detected by
the temperature sensor 263 (temperature control).
Step S203
[0068] Then, HF gas is supplied as a cleaning gas into the third
nozzle 233e in a state where the inner temperature and pressure of
the process chamber 201 are maintained at a predetermined
temperature and pressure (HF gas supply). The HF gas is supplied
into portions such as the boat 217 and the inner will of the
process chamber 201 through the third nozzle 233e, and exhausted
through the exhaust pipe 231.
[0069] When the HF gas introduced into the process chamber 201 or
diluted HF gas is passed through the inside of the process chamber
201, the HF gas comes in contact with the deposits including a thin
film such as SiO, which are accumulated on the inner wall of the
process chamber 201 or the surface of the boat 217. At this time,
the deposits are removed by a thermo-chemical reaction. That is the
deposits are removed by an etching reaction between the deposits
and active species generated by thermal decomposition of the HF
gas.
Step S204
[0070] When the cleaning of the process chamber 201 is end after a
preset deposit etching time has elapsed, the supply of HF gas or
diluted HF gas into the process chamber 201 is stopped. Then, by
supplying an inert gas such as N.sub.2 gas into the process chamber
201 and exhausting the supplying inert gas through the exhaust pipe
231, the inside of the process chamber 201 is purged.
[0071] In addition to HF gas, fluorine-containing gases such as
chlorine trifluoride (ClF.sub.3) gas, nitrogen trifluoride
(NF.sub.3) gas and fluorine (F.sub.2) gas ma be used as the
cleaning gas.
Step S205
[0072] When the inside of the process chamber 201 is purged by the
inert gas such that the gas remaining in the process chamber 201 is
removed from the process chamber 201, the inner atmosphere of the
process chamber 201 is replaced with the inert gas, and the inner
pressure of the process chamber 201 is returned to normal pressure
(atmospheric pressure return).
Step S206
[0073] Then, as the seal cap 219 is lowered by the boat elevator
215, the lower end of the furnace opening unit 209 is opened. The
empty boat 217 is unloaded to the outside of the process tube 203
through the lower end of the furnace opening unit 209 (boat
unloading).
[0074] As illustrated in FIG. 7, an inert gas is supplied into the
gap 322 of the upper surface of the furnace opening unit 209
through the inert gas supply units 232c and 232d connected to the
ports 319c and 319d, respectively, and supplied to the gaps 324 and
325 formed along the entirety of the inner circumferential surface
of the furnace opening unit 209 through the furnace opening trench
209d, thereby purging the upper surface and inner circumferential
surface of the furnace opening unit 209. Then, since the inert gas
covers the surface of the furnace opening unit 209, the contact
area between a process gas and the upper surface and inner
circumferential surface of the furnace opening unit 209 is reduced.
Therefore, although a corrosive gas is used as the process gas, the
occurrence of particles can be suppressed while the corrosion of
the furnace opening unit is suppressed. As the inert gas is
supplied between the inner circumferential surface 209b of the
furnace opening unit 209 and the furnace opening cover 320 through
the gap 322, the inert gas flows downward in the gap 324 between
the furnace opening unit 209 and the furnace opening cover 320
(down flow). Thus, although by-products adhering to the gaps 322
and 324 are peeled off, the by-products can be prevented from
scattering as particles in the wafer region.
[0075] In order to increase the purge effect of the furnace opening
unit in the first embodiment described herein, the clearance
between the furnace opening unit 209 and the furnace opening cover
320 may be set to a small value of not more than 2 mm, for example,
as illustrated in FIG. 7. When the clearance between the furnace
opening unit 209 and the furnace opening cover 320 is narrow, it is
possible to efficiently prevent by-products from adhering to the
inner circumferential surface of the furnace opening unit 209. The
by-products adhering to the inner circumferential surface of the
furnace opening unit 209 can be removed by supplying an inert gas
through the ports 319c and 319d. The cleaning gas supply unit may
be connected to the ports 319c and 319d and supply a cleaning gas
through the ports 319c and 319d.
[0076] Next, a substrate processing apparatus according to a second
embodiment described herein will be described with reference to
FIG. 8. In the second embodiment illustrated in FIG. 8, the ports
319c and 319d connected to the respective inert gas supply units
232c and 232d are formed through the sidewall of the furnace
opening unit 209. Thus, an inert gas is directly supplied to the
gap 324 formed between the inner circumferential surface of the
furnace opening, unit 209 and the furnace opening, cover 320,
without passing through the gap 322.
