Patent Publication Number: US-11396876-B2

Title: Control device, control system, control method, recording medium and machine learning device

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of Japanese Priority Patent Application JP 2018-107889 filed on Jun. 5, 2018, the entire contents of which are incorporated herein by reference. 
     FIELD 
     This technique is related to control device, control system, control method, recording medium and machine learning device. 
     BACKGROUND AND SUMMARY 
     In semiconductor manufacturing devices, vacuum pumps are widely used for evacuating gases used in semiconductor manufacturing processes from the inside of the chamber for the purpose of creating a vacuum environment in the chamber. Displacement type vacuum pumps equipped with Roots type or screw type rotors are known as the vacuum pump. 
     Generally, a displacement type vacuum pump includes a pair of rotors disposed in a casing, and a motor that rotationally drives the rotor. A minute clearance is formed between the pair of rotors and between the rotors and the inner surface of the casing, and the rotor is configured to rotate in a non-contact manner with the casing. As the pair of rotors synchronously rotates in opposite directions, the gas in the casing is transferred from the suction side to the discharge side, and the gas is exhausted from a chamber or the like connected to the suction port. 
     Gas used for semiconductor manufacturing process, and a substance generated by a chemical reaction of the gas to be used may include some components that solidify or liquefy as the temperature decreases. Normally, the above-described vacuum pump generates compressive heat during the process of transferring gas, so that the vacuum pump in operation is at a high temperature to some extent. In high temperature by compression heat, in the case where the vacuum pump does not have the temperature at which the components in the gas and the product substance solidify or liquefy, the high temperature of the vacuum pump is maintained by external heating of the pump body or heating of the inflowing gas. Even when the gas including the above-mentioned components is exhausted using the vacuum pump, good vacuum evacuation is performed without solidifying or liquefying the components in the gas or the product substance. 
     However, in some semiconductor manufacturing processes, the liquefaction and solidification of the gas to be used or the product substance generated from the gas to be used cannot be prevented in the above-mentioned high temperature of the vacuum pump. When continuing the operation of the vacuum pump in this process, the solidified product (reaction product) accumulates in the gap between the pump rotors and between the pump rotor and the casing. Although there is a gap between the pump rotor and the casing at high temperature during pump operation, the gap may disappear due to the influence of the deposited product in low temperature of the pump after the pump is stopped. In the absence of the gap between the pump rotor and the casing, the pump cannot be activated, and the manufacturing process cannot be activated. Further, when the operation of the vacuum pump is stopped, and the temperature of the vacuum pump gradually decreases, the components included in the gas remaining in the casing may solidify, whereby this solidified product (reaction product) may accumulate in the gap between the rotors or between the rotor and the casing. As deposition of this product progresses, not only is the activation of the vacuum pump obstructed, but also the vacuum pump stops during the manufacturing process because an excessive load is applied to the vacuum pump during operation of the vacuum pump, resulting in significant damage to the manufacturing process. 
     JP 2009-97349 A discloses the operation control device for a vacuum pump having a rotor rotatably disposed in a casing wherein the operation control device includes a rotor control unit that controls the rotation of the rotor, and the rotor control unit has a function of stopping the rotor after rotating the rotor in the normal direction and/or the reverse direction along the predetermined timing pattern when the operation of the vacuum pump is stopped. 
     Even with the technique of JP 2009-97349 A, the solidified or liquefied product in the casing cannot be eliminated completely when the vacuum pump is stopped, and the vacuum pump cannot be activated normally in some cases. For that reason, when the operation of the vacuum pump is restarted from the state where the operation of the vacuum pump is once stopped, but the vacuum pump cannot be activated normally, the operation of the vacuum pump must be stopped again and the vacuum pump must be maintained or replaced. Therefore, the suspension period of the semiconductor manufacturing device is prolonged due to the re-stop of operation of the vacuum pump. In this way, as the semiconductor manufacturing device is suspended for a long period of time due to abnormality derived from the product of the vacuum pump, it is desired to reduce the generation frequency of maintenance or replacement of the vacuum pump. In addition, the exhaust system usually includes a plurality of vacuum pumps, and in this case, it is also desired to identify only the vacuum pump requiring maintenance with a higher probability before performing a reactivation. This is because when only the identified vacuum pump is maintained, and the operation is continued with a vacuum pump other than the identified vacuum pump, the possibility of continuing the operation is increased as a whole system without adversely affecting the entire exhaust system after the start of operation. 
     It is desirable to provide a control device, a control system, a control method, a recording medium, and a machine learning device that can reduce the generation frequency of maintenance or replacement of a vacuum pump. 
     A control device according to one embodiment, the control device that controls a target vacuum pump including a motor, the control device comprising: a decision unit that decides, using at least one of target state quantities at a time of a past stop process of the target vacuum pump or another vacuum pump wherein the target state quantities are state quantities which fluctuate in accordance with a load at a time of a process of stopping a vacuum pump, a normal fluctuation range or a normal time fluctuation behavior of the target state quantity at the time of the stop process; and a control unit that controls the motor, wherein the control unit compares the target state quantity at the time of the process of stopping the target vacuum pump with the normal fluctuation range or the normal time fluctuation behavior, and changes a method of controlling the motor during the stop process depending on the comparison result. 
     A control system according to one embodiment, the control system that controls a target vacuum pump including a motor, the control system comprising: a decision unit that decides, using at least one of target state quantities at a time of a past stop process of the target vacuum pump or another vacuum pump wherein the target state quantities are state quantities which fluctuate in accordance with a load at a time of a process of stopping a vacuum pump, a normal fluctuation range or a normal time fluctuation behavior of the target state quantity at the time of the stop process; and a control unit that controls the motor, wherein the control unit compares the target state quantity at the time of the process of stopping the target vacuum pump with the normal fluctuation range or the normal time fluctuation behavior, and changes a method of controlling the motor during the stop process depending on the comparison result. 
     A control method according to one embodiment, the control method of controlling a target vacuum pump including a motor, the control method comprising: determining, using at least one of target state quantities at a time of a past stop process of the target vacuum pump or another vacuum pump wherein the target state quantities are state quantities which fluctuate in accordance with a load at a time of a process of stopping a vacuum pump, a normal fluctuation range or a normal time fluctuation behavior of the target state quantity at the time of the stop process; and controlling the motor, wherein the controlling includes comparing the target state quantity at the time of the process of stopping the target vacuum pump with the normal fluctuation range or the normal time fluctuation behavior, and changing a method of controlling the motor during the stop process depending on the comparison result. 
     A non-transitory computer readable recording medium according to one embodiment, the non-transitory computer readable recording medium storing a program, the program causing a control device that controls a target vacuum pump including a motor to function as: a decision unit that decides, using at least one of target state quantities at a time of a past stop process of the target vacuum pump or another vacuum pump wherein the target state quantities are state quantities which fluctuate in accordance with a load at a time of a process of stopping a vacuum pump, a normal fluctuation range or a normal time fluctuation behavior of the target state quantity at the time of the stop process; and a control unit comparing the target state quantity at the time of the process of stopping the target vacuum pump with the normal fluctuation range or the normal time fluctuation behavior, and changes a method of controlling the motor during the stop process depending on the comparison result. 
