KR20040054577A - Control apparatus for vacuum pump - Google Patents

Abstract

PURPOSE: A controller of a vacuum pump is provided to improve the durability of the vacuum pump without increase of size and weight by using an ECU(Electrical Control Unit). CONSTITUTION: A vacuum pump(20) includes a pump mechanism(21) for keeping a desired vacuum degree in an exhaust object space, an electromotor(22) for driving the pump mechanism, and a controller. The controller(30) includes an ECU(31) and a current detector(32). The ECU decelerates a rotation speed of the electromotor, when the increment of load torque per a unit time in the electropump rises abruptly. The ECU calculates the load torque of the vacuum pump in reliance on a value of the current supplied for the electromotor. The current value is detected by the current detector.

Description

Control Unit of Vacuum Pump {CONTROL APPARATUS FOR VACUUM PUMP}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control apparatus for a vacuum pump including a pump mechanism portion for exhausting the exhaust target space to a predetermined vacuum degree, and an electric motor portion for driving the pump mechanism portion.

BACKGROUND ART Conventionally, a semiconductor manufacturing apparatus of a type in which a load lock chamber (load lock chamber) is provided in parallel with a process chamber (process chamber) for performing a film forming process or the like of a wafer (substrate) is known (see Patent Document 1, for example).

In this apparatus, wafer exchange between the process chamber and the outside of the semiconductor manufacturing apparatus is performed via this load lock chamber. A vacuum pump for connecting the chamber to a predetermined vacuum degree is connected to the load lock chamber through an opening / closing valve. The on-off valve has a structure in which the load lock chamber and the vacuum pump can be pressurized by operation from the outside or the like.

The exchange of wafers between the load lock chamber and the process chamber at the time of the wafer exchange described above is carried out in a state where the load lock chamber is pressurefully cut off from the outside of the semiconductor manufacturing apparatus and at the same time a predetermined vacuum degree by a vacuum pump. . On the other hand, the exchange of wafers between the load lock chamber and the outside of the semiconductor manufacturing apparatus is carried out with the load lock chamber being pressurefully cut off from the process chamber and at the same time returned to atmospheric pressure.

In the process of performing a wafer exchange operation between the load lock chamber and the outside of the semiconductor manufacturing apparatus, the film forming process and the like are performed in the process chamber which is pressure-blocked with the load lock chamber to improve the work efficiency in semiconductor manufacturing. Can be designed.

In addition, when the load lock chamber in the atmospheric pressure is depressurized again to a predetermined vacuum, the load lock chamber and the vacuum pump are communicated with each other by exhausting the opening / closing valve from the closed state to the open state. At this time, when the on-off valve is switched from the closed state to the open state while the vacuum pump is driven, the inside of the vacuum pump is rapidly boosted to atmospheric pressure at the above-described predetermined degree of vacuum, whereby the pressure load of the vacuum pump (exhaust Pressure load) spikes. In the case where an electric motor is used as the driving source of the vacuum pump, in this vacuum pump, the output torque of the electric motor (that is, the load torque of the vacuum pump) rapidly increases with the increase in the pressure load described above.

In this case, for example, in order to avoid breakage of the constituent members of the vacuum pump due to excessive load torque of the vacuum pump, the electric motor using the control device so that the load torque of the vacuum pump does not exceed a predetermined upper limit value. You can think of controlling it. As this control aspect, what is shown to the time chart of FIG. 2A and FIG. 2B is mentioned, for example. A diagram 91 in FIG. 2A shows a drive frequency when a brushless motor of a synchronous motor type is used as the electric motor. 2B shows a current value of the supply current for the same electric motor. This current value correlates to the magnitude of the output torque of the electric motor, that is, the load torque of the vacuum pump.

As shown in this time chart, when switching from the closed state of the on-off valve to the open state described above at the time point t1 is performed, the current of the supply current to the electric motor is increased according to the sudden increase in the pressure load of the vacuum pump based on these. The value spikes (i.e., the load torque of the vacuum pump spikes).

When it is determined that the electric current value of the electric motor has reached the predetermined upper limit value i2 at the time point t2, the control device sets the drive frequency of the electric motor from the drive frequency fmax of the high speed side (high speed side at the rotational speed of the electric motor). The speed decreases toward the drive frequency fmin on the low speed side. As the rotational speed of the electric motor decreases due to the reduction of the drive frequency, an increase in the pressure load of the vacuum pump is suppressed, and accordingly, the output torque of the electric motor, that is, the load torque of the vacuum pump, becomes a predetermined upper limit value (the upper limit value of the supply current ( The upper limit value of the torque corresponding to i2)) is limited not to exceed.

