US20070048145A1

US20070048145A1 - Vacuum evacuation device and method, and substrate processing apparatus and method

Info

Publication number: US20070048145A1
Application number: US11/501,793
Authority: US
Inventors: Katsutoshi Ishii; Ken Nakao; Takanobu Asano; Kota Umezawa; Hiroaki Ogamino; Tadashi Urata; Katsuaki Usui; Masafumi Inoue; Shinichi Sekiguchi; Hironobu Yamasaki
Original assignee: Individual
Current assignee: Ebara Corp
Priority date: 2005-08-12
Filing date: 2006-08-10
Publication date: 2007-03-01
Also published as: JP2007071200A; JP4825608B2

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.

Description

BACKGROUND OF THE INVENTION

1. Technical Field
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.
2. Related Art
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.
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.
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.
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.
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).
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.
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.
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.
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.
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.
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

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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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

FIG. 1 is a block diagram showing the structure of a vacuum evacuation device according to a first embodiment of the present invention.
FIG. 2 is a flowchart showing the steps of a first operation method for the vacuum evacuation device of FIG. 1.
FIG. 3 is a graph showing the timeline of the first operation method for the vacuum evacuation device of FIG. 1.
FIG. 4 is a flowchart showing the steps of a second operation method for the vacuum evacuation device of FIG. 1.
FIG. 5 is a graph showing the timeline of the second operation method for the vacuum evacuation device of FIG. 1.
FIG. 6 is a flowchart showing the steps of a third operation method for the vacuum evacuation device of FIG. 1.
FIG. 7 is a graph showing the timeline of the third operation method for the vacuum evacuation device of FIG. 1.
FIG. 8 is a flowchart showing the steps of a fourth operation method for the vacuum evacuation device of FIG. 1.
FIG. 9 is a graph showing the timeline of the fourth operation method for the vacuum evacuation device of FIG. 1.
FIG. 10 is a detailed sectional block view showing a portion of a process chamber of the vacuum evacuation device of FIG. 1.
FIG. 11 is a graph showing pressure changes over time in the third operation method for the vacuum evacuation device of FIG. 1.
FIG. 12 is a block diagram showing the structure of a vacuum evacuation device according to a second embodiment of the present invention.
FIG. 13 is a flowchart showing the steps of a fifth operation method for the vacuum evacuation device of FIG. 12.
FIG. 14 is a graph showing the timeline of the fifth operation method for the vacuum evacuation device of FIG. 12.
FIG. 15 is a flowchart showing the steps of a sixth operation method for the vacuum evacuation device of FIG. 12.
FIG. 16 is a graph showing the timeline of the sixth operation method for the vacuum evacuation device of FIG. 12.
FIG. 17 is a flowchart showing the steps of a seventh operation method for the vacuum evacuation device of FIG. 12.
FIG. 18 is a graph showing the timeline of the seventh operation method for the vacuum evacuation device of FIG. 12.
FIG. 19 is a chart for computing the waiting rotational speed based on the process pressure and the gas flow.
FIG. 20 is a chart for computing the waiting rotational speed based on the pressure reduction rate and the process chamber capacity.
FIG. 21 is a block diagram showing the structure of a conventional vacuum evacuation device.
FIG. 22 is a flowchart showing the steps of an operation method for the vacuum evacuation device of FIG. 21.
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