     A machine learning device according to one aspect of this technique, the machine learning device for learning a method of controlling, in an exhaust system having a plurality of vacuum pumps, at least one motor of the vacuum pumps, the machine learning device comprising: a state measurement unit that measures a target state quantity which is a state quantity which fluctuates in accordance with a time of a process of stopping a vacuum pump in the vacuum pump under execution of a stop process; a storage unit that stores a pump stop control pattern of a target state quantity at a time of a process of stopping the target vacuum pump or another vacuum pump; and a processor, wherein the processor functions as a decision unit that decides, using at least one of target state quantity data at a past stop process of the target vacuum pump or another vacuum pump read from the storage unit, a normal fluctuation range or a normal time fluctuation behavior of the target state quantity at the time of the stop process, a learning unit that controls a motor of the target vacuum pump, compares the target state quantity at the time of the process of stopping the target vacuum pump with the normal fluctuation range or the normal time fluctuation behavior, updates the normal fluctuation range or the normal time fluctuation behavior of the target state quantity at the time of the stop process to store the updated data in the storage unit when it is determined that there is no deviation after determining presence or absence of a deviation from the normal fluctuation range of the target state quantity at the time of the process of stopping the target vacuum pump, and updates a method of controlling the motor at the time of the stop process in accordance with the deviation degree when it is determined that there is a deviation, and a reward calculation unit that calculates a reward for a result of updating a method of controlling the motor at the time of the stop process based on a measured target state quantity, wherein the target state quantity includes at least one of a driving current of a motor included in the at least one vacuum pump, electric power of the motor, a rotation number of a rotor, a temperature of the vacuum pump measured by a temperature sensor, a pressure in the vacuum pump measured by a pressure sensor, and a vibration frequency of the vacuum pump measured by a vibrometer, and wherein the learning unit learns a method of controlling at least one motor of the vacuum pump so that the reward is improved by repeating the update of the method of controlling the motor. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a schematic configuration diagram of a semiconductor manufacturing system  10  according to the present embodiment; 
         FIG. 2  is a schematic functional configuration diagram of a vacuum pump  3  according to the present embodiment; 
         FIG. 3  is a block diagram showing a schematic configuration of a control device  4  according to the present embodiment; 
         FIG. 4  is a diagram showing a first example of a pump stop control pattern by a control device; 
         FIG. 5  is a diagram showing a second example of a pump stop control pattern by a control device; 
         FIG. 6  is a schematic diagram in which a normal fluctuation range and current data in a stop process are compared; 
         FIG. 7  is a schematic diagram showing a temporal change in an amount deviating from a normal fluctuation range; 
         FIG. 8  is a flowchart showing an example of control of a motor during a stop process; 
         FIG. 9  is a diagram showing an example of changing the ON period of a motor  33  during the stop process; 
         FIG. 10  is a schematic configuration diagram of a semiconductor manufacturing system  10   b  in accordance with a modification; 
         FIG. 11  is a block diagram showing a schematic configuration of a control device  4   b  in accordance with a modification; 
         FIG. 12  is a block diagram showing a schematic configuration of an information processing device  5  in accordance with a modification; and 
         FIG. 13  is a block diagram showing a schematic configuration of a machine learning device according to another embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, each embodiment will be described with reference to the drawings. However, detailed explanation more than necessary may be omitted. For example, detailed explanations of already well-known matters and redundant explanation on substantially the same configuration may be omitted. This is to avoid the unnecessary redundancy of the following description and to facilitate understanding by those skilled in the art. The entire contents of U.S. Pat. Nos. 8,172,544 and 9,956,524 are incorporated herein by reference. 
     A control device according to a 1st aspect of one embodiment, the control device that controls a target vacuum pump including a motor, the control device comprising: a decision unit that decides, using at least one of target state quantities at a time of a past stop process of the target vacuum pump or another vacuum pump wherein the target state quantities are state quantities which fluctuate in accordance with a load at a time of a process of stopping a vacuum pump, a normal fluctuation range or a normal time fluctuation behavior of the target state quantity at the time of the stop process; and a control unit that controls the motor, wherein the control unit compares the target state quantity at the time of the process of stopping the target vacuum pump with the normal fluctuation range or the normal time fluctuation behavior, and changes a method of controlling the motor during the stop process depending on the comparison result. 
     In accordance with this configuration, the method of controlling the motor during the stop process is changed, and the reaction product deposited in the gap between the rotors or between the rotor and the casing can be dropped. In this way, since the probability of reactivating the vacuum pump can be increased, it is possible to reduce the generation frequency of maintenance or replacement of the vacuum pump. As a result, the cost for maintenance or replacement of the vacuum pump can be reduced. 
     A control device according to a 2nd aspect of one embodiment, the control device according to the 1st aspect, wherein the control unit changes the method of controlling the motor during the stop process in accordance with a degree of separation from the normal fluctuation range as the comparison result with respect to the target state quantity at the time of the process of stopping the target vacuum pump. 
     In accordance with this configuration, the reaction product deposited in the gap between the rotors or between the rotor and the casing can be dropped by changing the method of controlling the motor during the stop process in accordance with the degree of separation from the normal fluctuation range. In this way, since the probability of reactivating the vacuum pump can be increased, it is possible to reduce the generation frequency of maintenance or replacement of the vacuum pump. 
     A control device according to a 3rd aspect of one embodiment, the control device according to the 1st or 2nd aspect, wherein the control unit changes the method of controlling the motor during the stop process in accordance with an amount of change in a degree of separation from the normal fluctuation range as the comparison result, with respect to the target state quantity at the time of the process of stopping the target vacuum pump. 
     In accordance with this configuration, the reaction product deposited in the gap between the rotors or between the rotor and the casing can be dropped by changing the method of controlling the motor during the stop process in accordance with the amount of change in the degree of separation from the normal fluctuation range. In this way, since the probability of reactivating the vacuum pump can be increased, it is possible to reduce the generation frequency of maintenance or replacement of the vacuum pump. 
     A control device according to a 4th aspect of one embodiment, the control device according to any one of the 1st to 3rd aspect, wherein the control unit changes the method of controlling the motor during the stop process in accordance with the number of times or a frequency of a deviation from the normal fluctuation range as the comparison result with respect to the target state quantity at the time of the process of stopping the target vacuum pump. 
     In accordance with this configuration, the reaction product deposited in the gap between the rotors or between the rotor and the casing can be dropped by changing the method of controlling the motor during the stop process in accordance with the number of times or frequency of a deviation from the normal fluctuation range. In this way, since the probability of reactivating the vacuum pump can be increased, it is possible to reduce the generation frequency of maintenance or replacement of the vacuum pump. 
     A control device according to a 5th aspect of one embodiment, the control device according to any one of the 1st to 4th aspect, wherein the control unit changes the method of controlling the motor during the stop process in accordance with a change in a frequency of a deviation from the normal fluctuation range as the comparison result with respect to the target state quantity at the time of the process of slopping the target vacuum pump. 
