JP5330896B2 - Dry vacuum pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dry vacuum pump which can prevent a defective function of a drive source caused by hydrogen contained in gas to be exhausted. <P>SOLUTION: The dry vacuum pump 1 includes an electromagnetic motor 3 stored in an electromagnetic motor chamber 10, a shaft 5 rotatively driven by the electromagnetic motor 3, and a rotor 6 attached to the shaft 5, provided in an exhaust chamber 13, and sucking and discharging the gas to be exhausted containing hydrogen gas in a vacuum treating chamber 103 into the exhaust chamber 13, and is provided with a purge mechanism 40 for introducing an inert gas into the electromagnetic motor chamber 10, and exhausting the gas in the electromagnetic motor chamber 10. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a dry vacuum pump that exhausts a vacuum processing chamber.

  The dry vacuum pump has a structure in which a liquid such as oil does not come into contact with the gas to be exhausted therein, and is often used when high in-system cleanliness is required in the semiconductor manufacturing field or the like. There are many types of dry vacuum pumps, but it is common to exhaust a system by rotating a rotor that sucks and discharges a gas to be exhausted by rotational power generated by a power source such as an electromagnetic motor ( For example, see Patent Document 1).

On the other hand, in recent years, development and production of silicon-based thin film solar cells have been actively performed. For this type of thin film production, an amorphous silicon or crystalline silicon thin film is formed on a substrate by using a plasma CVD technique using silane (SiH ₄ ) and hydrogen gas (H ₂ ) as main source gases. The technique to do is common (for example, refer patent document 2).

JP 2005-171766 A JP 2006-216922 A

In the plasma CVD apparatus for manufacturing a thin film as described above, a mixed gas of silane gas and hydrogen gas is mainly used as a source gas when forming an amorphous silicon film or a crystalline silicon thin film. Further, in a vacuum processing chamber (film forming chamber or the like) of the plasma CVD apparatus, hydrogen gas is also generated by a decomposition reaction of silane. Therefore, the exhaust target gas (exhaust gas) exhausted from the vacuum processing chamber contains a large amount of hydrogen gas.
On the other hand, a dry vacuum pump used for sucking and discharging a gas to be exhausted including hydrogen gas from a vacuum processing chamber includes an electromagnetic motor as a drive source thereof, and the electromagnetic motor includes a permanent magnet material as a constituent material. . Permanent magnet materials are typically iron-neodymium-based materials, and permanent magnet materials are prone to rust due to moisture, so corrosion resistance has been improved by nickel plating or the like. In addition, it is known that permanent magnet materials absorb hydrogen, so they form hydrogen compounds and become brittle due to heat generation, etc., leading to a decrease or collapse of magnetic force. There is a concern that the excitation power will be reduced.
Furthermore, since hydrogen gas has a small molecular size and is easy to diffuse, the hydrogen gas diffuses from the exhaust chamber of the dry vacuum pump to the inside of the electromagnetic motor through the seal portion of the rotating shaft of the rotor, and further to the surface of the permanent magnet. It has been found that there is a risk of causing erosion by hydrogen through the thin nickel plating and plating pinholes applied to.

Therefore, when a dry vacuum pump is used as an evacuation means of a vacuum processing chamber (film forming chamber or the like) of a plasma CVD apparatus for thin film production, the permanent motor of an electromagnetic motor by a large amount of hydrogen gas contained in an exhaust gas (exhaust gas). Avoiding the malfunction of the magnet material is an important issue. Therefore, a countermeasure for preventing the permanent magnet material and the hydrogen gas from coming into direct contact is desired.
In particular, when a film is formed on a large area substrate exceeding 1 m ² under a high dilution rate film forming condition in which a silane gas is diluted with a large amount of hydrogen gas as seen in the production of a crystalline silicon-based thin film, a vacuum exhaust is performed. Since the ratio of hydrogen gas in the exhaust target gas to the pump internal capacity increases, there is a concern that the permanent magnet material malfunction of the electromagnetic motor due to the hydrogen gas may further occur.

  In view of the circumstances as described above, the present invention provides a dry vacuum pump that can prevent malfunction of a drive source (electromagnetic motor) due to hydrogen gas contained in an exhaust target gas (exhaust gas) guided from a vacuum processing chamber. The purpose is to provide.

In order to solve the above problems, the dry vacuum pump of the present invention employs the following means.
That is, a dry vacuum pump according to the present invention includes an electromagnetic motor housed in an electromagnetic motor chamber, a shaft that is rotationally driven by the electromagnetic motor, and a hydrogen that is attached to the shaft and provided in the exhaust chamber, In a dry vacuum pump for exhausting a vacuum processing chamber having a rotor for sucking and exhausting a gas to be exhausted including gas into the exhaust chamber, an inert gas is introduced into the electromagnetic motor chamber, A purge means for exhausting the gas is provided.

Hydrogen gas erodes the permanent magnet material of the electromagnetic motor and degrades the magnetic performance. If the gas to be exhausted contains hydrogen gas, the exhaust chamber and the electromagnetic motor chamber are connected via the shaft, so that hydrogen may enter the electromagnetic motor chamber from the exhaust chamber.
Therefore, in the present invention, a purge means for introducing an inert gas into the electromagnetic motor chamber and exhausting the gas in the electromagnetic motor chamber is provided. As a result, even if hydrogen gas enters the electromagnetic motor chamber, it can be exhausted, and the introduction of inert gas lowers the hydrogen gas partial pressure, so that a large amount of hydrogen erodes the permanent magnet material of the electromagnetic motor. There is nothing. Therefore, it can avoid that the permanent magnet of an electromagnetic motor is eroded by hydrogen gas.

