JP5990943B2 - Turbo molecular pump - Google Patents

Description

  The present invention relates to a turbo molecular pump used in a semiconductor manufacturing apparatus, an analysis apparatus or the like.

In a manufacturing process of a semiconductor device or a liquid crystal display panel, an insulating film, a metal film, a semiconductor film, or the like is formed or etched in a process chamber such as a CVD apparatus. A turbo molecular pump is used when exhausting the gas introduced into the process chamber to bring the inside of the process chamber to a predetermined high vacuum.
The reaction product generated in the process chamber is exhausted through a turbine exhaust part composed of rotor blades and stator blades and a thread groove exhaust part composed of rotor cylindrical parts and screw stators in a turbo molecular pump.

As the reaction product, chlorine-based or fluorine-sulfide-based gas is generally used. However, the lower the degree of vacuum, that is, the higher the pressure, the higher the sublimation temperature and the easier it is to deposit inside the turbo molecular pump. When the reaction product accumulates inside the turbo molecular pump, the rotor comes into contact with the stator blades and the screw stator, so that the turbo molecular pump is temperature controlled so as to maintain a predetermined temperature.
In the turbo molecular pump, the turbine exhaust side is at a high vacuum, and the vacuum is low near the thread groove exhaust and the exhaust port, so reaction products accumulate on the gas contact surfaces near the thread groove exhaust and the exhaust port. It becomes easy.

  Therefore, a turbo molecular pump is known in which a heater and a cooling water pipe are provided in a base in which a thread groove exhaust part is accommodated and an exhaust port is formed, and the temperature is controlled so that the base is equal to or higher than the sublimation temperature of the reaction product. (For example, refer to Patent Document 1).

JP 2007-278192 A

In the manufacture of semiconductor devices, liquid crystal display panels, and the like, a process for etching a metal having a sublimation temperature exceeding 100 ° C. such as aluminum or titanium is required.
In a turbo molecular pump used when exhausting a reaction product having a sublimation temperature exceeding 100 ° C., the turbo molecular pump is maintained at a temperature exceeding 100 ° C. in order to suppress deposition inside the turbo molecular pump. There is a need to. However, in the past, cooling water is used to cool the turbo molecular pump, so if the turbo molecular pump is maintained at a temperature exceeding 100 ° C, the cooling water will boil, ensuring safety. Is difficult.

A turbo molecular pump according to the present invention includes a rotor having rotor blades arranged in multiple stages and a rotor cylindrical portion, a stator blade disposed between the rotor blades of each stage, and a screw constituting a thread groove exhaust portion together with the rotor cylindrical portion. In a turbomolecular pump comprising a stator, wherein rotor blades and stator blades are accommodated in an upper case, and a thread groove exhaust portion is accommodated in a base, a cooling pipe provided in the base and circulating a coolant having a boiling point exceeding 100 ° C. And a control means for controlling the temperature of the coolant via the cooling pipe so that the temperature inside the turbo molecular pump is maintained at a temperature exceeding 100 ° C., and the boiling point of the coolant is a temperature exceeding the target maintaining temperature of the pump, characterized that you have provided a heat exchange device for raising and lowering the temperature of the cooling liquid.
The turbo molecular pump of the present invention comprises a rotor having rotor blades arranged in multiple stages and a rotor cylindrical part, a stator blade arranged between the rotor blades of each stage, and a thread groove exhaust part together with the rotor cylindrical part In a turbo molecular pump including a screw stator that is housed in an upper case and having a rotor blade and a stator blade housed in a base, a coolant having a boiling point exceeding 100 ° C. is circulated. A cooling pipe, a control means for controlling the temperature of the cooling liquid via the cooling pipe so that the temperature inside the turbo molecular pump is maintained at a temperature exceeding 100 ° C., a cooler and a heater. The cooling pipe has an extension part extending to the outside of the base, and the cooler and the heater are serially along the extension direction to the extension part of the cooling pipe. Characterized by being arranged To.
Further, the turbo molecular pump of the present invention constitutes a rotor having multi-stage rotor blades and a rotor cylindrical portion, a stator blade disposed between the rotor blades of each stage, and a thread groove exhaust portion together with the rotor cylindrical portion. In a turbo molecular pump including a screw stator that is housed in an upper case and having a rotor blade and a stator blade housed in a base, a coolant having a boiling point exceeding 100 ° C. is circulated. A cooling pipe, and a control means for controlling the temperature of the coolant via the cooling pipe so that the temperature inside the turbo molecular pump is maintained at a temperature exceeding 100 ° C. The temperature is increased by heating the coolant with a heater to increase the temperature of the coolant .