     In accordance with this configuration, the reaction product deposited in the gap between the rotors or between the rotor and the casing can be dropped by changing the method of controlling the motor during the stop process in accordance with the change in the frequency of a deviation from the normal fluctuation range. In this way, since the probability of reactivating the vacuum pump can be increased, it is possible to reduce the generation frequency of maintenance or replacement of the vacuum pump. 
     A control device according to a 6th aspect of one embodiment, the control device according to any one of the 1st to 5th aspect, wherein changing the method of controlling the motor during the stop process includes changing an output of the motor during the stop process. 
     In accordance with this configuration, when the target state quantity at the time of the process of stopping the target vacuum pump is abnormal as compared with the normal fluctuation range or the normal time fluctuation behavior, the reaction product deposited in the gap between the rotors or between the rotor and the casing can be dropped by changing the output of the motor during the stop process. In this way, since the probability of reactivating the vacuum pump can be increased, it is possible to reduce the generation frequency of maintenance or replacement of the vacuum pump. 
     A control device according to a 7th aspect of one embodiment, the control device according to any one of the 1st to 5th aspect, wherein changing the method of controlling the motor during the stop process includes changing an ON period and/or an OFF period of the motor during the step process. 
     In this way, when the target state quantity at the time of the process of stopping the target vacuum pump is abnormal as compared with the normal fluctuation range or the normal time fluctuation behavior, the reaction product deposited in the gap between the rotors or between the rotor and the casing can be dropped by changing the of ON and/or OFF period of the motor during the stop process. In this way, since the probability of reactivating the vacuum pump can be increased, it is possible to reduce the generation frequency of maintenance or replacement, of the vacuum pump. 
     A control device according to a 8th aspect of one embodiment, the control device according to any one of the 1st to 5th aspect, wherein changing the method of controlling the motor during the stop process includes changing a rotation direction of the motor during the stop process. 
     In accordance with this configuration, when the target state quantity at the time of the process of stopping the target vacuum pump is abnormal as compared with the normal fluctuation range or the normal time fluctuation behavior, the reaction product deposited in the gap between the rotors or between the rotor and the casing can be dropped by changing the direction of rotation of the motor during the stop process. In this way, since the probability of reactivating the vacuum pump can be increased, it is possible to reduce the generation frequency of maintenance or replacement of the vacuum pump. 
     A control device according to a 9th aspect of one embodiment, the control device according to any one of the 1st to 8th aspect, further comprising a determination unit determining whether reactivation after an operation of the vacuum pump is stopped is possible by comparing the target state quantity at the time of the stop process of the target vacuum pump with the normal fluctuation range or the normal time fluctuation behavior. 
     In accordance with this configuration, since the user of the vacuum pump  3  can determine whether reactivation after the operation of the vacuum pump  3  is stopped is possible before the reactivation is started, the probability of stopping again after the reactivation is started is reduced. In this way, it is possible to suppress the occurrence of a situation in which the suspension period of the semiconductor manufacturing device is prolonged due to abnormality derived from the product of the vacuum pump. 
     A control system according to a 10th aspect of one embodiment, the control system that controls a target vacuum pump including a motor, the control system comprising: a decision unit that decides, using at least one of target state quantities at a time of a past stop process of the target vacuum pump or another vacuum pump wherein the target state quantities are state quantities which fluctuate in accordance with a load at a time of a process of stopping a vacuum pump, a normal fluctuation range or a normal time fluctuation behavior of the target state quantity at the time of the stop process; and a control unit that controls the motor, wherein the control unit compares the target state quantity at the time of the process of stopping the target vacuum pump with the normal fluctuation range or the normal time fluctuation behavior, and changes a method of controlling the motor during the stop process depending on the comparison result. 
     In accordance with this configuration, the method of controlling the motor during the stop process is changed, and the reaction product deposited in the gap between the rotors or between the rotor and the casing can be dropped. In this way, since the probability of reactivating the vacuum pump can be increased, it is possible to reduce the generation frequency of maintenance or replacement of the vacuum pump. As a result, the cost for maintenance or replacement of the vacuum pump can be reduced. 
     A control method according to an 11th aspect of one embodiment, the control method of controlling a target vacuum pump including a motor, the control method comprising: determining, using at least one of target state quantities at a time of a past stop process of the target vacuum pump or another vacuum pump wherein the target state quantities are state quantities which fluctuate in accordance with a load at a time of a process of stopping a vacuum pump, a normal fluctuation range or a normal time fluctuation behavior of the target state quantity at the time of the stop process; and controlling the motor, wherein the controlling includes comparing the target state quantity at the time of the process of stopping the target vacuum pump with the normal fluctuation range or the normal time fluctuation behavior, and changing a method of controlling the motor during the stop process depending on the comparison result. 
     In accordance with this configuration, the method of controlling the motor during the stop process is changed, and the reaction product deposited in the gap between the rotors or between the rotor and the casing can be dropped. In this way, since the probability of reactivating the vacuum pump can be increased, it is possible to reduce the generation frequency of maintenance or replacement of the vacuum pump. As a result, the cost for maintenance or replacement of the vacuum pump can be reduced. 
     A non-transitory computer readable recording medium according to a 12th aspect of one embodiment, the non-transitory computer readable recording medium storing a program, the program causing a control device that controls a target vacuum pump including a motor to function as: a decision unit that decides, using at least one of target state quantities at a time of a past stop process of the target vacuum pump or another vacuum pump wherein the target state quantities are state quantities which fluctuate in accordance with a load at a time of a process of stopping a vacuum pump, a normal fluctuation range or a normal time fluctuation behavior of the target state quantity at the time of the stop process; and a control unit comparing the target state quantity at the time of the process of stopping the target vacuum pump with the normal fluctuation range or the normal time fluctuation behavior, and changes a method of controlling the motor during the stop process depending on the comparison result. 
     In accordance with this configuration, the method of controlling the motor during the stop process is changed, and the reaction product deposited in the gap between the rotors or between the rotor and the casing can be dropped. In this way, since the probability of reactivating the vacuum pump can be increased, it is possible to reduce the generation frequency of maintenance or replacement of the vacuum pump. As a result, the cost for maintenance or replacement of the vacuum pump can be reduced. 