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.
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 ClF₃gas, and a reaction gas such as a SiH₂Cl₂gas.
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.
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.
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.
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).
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.
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.
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.
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.
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 N4 r and N5 r (step S1), and the process chamber 21 is at the rated pressure P21 r. On receiving process information i2 from the process controller (not shown) (step S2), the process controller 6 computes (calculates) a waiting rotational speed N4 w (lower than the rated speed N4 r) 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 N4 w (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 N5 r.
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 N4 w (step S7). If the speed N4 of the turbo molecular pump 4 has not reached the waiting speed N4 w (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 N4 w (if “YES” in step S7), the turbo molecular pump 4 is kept waiting at the waiting speed N4 w (step S8).
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 P21 a (higher than the rated pressure P21 r) (for example, 90% of the target pressure (desired pressure) P21 x). To bring the pressure P21 in the process chamber 21 to the specified pressure P21 a, 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.
The pressure controller 6 determines whether or not the pressure P21 in the process chamber 21 has reached the specified pressure P21 a 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 P21 a (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. P21 a (if “YES” in step S12), pressure control is performed to bring the pressure P21 in the process chamber 21 to the target pressure P21 x (higher than the rated pressure P21 r) (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.
The pressure controller 6 determines whether or not the pressure P21 in the process chamber 21 has reached the target pressure P21 x (step S15). If the pressure P21 has not reached the target pressure P21 x (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 P21 x (if “YES” in step S15), the pressure controller 6 keeps controlling the pressure P21 in the process chamber 21 to the target pressure P21 x (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 P21 x is terminated (step S18).
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.
Before time t1, the turbo molecular pump 4 and the dry pump 5 are respectively rotating at the rated rotational speed N4 r and N5 r, 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 P21 r and P13 r. 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 N4 w. The dry pump 5 is kept rotating at the rated speed N5 r 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 P13 r. 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.
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 P13 b at time 2′. At time t3, the speed N4 of the turbo molecular pump 4 reaches the waiting rotational speed N4 w, and the turbo molecular pump 4 starts waiting at the waiting speed N4 w. 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.
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 P21 a. At time t5, the pressure P21 in the process chamber 21 reaches the specified pressure P21 a (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 P21 x. 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 P21 x. As the turbo molecular pump 4 decelerates, the pressure P21 in the process chamber 21 again increases.
At time t6, the pressure P21 in the process chamber 21 reaches the target pressure P21 x, 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 P21 x 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 P21 x 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.
In this first operation method, the waiting speed N4 w 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 N4 r to the speed to be reached corresponding to the target pressure P21 of the process chamber 21, but initially from the rated speed N4 r to the waiting speed N4 w. On reaching the waiting speed N4 w, the rotational speed N4 is kept waiting at the waiting speed N4 w. The waiting speed N4 w is determined so as to prevent the pressure P21 from overshooting the target pressure P21 x 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 P21 x. 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 N4 w is not necessary and a pressure control start signal i1 may be input immediately after the waiting speed N4 w is reached to proceed to the pressure control.
The specified pressure P21 a is close to the target pressure P21 x of the process chamber 21, and slightly lower than the target pressure P21 x (for example, 80 to 95% of the target pressure P21 x). The specified pressure P21 a is determined such that the pressure P21 can monotonously increase to reach the target pressure P21 x and can be prevented from overshooting the target pressure P21 x during the pressure control to bring the pressure P21 to the target pressure P21 x performed after the turbo molecular pump 4 is decelerated to bring the pressure P21 in the process chamber 21 to the specified pressure P21 a.
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 P21 r to the specified pressure P21 a (90% of the target pressure), and the deceleration of the turbo molecular pump 4 is stopped when the pressure P21 reaches the specified pressure P21 a. Thus, the pressure control is not performed during that period according to the calculation of the deviation between the target pressure P21 x 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.
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 P21 x, the pressure P21 will not stop increasing immediately after reaching the target pressure P21 x and will overshoot the target pressure P21 x. Therefore, in this operation method, the pressure is increased to the specified pressure P21 a (90% of the target pressure P21 x) 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 P21 x (t6−t4).
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 N4 w.
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.
In the case where the range of changes in the rotational speed N4 (the difference between the rated speed N4 r and the rotational speed corresponding to the target pressure P21 x) is small, the pressure P21 in the process chamber 21 may not necessarily be controlled to the specified pressure P21 a. This can achieve simplified control and reduce the period for that control.