  According to the present invention, since the cooling liquid having a boiling point exceeding 100 ° C. is used as the cooling liquid for cooling the turbo molecular pump, boiling of the cooling liquid can be suppressed, and safety can be easily ensured.

Sectional drawing which shows one Embodiment of the turbo-molecular pump which concerns on this invention. FIG. 2 is a block diagram illustrating an embodiment of temperature control of the turbo molecular pump illustrated in FIG. 1. FIG. 3 is a process flow diagram illustrating one embodiment of a temperature control method for the turbo molecular pump illustrated in FIG. 2. FIG. 4 is a process flow diagram as a sub-process of the heat exchange device in FIG. 3.

Hereinafter, an embodiment of a turbo molecular pump according to the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view of a magnetic bearing type turbo molecular pump. The turbo molecular pump 1 includes a case member 11 including an upper case 12 and a base 13. The flange 18 provided at the lower end of the upper case 12 and the flange 19 provided at the upper end of the base 13 are fastened by a fastening member such as a bolt with a seal member 42 interposed therebetween. Thus, the upper case 12 and the base 13 are sealed from the outside.

A rotor shaft 5 is disposed on the central axis of the case member 11. A rotor 60 is coaxially attached to the rotor shaft 5. The rotor shaft 5 and the rotor 60 are firmly fixed by a fastening member 48 such as a bolt.
The rotor shaft 5 is supported in a non-contact manner by a radial magnetic bearing 31 (two locations) and a thrust magnetic bearing 32 (upper and lower pair). The flying position of the rotor shaft 5 is detected by radial displacement sensors 33a and 33b and an axial displacement sensor 33c. The rotor shaft 5 magnetically levitated by the magnetic bearings 31 and 32 is rotated at a high speed by a motor 35.

  A rotor disk 38 is attached to the lower side of the rotor shaft 5 via a mechanical bearing 34. A mechanical bearing 36 is provided on the upper side of the rotor shaft 5. The mechanical bearings 34 and 36 are emergency mechanical bearings, and the rotor shaft 5 is supported by the mechanical bearings 34 and 36 when the magnetic bearing is not operating.

The rotor 60 has a two-stage structure of an upper side and a lower side, and a plurality of stages of rotor blades 6 are provided on the upper side. A portion below the lowermost rotor blade 6 is a rotor cylindrical portion 9.
On the upper side of the rotor 60, the rotor blades 6 and the stator blades 7 are alternately stacked in the axial direction of the pump with the ring-shaped spacer 21 interposed therebetween. Spacers 21 and stator blades 7 are alternately stacked on the upper surface of the base 13, and the upper case 12 is fixed to the base 13 by covering the spacers 21 and the stator blades 7 with the upper case 12. By doing so, the stacked spacer 21 and stator blade 7 are sandwiched between the upper surface of the base 13 and the step portion 12 a provided on the inner wall of the upper case 12.

A ring-shaped screw stator 8 is fixed to the base 13 with bolts 41 on the outer peripheral side of the rotor cylindrical portion 9 of the rotor 60. The screw stator 8 is formed in a substantially cylindrical shape, has a spiral protrusion 8a on the inner surface side, and a thread groove 8b is formed between the spiral protrusions 8a. The screw groove 8b is a gap for transferring gas molecules from above to below.
The rotor cylindrical portion 9 may be provided with a spiral protrusion and a screw groove, and the inner peripheral surface of the screw stator 8 may be a flat surface.

  The base 13 is provided with an exhaust port 45, and a back pump is connected to the exhaust port 45. In this state, the rotor 60 is magnetically levitated and is driven to rotate at a high speed by the motor 35, whereby the gas molecules on the intake port 15 side are exhausted to the exhaust port 45 side.

  The turbo molecular pump 1 has a turbine exhaust part 2 in the internal space of the upper case 12 and a thread groove exhaust part 3 in the internal space of the base 13. The turbine exhaust part 2 is composed of a plurality of stages of rotor blades 6 and a plurality of stages of stator blades 7, and the thread groove exhaust part 3 is composed of a rotor cylindrical part 9 and a screw stator 8.

