U.S. patent application number 11/271900 was filed with the patent office on 2006-03-23 for substrate processing apparatus.
Invention is credited to Toru Kagaya, Kazuyuki Okuda, Masanori Sakai.
Application Number | 20060060142 11/271900 |
Document ID | / |
Family ID | 29585950 |
Filed Date | 2006-03-23 |
United States Patent
Application |
20060060142 |
Kind Code |
A1 |
Okuda; Kazuyuki ; et
al. |
March 23, 2006 |
Substrate processing apparatus
Abstract
A substrate processing apparatus includes: a reaction tube; a
gas introducing tube which is in communication with said reaction
tube; a gas exhausting tube having a closing member, and a
controller which controls an opening of the closing member to
substantially stop exhaustion through the exhausting tube from a
predetermined point of time before cleaning gas is supplied from
said gas introducing tube into the reaction tube to a point of time
when several seconds are elapsed after starting of supply of the
cleaning gas into the reaction tube such that there exists a state
in which exhaustion from the gas exhausting tube is stopped while
the cleaning gas is supplied from the gas introducing tube into the
reaction tube to fill the reaction tube with the cleaning gas under
control of the controller.
Inventors: |
Okuda; Kazuyuki; (Tokyo,
JP) ; Kagaya; Toru; (Tokyo, JP) ; Sakai;
Masanori; (Tokyo, JP) |
Correspondence
Address: |
BIRCH STEWART KOLASCH & BIRCH
PO BOX 747
FALLS CHURCH
VA
22040-0747
US
|
Family ID: |
29585950 |
Appl. No.: |
11/271900 |
Filed: |
November 14, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10400577 |
Mar 28, 2003 |
|
|
|
11271900 |
Nov 14, 2005 |
|
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Current U.S.
Class: |
118/715 ;
156/345.24; 156/345.29 |
Current CPC
Class: |
B08B 5/00 20130101; H01L
21/02057 20130101; C23C 16/4412 20130101; C23C 16/4405 20130101;
H01L 21/67253 20130101 |
Class at
Publication: |
118/715 ;
156/345.29; 156/345.24 |
International
Class: |
H01L 21/306 20060101
H01L021/306; C23C 16/00 20060101 C23C016/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 28, 2002 |
JP |
2002-092733 |
Dec 18, 2002 |
JP |
2002-366250 |
Claims
1. A substrate processing apparatus, comprising: a reaction tube; a
gas introducing tube which is in communication with said reaction
tube; a gas exhausting tube having a closing member, and a
controller which controls an opening of said closing member to
substantially stop exhaustion through said exhausting tube from a
predetermined point of time before cleaning gas is supplied from
said gas introducing tube into said reaction tube to a point of
time when several seconds are elapsed after starting of supply of
the cleaning gas into said reaction tube such that there exists a
state in which exhaustion from said gas exhausting tube is stopped
while the cleaning gas is supplied from said gas introducing tube
into said reaction tube to fill said reaction tube with the
cleaning gas under control of said controller.
2. A substrate processing apparatus as recited in claim 1, wherein
said controller controls said opening of said closing member to
substantially stop exhaustion through said exhausting tube from
said predetermined point of time before the cleaning gas is
supplied from said gas introducing tube into said reaction tube to
a point of time when seven seconds are elapsed after the starting
of the supply of the cleaning gas into said reaction tube.
3. A substrate processing apparatus as recited in claim 1, wherein
the exhaustion from said gas exhausting tube is substantially
stopped simultaneously with or before the starting of the supply of
the cleaning gas from said gas introducing tube.
4. A substrate processing apparatus as recited in claim 1, wherein
the exhaustion from said gas exhausting tube is substantially
stopped within seven seconds after the starting of the supply of
the cleaning gas.
5. A substrate processing apparatus as recited in claim 1, wherein
a first stage which fills said reaction tube with the cleaning gas
under the control of said controller and a second stage which
thereafter exhausts gas from said reaction tube are repeated at
least once.
6. A substrate processing apparatus, comprising: a reaction tube; a
gas introducing tube which is in communication with said reaction
tube; a gas exhausting tube having a closing member, and a
controller which controls an opening of said closing member to
substantially stop exhaustion through said exhausting tube from a
predetermined point of time before cleaning gas is supplied from
said gas introducing tube into said reaction tube to a
predetermined point of time after the cleaning gas is started to be
supplied into said reaction tube such that there exists a state in
which exhaustion from said gas exhausting tube is stopped while the
cleaning gas is supplied from said gas introducing tube into said
reaction tube to repeat a first stage which fills said reaction
tube with the cleaning gas under control of said controller and a
second stage which thereafter exhausts gas from said reaction tube
at least once.
