U.S. patent application number 11/501793 was filed with the patent office on 2007-03-01 for vacuum evacuation device and method, and substrate processing apparatus and method.
Invention is credited to Takanobu Asano, Masafumi Inoue, Katsutoshi Ishii, Ken Nakao, Hiroaki Ogamino, Shinichi Sekiguchi, Kota Umezawa, Tadashi Urata, Katsuaki Usui, Hironobu Yamasaki.
Application Number | 20070048145 11/501793 |
Document ID | / |
Family ID | 37804365 |
Filed Date | 2007-03-01 |
United States Patent
Application |
20070048145 |
Kind Code |
A1 |
Ishii; Katsutoshi ; et
al. |
March 1, 2007 |
Vacuum evacuation device and method, and substrate processing
apparatus and method
Abstract
A vacuum evacuation device 2 of the invention comprises a vacuum
pump 4,5 for exhausting a gas G2 in a process chamber 21 into which
a process gas G1 is introduced and in which a process reaction is
performed, to form a vacuum in said process chamber 21; and a
control means 6 for performing a first control that regulates the
rotational speed of said vacuum pump 4,5 such that a pressure
condition in said process chamber 21 reaches a pressure condition
suitable for said process reaction during said process reaction,
wherein said control means 6 calculates a specified rotational
speed for said vacuum pump 4,5 based on process information related
to said process reaction, and performs a second control that brings
said vacuum pump 4,5 to said specified rotational speed before said
first control. The vacuum evacuation device 2 is capable of
bringing the pressure in a process chamber 21 to the target
pressure in a short period without a vacuum pump 4,5 being
overloaded, regardless of the process reaction condition.
Inventors: |
Ishii; Katsutoshi;
(Yamanashi, JP) ; Nakao; Ken; (Yamanashi, JP)
; Asano; Takanobu; (Iwate, JP) ; Umezawa;
Kota; (Yamanashi, JP) ; Ogamino; Hiroaki;
(Tokyo, JP) ; Urata; Tadashi; (Tokyo, JP) ;
Usui; Katsuaki; (Tokyo, JP) ; Inoue; Masafumi;
(Tokyo, JP) ; Sekiguchi; Shinichi; (Tokyo, JP)
; Yamasaki; Hironobu; (Tokyo, JP) |
Correspondence
Address: |
WENDEROTH, LIND & PONACK, L.L.P.
2033 K STREET N. W.
SUITE 800
WASHINGTON
DC
20006-1021
US
|
Family ID: |
37804365 |
Appl. No.: |
11/501793 |
Filed: |
August 10, 2006 |
Current U.S.
Class: |
417/44.2 |
Current CPC
Class: |
F04D 27/0261 20130101;
F04D 19/042 20130101; Y02B 30/70 20130101 |
Class at
Publication: |
417/044.2 |
International
Class: |
F04B 49/06 20060101
F04B049/06 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 12, 2005 |
JP |
2005-234236 |
Jul 24, 2006 |
JP |
2006-201030 |
Claims
1. A vacuum evacuation device comprising: a vacuum pump for
exhausting a gas in a process chamber into which a process gas is
introduced and in which a process reaction is performed, to form a
vacuum in said process chamber; and control means for performing a
first control that regulates a rotational speed of said vacuum pump
such that a pressure condition in said process chamber reaches a
pressure condition suitable for said process reaction during said
process reaction, wherein said control means calculates a specified
rotational speed for said vacuum pump based on process information
related to said process reaction, and performs a second control
that brings said vacuum pump to said specified rotational speed
before said first control.
2. A vacuum evacuation device comprising: a first vacuum pump for
exhausting a gas in a process chamber into which a process gas is
introduced and in which a process reaction is performed, to form a
vacuum in said process chamber; a second vacuum pump connected to
the exhaust side of said first vacuum pump to exhaust a gas from
said exhaust side to form a vacuum in said process chamber; and
control means for performing a first control that regulates a
rotational speed of one of said first vacuum pump and said second
vacuum pump such that a pressure condition in said process chamber
reaches a pressure condition suitable for said process reaction
during said process reaction, wherein said control means calculates
a specified rotational speed for said one vacuum pump based on
process information related to said process reaction, and performs
a second control that brings said one vacuum pump to said specified
rotational speed before said first control.
3. A vacuum evacuation device comprising: a first vacuum pump for
exhausting a gas in a process chamber into which a process gas is
introduced and in which a process reaction is performed, to form a
vacuum in said process chamber; a second vacuum pump connected to
an exhaust side of said first vacuum pump to exhaust a gas from
said exhaust side to form a vacuum in said process chamber; and
control means for performing a first control that regulates a
rotational speed of said first vacuum pump such that a pressure
condition in said process chamber reaches a pressure condition
suitable for said process reaction during said process reaction,
and regulates a rotational speed of said second vacuum pump such
that a pressure condition on said exhaust side reaches a specified
pressure condition during said process reaction, wherein said
control means calculates a specified rotational speed for at least
one of said first vacuum pump and said second vacuum pump based on
process information related to said process reaction, and performs
a second control that brings said at least one vacuum pump to said
specified rotational speed before said first control.
4. A substrate processing apparatus comprising: a vacuum evacuation
device according to claim 1; and a process chamber into which said
process gas is introduced and in which a process reaction is
performed, wherein said process chamber receives a substrate so
that a surface of said substrate is processed by said process
reaction.
5. A substrate processing apparatus comprising: a vacuum evacuation
device according to claim 2; and a process chamber into which said
process gas is introduced and in which a process reaction is
performed, wherein said process chamber receives a substrate so
that the surface of said substrate is processed by said process
reaction.
6. A substrate processing apparatus comprising: a vacuum evacuation
device according to claim 3; and a process chamber into which said
process gas is introduced and in which a process reaction is
performed, wherein said process chamber receives a substrate so
that the surface of said substrate is processed by said process
reaction.
7. A vacuum evacuation method comprising: a reaction step of
introducing a process gas into a process chamber and performing a
process reaction therein; an evacuation step of exhausting a gas in
said process chamber by a vacuum pump and forming a vacuum in said
process chamber; a first control step of controlling a pressure in
said process chamber by regulating a rotational speed of said
vacuum pump such that said pressure reaches a degree of vacuum
suitable for said process reaction; a calculation step of
calculating a specified rotational speed for said vacuum pump based
on process information related to said process reaction; and a
second control step of bringing said vacuum pump to said specified
rotational speed before said first control step.
8. A vacuum evacuation method comprising: a reaction step of
introducing a process gas into a process chamber and performing a
process reaction therein; a first evacuation step of exhausting a
gas in said process chamber by a first vacuum pump and forming a
vacuum in said process chamber; a second evacuation step of
exhausting a gas on an exhaust side of said first vacuum pump by a
second vacuum pump and forming a vacuum in said process chamber; a
first control step of controlling a pressure condition in said
process chamber by regulating a rotational speed of one of said
first vacuum pump and said second vacuum pump such that said
pressure condition reaches a pressure condition suitable for said
process reaction during said process reaction; a calculation step
of calculating a specified rotational speed for said one vacuum
pump based on process information related to said process reaction;
and a second control step of bringing said one vacuum pump to said
specified rotational speed before said first control step.
9. A vacuum evacuation method comprising: a reaction step of
introducing a process gas into a process chamber and performing a
process reaction therein; a first evacuation step of exhausting a
gas in said process chamber by a first vacuum pump and forming a
vacuum in said process chamber; a second evacuation step of
exhausting a gas on an exhaust side of said first vacuum pump by a
second vacuum pump and forming a vacuum in said process chamber; a
first control step of controlling a pressure condition in said
process chamber by regulating a rotational speed of a first vacuum
pump such that said pressure condition in said process chamber
reaches a pressure condition suitable for said process reaction
after the introduction of said process gas; a second control step
of controlling a pressure condition on said exhaust side by
regulating a rotational speed of a second vacuum pump such that
said pressure condition on said exhaust side reaches a specified
pressure condition after the introduction of said process gas; a
calculation step of calculating a specified rotational speed for at
least one of said first vacuum pump and said second vacuum pump
based on process information related to said process reaction; and
a third control step of bringing at least one vacuum pump to said
specified rotational speed before said first control step and said
second control step.
10. The vacuum evacuation method according to claim 9, wherein said
first control step is performed after said pressure condition on
said exhaust side of said first vacuum pump reaches a specified
pressure condition in said second control step.
11. A substrate processing method comprising: a receiving step of
receiving a substrate in a process chamber; an evacuation step of
evacuating said process chamber according to a vacuum evacuation
method according to claim 7; and a substrate processing step of
processing a surface of said substrate by said process
reaction.
12. A substrate processing method comprising: a receiving step of
receiving a substrate in a process chamber; an evacuation step of
evacuating said process chamber according to a vacuum evacuation
method according to claim 8; and a substrate processing step of
processing a surface of said substrate by said process
reaction.
13. A substrate processing method comprising: a receiving step of
receiving a substrate in a process chamber; an evacuation step of
evacuating said process chamber according to a vacuum evacuation
method according to claim 9; and a substrate processing step of
processing a surface of said substrate by said process
reaction.
14. A substrate processing method comprising: a receiving step of
receiving a substrate in a process chamber; an evacuation step of
evacuating said process chamber according to a vacuum evacuation
method according to claim 10; and a substrate processing step of
processing a surface of said substrate by said process
reaction.
15. A vacuum evacuation device comprising: a vacuum pump for
exhausting a gas in a process chamber to form a vacuum in said
process chamber; and control means for performing a first control
that regulates a rotational speed of said vacuum pump such that a
pressure condition in said process chamber reaches a desired
pressure condition, wherein said control means calculates a
specified rotational speed for said vacuum pump based on process
information, and performs a second control that brings said vacuum
pump to said specified rotational speed before said first
control.
16. A vacuum evacuation method comprising: an evacuation step of
exhausting a gas in a process chamber by a vacuum pump and forming
a vacuum in said process chamber; a first control step of
controlling a pressure condition in said process chamber by
regulating a rotational speed of said vacuum pump such that said
pressure condition reaches a desired pressure condition; a
calculation step of calculating a specified rotational speed for
said vacuum pump based on process information related to said
process reaction; and a second control step of bringing said vacuum
pump to said specified rotational speed before said first control
step.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Technical Field
[0002] The present invention relates to a vacuum evacuation device
and method for regulating the rotational speed of a vacuum pump for
exhausting a gas from a process chamber to control the pressure
condition in the process chamber, and a substrate processing
apparatus for evacuating a process chamber using the vacuum
evacuation device to process a substrate in the process chamber and
a substrate processing method for evacuating a Process chamber
using the vacuum evacuation method to process a substrate in the
process chamber.
[0003] 2. Related Art
[0004] As shown in FIG. 21, a conventional vacuum evacuation device
102 includes a turbo molecular pump 104 for exhausting a gas G2
from a process chamber 121 into which a process gas G1 is
introduced at a flow rate regulated by a flow rate regulator 103, a
dry pump 105 for exhausting the gas G2 from the exhaust side of the
turbo molecular pump 104, and a pressure controller 106 for
regulating the rotational speed of the turbo molecular pump 104 to
control the pressure in the process chamber 121. The turbo
molecular pump 104 incorporates a turbo molecular pump motor 104M,
and the dry pump 105 incorporates a dry pump motor 105M.
[0005] The vacuum evacuation device 102 also includes a pressure
gauge 107 for measuring the pressure in the process chamber 121, a
pressure gauge 108 for measuring the pressure on the exhaust side
of the turbo molecular pump 104, an electromagnetic valve 109
installed between the turbo molecular pump 104 and the dry pump 105
to prevent the pressure from being abruptly released to atmospheric
pressure when the dry pump 105 is stopped, a motor control panel
110 for receiving external power E1 and supplying motor power E2 to
the turbo molecular pump motor 104M, and a motor control panel 111
for receiving external power E1 and supplying motor power E3 to the
dry pump motor 105M.
[0006] The pressure gauges 107 and 108 send a pressure signal
indicating the measured pressure to the pressure controller 106.
The pressure controller 106 sends to the motor control panel 110 a
rotational speed command signal i6 to command the rotational speed
of the turbo molecular pump 104, and the motor control panel 110
sends to the turbo molecular pump motor 104M power E2 regulated so
as to achieve the commanded rotational speed. The pressure
controller 106 receives from a process controller (not shown) a
pressure control start signal i1 to start pressure control in the
process chamber 121.
[0007] Next, with reference to FIG. 22 and FIG. 21, the steps of an
operation method for the vacuum evacuation device 102 are described
to perform conventional control of the pressure in the process
chamber 121 by regulating the rotational speed of the turbo
molecular pump 104. When the turbo molecular pump 104 and the dry
pump 105 are respectively operated at the rated rotational speed
(step S101), the process gas G1 is introduced into the process
chamber 121 (step S102), and the process controller (not shown)
sends a pressure control start signal i1 to the pressure controller
106 (step S103). Then, control of the pressure in the process
chamber 121 is started by regulating the speed of the turbo
molecular pump 104 (step S104), and the pressure in the process
chamber 121 reaches the target value (step S105). After that, the
process controller (not shown) sends a pressure control stop signal
(not shown) to the pressure controller 106 (step S106), and the
pressure control in the process chamber 121 is terminated.
[0008] Now, with reference to FIG. 23 and FIG. 21, the conventional
pressure control is described in view of the passage of time. In
the drawing, the horizontal axis represents time, and the vertical
axis represents pressure or rotational speed. Also in the drawing,
the line P102 represents the pressure in the process chamber 121,
the line N104 the rotational speed of the turbo molecular pump 104,
and the line N105 the rotational speed of the dry pump 105. Before
time t101, at which introduction of the process gas G1 introduced
into the process chamber 121 is started, the turbo molecular pump
104 and the dry pump 105 are respectively driven at the rated speed
and the process chamber 121 is under the rated pressure (a
vacuum).
[0009] At time t101, introduction of the process gas G1 into the
process chamber 121 is started, and the pressure in the process
chamber 121 starts increasing. At time t102, a pressure control
start signal i1 is input to the pressure controller 106 to start
pressure control. Since the target pressure is higher than the
rated pressure, the pressure controller 106 performs speed
regulation that decreases the speed of the turbo molecular pump
104. The speed of the dry pump 105 is not regulated but kept at the
rated speed. As the speed of the turbo molecular pump 104
decreases, the pressure in the process chamber 121 increases. The
pressure in the process chamber 121 is fed back from the pressure
gauge 107 to the pressure controller 106, which based on that
pressure performs feedback control so as to increase and decrease
the speed of the turbo molecular pump 104. At time t103, the
pressure in the process chamber 121 reaches the target value and is
kept at the value. At time t104, the process Controller (not shown)
sends a pressure control stop signal (not shown) to the pressure
controller 106, and the pressure control in the process chamber 121
is terminated.
[0010] In the conventional vacuum evacuation device, after a
pressure control start signal to start pressure control in the
process chamber is input to the pressure controller, the speed of
the turbo molecular pump is regulated so as to bring the pressure
in the process chamber to the target pressure.
[0011] However, to prevent the pressure from overshooting during
the pressure control in the process chamber, the pump speed is
regulated so as to decrease from the rated speed. It is thus
necessary to greatly change the pump speed until changes in the
pump speed are reflected in changes in the pressure in the process
chamber.
[0012] Changes in the pressure in the process chamber are primarily
governed by changes in the speed of the turbo molecular pump,
though also influenced by the process condition. The period
required for the pressure in the process chamber to reach the
target pressure is approximately equal to the period required for
the speed of the turbo molecular pump to change.
[0013] However, in case of using a turbo molecular pump including a
magnetic bearing which operates in a vacuum in a non-contacting
manner, for example, deceleration takes time due to the absence of
friction which acts on the rotor. In addition, the pressure in the
process chamber does not change linearly with the change in the
rotational speed of the turbo molecular pump, and it is necessary
to greatly change the rotational speed, which prolongs the control
period to bring the pressure in the process chamber to the target
pressure. Further, in the case where a process condition exceeding
the evacuation capacity of the turbo molecular pump is given while
cleaning the process chamber or the like, increase in the motor
power consumption and a loss of synchronization may be caused due
to overload operation. Rotor runout may also be caused, which could
result in the rotor contacting with the protective bearing.
[0014] In view of the foregoing, it is therefore an object of the
present invention to provide a vacuum evacuation device and method
capable of bringing the pressure in a process chamber to the target
pressure in a short period without a vacuum pump being overloaded,
regardless of the process reaction condition, and to provide a
substrate processing apparatus using the vacuum evacuation device
and a substrate processing method using the vacuum evacuation
method.
SUMMARY OF THE INVENTION
[0015] For the purpose of accomplishing the above object, a vacuum
evacuation device 2 of the invention comprises a vacuum pump 4,5
for exhausting a gas G2 in a process chamber 21 into which a
process gas G1 is introduced and in which a process reaction is
performed, to form a vacuum in said process chamber 21; and a
control means 6 for performing a first control that regulates the
rotational speed of said vacuum pump 4,5 such that a pressure
condition in said process chamber 21 reaches a pressure condition
suitable for said process reaction during said process reaction,
wherein said control means 6 calculates a specified rotational
speed for said vacuum pump 4,5 based on process information related
to said process reaction, and performs a second control that brings
said vacuum pump 4,5 to said specified rotational speed before said
first control, as shown in FIG. 1 for example.