[Patent Document 1]

Japanese Patent Application Laid-open No. Hei 9-306972 (3rd page, Fig. 1)

However, in the above-described control mode, even though it is possible to avoid the damage of the constituent members of the vacuum pump due to the excessive load torque of the vacuum pump, the load torque at the time of switching from the closed state to the open state of the on-off valve can be avoided. There is a sudden increase (rapid rise). At this time, a large difference occurs in the increase speed of the load torque before and after the start time t1 of the rise. That is, while sudden rise fluctuations in the increase speed of the load torque occur, the state in which the increase speed is large continues until the current value of the electric motor reaches the predetermined upper limit value i2. That is, in the above-described control mode, even if the load torque of the vacuum pump can be avoided from being excessive, the vacuum pump can be continued by the sudden rise fluctuation of the increase speed of the load torque or the state where the increase speed is large after this rise change. There is a fear that the constituent members of the module may be greatly impacted. This causes the structural member to reach breakdown.

Here, in order to avoid the destruction of the constituent member, it is possible to reinforce the constituent member in order to strengthen it, but there is a problem that it leads to the enlargement and weight of the vacuum pump.

It is an object of the present invention to provide a control apparatus for a vacuum pump that can improve the durability of the vacuum pump without causing an increase in size or weight due to the reinforcement of the vacuum pump.

1 is a schematic view of a semiconductor manufacturing apparatus and a vacuum pump.

2A is a time chart showing a drive frequency in the electric motor unit, and FIG. 2B is a time chart showing a current value in the electric motor unit.

3 is a time chart in another example, FIG. 3A is a time chart showing a drive frequency in the electric motor unit, and FIG. 3B is a time chart showing a current value in the electric motor unit.

Explanation of symbols on the main parts of the drawings

11 semiconductor manufacturing apparatus 12 process chamber

13 loadlock chamber as exhaust target space 20 vacuum pump

21 pump mechanism 22 electric motor

30: Interleaver as control device 31: ECU

32: current detector

In order to solve the said problem, the control apparatus of the vacuum pump of Claim 1 implements deceleration control which reduces the rotational speed of an electric motor part, when the increase amount of load torque per unit time of the said vacuum pump rises and changes abruptly.

For example, in the case where the outside air is introduced into the exhaust target space while the vacuum pump is in the operating state and the pressure in the space rapidly increases, the increase in the pressure load (pressure load related to the exhaust air) of the vacuum pump causes the The output torque (i.e. the load torque of the vacuum pump) will tend to rise. In this case, the load torque increase amount per unit time of the vacuum pump (rate of increase of the load torque of the vacuum pump) rises and fluctuates, for example, from a state of almost zero to a state exceeding a certain size, that is, the load per unit time of the vacuum pump The torque increase amount may fluctuate rapidly.

The control apparatus of this invention performs deceleration control which reduces the rotational speed of an electric motor part, when the amount of increase of load torque per unit time of a vacuum pump rises and changes abruptly. Thus, for example, in the case of the rise of the above-mentioned load torque, the sudden rise fluctuation of the load torque increase amount per unit time of the vacuum pump or the state in which the load torque increase amount per unit time of the vacuum pump is large after this rise change is continued, thereby configuring the vacuum pump. It is possible to reduce the impact the member receives. Therefore, for example, in order to improve impact resistance, it is not necessary to reinforce the constituent members of the vacuum pump, and the enlargement and weight of the vacuum pump due to this reinforcement are prevented.

Claim 2 calculates the load torque of the said vacuum pump based on the supply current value to an electric motor part.

According to the present invention, in order to detect the load torque of the vacuum pump, there is no need to provide a torque sensor or the like in particular. Therefore, it can contribute to cost reduction or simplification of structure.

Claim 3 or Claim 3 WHEREIN: The load torque increase amount per unit time of the said vacuum pump is repeatedly monitored for every predetermined time. This monitoring is continued even after determining that the amount of increase in load torque per unit time of the vacuum pump rises and fluctuates rapidly.

According to the present invention, even after the deceleration control is started, the rotational speed of the electric motor unit can be appropriately controlled in accordance with the variation of the load torque increase amount per unit time of the vacuum pump.

The method according to any one of claims 1 to 3, wherein when the load torque increase amount per unit time of the vacuum pump is larger than a predetermined value, it is determined that the load torque increase amount per unit time of the vacuum pump is sharply increased and changed, Take control.

According to the present invention, for example, the deceleration control is performed based on the difference between the load torque increase amount per unit time of the vacuum pump at a predetermined time point and the load torque increase amount at a predetermined time point separate from the predetermined time point. In comparison with this, it is possible to omit the above-described process for calculating the difference. That is, it becomes possible to reduce the processing burden in a control apparatus.