7. A substrate processing apparatus as recited in claim 1, wherein
the supply of the cleaning gas from said gas introducing tube is
effected by supplying, after the cleaning gas is supplied into the
reaction tube with a first flow rate, the cleaning gas into the
reaction tube with a second flow rate which is smaller than the
first flow rate.
8. A substrate processing apparatus as recited in claim 7, wherein
a first time period during which the cleaning gas is supplied into
the reaction tube with the first flow rate is shorter than a second
time period during which the cleaning gas is supplied into the
reaction tube with the second flow rate.
9. A substrate processing apparatus as recited in claim 7, wherein
a degree of pressure rise in the reaction tube for a time period
during which the cleaning gas is supplied into the reaction tube
with the first flow rate is higher than a degree of pressure rise
in the reaction tube for a time period during which the cleaning
gas is supplied into the reaction tube with the second flow
rate.
10. A substrate processing apparatus as recited in claim 1, wherein
after the cleaning gas is supplied into the reaction tube and a
pressure in the reaction tube reaches a predetermined value, the
supply of the cleaning gas is stopped for a predetermined time.
11. A substrate processing apparatus, comprising: a reaction tube;
a gas introducing tube which is in communication with said reaction
tube; a cleaning gas supply member which supplies cleaning gas to
said gas introducing tube, and a controller which controls an
opening of said closing member to substantially stop exhaustion
through said exhausting tube from a predetermined point of time
before cleaning gas is supplied from said gas introducing tube into
said reaction tube to a point of time when several seconds are
elapsed after starting of supply of the cleaning gas into said
reaction tube such that there exists a state in which exhaustion
from said gas exhausting tube is stopped while the cleaning gas is
supplied by said cleaning gas supply member through said gas
introducing tube into said reaction tube.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a Continuation of co-pending application
Ser. No. 10/400,577, filed on Mar. 28, 2003, and for which priority
is claimed under 35 U.S.C. .sctn. 120. Application Ser. No.
10/400,577 claims priority under 35 U.S.C. .sctn. 119(a) on
Application No. 2002-092733 filed in Japan on Mar. 28, 2002 and
Application No. 2002-366250 filed in Japan on Dec. 18, 2002. The
entire contents of each of the above-identified applications are
hereby incorporated by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a substrate processing
apparatus, and more particularly, to a cleaning technique in a
reaction chamber of a substrate processing apparatus which is a
producing apparatus of a semiconductor device used when the
semiconductor device is produced on a substrate such as an Si.
[0004] 2. Description of the Related Art
[0005] In a substrate processing apparatus of this kind, it is
known that cleaning gas is supplied and exhausted to and from the
reaction chamber to clean the chamber (see Japanese Patent
Application Laid-open No. 2002-47571).
[0006] A conventional producing apparatus of a semiconductor device
will be explained with reference to FIG. 7. FIG. 7 is a sectional
view showing a conception of a reaction furnace.
[0007] In a self-cleaning operation aimed at removing reaction
by-product adhering to an inner wall or the like of a reaction tube
1 by desired film-forming processing, a flow rate of etching gas 4
as cleaning gas is controlled to a constant value, and the etching
gas 4 is continuously supplied from a gas introducing tube 2 into
the reaction tube 1 from a plurality of holes 8 through a gas
nozzle 7.
[0008] A desired amount of gas is exhausted from the reaction tube
1 by adjusting an opening of a pressure-adjusting valve 5 connected
to the gas exhausting tube 3, thereby maintaining a pressure in the
reaction tube 1 at a constant value.
[0009] In the conventional apparatus and method, however, there is
a problem that nonuniform etching and etching remainder are
generated.
[0010] It is conceived that this is caused because in the
conventional technique, the etching gas is supplied while the
etching gas is exhausted and thus, the following events occur:
[0011] (a) A "flow" is generated toward the gas exhausting tube 3
from the gas introducing tube 2 because of a shape of the reaction
tube 1 or a relation between a supplying position and an exhausting
position of the gas, most of etching gas is consumed at an upstream
portion of the "flow" and the etching gas is less prone to reach a
downstream portion of the "flow".