In this operation method, the pressure controller 6 computes the waiting speed N4 w 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 N4 w before pressure control to bring the pressure P21 in the process chamber 21 to the target pressure P21 x. 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 N4 w 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 P21 x in a short period, and can be prevented from overshooting the target pressure P21 during the pressure increasing process.
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 P21 r of the process chamber 21 and the target pressure P21 x suitable for the process reaction is relatively small, that is, the rated pressure P21 r is a high vacuum (0.1 Torr or less) and the target pressure P21 x is a relatively high vacuum (for example, 0.5 Torr or less), resulting in a relatively small pressure control range.
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 N4 r to the waiting speed N4 w, then decreased until the pressure P21 reaches the specified pressure P21 a, and then regulated so as to bring the pressure P21 to the target pressure P21 x, and it is possible to reduce the period to bring the rotational speed N4 from the rated speed N4 r to the speed to be reached corresponding to the target pressure P21 x (t6−t1).
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.
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 N4 r and N5 r (step S21). On receiving process information i2 (step S22), the process controller 6 computes a waiting rotational speed N4 w (lower than the rated speed N4 r) for the turbo molecular pump 4 and a waiting rotational speed N5 w (lower than the rated speed N5 r) 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 N4 w and N5 w (step S24).
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 N4 w (step S26A). If the speed N4 of the turbo molecular pump 4 has not reached the waiting speed N4 w (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 N4 w (if “YES” in step S26A), the turbo molecular pump 4 is kept waiting at the waiting speed N4 w (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.
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 N5 w (step S26B). If the speed N5 of the dry pump 5 has not reached the waiting speed N5 w (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 N5 w (if “YES” in step S26B), the dry pump 5 is kept waiting at the waiting speed N5 w (step S27B) After step S24, steps S25A to S27A and steps S25B to S27B are performed concurrently with each other.
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 P21 a (higher than the rated pressure P21 r) (for example, 90% of the target pressure P21 x). 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.
The pressure controller 6 determines whether or not the pressure P21 in the process chamber 21 has reached the specified pressure P21 a (step S32). If the pressure P21 has not reached the specified value P21 a (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 P21 a (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) P21 x (higher than the rated pressure P21 r) (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.
The pressure controller 6 determines whether or not the pressure P21 in the process chamber 21 has reached the target value P21 x (step S35). If the pressure P21 has not reached the target pressure P21 x (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 P21 x (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 P21 x (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 P21 x is terminated (step S38).
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.
Before time t1, the turbo molecular pump 4 and the dry pump 5 are respectively rotating at the rated rotational speed N4 r and N5 r, and the pressure P21 in the process chamber 21 is at the rated pressure P21 r. 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 N4 w, and the dry pump 5 starts decelerating to bring the speed N5 of the dry pump 5 to the waiting speed N5 w.
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 N5 w, and the dry pump 5 starts waiting at the waiting speed N5 w. At time t4, the speed N4 of the turbo molecular pump 4 reaches the waiting rotational speed N4 w, and the turbo molecular pump 4 starts waiting at the waiting speed N4 w.
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 P21 a (for example, 90% of the target pressure P21 x). At time t7, the pressure P21 in the process chamber 21 reaches the specified pressure P21 a, 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 P21 x. 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 P21 x. The pressure P21 in the process chamber 21 is still kept controlled to the target pressure P21 x, and accordingly the speed N5 of the dry pump 5 is regulated to the rotational speed corresponding to the target pressure P21 x. This (the state where the target pressure P21 x 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.
For description of the waiting rotational speed N5 w for the dry pump 5 in this second operation method, the description of the waiting rotational speed N4 w 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 N4 r” by “rated rotational speed N5 r”, and “waiting rotational speed N4 w” by “waiting rotational speed N5 w”.
For description of the specified pressure P21 a related to the dry pump 5 in this second operation method, the description of the specified pressure P21 a 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”.
In this second operation method, the dry pump 5 is decelerated to increase the pressure P21 from the rated pressure P21 r to the specified pressure P21 a (90% of the target pressure), and the deceleration of the dry pump 5 is stopped when the pressure P21 reaches the specified pressure P21 a. 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.
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 P21 x, the pressure P21 will not stop increasing immediately after reaching the target pressure P21 x and will overshoot the target pressure P21 x. Therefore, in this operation method, the pressure is increased to the specified pressure P21 a (90% of the target pressure P21 x) 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 P21 x (t8−t6).
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 N4 w and the supply of the power E2 is stopped so that the pump rotates by inertia.
In this second operation method, the state where the target pressure P21 x is kept is the pressure condition in the process chamber 21 suitable for the process reaction.
In this operation method, the pressure controller 6 computes the waiting speed N4 w for the turbo molecular pump 4 and the waiting speed N5 w 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 N5 w before pressure control to bring the pressure P21 in the process chamber 21 to the target pressure P21 x. 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.