The method according to any one of claims 1 to 3, wherein when the rate of change of the load torque increase amount per unit time of the vacuum pump is larger than a predetermined value, it is determined that the load torque increase amount per unit time of the vacuum pump is sharply increased and changed The deceleration control is performed.

According to the present invention, for example, how much change has been made in a predetermined time with respect to the amount of increase in load torque per unit time of the vacuum pump as compared with the embodiment of deceleration control based on the amount of increase in load torque per unit time of the vacuum pump. Can be identified more accurately. On the other hand, "the change rate of the load torque increase amount per unit time of a vacuum pump" here shows how much the load torque increase amount per unit time of a vacuum pump changed per unit time.

The method according to claim 4 or 5, wherein the deceleration control is carried out to reduce the load torque increase per unit time of the vacuum pump toward a predetermined target value.

According to the present invention, the amount of load torque increase per unit time of the vacuum pump is controlled to approach or coincide toward a predetermined target value. By this control, the load torque increase amount per unit time can be reduced when the load torque of the vacuum pump rises.

The method according to claim 5, wherein the deceleration control is performed to reduce the rate of change of the load torque increase amount per unit time of the vacuum pump toward a predetermined target value.

According to the present invention, the rate of change of the load torque increase amount per unit time of the vacuum pump is controlled to approach or coincide toward a predetermined target value. Therefore, it becomes possible to reduce the impact resulting from the change rate of the load torque increase amount per unit time of a vacuum pump among the impacts which the structural member of a vacuum pump receives.

Claim 8 controls the electric motor part in any one of Claims 1-7 so that the load torque of the said vacuum pump may not exceed predetermined upper limit.

According to the present invention, since the maximum value of the load torque acting on the vacuum pump is limited, it is possible to avoid deformation, breakage, etc. of the constituent members of the vacuum pump due to excessive load torque.

Claim 9 is a brushless motor of any one of Claims 1-8 comprised by the said electric motor part of a synchronous motor type or an induction motor type.

According to this invention, it becomes easy to make an electric motor part high durability compared with the motor with a brush. Further, regardless of the magnitude of the load torque acting on the vacuum pump, the rotational speed of the electric motor portion can be adjusted by adjusting the drive frequency of the supply current. In this case, the driving frequency of the supply current to the electric motor portion is changed (ie, reduced) to the low speed side of the rotational speed of the electric motor portion, whereby the rotational speed of the electric motor is lowered, thereby reducing the pressure load on the vacuum pump, The increase rate of the load torque of the vacuum pump can be lowered.

Claim 10 is a vacuum pump according to any one of claims 1 to 9, wherein the load lock chamber provided in the process chamber in the semiconductor manufacturing apparatus is an exhaust target space.

Since the load lock chamber is, for example, a chamber serving as a relay point when the workpiece is exchanged between the atmospheric pressure space surrounding the semiconductor manufacturing apparatus and the process chamber, the load lock chamber tends to be frequently stepped up to atmospheric pressure at a predetermined degree of vacuum. There is this. That is, in the vacuum pump for evacuating the load lock chamber, a sudden increase in the load torque due to the sudden increase in the pressure load (pressure load related to the exhaust) can be frequently generated. Therefore, in this aspect, it is particularly effective to embody the invention of any one of claims 1 to 9 and to improve the durability of the vacuum pump.

Embodiment of the invention

EMBODIMENT OF THE INVENTION Hereinafter, embodiment which used this invention for the vacuum pump for exhaust of the load lock chamber in a semiconductor manufacturing apparatus is described.

As shown in FIG. 1, in the semiconductor manufacturing apparatus 11, the process chamber 12 is provided in the load lock chamber 13. In the process chamber 12, for example, a film forming process such as a vacuum deposition process or a sputtering process on the wafer is performed. These processes are carried out after bringing the process chamber 12 to a predetermined degree of vacuum using exhaust means, not shown.

The wafer exchange between the outer space (atmospheric pressure space) of the semiconductor manufacturing apparatus 11 and the process chamber 12 is carried out via the load lock chamber 13. That is, a path is formed between the two chambers 12 and 13 for exchanging wafers in the wafer exchange, and a gate valve capable of pressure-contacting between the chambers 12 and 13 in the middle of this path. 14) is formed. In the semiconductor manufacturing apparatus 11, a path is formed between the load lock chamber 13 and the external space of the semiconductor manufacturing apparatus 11 for carrying the wafers back and forth during the wafer exchange. A gate valve 15 capable of pressure-contacting the lock chamber 13 and the external space is formed.

The vacuum pump 20 is connected to the semiconductor manufacturing apparatus 11 via the exhaust path 16. The vacuum pump 30 uses the load lock chamber 13 as an exhaust object space. In the middle of the exhaust path 16, an opening / closing valve 17 capable of pressure-connecting the load lock chamber 13 and the vacuum pump 20 by an operation from the outside or the like is formed.