[0012] (b) A degree of diffusion of gas is greater in a location in
the reaction tube 1 (i.e., in the vicinity of the gas exhausting
tube) where a pressure is low, but the degree of diffusion of gas
is smaller in a location in the reaction tube (i.e., an upper end
of the reaction tube 1 and the like) where the pressure is high.
Therefore, etching gas is less prone to reach a high pressure
location in the reaction tube 1.
[0013] That is, the "flow" toward the gas exhausting tube 3 from
the gas introducing tube 2 is generated, and the etching gas is
less prone to reach a portion which is not located along the
"flow".
[0014] More concretely, as shown with arrows in FIG. 7, a strong
flow portion 11 along the flow of gas is generated from
substantially a center portion to a portion close to the gas
exhausting tube 3 in the reaction tube 1, and a weak flow portion
12 which opposes the flow of gas is generated in an upper portion
in the reaction tube 1. Therefore, a flow rate of gas and a partial
pressure are not constant in the reaction tube 1.
[0015] In this specification, the term "flow" means intentional
airflow generated from the exhausting operation, and a flow caused
by diffusion of gas is excluded.
SUMMARY OF THE INVENTION
[0016] It is a main object of the present invention to carry out
uniform etching, and by extention to effect uniform cleaning in a
reaction tube in a semiconductor device producing apparatus
(substrate processing apparatus) for carrying out self-cleaning
using etching gas such as NF.sub.3.
[0017] According to a first aspect of the present invention, there
is provided a substrate processing apparatus, comprising: [0018] a
reaction tube; [0019] a gas introducing tube which is in
communication with said reaction tube; [0020] a gas exhausting tube
having a closing member, and [0021] a controller which controls an
opening of the closing member to substantially stop exhaustion
through the exhausting tube from a predetermined point of time
before cleaning gas is supplied from the gas introducing tube into
the reaction tube to a point of time when several seconds are
elapsed after starting of supply of the cleaning gas into the
reaction tube such that there exists a state in which exhaustion
from the gas exhausting tube is stopped while the cleaning gas is
supplied from the gas introducing tube into the reaction tube to
fill the reaction tube with the cleaning gas under control of the
controller.
[0022] According to a second aspect of the present invention, there
is provided a substrate processing apparatus, comprising: [0023] a
reaction tube; [0024] a gas introducing tube which is in
communication with the reaction tube; [0025] a gas exhausting tube
having a closing member, and [0026] a controller which controls an
opening of the closing member to substantially stop exhaustion
through the exhausting tube from a predetermined point of time
before cleaning gas is supplied from the gas introducing tube into
the reaction tube to a predetermined point of time after the clean
gas is started to be supplied into the reaction tube such that
there exists a state in which exhaustion from the gas exhausting
tube is stopped while the cleaning gas is supplied from the gas
introducing tube into said reaction tube to repeat a first stage
which fills the reaction tube with the cleaning gas under control
of the controller and a second stage which thereafter exhausts gas
from the reaction tube at least once.
[0027] According to a third aspect of the present invention, there
is provided a substrate processing apparatus, comprising: [0028] a
reaction tube; [0029] a gas introducing tube which is in
communication with the reaction tube; [0030] a cleaning gas supply
member which supplies cleaning gas to the gas introducing tube, and
[0031] a controller which controls an opening of the closing member
to substantially stop exhaustion through the exhausting tube from a
predetermined point of time before cleaning gas is supplied from
the gas introducing tube into the reaction tube to a point of time
when several seconds are elapsed after starting of supply of the
cleaning gas into said reaction tube such that there exists a state
in which exhaustion from the gas exhausting tube is stopped while
the cleaning gas is supplied by said cleaning gas supply member
through the gas introducing tube into the reaction tube.
