TW201643322A - Turbo-molecular pump - Google Patents

Abstract

The present invention provides a turbo-molecular pump capable of reducing the maintenance cost. The turbo-molecular pump (1) includes a turbine wing pump unit (TP) comprising a fixing wing (21) and a rotating wing (12); a dragging pump unit (DP) arranged closer to an exhaust downstream side than the turbine wing pump unit (TP); and protective members (40, 41, 42) detachably disposed in a manner of covering an air contact surface that is arranged closer to an exhaust downstream side than the turbine wing pump unit (TP), so as to prevent attachment of accumulation to the air contact surface.

Description

Turbomolecular pump

The present invention relates to a turbo molecular pump for use in a pressure range from a vacuum to an ultra-high vacuum in a semiconductor manufacturing apparatus or an analysis apparatus or the like.

In the past, in processes such as dry etching or chemical vapor deposition (CVD) in semiconductor manufacturing engineering or liquid crystal panel manufacturing engineering, in the process of processing in a high vacuum process chamber. A vacuum pump such as a turbo molecular pump is used as a mechanism for forming a high vacuum. In such a process, a large amount of gas is supplied for processing in order to perform the process at a high speed.

In the case of processing such as etching or CVD, a reaction product is likely to be generated in the pump. Therefore, the reaction product is likely to accumulate in the contact gas portion in the turbomolecular pump. The reaction product deposited inside the turbomolecular pump is cleaned to remove deposits during regular maintenance. At the time of maintenance, the turbo molecular pump is decomposed, and the reaction product deposited in each part is removed by washing. Therefore, in the turbomolecular pump described in Patent Document 1 or Patent Document 2, it is proposed that only the components which are likely to accumulate the reaction product are decomposed and can be cleaned without disassembling the entire pump. [Progress Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Laid-Open Patent Publication No. 2003-278691 [Patent Document 2] Japanese Patent Laid-Open No. Hei-4-301197

[Problems to be solved by the invention]

However, when the reaction product is firmly adhered to the contact gas portion of the component, it is necessary to remove it by wiping or the like with a brush or the like. In other words, the vacuum pump used in the above-described treatment is generally subjected to corrosion-resistant treatment such as nickel plating in order to prevent corrosion or the like. Therefore, when the reaction product is rubbed off, there is a problem that even the plating layer is peeled off together with the reaction product. Therefore, in the case where the reaction product which has not fallen off in the usual cleaning treatment is deposited or even when the plating layer is removed, the component is generally required to be replaced. Therefore, there is a problem that the maintenance cost rises. [Technical solution to solve the problem]

A turbomolecular pump according to a preferred embodiment of the present invention includes: a turbine wing pump portion including a fixed wing and a rotary wing; a traction pump portion disposed on a downstream side of the exhaust gas than the turbine wing pump portion; and a protective member to cover The turbine wing pump portion is detachably provided to be in contact with the contact gas surface on the downstream side of the exhaust gas to prevent adhesion of the deposit to the contact gas surface. In a further preferred embodiment, the traction pump unit includes a cylindrical rotor and a stator disposed with a predetermined gap with respect to the cylindrical rotor, the protective member covering the between the turbine wing pump portion and the stator Provided in contact with at least a portion of the gas surface of the stator that contacts the gas surface. In a more preferred embodiment, the protective member is in thermal contact with the stator. In a further preferred embodiment, the protective member is detachably fixed to a contact gas surface on the exhaust downstream side of the traction pump unit via a heat insulating material. In a more preferred embodiment, the surface of the protective member is formed with a black nickel plating layer containing a fluororesin. [Effects of the Invention]

According to the present invention, a reduction in maintenance cost of the turbo molecular pump can be achieved.

Hereinafter, embodiments for carrying out the invention will be described with reference to the drawings. Fig. 1 is a cross-sectional view showing an embodiment of a turbomolecular pump of the present invention. The turbomolecular pump 1 includes a rotor 10 that forms a multi-stage rotary wing 12 and a rotor cylindrical portion 13. A rotor shaft 11 is fixed to the rotor 10. The rotor shaft 11 is supported by a radial magnetic bearing 32 and an axial magnetic bearing 33, and is rotationally driven by a motor 34.

When the magnetic bearing 32 and the magnetic bearing 33 are not operated, the rotor shaft 11 is supported by the mechanical bearing 35a and the mechanical bearing 35b. The radial magnetic bearing 32, the axial magnetic bearing 33, the motor 34, and the mechanical bearing 35b are housed in the base 30 fixed to the casing 20.