[0016] With this construction, a specified rotational speed for the
vacuum pump is calculated based on process information related to
process reaction, and the vacuum pump can be brought to the
specified speed suitable for the process reaction before the first
control. Therefore, it is possible to bring the process chamber to
a pressure condition suitable for the process reaction in a short
period without the vacuum pump being overloaded in the first
control, regardless of the process reaction condition.
[0017] The phrase "bringing to a pressure condition" refers to, for
example, bringing to a certain pressure value, bringing to and
keeping at a certain pressure value, changing the pressure at a
constant pressure increase or reduction rate, including a pressure
condition where the pressure is changed at a constant pressure
increase or reduction rate, changing the pressure regularly in
terms of time, and changing the pressure increase or reduction rate
regularly in terms of time.
[0018] It is typically necessary to increase the pressure in the
process chamber in order to create a pressure condition suitable
for process reaction, and thus the vacuum pump is decelerated to a
specified rotational speed.
[0019] For the purpose of accomplishing the above object, a vacuum
evacuation device 2 of the invention may comprise a first vacuum
pump 4 for exhausting a gas G2 in a process chamber 21 into which a
process gas G1 is introduced and in which a process reaction is
performed, to form a vacuum in said process chamber 21; a second
vacuum pump 5 connected to the exhaust side of said first vacuum
pump 4 to exhaust a gas G2 from said exhaust side to form a vacuum
in said process chamber 21; and a control means 6 for performing a
first control that regulates the rotational speed of one of said
first vacuum pump 4 and said second vacuum pump 5 such that a
pressure condition in said process chamber 21 reaches a pressure
condition suitable for said process reaction during said process
reaction, wherein said control means 6 calculates a specified
rotational speed for said one vacuum pump 4 or 5 based on process
information related to said process reaction, and performs a second
control that brings said one vacuum pump 4 or 5 to said specified
rotational speed before said first control, as shown in FIG. 1 for
example.
[0020] With this construction, a specified rotational speed for one
of the first vacuum pump and the second vacuum pump is calculated
based on process information related to process reaction, and the
one vacuum pump can be brought to the specified speed suitable for
the process reaction before the first control. Therefore, it is
possible to bring the process chamber to a pressure condition
suitable for the process reaction in a short period without the
vacuum pump being overloaded in the first control, regardless of
the process reaction condition.
[0021] For the purpose of accomplishing the above object, a vacuum
evacuation device 2 of the invention may comprise a first vacuum
pump 4 for exhausting a gas G2 in a process chamber 21 into which a
process gas 21 is introduced and in which a process reaction is
performed, to form a vacuum in said process chamber 21; a second
vacuum pump 5 connected to the exhaust side of said first vacuum
pump 4 to exhaust a gas G2 from said exhaust side to form a vacuum
in said process chamber 21; and a control means 6 for performing a
first control that regulates the rotational speed of said first
vacuum pump 4 such that a pressure condition in said process
chamber 21 reaches a pressure condition suitable for said process
reaction during said process reaction, and regulates the rotational
speed of said second vacuum pump 5 such that a pressure condition
on said exhaust side reaches a specified pressure during said
process reaction, wherein said control means calculates a specified
rotational speed for at least one of said first vacuum pump 4 and
said second vacuum pump 5 based on process information related to
said process reaction, and performs a second control that brings
said at least one vacuum pump 4 or 5 to said specified rotational
speed before said first control as shown in FIG. 1 for example.
[0022] With this construction, a specified rotational speed for at
least one of the first vacuum pump and the second vacuum pump is
calculated based on process information related to process
reaction, and the at least one vacuum pump can be brought to the
specified speed suitable for the process reaction before the first
control. Therefore, it is possible to bring the process chamber to
a pressure condition suitable for the process reaction in a short
period without the vacuum pump being overloaded in the first
control, regardless of the process reaction condition. The control
means may calculate respective specified rotational speeds for the
first vacuum pump and the second vacuum pump based on process
information related to the process reaction, and may perform a
second control that brings the first vacuum pump and the second
vacuum pump to the respective specified rotational speeds before
the first control. In this way, it is possible to appropriately
perform control over a wider pressure range and control involving
pressure changes with a high pressure change rate.
[0023] For the purpose of accomplishing the above object, a
substrate processing apparatus 1 of the invention may comprise the
vacuum evacuation device 2; and a process chamber 21 into which
said process gas G1 is introduced and in which a process reaction
is performed, wherein said process chamber 21 receives a substrate
W so that the surface of said substrate W is processed by said
process reaction as shown in FIGS. 1, 19 for example.
[0024] With this construction, it is possible to bring the process
chamber to a pressure condition suitable for process reaction in a
short period without the vacuum pump being overloaded in the first
control, regardless of the process reaction condition. It is thus
possible to reduce the time required to process the substrate.
[0025] For the purpose of accomplishing the above object, a vacuum
evacuation method of the invention may comprise a reaction step of
introducing a process gas G1 into a process chamber 21 and
performing a process reaction therein; an evacuation step of
exhausting a gas G2 in said process chamber 21 by a vacuum pump 4,5
and forming a vacuum in said process chamber 21; a first control
step of controlling a pressure in said process chamber 21 by
regulating a rotational speed of said vacuum pump 4, 5 such that
said pressure reaches a degree of vacuum suitable for said process
reaction; a calculation step of calculating a specified rotational
speed for said vacuum pump 4,5 based on process information related
to said process reaction; and a second control step of bringing
said vacuum pump 4,5 to said specified rotational speed before said
first control step, as shown in FIG. 1 for example.
[0026] For the purpose of accomplishing the above object, a vacuum
evacuation method of the invention may comprise a reaction step of
introducing a process gas G1 into a process chamber 21 and
performing a process reaction therein; a first evacuation step of
exhausting a gas G2 in said process chamber 21 by a first vacuum
pump 4 and forming a vacuum in said process chamber 21; a second
evacuation step of exhausting a gas G2 on an exhaust side of said
first vacuum pump 4 by a second vacuum pump 5 and forming a vacuum
in said process chamber 21; a first control step of controlling a
pressure condition in said process chamber 21 by regulating a
rotational speed of one of said first vacuum pump 4 and said second
vacuum pump 5 such that said pressure condition reaches a pressure
condition suitable for said process reaction during said process
reaction; a calculation step of calculating a specified rotational
speed for said one vacuum pump 4 or 5 based on process information
related to said process reaction; and a second control step of
bringing said one vacuum pump 4 or 5 to said specified rotational
speed before said first control step, as shown in FIG. 1 for
example.
[0027] For the purpose of accomplishing the above object, a vacuum
evacuation method of the invention may comprise, a reaction step of
introducing a process gas G1 into a process chamber 21 and
performing a process reaction therein; a first evacuation step of
exhausting a gas G2 in said process chamber 21 by a first vacuum
pump 4 and forming a vacuum in said process chamber 21; a second
evacuation step of exhausting a gas G2 on an exhaust side of said
first vacuum pump 4 by a second vacuum pump 5 and forming a vacuum
in said process chamber 21; a first control step of controlling a
pressure condition in said process chamber by regulating a
rotational speed of a first vacuum pump 4 such that said pressure
condition in said process chamber 21 reaches a pressure condition
suitable for said process reaction after the introduction of said
process gas G1; a second control step of controlling a pressure
condition on said exhaust side by regulating a rotational speed of
a second vacuum pump 5 such that said pressure condition on said
exhaust side reaches a specified pressure condition after the
introduction of said process gas G1; a calculation step of
calculating a specified rotational speed for at least one of said
first vacuum pump 4 and said second vacuum pump 5 based on process
information related to said process reaction; and a third control
step of bringing at least one vacuum pump 4 or 5 to said specified
rotational speed before said first control step and said second
control step, as shown in FIG. 1 for example.
[0028] In the vacuum evacuation method of the invention, said first
control step may be performed after said pressure condition on said
exhaust side of said first vacuum pump 4 reaches a specified
pressure condition in said second control step, as shown in FIG. 1
for example.
[0029] The substrate processing method of the invention may further
comprise a receiving step of receiving a substrate W in a process
chamber 21; an evacuation step of evacuating said process chamber
21 according to the vacuum evacuation method described just above;
and a substrate processing step of processing a surface of said
substrate W by said process reaction, as shown in FIG. 1, 19 for
example.
[0030] The term "substrate" refers to semiconductor wafer, LCD
substrate, etc. The phrase "processing a surface of a substrate"
refers to forming a film, etching, ashing, etc.
[0031] For the purpose of accomplishing the above object, a vacuum
evacuation device 2 of the invention may comprise a vacuum pump 4,5
for exhausting a gas G2 in a process chamber 21 to form a vacuum in
said process chamber 21; and a control means 6 for performing a
first control that regulates the rotational speed of said vacuum
pump 4,5 such that a pressure condition in said process chamber 21
reaches a desired pressure condition, wherein said control means 6
calculates a specified rotational speed for said vacuum pump 4,5
based on process information, and performs a second control that
brings said vacuum pump 4,5 to said specified rotational speed
before said first control, as shown in FIG. 1 for example.
[0032] With this construction, a specified rotational speed for the
vacuum pump is calculated based on process information, and the
vacuum pump can be brought to the specified speed before the first
control. Therefore, it is possible to bring the process chamber to
a desired pressure condition in a short period without the vacuum
pumps being overloaded in the first control.
[0033] The vacuum pump may include a first vacuum pump for
exhausting a gas in the process chamber to form a vacuum in the
process chamber, and a second vacuum pump connected to the exhaust
side of the first vacuum pump to exhaust a gas from the exhaust
side to form a vacuum in the process chamber. The control means may
regulate the rotational speed of one of the first vacuum pump and
the second vacuum pump. The control means may calculate a specified
rotational speed for the one vacuum pump based on process
information, and performs a second control that brings the one
vacuum pump to the specified rotational speed before the first
control described just above.
[0034] Also, the control means may perform a first control that
regulates the rotational speed of the first vacuum pump such that a
pressure condition in said process chamber reaches a desired
pressure condition, and regulates the rotational speed of the
second vacuum pump such that a pressure condition on the exhaust
side reaches a specified pressure condition.
[0035] For the purpose of accomplishing the above object, a vacuum
evacuation method of the invention may comprise, an evacuation step
of exhausting a gas G2 in a process chamber 21 by a vacuum pump 4,5
and forming a vacuum in said process chamber 21; a first control
step of controlling a pressure condition in said process chamber 21
by regulating a rotational speed of said vacuum pump 4,5 such that
said pressure condition reaches a desired pressure condition; a
calculation step of calculating a specified rotational speed for
said vacuum pump 4,5 based on process information related to said
process reaction; and a second control step of bringing said vacuum
pump 4,5 to said specified rotational speed before said first
control step, as shown in FIG. 1 for example.
[0036] As described above, according to the present invention, the
control means calculates a specified rotational speed for the
vacuum pump based on process information related to process
reaction, and the vacuum pump can be brought to the specified speed
suitable for the process reaction before the first control.
Therefore, it is possible to bring the process chamber to a
pressure condition suitable for the process reaction in a short
period without the vacuum pump being overloaded in the first
control, regardless of the process reaction condition.
[0037] The present application is based on the Japanese Patent
Application No. 2005-234236 filed on Aug. 12, 2005 in Japan, the
Japanese Patent Application No. 2006-201030 filed on Jul. 24, 2006.
These Japanese Patent Applications are hereby incorporated in its
entirety by reference into the present application.
[0038] The present application will become more fully understood
from the detailed description given hereinbelow. However, the
detailed description and the specific embodiment are illustrated of
desired embodiments of the present invention and are described only
for the purpose of explanation. Various changes and modifications
will be apparent to those ordinary skilled in the art of the basic
of the detailed description.
[0039] The applicant has no intention to give to public any
disclosed embodiment. Among the disclosed changes and
modifications, those which may not literally fall within the scope
of the patent claims constitute, therefore, a part of the present
invention in the sense of doctrine of equivalents.
[0040] The use of the terms "a" and "an" and "the" and similar
referents in the context of describing the invention (especially in
the context of the following claims) are to be construed to cover
both the singular and the plural, unless otherwise indicated herein
or clearly contradicted by context. The use of any and all
examples, or exemplary language (e.g., "such as") provided herein,
is intended merely to better illuminate the invention and does not
pose a limitation on the scope of the invention unless otherwise
claimed.
BRIEF DESCRIPTION OF THE DRAWING
[0041] FIG. 1 is a block diagram showing the structure of a vacuum
evacuation device according to a first embodiment of the present
invention.
[0042] FIG. 2 is a flowchart showing the steps of a first operation
method for the vacuum evacuation device of FIG. 1.
[0043] FIG. 3 is a graph showing the timeline of the first
operation method for the vacuum evacuation device of FIG. 1.
[0044] FIG. 4 is a flowchart showing the steps of a second
operation method for the vacuum evacuation device of FIG. 1.
[0045] FIG. 5 is a graph showing the timeline of the second
operation method for the vacuum evacuation device of FIG. 1.
[0046] FIG. 6 is a flowchart showing the steps of a third operation
method for the vacuum evacuation device of FIG. 1.
[0047] FIG. 7 is a graph showing the timeline of the third
operation method for the vacuum evacuation device of FIG. 1.
[0048] FIG. 8 is a flowchart showing the steps of a fourth
operation method for the vacuum evacuation device of FIG. 1.
[0049] FIG. 9 is a graph showing the timeline of the fourth
operation method for the vacuum evacuation device of FIG. 1.
[0050] FIG. 10 is a detailed sectional block view showing a portion
of a process chamber of the vacuum evacuation device of FIG. 1.
[0051] FIG. 11 is a graph showing pressure changes over time in the
third operation method for the vacuum evacuation device of FIG.
1.
[0052] FIG. 12 is a block diagram showing the structure of a vacuum
evacuation device according to a second embodiment of the present
invention.
[0053] FIG. 13 is a flowchart showing the steps of a fifth
operation method for the vacuum evacuation device of FIG. 12.
[0054] FIG. 14 is a graph showing the timeline of the fifth
operation method for the vacuum evacuation device of FIG. 12.
[0055] FIG. 15 is a flowchart showing the steps of a sixth
operation method for the vacuum evacuation device of FIG. 12.
[0056] FIG. 16 is a graph showing the timeline of the sixth
operation method for the vacuum evacuation device of FIG. 12.
[0057] FIG. 17 is a flowchart showing the steps of a seventh
operation method for the vacuum evacuation device of FIG. 12.
[0058] FIG. 18 is a graph showing the timeline of the seventh
operation method for the vacuum evacuation device of FIG. 12.
[0059] FIG. 19 is a chart for computing the waiting rotational
speed based on the process pressure and the gas flow.
[0060] FIG. 20 is a chart for computing the waiting rotational
speed based on the pressure reduction rate and the process chamber
capacity.
[0061] FIG. 21 is a block diagram showing the structure of a
conventional vacuum evacuation device.
[0062] FIG. 22 is a flowchart showing the steps of an operation
method for the vacuum evacuation device of FIG. 21.
[0063] FIG. 23 is a graph showing the timeline of the operation
method for the vacuum evacuation device of FIG. 21.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0064] A first embodiment of the present invention will be
hereinafter described with reference to the drawings. The same or
corresponding parts are denoted in all the drawings with the same
reference numerals, and redundant description is not repeated.
[0065] As shown in FIG. 1, a substrate processing apparatus 1
according to the first embodiment of the present invention includes
a vacuum evacuation device 2 (the part surrounded by the broken
line in the drawing), an airtight process chamber 21 in which a
process reaction is caused, and a flow rate regulator 3 for
regulating the flow rate of a process gas G1 to be introduced into
the process chamber 21. The process gas G1 may be, for example, a
nitrogen gas, a helium gas, an argon gas, an inert gas as a mixture
of these gases, a cleaning gas such as a ClF.sub.3 gas, and a
reaction gas such as a SiH.sub.2Cl.sub.2 gas.
[0066] The vacuum evacuation device 2 includes a turbo molecular
pump 4, as a first vacuum pump, connected to the process chamber 21
via exhaust piping 12 to exhaust a gas G2 from the inside of the
process chamber 21 and reduce the pressure P21 in the process
chamber 21 to a vacuum, a dry pump 5, as a second vacuum pump,
serially connected to the exhaust side of the turbo molecular pump
4 via exhaust piping 13 to exhaust the gas G2 from the exhaust side
of the turbo molecular pump 4 to the outside (to the atmosphere,
for example), and a pressure controller 6, as a control means, for
controlling the operation (startup, stop, rotational speed N4 and
N5, etc.) of the turbo molecular pump 4 and the dry pump 5 to bring
the process chamber 21 to a desired pressure condition, suitable
for the process reaction.
[0067] The turbo molecular pump 4 has a casing 4C, a pump rotor 4R
housed in the casing 4C, a turbo molecular pump motor 4M for
driving the pump rotor 4R, and a bearing (not shown) for supporting
the pump motor 4M and the pump rotor 4R for rotation. The dry pump
5 has a casing 5C, a pump rotor 5R housed in the casing 5C, a dry
pump motor 5M for driving the pump rotor 5R, and a bearing (not
shown) for supporting the pump motor 5M and the pump rotor 5R for
rotation.