In addition, the waiting speed N5 w 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 P21 x in a short period, and can be prevented from overshooting the target pressure P21 during the pressure increasing process.
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 P21 r of the process chamber 21 and the target pressure P21 x suitable for the process reaction is relatively large, that is, the rated pressure P21 r is a high vacuum (0.1 Torr or less) and the target pressure P21 x is a relatively high vacuum (for example, 0.5 Torr or more), resulting in a relatively large pressure control range.
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.
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 N5 r (step S41). On receiving process information i2 from the process controller (not shown) (step S42), the process controller 6 computes a waiting rotational speed N5 w 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 N5 w (step S44).
Then, it is determined whether or not the speed N5 of the dry pump 5 has reached the waiting speed N5 w (step S45). If the speed N5 of the dry pump 5 has not reached the waiting speed N5 w (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 N5 w (if “YES” in step S45), the dry pump 5 is kept waiting at the waiting speed N5 w (step S46).
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 PR21 x 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).
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 N5 r (step S50). If the speed N5 of the dry pump 5 has not reached the rated speed N5 r (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 P21 b (step S52). If the pressure P21 in the process chamber 21 is higher than the specified value P21 b (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 PR21 x (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 PR21 x (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 PR21 x (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.
If the pressure P21 in the process chamber 21 is lower than the specified value P21 b (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).
If the speed N5 of the dry pump 5 has reached the rated speed N5 r (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 N5 r, and the pressure reduction control to reduce the pressure P21 in the process chamber 21 at the target pressure reduction rate PR21 x is terminated (step S56).
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.
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.
Before time t1, the turbo molecular pump 4 is stationary, the dry pump 5 is rotating at the rated rotational speed N5 r, 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 N5 w. At time t2, the speed N5 of the dry pump 5 reaches the waiting rotational speed N5 w, and the dry pump 5 starts waiting at the waiting speed N5 w. 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.
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 PR21 x. That is, the pressure reduction rate PR21 in the process chamber 21 is controlled to the constant target value PR21 x 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.
At time t4, the pressure P21 in the process chamber 21 reaches the specified pressure P21 b, 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 N5 r, 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 P21 r. At time t7, the speed N4 of the turbo molecular pump 4 reaches the rated speed N4 w, and the vacuum evacuation device 2 shifts to rated operation.
The pressure controller 6 computes the waiting speed N5 w 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 N5 w before pressure reduction control to reduce the pressure P21 in the process chamber 21 at the target pressure reduction rate PR21 x. Therefore, it is possible to bring the pressure reduction rate PR21 in the process chamber 21 to a desired value PR21 x 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 N5 w 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 PR21 x in a short period.
Since the pressure reduction (evacuation) is performed at the constant specified pressure reduction rate PR21 x (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.
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.
In this operation method, the state where the pressure reduces at the target pressure reduction rate PR21 x is the pressure condition in the process chamber 21 suitable for the process reaction.
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.
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 N4 r and N5 r (step S61). On receiving process information i2 (step S62), the process controller 6 computes the waiting speed N4 w for the turbo molecular pump 4 and the waiting speed N5 w 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 N4 w and N5 w (step S64).
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 N4 w (step S67A). If the speed N4 of the turbo molecular pump 4 has not reached the waiting speed N4 w (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 N4 w (if “YES” in step S67A), the turbo molecular pump 4 is kept waiting at the waiting speed N4 w (step S68A)
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 N5 w (step S67B). If the speed N5 of the dry pump 5 has not reached the waiting speed N5 w (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 N5 w (if “YES” in step S67B), the dry pump 5 is kept waiting at the waiting speed N5 w (step S68B). After step 65, steps S66A to S68A and steps S66B to S68B are performed concurrently with each other.
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) P21 x 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 P13 c (for example, 80% of the target pressure P13 x) 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 P13 c (step S71). If the pressure P13 on the exhaust side of the turbo molecular pump 4 has not reached the specified pressure P13 c (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 P13 c (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 P13 x 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 P13 x (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 P13 x (step S74).
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 ΔP21 d (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 ΔP21 d (if the amount of increase is less than the specified pressure ΔP21 d) (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 ΔP21 d (if the amount of increase is not less than the specified pressure ΔP21 d) (if “YES” in step S76), the speed of the turbo molecular pump 4 is increased by a certain rotational speed ΔN4 d (for example, 20% of the rated speed) and the turbo molecular pump 4 is kept at the increased rotational speed N4 d (step S77).