[0077] Although the clearance between the inner circumferential
surface of the furnace opening unit 209 and the furnace opening
cover 320 is wide as illustrated in FIG. 8, a flow path of inert
gas can be formed to prevent the corrosion of the furnace opening
unit, thereby suppressing the occurrence of particles. Although a
cleaning gas is used instead of the inert gas, the cleaning
efficiency can be improved, and the maintenance time can be
shortened. In second embodiment described herein, a flow path of
inert gas can be formed even when the furnace opening unit having a
complex shape is used.
[0078] As the furnace opening cover 320 is installed to cover the
upper surface and inner circumferential surface of the furnace
opening unit 209 and the inert gas and the cleaning gas are
supplied between the furnace opening unit 209 and the furnace
opening cover 320, the inert gas and the cleaning gas are supplied
onto the inner surface of the process chamber 201 of the furnace
opening unit 209, thereby preventing corrosion or adhesion of
by-products to the furnace opening unit 209.
[0079] Next, the second embodiment described herein will be
described in detail. In the second embodiment, the descriptions of
the same components as those of the first embodiment are omitted
herein.
[0080] FIG. 9 is a plan view of a furnace opening unit 409
according to the second embodiment described herein.
[0081] The second embodiment is different from the first embodiment
in that a furnace opening cover 520 according to the second
embodiment is divided into a plurality of furnace opening cover
members with an annular sector shape. A plurality of projections
410 for installing the furnace opening cover 520 protruding inward
are installed at the inner circumferential surface 409b of the
furnace opening unit 409. The plurality of projections 410 are
arranged at unequal intervals therebetween.
[0082] As illustrated in FIG. 10, the furnace opening cover
includes a plurality of large and small furnace opening cover
members which are divided along the circumferential direction.
Referring to FIG. 10, the plurality of large and mall furnace
opening cover members cover the furnace opening unit 409 except
locations at which the nozzles 233a, 233b and 233e or nozzle
supports 521 for supporting the nozzles 233a, 233b and 233e are
installed, thereby protecting the furnace opening unit 409. The
furnace opening cover includes four furnace opening cover members
520-1 through 520-4, for example. The four furnace opening cover
members 520-1 through 520-4 are mounted on the furnace opening unit
409. By mounting the plurality of furnace opening cover members on
the furnace opening unit 409, the corrosion of the furnace opening
unit 409 can be prevented.
[0083] The four furnace opening cover members 520-1 through 520-4
have different sizes, but include common components. In the second
embodiment, the furnace opening cover member 520-1 among the
plurality of furnace opening cover members will be representatively
described with reference to FIGS. 11A and 11B.
[0084] The furnace opening cover member 520-1 has an annular sector
shape, and includes an upper portion 520a protruding in the
horizontal direction at the inner circumference and a side surface
portion 520b extending in substantially the vertical direction from
the outer circumference of the upper portion 520a and facing the
inner circumferential surface 409b of the furnace opening unit 409.
The furnace opening cover member 520-1 includes openings 522 formed
at the side surface portion 520b so as to install the furnace
opening cover member 520-1 onto the L-shaped projections 410 of the
furnace opening unit 409. The furnace opening cover member 520-1
may include two openings, for example. A protrusion 524 protruding
outward [toward the furnace opening unit 409] is installed between
the two openings 522 and 522. As the two openings 522 are hooked to
the respective projections 410, the furnace opening cover member
520-1 is coupled to the furnace opening unit 409. The upper surface
of the furnace opening cover member 520-1 is positioned at a higher
level than at least the concave portion 409a-2 of the upper surface
of the furnace opening unit 409. More desirably, the upper surface
of the furnace opening; cover member 520-1 is positioned at a level
equal to or higher than the upper surface of the convex portion
409a-1.
[0085] The furnace opening cover members 520-1 through 520-4 cover
the entirety of the inner circumferential surface 409b of the
furnace opening unit 409 constituting the process chamber 201. As
the openings 522 are hooked to the projections 410 of the furnace
opening unit 409 and the protrusions 524 are in contact with the
inner circumferential surface of the furnace opening: unit 409, the
furnace opening, cover members 520-1 through 520-4 are mounted on
the furnace opening unit 409. Thus, a clearance between the furnace
opening cover 520 and the inner circumferential surface of the
furnace opening unit 409 is secured to form a gap serving as a flow
path through which an inert gas flows. Furthermore, the furnace
opening cover 520 is prevented from swaying with respect to the
furnace opening unit 409. As the furnace opening cover 520 is
hooked to the furnace opening unit 409, the furnace opening cover
520 can be simply exchanged even though the furnace opening unit
409 is not detached.