BRIEF DESCRIPTION OF THE DRAWINGS
[0032] The above and further objects, features and advantages of
the present invention will become more apparent from the following
detailed description taken in conjunction with the accompanying
drawings, wherein:
[0033] FIG. 1 is a perspective view of a substrate processing
apparatus according to an embodiment of the present invention;
[0034] FIG. 2 is a sectional view showing a reaction furnace used
in a substrate processing apparatus according to an embodiment of
the present invention;
[0035] FIG. 3 is a gas system chart showing a gas system of a
substrate processing apparatus according to an embodiment of the
present invention;
[0036] FIG. 4 is a flowchart showing a processing flow in cleaning
steps of a substrate processing apparatus according to an
embodiment of the present invention;
[0037] FIG. 5 is a time chart of cleaning steps of a substrate
processing apparatus according to an embodiment of the present
invention;
[0038] FIG. 6 is a flowchart showing a processing flow in cleaning
steps of a substrate processing apparatus according to another
embodiment of the present invention; and
[0039] FIG. 7 is a sectional view showing a conventional reaction
furnace.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0040] A substrate processing apparatus according to a first
preferred aspect of the present invention comprises: [0041] a
reaction tube; [0042] a gas introducing tube which is in
communication with the reaction tube; [0043] a gas exhausting tube
having a closing member, and [0044] a controller which controls an
opening of the closing member to substantially stop exhaustion
through the exhausting tube from a predetermined point of time
before cleaning gas is supplied from the gas introducing tube into
the reaction tube to a point of time when several seconds are
elapsed after starting of supply of the cleaning gas into the
reaction tube such that there exists a state in which exhaustion
from the gas exhausting tube is stopped while the cleaning gas is
supplied from said gas introducing tube into the reaction tube to
fill the reaction tube with the cleaning gas under control of the
controller.
[0045] Here, the expression "to substantially stop exhaustion"
includes not only a case in which the exhaustion of gas is
completely stopped but also a case in which exhaustion of slight
exhaust amount is permissible only if cleaning gas is substantially
uniformly diffused in the reaction tube. Therefore, the flow of
cleaning gas in the reaction tube is substantially stopped, the
reaction tube can be filled with cleaning gas by diffusing the
cleaning gas, the partial pressure of etching gas in the reaction
tube becomes uniform, a pressure of the etching gas rises and thus,
the etching speed (cleaning speed) is also increased.
[0046] The exhaustion from the gas exhausting tube may
substantially be stopped simultaneously with or before the start of
supply of the cleaning gas, and the exhaustion from the gas
exhausting tube may substantially be stopped before several seconds
are elapsed after the cleaning gas is supplied. When the exhaustion
is stopped after the start of supply of cleaning gas from the gas
introducing tube, in the timing of stop of the exhaustion, time
required for closing the exhausting tube and time required for
easily diffusing cleaning gas into the reaction tube substantially
entirely are taken into consideration. For example, if time
required for closing the exhausting tube is two seconds and time
required for easily diffusing cleaning gas into the reaction tube
substantially entirely is five second, the total is seven seconds,
and it is preferable that the exhaustion is stopped within the
seven seconds. A reason why a margin of five seconds is required is
that since the exhaustion is stopped after a flow of gas is
produced in the reaction tube, if a distance between a supply port
of gas and an exhaust port is long and the path is complicated, it
is possible to allow the cleaning gas to reach the reaction tube
quickly.
[0047] A substrate processing apparatus according to a second
preferred aspect of the present invention comprises: [0048] a
reaction tube; [0049] a gas introducing tube which is in
communication with the reaction tube; [0050] a gas exhausting tube
having a closing member, and [0051] a controller which controls an
opening of said closing member to substantially stop exhaustion
through the exhausting tube from a predetermined point of time
before cleaning gas is supplied from the gas introducing tube into
the reaction tube to a predetermined point of time after the
cleaning gas is started to be supplied into the reaction tube such
that there exists a state in which exhaustion from the gas
exhausting tube is stopped while the cleaning gas is supplied from
the gas introducing tube into the reaction tube to repeat a first
stage fills the reaction tube with the cleaning gas under control
of the controller and a second stage which thereafter exhausts gas
from the reaction tube at least once.
[0052] In the second stage, since a reaction material after the
cleaning reaction hinders subsequent cleaning reaction, it is
possible to enhance the cleaning efficiency by once exhausting gas.
The number of repetitions of the first and second stages depends on
a film thickness and the like.