Then, it is determined whether or not the pressure on the exhaust side of the turbo molecular pump 4 has reached the specified pressure P13 c (for example, 80% of the target pressure P13 x) (step S78). If the specified pressure P13 c has not been reached (if less than the specified pressure P13 c) (if “NO” in step S78), the increased speed N4 d is kept (step S77). If the specified pressure P13 c has been reached (if not less than the specified pressure P13 c) (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 P21 a (for example, 90% of the target pressure P21 x) (step S79).
It is determined whether or not the pressure in the process chamber 21 has reached the specified pressure P21 a (step S80). If the specified pressure P21 a has not been reached (if “NO” in step S80), the turbo molecular pump 4 is kept decelerating (step S79). If the specified pressure P21 a 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 P21 x (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 P21 x (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).
After step S69, steps S70 to S74 and steps S75 to S83 are performed concurrently with each other as two control systems.
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.
Before time t1, the turbo molecular pump 4 and the dry pump 5 are respectively rotating at the rated rotational speed N4 r and N5 r, and the pressure P21 in the process chamber 21 is at the rated value P21 r. 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 N4 w and N5 w.
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.
At time t3, the speed N5 of the dry pump 5 reaches the waiting rotational speed N5 w, after which the dry pump 5 waits at the waiting speed N5 w. At time t4, the speed N4 of the turbo molecular pump 4 reaches the waiting rotational speed N4 w, after which the turbo molecular pump 4 waits at the waiting speed N4 w.
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 P13 c (for example, 80% of the target pressure P13 x). The speed N5 of the dry pump 5 is also decreased so that the pressure P21 in the process chamber 21 starts increasing.
At time t6, when the pressure P21 in the process chamber 21 auhas increased by the specified pressure ΔP 21 d (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 ΔN4 d (for example, 20% of the rated speed) and is kept at the increased speed N4 d (for example, the current rotational speed plus 20% of the rated speed).
At time t7, the pressure P13 on the exhaust side of the turbo molecular pump 4 reaches the specified pressure P13 c, and pressure control is performed to bring the pressure P13 on the exhaust side to the target pressure P13 x 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 P21 a ((for example, 90% of the target pressure P21 x) by regulating the speed N4 of the turbo molecular pump 4.
At time t8, the pressure P13 on the exhaust side of the turbo molecular pump 4 reaches the target pressure P13 x. 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 P13 x.
At time t9, the pressure P21 in the process chamber 21 reaches the specified pressure P21 a, and pressure control is started to bring the pressure P21 in the process chamber 21 to the target pressure P21 x 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 P21 x, and the pressure control is kept on to keep the pressure P21 in the process chamber 21 at the target pressure P21 x.
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.
In this operation method, the pressure controller 6 computes the waiting speed N4 w and N5 w 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 N4 w before pressure control to bring the pressure P21 in the process chamber 21 to the target pressure P21 x while the dry pump 5 is kept waiting at the waiting speed N5 w before pressure control to bring the pressure P13 on the exhaust side of the turbo molecular pump 4 to the target pressure P13 x. Therefore, it is possible to bring the pressure P21 in the process chamber 21 to a desired pressure P21 x 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 N4 w and N5 w 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 P21 x in a short period.
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.
In this operation method, after both the turbo molecular pump 4 and the dry pump 5 are kept waiting at the appropriate waiting speed N4 w and N5 w, 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 P13 x 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 P21 x before the pressure P13 reaches the target pressure P13 x, 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.
If the pressure P21 in the process chamber 21 reaches the target pressure P21 x before the pressure P13 on the exhaust side of the turbo molecular pump 4 reaches the target pressure P13 x, the speed N4 of the turbo molecular pump 4 is kept at the speed at which the target pressure P21 x 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 P13 x, 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 P21 x after the pressure P13 on the exhaust side reaches the target pressure P13 x, thereby preventing the pressure P21 from overshooting.
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 N4 w and N5 w, when the pressure in the process chamber 21 is increased by the specified value ΔP21 d (20 mTorr in the above description) or more, the speed N4 of the turbo molecular pump 4 is increased by the certain rotational speed ΔN4 d. 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.
In this operation method, the state where the target pressure P21 x is kept is the desired pressure condition in the process chamber 21 suitable for the process reaction. Also, the state where the target pressure P13 x is kept is the desired pressure condition on the exhaust side of the turbo molecular pump 4.
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.
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 32 a and an outer tube 32 b, the reaction tube 21 may be of a single tube structure (not shown) with only an outer tube 32 b. 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.
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° C., is provided around the reaction tube 21.
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.
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.
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.
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.
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 (SiO₂), to be deposited on a part where the pressure varies.
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.
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.
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.
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.