On the inner side of the pump casing 23, a plurality of stages of fixed wings 21 are arranged in the pump shaft direction corresponding to the multi-stage rotary blades 12. A plurality of turbine blades arranged in the circumferential direction are provided in each of the rotor blades 12 and the fixed blades 21 . The multistage fixed wings 21 are laminated via the annular spacers 29, respectively. The laminated body is disposed on the casing 20. In the turbomolecular pump 1, the multi-stage rotary vane 12 and the fixed vane 21 constitute a turbine wing pump portion TP.

The cylindrical stator 22 is disposed on the outer peripheral side of the rotor cylindrical portion 13 with a small gap therebetween. The stator 22 is fixed to the casing 20 by bolts 222. A thread groove is formed in either the outer circumferential surface of the rotor cylindrical portion 13 or the inner circumferential surface of the stator 22, and the rotor cylindrical portion 13 and the stator 22 constitute the traction pump portion DP. Further, in the example shown in FIG. 1, the traction pump unit DP constitutes a Holweck pump in which the stator 22 has a screw groove in the pump axis direction.

When the rotor 10 rotates at a high speed, the gas that has flowed in from the intake port 230 of the pump casing 23 is discharged by the turbine wing pump unit TP (the rotor blade 12 and the fixed blade 21), and the traction pump portion DP (the rotor cylinder portion 13 and the stator) is used. 22) Further compression. Further, finally, it is discharged from the exhaust pipe 26 provided in the casing 20. A rear pump (not shown) is connected to the exhaust pipe 26. Generally, an aluminum material is used for the rotor 10, the stator 22, the casing 20, and the like, and surface treatment such as nickel plating is performed to prevent corrosion.

In the case of exhausting a process using a gas in which a reaction product is easily deposited, a reaction product (for example, aluminum chloride or the like) tends to accumulate in the pump. The higher the pressure in the pump, the lower the temperature, the more easily these deposits accumulate, and the more the downstream side of the pump is, the easier it is to deposit deposits. In the case of the turbomolecular pump 1 shown in Fig. 1, since the turbine vane pump portion TP has a low pressure, the deposit of the deposit is relatively small. However, at the downstream side of the vicinity of the lowermost stage of the turbine wing pump portion TP, the pressure rises and the deposit tends to adhere.

Therefore, the heating heater 200 and the cooling liquid pipe 223 are provided in the casing 20, and the heater is turned on and off and the coolant is turned on and off to maintain the stator 22 at a desired temperature. Thereby, the accumulation of the reaction product to the stator 22 is prevented, and the performance of the traction pump unit due to the deposit or the contact of the stator 22 with the rotor cylindrical portion 13 or the like is prevented.

When the pump is operated, the temperature of the rotor rises due to heat generated by the gas discharge. The stator 22 also rises in temperature due to radiant heat from the rotor cylindrical portion 13. Therefore, the temperature of the stator 22 becomes higher than the case 20 or the substrate 30. As a result, the contact gas surface of the casing 20 or the substrate 30 having a lower temperature tends to accumulate the reaction product. In particular, the pressure is relatively increased on the downstream side of the traction pump unit DP, and thus the reaction product is likely to accumulate on the contact gas surfaces of the casing 20, the base 30, and the exhaust pipe 26.

In the present embodiment, a protective member 40 that protects against the deposition of the reaction product and can be easily and inexpensively replaced is disposed on the contact gas surface (wall surface) on which the deposit is likely to adhere to the downstream side of the turbine blade pump portion TP. Member 41, protective member 42.

Fig. 2 is an enlarged view of a portion on the downstream side of the turbine wing pump portion TP of Fig. 1 . Arrow G of Fig. 2 schematically shows the flow of gas. The gas discharged from the turbine wing pump portion TP is further discharged by the traction pump portion DP of the subsequent stage, and is discharged from the exhaust pipe 26. The screw groove 22a of the stator 22 is formed on a surface facing the rotor cylindrical portion 13, and its radial direction position is near the vicinity of the wing root portion of the lowermost rotary blade 12. Therefore, as shown in FIG. 2, the gas discharged from the turbine wing pump portion TP flows along the upper end surface of the stator 22 so as to wind up and flow into the screw groove 22a.