[0068] The vacuum evacuation device 2 also includes a pressure
gauge 7 provided to the process chamber 21 to measure the pressure
P21 in the process chamber 21, a pressure gauge 8 provided to the
exhaust piping 13 to measure the pressure P13 on the exhaust side
of the turbo molecular pump 4, and an electromagnetic valve 9
provided on the exhaust piping 13 between the turbo molecular pump
4 and the dry pump 5. When the dry pump 5 is stopped, the
electromagnetic valve 9 closes the exhaust piping 13 to prevent the
pressure P21 in the process chamber 21, the pressure in the turbo
molecular pump 4, the pressure in the exhaust piping 12, and the
pressure P13 in the exhaust piping 13 from being abruptly released
to atmospheric pressure.
[0069] The pressure controller 6 receives a pressure control start
signal i1 to start pressure control in the process chamber 21, and
process information i2 related to process reaction in the process
chamber 21, from a process controller (not shown).
[0070] The pressure gauge 7 sends a pressure signal i3 indicating
the measured pressure P21 in the process chamber 21 to the pressure
controller 6. The pressure gauge 8 sends a pressure signal i4
indicating the measured pressure P13 on the exhaust side of the
turbo molecular pump 4 (the pressure in the exhaust piping 13) to
the pressure controller 6. The vacuum evacuation device 2 further
includes a motor control panel 10 for receiving external power E1
and outputting motor power E2 to the turbo molecular pump motor 4M,
and a motor control panel 11 for receiving external power E1 and
outputting motor power E3 to the dry pump motor 5M.
[0071] The pressure controller 6 sends a rotational speed command
signal i6 to regulate the rotational speed N4 of the turbo
molecular pump 4 to the motor control panel 10 as a control means,
and sends a rotational speed command signal i7 to regulate the
rotational speed N5 of the dry pump 5 to the motor control panel 11
as a control means. On receiving the speed command signal i6, the
motor control panel 10 regulates the motor power E2 to be supplied
to the turbo molecular pump 4 (by regulating voltage or frequency,
for example) such that the turbo molecular pump 4 rotates at the
commanded speed N4. On receiving the speed command signal i7, the
motor control panel 11 regulates the motor power E3 to be supplied
to the dry pump 5 such that the dry pump 5 rotates at the commanded
speed N5.
[0072] The process controller (not shown) sends a regulation signal
i8 to the flow rate regulator 3 to regulate the flow rate of
process gas to be introduced into the process chamber 21. The flow
rate regulator 3 regulates the flow rate of the process gas G1 to
be introduced into the process chamber 21 based on the regulation
signal i8. In the case where there is a possibility that the
pressure P13 on the exhaust side of the turbo molecular pump 4 can
reach atmospheric pressure, the pressure controller 6 sends an
open/close command signal i9 to the electromagnetic valve 9 to
close the electromagnetic valve 9.
[0073] Next, with reference to FIG. 2 and where necessary FIG. 1,
and FIG. 3 to be described later, the steps of a first operation
method for the vacuum evacuation device 2 of this embodiment are
described. The operation method described below (and also second to
seventh operation methods to be described later) is controlled by
the pressure controller 6.
[0074] Before pressure control in the process chamber 21, the turbo
molecular pump 4 and the dry pump 5 are respectively operated at
the rated rotational speed N4r and N5r (step S1), and the process
chamber 21 is at the rated pressure P21r. On receiving process
information i2 from the process controller (not shown) (step S2),
the process controller 6 computes (calculates) a waiting rotational
speed N4w (lower than the rated speed N4r) as a specified
rotational speed for the turbo molecular pump 4 (one of the pumps)
based on the received process information i2 (step S3). When the
computation is finished, the turbo molecular pump 4 is decelerated
to bring the speed N4 of the turbo molecular pump 4 to the waiting
speed N4w (step S4). The speed N5 of the dry pump 5 is not
regulated but the dry pump 5 is kept operating at the rated speed
N5r.
[0075] Then, the process gas G1 is introduced into the process
chamber 21 to cause a process reaction in the process chamber 21
(step S5). The turbo molecular pump 4 is kept decelerating (step
S6), and it is determined whether or not the speed N4 of the turbo
molecular pump 4 has reached the waiting speed N4w (step S7). If
the speed N4 of the turbo molecular pump 4 has not reached the
waiting speed N4w (if "NO" in step S7), the turbo molecular pump 4
is kept decelerating (step S6). If the speed N4 of the turbo
molecular pump 4 has reached the waiting speed N4w (if "YES" in
step S7), the turbo molecular pump 4 is kept waiting at the waiting
speed N4w (step S8).
[0076] After that, a pressure control start signal i1 to start
pressure control in the process chamber 21 is input from the
process controller (not shown) to the pressure controller 6 (step
S9). Then, pressure increasing operation is performed to bring the
pressure P21 in the process chamber 21 to a specified pressure P21a
(higher than the rated pressure P21r) (for example, 90% of the
target pressure (desired pressure) P21x). To bring the pressure P21
in the process chamber 21 to the specified pressure P21a, the turbo
molecular pump 4 is decelerated (step S11). To decrease the
rotational speed N4, the pressure controller 6 sends a rotational
speed regulation signal i6 to the motor control panel 10, which
regulates the motor power E2 such that the speed N4 of the turbo
molecular pump 4 decreases. The turbo molecular pump 4 is in this
way decelerated.
[0077] The pressure controller 6 determines whether or not the
pressure P21 in the process chamber 21 has reached the specified
pressure P21a based on the pressure signal i3 indicating the
pressure P21 in the process chamber 21 and sent from the pressure
gauge 7 (step S12). If the pressure P21 has not reached the
specified pressure P21a (if "NO" in step S12), the speed N4 of the
turbo molecular pump 4 is kept regulated, that is, the turbo
molecular pump 4 is kept decelerating (step S11). If the pressure
P21 in the process chamber 21 has reached the specified pressure.
P21a (if "YES" in step S12), pressure control is performed to bring
the pressure P21 in the process chamber 21 to the target pressure
P21x (higher than the rated pressure P21r) (step S13), along with
which the speed N4 of the turbo molecular pump 4 is regulated (step
S14), so that the turbo molecular pump 4 is decelerated.
[0078] The pressure controller 6 determines whether or not the
pressure P21 in the process chamber 21 has reached the target
pressure P21x (step S15). If the pressure P21 has not reached the
target pressure P21x (if "NO" in step S15), the regulation of the
speed N4 of the turbo molecular pump 4 is kept on (step S14). If
the pressure P21 in the process chamber 21 has reached the target
pressure P21x (if "YES" in step S15), the pressure controller 6
keeps controlling the pressure P21 in the process chamber 21 to the
target pressure P21x (step S16). After that (after the process
reaction in the process chamber 21 is finished), a pressure control
stop signal (not shown) to stop the pressure control in the process
chamber 21 is input from the process controller (not shown) to the
pressure controller 6 (step S17), and the pressure control to bring
the pressure P21 in the process chamber 21 to the target pressure
P21x is terminated (step S18).
[0079] With reference to FIG. 3, the first operation method for the
vacuum evacuation device 2 is described in view of the passage of
time. In the drawing, the horizontal axis represents time, and the
vertical axis represents pressure or rotational speed. Also in the
drawing, P21 represents the pressure in the process chamber 21, N4
the rotational speed of the turbo molecular pump 4, N5 the
rotational speed of the dry pump 5, and P13 the pressure on the
exhaust side of the turbo molecular pump 4. P2, N4, N5 and P13 are
intended to show proportional changes of the respective values over
time, but not intended to show the correct absolute values (this
also applies to FIG. 5, FIG. 7 and FIG. 9 to be described later).
FIG. 1 is also referenced when necessary.
[0080] Before time t1, the turbo molecular pump 4 and the dry pump
5 are respectively rotating at the rated rotational speed N4r and
N5r, and the pressure P21 in the process chamber 21 and the
pressure P13 on the exhaust side of the turbo molecular pump 4 are
respectively at the rated pressure P21r and P13r. At time t1,
process information i2 is input to the pressure controller 6.
Immediately after that, the turbo molecular pump 4 starts
decelerating to bring the speed N4 of the turbo molecular pump 4 to
the waiting speed N4w. The dry pump 5 is kept rotating at the rated
speed N5r and not decelerated. The pressure P13 on the exhaust side
of the turbo molecular pump 4 thus does not change and is kept at
the rated pressure P13r. Thus, in the drawing, N5 is plotted as a
line parallel to the horizontal axis, and P13 between time t1 and
time t2 is also plotted as a line parallel to the horizontal
axis.
[0081] At time t2, introduction of the process gas G1 into the
process chamber 21 is started. As the process gas G1 is introduced
and the speed N4 of the turbo molecular pump 4 decreases, the
pressure P21 in the process chamber 21 increases gradually. Also,
as the process gas G1 is introduced, the pressure P13 on the
exhaust side of the turbo molecular pump 4 increases gradually to
reach P13b at time 2'. At time t3, the speed N4 of the turbo
molecular pump 4 reaches the waiting rotational speed N4w, and the
turbo molecular pump 4 starts waiting at the waiting speed N4w.
When the speed N4 of the turbo molecular pump 4 stops decreasing,
the increase rate of the pressure P21 in the process chamber 21
becomes lower to almost zero.
[0082] At time t4, a pressure control start signal i1 is input to
the pressure controller 6, and the speed N4 of the turbo molecular
pump 4 again starts decreasing and the pressure P21 in the process
chamber 21 starts increasing to reach the specified pressure P21a.
At time t5, the pressure P21 in the process chamber 21 reaches the
specified pressure P21a (for example, 90% of the target value), and
then pressure control is started to bring the pressure P21 in the
process chamber 21 to the target pressure P21x. In the pressure
control, the turbo molecular pump 4 is decelerated so as to
regulate the pressure P21 in the process chamber 21 to the target
pressure P21x. As the turbo molecular pump 4 decelerates, the
pressure P21 in the process chamber 21 again increases.
[0083] At time t6, the pressure P21 in the process chamber 21
reaches the target pressure P21x, and the turbo molecular pump 4
stops decelerating for the moment. Still, the pressure control is
kept on to keep the pressure P21 in the process chamber 21 at the
target pressure P21x by regulating the speed N4 of the turbo
molecular pump 4. At time t7, a pressure control stop signal (not
shown) is input to the pressure controller 6, and the control of
the pressure P21 in the process chamber 21 is finished. The
pressure control is performed so as to monotonously increase the
pressure P21 in the process chamber 21 from time t5 to time t6
without hunting or the like. The pressure control is feedback
control in which the deviation between the target pressure P21x and
the measured pressure P21 in the process chamber 21 is calculated,
and the motor power E2 for the turbo molecular pump motor 4M is
regulated according to the deviation (for example, PI control or
PID control) to regulate the speed N4 of the turbo molecular pump
4.
[0084] In this first operation method, the waiting speed N4w for
the turbo molecular pump 4 is a rotational speed close to the
rotational speed to be reached at which a process condition
suitable for the process reaction can be realized in the process
chamber 21, and preferably higher than the speed to be reached by,
for example, 20 to 30%. The speed N4 of the turbo molecular pump 4
is changed not continuously from the rated speed N4r to the speed
to be reached corresponding to the target pressure P21 of the
process chamber 21, but initially from the rated speed N4r to the
waiting speed N4w. On reaching the waiting speed N4w, the
rotational speed N4 is kept waiting at the waiting speed N4w. The
waiting speed N4w is determined so as to prevent the pressure P21
from overshooting the target pressure P21x and to reduce the
pressure shift period during subsequent pressure control to bring
the pressure P21 in the process chamber 21 to the target pressure
P21x. In the case where the pressure control can be performed
smoothly and the pressure P21 can be prevented from overshooting,
the waiting at the waiting speed N4w is not necessary and a
pressure control start signal i1 may be input immediately after the
waiting speed N4w is reached to proceed to the pressure
control.
[0085] The specified pressure P21a is close to the target pressure
P21x of the process chamber 21, and slightly lower than the target
pressure P21x (for example, 80 to 95% of the target pressure P21x).
The specified pressure P21a is determined such that the pressure
P21 can monotonously increase to reach the target pressure P21x and
can be prevented from overshooting the target pressure P21x during
the pressure control to bring the pressure P21 to the target
pressure P21x performed after the turbo molecular pump 4 is
decelerated to bring the pressure P21 in the process chamber 21 to
the specified pressure P21a.
[0086] In this operation method, the turbo molecular pump 4 is
decelerated to increase the pressure P21 in the process chamber 21
from the rated pressure P21r to the specified pressure P21a (90% of
the target pressure), and the deceleration of the turbo molecular
pump 4 is stopped when the pressure P21 reaches the specified
pressure P21a. Thus, the pressure control is not performed during
that period according to the calculation of the deviation between
the target pressure P21x and the measured pressure P21 by
comparison, and regulating of the power E2 for the turbo molecular
pump motor 4M based on the deviation to regulate the speed of the
turbo molecular pump 4. In this operation method, the pressure is
increased by simply decreasing the speed N4 of the turbo molecular
pump 4, which requires a period (t5-t1) much shorter than in an
approach through control of the pressure P21.
[0087] Meanwhile, in the case where the pressure P21 is increased
by decelerating the turbo molecular pump 4 continuously until the
pressure P21 reaches the target pressure P21x, the pressure P21
will not stop increasing immediately after reaching the target
pressure P21x and will overshoot the target pressure P21x.
Therefore, in this operation method, the pressure is increased to
the specified pressure P21a (90% of the target pressure P21x) by
deceleration, and after that, controlled by regulating of the
rotational speed N4 to prevent the pressure P21 from overshooting
the target pressure P21. This combination of the rotational speed
N4 decelerating operation and the subsequent pressure control can
prevent the pressure 21 from overshooting and reduce the period
required to achieve the target pressure P21x (t6-t4).
[0088] The timing for the introduction of the process gas G1 is
determined so that overload operation of the turbo molecular pump 4
is prevented from occurring between time t1 and time t7, by
comprehensive consideration of the type of the process gas G1, flow
rate of the process gas to be introduced, changes in the pressure
P21 in the process chamber 21, speed N4 of the turbo molecular pump
4, etc. In the case where the process gas G1 is introduced at such
a large flow rate as to exceed the operating range of the turbo
molecular pump 4, the process gas G1 is preferably introduced after
the turbo molecular pump 4 reaches the waiting speed N4w.
[0089] The process information includes target pressure, target
pressure condition, flow rate of the gas (process gas) to be
introduced, type of the gas to be introduced, pressure control
period (t7-t5), etc., that contribute to suitable pressure
control.
[0090] In the case where the range of changes in the rotational
speed N4 (the difference between the rated speed N4r and the
rotational speed corresponding to the target pressure P21x) is
small, the pressure P21 in the process chamber 21 may not
necessarily be controlled to the specified pressure P21a. This can
achieve simplified control and reduce the period for that
control.
[0091] In this operation method, the pressure controller 6 computes
the waiting speed N4w for the turbo molecular pump 4 based on the
process information related to process reaction, and the turbo
molecular pump 4 is decelerated to and kept waiting at the waiting
speed N4w before pressure control to bring the pressure P21 in the
process chamber 21 to the target pressure P21x. Therefore, it is
possible to bring the pressure P21 in the process chamber 21 to a
desired pressure suitable for the process reaction in a short
period without the turbo molecular pump 4 being overloaded in the
pressure control performed by regulating the speed N4 of the turbo
molecular pump 4, regardless of the process reaction condition. In
addition, the waiting speed N4w for the turbo molecular pump 4 can
be determined and the speed N4 of the turbo molecular pump 4 can be
decreased in an appropriate manner. Therefore, the pressure P21 in
the process chamber 21 can be made to monotonously increase without
hunting to reach the target pressure P21x in a short period, and
can be prevented from overshooting the target pressure P21 during
the pressure increasing process.
[0092] In this operation method, not the speed N5 of the dry pump 5
but only the speed N4 of the turbo molecular pump 4 is regulated.
This is suitable for the case where the flow rate of the process
gas to be introduced is relatively small (for example, 5.0 SLM or
less) (SLM denotes liter/minute under standard condition) and the
difference between the rated pressure P21r of the process chamber
21 and the target pressure P21x suitable for the process reaction
is relatively small, that is, the rated pressure P21r is a high
vacuum (0.1 Torr or less) and the target pressure P21x is a
relatively high vacuum (for example, 0.5 Torr or less), resulting
in a relatively small pressure control range.
[0093] Further, when using a turbo molecular pump 4 having a
magnetic bearing (not shown) which operates in a vacuum in a
non-contacting manner, since deceleration takes time due to the
absence of friction and the pressure P21 in the process chamber 21
does not change linearly with the rotational speed N4, it is
necessary to greatly change the rotational speed N4, which prolongs
the pressure control period for the process chamber 21. In this
operation method, however, the rotational speed N4 is decreased
initially from the rated speed N4r to the waiting speed N4w, then
decreased until the pressure P21 reaches the specified pressure
P21a, and then regulated so as to bring the pressure P21 to the
target pressure P21x, and it is possible to reduce the period to
bring the rotational speed N4 from the rated speed N4r to the speed
to be reached corresponding to the target pressure P21x
(t6-t1).