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 O₂and hydrogen H₂are directly introduced to form an oxide film on a substrate.
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.
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 ClF₃gas, and a reaction gas such as a SiH₂Cl₂gas.
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.
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.
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.
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).
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.
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.
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.
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.
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 N24 r and N25 r (step S201), and the process chamber 21 is at the rated pressure P21 r. On receiving process information i2 from the process controller (not shown) (step S202), the process controller 6 computes (calculates) a waiting rotational speed N24 w (lower than the rated speed N24 r) 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 N24 w (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 N25 r.
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 N24 w (step S207). If the speed N24 of the booster pump 24 has not reached the waiting speed N24 w (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 N24 w (if “YES” in step S207), the booster pump 24 is kept waiting at the waiting speed N24 w (step S208).
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 P21 a (higher than the rated pressure P21 r) (for example, 90% of the target pressure P21 x). To bring the pressure P21 in the process chamber 21 to the specified pressure P21 a, 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.
The pressure controller 6 determines whether or not the pressure P21 in the process chamber 21 has reached the specified pressure P21 a 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 P21 a (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 P21 a (if “YES” in step S212), pressure control is performed to bring the pressure P21 in the process chamber 21 to the target pressure P21 x (higher than the rated pressure P21 r) (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.
The pressure controller 6 determines whether or not the pressure P21 in the process chamber 21 has reached the target pressure P21 x (step S215). If the pressure P21 has not reached the target pressure P21 x (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 P21 x (if “YES” in step S215), the pressure controller 6 keeps controlling the pressure P21 in the process chamber 21 to the target pressure P21 x (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 P21 x is terminated (step S218).
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.
Before time t1, the booster pump 24 and the main pump 25 are respectively rotating at the rated rotational speed N24 r and N25 r, and the pressure P21 in the process chamber 21 is at the rated pressure P21 r. 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 N24 w. The main pump 25 is kept rotating at the rated speed N25 r 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 P13 r. 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.
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 N24 w, and the booster pump 24 starts waiting at the waiting speed N24 w. 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.
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 P21 a. At time t5, the pressure P21 in the process chamber 21 reaches the specified pressure P21 a (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 P21 x. 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 P21 x. As the booster pump 24 decelerates, the pressure P21 in the process chamber 21 again increases.
At time t6, the pressure P21 in the process chamber 21 reaches the target pressure P21 x, 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 P21 x 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 P21 x 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.
In this fifth operation method, the waiting speed N24 w 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 N24 r to the speed to be reached corresponding to the target pressure P21 of the process chamber 21, but initially from the rated speed N24 r to the waiting speed N24 w. On reaching the waiting speed N24 w, the rotational speed N24 is kept waiting at the waiting speed N24 w. The waiting speed N24 w is determined so as to prevent the pressure P21 from overshooting the target pressure P21 x 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 P21 x. 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 N24 w is not necessary and a pressure control start signal i1 may be input immediately after the waiting speed N24 w is reached to proceed to the pressure control.
The specified pressure P21 a is close to the target pressure P21 x of the process chamber 21, and slightly lower than the target pressure P21 x (for example, 80 to 95% of the target pressure P21 x). The specified pressure P21 a is determined such that the pressure P21 can monotonously increase to reach the target pressure P21 x and can be prevented from overshooting the target pressure P21 x during the pressure control to bring the pressure P21 to the target pressure P21 x performed after the booster pump 24 is decelerated to bring the pressure P21 in the process chamber 21 to the specified pressure P21 a.
In this operation method, the booster pump 24 is decelerated to increase the pressure P21 in the process chamber 21 from the rated pressure P21 r to the specified pressure P21 a (90% of the target pressure), and the deceleration of the booster pump 24 is stopped when the pressure P21 reaches the specified pressure P21 a. Thus, the pressure control is not performed during that period according to the calculation of the deviation between the target pressure P21 x 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.
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 P21 x, the pressure P21 will not stop increasing immediately after reaching the target pressure P21 x and will overshoot the target pressure P21 x. Therefore, in this operation method, the pressure is increased to the specified pressure P21 a (90% of the target pressure P21 x) 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 P21 x (t6−t4).
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 N24 w.
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.
In the case where the range of changes in the rotational speed N24 (the difference between the rated speed N24 r and the rotational speed corresponding to the target pressure P21 x) is small, the pressure P21 in the process chamber 21 may not necessarily be controlled to the specified pressure P21 a. This can achieve simplified control and reduce the period for that control.
