JP4673011B2 - Temperature control device for turbo molecular pump - Google Patents

Description

  The present invention relates to a temperature control device for a turbo molecular pump used in a semiconductor device or the like.

  Turbomolecular pumps are used as exhaust devices for semiconductor manufacturing equipment. In a semiconductor manufacturing apparatus, various process gases are used according to the reaction process. For example, in a turbo molecular pump used in a CVD apparatus, an etching apparatus, or the like, reactive gas is exhausted. Therefore, process gas deposits and reaction products are likely to adhere to the turbo molecular pump. Since deposits of such precipitates and reaction products are reduced as the pump temperature is higher, the conventional turbo molecular pump is designed to suppress the deposits of deposits and reaction products by heating the pump body with a heater. Yes.

  On the other hand, an aluminum alloy is generally used for the rotating body of the turbo molecular pump, and if the temperature of the rotating body becomes too high, there is a problem that the pump life is reduced due to deterioration of the aluminum material. In addition, for the motor provided inside the pump, if the operating temperature rises too much, problems such as insulation deterioration occur.

  Therefore, in the conventional turbo molecular pump, a cooling means is provided in addition to the heater described above, and the heating by the heater and the cooling by the cooling means are controlled so that the pump temperature becomes a predetermined target temperature (for example, , See Patent Document 1). Although temperature detection is performed by a temperature sensor provided in the base portion of the pump or the like, the temperature of a rotating body arranged in a vacuum is likely to be higher than that of the base portion. Therefore, the target temperature is set in consideration of the temperature difference between the base portion and the rotating body.

JP 2002-70788 A

  By the way, when a gas load is applied to the turbo molecular pump, the motor load increases and the motor heat generation increases, and further heat generation due to frictional heat between the rotating body and the gas occurs. Therefore, when the gas load increases, the temperature of the pump rises, and since the rotating body is in a vacuum, it is difficult to dissipate heat, and the temperature further rises compared to the base portion.

  Therefore, if the target temperature is set high, the temperature of the base portion becomes high and product adhesion can be prevented. However, when the gas load increases, the temperature of the rotating body exceeds the upper limit temperature for preventing deterioration of the material. There is a fear. As a result, in order to use the pump safely, there is a problem that the gas flow rate on the apparatus side must be suppressed. On the contrary, if the target temperature is set low, the temperature of the rotating body is kept low even if the gas load increases, so that the gas flow rate on the apparatus side can be increased. As a result, the adhesion amount of the product increases and the overhaul period for removing the product is shortened. Further, in the case of the magnetic bearing system, since the rotating body is held in a non-contact manner in a vacuum, there is a problem that there is no means for directly acquiring the temperature at a low cost.

According to a first aspect of the present invention, there is provided a temperature control device for a turbo molecular pump, comprising: a heating means for heating the pump body of the turbo molecular pump; a cooling means for cooling the pump body; and a pump temperature by controlling the heating means and the cooling means. Control means for controlling to a predetermined target temperature, acquisition means for acquiring load amount information corresponding to the temperature of the rotating body of the turbo molecular pump, and rotating body of the turbo molecular pump based on the load amount information acquired by the acquiring means When the temperature of the rotating body of the turbomolecular pump is determined to be equal to or higher than the predetermined value , the target temperature is set with a predetermined lower limit as a limit. low, when the temperature of the rotating body of the turbo-molecular pump is determined to be smaller than the predetermined value by judging means, the target temperature to increase the target temperature upper limit value set in advance as a limit Characterized in that a further means.
According to a second aspect of the present invention, in the temperature control device for a turbo molecular pump according to the first aspect, the acquisition means acquires load amount information based on the drive current of the rotating body driving motor of the turbo molecular pump. .
According to a third aspect of the present invention, in the temperature control device for a turbo molecular pump according to the first or second aspect, when the state where the target temperature is equal to the predetermined lower limit value continues for a predetermined time, the heating of the pump is stopped and / or Alternatively, a protective means for stopping the operation is provided.
According to a fourth aspect of the present invention, in the temperature control device for the turbo molecular pump according to any one of the first to third aspects, an alarm is issued when a state where the target temperature is equal to the predetermined lower limit value continues for a predetermined time. Means are provided.