[0094] Next, with reference to FIG. 4 and where necessary FIG. 1
and FIG. 5 to be described later, the steps of a second operation
method for the vacuum evacuation device 2 according to the first
embodiment of the present invention are described.
[0095] Before pressure control in the process chamber 21 by the
pressure controller 6, the turbo molecular pump 4 and the dry pump
5 are respectively operated at the rated rotational speed N4r and
N5r (step S21). On receiving process information i2 (step S22), the
process controller 6 computes a waiting rotational speed N4w (lower
than the rated speed N4r) for the turbo molecular pump 4 and a
waiting rotational speed N5w (lower than the rated speed N5r) as a
specified rotational speed for the dry pump 5 based on the received
process information i2 (step S23). When the computation is
finished, the turbo molecular pump 4 and the dry pump 5 are
decelerated to bring the speed N4 and N5 of the turbo molecular
pump 4 and the dry pump 5 to the waiting speed N4w and N5w (step
S24).
[0096] The turbo molecular pump 4 is kept decelerating (step S25A),
and it is determined whether or not the speed N4 of the turbo
molecular pump 4 has reached the waiting speed N4w (step S26A). If
the speed N4 of the turbo molecular pump 4 has not reached the
waiting speed N4w (if "NO" in step S26A), the turbo molecular pump
4 is kept decelerating (step S25A). If the speed N4 of the turbo
molecular pump 4 has reached the waiting speed N4w (if "YES" in
step S26A), the turbo molecular pump 4 is kept waiting at the
waiting speed N4w (step S27A). When the turbo molecular pump 4
reaches the waiting speed (for example, a rotational speed equal to
or lower than the lower limit at which the motor control panel 10
can recognize the turbo molecular pump as operating), the motor
control panel 10 stops supplying power E2 to the turbo molecular
pump so that the turbo molecular pump 4 is driven by inertia and
the gas G2 exhausted from the process chamber 21 to keep rotating
at a rotational speed approximately equal to the waiting speed.
[0097] On the other hand, the dry pump 5 is kept decelerating (step
S25B), and it is determined whether or not the speed N5 of the dry
pump 5 has reached the waiting speed N5w (step S26B). If the speed
N5 of the dry pump 5 has not reached the waiting speed N5w (if "NO"
in step S26B), the dry pump 5 is kept decelerating (step S25B). If
the speed N5 of the dry pump 5 has reached the waiting speed N5w
(if "YES" in step S26B), the dry pump 5 is kept waiting at the
waiting speed N5w (step S27B) After step S24, steps S25A to S27A
and steps S25B to S27B are performed concurrently with each
other.
[0098] After steps S27A and S27B, the process gas G1 is introduced
into the process chamber 21 (step S28). Then, a pressure control
start signal i1 for the process chamber 21 is input from the
process controller (not shown) to the pressure controller 6 (step
S29). The pressure P21 in the process chamber 21 is increased to a
specified pressure P21a (higher than the rated pressure P21r) (for
example, 90% of the target pressure P21x). To increase the pressure
P21, the dry pump 5 is decelerated (step S31). Therefore, the
pressure controller 6 sends a rotational speed regulation signal i7
to the motor control panel 11, which regulates the motor power E3
such that the speed N5 of the dry pump 5 decreases. The dry pump 5
is in this way decelerated.
[0099] The pressure controller 6 determines whether or not the
pressure P21 in the process chamber 21 has reached the specified
pressure P21a (step S32). If the pressure P21 has not reached the
specified value P21a (if "NO" in step S32), the dry pump 5 is kept
decelerating (step S31). If the pressure P21 in the process chamber
21 has reached the specified value P21a (if "YES" in step S32),
pressure control is performed to bring the pressure P21 in the
process chamber 21 to the target pressure (desired pressure) P21x
(higher than the rated pressure P21r) (step S33). To regulate the
speed N5 of the dry pump 5 (step S34), the pressure controller 6
sends a rotational speed regulation signal i7 to the motor control
panel 11, which regulates the motor power E3 such that the speed N5
of the dry pump 5 decreases. The dry pump 5 is in this way
decelerated further.
[0100] The pressure controller 6 determines whether or not the
pressure P21 in the process chamber 21 has reached the target value
P21x (step S35). If the pressure P21 has not reached the target
pressure P21x (if "NO" in step S35), the speed N5 of the dry pump 5
is kept regulated, that is, the dry pump 5 is kept decelerating
(step S34). If the pressure P21 in the process chamber 21 has
reached the target pressure P21x (if "YES" in step S35), the
pressure controller 6 regulates the speed N5 of the dry pump 5 such
that the pressure P21 in the process chamber 21 is kept at the
target pressure P21x (step S36). After that, a pressure control
stop signal (not shown) to stop the pressure control in the process
chamber 21 is input from the process controller (not shown) to the
pressure controller 6 (step S37), and the pressure control to bring
the pressure P21 in the process chamber 21 to the target pressure
P21x is terminated (step S38).
[0101] With reference to FIG. 5, the second operation method for
the vacuum evacuation device 2 is described in view of the passage
of time. FIG. 1 is also referenced when necessary.
[0102] Before time t1, the turbo molecular pump 4 and the dry pump
5 are respectively rotating at the rated rotational speed N4r and
N5r, and the pressure P21 in the process chamber 21 is at the rated
pressure P21r. At time t1, process information i2 is input to the
pressure controller 6. Immediately after that, the turbo molecular
pump 4 starts decelerating to bring the speed N4 of the turbo
molecular pump 4 to the waiting speed N4w, and the dry pump 5
starts decelerating to bring the speed N5 of the dry pump 5 to the
waiting speed N5w.
[0103] At time t2, as the speed N4 and N5 of the turbo molecular
pump 4 and the dry pump 5 respectively decreases, the pressure P21
in the process chamber 21 starts increasing gradually. At time t3,
the speed N5 of the dry pump 5 reaches the waiting rotational speed
N5w, and the dry pump 5 starts waiting at the waiting speed N5w. At
time t4, the speed N4 of the turbo molecular pump 4 reaches the
waiting rotational speed N4w, and the turbo molecular pump 4 starts
waiting at the waiting speed N4w.
[0104] At time t5, introduction of the process gas G1 into the
process chamber 21 is started. At time t6, a pressure control start
signal i1 is input to the pressure controller 6, and pressure
increase by decreasing the speed N5 of the dry pump 5 (one of the
pumps) is started to bring the pressure P21 to a specified pressure
P21a (for example, 90% of the target pressure P21x). At time t7,
the pressure P21 in the process chamber 21 reaches the specified
pressure P21a, and the pressure controller 6 starts controlling the
pressure P21 in the process chamber 21. That is, the dry pump 5 is
decelerated so as to bring the pressure P21 in the process chamber
21 to the target pressure P21x. As the dry pump 5 decelerates, the
increase rate of the pressure P21 in the process chamber 21
increases. At time t8, the pressure P21 in the process chamber 21
reaches the target pressure P21x. The pressure P21 in the process
chamber 21 is still kept controlled to the target pressure P21x,
and accordingly the speed N5 of the dry pump 5 is regulated to the
rotational speed corresponding to the target pressure P21x. This
(the state where the target pressure P21x is kept) is the pressure
condition in the process chamber 21 suitable for the process
reaction. At time t9, a pressure control stop signal (not shown) is
input to the pressure controller 6, and the control of the pressure
P21 in the process chamber 21 is finished. During the period
between time t7 and time t8, when the pressure control is
performed, the pressure P21 in the process chamber 21 monotonously
increases without hunting or the like.
[0105] For description of the waiting rotational speed N5w for the
dry pump 5 in this second operation method, the description of the
waiting rotational speed N4w for the turbo molecular pump 4 in the
first operation method described before is applied, with the term
"turbo molecular pump 4" replaced by the term "dry pump 5",
"rotational speed N4" by "rotational speed N5", "rated rotational
speed N4r" by "rated rotational speed N5r", and "waiting rotational
speed N4w" by "waiting rotational speed N5w".
[0106] For description of the specified pressure P21a related to
the dry pump 5 in this second operation method, the description of
the specified pressure P21a related to the turbo molecular pump 4
in the first operation method described before is applied, with the
term "turbo molecular pump 4" replaced by the term "dry pump
5".
[0107] In this second operation method, the dry pump 5 is
decelerated to increase the pressure P21 from the rated pressure
P21r to the specified pressure P21a (90% of the target pressure),
and the deceleration of the dry pump 5 is stopped when the pressure
P21 reaches the specified pressure P21a. Thus, the pressure control
is not performed during that period by regulating the speed N5 of
the dry pump 5. In this operation method, the pressure is increased
by simply decreasing the speed N5 of the dry pump 5, which requires
a period (t7-t1) much shorter than in an approach through control
of the pressure P21.
[0108] Meanwhile, in the case where the pressure P21 is increased
by decelerating the dry pump 5 continuously until the pressure P21
reaches the target pressure P21x, the pressure P21 will not stop
increasing immediately after reaching the target pressure P21x and
will overshoot the target pressure P21x. Therefore, in this
operation method, the pressure is increased to the specified
pressure P21a (90% of the target pressure P21x) by deceleration,
and after that, controlled by regulating of the rotational speed N5
to prevent the pressure P21 from overshooting the target pressure
P21. This combination of the rotational speed N5 decelerating
operation and the subsequent pressure control can prevent the
pressure 21 from overshooting and reduce the period required to
achieve the target pressure P21x (t8-t6).
[0109] The timing for the introduction of the process gas G1 is
determined so as to prevent overload operation of the turbo
molecular pump 4 and the dry pump 5 between time t1 and time t9, by
comprehensively considering the type of the process gas G1, flow
rate of the process gas to be introduced, changes in the pressure
P21 in the process chamber 21, speed N4 of the turbo molecular pump
4, speed N5 of the dry pump 5, etc. In the case of this operation
method where the process gas G1 is introduced at such a large flow
rate as to exceed the operating range of the turbo molecular pump 4
(for example, 10 SLM or more), the process gas G1 is introduced
after the turbo molecular pump 4 reaches the waiting speed N4w and
the supply of the power E2 is stopped so that the pump rotates by
inertia.
[0110] In this second operation method, the state where the target
pressure P21x is kept is the pressure condition in the process
chamber 21 suitable for the process reaction.
[0111] In this operation method, the pressure controller 6 computes
the waiting speed N4w for the turbo molecular pump 4 and the
waiting speed N5w for the dry pump 5 based on the process
information related to process reaction, and the dry pump 5 is
decelerated to and kept waiting at the waiting speed N5w before
pressure control to bring the pressure P21 in the process chamber
21 to the target pressure P21x. Therefore, it is possible to bring
the pressure P21 in the process chamber 21 to a desired pressure
suitable for the process reaction in a short period without the dry
pump 5 being overloaded in the pressure control performed by
regulating the speed N5 of the dry pump 5, regardless of the
process reaction condition. Since the turbo molecular pump 4 is
rotating at the waiting speed when the process gas G1 is
introduced, the turbo molecular pump 4 will not be overloaded.
[0112] In addition, the waiting speed N5w for the dry pump 5 can be
determined and the speed N5 of the dry pump 5 can be decreased in
an appropriate manner. Therefore, the pressure P21 in the process
chamber 21 can be made to monotonously increase without hunting to
reach the target pressure P21x in a short period, and can be
prevented from overshooting the target pressure P21 during the
pressure increasing process.
[0113] In this second operation method, not the speed N4 of the
turbo molecular pump 4 but only the speed N5 of the dry pump 5 is
regulated. This is suitable for the case where the flow rate of the
process gas introduced is relatively large (for example, 10 SLM or
more) and the difference between the rated pressure P21r of the
process chamber 21 and the target pressure P21x suitable for the
process reaction is relatively large, that is, the rated pressure
P21r is a high vacuum (0.1 Torr or less) and the target pressure
P21x is a relatively high vacuum (for example, 0.5 Torr or more),
resulting in a relatively large pressure control range.
[0114] Next, with reference to FIG. 6 and where necessary FIG. 1
and FIG. 7 to be described later, the steps of a third operation
method for the vacuum evacuation device 2 according to the first
embodiment of the present invention are described.
[0115] Before pressure reduction control in the process chamber 21
by the pressure controller 6, the atmosphere (air) is introduced
into the process chamber 21 and the process chamber 21 is at
atmospheric pressure. That is, the process chamber is once exposed
to the atmosphere and filled with air. The turbo molecular pump 4
is stationary, and the dry pump 5 is operated at the rated
rotational speed N5r (step S41). On receiving process information
i2 from the process controller (not shown) (step S42), the process
controller 6 computes a waiting rotational speed N5w for the dry
pump 5 based on the received process information i2 (step S43).
When the computation is finished, the pressure controller 6
decelerates the dry pump 5 to bring the speed N5 of the dry pump 5
to the waiting speed N5w (step S44).
[0116] Then, it is determined whether or not the speed N5 of the
dry pump 5 has reached the waiting speed N5w (step S45). If the
speed N5 of the dry pump 5 has not reached the waiting speed N5w
(if "NO" in step 45), the dry pump 5 is kept decelerating (step
S44) If the speed N5 of the dry pump 5 has reached the waiting
speed N5w (if "YES" in step S45), the dry pump 5 is kept waiting at
the waiting speed N5w (step S46).
[0117] After that, a pressure reduction control start signal (not
shown) to reduce the pressure P21 in the process chamber 21 at the
target (desired) pressure reduction rate PR21x is input from the
process controller (not shown) to the pressure controller 6 (step
S47), and pressure reduction control for the pressure P21 in the
process chamber 21 is performed by regulating the speed N5 of the
dry pump 5 (step S48). The pressure controller 6 sends a rotational
speed regulation signal i7 to the motor control panel 11, which
regulates the motor power E3 such that the speed N5 of the dry pump
5 increases. The dry pump 5 is in this way accelerated (step
S49).
[0118] While the dry pump 5 is accelerating, the pressure
controller 6 determines whether or not the speed N5 of the dry pump
5 has reached the rated speed N5r (step S50). If the speed N5 of
the dry pump 5 has not reached the rated speed N5r (if "NO" in step
S50), it is determined whether or not the pressure P21 in the
process chamber 21 is higher than a specified value P21b (step
S52). If the pressure P21 in the process chamber 21 is higher than
the specified value P21b (if "YES" in step S52), it is determined
whether the pressure reduction rate PR21 in the process chamber 21
(evacuation rate in the process chamber 21) is higher than the
target value PR21x (step S54). Whether a pressure reduction rate
(unit Torr/sec) is larger or smaller is determined by absolute
value of inclination of pressure curve. If the pressure reduction
rate PR21 in the process chamber 21 is lower than the target value
PR21x (if "NO" in step S54), the speed N5 of the dry pump 5 is
increased (step S49), and if the pressure reduction rate PR21 in
the process chamber 21 is higher than the target value PR21x (if
"YES" in step S54), the rotational speed of the dry pump 5 is
decelerated (step S55) the process returns to the point before step
S50.
[0119] If the pressure P21 in the process chamber 21 is lower than
the specified value P21b (if "NO" in step S52), it is determined
that the exhaust side pressure of the turbo molecular pump 4 has
reached the value at which the pump 4 can be started up, then the
turbo molecular pump 4 is started up (step S53).
[0120] If the speed N5 of the dry pump 5 has reached the rated
speed N5r (if "YES" in step S50), the regulation of the speed of
the dry pump 5 is stopped (step S51) to keep the dry pump 5
rotating at the rated speed N5r, and the pressure reduction control
to reduce the pressure P21 in the process chamber 21 at the target
pressure reduction rate PR21x is terminated (step S56).
[0121] The pressure reduction rate is included in the process
information i2. The capacity of the process chamber 21 is also
included in the process information i2.
[0122] With reference to FIG. 7, the third operation method for the
vacuum evacuation device 2 is described in view of the passage of
time. FIG. 1 is also referenced when necessary.
[0123] Before time t1, the turbo molecular pump 4 is stationary,
the dry pump 5 is rotating at the rated rotational speed N5r, and
the pressure P21 in the process chamber 21 is at atmospheric
pressure. At time t1, process information i2 is input to the
pressure controller 6 for slow evacuation of the process chamber
21. Immediately after that, the dry pump 5 starts decelerating to
bring the speed N5 of the dry pump 5 to the waiting speed N5w. At
time t2, the speed N5 of the dry pump 5 reaches the waiting
rotational speed N5w, and the dry pump 5 starts waiting at the
waiting speed N5w. During this period, the electromagnetic valve 9
is closed, and hence the pressure P21 in the process chamber 21 and
the pressure P13 on the exhaust side of the turbo molecular pump 4
do not change.
[0124] At time t3, a pressure reduction control start signal (not
shown) is input to the pressure controller 6, and the
electromagnetic valve 9 is opened to start control that regulates
the speed N5 of the dry pump 5 so as to bring the pressure
reduction rate PR21 (evacuation rate (in Torr/sec)) for the
pressure P21 in the process chamber 21 to the target value PR21x.
That is, the pressure reduction rate PR21 in the process chamber 21
is controlled to the constant target value PR21x by regulating the
speed N5 of the dry pump 5 so as to increase. During this period,
the pressure P13 on the exhaust side of the turbo molecular pump 4
is also reduced at an approximately constant pressure reduction
rate PR13. As the speed N5 of the dry pump 5 increases, the
pressure P21 in the process chamber 21 decreases from atmospheric
pressure and the degree of vacuum is increased.