     A machine learning device according to a 13th aspect of one embodiment, the machine learning device for learning a method of controlling, in an exhaust system having a plurality of vacuum pumps, at least one motor of the vacuum pumps, the machine learning device comprising: a state measurement unit that measures a target state quantity which is a state quantity which fluctuates in accordance with a time of a process of stopping a vacuum pump in the vacuum pump under execution of a stop process; a storage unit that stores a pump stop control pattern of a target state quantity at a time of a process of stopping the target vacuum pump or another vacuum pump; and a processor, wherein the processor functions as a decision unit that decides, using at least one of target state quantity data at a past stop process of the target vacuum pump or another vacuum pump read from the storage unit, a normal fluctuation range or a normal time fluctuation behavior of the target state quantity at the time of the stop process, a learning unit that controls a motor of the target vacuum pump, compares the target state quantity at the time of the process of stopping the target vacuum pump with the normal fluctuation range or the normal time fluctuation behavior, updates the normal fluctuation range or the normal time fluctuation behavior of the target state quantity at the time of the stop process to store the updated data in the storage unit when it is determined that there is no deviation after determining presence or absence of a deviation from the normal fluctuation range of the target state quantity at the time of the process of stopping the target vacuum pump, and updates a method of controlling the motor at the time of the stop process in accordance with the deviation degree when it is determined that there is a deviation, and a reward calculation unit that calculates a reward for a result of updating a method of controlling the motor at the time of the stop process based on a measured target state quantity, wherein the target state quantity includes at least one of a driving current of a motor included in the at least one vacuum pump, electric power of the motor, a rotation number of a rotor, a temperature of the vacuum pump measured by a temperature sensor, a pressure in the vacuum pump measured by a pressure sensor, and a vibration frequency of the vacuum pump measured by a vibrometer, and wherein the learning unit learns a method of controlling at least one motor of the vacuum pump so that the reward is improved by repeating the update of the method of controlling the motor. 
     In accordance with this configuration, since the reactivation probability is improved by automatically learning the method of controlling the motor, algorithm development time and cost can be reduced. 
     It is conceivable to change the method of controlling the motor of the vacuum pump during the step process by using the state quantity at the time of the process of stopping the vacuum pump in order to reduce the generation frequency of maintenance or replacement of the vacuum pump. In this case, there is a new problem that it is difficult to distinguish the fluctuation (normal fluctuation) in which the pump can be reactivated, the fluctuation in the state quantity (abnormal fluctuation) that cannot be reactivated, and the fluctuation of state quantity (normal fluctuation) due to other factors from the fluctuation of the state quantity derived from the solidified or liquefied product in the vacuum pump at the time of the process of stopping the vacuum pump. 
     In response to this problem, the control device according to the present embodiment decides, using at least one of target state quantities at the time of the past stop process of the target vacuum pump or another vacuum pump wherein the target state quantities are state quantities that fluctuate in accordance with the time of the process of stopping the vacuum pump, the normal fluctuation range or the normal time fluctuation behavior of the target state quantity at the time of the stop process. The control device according to the present embodiment compares the target state quantity at the time of the process of stopping the target vacuum pump with the normal fluctuation range or the normal time fluctuation behavior of the target state quantity at the time of the stop process. The control device changes the method of controlling the motor during the stop process in accordance with the comparison result. 
       FIG. 1  is a schematic configuration diagram of a semiconductor manufacturing system  10  according to the present embodiment. As shown in  FIG. 1 , the semiconductor manufacturing system  10  according to the present embodiment includes a semiconductor manufacturing device  1 , a vacuum pump  3 , a pipe  2  connecting the semiconductor manufacturing device  1  and the vacuum pump  3 , a control device  4  connected to the vacuum pump  3 , and a display device  6  connected to the control device  4 . The semiconductor manufacturing device  1  includes a chamber film forming furnace  11 , and a control unit  12  that controls the chamber film forming furnace  11 . The chamber film forming furnace  11  and the vacuum pump  3  communicate with each other via the pipe  2 , and the gas in the chamber film forming furnace  11  is discharged and is substantially sucked in vacuum by operating the vacuum pump  3 . The control device  4  controls the operation of the vacuum pump  3 . The control device  4  causes the display device  6  to display information (for example, a determination result as to whether reactivation after the operation of the vacuum pump is stopped is possible). 
       FIG. 2  is a schematic functional configuration diagram of the vacuum pump  3  according to the present embodiment. As shown in  FIG. 2 , the vacuum pump  3  includes a power supply  38 , an inverter  39  whose input is connected to the power supply  38 , a motor  33  whose input is connected to the output of the inverter  39 , and a rotor  31  connected to the rotation shaft of the motor  33 . Further, the vacuum pump  3  includes a pressure gauge  61  and a thermometer  62 . 
     As shown in  FIG. 2 , a rotation number signal indicating the rotation number of the motor  33  is supplied from the motor  33  to the inverter  39 . The current effective value of the driving current and the rotation speed of the motor  33  obtained from the rotation number signal are supplied from the inverter  39  to the control device  4 . In addition, a pressure signal indicating the pressure value in the vacuum pump  3  measured by the pressure gauge  61  is supplied to the control device  4 . In addition, a temperature signal indicating the temperature measured by the thermometer  62  is supplied to the control device  4 . 
     In addition, a vibration sensor that detects the vibration of the vacuum pump  3 , a displacement sensor that detects the displacement of the vacuum pump  3 , and an acceleration sensor that detects the acceleration of the vacuum pump  3  are installed, and output values of the respective sensors may be supplied to the control device  4 . 
     The inverter  39  frequency-converts the alternating current supplied from the power supply  38 , and supplies the driving current obtained by the frequency conversion to the motor  33 . In this way, the rotation shaft of the motor  33  is rotated by the driving current, and as the rotor  31  rotates accordingly, the gas sucked from the pipe  2  is discharged to the outside of the vacuum pump  3  as the rotor  31  rotates. 
     In the vacuum pump  3  having the above configuration, the gas sucked from the suction port (not shown) is transferred to the exhaust side in accordance with the rotors  31 , and is exhausted from the exhaust port not shown) by driving the motor  33  to rotate a pair of rotors  31 . As the gas is continuously transferred from the suction side to the exhaust side, the gas in the chamber film forming furnace  11  connected to the suction port is evacuated. 
     The rotor  31  of the vacuum pump according to the present embodiment is, for example, a Roots type. The vacuum pump  3  may be provided with a screw rotor. Further, the vacuum pump  3  may be a claw or scroll vacuum pump. Further, although the vacuum pump  3  according to the present embodiment is a multi-stage pump as an example, the present invention is not limited to this, and a single stage pump may be used. 
     When the control device  4  stops the operation of the target vacuum pump  3 , the control device  4  controls the rotation of the rotor so as to perform the stop process. Here, the stop process is a process of stopping the rotor  31  after rotating the rotor  31  in the normal direction and/or the reverse direction after starting the pump stop. 
       FIG. 3  is a block diagram showing a schematic configuration of the control device  4  according to the present embodiment. As shown in  FIG. 3 , the control device  4  includes an input unit  41 , an output unit  42 , a storage unit  43 , a memory  44 , and a processor  45 . 
     The input unit  41  is connected to the inverter  39  and the pressure gauge  61 , and the current effective value of the driving current, the rotation speed of the motor  33 , and the pressure value in the vacuum pump  3  are input to the input unit  41 . The output unit  42  outputs information in accordance with a command from the processor  45 . A program to be executed by the processor  45  is stored in the storage unit  43 . The memory  44  temporarily stores information. The processor  45  reads out and executes the program stored in the storage unit  43 . In this way, a CPU (Central Processing Unit)  55  functions as a control unit  451  that controls the motor  33 , a decision unit  452 , and a determination unit  453 . 
       FIG. 4  is a diagram showing a first example of the pump stop control pattern by the control device. As shown in  FIG. 4 , in the first example of  FIG. 4 , the rotation of the rotor  31  in the normal direction and/or the reverse direction is performed along a predetermined timing pattern in the stop process. 