As a result, the residence time of the gas is prolonged in the space between the lowermost rotating blade 12 and the upper end of the stator 22. Therefore, deposits are likely to occur on the contact gas surface facing the retention space, that is, the upper end surface of the stator 22 or the inner circumferential surface of the casing 20. In the present embodiment, the protective member 40 is disposed so as to cover the reaction gas surface of the casing 20 and the contact gas surface of the stator 22 in the contact gas surface between the rotor blade 12 and the stator 22 to prevent reaction products. The accumulation of contact gas surfaces.

3(a) and 3(b) are views showing the shape of the protective member 40. 3(a) is a plan view of the protective member 40, and FIG. 3(b) is a cross-sectional view taken along line A1-A1 of the protective member 40. The protective member 40 includes a bottom plate portion 400 that covers the contact gas surface (upper end surface) of the stator 22, and a cylindrical side wall portion 401 that is erected on the outer peripheral side edge of the bottom plate portion 400. A plurality of through holes 402 are formed in the bottom plate portion 400, and the through holes 402 penetrate the bolts 222 (see FIG. 2) that fix the bottom plate portion 400 to the upper end surface of the stator 22. As shown in FIG. 2, when the protective member 40 is fixed to the stator 22 by the bolt 222, the side wall portion 401 is disposed close to the inner circumferential surface of the casing 20. Of course, the side wall portion 401 may also be in contact with the inner circumferential surface of the casing 20. The smaller the gap between the side wall portion 401 and the inner circumferential surface of the casing, the more the deposition of the reaction product on the inner circumferential surface of the casing can be suppressed.

When such a protective member 40 is provided, the reaction product is deposited on the bottom plate portion 400 and the side wall portion 401 of the protective member 40, and the formation of deposits on the inner circumferential surface of the casing and the upper end surface of the stator 22 can be reduced. In the reaction product removal operation during pump maintenance, even if the deposit adhering to the surface of the protective member 40 cannot be removed by washing, the protective member 40 itself may be replaced. As shown in Fig. 3 (a) and Fig. 3 (b), the protective member 40 is formed by processing a metal (aluminum alloy or stainless steel) sheet material, and is formed by reacting a product when the protective member 40 is not provided. The stator 22 or the housing 20 can be manufactured at a lower cost.

The advantages of providing the protective member 40 will be described. When the protective member 40 is not provided, the reaction product is deposited on the upper end surface of the stator 22 or the inner circumferential surface of the casing 20, that is, the contact gas surface of the stator 22 or the casing 20. In the case where the reaction product is hard to be removed by washing or the deposit is formed, the plating layer formed on the surface of the stator 22 or the casing 20 is peeled off, and the stator 22 or the casing 20 needs to be replaced. On the other hand, by providing the replaceable protective member 40 as in the present embodiment, it is possible to prevent the reaction product from accumulating on the contact gas surface of the stator 22 or the casing 20, and it is only necessary to clean the protective member 40 during maintenance. Replace it. As described above, the protective member 40 obtained by bending only the aluminum alloy or stainless steel sheet material is very inexpensive compared to the casing 20 or the stator 22. Therefore, the maintenance cost can be reduced.

In the protective member 40 shown in FIG. 3 (a) and FIG. 3 (b), the edge of the outer peripheral side of the bottom plate portion 400 is bent by press working or the like to form the side wall portion 401. However, when the height of the side wall portion 401 is relatively high, it is difficult to form the wall portion by press working or the like, and the processing cost also increases. In this case, as shown in FIGS. 4(a) and 4(b), the bottom plate portion 400 and the side wall portion 401 may be formed of different members. In this case, the bottom plate portion 400 is an annular plate material having the same shape as the bottom plate portion 400 shown in FIGS. 3( a ) and 3 ( b ).

4(a) and 4(b) are views showing an example of a method of forming the side wall portion 401. FIG. 4(a) is a view showing a band member 403 for forming the side wall portion 401. The lower side of the band member 403 is formed with four tabs 404. Each of the lugs 404 is formed with a through hole 404a for screwing the side wall portion 401 to the upper end surface of the stator 22. The belt-shaped member 403 is bent into a ring shape as shown in FIG. 4(b) to form the side wall portion 401, and the respective lugs 404 are bent toward the inner side of the annular side wall portion 401. Both end portions 403a and 403b of the annularly curved band member 403 are joined by welding or the like.