  A flange 17 formed at the upper end of the upper case 12 is fastened to a mounting part of an exhaust system of a vacuum chamber such as a semiconductor device manufacturing apparatus (not shown) by a fastening member (not shown). When the rotor 60 is rotationally driven by the motor 35, gas molecules in the vacuum chamber flow into the turbo molecular pump 1 from the intake port 15 provided in the upper part of the upper case 12. The gas molecules flowing in from the intake port 15 are blown off downstream in the turbine exhaust part 2. Although not shown, the rotor blades 6 and the stator blades 7 are oppositely inclined in the direction of the blades, and the inclination angle is changed from the front side, which is the high vacuum side, to the downstream side, which is the downstream side. Is formed to change at an angle that is difficult to reverse. The gas molecules are compressed in the turbine exhaust part 2 and transferred to the thread groove exhaust part 3 below in the figure.

  In the thread groove exhaust section 3, when the rotor cylindrical section 9 rotates at a high speed with respect to the screw stator 8, an exhaust function by a viscous flow is generated, and the gas transferred from the turbine exhaust section 2 to the thread groove exhaust section 3 is compressed. However, it is transferred to the exhaust port 45 and exhausted.

  A cooling pipe 51 for circulating a coolant for cooling the turbo molecular pump 1 is disposed on the flange 19 of the base 13. Although details will be described later, the cooling pipe 51 extends from the inside of the base 13 to the outside, and a cooling liquid having a boiling point exceeding 100 ° C. is injected into the cooling pipe 51. Although not meant to be limiting, examples of the coolant include ethylene glycol having a boiling point of 196 ° C.

A groove 16 is provided on the bottom side of the base 13, and a temperature sensor 52 for detecting the temperature of the base 13 is attached in the groove 16.
A heater such as a heater for raising the temperature of the turbo molecular pump 1 is not attached to the case member 11 of the turbo molecular pump 1 shown as an embodiment. In this embodiment, the turbo molecular pump 1 is configured to be heated and cooled via a coolant circulating in the cooling pipe 51. This is possible because the coolant having a boiling point exceeding 100 ° C. is used, and the temperature of the coolant is increased to a high temperature exceeding 100 ° C., but a specific method will be described later.

FIG. 2 is a block diagram showing an embodiment of temperature control of the turbo molecular pump shown in FIG.
As described above, the cooling pipe 51 provided on the base 13 of the turbo molecular pump 1 is extended to the outside of the base 13, and the pump 71 allows a coolant having a boiling point of, for example, ethylene glycol to exceed 100 ° C. The liquid is discharged from the tank 72 into the cooling pipe 51. The cooling pipe 51 extended from the base 13 is heated and cooled by the heat exchange device 80.

That is, the heat exchange device 80 includes a heater 81 and a cooler 83. For example, the heater 81 includes a heater 82 wound around the cooling pipe 51. The cooler 83 includes, for example, a heat radiating portion 84 provided with fins and a number of branch pipes, a motor 85, and a fan 86 rotated by the motor.
The coolant circulated through the cooling pipe 51 by the pump 71 is stored in the tank 72.
The turbo molecular pump 1 has a temperature sensor 52 that detects the temperature of the base 13 and a coolant temperature that is attached in close contact with a portion that extends from the base 13 of the cooling pipe 51 in order to detect the temperature of the coolant. A sensor 53 is provided.

The controller 10 controls the operation of each unit so as to maintain the turbo molecular pump 1 at a target temperature. Detection values from the temperature sensors 52 and 53 are input to the controller 10. The controller 10 stores a target temperature (target maintenance temperature) T of the turbo molecular pump 1 in advance. The controller 10 compares the target temperature T with the detection value t of the turbo molecular pump 1 sent from the temperature sensor 52, and controls the heater 81 and the cooler 83 of the heat exchange device 80 to be turned on / off.
Hereinafter, a method for controlling the temperature of the turbo molecular pump 1 by the controller 10 will be described.

3 is a process flow diagram showing an embodiment of the temperature control method of the turbo molecular pump shown in FIG. 2, and FIG. 4 is a process flow diagram as a sub-process of the heat exchanger in FIG. .
3 and 4 are executed by the controller 10 illustrated in FIG.