     For example, the storage unit  43  of the control device  4 , as shown in  FIG. 3 , stores a pump stop control pattern (timing pattern for controlling the pump stop) for turning ON and OFF the vacuum pump with the lapse of time when an operation stop switch (not shown) is operated by the operator and operation stop of the vacuum pump is started. 
     When a stop start signal is generated in the vacuum pump, using a timer (not shown) built in the control unit  451 , ON/OFF of the vacuum pump according to the stop pattern of  FIG. 4  is performed, that is, a pump stop control pattern is performed to repeat the operation of turning OFF the vacuum pump for the time t 1  and turning ON the vacuum pump for the time t 2  so that the pump is turned OFF until the time t 1  has elapsed from the start of the pump stop, and the pump is turned ON until the time t 2  elapses after the elapse of the time t 1 . As a result, the rotor  31  is rotated and stopped. In the present embodiment, a pattern of the timer is set so that the rotor  31  is driven in the order of normal rotation (rotation in the normal direction), stop, and normal rotation. 
     When the rotors  31  rotate in the normal direction, one of the rotors  31  rotates in a certain direction (for example, clockwise) and the other rotate rotates in the opposite direction (for example, counterclockwise). In this case, the gas is sucked into the casing from the suction port and transferred to the exhaust port, and then, it is discharged from the exhaust port. That is, the rotation in the normal direction of the rotor  31  means the rotation of the rotor  31  in such a direction that the gas in the casing  32  is transferred from the suction port toward the exhaust port. 
     As described above, when the vacuum pump  3  is stopped, the vacuum pump  3  is once operated after stopping the rotor  31 , and the rotor  31  is rotated again so that the force of the rotor  31  can be applied to the product deposited for example, between the rotor  31  and the casing  32  when the temperature of the vacuum pump lowers. As a result, it is possible to prevent the product from biting due to shrinkage, and since the product is removed, it is possible to smoothly start up the vacuum pump  3 . It is possible to more reliably remove the product by setting a pattern that repeats the rotating and stopping motions of the rotor  31  several times. After the vacuum pump starts normally, the rotor  31  rotates in the normal direction in the steady state, and the gas is exhausted. 
       FIG. 5  is a diagram showing a second example of the pump stop control pattern by the control device. As shown in  FIG. 5 , in the second example of  FIG. 5 , the stop process includes stopping the vacuum pump  3  until the temperature of the vacuum pump  3  drops by a predetermined temperature, and thereafter operating the vacuum pump. As shown in  FIG. 5 , after the initial stop of the vacuum pump  3 , the vacuum pump  3  is activated (ON) for a prescribed time (30 seconds in this example) thereby promoting the removal of product in the vacuum pump  3 . Subsequently, the vacuum pump  3  is stopped (turned OFF) until the temperature measured by the thermometer  62  (that is, the temperature in the vacuum pump  3 ) decreases by a predetermined temperature ΔT (here, 10 degrees, for example). Thereafter, when the temperature inside the vacuum pump  3  measured by the thermometer  62  drops by 10 degrees, the vacuum pump  3  is turned ON again for a prescribed time (30 seconds in this example), and then stops (OFF) again until the temperature measured by the thermometer  62  further decreases by 10 degrees. This cycle is repeated until either the temperature measured by the thermometer  62  reaches a prescribed temperature or the time elapsed from the start of the sequence reaches a prescribed time. 
       FIG. 6  is a schematic diagram comparing the normal fluctuation range with the current data in the stop process. As described with reference to  FIG. 4 , in the stop process, the operation of turning OFF the vacuum pump for the time t 1  and turning ON the vacuum pump for the time t 2  is repeated. The normal fluctuation ranges R 1  and R 2  of the current effective value of the driving current of the motor  33  for the time t 2  during which the vacuum pump is turned ON are shown in the graph on the left side of  FIG. 6 . On the other hand, temporal change of the current effective value of the driving current of the motor  33  during the current stop process is shown in the graph on the right side of  FIG. 6 . When the temporal change in the current effective value for the time t 2  during which the vacuum pump is turned ON during the current stop process is within the normal fluctuation ranges R 1  and R 2 , it can be determined that the temporal change is normal. 
     As an example, the decision unit  452  according to the present embodiment decides, using at least one of target state quantities at the time of the past stop process of the target vacuum pump  3  wherein the target state quantities (for example, the current effective value of the driving current) are state quantities that fluctuate in accordance with the load at she time of stopping the vacuum pump  3 , the normal fluctuation range or the normal time fluctuation behavior of the target state quantity at the time of the stop process. Here, the state quantity is the state quantity of the vacuum pump  3 , the target state quantity includes, for example, the driving current of the motor included in the vacuum pump, the electric power of the motor, the rotation number of the rotor, the temperature of the vacuum pump, the pressure in the vacuum pump, the vibration frequency of the vacuum pump, and these measured values are used. 
     After the target vacuum pump  3  is activated, the decision unit  452  decides, based on the target state quantity at the time of the stop process for the prescribed number of times (for example, 10 times), the normal fluctuation range or the normal time fluctuation behavior of the target state quantity at the time of the stop process. 
     The control unit  451  compares the target state quantity at the time of the process of stopping the target vacuum pump with the normal fluctuation range or the normal time fluctuation behavior, and changes the method of controlling the motor  33  during the stop process depending on the comparison result. In the present embodiment, as an example, the normal fluctuation range is a fluctuation range of the temporal change of the target state quantity at the time of the normal state in the stop process, and as shown in  FIG. 6 , the control unit  451  compares the temporal change of the target state quantity at the time of the stop process of the target vacuum pump  3 , with the fluctuation range of the temporal change of the target state quantity at the time of the normal state in the stop process. 
     The determination unit  453  compares the target state quantity at the time of the stop process of the target vacuum pump  3  with the normal fluctuation range or the normal time fluctuation behavior, thereby determining whether reactivation after the operation of the vacuum pump  3  is stopped is possible. In the present embodiment, as an example, as shown in  FIG. 6 , the determination unit  453  compares the temporal change of the target state quantity at the time of the stop process of the target vacuum pump  3 , with the fluctuation range of the temporal change of the target state quantity at the time of the normal state in the stop process. 
     In the example of  FIG. 6 , for example, the determination unit  453  compares the normal fluctuation range R 1  of  FIG. 6  with the temporal change of the current effective value of the driving current at the time of the stop process. In a case where the temporal change of the current effective value of the driving current at the current stop process falls within this normal fluctuation range R 1 , it is determined that reactivation after the operation of the vacuum pump  3  is stopped is possible, and in a case where the temporal change of the current effective value of the driving current at the current stop process does not fail within this normal fluctuation range R 1 , it is determined that reactivation after the operation of het vacuum pump  3  is stopped is not possible. 
     In accordance with this configuration, it is possible to improve the accuracy of determining whether reactivation after the operation of the vacuum pump  3  is stopped is possible by comparing the temporal change of the target state quantity at time of the process of stopping the target vacuum pump with the fluctuation range of the temporal change of the target state quantity at the time of the normal state in the stop process. 