  According to the present invention, since the target temperature can be changed so as to be an optimum target temperature according to the load condition of the pump, the pump is brought to an appropriate temperature according to various gas load conditions of the turbo molecular pump. Will be able to maintain.

  Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings. FIG. 1 is a sectional view showing a pump body 1 of a turbo molecular pump to which a temperature control device according to the present invention is applied. A rotating body 4 that is rotationally driven by a motor 6 is provided inside a casing 20 provided in the pump body 1. An aluminum alloy is used as the material of the rotating body 4, and the rotor 4 has a plurality of stages of rotor blades 21 and screw groove portions 22. On the other hand, a plurality of stages of stator blades 23 are alternately disposed with respect to the plurality of stages of rotor blades 21 disposed in the axial direction, and the thread groove portion 22 is tubular with a slight gap in the radial direction. A member 24 is disposed. The rotor blades 21 and the stator blades 23 are composed of turbine blades.

  Each stator blade 23 is maintained at a predetermined interval by a spacer 25, and the upper end of the uppermost spacer 25 is in contact with a protruding portion provided inside the upper end of the casing 20. By fixing the casing 20 to the base 28, the stator blades 23 and the spacers 25 that are alternately stacked in the axial direction are sandwiched between the upper end portion of the casing 20 and the base 28. When the rotating body 4 is rotated at a high speed by the motor 6, exhaust action is generated by the rotor blades 21 and the stator blades 23, and by the thread groove portions 22 and the cylindrical member 24. As a result, the gas on the intake port side is exhausted as indicated by an arrow G1, and is exhausted outside the pump by an auxiliary pump (not shown) connected to the exhaust port 26.

  The exhaust action by the rotor blades 21 and the stator blades 23 is effective on the high vacuum side, and the exhaust action by the screw groove 22 and the cylindrical member 24 is effective on the low vacuum side. It occurs more significantly on the low vacuum side. In the case of the turbo molecular pump shown in FIG. 1, a heater 29 is provided on the base 28 of the pump body. When exhausting a gas that easily adheres to a reaction product, the heater 28 raises the pump temperature. Suppresses adhesion of reaction products. Reference numeral 30 denotes a cooling device using cooling water, which controls cooling by the cooling device 30 and heating by the heater 29 to control the pump temperature. A temperature sensor 31 detects the temperature of the base 28, and the temperature detected by the temperature sensor 31 is used as the pump temperature.

  The turbo molecular pump shown in FIG. 1 is a five-axis control type magnetic bearing turbo molecular pump. The rotating body 4 is supported in a non-contact manner by electromagnets 51 and 52 constituting a radial magnetic bearing and an electromagnet 53 constituting an axial magnetic bearing. The The floating position of the rotating body 4 is detected by radial displacement sensors 71 and 72 and an axial displacement sensor 73. 27 is an emergency mechanical bearing, and the rotating body 4 is supported by the mechanical bearing 27 when the magnetic bearing is not operating.

  FIG. 2 is a block diagram showing a schematic configuration of the control device of the present embodiment and the pump body 1 shown in FIG. The turbo molecular pump includes the pump body 1 shown in FIG. 1 and a power supply device 2 that drives and controls the pump body 1. The power supply device 2 is connected to the pump main body 1 via a cable 3, and the cable 3 is connected to the receptacle 33 of the pump main body 1 shown in FIG. In FIG. 2, regarding the pump body 1, the motor 6, the heater 29, the cooling device 30, and the temperature sensor 31 that are necessary for explanation are shown.

  FIG. 2 mainly shows a configuration necessary for pump temperature control. The pump main body 1 includes a motor 6, a heater 29, a cooling device 30, and a temperature sensor 31, and the power supply device 2 includes a motor control unit. 5, the temperature control part 7, the temperature setting part 8, the input part 9, and the display part 10 are provided. Although the power supply device 2 includes a configuration relating to magnetic bearing control, the illustration thereof is omitted.

  For example, the temperature initial value T0 is input to the input unit 9 by manual input by an operator, for example, and the input unit 9 holds the input temperature initial value T0. This initial temperature value T0 is read into the temperature setting unit 8 as necessary. In addition, load information applied to the pump is input from the motor control unit 5 to the temperature setting unit 8. The display unit 10 displays the pump status and the like.