In addition, the load lock chamber 13 communicates with the external space of the semiconductor manufacturing apparatus 11 through the external air introduction path 18. In the middle of the outside air introduction path 18, an on-off valve 19 capable of pressure-contacting the load lock chamber 13 and the external space by an operation from the outside or the like is formed.

The vacuum pump 20 includes a pump mechanism portion 21 for exhausting the chamber 13 to bring the load lock chamber 13 to a predetermined vacuum degree, and an electric motor portion for driving the pump mechanism portion 21 ( 22). The electric motor part 22 consists of a brushless motor of the synchronous motor type, specifically, a brushless DC motor, and is driven by the electric current supply from the inverter 30 which comprises a control apparatus. The electric motor unit 22 is adapted to adjust the driving frequency (rotational speed command value) at the supply current from the interlock 30, so that the rotational speed is adjusted.

On the other hand, in the present embodiment, the electric motor unit 22 is driven by the inverter 30 at a constant voltage, and at the same time, the current value (supply current value) of the supply current to the electric motor unit 22 is determined by the electric motor unit ( The magnitude of the output torque of 22, i.e., the load torque of the vacuum pump 20 is correlated.

The inverter 30 has an ECU 31 and a current detector 32 which are electronic control units similar to a computer. The ECU 31 and the current detector 32 constitute motor control means. The current detector 32 detects a current value of the supply current for the electric motor unit 22 and provides this detection information to the ECU 31. The current detector 32 constitutes detection means for detecting a current value of a supply current for the electric motor unit 22. The ECU 31 adjusts the drive frequency at the supply current to the electric motor unit 22 based on the detection information provided from the current detector 32.

The ECU 31 calculates the output torque of the electric motor unit 22, that is, the load torque of the vacuum pump 20 based on the detection information (the supply current value for the electric motor unit 22) from the current detector 32. Calculate. In addition, the ECU 31 calculates the load torque increase amount per unit time of the vacuum pump 20 (hereinafter, for convenience, referred to as an increase speed of the load torque of the vacuum pump 20). The ECU 31 repeatedly monitors the increase rate of the load torque of the vacuum pump 20 every predetermined time.

And when ECU 31 determines that the increase speed of the load torque of the vacuum pump 20 is larger than a predetermined value, it determines with the rapid rise fluctuation which occurred in the increase speed of the load torque of the vacuum pump 20. As shown in FIG. By this determination, the ECU 31 sets the drive frequency at the supply current to the electric motor unit 22 for reducing the increase speed of the load torque of the vacuum pump 20 at the low speed side (rotation of the electric motor unit 22). Low speed side), that is, decrease (deceleration control).

The ECU 31 continues to monitor the increase rate of the load torque of the vacuum pump 20 even after determining that the increase rate of the load torque of the vacuum pump 20 has sharply increased and changed. Specifically, the ECU 31 of the present embodiment continuously executes the above-described monitoring as long as the ECU 31 is in the operating state. And when the ECU 31 judges that the increase rate of the load torque of the vacuum pump 20 rises and fluctuates rapidly by the above-mentioned monitoring, it carries out the said deceleration control, and the said drive frequency reduced by this control is carried out. Is maintained until the timing for judging whether the increase speed is greater than a predetermined value.

In addition, when the ECU 31 determines that the increase rate of the load torque of the vacuum pump 20 is rapidly rising and changed, a process of prioritizing the deceleration control to the deceleration control (for example, the electric motor unit 22 described later). It is repeatedly executed unless the supply current value for the control process is performed so as not to exceed the upper limit value (i2).

Next, the operation of the vacuum pump 20 configured as described above will be described with reference to the time charts of FIGS. 2A and 2B. The diagram 51 in FIG. 2A shows the drive frequency at the supply current to the electric motor section 22. In addition, the line 52 in FIG. 2B has shown the supply current value to the electric motor part 22. As shown in FIG.

The wafer transfer operation between the process chamber 12 and the load lock chamber 13 is performed by the vacuum pump 20 while the load lock chamber 13 is at the same predetermined vacuum level as the process chamber 12. The gate valve 14 is implemented in the open state. At this time, the gate valve 15 and the shut-off valve 19 are in the closed state.

In addition, the exchange operation of the wafer between the load lock chamber 13 and the external space of the semiconductor manufacturing apparatus 11 is performed by opening / closing the valve 19 with the gate valves 14 and 15 closed, The gate valve 15 is opened with the load lock chamber 13 at the same pressure (atmospheric pressure) as the external space. At this time, the shut-off valve 17 is closed.