     On this occasion, for example, when the target state quantity at the time of the stop process deviates from the normal fluctuation range or the normal time fluctuation behavior, the determination unit  453  may output, to the display device  6 , a determination result indicating that reactivation after the operation of the vacuum pump  3  is stopped is not possible. For this reason, since the user of the vacuum pump  3  can determine whether reactivation after the operation of the vacuum pump  3  is stopped is possible before the reactivation is started, the probability of stopping again after the reactivation is started is reduced. In this way, it is possible to suppress the occurrence of a situation in which the suspension period of the semiconductor manufacturing device is prolonged due to abnormality derived from the product of the vacuum pump. 
       FIG. 7  is a schematic diagram showing a temporal change of an amount deviating from the normal fluctuation range. In  FIG. 7 , the amount of a deviation from the normal fluctuation range at time t 3  is d 1 , and the amount of a deviation from the normal fluctuation range at time t 4  is d 2 . 
     For example, when the inclination θ of the line segment L 1  from the point P 1  to the point P 2  exceeds the threshold angle, the control unit  451  may change the method of controlling the motor  33  during the stop process (for example, the motor output may be increased). Alternatively, when (d 2 −d 1 ) exceeds the threshold change amount, the control unit  451  may change the method of controlling the motor  33  daring the stop process (for example, the motor output may be increased). Alternatively, when the amount of change (d 2 −d 1 )/(t 4 −t 3 ) of the amount of a deviation from the normal fluctuation range per unit time exceeds the threshold change rate, the control unit  451  may change the method of controlling the motor  33  during the stop process (for example, the motor output may be increased). 
     In this way, the control unit  451  may change the method of controlling the motor during the stop process in accordance with the amount of change in the degree of separation from the normal fluctuation range with respect to the target state quantity at the time of the process of stopping the target vacuum pump. 
       FIG. 8  is a flowchart showing an example of control of the motor during the stop process. 
     (Step S 101 ) First, the processor  45  of the control device  4  collects the effective value of the driving current of the motor  33  at the prescribed period at the time of performing the stop process. 
     (Step S 102 ) Next, the control unit  451  determines whether the degree of separation from the normal fluctuation range of the effective value of the driving current is equal to or greater than the threshold degree. When the degree of separation from the normal fluctuation range of the effective value of the driving current is less than the threshold degree, the process proceeds to step S 104 . Here, the degree of separation from the normal fluctuation range of the effective value of the driving current may be the effective value of the driving current at one time, or may be the effective values of the driving current at a plurality of times. 
     (Step S 103 ) When it is determined in step S 102  that the degree of separation from the normal fluctuation range of the effective value of the driving current is equal to or greater than the threshold degree, the control unit  451  increases the motor output. 
     In this way, the control unit  451  changes the method of controlling the motor  33  during the stop process in accordance with the degree of separation from the normal fluctuation range as a comparison result with respect to the target state quantity at the time of the process of stopping the target vacuum pump. 
     In accordance with this configuration, the reaction product deposited in the gap between the rotors or between the rotor and the casing can be dropped by changing the method of controlling the motor during the stop process in accordance with the degree of separation from the normal fluctuation range. In this way, since the probability of reactivating the vacuum pump can be increased, it is possible to reduce the generation frequency of maintenance or replacement of the vacuum pump. 
     (Step S 104 ) Next, the control unit  451  determines whether the amount of change in the degree of separation from the normal fluctuation range is equal to or greater than the threshold change amount. When the amount of change in the degree of separation from the normal fluctuation range is less than the threshold change amount, the process proceeds to step S 106 . 
     (Step S 105 ) When it is determined in step S 104  that the amount of change in the degree of separation from the normal fluctuation range is equal to or greater than the threshold change amount, the control unit  451  increases the motor output. 
     In this way, the control unit  451  changes the method of controlling the motor  33  during the stop process in accordance with the amount of change in the degree of separation from the normal fluctuation range as a comparison result with respect to the target state quantity at the time of the process of stopping the target vacuum pump. 
     In accordance with this configuration, the reaction product deposited in the gap between the rotors or between the rotor and the casing can be dropped by changing the method of controlling the motor during the stop process in accordance with the amount of change in the degree of separation from the normal fluctuation range. In this way, since the probability of reactivating the vacuum pump can be increased, it is possible to reduce the generation frequency of maintenance or replacement of the vacuum pump. 
     (Step S 106 ) Next, the control unit  451  determines whether the number of times of a deviation from the normal fluctuation range of the effective value of the driving current is equal to or greater than the threshold number of times. When the number of times of a deviation from the normal fluctuation range of the effective value of the driving current is less than the threshold number of times, the process proceeds to step S 108 . 
     (Step S 107 ) When it is determined in step S 106  that the number of times of a deviation from the normal fluctuation range of the effective value of the driving current, is equal to or greater than the threshold number of times, the control unit  451  increases the motor output. 
     Instead of the number of times of a deviation from the normal fluctuation range of the effective value of the driving current, the frequency of a deviation from the normal fluctuation range of the effective value of the driving current may be used. In this way, the control unit  451  changes the method of controlling the motor  33  during the stop process in accordance with the number of times or the frequency of a deviation from the normal fluctuation range as the comparison result with respect to the target state quantity at the time of the process of stopping the target vacuum pump. 
     In accordance with this configuration, the reaction product deposited in the gap between the rotors or between the rotor and the casing can be dropped by changing the method of controlling the motor during the stop process in accordance with the number of times or frequency of a deviation from the normal fluctuation range. In this way, since the probability of reactivating the vacuum pump can be increased, it is possible to reduce the generation frequency of maintenance or replacement of the vacuum pump. 
     (Step S 108 ) Next, the control unit  451  determines whether the index (for example, the change rate, the change amount) representing the change in the frequency of a deviation from the normal fluctuation range of the effective value of the driving current is equal to or greater than the change threshold. When the frequency of a deviation from the normal fluctuation range of the effective value of the driving current is less than the change threshold, the process returns to step S 101 . 
     (Step S 109 ) When it is determined in step S 108  that the index representing the change in the frequency of a deviation from the normal fluctuation range of the effective value of the driving current is equal to or greater than the change threshold, the control unit  451  increases the motor output and the process returns to step S 101 . 
     As described above, the control unit  451  changes the method of controlling the motor during the stop process in accordance with the change in the frequency of a deviation from the normal fluctuation range as the comparison result with respect to the target state quantity at the time of the process of stopping the target vacuum pump. 
     In accordance with this configuration, the reaction product deposited in the gap between the rotors or between the rotor and the casing can be dropped by changing the method of controlling the motor during the stop process in accordance with the change in the frequency of a deviation from the normal fluctuation range. In this way, since the probability of reactivating the vacuum pump can be increased, it is possible to reduce the generation frequency of maintenance or replacement of the vacuum pump. 