  In the pump temperature control in the present embodiment, the target temperature Tt for temperature control is automatically changed according to the load amount information corresponding to the temperature of the rotating body. The target temperature Tt is set by the temperature setting unit 8. The temperature setting unit 8 outputs the target temperature Tt to the temperature control unit 7 based on the temperature initial value T0 and the load amount information. The temperature control unit 7 controls the heater 29 and the cooling device 30 based on the detected temperature of the temperature sensor 31 and the target temperature Tt from the temperature setting unit 8 so that the pump temperature becomes the target temperature Tt.

  By the way, when a gas load is applied to an unloaded pump, the electric power supplied to the motor 6 increases in order to keep the pump rotational speed constant. The motor heat generation increases due to the increase in electric power, but most of the temperature rise of the rotating body due to the gas load is caused by the increase in motor heat generation. The increment can be load amount information corresponding to the temperature rise of the rotating body. For this reason, in the present embodiment, the integrated value (time integrated value) Ih of the motor current for a predetermined time is used as the load amount information described above.

<Explanation of temperature control operation>
Next, an example of temperature control will be described using the flowchart of FIG. The flowchart of FIG. 3 shows the procedure of the temperature control process performed in the power supply device 2, and the process starts when the main switch of the power supply device 2 is turned on. When the main switch is turned on, a magnetic bearing drive control device (not shown) provided in the power supply device 2 is activated, and the rotating body 4 is brought into a magnetic levitation state. When the pump start switch is turned on, the rotational drive of the rotating body 4 by the motor 6 is started.

  In step S1, it is determined whether the pump start switch is turned on and the pump operation is started. Then, when the pump operation is started, the process proceeds from step S1 to step S2. In step S 2, the temperature setting unit 8 reads the temperature initial value T 0 from the input unit 9 and sets the temperature initial value T 0 as the target temperature Tt of the temperature control unit 7. In step S <b> 3, the temperature controller 7 starts pump heating by the heater 29 based on the target temperature Tt set in step S <b> 2 and the temperature detected by the temperature sensor 31.

  The turbo molecular pump according to the present embodiment is a pump for a film forming process or an etching process, and the pump body 1 is heated and used in order to prevent reaction products from adhering. The temperature initial value T0 input to the input unit 9 is the target temperature Tt in standard use, and the temperature rise to the target temperature Tt (= temperature initial value T0) is started by starting the pump operation. As the temperature initial value T0, for example, a temperature of about 60 to 70 ° C. can be considered.

  In step S4, the motor current is integrated in the motor control unit 5, and the integrated value Ih is output to the temperature setting unit 8 as temperature information. The integration in step S4 is performed for a predetermined time. In step S5, it is determined whether or not the integrated value Ih calculated in step S4 is equal to or greater than a predetermined value Ih0. Here, the specified value Ih0 is a reference value for determining whether or not the temperature of the rotating body is equal to or higher than the upper limit temperature for preventing deterioration. For example, since the motor current increases as the gas load amount increases, the integrated value Ih becomes greater than the specified value Ih0 above a certain gas load amount.

If it is determined in step S5 that “Ih ≧ Ih0”, the process proceeds to step S6. If it is determined that “Ih <Ih0”, the process proceeds to step S10. When the process proceeds to step S6, that is, when the gas load amount is larger than normal and the temperature of the rotating body 4 tends to increase, it is determined in step S6 whether the current target temperature Tt is larger than the lower limit value _TL. judge. As the lower limit _TL , room temperature equivalent (about 40 ° C.) is selected.

If it is determined in step S6 that “Tt> T _L ”, the process proceeds to step S7 where the temperature setting unit 8 reduces the target temperature Tt by a predetermined temperature ΔT. For example, the target temperature Tt is lowered by 1 (deg). The new target temperature Tt reduced by the predetermined temperature ΔT is input to the temperature control unit 7, and the temperature control unit 7 controls the pump temperature based on the new target temperature Tt. At this time, when the pump temperature detected by the temperature sensor 31 is higher than the new target temperature Tt, the cooling is performed so that the pump body 1 is cooled and the pump temperature is lowered.

On the other hand, if “Tt ≦ T _L ” is determined in step S6, the process proceeds to step S8 to determine whether or not the time during which the target temperature Tt is maintained in the state of Tt = _TL is equal to or longer than a predetermined time. . If it is determined in step S8 that the time is equal to or longer than the predetermined time, an alarm is generated in step S9, and the pump is stopped by the protection operation (step S12). As an alarm generation method, for example, an alarm is displayed on the display device 10 provided in the power supply device 2 or an alarm signal is output to the semiconductor device side.