Then, for example, when the load lock chamber 13 is brought to a predetermined degree of vacuum by the vacuum pump 20 after the wafer is loaded into the load lock chamber 13, the vacuum pump 20, that is, the electric motor unit 22 is driven. In the closed state, the opening / closing valve 17 is opened to start exhausting the load lock chamber 13. The time point t1 in FIG. 2A and FIG. 2B shows the time point of opening / closing valve 17, and until this time, ECU 31 rotates the electric motor part 22 at the high speed side (rotation of the electric motor part 22). It drives at the drive frequency fmax of the high speed side in speed.

On the other hand, since the opening / closing valve 17 was in the closed state before the time point t1, the pressure load (pressure load related to exhaust) of the vacuum pump 20 was almost zero, and the supply current to the electric motor portion 22 was minimal. The current value i1 is changing.

When the open / close valve 17 is opened at the time point t1, the gas in the load lock chamber 13 in the atmospheric pressure is rapidly introduced into the pump mechanism portion 21, so that the pressure load of the vacuum pump 20 increases rapidly. Thereby, the output torque of the electric motor part 22, ie, the load torque of the vacuum pump 20, shows a tendency to rise. That is, in FIG. 2B, the current value shows an upward trend from the time point t1. At this time, the increase rate of the current value, that is, the increase rate of the load torque of the vacuum pump 20 is zero from zero (since the current value i1 was changed before the time point t1, the increase rate of the current value is zero). Rather fluctuate at an increasing rate.

The ECU 31 calculates an increase rate of the load torque of the vacuum pump 20 based on the detection information from the current detector 32, and determines that the increase rate is greater than a predetermined value, and loads the vacuum pump 20. It is determined that a sudden rise change occurs in the increase speed of the torque. By this judgment, the ECU 31 determines the speed of the electric motor unit 22 to reduce the increase speed of the load torque toward a predetermined target value (for example, the increase speed of the load torque corresponding to the straight line 61 shown in Fig. 2B). A deceleration control is performed to reduce the rotation speed.

At this time, the ECU 31 gradually reduces the drive frequency at the supply current to the electric motor unit 22 by repeatedly executing the deceleration control. By this gradual deceleration process, the rotational speed of the electric motor part 22 gradually falls. That is, the drive frequency is gradually reduced from the drive frequency fmax by the ECU 31 starting at the time point t1.

By the reduction of this drive frequency, the rotational speed of the electric motor part 22 falls. And the fall tendency of the pressure load of the vacuum pump 20 is suppressed by this fall of the rotational speed, and the increase rate of the load torque of the vacuum pump 20 is reduced by this.

In addition, the ECU 31 adjusts the driving frequency so that the current value of the supply current to the electric motor unit 22 does not exceed the upper limit value i2. This adjustment process is performed in preference to the deceleration control. In other words, when the ECU 31 determines that the current value has reached the predetermined upper limit value i2, the driving frequency of the electric motor unit 22 is set at a low speed from the driving frequency f1 at the time point (in this embodiment, time t3). It drastically decreases toward the drive frequency fmin on the side.

By the fall of the rotational speed of the electric motor part 22 based on the sudden fall of this drive frequency, the output torque of the electric motor part 22, ie, the load torque of the vacuum pump 20, the tendency to increase is suppressed, and the upper limit ( It is restricted so as not to exceed the upper limit torque corresponding to i2). And ECU 31 maintains the rotational speed of the electric motor part 22 as high speed as possible in order to implement | achieve exhaust gas of the load lock chamber 13 which is high efficiency in the range which electric current value does not exceed upper limit value i2. To increase or decrease the drive frequency.

On the other hand, the upper limit i2 described above is to avoid the damage of the constituent members of the vacuum pump 20 due to the excessive output torque of the electric motor 22, that is, the load torque of the vacuum pump 20, and the like. It is set for that.

When the pressure load of the vacuum pump 20 decreases as the load lock chamber 13 is decompressed by the vacuum pump 20, the ECU 31 causes the electric motor unit to be in a range in which the current value does not exceed the upper limit value i2. In order to make the rotational speed of 22 as high as possible, the drive frequency is increased toward the drive frequency fmax (between time t4 and time t5). At this time, in this embodiment, as the pressure load of the vacuum pump 20 decreases despite the increase in the driving frequency, the load torque (that is, the current value) of the vacuum pump 20 shows a tendency to decrease. have.

In the present embodiment, the following effects can be obtained.

(1) The ECU 31 performs deceleration control to decrease the rotational speed of the electric motor unit 22 when the increase speed of the load torque of the vacuum pump 20 suddenly rises and changes. According to this, the increase rate at the time of raising the load torque of the vacuum pump 20 can be reduced. Therefore, the rapid rise fluctuation of the increase rate of the load torque of the vacuum pump 20 or the state in which the increase rate is large after this rise change are continued, thereby making it possible to reduce the impact the structural member of the vacuum pump 20 receives. Therefore, for example, in order to improve impact resistance, it is not necessary to reinforce the constituent members of the vacuum pump 20, and the enlargement and weight of the vacuum pump 20 due to this reinforcement are prevented.