[0125] At time t4, the pressure P21 in the process chamber 21
reaches the specified pressure P21b, and a startup signal (not
shown) is sent from the pressure controller 6 to the motor control
panel 10 to start up the turbo molecular pump 4. At time t5, the
speed N5 of the dry pump 5 reaches the rated speed N5r, and the
control to keep the pressure reduction rate PR21 in the process
chamber 21 to a constant value is terminated. The slow evacuation
operation is thus terminated. At time t6, the pressure P21 in the
process chamber 21 reaches the rated value P21r. At time t7, the
speed N4 of the turbo molecular pump 4 reaches the rated speed N4w,
and the vacuum evacuation device 2 shifts to rated operation.
[0126] The pressure controller 6 computes the waiting speed N5w for
the dry pump 5 based on the process information related to process
reaction, and the dry pump 5 is kept waiting at the waiting speed
N5w before pressure reduction control to reduce the pressure P21 in
the process chamber 21 at the target pressure reduction rate PR21x.
Therefore, it is possible to bring the pressure reduction rate PR21
in the process chamber 21 to a desired value PR21x suitable for the
process reaction in a short period without the dry pump 5 being
overloaded in the pressure reduction control performed by
regulating the speed N5 of the dry pump 5, regardless of the
process reaction condition. The waiting speed N5w for the dry pump
5 and the increase in the speed N5 of the dry pump 5 are determined
appropriately such that the pressure in the process chamber 21
monotonously decreases without hunting, thereby allowing the
pressure reduction rate PR21 in the process chamber 21 to reach the
target (desired) pressure reduction rate PR21x in a short
period.
[0127] Since the pressure reduction (evacuation) is performed at
the constant specified pressure reduction rate PR21x (evacuation
rate), it is possible to prevent particles produced in the process
chamber 21 from flying around when the process chamber 21 is
evacuated by the dry pump 5.
[0128] In this operation method, since the pressure reduction rate
is constant from the time when the pressure P21 in the process
chamber 21 is at atmospheric pressure, the speed of a dry pump 5
capable of sucking gas with a high suction pressure and at a large
flow rate is regulated. Also in this operation method, when the
process chamber 21 is at or close to atmospheric pressure, which is
out of the operating condition of the turbo molecular pump 4, the
turbo molecular pump 4 does not operate until the pressure in the
process chamber reaches a specified pressure.
[0129] In this operation method, the state where the pressure
reduces at the target pressure reduction rate PR21x is the pressure
condition in the process chamber 21 suitable for the process
reaction.
[0130] Next, with reference to FIG. 8 and where necessary FIG. 1
and FIG. 9 to be described later, the steps of a fourth operation
method for the vacuum evacuation device 2 according to an
embodiment of the present invention are described.
[0131] Before pressure control in the process chamber 21 by the
pressure controller 6, the turbo molecular pump 4 and the dry pump
5 are respectively operated at the rated rotational speed N4r and
N5r (step S61). On receiving process information i2 (step S62), the
process controller 6 computes the waiting speed N4w for the turbo
molecular pump 4 and the waiting speed N5w for the dry pump 5 based
on the received process information i2 (step S63). When the
computation is finished, the pressure controller 6 respectively
decelerates the turbo molecular pump 4 and the dry pump 5 to bring
the speed N4 and N5 of the turbo molecular pump 4 and the dry pump
5 to the waiting speed N4w and N5w (step S64).
[0132] Then, the process gas G1 is introduced into the process
chamber 21 (step S65). The turbo molecular pump 4 is kept
decelerating (step S66A), and it is determined whether or not the
speed N4 of the turbo molecular pump 4 has reached the waiting
speed N4w (step S67A). If the speed N4 of the turbo molecular pump
4 has not reached the waiting speed N4w (if "NO" in step S67A), the
turbo molecular pump 4 is kept decelerating (step S66A). If the
speed N4 of the turbo molecular pump 4 has reached the waiting
speed N4w (if "YES" in step S67A), the turbo molecular pump 4 is
kept waiting at the waiting speed N4w (step S68A)
[0133] On the other hand, the dry pump 5 is kept decelerating (step
S66B), and it is determined whether or not the speed N5 of the dry
pump 5 has reached the waiting speed N5w (step S67B). If the speed
N5 of the dry pump 5 has not reached the waiting speed N5w (if "NO"
in step S67B), the dry pump 5 is kept decelerating (step S66B). If
the speed N5 of the dry pump 5 has reached the waiting speed N5w
(if "YES" in step S67B), the dry pump 5 is kept waiting at the
waiting speed N5w (step S68B). After step 65, steps S66A to S68A
and steps S66B to S68B are performed concurrently with each
other.
[0134] After step S68A and step S68B, a pressure control start
signal i1 to bring the pressure P21 in the process chamber 21 to
the target pressure (desired pressure) P21x is input from the
process controller (not shown) to the pressure controller 6 (step
S69). The dry pump 5 is decelerated (step S70) since the pressure
P13 on the exhaust side of the turbo molecular pump 4 is reduced to
a specified pressure P13c (for example, 80% of the target pressure
P13x) by decreasing the speed N5 of the dry pump 5. It is
determined whether or not the pressure P13 on the exhaust side of
the turbo molecular pump 4 has reached the specified pressure P13c
(step S71). If the pressure P13 on the exhaust side of the turbo
molecular pump 4 has not reached the specified pressure P13c (if
"NO" in step S71), the dry pump 5 is kept decelerating (step S70).
If the pressure P13 on the exhaust side of the turbo molecular pump
4 has reached the specified pressure P13c (if "YES" in step S71),
pressure control is performed to bring the pressure P13 on the
exhaust side of the turbo molecular pump 4 to the target pressure
P13x by regulating the speed N5 of the dry pump 5 (step S72). If
the pressure P13 on the exhaust side of the turbo molecular pump 4
has reached the target pressure P13x (step S73), the speed N5 of
the dry pump 5 is further regulated and the pressure P13 on the
exhaust side of the turbo molecular pump 4 is kept controlled to
the target pressure P13x (step S74).
[0135] After a pressure control start signal i1 for the process
chamber 21 is input from the process controller (not shown) to the
pressure controller 6 (step S69), the turbo molecular pump 4 is
decelerated (step S75), and it is determined whether or not the
pressure P21 in the process chamber 21 has increased by a specified
pressure .DELTA.P21d (for example, 20 mTorr) compared to that
before the pressure control was started (step S76). If the pressure
P21 in the process chamber 21 has not increased by the specified
pressure .DELTA.P21d (if the amount of increase is less than the
specified pressure .DELTA.P21d) (if "NO" in step S76), the turbo
molecular pump 4 is kept decelerating (step S75). If the pressure
P21 in the process chamber 21 has increased by the specified
pressure .DELTA.P21d (if the amount of increase is not less than
the specified pressure .DELTA.P21d) (if "YES" in step S76), the
speed of the turbo molecular pump 4 is increased by a certain
rotational speed .DELTA.N4d (for example, 20% of the rated speed)
and the turbo molecular pump 4 is kept at the increased rotational
speed N4d (step S77).
[0136] Then, it is determined whether or not the pressure on the
exhaust side of the turbo molecular pump 4 has reached the
specified pressure P13c (for example, 80% of the target pressure
P13x) (step S78). If the specified pressure P13c has not been
reached (if less than the specified pressure P13c) (if "NO" in step
S78), the increased speed N4d is kept (step S77). If the specified
pressure P13c has been reached (if not less than the specified
pressure P13c) (if "YES" in step S78), the turbo molecular pump 4
is decelerated to reduce the pressure P21 in the process chamber 21
to the specified pressure P21a (for example, 90% of the target
pressure P21x) (step S79).
[0137] It is determined whether or not the pressure in the process
chamber 21 has reached the specified pressure P21a (step S80). If
the specified pressure P21a has not been reached (if "NO" in step
S80), the turbo molecular pump 4 is kept decelerating (step S79).
If the specified pressure P21a has been reached (if "YES" in step
S80), pressure control is performed to bring the pressure P21 in
the process chamber 21 to the target pressure by regulating the
speed N4 of the turbo molecular pump 4 (step S81). When the
pressure P21 in the process chamber 21 reaches the target pressure
P21x (step S82), the speed N4 of the turbo molecular pump 4 and the
pressure P21 in the process chamber 21 is kept controlled to the
target pressure P21x (step S83). After step S74 and step S83, a
pressure control stop signal (not shown) to stop the pressure
control in the process chamber 21 is input from the process
controller (not shown) to the pressure controller 6 (step S84), and
the pressure control for the pressure P21 in the process chamber 21
is terminated (step S85).
[0138] After step S69, steps S70 to S74 and steps S75 to S83 are
performed concurrently with each other as two control systems.
[0139] With reference to FIG. 9, the fourth operation method for
the vacuum evacuation device 2 is described in view of the passage
of time. FIG. 1 is also referenced when necessary.
[0140] Before time t1, the turbo molecular pump 4 and the dry pump
5 are respectively rotating at the rated rotational speed N4r and
N5r, and the pressure P21 in the process chamber 21 is at the rated
value P21r. At time t1, process information i2 is input to the
pressure controller 6. Immediately after that, the turbo molecular
pump 4 and the dry pump 5 respectively start decelerating to bring
the speed N4 and N5 of the turbo molecular pump 5 and the dry pump
5 to the waiting speed N4w and N5w.
[0141] At time t2, introduction of the process gas G1 into the
process chamber 21 is started. As the process gas G1 is introduced
and subsequently the speed N4 and N5 of the turbo molecular pump 4
and the dry pump 5 decreases, the pressure P21 in the process
chamber 21 increases gradually.
[0142] At time t3, the speed N5 of the dry pump 5 reaches the
waiting rotational speed N5w, after which the dry pump 5 waits at
the waiting speed N5w. At time t4, the speed N4 of the turbo
molecular pump 4 reaches the waiting rotational speed N4w, after
which the turbo molecular pump 4 waits at the waiting speed
N4w.
[0143] At time t5, a pressure control start signal i1 is input to
the pressure controller 6. After that, the speed N4 of the turbo
molecular pump 4 again starts decreasing so as to start pressure
increasing operation to bring the pressure P13 on the exhaust side
of the turbo molecular pump 4 to the specified pressure P13c (for
example, 80% of the target pressure P13x). The speed N5 of the dry
pump 5 is also decreased so that the pressure P21 in the process
chamber 21 starts increasing.
[0144] At time t6, when the pressure P21 in the process chamber 21
auhas increased by the specified pressure .DELTA.P 21d (for
example, 20 mTorr) from that before the pressure control start
signal i1 was input and the turbo molecular pump 4 started
decelerating, the speed of the turbo molecular pump 4 increases by
a certain rotational speed .DELTA.N4d (for example, 20% of the
rated speed) and is kept at the increased speed N4d (for example,
the current rotational speed plus 20% of the rated speed).
[0145] At time t7, the pressure P13 on the exhaust side of the
turbo molecular pump 4 reaches the specified pressure P13c, and
pressure control is performed to bring the pressure P13 on the
exhaust side to the target pressure P13x by regulating the speed N5
of the dry pump 5. Also, pressure reduction operation is performed
to bring the pressure P21 in the process chamber 21 to the
specified pressure P21a ((for example, 90% of the target pressure
P21x) by regulating the speed N4 of the turbo molecular pump 4.
[0146] At time t8, the pressure P13 on the exhaust side of the
turbo molecular pump 4 reaches the target pressure P13x. After
that, the pressure control is kept on to keep the pressure P13 on
the exhaust side of the turbo molecular pump 4 at the target value
P13x.
[0147] At time t9, the pressure P21 in the process chamber 21
reaches the specified pressure P21a, and pressure control is
started to bring the pressure P21 in the process chamber 21 to the
target pressure P21x by regulating the speed N4 of the turbo
molecular pump 4. At time t10, the pressure P21 in the process
chamber 21 reaches the target pressure P21x, and the pressure
control is kept on to keep the pressure P21 in the process chamber
21 at the target pressure P21x.
[0148] At time t11, a pressure control stop signal (not shown) is
input to the pressure controller 6, and the pressure control for
the pressure P21 in the process chamber 21 and the pressure control
for the pressure P13 on the exhaust side of the turbo molecular
pump 4 are finished.
[0149] In this operation method, the pressure controller 6 computes
the waiting speed N4w and N5w for the turbo molecular pump 4 and
the dry pump 5 based on the process information related to process
reaction, and the turbo molecular pump 4 is kept waiting at the
waiting speed N4w before pressure control to bring the pressure P21
in the process chamber 21 to the target pressure P21x while the dry
pump 5 is kept waiting at the waiting speed N5w before pressure
control to bring the pressure P13 on the exhaust side of the turbo
molecular pump 4 to the target pressure P13x. Therefore, it is
possible to bring the pressure P21 in the process chamber 21 to a
desired pressure P21x suitable for the process reaction in a short
period without the turbo molecular pump 4 and the dry pump 5 being
overloaded in the pressure control performed by regulating the
speed N4 of the turbo molecular pump 4 and the pressure control
performed by regulating the speed N5 of the dry pump N5, regardless
of the process reaction condition. In addition, the waiting speed
N4w and N5w for the turbo molecular pump 4 and the dry pump 5 can
be determined and the speed N4 and N5 of the turbo molecular pump 4
and the dry pump 5 can be decreased in an appropriate manner.
Therefore, the pressure P21 in the process chamber 21 can be made
to monotonously decrease without hunting to reach the target
pressure P21x in a short period.
[0150] This operation method controls the pressure P21 in the
process chamber 21 and the pressure P13 on the exhaust side of the
turbo molecular pump 4 by regulating both the speed N4 and N5 of
the turbo molecular pump 4 and the dry pump 5. Therefore, it is
possible to perform appropriate pressure control over a wider
pressure range (in the case with a large difference between the
target pressure and the rated pressure). This operation method is
suitable for the case with such a large flow rate of the process
gas G1 as to be exhausted not solely by the dry pump 5 but by using
the turbo molecular pump 4 and the dry pump 5 in combination.
[0151] In this operation method, after both the turbo molecular
pump 4 and the dry pump 5 are kept waiting at the appropriate
waiting speed N4w and N5w, the pressure P21 in the process chamber
21 is controlled by regulating the speed of the turbo molecular
pump 4, and the pressure P13 on the exhaust side of the turbo
molecular pump 4 is controlled by regulating the speed N5 of the
dry pump 5. The pressure control for the pressure P21 is started
after the pressure P13 reaches the target pressure P13x in the
pressure control for the pressure P13. Thus, in the case where the
pressure control for the pressure P21 and the pressure control for
the pressure P13 are started at the same time, if the pressure P21
reaches the target pressure P21x before the pressure P13 reaches
the target pressure P13x, the pressure P21 in the process chamber
21 may overshoot due to variations in the pressure P13, which is
the exhaust pressure of the turbo molecular pump 4. This operation
method can avoid such a problem.
[0152] If the pressure P21 in the process chamber 21 reaches the
target pressure P21x before the pressure P13 on the exhaust side of
the turbo molecular pump 4 reaches the target pressure P13x, the
speed N4 of the turbo molecular pump 4 is kept at the speed at
which the target pressure P21x was reached, and regulated only
minutely. On the other hand, if the pressure P13 on the exhaust
side of the turbo molecular pump 4 has not reached the target
pressure P13x, the dry pump 5 is decelerated. As the dry pump 5
decelerates, the pressure P13 on the exhaust side of the turbo
molecular pump 4 increases. When the pressure P13 on the exhaust
side of the turbo molecular pump 4 increases, it is necessary to
increase the speed of the turbo molecular pump 4 in order to keep
the pressure P21 in the process chamber 21 constant, even with a
constant gas flow rate. This is because the exhaust performance
decreases as the pressure P13 on the exhaust side increases, even
with the same rotational speed. Therefore, if the pressure P13 on
the exhaust side of the turbo molecular pump 4 increases due to
deceleration of the dry pump 5 when the turbo molecular pump 4 is
operated at an approximately constant rotational speed, the speed
N4 of the turbo molecular pump 4 must be increased. With a gas
flowing, the turbo molecular pump 4 takes more time to increase its
speed than with no load, and hence cannot increase its speed enough
to follow the increase in the pressure P13 on the exhaust side due
to the deceleration of the dry pump 5, resulting in the pressure
P21 in the process chamber 21 being increased. In other words, the
increase of the pressure P21 in the process chamber 21 lends
overshooting. In this operation method, the pressure P21 reaches
the target pressure P21x after the pressure P13 on the exhaust side
reaches the target pressure P13x, thereby preventing the pressure
P21 from overshooting.
[0153] In this operation method, in decreasing the speed N4 and N5
of the turbo molecular pump 4 and the dry pump 5 to increase the
pressure P21 in the process chamber 21 after the turbo molecular
pump 4 and the dry pump 5 are kept waiting at the waiting speed N4w
and N5w, when the pressure in the process chamber 21 is increased
by the specified value .DELTA.P21d (20 mTorr in the above
description) or more, the speed N4 of the turbo molecular pump 4 is
increased by the certain rotational speed .DELTA.N4d. This is
intended to prevent the pressure P21 in the process chamber 21 from
overshooting by slightly increasing the speed of the turbo
molecular pump 4 when the pressure P21 in the process chamber 21
has started increasing, so that the pressure P13 on the exhaust
side of the turbo molecular pump 4, which increases as the pressure
P21 in the process chamber 21 increases, does not influence the
pressure P21 in the process chamber 21.