In this operation method, the pressure controller 6 computes the waiting speed N24 w 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 N24 w before pressure control to bring the pressure P21 in the process chamber 21 to the target pressure P21 x. 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 N24 w 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 P21 x in a short period, and can be prevented from overshooting the target pressure P21 during the pressure increasing process.
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 P21 r of the process chamber 21 and the target pressure P21 x suitable for the process reaction is relatively small, that is, the rated pressure P21 r is a high vacuum (0.1 Torr or less) and the target pressure P21 x is a relatively high vacuum (for example, 0.5 Torr or less), resulting in a relatively small pressure control range.
In this operation method, however, the rotational speed N24 is decreased initially from the rated speed N24 r to the waiting speed N24 w, then decreased until the pressure P21 reaches the specified pressure P21 a, and then regulated so as to bring the pressure P21 to the target pressure P21 x, and it is possible to reduce the period to bring the rotational speed N24 from the rated speed N24 r to the speed to be reached corresponding to the target pressure P21 x (t6−t1).
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.
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 N24 r and N25 r (step S221). On receiving process information i2 (step S222), the process controller 6 computes a waiting rotational speed N24 w (lower than the rated speed N24 r) for the booster pump 24 and a waiting rotational speed N25 w (lower than the rated speed N25 r) 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 N24 w and N25 w (step S224).
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 N24 w (step S226A). If the speed N24 of the booster pump 24 has not reached the waiting speed N24 w (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 N24 w (if “YES” in step S226A), the booster pump 24 is kept waiting at the waiting speed N24 w (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.
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 N25 w (step S226B). If the speed N25 of the main pump 25 has not reached the waiting speed N25 w (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 N25 w (if “YES” in step S226B), the main pump 25 is kept waiting at the waiting speed N25 w (step S227B). After step S224, steps S225A to S227A and steps S225B to S227B are performed concurrently with each other.
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 P21 a (higher than the rated pressure P21 r) (for example, 90% of the target pressure P21 x). 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.
The pressure controller 6 determines whether or not the pressure P21 in the process chamber 21 has reached the specified pressure P21 a (step S232). If the pressure P21 has not reached the specified value P21 a (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 P21 a (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) P21 x (higher than the rated pressure P21 r) (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.
The pressure controller 6 determines whether or not the pressure P21 in the process chamber 21 has reached the target value P21 x (step S235). If the pressure P21 has not reached the target pressure P21 x (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 P21 x (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 P21 x (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 P21 x is terminated (step S238).
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.
Before time t1, the booster pump 24 and the main pump 25 are respectively rotating at the rated rotational speed N24 r and N25 r, and the pressure P21 in the process chamber 21 is at the rated pressure P21 r. 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 N24 w, and the main pump 25 starts decelerating to bring the speed N25 of the main pump 25 to the waiting speed N25 w.
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 N25 w, and the main pump 25 starts waiting at the waiting speed N25 w. At time t4, the speed N24 of the booster pump 24 reaches the waiting rotational speed N24 w, and the booster pump 24 starts waiting at the waiting speed N24 w.
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 P21 a (for example, 90% of the target pressure P21 x). At time t7, the pressure P21 in the process chamber 21 reaches the specified pressure P21 a, 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 P21 x. 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 P21 x. The pressure P21 in the process chamber 21 is still kept controlled to the target pressure P21 x, and accordingly the speed N25 of the main pump 25 is regulated to the rotational speed corresponding to the target pressure P21 x. This (the state where the target pressure P21 x 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.
For description of the waiting rotational speed N25 w for the main pump 25 in this sixth operation method, the description of the waiting rotational speed N24 w 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 N24 r” by “rated rotational speed N25 r”, and “waiting rotational speed N24 w” by “waiting rotational speed N25 w”.
For description of the specified pressure P21 a related to the main pump 25 in this sixth operation method, the description of the specified pressure P21 a 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”.
In this sixth operation method, the main pump 25 is decelerated to increase the pressure P21 from the rated pressure P21 r to the specified pressure P21 a (90% of the target pressure), and the deceleration of the main pump 25 is stopped when the pressure P21 reaches the specified pressure P21 a. 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.
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 P21 x, the pressure P21 will not stop increasing immediately after reaching the target pressure P21 x and will overshoot the target pressure P21 x. Therefore, in this operation method, the pressure is increased to the specified pressure P21 a (90% of the target pressure P21 x) 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 P21 x (t8−t6).
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 N24 w and the supply of the power E2 is stopped so that the pump 24 rotates by inertia.
In this sixth operation method, the state where the target pressure P21 x is kept is the pressure condition in the process chamber 21 suitable for the process reaction.