(2) The ECU 31 calculates the load torque of the vacuum pump 20 based on the supply current value to the electric motor unit 22. According to this, in order to detect the load torque of the vacuum pump 20, it is not necessary to specifically form a torque sensor. Therefore, it can contribute to cost reduction or simplification of structure.

(3) The ECU 31 repeatedly monitors the increase rate of the load torque of the vacuum pump 20 every predetermined time, and determines that the increase rate of the increase rate of the load torque of the vacuum pump 20 is suddenly increased and changed. Continue afterwards. According to this, even after the said deceleration control is started, the rotational speed of the electric motor part 22 can be suitably controlled according to the fluctuation | variation of the increase speed of the load torque of the vacuum pump 20. FIG.

(4) The ECU 31 judges that the increase speed of the load torque of the vacuum pump 20 has suddenly risen and changed when the increase speed of the load torque of the vacuum pump 20 is larger than a predetermined value, and performs the deceleration control. do. According to this, for example, deceleration control is performed based on the difference (increase speed difference) between the increase speed of the load torque of the vacuum pump 20 at a predetermined time point and the increase speed at a predetermined time point separate from the predetermined time point. Compared with the aspect to be implemented, it becomes possible to omit the process for calculating the increase rate difference mentioned above. In other words, it becomes possible to reduce the processing burden on the ECU 31.

In the time chart of FIG. 2B, the pressure load (pressure load related to exhaust) of the vacuum pump 20 is almost constant in the value of the increase speed of the load torque before the start time t1 of the load torque rise of the vacuum pump 20. Since it is (almost zero), it is a constant value (zero). In such a case, for example, the value of the increase speed of the load torque of the vacuum pump 20 before the time point t1 is previously specified by a constant value such as zero, so as to determine whether the increase speed of the load torque is larger than the predetermined value. It is possible to accurately determine whether or not the increase speed of the load torque has sharply increased and changed. Therefore, in this case, it is possible to accurately determine whether or not the increase rate of the load torque of the vacuum pump 20 suddenly rises and changes without calculating the increase rate difference described above.

(5) The ECU 31 executes the deceleration control to reduce the increase speed of the load torque of the vacuum pump 20 toward a predetermined target value. According to this, the increase rate of the load torque of the vacuum pump 20 is controlled to approach or coincide toward the predetermined target value. By this control, the increase rate at the time of the increase of the load torque of the vacuum pump 20 is reduced rather than the conventional increase rate.

(6) The ECU 31 controls the electric motor unit 22 so that the load torque of the vacuum pump 20 does not exceed a predetermined upper limit value (the upper limit value of the load torque corresponding to the upper limit value i2 of the supply current). do. According to this, since the maximum value of the load torque which acts on the vacuum pump 20 by the ECU 31 is restrict | limited, deformation, damage, etc. of the structural member of the vacuum pump 20 by excessive load torque can be avoided. have.

(7) The deceleration control by the ECU 31 is performed by changing the drive frequency at the supply current to the electric motor portion 22 to the low speed side at the rotational speed of the electric motor portion 22. According to this, as the drive frequency is changed to the low speed side, the rotational speed of the electric motor unit 22 is lowered, and thus the pressure load of the vacuum pump 20 is lowered. The reduction in the increase rate of the load torque of the vacuum pump 20 can be realized by this drop in the pressure load.

(8) The electric motor part 22 was comprised with the brushless DC motor of the synchronous motor type. According to this, it becomes easy to make the electric motor part 22 highly durable compared with the motor with a brush. In addition, regardless of the magnitude of the load torque acting on the vacuum pump 20, the rotational speed of the electric motor unit 22 can be adjusted by adjusting the drive frequency of the supply current.

(9) Since the load lock chamber 13 is a chamber serving as a relay point when the workpiece is exchanged between the atmospheric pressure space surrounding the semiconductor manufacturing apparatus 11 and the process chamber 12, the load lock chamber 13 is a predetermined chamber. Increasing the pressure to atmospheric pressure at the degree of vacuum tends to be frequently performed. That is, in the vacuum pump 20 which exhausts the load lock chamber 13, the increase of the load torque accompanying the increase of the pressure load can generate | occur | produce frequently. Therefore, in this aspect, it is particularly effective to employ the inverter 30 having the motor control means of the present embodiment to improve the durability of the vacuum pump 20.

In addition, it can implement also in the following aspects, for example in the range which does not deviate from the meaning of this invention.