The reason for generating the alarm in step S9 is that even if the temperature is reduced, the overload state where the temperature of the rotary body of the pump still does not decrease continues, so the state of the target temperature Tt = _TL is maintained. When a predetermined time elapses, an alarm is generated to inform the operator that the device is in an irregular usage state where the overload state continues.

  On the other hand, if the process proceeds from step S5 to step S10, that is, if the gas load is about normal or smaller than normal, whether or not the current target temperature Tt is lower than the initial temperature value T0 in step S10. Determine. If “Tt ≧ T0” is determined in step S10, the process returns to step S4. If “Tt <T0” is determined, the process proceeds to step S11, and the temperature setting unit 8 increases the target temperature Tt by a predetermined temperature ΔT. For example, the target temperature Tt is increased by 1 (deg). However, when the target temperature Tt after the temperature increase exceeds the initial temperature value T0, the target temperature Tt is increased to the initial temperature value T0.

  The new target temperature Tt increased by the predetermined temperature ΔT is input to the temperature control unit 7, and the temperature control unit 7 controls the pump temperature based on the new target temperature Tt. At this time, when the pump temperature detected by the temperature sensor 31 is lower than the new target temperature Tt, control is performed so that the pump body 1 is heated by the heater 29 and the pump temperature is raised. The processing shown in FIG. 3 is continuously performed while the pump is operating, and when a pump stop signal is issued, the series of processing is terminated.

  FIG. 4 shows (a) a change in gas load and (b) a corresponding change in target temperature Tt. In FIG. 4A, the vertical gas load is represented by the flow rate of the gas flowing into the pump. As described above, the integrated value Ih in step S5 is obtained by time integration of the current value, and corresponds to the time integration of the gas load. Here, the time Δt shown in FIG. 4A is a predetermined time when the integrated value Ih is calculated in step S4, and the area value (gas load amount) of the hatched portion corresponds to the reference value Ih0. Think of it as In the following description, the gas load amount is replaced with the integrated current value Ih so that the correspondence with the flowchart of FIG. 3 is easily understood.

  Assuming that the target temperature Tt has already reached the initial temperature value T0 at the time t0, the time after the time t1 will be described. Since the integrated value Ih (that is, the gas load amount) between the times t0 and t1 is smaller than the reference value Ih0, the process proceeds from step S5 to step S10. However, since Tt = T0 already, the target temperature Tt is not increased. . Since this target temperature setting is applied at time ΔT following time t1, the target temperature Tt is maintained at T0 at times t1 to t2. Since the integrated value Ih at times t1 to t2 is also “Ih <Ih0”, Tt = T0 is similarly maintained. That is, the target temperature Tt = T0 is maintained until time t3.

  Since the integrated value Ih at the times t2 to t3 is larger than the reference value Ih0, the target temperature Tt at the subsequent times t3 to t4 is decreased by ΔT. At times t3 to t4, the gas load is again larger than normal, but since it is a short time, the integrated value Ih becomes smaller than the reference value Ih0, and the target temperature Tt at times t4 to t5 is increased by ΔT. . As a result, the target temperature Tt is Tt = T0.

Since the integrated value Ih at each predetermined time Δt is larger than the reference value Ih0 from time t5 to time t9, the target temperature Tt is decreased by ΔT every time Δt from time t6. However, since Tt = _TL at time t8, the target temperature Tt is not decreased and maintained at the lower limit value _TL at time t9. In the example shown in FIG. 4, since the alarm is set to be generated when the state of Tt = _TL is maintained for s predetermined time 2Δt, that is, the holding time in step S8 in FIG. 3 is set to 2Δt. Since it is set, an alarm is issued at time t10. However, since the integrated value Ih from time t9 to time t10 is smaller than the reference value Ih0, the target temperature Tt increases by ΔT at time t10.

[Modification]
In the embodiment described above, the integrated value Ih of the motor current is used as the load amount information, but the stator temperature of the motor 6 is detected by the temperature sensor 34 as shown in the modified example of FIG. It may be used as quantity information. When detecting the temperature of the motor 6, a temperature sensor such as a thermistor may be provided in the stator of the motor 6.