[0086] The L-shaped upper end of the furnace opening cover 520
protruding inward is exemplified in the second embodiment described
herein. However, the second embodiment is not limited to such an
example. For example, the upper end of the furnace opening cover
520 may additionally protrude outward about 1-2 mm to have a
T-shape. That is, the furnace opening cover 520 may include a side
surface portion running along the inner circumferential surface
409b and an extension portion extending inward and outward in a
horizontal direction from the upper end of the side surface
portion, The projection 410 may not be T-shaped, but cylindrical.
The furnace opening cover 520 may be installed by inserting the
projections 410 into the openings 522.
[0087] As illustrated in FIGS. 12 and 13, the lower surface of the
process tube 203 is mounted on the upper surface 409a of the
furnace opening unit 409. With the process tube 203 mounted on the
furnace opening unit 409, the gap 322 serving as a flow path
through which an inert gas flows is formed between the concave
portion 409a-2 of the upper surface of the furnace opening unit 409
and the lower surface of the process tube 230. The gap 324 serving
as a flow path through which an inert gas flows is formed between
the inner circumferential surface 409b of the furnace opening unit
409 and the outer circumferential surface of the furnace opening
cover 520. The gap 325 serving as a flow path through which an
inert gas flows is formed under the furnace opening cover 520.
[0088] The inert gas such as N.sub.2 gas is supplied onto the lower
surface of the process tube 203 along the circumferential direction
through the inert gas supply units 232c and 232d connected to the
ports 319c and 319d, the gap 322 and the hole 409e, and supplied
into the gap 324 and the gap 325 through a furnace opening trench
409d, the gap 324 formed along the entirety of the inner
circumferential surface of the furnace opening unit 409 and
corresponding to the space between the furnace opening unit 409 and
the furnace opening cover 520. Then, while the upper surface and
inner circumferential surface of the furnace opening unit 409 are
purged, the inert gas covers the surface of the furnace opening
unit. Thus, the contact area between a process gas and the upper
surface and inner circumferential surface of the furnace opening
unit 409 is reduced. Therefore, although a corrosive gas is used as
the process gas, the occurrence of particles can be suppressed
while the corrosion of the furnace opening unit is suppressed. When
an inert gas is supplied to the gaps 324 and 325 through the gap
322 and the furnace opening, trench 409d, the inert gas flows
downward in the gap 324 between the furnace opening unit 409 and
the furnace opening cover 520 (down flow). Such a structure can
prevent particles from penetrating the wafer region or clogging the
inner circumferential surface of the furnace opening cover 320.
[0089] While supplying the inert gas through the port 319c and 319d
are exemplified in the second embodiment described herein, the
second embodiment is not limited thereto. For example, a cleaning
gas such as HF gas may be supplied instead of the inert gas, and a
mixture of the inert gas and the cleaning gas may be supplied.
[0090] The embodiments described above have at least one of the
following effects (1) through (8).
[0091] (1) By installing the furnace opening cover 320 to cover the
upper surface and inner circumferential surface of the furnace
opening unit 209 and supplying an inert gas and a cleaning gas
between the furnace opening unit 209 and the furnace opening cover
320, the inner surface of the process chamber 201 of the furnace
opening unit 209 can be covered by the inert gas and the cleaning
gas, and the corrosion of the furnace opening unit 209 can be
prevented while by-products are prevented from adhering to the
furnace opening unit 209.
[0092] (2) By reducing the arrangement intervals between the
respective furnace opening trenches 209d as the furnace opening
trenches 209d are away from the hole 209e, the reduction in amount
of supplied inert gas with the furnace opening trenches 209d away
from the hole 209e can be prevented, and the inner surface of the
furnace opening unit 209 can be efficiently purged
(exhausted/replaced).
[0093] (3) By properly adjusting the arrangement intervals between
the respective furnace opening trenches 209d or the opening areas
of the furnace opening trenches 209d, the amount of inert gas
supplied to the inner circumferential surface of the furnace
opening unit 209 can be adjusted, and the inner circumferential
surface of the furnace opening unit 209 can be purged more
efficiently.
[0094] (4) By forming the plurality of furnace opening cover
trenches 320a at the outer circumference of the upper surface of
the furnace opening cover 320, an inert as can be supplied to above
the furnace opening cover 320 from the gap 322. Thus, by-products
can be prevented from adhering to the contact surface between the
furnace opening; unit 209 and the process tube 203, The intervals
between the respective furnace opening cover trenches 320a may be
reduced depending on the distance from the hole 209e. Such a
structure can prevent the decrease in amount of supplied inert gas
with the furnace opening cover trenches 320a away from the inert
gas supply units 232c and 232d. Thus, the inert gas (purge gas) can
be uniformly supplied onto the inner circumferential surface of the
furnace opening cover 320. The exhaust pipe 231 may be installed
above the furnace opening cover trench 320a. Thus, the inert gas
can be supplied more uniformly and efficiently.