In this operation method, the pressure controller 6 computes the waiting speed N24 w for the booster pump 24 and the waiting speed N25 w 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 N25 w before pressure control to bring the pressure P21 in the process chamber 21 to the target pressure P21 x. 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.
In addition, the waiting speed N25 w 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 P21 x in a short period, and can be prevented from overshooting the target pressure P21 during the pressure increasing process.
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 P21 r of the process chamber 21 and the target pressure P21 x suitable for the process reaction is relatively large, that is, the rated pressure P21 r is a high vacuum (0.1 Torr or less) and the target pressure P21 x is a relatively high vacuum (for example, 1 Torr or more), resulting in a relatively large pressure control range.
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.
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 N25 r (step S241). On receiving process information i2 from the process controller (not shown) (step S242), the process controller 6 computes a waiting rotational speed N25 w 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 N25 w (step S244).
Then, it is determined whether or not the speed N25 of the main pump 25 has reached the waiting speed N25 w (step S245). If the speed N25 of the main pump 25 has not reached the waiting speed N25 w (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 N25 w (if “YES” in step S245), the main pump 25 is kept waiting at the waiting speed N25 w (step S246).
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 PR21 x 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).
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 N25 r (step S250). If the speed N25 of the main pump 25 has not reached the rated speed N25 r (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 PR21 x (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 PR21 x (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 PR21 x (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.
If the rotational speed N25 of the main pump 25 reaches the rated rotational speed N25 r (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 N25 r, and pressure reduction control of the pressure P21 of the process chamber 21 to the target pressure reduction rate PR21 x 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 P21 r (step S255).
The pressure reduction rate is included in the process information i2.
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.
Before time t1, the booster pump 24 is stationary, the main pump 25 is rotating at the rated rotational speed N25 r. 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 N25 w. At time t2, the speed N25 of the main pump 25 reaches the waiting rotational speed N25 w, and the main pump 25 starts waiting at the waiting speed N25 w. 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.
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 PR21 x. That is, the pressure reduction rate PR21 in the process chamber 21 is controlled to the constant target value PR21 x 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.
At time t4, the pressure P21 in the process chamber 21 reaches the rated pressure P21 r 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 P21 r 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 P21 r. At time t7, the speed N24 of the booster pump 24 reaches the rated speed N24 w, and the vacuum evacuation device 2 shifts to rated operation.
The pressure controller 6 computes the waiting speed N25 w 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 N25 w before pressure reduction control to reduce the pressure P21 in the process chamber 21 at the target pressure reduction rate PR21 x. Therefore, it is possible to bring the pressure reduction rate PR21 in the process chamber 21 to a desired value PR21 x 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 N25 w 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 PR21 x in a short period.
Since the pressure reduction (evacuation) is performed at the constant specified pressure reduction rate PR21 x (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.
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.
In this operation method, the state where the pressure reduces at the target pressure reduction rate PR21 x is the pressure condition in the process chamber 21 suitable for the process reaction.
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.
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 P21 x 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.
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.
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 N5 w for the dry pump 5.
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 N25 w for the main pump 25.
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 N5 w for the dry pump 5 and a waiting speed N4 w for the turbo molecular pump 4.
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 N25 r. For each of the blocks B1 to B20, there is stored a waiting speed N24 w for the turbo molecular pump 24.
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 N5 r. For each of the blocks C1 to C10, there is stored a waiting speed N4 w for the turbo molecular pump 4.
Based on the values for the target pressure P21 x 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.
Since an appropriate waiting rotational speed is computed from the values for the target pressure P21 x 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 P21 x in a short period in the first, second, fourth, fifth and sixth operation methods.
With reference to FIG. 20, a method for computing (calculating) the waiting rotational speed N5 w, N25 w 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.
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 N5 w, N25 w for the dry pump 5 and the main pump 25.
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 N5 w, N25 w stored for the determined block is adopted.
A suitable waiting speed N5 w, N25 w 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 PR21 x in a short period.
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.
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)

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 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

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

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 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 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

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

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

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;