In FIG. 3, first, when the turbo molecular pump 1 is turned on, the temperature t inside the turbo molecular pump 1 at that time is detected in step S1. A temperature t 52 inside the turbo molecular pump 1 is sent to the controller 10 from a temperature sensor 52 attached to the groove 16 of the base 13.
Next, in step S2, the controller 10 calculates a temperature difference ΔT = (T−t) between the preset target temperature T and the internal temperature t of the turbo molecular pump 1 at that time.

Next, in step S <b> 3, the temperature of the coolant is controlled by the heat exchanger 80 by the controller 10.
That is, in step S3, the processing flow of the sub-process illustrated in FIG. 4 is started. First, in step S11, it is determined whether or not the temperature difference ΔT between the target temperature T inside the turbo molecular pump 1 and the temperature t inside the turbo molecular pump 1 at that time is positive, and if it is positive (Yes), step S12. If it is negative (No), the process proceeds to step S14.

In step S12, the cooler 83 is turned off. That is, the drive of the motor 85 is stopped and the rotation of the fan 86 is stopped. Then, in step S13, the heater 81 is turned on and the heater 82 is heated.
Through steps S12 and S13, the coolant circulating in the cooling pipe 51 is heated, and the temperature of the base 13 rises. For this reason, the temperature inside the turbo molecular pump 1 rises.

The target temperature T inside the turbo molecular pump 1 is set to a temperature exceeding 100 ° C., for example, 110 to 130 ° C. In this way, since the coolant having a high boiling point exceeding 100 ° C. is used, the inside of the turbo molecular pump 1 can be raised to the target temperature by the coolant without attaching a heater to the base 13 as in the prior art. It becomes possible.
In one embodiment of the present invention, the cooling liquid has a function of heating as well as cooling the internal temperature of the turbo molecular pump 1. In this sense, the cooling liquid can be said to be a temperature control liquid.
The coolant that circulates in the cooling pipe 51 only needs to have a boiling point exceeding 100 ° C. In particular, it is desirable that the coolant is higher than the target temperature T.

On the other hand, if the result in Step S12 is negative, the heater 82 of the heater 81 is turned off in Step S14, and then the process proceeds to Step S15. In step S15, the cooler 83 is turned on. That is, the motor 85 is driven and the fan 86 rotates.
Through steps S14 and S15, the coolant circulating in the cooling pipe 51 is cooled, and the temperature of the base 13 decreases. For this reason, the temperature inside the turbo molecular pump 1 falls.

When step S13 or step S15 ends, the sub-process processing ends, and the process proceeds to step S4 in FIG.
In step S4, it is determined whether or not the temperature difference ΔT between the target temperature T of the turbo molecular pump 1 and the internal temperature t of the turbo molecular pump 1 is smaller than a predetermined value α.
If the result is affirmative in step S4, the process proceeds to step S3, and the processes in steps S11 to S13 or steps S11, S14, and S15 in FIG. 4 are repeated.

If negative in step S4, the process proceeds to step S5, and it is determined whether or not the turbo molecular pump 1 is turned off.
If no in step S5, the process returns to step S1 and the above-described processing is repeated. And a process is complete | finished when it affirms by step S5.

  In the above processing, when the cooler 83 is turned off in step S12 and the heater 81 is turned on in step S13, the temperature of the coolant gradually increases. And the temperature inside the turbo-molecular pump 1 rises with the rise in the temperature of this cooling liquid. That is, the temperature inside the turbo molecular pump 1 rises slightly later than the temperature of the coolant. Therefore, after the detection value of the coolant temperature sensor 53 is taken into the controller 10, it may be determined whether the temperature inside the turbo molecular pump 1 is normal based on the temperature of the coolant temperature sensor 53. .

  Further, when the heater 81 is turned off in step S14 and the cooler 83 is turned on in step S15, the circulation of the coolant is started. Immediately after the start, the temperature of the base 13 of the turbo molecular pump 1 is once several tens of times. After that, it gradually rises to the target temperature. Therefore, the detection value of the temperature sensor 52 and the detection value of the coolant temperature sensor 53 are considerably different. For this reason, in such an on / off switching period of the heat exchange device 80, it is determined whether the heater 81 and the cooler 83 are on or off based on the detection value of the coolant temperature sensor 53. Also good.

As described above, in the embodiment of the present invention, a liquid having a boiling point exceeding 100 ° C. is used as the cooling liquid for cooling the turbo molecular pump 1. For this reason, even if the target temperature inside the turbo molecular pump 1 is set to a temperature exceeding 100 ° C., the coolant does not boil and sufficient safety can be ensured.
For this reason, it is very effective as the turbo-molecular pump 1 used when exhausting the reaction product whose sublimation temperature exceeds 100 degreeC.