[0154] In this operation method, the state where the target
pressure P21x is kept is the desired pressure condition in the
process chamber 21 suitable for the process reaction. Also, the
state where the target pressure P13x is kept is the desired
pressure condition on the exhaust side of the turbo molecular pump
4.
[0155] With reference to FIG. 10, and where appropriate, FIG. 1,
FIG. 3, FIG. 5, FIG. 7 and FIG. 9, the structure of the process
chamber 21 of the vacuum evacuation device 1 of FIG. 1 is described
in detail. FIG. 10 is a detailed block sectional view showing the
structure of the process chamber 21.
[0156] The process chamber 21 is a vertical chamber for processing
where a heat treatment is performed, for example a quartz reaction
tube 21 for receiving an object to be processed, for example a
semiconductor wafer w, to serve as a heat treatment furnace where a
specified process, for example CVD process, is performed. While the
reaction tube 21 in the illustrated example is of a double tube
structure with an inner tube 32a and an outer tube 32b, the
reaction tube 21 may be of a single tube structure (not shown) with
only an outer tube 32b. To the lower part of the reaction tube 21
is connected in an air-tight manner an annular manifold 45 having a
gas inlet pipe part (gas inlet port) 33 for introducing a gas for
processing and an inert gas for purging into the reaction tube 21,
and an exhaust pipe part (exhaust port) 34 for evacuating the
reaction tube 21.
[0157] Piping 37 having a flow rate regulator 3 (FIG. 1) installed
thereon and for supplying the process gas G1 is connected to the
gas inlet pipe part 33, and exhaust piping 12 for communicating the
reaction tube 21 with the turbo molecular pump 4 capable of
pressure reduction control is connected to the exhaust pipe part
34. The manifold 45 is attached to a base plate (not shown). A
cylindrical heater 46 capable of heating the reaction tube 21 to a
specified temperature, for example 300 to 1200.degree. C., is
provided around the reaction tube 21.
[0158] The manifold 45 at the lower end of the reaction tube 21
forms an entrance 40 to the heat treatment furnace, and a lid 41
for opening and closing the furnace entrance 40 is provided below
the heat treatment furnace so as to be ascended and descended by an
elevating mechanism 42. The lid 41 can contact the opening end of
the manifold 45 to tightly close the furnace entrance 40.
[0159] On the lid 41 is placed, via a heat retaining tube 44 as a
furnace entrance thermally insulating means, a heat treatment boat
43 for supporting a plurality of, for example about 25 to 150,
wafers w horizontally and spaced vertically in layers. The boat 43
is loaded (inserted) into the reaction tube 21 as the lid 41
ascends by the elevating mechanism 42, and unloaded (taken out)
from the reaction tube 21 as the lid 41 descends.
[0160] Next, the function and processing method of the thus
constructed process chamber 21 is described. First of all, the heat
treatment boat 43 with the wafers w mounted thereon is inserted
into the reaction tube 21, together with the heat retaining tube
44, while an inert gas as the process gas G1, for example a
nitrogen gas, is introduced into the reaction tube 21 through the
flow rate regulator 3.
[0161] Then, the reaction tube 21 is evacuated for vacuum
replacement (initial evacuation) via the exhaust piping 12 by the
turbo molecular pump 4 and the dry pump 5, with a shut-off valve
(not shown) installed in the upstream of the flow rate regulator 3
shut. At this time, the third operation method described before is
used to prevent particles from flying up.
[0162] After the vacuum replacement, a gas for processing as the
process gas is introduced into the reaction tube 21 via the flow
rate regulator 3, and a specified process, for example a process to
form a film on the wafer is started. The process to be performed at
this time may be a film forming process, such as TEOS process, to
cause a reaction by-product which is hard at normal temperatures,
for example silicon dioxide (SiO.sub.2), to be deposited on a part
where the pressure varies.
[0163] After the film forming process, vacuum replacement and
nitrogen gas replacement may be performed in the reaction tube 21,
and then either the next process is performed or terminated by
bringing the reaction tube 21 back to normal pressures and taking
out the heat treatment boat 43 from the reaction tube 21 after the
vacuum replacement and the nitrogen gas replacement.
[0164] In the initial evacuation described before, continuously
variable control at evacuation rates of 0.1 to 20 Torr/second is
possible, and when performed optimally, can prevent particles or
the like from flying up and accomplish the process in a minimum
period to reduce the time required.
[0165] In addition, a low vacuum process is possible. For example,
a cleaning gas can be introduced into the reaction tube 21 via the
flow rate regulator 3, with the pressure in the reaction tube 21
reduced to a low vacuum (slightly reduced pressure) of about
several hundred Torr by regulating of the rotational speed of the
turbo molecular pump 4 and the dry pump 5, in order to clean the
inside of the reaction tube 21. Plural types of processes using
different types of gases and processing pressures can be performed
in any of the first, second and fourth operation methods described
above, and such plural types of processes can be performed
successively.
[0166] FIG. 11 shows pressure changes in the process chamber 21
over time in the third operation method of the present invention by
the curved line A. The curved line B shows pressure changes in the
case with the pressure reduction rate regulated by regulating the
opening degree of a pressure regulating valve (not shown) provided
on an intermediate portion of the flow path and without the
rotational speed of the dry pump being regulated after the dry pump
is started up. The vertical axis represents pressure (in Torr), and
the horizontal axis represents time. In the drawing, the dry pump 5
starts decelerating at time t1, and the turbo molecular pump 4 and
the dry pump 5 respectively reach the rated speed at time t2 and t3
to start normal operation. The period from time t1 to time t2 on
the curved line A is 1.1 minutes, and the period from time t1 to
time t3 on the curved line B is 6.17 minutes. Thus, the third
operation method can save 5.07 minutes.
[0167] While the above description focuses on a vacuum evacuation
device having a process chamber 21, which is a chamber for
processing to serve as a heat treatment furnace for CVD process,
for example a crystal reaction tube 21, the present invention is
also applicable to a pressure reduction oxidation device (one type
of vacuum evacuation device) having a process chamber 21 into which
oxygen O.sub.2 and hydrogen H.sub.2 are directly introduced to form
an oxide film on a substrate.
[0168] A second embodiment of the present invention will be
hereinafter described with reference to the drawings. The same or
corresponding parts are denoted in all the drawings with the same
reference numerals, and redundant description is not repeated.
[0169] As shown in FIG. 12, a substrate processing apparatus 1
according to the second embodiment of the present invention
includes a vacuum evacuation device 2 (the part surrounded by the
broken line in the drawing), an airtight process chamber 21 in
which a process reaction is caused, and a flow rate regulator 3 for
regulating the flow rate of a process gas G1 to be introduced into
the process chamber 21. The process gas G1 may be, for example, a
nitrogen gas, a helium gas, an argon gas, an inert gas as a mixture
of these gases, a cleaning gas such as a ClF.sub.3 gas, and a
reaction gas such as a SiH.sub.2Cl.sub.2 gas.
[0170] The vacuum evacuation device 2 includes a booster dry pump
24 (rotational speed N24) (booster pump 24 hereafter), as a first
vacuum pump, connected to the process chamber 21 via exhaust piping
12 to exhaust a gas G2 from the inside of the process chamber 21
and reduce the pressure P21 in the process chamber 21 to a vacuum,
a main dry pump 25 (rotational speed N25) (main pump 25 hereafter),
as a second vacuum pump, serially connected to the exhaust side of
the booster pump 24 via an exhaust piping (not shown) to exhaust
the gas G2 from the exhaust side of the booster pump 24 to the
outside (to the atmosphere, for example), and a pressure controller
6, as a control means, for controlling the operation (startup,
stop, rotational speed N24 and N25, etc.) of the booster pump 24
and the main pump 25 to bring the process chamber 21 to a desired
pressure condition, suitable for the process reaction. In this
embodiment of the present invention, as described before, both the
first vacuum pump and the second vacuum pump are dry pumps.
[0171] The booster pump 24 has a casing 24C, a pump rotor 24R
housed in the casing 24C, a booster pump motor 24M for driving the
pump rotor 24R, and a bearing (not shown) for supporting the pump
motor 24M and the pump rotor 24R for rotation. The main pump 25 has
a casing 25C, a pump rotor 25R housed in the casing 25C, a main
pump motor 25M for driving the pump rotor 25R, and a bearing (not
shown) for supporting the pump motor 25M and the pump rotor 25R for
rotation.
[0172] The vacuum evacuation device 2 also includes a pressure
gauge 7 provided to the process chamber 21 to measure the pressure
P21 in the process chamber 21, and an electromagnetic valve 9
provided on the exhaust piping 12 between the process chamber 21
and the booster pump 24. When the main pump 25 is stopped, the
electromagnetic valve 9 closes the exhaust piping 12 to prevent the
pressure P21 in the process chamber 21 from being abruptly released
to atmospheric pressure.
[0173] The pressure controller 6 receives a pressure control start
signal i1 to start pressure control in the process chamber 21, and
process information i2 related to process reaction in the process
chamber 21, from a process controller (not shown).
[0174] The pressure gauge 7 sends a pressure signal i3 indicating
the measured pressure P21 in the process chamber 21 to the pressure
controller 6. The vacuum evacuation device 2 includes a motor
control panel 31 for receiving external power E1, outputting motor
power E3 to the main pump motor 25M, and outputting motor power E2
to the booster pump motor 24M. A motor panel may be provide for the
booster pump 24 and the main pump 25 respectively.
[0175] The pressure controller 6 sends a rotational speed command
signal i10 to regulate the rotational speed N25 of the main pump 25
and the rotational speed N24 of the booster pump 24 to the motor
control panel 31 as a control means. On receiving the speed command
signal i10, the motor control panel 31 regulates the motor power E3
to be supplied to the main pump 25 (by regulating voltage or
frequency, for example) such that the main pump 25 rotates at the
commanded speed N25. On receiving the speed command signal i10, the
motor control panel 13 regulates the motor power E2 to be supplied
to the booster pump 24 such that the booster pump 24 rotates at the
commanded speed N24.
[0176] The process controller (not shown) sends a regulation signal
i8 to the flow rate regulator 3 to regulate the flow rate of
process gas to be introduced into the process chamber 21. The flow
rate regulator 3 regulates the flow rate of the process gas G1 to
be introduced into the process chamber 21 based on the regulation
signal i8. In the case where there is a possibility that the
pressure P21 of the process chamber can reach atmospheric pressure,
the pressure controller 6 sends an open/close command signal i9 to
the electromagnetic valve 9 to close the electromagnetic valve
9.
[0177] Next, with reference to FIG. 13 and where necessary FIG. 12,
and FIG. 14 to be described later, the steps of a fifth operation
method for the vacuum evacuation device 2 of this embodiment are
described. The operation method described below is controlled by
the pressure controller 6.
[0178] Before pressure control in the process chamber 21, the main
pump 25 and the booster pump 24 are respectively operated at the
rated rotational speed N24r and N25r (step S201), and the process
chamber 21 is at the rated pressure P21r. On receiving process
information i2 from the process controller (not shown) (step S202),
the process controller 6 computes (calculates) a waiting rotational
speed N24w (lower than the rated speed N24r) as a specified
rotational speed for the booster pump 24 (one of the pumps) based
on the received process information i2 (step S203). When the
computation is finished, the booster pump 24 is decelerated to
bring the speed N24 of the booster pump 24 to the waiting speed
N24w (step S204). The speed N25 of the main pump 25 is not
regulated but the main pump 25 is kept operating at the rated speed
N25r.
[0179] Then, the process gas G1 is introduced into the process
chamber 21 to cause a process reaction in the process chamber 21
(step S205). The booster pump 24 is kept decelerating (step S206),
and it is determined whether or not the speed N24 of the booster
pump 24 has reached the waiting speed N24w (step S207). If the
speed N24 of the booster pump 24 has not reached the waiting speed
N24w (if "NO" in step S207), the booster pump 24 is kept
decelerating (step S206). If the speed N24 of the booster pump 24
has reached the waiting speed N24w (if "YES" in step S207), the
booster pump 24 is kept waiting at the waiting speed N24w (step
S208).
[0180] After that, a pressure control start signal i1 to start
pressure control in the process chamber 21 is input from the
process controller (not shown) to the pressure controller 6 (step
S209). Then, pressure increasing operation is performed to bring
the pressure P21 in the process chamber 21 to a specified pressure
P21a (higher than the rated pressure P21r) (for example, 90% of the
target pressure P21x). To bring the pressure P21 in the process
chamber 21 to the specified pressure P21a, the booster pump 24 is
decelerated (step S211). To decrease the rotational speed N24, the
pressure controller 6 sends a rotational speed regulation signal
i10 to the motor control panel 31, which regulates the motor power
E2 such that the speed N24 of the booster pump 24 decreases. The
booster pump 24 is in this way decelerated.
[0181] The pressure controller 6 determines whether or not the
pressure P21 in the process chamber 21 has reached the specified
pressure P21a based on the pressure signal i3 indicating the
pressure P21 in the process chamber 21 and sent from the pressure
gauge 7 (step S212). If the pressure P21 has not reached the
specified pressure P21a (if "NO" in step S212), the speed N24 of
the booster pump 24 is kept regulated, that is, the booster pump 24
is kept decelerating (step S211). If the pressure P21 in the
process chamber 21 has reached the specified pressure P21a (if
"YES" in step S212), pressure control is performed to bring the
pressure P21 in the process chamber 21 to the target pressure P21x
(higher than the rated pressure P21r) (step S213), along with which
the speed N24 of the booster pump 24 is regulated (step S214), so
that the booster pump 24 is decelerated.
[0182] The pressure controller 6 determines whether or not the
pressure P21 in the process chamber 21 has reached the target
pressure P21x (step S215). If the pressure P21 has not reached the
target pressure P21x (if "NO" in step S215), the regulation of the
speed N24 of the booster pump 24 is kept on (step S214). If the
pressure P21 in the process chamber 21 has reached the target
pressure P21x (if "YES" in step S215), the pressure controller 6
keeps controlling the pressure P21 in the process chamber 21 to the
target pressure P21x (step S216). Then (after the process reaction
in the process chamber 21 is finished), a pressure control stop
signal (not shown) to stop the pressure control in the process
chamber 21 is input from the process controller (not shown) to the
pressure controller 6 (step S217), and the pressure control to
bring the pressure P21 in the process chamber 21 to the target
pressure P21x is terminated (step S218).
[0183] With reference to FIG. 14, the fifth operation method for
the vacuum evacuation device 2 is described in view of the passage
of time. In the drawing, the horizontal axis represents time, and
the vertical axis represents pressure or rotational speed. Also in
the drawing, P21 represents the pressure in the process chamber 21,
N24 the rotational speed of the booster pump 24, and N25 the
rotational speed of the main pump 25. P21, N24 and N25 are intended
to show proportional changes of the respective values over time,
but not intended to show the correct absolute values (this also
applies to FIG. 16 and FIG. 18 to be described later). FIG. 12 is
also referenced when necessary.
[0184] Before time t1, the booster pump 24 and the main pump 25 are
respectively rotating at the rated rotational speed N24r and N25r,
and the pressure P21 in the process chamber 21 is at the rated
pressure P21r. At time t1, process information i2 is input to the
pressure controller 6. Immediately after that, the booster pump 24
starts decelerating to bring the speed N24 of the booster pump 24
to the waiting speed N24w. The main pump 25 is kept rotating at the
rated speed N25r and not decelerated. The pressure P13 on the
exhaust side of the booster pump 24 thus does not change and is
kept at the rated pressure P13r. Thus, in FIG. 14, N25 is plotted
as a line parallel to the horizontal axis, and P13 between time t1
and time t2 is also plotted as a line parallel to the horizontal
axis.
[0185] At time t2, introduction of the process gas G1 into the
process chamber 21 is started. As the process gas G1 is introduced
and the speed N24 of the booster pump 24 decreases, the pressure
P21 in the process chamber 21 increases gradually. At time t3, the
speed N24 of the booster pump 24 reaches the waiting rotational
speed N24w, and the booster pump 24 starts waiting at the waiting
speed N24w. When the speed N24 of the booster pump 24 stops
decreasing, the increase rate of the pressure P21 in the process
chamber 21 becomes lower to almost zero.
[0186] At time t4, a pressure control start signal i1 is input to
the pressure controller 6, and the speed N24 of the booster pump 24
again starts decreasing and the pressure P21 in the process chamber
21 starts increasing to reach the specified pressure P21a. At time
t5, the pressure P21 in the process chamber 21 reaches the
specified pressure P21a (for example, 90% of the target value), and
then pressure control is started to bring the pressure P21 in the
process chamber 21 to the target pressure P21x. In the pressure
control, the booster pump 24 is decelerated so as to regulate the
pressure P21 in the process chamber 21 to the target pressure P21x.
As the booster pump 24 decelerates, the pressure P21 in the process
chamber 21 again increases.
[0187] At time t6, the pressure P21 in the process chamber 21
reaches the target pressure P21x, and the booster pump 24 stops
decelerating for the moment. Still, the pressure control is kept on
to keep the pressure P21 in the process chamber 21 at the target
pressure P21x by regulating the speed N24 of the booster pump 24.