-In the above embodiment, when the ECU 31 determines that the increase speed of the load torque of the vacuum pump 20 is larger than the predetermined value, it is determined that the increase speed of the load torque of the vacuum pump 20 has suddenly increased and changed. And deceleration control for reducing the rotational speed of the electric motor unit 22. Instead of this, the ECU 31 calculates the rate of change of the load torque of the vacuum pump 20, that is, the amount of change of the increase rate per unit time, and judges that this calculation result is larger than the predetermined value. It may be configured to perform the deceleration control. According to this, even if the increase speed before the time point t1 of the load torque of the vacuum pump 20 is not constant, how much change has been made during the predetermined time with respect to the increase speed of the load torque of the vacuum pump 20. Can be accurately identified.

In this case, the ECU 31 calculates, for example, the difference between the increase speed of the load torque at the present time and the increase speed of the load torque at the time before the current time by a predetermined time. When the ECU 31 determines that the calculation result (increase speed difference) subtracting the increase speed of the load torque at the previous time point by a predetermined time from the increase speed of the load torque at the present time is larger than the predetermined value, the vacuum pump 20 It is determined that a sudden rise change in the increase speed of the load torque occurs. By this determination, the ECU 31 performs the deceleration control in order to reduce the increase rate of the load torque of the vacuum pump 20.

-The increase speed of the load torque of the vacuum pump 20 is from the time when the reduction of the drive frequency by the ECU 31 starts (time t1) to the time when the electric current value of the electric motor part 22 reaches the upper limit i2. It does not have to be a linear trend of growth in total. For example, if the increase speed of the load torque from the time point t1 is reduced from the conventional increase speed, then the increase speed of the load torque will be faster than the conventional increase speed until the current value reaches the upper limit value i2 after that. It may be possible. According to this, for example, the time until the current value reaches the upper limit value i2 can be made shorter than before while reducing the increase rate immediately after the start of the load torque rise of the vacuum pump 20.

The ECU 31 may be configured to carry out the deceleration control to reduce the rate of change of the increase rate of the load torque of the vacuum pump 20 (amount of change of the increase rate per unit time) toward a predetermined target value. In this case, for example, the rate of change of the increase speed of the load torque corresponding to the curve 62 shown in FIG. 3B is defined as the predetermined target value. 3A is a time chart which shows the drive frequency of the electric motor part 22 in this case, and FIG. 3B is a time chart which shows the electric current value in the electric motor part 22. As shown in FIG. In addition, the line 91 in FIG. 3A shows the drive frequency of the conventional electric motor similarly to FIG. 2A, and the line 92 in FIG. 3B has shown the current value of the conventional electric motor similarly to FIG. 2B.

According to this, the rate of change of the increase rate of the load torque of the vacuum pump 20 is controlled to approach or coincide toward the predetermined target value. By this control, the increase rate of the start time of the increase of the load torque of the vacuum pump 20 at least decreases compared with the conventional increase rate. Therefore, it becomes possible to reduce the impact resulting from the change rate of the increase rate of the load torque of the vacuum pump 20 among the impacts which the structural member of the vacuum pump 20 receives.

-After the ECU 31 determines that the increase rate of the load torque of the vacuum pump 20 by the ECU 31 is rapidly increased and changed (may be immediately after this determination, and the end of this determination At a point in time, which may be after a predetermined time has elapsed). According to this, for example, as compared with the case where the monitoring is repeatedly executed as long as the ECU 31 is in the operating state, it is possible to reduce the processing burden of the ECU 31 related to the monitoring.

In this case, the ECU 31 may limit the number of repetitions of the deceleration control (the number of times the deceleration control is repeatedly executed). According to this, while the impact which the structural member of the vacuum pump 20 receives at the time of the increase of the load torque of the vacuum pump 20 is made small, for example, the rotational speed of the electric motor part 22 is good, and the exhaust efficiency of the vacuum pump 20 is good. It becomes possible to return quickly by high rotation speed.

For example, if the lower limit is set to the drive frequency of the electric motor unit 22 and the electric motor unit 22 is driven so as not to fall below this lower limit, the number of repetitions of the deceleration control may not necessarily be limited. .

At the time of the reduction of the drive frequency of the electric motor part 22, it is possible to make a sudden decrease from the drive frequency fmax toward the drive frequency fmin without gradually decreasing the drive frequency. Also in this case, it is possible to reduce the increase rate at the time of raising the load torque of the vacuum pump 20.

The upper limit value i2 of the supply current for the electric motor unit 22 may not be set. That is, the limitation of the maximum value of the load torque in the vacuum pump 20 may not be implemented.

For example, a torque sensor for detecting the load torque of the vacuum pump 20 may be formed, and the load torque may be grasped by a value other than the supply current value of the electric motor unit 22.