Further, in the example shown in FIG. 2, the protective member 40 is fixed to the upper end surface of the stator 22, but may be fixed to the casing 20 side. However, in the case where the temperature of the stator 22 and the casing 20 is compared, the temperature of the stator 22 that receives the radiant heat from the rotor 10 (the rotor cylindrical portion 13) is higher than that of the casing 20. Therefore, in order to keep the temperature of the protective member 40 higher, the protective member 40 is preferably fixed to the stator 22. The lower the temperature of the contact gas surface (wall surface), the more easily the reaction product accumulates. Therefore, by fixing the protective member 40 to the stator 22 having a higher temperature, it is possible to further suppress the deposition of the reaction product on the protective member 40.

Further, the pressure on the downstream side of the traction pump unit DP is further increased than the pressure on the intake side of the traction pump unit DP, so that the deposit of the deposit is further remarkable. In the turbomolecular pump 1 of the present embodiment, the protective member 41 and the protective member 42 are provided inside the casing 20 and the exhaust pipe 26 to which the stator 22 is fixed, on the downstream side of the traction pump unit DP.

5(a) and 5(b) are views showing the shape of the protective member 41, (a) is a plan view, and (b) is a cross-sectional view taken along line A2-A2. The protective member 41 includes a bottom plate portion 410 fixed to the bottom plate portion 410 of the casing 20, a side wall portion 411 that is erected on the inner circumferential side of the bottom plate portion 410, and a side wall portion 412 that is erected on the outer peripheral side edge of the bottom plate portion 410. The bottom plate portion 410 is formed with a plurality of through holes 410a for screwing. The side wall portion 411 on the inner circumferential side is an annular wall portion, and is disposed to face the outer circumferential surface of the cylindrical portion of the base 30.

A notch portion 412a is formed on the left side wall portion 412 on the left side of the drawing. As shown in FIG. 1, the side wall portion 412 is a wall portion that faces the inner circumferential surface of the casing 20. The notch portion 412a of the side wall portion 412 faces the exhaust port 20a (see FIG. 2) to which the exhaust pipe 26 is attached. The gas discharged to the exhaust side of the traction pump unit DP flows into the exhaust pipe 26 through the notch portion 412a of the protective member 41 (see FIG. 2). The gap between the side wall portion 411 and the side wall portion 412 of the protective member 41 and the wall surface covered by them (the outer circumferential surface of the base cylindrical portion and the inner circumferential surface of the casing 20) is set as small as possible. Thereby, it is possible to suppress the deposition of the reaction product on the wall surface covered by the side wall portion 411 and the side wall portion 412 as much as possible.

As in the case of the protective member 40, the higher the temperature of the protective member 41, the more the deposition of the reaction product can be suppressed. The protective member 41 faces the lower end faces of the rotor cylindrical portion 13 and the stator 22 which are higher than the casing 20 or the base 30. Therefore, in order to prevent heat incident from the rotor cylindrical portion 13 and the stator 22 to the protective member 41 due to radiation from being scattered to the base 30 to which the protective member 41 is fixed, the heat insulating material 43 is interposed in the protective member 41. Between the substrate 30 and the substrate 30. The temperature of the protective member 41 can be kept high as compared with a case where the protective member 41 is brought into contact with and fixed to the substrate 30. Thereby, accumulation of the reaction product with respect to the protective member 41 can be suppressed.

6(a) and 6(b) are views showing the shape of the protective member 42 disposed in the exhaust pipe 26. In FIGS. 6(a) and 6(b), (a) is a view of the protective member 42 viewed from the outlet side of the exhaust pipe 26, and (b) is a cross-sectional view of the protective member 42. The protective member 42 is a cylindrical body, and one end thereof is formed with a flange-like portion 421 that is bent outward. As shown in FIG. 2, the protective member 42 is attached to the casing 20 so as to be inserted into the exhaust pipe 26.

When the protective member 42 is to be attached to the exhaust pipe 26, first, before the exhaust pipe 26 is attached to the exhaust port 20a, the protective member 42 is taken out from the casing exhaust port side of the exhaust pipe 26 (Fig. 2 Insert on the right side). At this time, the protective member 42 is inserted until the flange-like portion 421 abuts against the end portion of the exhaust pipe 26. Next, the exhaust pipe 26 is screwed to the casing 20. As shown in FIG. 2, the flange-like portion 421 of the protective member 42 is disposed in a space between the right end of the exhaust pipe 26 and the cutout portion 412a of the protective member 41. Therefore, the movement of the protective member 42 in the left-right direction is restricted by the right end of the exhaust pipe 26 and the cutout portion 412a. Further, in the case where the protective member 42 is disposed in the exhaust pipe 26, in order to increase the conductance of the protective member 42 as much as possible, it is preferable to make the outer peripheral surface of the protective member 42 and the exhaust pipe 26 The inner peripheral surface is in close contact.