     As described above, the control device  4  according to the present embodiment is a control device that controls the target vacuum pump  3  including the motor  33 . The decision unit  452  decides, using at least one of target state quantities at the time of the past stop process of the target vacuum pump or another vacuum pump wherein the target state quantities are state quantities that fluctuate in accordance with the load at the time of the process of stopping the vacuum pump  3 , the normal fluctuation range or the normal time fluctuation behavior of the target state quantity at the time of the stop process. The control unit  451  controls the motor  33 , compares the target state quantity at the time of the process of stopping the target vacuum pump  3  with the normal fluctuation range or a normal time fluctuation behavior, and changes the method of controlling the motor  33  during the stop process depending on the comparison result. 
     With this configuration, the reaction product deposited in the gap between the rotors or between the rotor and the casing can be dropped by changing the method of controlling the motor  33  during the stop process. In this way, since the probability of reactivating the vacuum pump  3  can be increased, it is possible to reduce the generation frequency of maintenance or replacement of the vacuum pump  3 . As a result, the cost for maintenance or replacement of the vacuum pump  3  can be reduced. 
     In the present embodiment, as mentioned above, as an example, it has been described that changing the method of controlling the motor during the stop process includes changing an output of the motor during the stop process. In accordance with this configuration, when the target state quantity at the time of the process of stopping the target vacuum pump is abnormal as compared with the normal fluctuation range or the normal time fluctuation behavior, the reaction product deposited in the cap between the rotors or between the rotor and the casing can be dropped by changing the output of the motor during the stop process. In this way, since the probability of reactivating the vacuum pump can be increased, it is possible to reduce the generation frequency of maintenance or replacement of the vacuum pump. 
     In the present embodiment, as an example, it has been described that the change of the method of controlling the motor during the stop process is to change the output of the motor  33  during the stop process (specifically, for example, to increase the output of the motor), but the present invention is not limited to this. 
     As shown in  FIG. 9 , the change of the method of controlling the motor  33  during the stop process may be to change the on and/or off period of the motor  33  during the stop process. 
       FIG. 9  is a diagram showing an example of changing the ON period of the motor  33  during the stop process. Deviation from the normal fluctuation range is assumed to be the abnormality generation, and in the case of  FIG. 9 , the threshold frequency of the abnormality generation frequency is set to 0.7. In  FIG. 9 , when the abnormality generation frequency reaches 0.7, since the value is equal to or greater than the threshold frequency of the abnormality generation frequency, the control unit  451  prolongs the motor-ON time (time t 2  in  FIG. 4 ) from 100 seconds to 200 seconds. As a result, it is possible to prolong the time to shake off the solidified or liquefied product in the vacuum pump. 
     In this way, when the target state quantity at the time of the process of stopping the target vacuum pump is abnormal as compared with the normal fluctuation range or the normal time fluctuation behavior, the reaction product deposited in the gap between the rotors or between the rotor and the casing can be dropped by changing the of ON and/or OFF period of the motor during the stop process. In this way, since the probability of reactivating the vacuum pump can be increased, it is possible to reduce the generation frequency of maintenance or replacement of the vacuum pump. 
     As shown in  FIG. 9 , when the abnormality generation frequency, which is 0.35, is lower than the threshold frequency after prolonging the motor-ON time to 200 seconds, the control unit  451  may shorten the motor-ON time (time t 2  in  FIG. 4 ) from 200 seconds to 150 seconds. 
     Alternatively, the change of the method of controlling the motor  33  during the stop process may be a change in the rotation direction of the motor  33  during the stop process. For example, the normal rotation and the reverse rotation may be repeated alternately such that the motor is in the normal rotation in a certain motor-ON time and the reverse rotation in the next motor-ON time. 
     In accordance with this configuration, when the target state quantity at the time of the process of stopping the target vacuum pump is abnormal as compared with the normal fluctuation range or the normal time fluctuation behavior, the reaction product deposited in the gap between the rotors or between the rotor and the casing can be dropped by changing the direction of rotation of the motor during the stop process. In this way, since the probability of reactivating the vacuum pump can be increased, it is possible to reduce the generation frequency of maintenance or replacement of the vacuum pump. 
     The above-described target vacuum pump may be a pump in a vacuum evacuation unit in which two pumps are accommodated in one housing. 
     Modification 
     Subsequently, a modification will be described.  FIG. 10  is a schematic configuration diagram of a semiconductor manufacturing system  10   b  according to the modification. As shown in  FIG. 10 , the semiconductor manufacturing system  10   b  includes a control system  7 , and the control system  7  has a control device  4   b , an information processing device  5 , and the display device  6 . 
     In the semiconductor manufacturing system  10   b  according to the modification, the functions of the decision unit  452  and the determination unit  453  included in the control device  4  according to the present embodiment are included in the information processing device  5 . 
       FIG. 11  is a block diagram showing a schematic configuration of the control device  4   b  according to the modification. As shown in  FIG. 11 , in the control device  4   b  according to the modification, as compared with the control device  4  according to the present embodiment, the CPU  45  is changed to the CPU  45   b , and the CPU  45   b  does not function as the decision unit  452  and the determination unit  453 . 
       FIG. 12  is a block diagram showing a schematic configuration of the information processing device  5  according to the modification. As shown in  FIG. 11 , the information processing device  5  includes an input unit  51 , an output unit  52 , a storage unit  53 , a memory  54 , and the CPU (Central Processing Unit)  55 . 
     The input unit  51  is connected to the inverter  39  and the pressure gauge  61 , and the current effective value of the driving current, the rotation speed of the motor  33 , and the pressure value in the vacuum pump  3  are input to the input unit  51 . The output unit  52  outputs information in accordance with a command from the CPU  55 . The storage unit  53  stores a program to be executed by the CPU  55 . The memory  54  temporarily stores information. 
     The CPU  55  functions as a decision unit  552 , and a determination unit  553  by reading the program from the storage unit  53  and executing it. Since the decision unit  552  has the same function as the decision unit  452  included in the control device  4  of the present embodiment, and the determination unit  553  has the same function as the determination unit  453  included in the control device  4  of the present embodiment, a detailed description thereof will be omitted. 
     It is to be noted that the present invention is not limited to the above configuration, and the control system including a plurality of devices may perform the processes of the control device according to the present embodiment or the control device according to the modification, and the information processing device in a distributed manner by the plurality of devices. Further, the above-described various processes related to the control device according to the present embodiment or the information processing device according to the modification may be performed so that a program for executing each processing of the control device according to the present embodiment or the information processing device according to the modification is recorded in a computer readable recording medium, and the program recorded in the recording medium is read by a computer system and executed by the processor. 
     Further, in the present embodiment, the current effective value of the driving current is used as the target state quantity which is a state quantity which fluctuates in accordance with the load at the time of the process of stopping the vacuum pump  3 , but the present invention is not limited to this. For example, the target state quantity may be the driving current of the motor included in the vacuum pump, the electric power of the motor, the rotation number of the rotor, the temperature of the vacuum pump, the pressure in the vacuum pump, the vibration frequency of the vacuum pump, or the like. Also, the target state quantity may be used after filtering the target state quantity with a predetermined filter, or may be used after averaging it. 
     Each processing by the control device according to the present embodiment, or the control device and the information processing device according to the modification is implemented by, for example, artificial intelligence (AI) such as quantum computing, neural network such as deep learning, or machine learning. For example, supervised learning may be performed by using the target state quantity at the time of the past stop process of the target vacuum pump or other vacuum pump as teacher data. 