[0053] A substrate processing apparatus according to a third
preferred aspect of the present invention comprises: [0054] a
reaction tube; [0055] a gas introducing tube which is in
communication with the reaction tube; [0056] a cleaning gas supply
member which supplies cleaning gas to the gas introducing tube, and
[0057] a controller which controls an opening of the closing member
to substantially stop exhaustion through the exhausting tube from a
predetermined point of time before cleaning gas is supplied from
the gas introducing tube into the reaction tube to a point of time
when several seconds are elapsed after starting of supply of the
cleaning gas into the reaction tube such that there exists a state
in which exhaustion from the gas exhausting tube is stopped while
the cleaning gas is supplied by the cleaning gas supply member
through the gas introducing tube into the reaction tube.
[0058] Preferrably, a semiconductor device is produced through
steps including a substrate processing step which uses one of the
above-mentioned substrate processing apparatus according to first
to third preferred aspect of the present invention, and which
substantially stops exhaustion through the exhausting tube from a
predetermined point of time before the cleaning gas is supplied
from the gas introducing tube into the reaction tube to a point of
time when several seconds are elapsed after starting of supply of
the cleaning gas into the reaction tube such that there exists a
state in which exhaustion from the gas exhausting tube is stopped
while the cleaning gas is supplied from the gas introducing tube
into the reaction tube to fill the reaction tube with the cleaning
gas under control of the controller.
[0059] Next, preferred embodiments of the present invention will be
explained with reference to the drawings.
[0060] FIG. 1 shows a substrate processing apparatus 20 according
to the embodiment of the invention. The substrate processing
apparatus 20 is of a vertical type and has a casing 22 in which
essential members are disposed. A pod stage 24 is connected to the
casing 22, and the pod 26 is transferred to the pod stage 24. In
the pod 26, 25 substrates are accommodated for example, and the pod
26 is closed with a lid (not shown) and in this state, the pod 26
is set on the pod stage 24.
[0061] A pod transfer device 28 is disposed in the casing 22 at a
position opposed to the pod stage 24. Pod shelves 30, a pod opener
32 and a substrate-number detector 34 are disposed in the vicinity
of the transfer device 28. The pod transfer device 28 transfers the
pod 26 between the pod stage 24, the pod shelves 30 and the pod
opener 32. The pod opener 32 opens the lid of the pod 26, and the
substrate-number detector 34 detects the number of substrates in
the opened pod 26.
[0062] A substrate carrying device 36, a notch aligner 38 and a
substrate supporting body 40 (boat) are further disposed in the
casing 22. The substrate carrying device 36 has an arm 42 capable
of taking out five substrates for example, and the substrate
carrying device 36 transfers the substrates between the pod 26
placed on the pod opener 32, the notch aligner 38 and the substrate
supporting body 40 by moving the arm 42. The notch aligner 38
detects a notch and orientation flat formed in the substrates and
aligns the substrates.
[0063] FIG. 2 shows a reaction furnace 50. The reaction furnace 50
includes a reaction tube 52. The substrate supporting body is
inserted in the reaction tube 52. A lower portion of the reaction
tube 52 is opened so that the substrate supporting body can be
inserted therethrough, and this opened portion is tightly closed by
a seal cap 54 (shown in FIG. 1 also). A heater 56 (shown in FIG. 3)
is disposed around the reaction tube 52. A gas introducing tube 58
for supplying reaction gas and cleaning gas and a gas exhausting
tube 60 for exhausting reaction gas and cleaning gas are connected
to the reaction tube 52. Gas supplied from the gas introducing tube
58 is supplied into the reaction tube 52 from a large number of
holes 64 of a gas nozzle 62 formed in the reaction tube 52. The gas
exhausting tube 60 is provided with a closing member 66 comprising
a pressure-adjusting valve for example, and the closing member 66
has a shut-off function.
[0064] Next, a substrate processing process by means of the
substrate processing apparatus 20 having the above-described
structure will be explained.
[0065] First, if the pod 26 holding a plurality of substrates
therein is set on the pod stage 24, the pod 26 is transferred from
the pod stage 24 to the pod shelf 30 and is stocked on the pod
shelf 30. Next, the pod 26 stocked on the pod shelf 30 is
transferred to the pod opener 32 by the pod transfer device 28, the
lid of the pod 26 is opened by the pod opener 32, and the number of
substrates accommodated in the pod 26 is detected by the
substrate-number detector 34.
[0066] Next, the substrate carrying device 36 takes the substrates
out from the pod 26 located at the position of the pod opener 32,
and moves the pod 26 to the notch aligner 38. In the notch aligner
38, notches of the substrates are detected while rotating the
substrates, and the plurality of substrates are aligned to the same
position based on the detected information. Next, the substrate
carrying device 36 takes the substrates out from the notch aligner
38 and moves them to the substrate supporting body 40.