-The electric motor part 22 can also be comprised with the brushless motor of the synchronous motor type other than a brushless DC motor. Examples of this motor include a reluctance synchronous motor, a stepping motor, an inductor type synchronous motor, a permanent magnet synchronous motor, a hysteresis synchronous motor, and the like. Moreover, the electric motor part 22 can also be comprised by the brushless motor of an induction motor type. It is also possible to comprise a brushless motor other than the above. Moreover, it can also be comprised by the motor with a brush (for example, a DC motor, a universal motor, etc.).

The electric motor part 22 may be a type which can adjust the rotational speed of the electric motor part 22 by adjusting the voltage value in the supply current to the said electric motor part 22. FIG. In this case, the voltage value corresponds to the rotational speed command value.

In the above embodiment, the vacuum pump 20 is used for the load lock chamber 13, but may be used for the process chamber 12. In addition, it can be used other than the semiconductor manufacturing apparatus 11.

-Although the said embodiment was made into the control of the electric motor part 22 when the open / close valve 17 was opened from the state in which the load lock chamber 13 was at atmospheric pressure, it is not limited to this. For example, in order to reduce the increase rate of the load torque of the vacuum pump 20 at the start of the electric motor part 22, deceleration control of an electric motor part may be implemented. In addition, in the present invention, the increase speed of the load torque of the vacuum pump 20 is not limited only to the rise from the state of zero, but the increase rate of the load torque at the time of the fluctuation of the increase from the increase speed greater than zero to the larger increase speed. It is also included to perform the deceleration control of the electric motor unit 22 to reduce the pressure.

Next, the technical idea grasped | ascertained from the said embodiment is described below.

(1) Claim 1 or 2 which repeats monitoring of the load torque increase per unit time of the said vacuum pump every predetermined time, and stops after this monitoring judges that the load torque increase per unit time of a vacuum pump rises and changes abruptly. Control device of the vacuum pump described.

(2) The control apparatus of the vacuum pump as described in technical idea (1) in which the frequency | count of repetition of the said deceleration control is limited.

(3) A vacuum pump including a pump mechanism portion for exhausting the exhaust target space to a predetermined vacuum and an electric motor portion for driving the pump mechanism portion, wherein the load torque increase amount per unit time of the above-described ball pump is abruptly increased. The control method of the vacuum pump characterized by performing deceleration control which reduces the rotational speed of an electric motor part when it rises fluctuate | variably.

As described above in detail, according to the inventions of claims 1 to 10, the durability of the vacuum pump can be improved without causing an increase in size or weight due to the reinforcement of the vacuum pump.

Claims (10)

In the vacuum pump provided with the pump mechanism part which exhausts in order to make an exhaust object space into a predetermined vibration, and the electric motor part which drives the said pump mechanism part, And a deceleration control for reducing the rotational speed of the electric motor unit when the load torque increase amount per unit time of the vacuum pump rises and fluctuates rapidly. The control apparatus of the vacuum pump of Claim 1 which calculates the load torque of the said vacuum pump based on the supply current value to an electric motor part. The method according to claim 1 or 2, wherein the load torque increase amount per unit time of the vacuum pump is repeatedly monitored for a predetermined time, and the monitoring is performed even after determining that the load torque increase amount per unit time of the vacuum pump is suddenly increased and changed. The control apparatus of the vacuum pump performed continuously. The deceleration according to any one of claims 1 to 3, wherein when the load torque increase per unit time of the vacuum pump is larger than a predetermined value, it is determined that the load torque increase amount per unit time of the vacuum pump is suddenly increased and changed. The control apparatus of the vacuum pump which performs control. The method according to any one of claims 1 to 3, wherein when the change rate of the load torque increase amount per unit time of the vacuum pump is larger than a predetermined value, it is determined that the load torque increase amount per unit time of the vacuum pump is sharply increased and changed. The control apparatus of the vacuum pump which performs the said deceleration control. The control apparatus of the vacuum pump of Claim 4 or 5 which implements the said deceleration control in order to reduce the load torque increase amount per unit time of the said vacuum pump toward a predetermined target value. 6. The control apparatus of a vacuum pump according to claim 5, wherein said deceleration control is performed to reduce a rate of change of the load torque increase amount per unit time of said vacuum pump toward a predetermined target value. The control apparatus of the vacuum pump as described in any one of Claims 1-7 which controls the electric motor part so that the load torque of the said vacuum pump may not exceed predetermined upper limit. The control apparatus of the vacuum pump as described in any one of Claims 1-8 which comprised the said electric motor part with the brushless motor of a synchronous motor type or an induction motor type. The said vacuum pump is a control apparatus of the vacuum pump as described in any one of Claims 1-9 which uses the load lock chamber provided in the process chamber as an exhaust object space in a semiconductor manufacturing apparatus.