     The processes of the decision unit  452  and the determination unit  453  according to the present embodiment, or the processing in the information processing device according to the modification may be performed in the cloud, or may be performed from a terminal device (so-called edge) connected to an information processing device such as a server via a communication network. 
     For example, as the edge terminal on which the logic for performing the processing of the decision unit  452  and the determination unit  453  according to the present embodiment, or the processing in the information processing device according to the modification is implemented, the controller applying a fieldbus (a standard for exchanging signals between field devices and controllers operating in factories, etc. using digital communication) according to which communication cart be performed at high speed by open architecture (logical structure of computer system), more specifically, the controller compatible with PLC 5 language or C language in accordance with IEC 61131-3 (the standard defined by the International Electrotechnical Commission (IEC) December 1993, where a programming language for PLC (Programmable Logic Controller) is defined) can be used. 
     Note that the determination unit  553  may have a function of generating a new determination algorithm as to whether reactivation is possible from the comparison result between the target state quantity at the time of the process of stopping the target vacuum pump and the past normal fluctuation range or the past normal time fluctuation behavior, the amount of control of the motor during the stop process, and the reactivation result. 
     Specifically, for example, when reactivation cannot be performed, from the comparison result at this time and the amount of control of the motor during the stop process, it can be recognized that the reactivation is not possible, so that the determination unit  553  updates the determination standard in the determination algorithm. Along with this, the determination unit  553  performs control so as to improve the amount of control of the motor during the stop process so that reactivation can be performed when the same comparison result is given next. In this way, since a new determination algorithm is automatically generated, algorithm development time and cost can be reduced. 
     As shown in  FIG. 13 , a machine learning device for learning a method of controlling, in an exhaust system having at least one vacuum pump, at least one motor of the at least one vacuum pump may be provided. 
       FIG. 13  is a block diagram showing a schematic configuration of a machine learning device according to another embodiment. An exhaust system  70  includes the vacuum pump  3  and a machine learning device  8 . The exhaust system  70  is, for example, a semiconductor manufacturing system as in the present embodiment. 
     As shown in  FIG. 13 , the machine learning device  8  includes a state measurement unit  71 , a storage unit  72 , and a processor  81 . 
     The state measurement unit  71  measures the target state quantity which is a state quantity fluctuating in accordance with the time of the process of stopping the vacuum pump in the vacuum pump during the performance of the stop process. The state measurement unit  71  is, for example, a measurement instrument or a sensor. Specifically, for example, the state measurement unit  71  may be the pressure gauge  61  that measures the pressure value in the vacuum pump  3 , the thermometer  62  that measures the temperature inside the vacuum pump  3 , a vibration sensor that detects the vibration of the vacuum pump  3 , a displacement sensor that detects the displacement of the vacuum pump  3 , or an acceleration sensor that detects the acceleration of the vacuum pump  3 . 
     The storage unit  72  stores the pump stop control pattern of the target state quantity at the time of the process of stopping the target vacuum pump or another vacuum pump. The storage unit  72  stores a program to be executed by the processor  81 . The processor  81  functions as a decision unit  73 , a learning unit  74 , and a reward calculation unit  75  by reading and executing the program from the storage unit  72 . 
     The decision unit  73  uses at least one of the target state quantity data at the time of the past stop process of the target vacuum pump or another vacuum pump read from the storage unit, and decides the normal fluctuation range or the normal time fluctuation behavior of the target state quantity at the time of the stop process. 
     The learning unit  74  controls the motor of the target vacuum pump, and compares the target state quantity at the time of the process of stopping the target vacuum pump of the object with the normal fluctuation range or the normal time fluctuation behavior. When it is determined that there is no deviation after determining presence or absence of a deviation from the normal fluctuation range of the target state quantity at the time of the process of stopping the target vacuum pump, the learning unit  74  updates the normal fluctuation range or the normal time fluctuation behavior of the target state quantity at the time of the stop process to cause the storage unit to store the update data, and when it is determined that there is a deviation the learning unit  74  updates the method of controlling the motor during the stop process in accordance with the degree of deviation. 
     The reward calculation unit  75  calculates, based on the measured target state quantity, a reward for the result of updating the method of controlling the motor during the stop process is calculated. 
     Specifically, for example, when the motor torque at the time of activation exceeds the reference value or when activation is not possible, the reward calculation unit  75  judges the result as abnormal and calculates that there is no reward. On the other hand, for example, when the motor torque at the time of activation does not exceed the reference value and the normal operation is performed, the reward calculation unit  75  calculates that there is a reward and add the set value to the reward. 
     The target state quantity includes at least one of the driving current of the motor included in the at least one vacuum pump, the electric power of the motor, the rotation number of the rotor, the temperature of the vacuum pump measured by the temperature sensor, the pressure in the vacuum pump measured by the pressure sensor, and the vibration frequency of the vacuum pump measured by the vibrometer. 
     The learning unit  74  learns a method of controlling at least one motor of the vacuum pump so that the reward is improved by repeating the update of the method of controlling the motor. In this way, since the method of controlling the motor is automatically learned and the reactivation probability is improved, algorithm development time and cost can be reduced. 
     In addition to the above configuration, the machine learning system including a plurality of devices may perform each process of the machine learning device according to another embodiment in a distributed manner by the plurality of devices. Further, various processes of the processor of the machine learning device according to another embodiment may be performed so that a program for executing each processing of the processor of the machine learning device according to another embodiment is recorded in a computer readable recording medium, and the program recorded in the recording medium is read by a computer system and executed by the processor. 
     As described above, the present invention is not limited to the above embodiment as it is, and the constituent elements can be modified and materialized without departing from the gist thereof in the implementation stage. For example, in another embodiment, a momentum transport pump such as a turbo molecular pump can be used as a vacuum pump. Alternatively, in addition to the vacuum pump employed in the exhaust system for exhausting the gas used in the semiconductor manufacturing process, for example, the embodiment can also be applied to a vacuum pump used for an exhaust system for medical use and analysis equipment. In addition, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the above embodiment. For example, some constituent elements may be deleted from all the constituent elements shown in the embodiment. Further, the constituent elements of different embodiments may be appropriately combined. 
     REFERENCE SIGNS LIST 
     
         
           1  Semiconductor manufacturing device 
           10  Semiconductor manufacturing system 
           11  Chamber film forming furnace 
           12  Control unit 
           2  Pipe 
           3  Vacuum pump 
           31  Rotor 
           32  Casing 
           33  Motor 
           38  Power supply 
           39  Inverter 
           4  Control device 
           41  Input unit 
           42  Output unit 
           43  Storage unit 
           44  Memory 
           45  Processor 
           451  Control unit 
           452  Decision unit 
           453  Determination unit 
           5  Information processing device 
           6  Display device 
           61  Pressure gauge 
           62  Thermometer 
           7  Control system 
           8  Machine learning device 
           70  Exhaust system 
           71  State measurement unit 
           72  Storage unit 
           73  Decision unit 
           74  Learning unit 
           75  Reward calculation unit 
           81  Processor