  In the above-described embodiment, the temperature of the base 13 provided with the screw groove exhaust portion and the exhaust port where the degree of vacuum is low and the sublimation temperature of the reaction product is high is controlled. It is possible to effectively suppress the deposition of the reaction product on the contact surface.

  In the above embodiment, since the coolant also has a function of increasing the temperature inside the turbo molecular pump 1, it is not necessary to provide a heater such as a heater in the turbo molecular pump 1. The structure can be simplified and the cost can be reduced.

  In the above embodiment, the heater 82 is used as the heater 81. However, other heaters such as induction heating and dielectric heating may be used.

  In the above-described embodiment, the fan 86 is used as the cooler 83. However, the cooling pipe is disposed in the refrigerant tank, or the cooling pipe is cooled by circulating the refrigerant. Other coolers may be used.

  In addition, the present invention can be applied with various modifications within the scope of the gist of the invention. In essence, a coolant having a boiling point exceeding 100 ° C. is used as a cooling liquid for cooling the turbo molecular pump 1. What is necessary is just to carry out temperature control so that the temperature inside a pump may be maintained at the temperature exceeding 100 degreeC.

DESCRIPTION OF SYMBOLS 1 Turbo molecular pump 2 Turbine exhaust part 3 Thread groove exhaust part 12 Upper case 13 Base 51 Cooling pipe 52 Temperature sensor 80 Heat exchange apparatus 81 Heater 83 Cooler

Claims (4)

A rotor having rotor blades arranged in multiple stages and a rotor cylindrical portion; a stator blade disposed between the rotor blades of each stage; and a screw stator that forms a thread groove exhaust portion together with the rotor cylindrical portion, In the turbo molecular pump in which the rotor blade and the stator blade are accommodated in the upper case, and the thread groove exhaust portion is accommodated in the base,
A cooling pipe provided in the base, in which a coolant having a boiling point exceeding 100 ° C. circulates;
The temperature inside the turbo molecular pump is controlled by controlling the temperature of the coolant via the cooling pipe.
Control means for controlling to be maintained at a temperature exceeding 00 ° C. ,
The boiling point of the coolant is a temperature exceeding the target maintenance temperature inside the pump,
Turbomolecular pump characterized that you have provided a heat exchange device for raising and lowering the temperature of the cooling liquid. 2. The turbo molecular pump according to claim 1 , wherein the heat exchange device includes a cooler and a heater, and the temperature inside the pump is controlled to turn on and off the cooler and the heater by a control unit. The turbo molecular pump is maintained at the target maintenance temperature. A rotor having rotor blades arranged in multiple stages and a rotor cylindrical portion; a stator blade disposed between the rotor blades of each stage; and a screw stator that forms a thread groove exhaust portion together with the rotor cylindrical portion, In the turbo molecular pump in which the rotor blade and the stator blade are accommodated in the upper case, and the thread groove exhaust portion is accommodated in the base,
A cooling pipe provided in the base, in which a cooling liquid having a boiling point exceeding 100 ° C. circulates;
Control means for controlling the temperature of the coolant via the cooling pipe so that the temperature inside the turbo molecular pump is maintained at a temperature exceeding 100 ° C .;
A heat exchange device having a cooler and a heater,
The cooling pipe has an extending part that extends to the outside of the base, and the cooler and the heater are serially arranged in the extending part of the cooling pipe along the extending direction. A turbo-molecular pump characterized by A rotor having rotor blades arranged in multiple stages and a rotor cylindrical portion; a stator blade disposed between the rotor blades of each stage; and a screw stator that forms a thread groove exhaust portion together with the rotor cylindrical portion, In the turbo molecular pump in which the rotor blade and the stator blade are accommodated in the upper case, and the thread groove exhaust portion is accommodated in the base,
A cooling pipe provided in the base, in which a coolant having a boiling point exceeding 100 ° C. circulates;
Control means for controlling the temperature of the cooling liquid via the cooling pipe so as to maintain the temperature inside the turbo molecular pump at a temperature exceeding 100 ° C., and
The rise in temperature inside the turbo-molecular pump, a turbo molecular pump which is characterized in that by raising the temperature of the cooling liquid by heating the cooling liquid by applying heat sink.

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