[0067] If the one batch of substrates is moved to the substrate
supporting body 40 in this manner, the substrate supporting body 40
in which the plurality of substrates are accommodated is loaded
into the reaction furnace 50 whose temperature is set to a
predetermined value, and the reaction tube 52 is tightly closed by
the seal cap 54. Next, reaction gas is supplied into the reaction
tube 52 from the gas introducing tube 58. Then, the substrates are
processed in accordance with preset temperature rising and lowering
program while monitoring a temperature in the reaction tube 52.
[0068] If the substrate processing is completed, the temperature is
lowered to a predetermined value and then, the substrate supporting
body 40 is unloaded from the reaction furnace 50, and the substrate
supporting body 40 is brought into a standby state at a
predetermined position until all of the substrates supported by the
substrate supporting body 40 are cooled. Next, if the substrates of
the standby substrate supporting body 40 are cooled to a
predetermined temperature, the substrate carrying device 36 takes
the substrates out from the substrate supporting body 40, and
transfers the substrates to an empty pod 26 which is set to the pod
opener 32. Next, the transfer device 28 transfers the pod 26
holding the substrates therein to the pod shelf 30 and further
transfers the pod 26 to the pod stage 24 and the operation is
completed.
[0069] FIG. 3 shows a gas system of the above-described substrate
processing apparatus.
[0070] A first storage tank 68 storing N2 gas for purging is
connected to the reaction tube 52 through a first manual valve 70,
a first open/close valve 72, first flow-rate control valve 74, the
second open/close valve 76 and the gas introducing tube 58. A
second storage tank 78 storing cleaning gas is connected to the
reaction tube 52 through a second manual valve 80, a third
open/close valve 82, a second flow-rate control valve 84, a fourth
open/close valve 86 and the gas introducing tube 58. A third
storage tank 88 storing first reaction gas is connected to the
reaction tube 52 through a third manual valve 90, a fifth
open/close valve 92, a third flow-rate control valve 94, a sixth
open/close valve 96 and the gas introducing tube 58. A third
storage tank 98 storing second reaction gas is connected to the
reaction tube 52 through a fourth manual valve 100, a seventh
open/close valve 102, a fourth flow-rate control valve 104, an
eighth open/close valve 106 and the gas introducing tube 58.
[0071] The gas exhausting tube 60 having the closing member 66 is
connected to a dry pump 108. The reaction tube 52 is evacuated by
the operation of the dry pump 108.
[0072] A controller (control section) 110 comprises a computer for
example, and controls the opening and closing operations of the
open/close valves 72, 76, 82, 86, 92, 96, 102 and 106, the flow
rates of the flow-rate control valves 74, 84, 94 and 104, electric
power to the heater 56, opening of the closing member 66, the
actuation of the dry pump 108, and the like.
[0073] Next, the cleaning operation will be explained.
[0074] If the processing of several batches of substrates is
repeated several times in the above-described manner, reaction
by-product is deposited in a reaction space, e.g., on an inner wall
of the reaction tube 52, the deposited by-product is peeled off
with time, and this becomes particles, and there is a problem that
the particles attached onto the substrate and deteriorate the
yield.
[0075] Therefore, it is necessary to clean the reaction space
periodically. In this embodiment, etching gas (e.g., NF.sub.3 gas)
is supplied as the cleaning gas, thereby carrying out self-cleaning
in the reaction space. Although the cleaning operation is not shown
in FIG. 2, the cleaning is carried out in a state in which the
substrate supporting body is inserted into the reaction tube 52,
and the by-product deposited on the substrate supporting body is
also removed.
[0076] FIG. 4 is a flowchart showing an example of the control
operation in cleaning steps of the controller 110. FIG. 5 shows a
time chart in the control operation example.