The inner peripheral surface of the exhaust gas pipe 26 that is in contact with the gas surface is almost covered by the protective member 42 except for the outlet region of the exhaust pipe 26. Therefore, it is possible to substantially prevent the deposition of the reaction product to the exhaust pipe 26. The protective member 42 is cleaned or replaced during maintenance. Further, when the other exhaust pipe is connected to the left end of the exhaust pipe 26, an O-ring having a center ring is provided. Therefore, in order to secure the arrangement area of the O-ring having the center ring, the protective member 42 does not extend to the left end of the exhaust pipe 26.

In the case of the protective member 41 and the protective member 42, as in the case of the protective member 40, only the plate material or the cylindrical material is subjected to bending processing, and thus it can be produced relatively inexpensively. Therefore, by providing the protective member 41 and the protective member 42, the cost associated with the removal of the reaction product during maintenance can be reduced. Further, in the case of the protective member 41, the side wall portion 411 and the side wall portion 412 can be formed of a band member separately provided as shown in Figs. 4(a) and 4(b).

In addition, the protective member 40 to the protective member 42 are formed of a plate material such as aluminum alloy or stainless steel, and a surface treatment of nickel plating (for example, electroless nickel plating) is performed in order to improve corrosion resistance. Further, in order to easily absorb the radiation from the rotor 10, black nickel plating having a high emissivity can be formed. Black nickel plating is a two-layer structure of a Ni-P layer and a black oxide film, and the emissivity is very high.

Further, instead of nickel plating or black nickel plating, nickel plating or black nickel plating containing a fluororesin may be used. Nickel plating containing a fluororesin is performed by uniformly dispersing fine particles of polytetrafluoroethylene (PTFE) in electroless nickel plating. Therefore, a low friction film which is substantially equivalent to the fluororesin coating can be obtained. As a result, it is easy to remove the reaction product deposited and deposited on the protective member 40 to the protective member 42.

As described above, the turbomolecular pump 1 of the present embodiment includes the turbine blade pump unit TP including the fixed blade 21 and the rotary blade 12, and the traction pump unit DP is disposed closer to the turbine blade pump unit TP. The exhaust gas downstream side; the protective member 40, the protective member 41, and the protective member 42 are detachably provided so as to cover the contact gas surface on the exhaust downstream side of the turbine wing pump portion TP, and prevent adhesion of the deposit to the contact gas surface. .

By providing the detachable protective member 40 to the protective member 42, it is possible to suppress the adhesion of the deposit to the contact gas surface where the deposit is likely to adhere. Further, even in the case where deposits are hard to be removed, it is only necessary to replace the protective member 40 to the protective member 42 during maintenance, so that maintenance cost can be reduced.

For example, when the traction pump unit DP is a Holvik type traction pump unit including the rotor cylindrical portion 13 and the stator 22, it is preferable to cover the upper end surface of the stator 22 having a large amount of deposition of deposits. The protective member 40 is provided. Further, by bringing the protective member 40 into thermal contact with the stator 22 having a relatively high temperature, the temperature of the protective member 40 can be kept high, and the adhesion of the deposit to the protective member 40 can be reduced, so that the maintenance period can be made longer.

Further, as shown in FIG. 2, the contact gas surface on the exhaust downstream side of the traction pump portion DP, that is, the wall surface of the base 30 or the wall surface of the casing 20 may be covered, and the protective member 41 can be insulated by the heat insulating material 43. It is fixed by loading and unloading. The protective member 41 is radiated from the rotor cylindrical portion 13 or the stator 22 having a high temperature, and the temperature rises. Therefore, by fixing the protective member 41 to the base 30 having a relatively low temperature via the heat insulating material 43, the temperature of the protective member 41 can be prevented from being lowered, and the adhesion of the deposit to the protective member 41 can be suppressed. In addition, a material having a lower thermal conductivity than the substrate 30 is used in the heat insulating material 43. For example, in the case where the substrate 30 is an aluminum alloy, it may be a stainless steel material.