[0095] (5) By supplying an inert gas between the inner
circumferential surface 209b of the furnace opening unit 209 and
the furnace opening cover 320 through the gap 322, the inert gas
flows downward in the gap 324 between the furnace opening unit 209
and the furnace opening cover 320 (down flow). Thus, although
by-products adhering to the gaps 322 and 324 are peeled of the
by-products can be prevented from scattering as particles in the
wafer region.
[0096] (6) As the furnace opening cover 520 is constituted by the
plurality of furnace opening cover members 520-1 through 520-4, the
plurality of furnace opening cover members 520-1 through 520-4
almost cover the inner circumferential surface 409b of the furnace
opening unit 409, the openings 522 are hooked to the projections
410 of the furnace opening unit 409, and the protrusions 524 are
mounted to be in contact with the inner circumferential surface of
the furnace opening unit 409, the furnace opening cover 520 can
secure a clearance from the inner circumferential surface of the
furnace opening unit 409. Thus, a gap through which an inert gas
flows can be formed to suppress the furnace opening cover 520 from
swaying with respect to the furnace opening unit 409.
[0097] (7) As the L-shaped furnace opening cover 520 protruding in
the horizontal direction is hooked to the furnace opening unit 409,
the furnace opening cover 520 can be simply exchanged even though
the furnace opening unit 409 is not detached.
[0098] (8) As the upper surface of the furnace opening cover 520
installed on the furnace opening unit 409 is set at a higher level
than the furnace opening trench 409d, an inert gas supplied through
the furnace opening trench 409d can be efficiently supplied to the
gap 324 without leaking to the process furnace.
[0099] The substrate can be prevented from being contaminated in
the substrate processing apparatus, and the maintenance cycle can
be extended to thereby raise the manufacturing efficiency.
[0100] In the embodiments described herein, forming the gap 322 at
the upper surface of the furnace opening unit 209 has been
exemplified. However, the technique described herein is not limited
thereto. For example, a gap can be formed at a surface of the
furnace opening cover 320 facing the upper surface of the furnace
opening unit 209, and connected to the inner circumferential
surface 209b of the furnace opening unit 209. Such a structure can
uniformly supply an inert gas or cleaning gas between the furnace
opening unit 209 and the furnace opening cover 320, thereby more
efficiently suppressing the occurrence of particles.
[0101] The technique described herein is not limited to the
above-described embodiments. For example, a single tube serving as
the process tube has been exemplified in the embodiments. However,
the embodiments are not limited thereto, but a double tube
including outer and inner tubes or a triple tube may be
applied.
[0102] In the embodiments described herein, two inert gas supply
units are installed under the process tube 203. However, the
embodiments are not limited thereto. For example, only a single
inert gas supply unit may be installed. When one inert gas supply
unit is installed, the inert gas supply unit is installed at a side
facing the exhaust pipe 231. Thus, a smooth flow path can be formed
in the entire gas supply and exhaust structure.
[0103] The technique described herein can be applied to a
semiconductor manufacturing technique, or particularly a heat
treatment technique for performing a process in a state where a
substrate is housed in a process chamber and heated by a heater.
The technique described herein can be applied to a substrate
processing apparatus which is used for performing various processes
on a semiconductor wafer for manufacturing a semiconductor
integrated circuit device (semiconductor device), the various
processes including an oxidation process, a diffusion process,
reflow or annealing process for activating or flattening a carrier
after ion implantation, and a film forming process through thermal
CVD reaction.
Preferred Embodiments
[0104] Hereinafter, preferred embodiments described herein are
supplementarily noted.
Supplementary Note 1
[0105] According to an embodiment, a method for manufacturing a
semiconductor device includes: a substrate housing step of housing
a substrate into a reaction tube having a furnace opening unit
installed thereunder, the furnace opening unit having a trench and
communication path formed at an upper surface thereof the
communication path connecting the trench to an inner
circumferential surface of the furnace opening unit; and a
substrate processing step of processing the substrate by supplying
a process gas onto the substrate housed in the reaction tube
through a process gas supply unit. At the substrate processing
step, an inert gas is supplied into a space between a furnace
opening, cover and the furnace opening unit through an inert as
supply unit connected to the furnace opening unit, the furnace
opening cover covering the trench, the communication path, and at
least the inner circumferential surface of the furnace opening
unit.
[0106] According to the technique described herein, it is possible
to suppress the occurrence of particles.
* * * * *