[0077] First, in step S10, the closing member 66 is closed in a
state in which a pressure in the reaction tube 52 is set to a base
pressure. In step S12, the fourth open/close valve 86 is opened. In
step S14, a flow rate of the second flow-rate control valve 84 is
set to a first set value. This first set value is 1.5 slm for
example. In step S16, the third open/close valve 82 is opened and
the supply of etching gas is started (t0 in FIG. 5). With this, a
pressure in the reaction tube 52 gradually rises. This state is
maintained for time t1, and the pressure in the reaction tube 52
when the time t1 is elapsed reaches p1. The time t1 is 25 seconds
for example, and the p1 is 10 Torr for example. If the time t1 is
elapsed, in next step S18, the flow rate of the second flow-rate
control valve 84 is set to a second set value. The second set value
is 0.25 slm for example. With this, the pressure in the reaction
tube 52 is increased from p1 to p2 or maintained at p1. In this
embodiment, the p2 is 10 Torr and is equal to the p1. This state is
maintained for time t2. The time t2 is 65 seconds for example.
[0078] If the flow rate of the second flow-rate control valve 84 is
reduced from the first set value (e.g., 1.5 slm) to the second set
value (e.g., 0.25 slm), the following effects can be obtained.
[0079] (a) By supplying the etching gas with the first set value
which is higher than the second set value, the pressure can be
quickly increased to such a value that effective etching speed can
be obtained.
[0080] (b) By supplying the etching gas with the second set value
which is lower than the first set value, concentration of the
etching gas in the vicinity of the holes 64 of the gas nozzle 62
can be reduced, and the uniformity of the etching gas in the
reaction tube can be enhanced.
[0081] (c) By supplying the etching gas with the second set value
which is lower than the first set value, it is possible to add
etching gas to supplement the etching gas consumed by the etching,
and to prevent a partial pressure of the etching gas caused by the
etching from being lowered. In a state in which a pressure in the
reaction tube becomes p2, this state may be maintained for time t4.
The time t4 is 45 seconds for example.
[0082] The procedure up to here is a first stage. The etching gas
is allowed to flow into the reaction tube 52 from the large number
of holes 64 through the gas nozzle 62 extending from the gas
introducing tube 58 in the longitudinal direction of the reaction
tube 52. In this state, if the closing member 66 of the gas
exhausting tube 60 is closed, the gas fills in the reaction tube 52
and is contained therein.
[0083] With this, a deviated flow of etching gas 112 toward the gas
exhausting tube 60 is moderated, the etching gas is diffused in the
reaction tube 52 entirely, and the partial pressure of the etching
gas 112 in the reaction tube 52 becomes uniform.
[0084] In FIG. 2, a reference number 114 shows a diffusing state of
the etching gas 112 after it is supplied into the reaction tube 52.
A reference number 116 shows a phantom region where the etching gas
112 is entirely diffused in the reaction tube 52 uniformly.
[0085] Concerning the variation in partial pressure of the etching
gas in upstream and downstream of the gas by consumption of the
etching gas 112 and product gas by the etching, the partial
pressure of the etching gas becomes uniform by the etching gas and
the diffusion of the product gas by the etching gas.
[0086] That is, removal of the reaction by-product deposited on the
inner wall of the reaction tube 52 can be expressed by the
following principle. Si.sub.3N.sub.4 which is the reaction
by-product (solid state) and 4NF.sub.3 which is the etching gas are
reacted with each other and product gas of the Si.sub.3N.sub.4 and
4NF.sub.3 is produced, thereby removing the reaction
by-product.
[0087] A temperature in the reaction tube 52 during this is
maintained at 630.degree. C.
[0088] When there exists a gas flow in the reaction tube as in the
conventional technique, in an upstream portion of the gas flow, NF3
is consumed but the Si.sub.3N.sub.4 and 4NF.sub.3 exist
excessively, and the partial pressures of the etching gas are
different in the upstream portion and downstream portion of the gas
flow.
[0089] If the gas flow is not formed and the gas is contained as in
the embodiment of the present invention, however, since the
NF.sub.3, SiF.sub.4 and N.sub.2 are prone to be diffused, the
partial pressures thereof become equal, and uniform etching gas can
be supplied into the reaction tube 52. With this, uniform cleaning
can be carried out.
[0090] Since gas is not exhausted during the supply of etching gas
in the first stage, although the pressure in the reaction tube 52
rises, the etching speed is also increased by this pressure
rise.
[0091] If time t2 is elapsed after the second flow-rate control
valve 84 is set to the second set value in step S18 as described
above, the procedure is proceeded to step S20. The third open/close
valve 82 is closed in step S20, the fourth open/close valve 86 is
closed in step S22, and the closing member 66 is opened in step
S24. With this, the etching gas in the reaction tube 52 is
exhausted through the gas exhausting tube 60, and a pressure in the
reaction tube 52 is abruptly reduced to the base pressure.