Further, by forming a black nickel plating layer containing a fluororesin on the surfaces of the protective member 40 to the protective member 42, the following operational effects are achieved. By forming black nickel plating, it is easy to absorb radiation from the rotor 10 or the stator 22 as a high-temperature member, and the temperature of the protective member 40 to the protective member 42 can be kept higher. As a result, adhesion of the deposit to the protective member 40 to the protective member 42 can be suppressed. Further, by including the fluororesin in the black nickel plating, the deposit adhering to the protective member 40 to the protective member 42 can be easily removed, and the work cost of the deposit removing operation can be reduced.

Various embodiments and modifications have been described above, but the present invention is not limited to these contents. Other aspects that can be considered within the scope of the technical idea of the present invention are also included in the scope of the present invention. For example, in the turbomolecular pump 1 shown in FIG. 1, the casing 20 provided with the stator 22 is separated from the base 30 in which the motor stator or the magnetic bearing electromagnet or the like is housed, but the casing 20 and the base 30 may be used. One body. Further, the magnetic bearing type turbomolecular pump has been described as an example, but the same can be applied to a non-magnetic bearing type turbomolecular pump. Further, the traction pump unit DP is a Holvik pump type traction pump. However, the present invention is not limited thereto, and may be, for example, a Siegbahn pump type traction pump.

1‧‧‧ turbomolecular pump
10‧‧‧Rotor
11‧‧‧Rotor shaft
12‧‧‧Rotating Wings
13‧‧‧Rotor cylinder
20‧‧‧shell
20a‧‧‧Exhaust port
21‧‧‧Fixed Wing
22‧‧‧ Stator
22a‧‧ thread groove
23‧‧‧ pump casing
26‧‧‧Exhaust pipe
29‧‧‧Circular spacers
30‧‧‧Base
32‧‧‧radial magnetic bearings
33‧‧‧Axial magnetic bearings
34‧‧‧Motor
35a, 35b‧‧‧ mechanical bearings
40～42‧‧‧protective components
43‧‧‧Insulation materials
200‧‧‧heater
222‧‧‧ bolt
223‧‧‧Coolant tube
230‧‧‧ suction port
400‧‧‧Bottom plate
401‧‧‧ Sidewall
402, 404a, 410a‧‧‧through holes
403‧‧‧Band members
403a, 403b‧‧‧ end
404‧‧‧ 耳耳
410‧‧‧Bottom plate
411, 412‧‧‧ side wall
412a‧‧‧cutting section
421‧‧‧Flange
DP‧‧‧ traction pump
G‧‧‧The flow of gas
TP‧‧‧Turbo wing pump

Fig. 1 is a cross-sectional view showing an embodiment of a turbomolecular pump of the present invention. Fig. 2 is an enlarged view of a portion on the downstream side of the turbine wing pump portion. 3(a) and 3(b) are views showing the shape of the protective member 40. 4(a) and 4(b) are views showing an example of a method of forming the side wall portion 401. 5(a) and 5(b) are views showing the shape of the protective member 41. 6(a) and 6(b) are views showing the shape of the protective member 42.

12‧‧‧Rotating Wings

13‧‧‧Rotor cylinder

20‧‧‧shell

20a‧‧‧Exhaust port

21‧‧‧Fixed Wing

22‧‧‧ Stator

22a‧‧ thread groove

26‧‧‧Exhaust pipe

30‧‧‧Base

40~42‧‧‧protective components

43‧‧‧Insulation materials

421‧‧‧Flange

DP‧‧‧ traction pump

G‧‧‧The flow of gas

TP‧‧‧Turbo wing pump

Claims (5)

A turbo molecular pump, comprising: a turbine wing pump portion including a fixed wing and a rotary wing; a traction pump portion disposed on a downstream side of the exhaust gas than the turbine wing pump portion; and a protective member covering the ratio The turbine wing pump portion is detachably provided to be in contact with the gas surface on the downstream side of the exhaust gas, and prevents adhesion of the deposit to the contact gas surface. The turbomolecular pump of claim 1, wherein the traction pump portion includes a cylindrical rotor and a stator disposed with a predetermined gap with respect to the cylindrical rotor, the protective member covering the turbine wing A portion of the contact gas surface of the stator between the pump portion and the stator is disposed at least a portion of the contact gas surface of the stator. The turbomolecular pump of claim 2, wherein the protective member is in thermal contact with the stator. The turbomolecular pump according to claim 1, wherein the protective member is detachably fixed to a contact gas surface on a downstream side of the exhaust gas of the traction pump unit via a heat insulating material. The turbomolecular pump according to any one of claims 1 to 4, wherein the surface of the protective member is formed with a black nickel plating layer containing a fluororesin.