At time t7, a pressure control stop signal (not shown) is input to
the pressure controller 6, and the control of the pressure P21 in
the process chamber 21 is finished. The pressure control is
performed so as to monotonously increase the pressure P21 in the
process chamber 21 from time t5 to time t6 without hunting or the
like. The pressure control is feedback control in which the
deviation between the target pressure P21x and the measured
pressure P21 in the process chamber 21 is calculated, and the motor
power E2 for the booster pump motor 4M is regulated according to
the deviation (for example, PI control or PID control) to regulate
the speed N24 of the booster pump 24.
[0188] In this fifth operation method, the waiting speed N24w for
the booster pump 24 is a rotational speed close to the rotational
speed to be reached at which a process condition suitable for the
process reaction can be realized in the process chamber 21, and
preferably higher than the speed to be reached by, for example, 20
to 30%. The speed N24 of the booster pump 24 is changed not
continuously from the rated speed N24r to the speed to be reached
corresponding to the target pressure P21 of the process chamber 21,
but initially from the rated speed N24r to the waiting speed N24w.
On reaching the waiting speed N24w, the rotational speed N24 is
kept waiting at the waiting speed N24w. The waiting speed N24w is
determined so as to prevent the pressure P21 from overshooting the
target pressure P21x and to reduce the pressure shift period during
subsequent pressure control to bring the pressure P21 in the
process chamber 21 to the target pressure P21x. In the case where
the pressure control can be performed smoothly and the pressure P21
can be prevented from overshooting, the waiting at the waiting
speed N24w is not necessary and a pressure control start signal i1
may be input immediately after the waiting speed N24w is reached to
proceed to the pressure control.
[0189] The specified pressure P21a is close to the target pressure
P21x of the process chamber 21, and slightly lower than the target
pressure P21x (for example, 80 to 95% of the target pressure P21x).
The specified pressure P21a is determined such that the pressure
P21 can monotonously increase to reach the target pressure P21x and
can be prevented from overshooting the target pressure P21x during
the pressure control to bring the pressure P21 to the target
pressure P21x performed after the booster pump 24 is decelerated to
bring the pressure P21 in the process chamber 21 to the specified
pressure P21a.
[0190] In this operation method, the booster pump 24 is decelerated
to increase the pressure P21 in the process chamber 21 from the
rated pressure P21r to the specified pressure P21a (90% of the
target pressure), and the deceleration of the booster pump 24 is
stopped when the pressure P21 reaches the specified pressure P21a.
Thus, the pressure control is not performed during that period
according to the calculation of the deviation between the target
pressure P21x and the measured pressure P21 by comparison, and
regulating of the power E2 for the booster pump motor 24M based on
the deviation to regulate the speed of the booster pump. In this
operation method, the pressure is increased by simply decreasing
the speed N24 of the booster pump 24, which requires a period
(t5-t1) much shorter than in an approach through control of the
pressure P21.
[0191] Meanwhile, in the case where the pressure P21 is increased
by decelerating the booster pump 24 continuously until the pressure
P21 reaches the target pressure P21x, the pressure P21 will not
stop increasing immediately after reaching the target pressure P21x
and will overshoot the target pressure P21x. Therefore, in this
operation method, the pressure is increased to the specified
pressure P21a (90% of the target pressure P21x) by deceleration,
and then, controlled by regulating of the rotational speed N24 to
prevent the pressure P21 from overshooting the target pressure P21.
This combination of the rotational speed N24 decelerating operation
and the subsequent pressure control can prevent the pressure 21
from overshooting and reduce the period required to achieve the
target pressure P21x (t6-t4).
[0192] The timing for the introduction of the process gas G1 is
determined so that overload operation of the booster pump 24 is
prevented from occurring between time t1 and time t7, by
comprehensive consideration of the type of the process gas G1, flow
rate of the process gas to be introduced, changes in the pressure
P21 in the process chamber 21, speed N24 of the booster pump 24,
etc. In the case where the process gas G1 is introduced at such a
large flow rate as to exceed the operating range of the booster
pump 24, the process gas G1 is preferably introduced after the
booster pump 24 reaches the waiting speed N24w.
[0193] The process information includes target pressure, target
pressure condition, flow rate of the gas (process gas) to be
introduced, type of the gas to be introduced, pressure control
period (t7-t5), etc., that contribute to suitable pressure
control.
[0194] In the case where the range of changes in the rotational
speed N24 (the difference between the rated speed N24r and the
rotational speed corresponding to the target pressure P21x) is
small, the pressure P21 in the process chamber 21 may not
necessarily be controlled to the specified pressure P21a. This can
achieve simplified control and reduce the period for that
control.
[0195] In this operation method, the pressure controller 6 computes
the waiting speed N24w for the booster pump 24 based on the process
information related to process reaction, and the booster pump 24 is
decelerated to and kept waiting at the waiting speed N24w before
pressure control to bring the pressure P21 in the process chamber
21 to the target pressure P21x. Therefore, it is possible to bring
the pressure P21 in the process chamber 21 to a desired pressure
suitable for the process reaction in a short period without the
booster pump 24 being overloaded in the pressure control performed
by regulating the speed N24 of the booster pump 24, regardless of
the process reaction condition. In addition, the waiting speed N24w
for the booster pump 24 can be determined and the speed N24 of the
booster pump 24 can be decreased in an appropriate manner.
Therefore, the pressure P21 in the process chamber 21 can be made
to monotonously increase without hunting to reach the target
pressure P21x in a short period, and can be prevented from
overshooting the target pressure P21 during the pressure increasing
process.
[0196] In this operation method, not the speed N25 of the main pump
25 but only the speed N24 of the booster pump 24 is regulated. This
is suitable for the case where the flow rate of the process gas to
be introduced is relatively small (for example, 5.0 SLM or less)
(SLM denotes liter/minute under standard condition) and the
difference between the rated pressure P21r of the process chamber
21 and the target pressure P21x suitable for the process reaction
is relatively small, that is, the rated pressure P21r is a high
vacuum (0.1 Torr or less) and the target pressure P21x is a
relatively high vacuum (for example, 0.5 Torr or less), resulting
in a relatively small pressure control range.
[0197] In this operation method, however, the rotational speed N24
is decreased initially from the rated speed N24r to the waiting
speed N24w, then decreased until the pressure P21 reaches the
specified pressure P21a, and then regulated so as to bring the
pressure P21 to the target pressure P21x, and it is possible to
reduce the period to bring the rotational speed N24 from the rated
speed N24r to the speed to be reached corresponding to the target
pressure P21x (t6-t1).
[0198] Next, with reference to FIG. 15 and where necessary FIG. 12
and FIG. 16 to be described later, the steps of a sixth operation
method for the vacuum evacuation device 2 according to the second
embodiment of the present invention are described.
[0199] Before pressure control in the process chamber 21 by the
pressure controller 6, the booster pump 24 and the main pump 25 are
respectively operated at the rated rotational speed N24r and N25r
(step S221). On receiving process information i2 (step S222), the
process controller 6 computes a waiting rotational speed N24w
(lower than the rated speed N24r) for the booster pump 24 and a
waiting rotational speed N25w (lower than the rated speed N25r) as
a specified rotational speed for the main pump 25 based on the
received process information i2 (step S223). When the computation
is finished, the booster pump 24 and the main pump 25 are
decelerated to bring the speed N24 and N25 of the booster pump 24
and the main pump 25 to the waiting speed N24w and N25w (step
S224).
[0200] The booster pump 24 is kept decelerating (step S225A), and
it is determined whether or not the speed N24 of the booster pump
24 has reached the waiting speed N24w (step S226A). If the speed
N24 of the booster pump 24 has not reached the waiting speed N24w
(if "NO" in step S226A), the booster pump 24 is kept decelerating
(step S225A). If the speed N24 of the booster pump 24 has reached
the waiting speed N24w (if "YES" in step S226A), the booster pump
24 is kept waiting at the waiting speed N24w (step S227A). When the
booster pump 24 reaches the waiting speed (for example, a
rotational speed equal to or lower than the lower limit at which
the motor control panel 31 can recognize the booster pump as
operating), the motor control panel 31 stops supplying power E2 to
the booster pump so that the booster pump 24 is driven by inertia
and the gas G2 exhausted from the process chamber 21 to keep
rotating at a rotational speed approximately equal to the waiting
speed.
[0201] On the other hand, the main pump 25 is kept decelerating
(step S225B), and it is determined whether or not the speed N25 of
the main pump 25 has reached the waiting speed N25w (step S226B).
If the speed N25 of the main pump 25 has not reached the waiting
speed N25w (if "NO" in step S226B), the main pump 25 is kept
decelerating (step S225B). If the speed N25 of the main pump 25 has
reached the waiting speed N25w (if "YES" in step S226B), the main
pump 25 is kept waiting at the waiting speed N25w (step S227B).
After step S224, steps S225A to S227A and steps S225B to S227B are
performed concurrently with each other.
[0202] After steps S227A and S227B, the process gas G1 is
introduced into the process chamber 21 (step S228). Then, a
pressure control start signal i1 for the process chamber 21 is
input from the process controller (not shown) to the pressure
controller 6 (step S229). The pressure P21 in the process chamber
21 is increased to a specified pressure P21a (higher than the rated
pressure P21r) (for example, 90% of the target pressure P21x). To
increase the pressure P21, the main pump 25 is decelerated (step
S231). Therefore, the pressure controller 6 sends a rotational
speed regulation signal i10 to the motor control panel 31, which
regulates the motor power E3 such that the speed N25 of the main
pump 25 decreases. The main pump 25 is in this way decelerated.
[0203] The pressure controller 6 determines whether or not the
pressure P21 in the process chamber 21 has reached the specified
pressure P21a (step S232). If the pressure P21 has not reached the
specified value P21a (if "NO" in step S232), the main pump 25 is
kept decelerating (step S231). If the pressure P21 in the process
chamber 21 has reached the specified value P21a (if "YES" in step
S232), pressure control is performed to bring the pressure P21 in
the process chamber 21 to the target pressure (desired pressure)
P21x (higher than the rated pressure P21r) (step S233). To regulate
the speed N25 of the main pump 25 (step S234), the pressure
controller 6 sends a rotational speed regulation signal i10 to the
motor control panel 31, which regulates the motor power E3 such
that the speed N25 of the main pump 25 decreases. The main pump 25
is in this way decelerated further.
[0204] The pressure controller 6 determines whether or not the
pressure P21 in the process chamber 21 has reached the target value
P21x (step S235). If the pressure P21 has not reached the target
pressure P21x (if "NO" in step S235), the speed N25 of the main
pump 25 is kept regulated, that is, the main pump 25 is kept
decelerating (step S234). If the pressure P21 in the process
chamber 21 has reached the target pressure P21x (if "YES" in step
S235), the pressure controller 6 regulates the speed N25 of the
main pump 25 such that the pressure P21 in the process chamber 21
is kept at the target pressure P21x (step S236). After that, a
pressure control stop signal (not shown) to stop the pressure
control in the process chamber 21 is input from the process
controller (not shown) to the pressure controller 6 (step S237),
and the pressure control to bring the pressure P21 in the process
chamber 21 to the target pressure P21x is terminated (step
S238).
[0205] With reference to FIG. 16, the sixth operation method for
the vacuum evacuation device 2 is described in view of the passage
of time. FIG. 12 is also referenced when necessary.
[0206] Before time t1, the booster pump 24 and the main pump 25 are
respectively rotating at the rated rotational speed N24r and N25r,
and the pressure P21 in the process chamber 21 is at the rated
pressure P21r. At time t1, process information i2 is input to the
pressure controller 6. Immediately after that, the booster pump 24
starts decelerating to bring the speed N24 of the booster pump 24
to the waiting speed N24w, and the main pump 25 starts decelerating
to bring the speed N25 of the main pump 25 to the waiting speed
N25w.
[0207] At time t2, as the speed N24 and N25 of the booster pump 24
and the main pump 25 respectively decreases, the pressure P21 in
the process chamber 21 starts increasing gradually. At time t3, the
speed N25 of the main pump 25 reaches the waiting rotational speed
N25w, and the main pump 25 starts waiting at the waiting speed
N25w. At time t4, the speed N24 of the booster pump 24 reaches the
waiting rotational speed N24w, and the booster pump 24 starts
waiting at the waiting speed N24w.
[0208] At time t5, introduction of the process gas G1 into the
process chamber 21 is started. At time t6, a pressure control start
signal i1 is input to the pressure controller 6, and pressure
increase by decreasing the speed N25 of the main pump 25 (one of
the pumps) is started to bring the pressure P21 to a specified
pressure P21a (for example, 90% of the target pressure P21x). At
time t7, the pressure P21 in the process chamber 21 reaches the
specified pressure P21a, and the pressure controller 6 starts
controlling the pressure P21 in the process chamber 21. That is,
the main pump 25 is decelerated so as to bring the pressure P21 in
the process chamber 21 to the target pressure P21x. As the main
pump 25 decelerates, the increase rate of the pressure P21 in the
process chamber 21 increases. At time t8, the pressure P21 in the
process chamber 21 reaches the target pressure P21x. The pressure
P21 in the process chamber 21 is still kept controlled to the
target pressure P21x, and accordingly the speed N25 of the main
pump 25 is regulated to the rotational speed corresponding to the
target pressure P21x. This (the state where the target pressure
P21x is kept) is the pressure condition in the process chamber 21
suitable for the process reaction. At time t9, a pressure control
stop signal (not shown) is input to the pressure controller 6, and
the control of the pressure P21 in the process chamber 21 is
finished. During the period between time t7 and time t8, when the
pressure control is performed, the pressure P21 in the process
chamber 21 monotonously increases without hunting or the like.
[0209] For description of the waiting rotational speed N25w for the
main pump 25 in this sixth operation method, the description of the
waiting rotational speed N24w for the booster pump 24 in the fifth
operation method described before is applied, with the term
"booster pump 24" replaced by the term "main pump 25", "rotational
speed N24" by "rotational speed N25", "rated rotational speed N24r"
by "rated rotational speed N25r", and "waiting rotational speed
N24w" by "waiting rotational speed N25w".
[0210] For description of the specified pressure P21a related to
the main pump 25 in this sixth operation method, the description of
the specified pressure P21a related to the booster pump 24 in the
fifth operation method described before is applied, with the term
"booster pump 24" replaced by the term "main pump 25".
[0211] In this sixth operation method, the main pump 25 is
decelerated to increase the pressure P21 from the rated pressure
P21r to the specified pressure P21a (90% of the target pressure),
and the deceleration of the main pump 25 is stopped when the
pressure P21 reaches the specified pressure P21a. Thus, the
pressure control is not performed during that period by regulating
the speed N25 of the main pump 25. In this operation method, the
pressure is increased by simply decreasing the speed N25 of the
main pump 25, which requires a period (t7-t1) much shorter than in
an approach through control of the pressure P21.
[0212] Meanwhile, in the case where the pressure P21 is increased
by decelerating the main pump 25 continuously until the pressure
P21 reaches the target pressure P21x, the pressure P21 will not
stop increasing immediately after reaching the target pressure P21x
and will overshoot the target pressure P21x. Therefore, in this
operation method, the pressure is increased to the specified
pressure P21a (90% of the target pressure P21x) by deceleration,
and after that, controlled by regulating of the rotational speed
N25 to prevent the pressure P21 from overshooting the target
pressure P21. This combination of the rotational speed N25
decelerating operation and the subsequent pressure control can
prevent the pressure 21 from overshooting and reduce the period
required to achieve the target pressure P21x (t8-t6).
[0213] The timing for the introduction of the process gas G1 is
determined so as to prevent overload operation of the booster pump
24 and the main pump 25 between time t1 and time t9, by
comprehensively considering the type of the process gas G1, flow
rate of the process gas to be introduced, changes in the pressure
P21 in the process chamber 21, speed N24 of the booster pump 24,
speed N25 of the main pump 25, etc. In the case of this operation
method where the process gas G1 is introduced at such a large flow
rate as to exceed the operating range of the booster pump 24 (for
example, 10 SLM or more), the process gas G1 is introduced after
the booster pump 24 reaches the waiting speed N24w and the supply
of the power E2 is stopped so that the pump 24 rotates by
inertia.
[0214] In this sixth operation method, the state where the target
pressure P21x is kept is the pressure condition in the process
chamber 21 suitable for the process reaction.
[0215] In this operation method, the pressure controller 6 computes
the waiting speed N24w for the booster pump 24 and the waiting
speed N25w for the main pump 25 based on the process information
related to process reaction, and the main pump 25 is decelerated to
and kept waiting at the waiting speed N25w before pressure control
to bring the pressure P21 in the process chamber 21 to the target
pressure P21x. Therefore, it is possible to bring the pressure P21
in the process chamber 21 to a desired pressure suitable for the
process reaction in a short period without the main pump 25 being
overloaded in the pressure control performed by regulating the
speed N25 of the main pump 25, regardless of the process reaction
condition. Since the booster pump 24 is rotating at the waiting
speed when the process gas G1 is introduced, the booster pump 24
will not be overloaded.