[0092] The procedure up to here is a second stage. The etching gas
and the product gas are exhausted.
[0093] In step S26, it is judged whether the processes of the first
and second stages are repeated predetermined times. If it is judged
in step S26 that the processes are repeated the predetermined
times, the procedure is proceeded to a next process (substrate
processing). On the other hand, if it is judged in step S26 that
the processes are not repeated the predetermined times, the
procedure is returned to step S10, and the processes of the first
and second stages are executed repeatedly. In step S22, time t3 is
elapsed after the closing member 66 is opened, and the etching gas
and the product gas in the reaction tube 52 are sufficiently
exhausted, and the closing member 66 is closed in the next cycle.
This time t3 is four seconds for example.
[0094] As described above, uniform cleaning can be carried out by
dividing the cleaning step in the reaction tube 52 into the first
stage and the second stage and carrying out the stages, but if it
is desired to further enhance the cleaning efficiency, more uniform
etching with no remainder of etching can be carried out by
repeating the first and second stages at least two times or
more.
[0095] According to the cleaning method provided by the embodiment
of this invention, the uniform cleaning in the reaction tube can be
carried out.
[0096] If a substrate processing apparatus in which the interior of
the reaction tube is self-cleaned in the cleaning step is used, it
is possible to produce a high quality semiconductor device.
[0097] The present invention is not limited to the above-described
embodiment, and various modifications can be made.
[0098] That is, it is unnecessary to completely stop the exhaust of
gas in the first stage, and the etching gas may be supplied while
exhausting the etching gas only if the exhausting amount is set to
such a degree that the flow of etching gas supplied into the
reaction tube does not become nonuniform and the uniform diffusion
of gas is not affected.
[0099] If the first stage is again carried out when the second
stage is carried out or after the second stage is carried out,
etching gas may slightly be supplied instead of completely stopping
the supply of the etching gas. If the first stage is not carried
out again after the second stage, it is preferable that the supply
of the etching gas is completely stopped and the gas is exhausted
because the gas (etching gas) is not remained for the next
processing.
[0100] As described, only if the cleaning gas is uniformly diffused
in the reaction tube at the time of the first stage, this method
can variously be modified.
[0101] FIG. 6 shows another embodiment. This other embodiment is
different from the previous embodiment in the following point. That
is, the closing member is closed and exhausting operation of gas is
stopped before the start of supply of cleaning gas in the previous
embodiment, but the closing member is closed and exhausting
operation of gas is stopped after the start of supply of cleaning
gas in this other embodiment.
[0102] That is, in this embodiment, steps S12, S14 and S16 are
first executed, and cleaning gas is supplied to the reaction tube.
Then, after predetermined time is elapsed, step S10 is executed and
the exhausting operation is stopped. In this predetermined time,
time required for closing the closing member and time required for
easily diffuing cleaning gas into the reaction tube substantially
entirely are taken into consideration. For example, if time
required for closing the closing member is two seconds and time
required for easily diffusing cleaning gas into the reaction tube
substantially entirely are taken into consideration is five second,
the total is seven seconds, and it is preferable that the
exhausting operation is stopped within the seven seconds. A reason
why a margin of five seconds is required is that since the
exhausting operation is stopped after a flow of gas is produced in
the reaction tube, if a distance between a supply port (e.g.,
outlet of the fourth open/close valve 86) of gas and an exhaust
port (inlet of the gas exhausting tube 60) is long and the path is
complicated, it is possible to allow the cleaning gas to reach the
reaction tube quickly.
[0103] In the explanation of the above embodiments, the substrate
processing apparatus is described as a batch type apparatus which
processes a plurality of substrates, but the substrate processing
apparatus is not limited to this, and a single substrate-feeding
type apparatus may also be employed.
[0104] The entire disclosures of Japanese Patent Application No.
2002-92733 filed on Mar. 28, 2002 and Japanese Patent Application
No. 2002-366250 filed on Dec. 18, 2002 including specifications,
claims, drawings and abstracts are incorporated herein by reference
in their entireties.
[0105] Although various exemplary embodiments have been shown and
described, the invention is not limited to the embodiments shown.
Therefore, the scope of the invention is intended to be limited
solely by the scope of the claims that follow.
* * * * *