  In the modification shown in FIG. 5, since the pump temperature is controlled based on the temperature of the motor 6 that is directly affected by the upper limit temperature, the motor current that is indirect information as in the above-described embodiment. Compared with the case where control is performed based on the integrated value Ih, temperature control can be performed more accurately, and the motor 6 can be more reliably prevented from exceeding those upper limit temperatures. Of course, product accumulation is likely to occur downstream of the gas flow G1, that is, close to the base 28, so that the base temperature is detected by the temperature sensor 31 and used for pump temperature control as in the case shown in FIG. is there.

As described above, in the temperature control device according to the present embodiment, the target temperature is changed so as to be the optimum target temperature according to the load condition of the pump, and therefore the following operational effects can be achieved. Can do.
(1) Since the pump temperature is always maintained at the maximum temperature according to the load, product adhesion is reduced, and the maintenance cycle of the pump can be extended. Therefore, the running cost can be reduced.
(2) In the conventional pump in which the target temperature is fixed, the target temperature is automatically changed even in a situation where the pump operation must be stopped due to the temperature rise of the rotating body 4 or the motor 6. The turbo molecular pump using the temperature control device of the present embodiment can continue the operation and can cope with various gas load situations.
(3) The excessive temperature rise of the rotating body 4 and the motor 6 can be prevented, and the lifetime reduction of the turbo molecular pump can be prevented.

  The present invention is not limited to the above embodiment as long as the characteristics of the present invention are not impaired.

  In the correspondence between the embodiment described above and the elements of the claims, the heater 29 is a heating unit, the cooling device 30 is a cooling unit, the temperature control unit 7 is a control unit, the motor control unit 5 and the temperature sensor 34. Is an acquisition unit, a temperature setting unit 8 is a determination unit and a target temperature changing unit, a temperature setting unit 8 and a display unit 10 are alarm units, and a temperature setting unit 8, the motor control unit 5 and the temperature control unit 7 are protection units. Constitute.

It is sectional drawing which shows the pump main body 1 of the turbo-molecular pump to which the temperature control apparatus by this invention is applied. It is a block diagram which shows schematic structure of the control apparatus of this Embodiment, and the pump main body 1 shown in FIG. 4 is a flowchart illustrating a procedure of temperature control processing performed in the power supply device 2. (A) is a figure which shows the change of gas load, (b) is a figure which shows the change of the target temperature Tt corresponding to a gas load, respectively. It is a block diagram which shows a modification.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pump main body 2 Power supply device 4 Rotating body 5 Motor 6 Temperature setting part 7 Temperature control part 8 Motor control part 9 Input part 10 Display part 28 Base 29 Heater 30 Cooling device 31, 34 Temperature sensor

Claims (4)

Heating means for heating the pump body of the turbo molecular pump;
Cooling means for cooling the pump body;
Control means for controlling the heating means and the cooling means to control the pump temperature to a predetermined target temperature;
Acquisition means for acquiring load information corresponding to the temperature of the rotating body of the turbo molecular pump;
Determination means for determining whether the temperature of the rotating body of the turbo molecular pump is equal to or higher than a predetermined value based on the load amount information acquired by the acquisition means;
When the temperature of the rotating body of the turbo molecular pump is determined to be equal to or higher than a predetermined value by the determining means, the target temperature is lowered with a predetermined lower limit as a limit, and the rotating body of the turbo molecular pump is determined by the determining means. A turbo molecular pump temperature control device comprising: target temperature changing means for increasing the target temperature when a predetermined temperature is determined to be lower than the predetermined value. In the temperature control apparatus of the turbo-molecular pump according to claim 1,
The temperature control device for a turbo molecular pump, wherein the acquisition means acquires the load information based on a driving current of a rotating body driving motor of the turbo molecular pump. In the temperature control apparatus of the turbo-molecular pump according to claim 1 or 2,
A turbo molecular pump temperature control device, characterized in that a protection means is provided for stopping heating of the pump and / or stopping operation when a state where the target temperature is equal to a predetermined lower limit value continues for a predetermined time. . In the temperature control apparatus of the turbo molecular pump in any one of Claims 1-3,
A turbo molecular pump temperature control apparatus comprising: an alarm means for issuing an alarm when a state where the target temperature is equal to a predetermined lower limit value is continued for a predetermined time.

Images