[0216] In addition, the waiting speed N25w for the main pump 25 can
be determined and the speed N25 of the main pump 25 can be
decreased in an appropriate manner. Therefore, the pressure P21 in
the process chamber 21 can be made to monotonously increase without
hunting to reach the target pressure P21x in a short period, and
can be prevented from overshooting the target pressure P21 during
the pressure increasing process.
[0217] In this sixth operation method, not the speed N24 of the
booster pump 24 but only the speed N25 of the main pump 25 is
regulated. This is suitable for the case where the flow rate of the
process gas introduced is relatively large (for example, 10 SLM or
more) and the difference between the rated pressure P21r of the
process chamber 21 and the target pressure P21x suitable for the
process reaction is relatively large, that is, the rated pressure
P21r is a high vacuum (0.1 Torr or less) and the target pressure
P21x is a relatively high vacuum (for example, 1 Torr or more),
resulting in a relatively large pressure control range.
[0218] Next, with reference to FIG. 17 and where necessary FIG. 12
and FIG. 18 to be described later, the steps of a seventh operation
method for the vacuum evacuation device 2 according to the second
embodiment of the present invention are described.
[0219] Before pressure reduction control in the process chamber 21
by the pressure controller 6, the atmosphere (air) is introduced
into the process chamber 21 and the process chamber 21 is at
atmospheric pressure. That is, the process chamber is once exposed
to the atmosphere and filled with air. The booster pump 24 is
stationary, and the main pump 25 is operated at the rated
rotational speed N25r (step S241). On receiving process information
i2 from the process controller (not shown) (step S242), the process
controller 6 computes a waiting rotational speed N25w for the main
pump 25 based on the received process information i2 (step S243).
When the computation is finished, the pressure controller 6
decelerates the main pump 25 to bring the speed N25 of the main
pump 25 to the waiting speed N25w (step S244).
[0220] Then, it is determined whether or not the speed N25 of the
main pump 25 has reached the waiting speed N25w (step S245). If the
speed N25 of the main pump 25 has not reached the waiting speed
N25w (if "NO" in step S245), the main pump 25 is kept decelerating
(step S244). If the speed N25 of the main pump 25 has reached the
waiting speed N25w (if "YES" in step S245), the main pump 25 is
kept waiting at the waiting speed N25w (step S246).
[0221] After that, a pressure reduction control start signal (not
shown) to reduce the pressure P21 in the process chamber 21 at the
target (desired) pressure reduction rate PR21x is input from the
process controller (not shown) to the pressure controller 6 (step
S247), and pressure reduction control for the pressure P21 in the
process chamber 21 is performed by regulating the speed N25 of the
main pump 25 (step S248). The pressure controller 6 sends a
rotational speed regulation signal i10 to the motor control panel
31, which regulates the motor power E3 such that the speed N25 of
the main pump 25 increases. The main pump 25 is in this way
accelerated (step S249).
[0222] While the main pump 25 is accelerating, the pressure
controller 6 determines whether or not the speed N25 of the main
pump 25 has reached the rated speed N25r (step S250). If the speed
N25 of the main pump 25 has not reached the rated speed N25r (if
"NO" in step S250), it is determined whether or not the pressure
reduction rate PR21 of the pressure P21 in the process chamber 21
is higher than the target pressure reduction rate PR21x (step
S251). Whether a pressure reduction rate (unit Torr/sec) is larger
or smaller is determined by absolute value of inclination of
pressure curve. If the pressure reduction rate PR21 in the process
chamber 21 is lower than the target pressure reduction rate PR21x
(if "NO" in step S251), the process returns to step S249 to
accelerate the rotational speed N25 of the main pump 25. If the
pressure reduction rate PR21 in the process chamber 21 is higher
than the target pressure reduction rate PR21x (if "YES" in step
S251), the process returns to the point before the step S250 to
decelerate the rotational speed N25 of the main pump 25.
[0223] If the rotational speed N25 of the main pump 25 reaches the
rated rotational speed N25r (if "YES" in step S250), regulation of
the rotational speed of the main pump 25 is stopped (step S253).
Then the rotational speed N25 of the main pump 25 is kept at the
rated rotational speed N25r, and pressure reduction control of the
pressure P21 of the process chamber 21 to the target pressure
reduction rate PR21x terminates (step S254). After the pressure
reduction control terminates, the booster pump 24 is started to
bring the pressure P21 in the process chamber 21 to the rated
pressure P21r (step S255).
[0224] The pressure reduction rate is included in the process
information i2.
[0225] With reference to FIG. 18, the seventh operation method for
the vacuum evacuation device 2 is described in view of the passage
of time. FIG. 12 is also referenced when necessary.
[0226] Before time t1, the booster pump 24 is stationary, the main
pump 25 is rotating at the rated rotational speed N25r. Since the
electromagnetic valve 9 mounted on the exhaust piping 12 between
the process chamber 21 and the booster pump 24 is closed and an
atmospheric release valve (not shown) mounted on the process
chamber 21 is opened, the pressure P21 in the process chamber 21 is
at atmospheric pressure. After the pressure P21 becomes equal to
the atmospheric pressure, the atmospheric release valve is closed.
Then, at time t1, process information i2 is input to the pressure
controller 6 for slow evacuation of the process chamber 21.
Immediately after that, the main pump 25 starts decelerating to
bring the speed N25 of the main pump 25 to the waiting speed N25w.
At time t2, the speed N25 of the main pump 25 reaches the waiting
rotational speed N25w, and the main pump 25 starts waiting at the
waiting speed N25w. During this period, the electromagnetic valve 9
remains closed, and hence the pressure P21 in the process chamber
21 and the pressure P13 on the exhaust side of the booster pump 24
do not change.
[0227] At time t3, a pressure reduction control start signal (not
shown) is input to the pressure controller 6, and the
electromagnetic valve 9 is opened to start control that regulates
the speed N25 of the main pump 25 so as to bring the pressure
reduction rate PR21 (evacuation rate (in Torr/sec)) for the
pressure P21 in the process chamber 21 to the target value PR21x.
That is, the pressure reduction rate PR21 in the process chamber 21
is controlled to the constant target value PR21x by regulating the
speed N25 of the main pump 25 so as to increase. During this
period, the pressure P13 on the exhaust side of the booster pump 24
is also reduced at an approximately constant pressure reduction
rate. As the speed N25 of the main pump 25 increases, the pressure
P21 in the process chamber 21 decreases from atmospheric pressure
and the degree of vacuum is increased.
[0228] At time t4, the pressure P21 in the process chamber 21
reaches the rated pressure P21r and the control to regulate the
pressure reduction rate PR21 to the constant value terminates and
the slow evacuation operation terminates. At time t5, that is,
after the pressure P21 in the process chamber 21 reaches the rated
pressure P21r and the slow evacuation operation terminates, a
startup signal (not shown) is sent from the pressure controller 6
to the motor control panel 31 to start up the booster pump 24. At
time t6, the pressure P21 in the process chamber 21 reaches the
rated value P21r. At time t7, the speed N24 of the booster pump 24
reaches the rated speed N24w, and the vacuum evacuation device 2
shifts to rated operation.
[0229] The pressure controller 6 computes the waiting speed N25w
for the main pump 25 based on the process information related to
process reaction, and the main pump 25 is kept waiting at the
waiting speed N25w before pressure reduction control to reduce the
pressure P21 in the process chamber 21 at the target pressure
reduction rate PR21x. Therefore, it is possible to bring the
pressure reduction rate PR21 in the process chamber 21 to a desired
value PR21x suitable for the process reaction in a short period
without the main pump 25 being overloaded in the pressure reduction
control performed by regulating the speed N25 of the main pump 25,
regardless of the process reaction condition. The waiting speed
N25w for the main pump 25 and the increase in the speed N25 of the
main pump 25 are determined appropriately such that the pressure in
the process chamber 21 monotonously decreases without hunting,
thereby allowing the pressure reduction rate PR21 in the process
chamber 21 to reach the target pressure reduction rate PR21x in a
short period.
[0230] Since the pressure reduction (evacuation) is performed at
the constant specified pressure reduction rate PR21x (evacuation
rate), it is possible to prevent particles produced in the process
chamber 21 from flying around when the process chamber 21 is
evacuated by the main pump 25.
[0231] In this operation method, since the pressure reduction rate
is constant from the time when the pressure P21 in the process
chamber 21 is at atmospheric pressure, the speed of a main pump 25
capable of sucking gas with a high suction pressure and at a large
flow rate is regulated. Also in this operation method, when the
process chamber 21 is at or close to atmospheric pressure, which is
out of the operating condition of the booster pump 24, the booster
pump 4 does not operate until the pressure in the process chamber
reaches a specified pressure.
[0232] In this operation method, the state where the pressure
reduces at the target pressure reduction rate PR21x is the pressure
condition in the process chamber 21 suitable for the process
reaction.
[0233] This embodiment is the case where the target value of the
process chamber 21 is higher than 0.5 Torr and thus, depending on
the process condition, the turbo molecular pump 4 (FIG. 1) as a
first vacuum pump is not necessary. In this embodiment, compared
with the turbo molecular pump 4, the booster pump 24 has shorter
startup time to the rated rotational speed, and the particularly
shorter decelerating time from the rated rotational speed to a stop
and thus the booster pump 24 enables shorter pressure control time
of the process chamber 21 and improved throughput of the products
processed by the process reaction in the process chamber 21.
Further this embodiment can provide the vacuum evacuation device 2
of the simple structure without a pressure gauge to measure the
exhaust side pressure of the booster pump 24.
[0234] With reference to FIG. 19, a method for computing
(calculating) a waiting rotational speed based on process
information is described. FIG. 19 is a chart of a type of gas (for
example, a nitrogen gas) as the process gas G1 to be introduced
into the process chamber 21 (FIG. 1). The vertical axis represents
process pressure (target pressure P21x in the process chamber 21
(FIG. 1)), and the horizontal axis represents gas flow rate (flow
rate of the process gas G1 to be introduced into the process
chamber 21). The chart is prepared for each type of gas to be
introduced, and sent to the pressure controller 6 (FIG. 1) as
process information i2 (FIG. 1) as described before.
[0235] In the drawing, the gas flow rate is divided into six
regions between Q1 and Q7, and the pressure is divided into seven
regions between P1 and P8, resulting in a total of 42 blocks.
[0236] As shown in the drawing, the region with the pressure
between P7 and P8, and the region with the pressure between P5 and
P7 and the flow rate between Q4 and Q7 include blocks A1 to A12,
for which the second operation method is adopted. In the case of
these blocks, only the speed N5 of the dry pump 5 (FIG. 1) is
regulated to control the pressure P21 in the process chamber 21,
and the turbo molecular pump 4 (FIG. 1) is stationary, or is kept
rotating at a speed approximately equal to a waiting speed driven
by inertia and a gas G2 exhausted from the process chamber 21 by
stopping the supply of power E2 to the turbo molecular pump 4 by
the motor control panel 10 when the turbo molecular pump 4 reaches
the waiting speed (for example, a rotational speed equal to or
lower than the lower limit at which the motor control panel 10 can
recognize the turbo molecular pump 4 as operating). For each of the
blocks A1 to A12, there is stored a waiting speed N5w for the dry
pump 5.
[0237] As shown in the drawing, the region with the pressure
between P7 and P8, and the region with the pressure between P5 and
P7 and the flow rate between Q4 and Q7 include blocks A1 to A12,
for which the sixth operation method is also adopted. In the case
of these blocks, only the speed N25 of the main pump 25 (FIG. 12)
is regulated to control the pressure P21 in the process chamber 21,
and the booster pump 24 (FIG. 12) is stationary, or is kept
rotating at a speed approximately equal to a waiting speed driven
by inertia and a gas G2 exhausted from the process chamber 21 by
stopping the supply of the power E2 to the booster pump 24 by the
motor panel 31 when the booster pump 24 reaches the waiting speed
(for example, a rotational speed equal to or lower than the lower
limit at which the motor panel 31 can recognize the booster pump 24
as operating). For each of the blocks A1 to A12, there is stored a
waiting speed N25w for the main pump 25.
[0238] As shown in the drawing, the region with the pressure
between P5 and P7 and the flow rate between Q1 and Q4, the region
with the pressure between P3 and P5, and the region with the
pressure between P2 and P3 and the flow rate between Q1 and Q3
include blocks B1 to B20, for which the fourth operation method is
adopted. In the case of these blocks, the speed N4 of the turbo
molecular pump 4 is regulated to control the pressure in the
process chamber 21, and the speed N5 of the dry pump 5 is regulated
to control the pressure P13 on the exhaust side of the turbo
molecular pump 4. For each of the blocks B1 to B20, there are
correspondingly stored a waiting speed N5w for the dry pump 5 and a
waiting speed N4w for the turbo molecular pump 4.
[0239] As shown in the drawing, the region with the pressure
between P5 and P7 and the flow rate between Q1 and Q4, the region
with the pressure between P3 and P5, and the region with the
pressure between P2 and P3 and the flow rate between Q1 and Q3
include blocks B1 to B20, for which the fifth operation method is
adopted. In the case of these blocks, the speed N24 of the turbo
molecular pump 24 is regulated to control the pressure in the
process chamber 21, and the speed N25 of the main pump 25 is kept
at the rated speed N25r. For each of the blocks B1 to B20, there is
stored a waiting speed N24w for the turbo molecular pump 24.
[0240] As shown in the drawing, the region with the pressure
between P2 and P3 and the flow rate between Q3 and Q7, and the
region with the pressure between P1 and P2 include blocks C1 to
C10, for which the first operation method is adopted. Only the
speed N4 of the turbo molecular pump 4 is regulated to control the
pressure P21 in the process chamber 21, and the speed N5 of the dry
pump 5 is kept at the rated speed N5r. For each of the blocks C1 to
C10, there is stored a waiting speed N4w for the turbo molecular
pump 4.
[0241] Based on the values for the target pressure P21x and the gas
flow rate included in the process information i2, the pressure
controller 6 computes to determine to which of the blocks A1 to
A12, B1 to B20 and C1 to C10 in the drawing the pair of values
belong, and the waiting speed stored for the determined block is
adopted.
[0242] Since an appropriate waiting rotational speed is computed
from the values for the target pressure P21x and the gas flow rate
based on the chart, it is possible to prevent overload operation of
the turbo molecular pump 4 (FIG. 1), and the dry pump 5 (FIG. 1)
the turbo molecular pump 24 (FIG. 12) and the main pump 25 (FIG.
12) to control the pressure P21 in the process chamber 21 (FIG. 1,
12) to the target pressure P21x in a short period in the first,
second, fourth, fifth and sixth operation methods.
[0243] With reference to FIG. 20, a method for computing
(calculating) the waiting rotational speed N5w, N25w for the dry
pump 5 (FIG. 1) and the main pump 25 (FIG. 12) respectively based
on process information in the third and seventh operation methods
is described. FIG. 20 is a chart of air to be introduced into the
process chamber 21 (FIG. 1, 12). The vertical axis represents
pressure reduction rate, and the horizontal axis represents
capacity of the process chamber 21. The chart is sent to the
pressure controller 6 (FIG. 1, 12) as process information i2 (FIG.
1, 12) as described before.
[0244] In the drawing, the process chamber capacity is divided into
five regions between V1 and V6, and the pressure reduction rate is
divided into five regions between PR1 and PR6, resulting in a total
of 25 blocks D1 to D25. For each of the blocks D1 to D25, there is
correspondingly stored a waiting speed N5w, N25w for the dry pump 5
and the main pump 25.
[0245] Based on the values for the pressure reduction rate and the
capacity of the process chamber 21 included in the process
information i2, the pressure controller 6 computes to determine to
which of the blocks D1 to D25 in the drawing the pair of values
belong, and the waiting speed N5w, N25w stored for the determined
block is adopted.
[0246] A suitable waiting speed N5w, N25w for the dry pump 5 (FIG.
1) and the main pump 25 (FIG. 12) is computed from the values for
the pressure reduction rate and the capacity of the process chamber
21 (FIG. 1, 12). Therefore, in the third and seventh operation
methods, overload operation of the dry pump 5 and the main pump 25
can be prevented, abrupt pressure variations in the process chamber
21 can be avoided, particles can be prevented from flying around,
and the pressure reduction rate in the process chamber 21 can be
controlled to the target pressure reduction rate PR21x in a short
period.
[0247] Embodiments of the present invention have been described in
detail above with reference to the drawings. The present invention
is not limited to those embodiments, but various design changes,
etc., may be made without departing from the essence of the present
invention. For example, the processing device may not necessarily
be of a vertical type but a horizontal type, and may not
necessarily be a batch type which processes multiple objects at a
time but a sheet fed type which processes objects one by one. The
object to be processed may not necessarily be a semiconductor wafer
but an LCD substrate, for example.
[0248] Symbols of main elements used in the above description are
explained hereafter. 1: substrate processing apparatus, 2: vacuum
evacuation device, 3: flow rate regulator, 4: turbomolecular pump
(vacuum pump, first vacuum pump), 5: dry pump (vacuum pump, second
vacuum pump), 6: pressure controller (control means), 7,8: pressure
gauge, 9: electromagnetic valve 10,11,31: motor control panel
(control means), 12,13: exhaust piping, 21: process chamber, 24:
dry booster pump (vacuum pump, first vacuum pump), 25: dry main
pump (vacuum pump, second vacuum pump)
* * * * *