  Furthermore, according to the dry vacuum pump of the present invention, a lubrication chamber for storing lubricating oil is provided between the exhaust chamber and the electromagnetic motor chamber, and is introduced into the electromagnetic motor chamber by the purge means. The inert gas is exhausted after passing through the lubrication chamber.

  First, the exhaust target gas containing hydrogen gas enters the lubrication chamber adjacent to the exhaust chamber. An inert gas introduced from the electromagnetic motor chamber is introduced into the lubrication chamber and exhausted. Thus, the hydrogen gas encounters the inert gas in the lubrication chamber and is exhausted before entering the electromagnetic motor chamber. Therefore, it is possible to prevent hydrogen gas from entering the electromagnetic motor chamber as much as possible.

  The dry vacuum pump of the present invention includes an electromagnetic motor housed in an electromagnetic motor chamber, a shaft that is rotationally driven by the electromagnetic motor, and a hydrogen gas that is attached to the shaft and provided in the exhaust chamber, A vacuum processing chamber having a rotor for sucking and exhausting a gas to be exhausted into the exhaust chamber and a lubrication chamber provided between the exhaust chamber and the electromagnetic motor chamber for storing lubricating oil. In the dry vacuum pump, a purge means is provided for introducing an inert gas into the lubrication chamber from the outside of the electromagnetic motor chamber and exhausting the gas in the lubrication chamber by a gas introduction passage formed in the shaft. It is characterized by that.

Hydrogen gas erodes the permanent magnet material of the electromagnetic motor and degrades the magnetic performance. If the gas to be exhausted contains hydrogen gas, the exhaust chamber, the lubrication chamber, and the electromagnetic motor chamber are connected via the shaft, so hydrogen may enter the electromagnetic motor chamber from the exhaust chamber via the lubrication chamber. There is.
Therefore, in the present invention, a purge means is provided for introducing an inert gas into the lubrication chamber from the outside of the electromagnetic motor chamber by a gas introduction passage formed in the shaft and exhausting the gas in the lubrication chamber. Thereby, even if hydrogen gas enters the lubrication chamber from the exhaust chamber, the hydrogen gas can be exhausted before entering the electromagnetic motor chamber, and the hydrogen gas partial pressure is reduced by introducing the inert gas. A large amount of hydrogen does not erode the permanent magnet material of the electromagnetic motor. Therefore, it can avoid that the permanent magnet of an electromagnetic motor is eroded by hydrogen gas.
In addition, since the inert gas is introduced into the lubrication chamber from the outside of the electromagnetic motor chamber by the gas introduction passage formed in the shaft, the inert gas can be introduced into the lubrication chamber without drawing the piping into the electromagnetic motor chamber. And a simple configuration is realized.

  Further, according to the dry vacuum pump of the present invention, the purge means includes a gas discharge passage connected to an exhaust line for exhausting the exhaust target gas from the exhaust chamber, and the exhaust line includes the exhaust line. A check valve is provided which allows a gas flow toward the opposite direction and prohibits a reverse flow.

  By providing the check valve, it is possible to prevent the exhaust target gas discharged from the exhaust chamber to the exhaust line from entering the lubrication chamber or the electromagnetic motor chamber through the gas discharge passage.

  Further, according to the dry vacuum pump of the present invention, the purge means includes a gas discharge passage connected to an exhaust line for exhausting the exhaust target gas from the exhaust chamber, and the exhaust line includes the exhaust line. An oil trap is provided for capturing the lubricating oil toward the head.

  By providing the oil and the lap, the lubricating oil can be prevented from leaking into the exhaust line together with the purge gas, and a clean exhaust system can be maintained.

  According to the dry vacuum pump of the present invention, since the inert gas is introduced into the electromagnetic motor chamber and the purge means for exhausting the gas in the electromagnetic motor chamber is provided, the permanent magnet of the electromagnetic motor is eroded by hydrogen gas. Can be avoided, and malfunction of the electromagnetic motor can be prevented.

It is the schematic block diagram which showed the vacuum processing system | strain in which the dry vacuum pump which concerns on 1st Embodiment of this invention is used. It is the plane sectional view showing the internal structure of the dry vacuum pump of FIG. It is the sectional side view which showed the internal structure of the dry vacuum pump of FIG. It is sectional drawing which showed the structure of the exhaust chamber of the dry vacuum pump of FIG. It is an expanded sectional view which shows the detail of the cup seal of the dry vacuum pump of FIG. The structure of the sealing member which comprises the cup seal of FIG. 5 is shown, (A) is a cross-sectional perspective view, (B) is sectional drawing which showed the effect | action of the principal part of a sealing member. It is the expanded sectional view which showed the detail of the cup seal of FIG. It is the sectional side view which showed the internal structure of the dry vacuum pump which concerns on 2nd Embodiment of this invention.

  Embodiments according to the present invention will be described below with reference to the drawings.

[First Embodiment]
FIG. 1 shows an outline of a vacuum processing system using the dry vacuum pump 1 according to the first embodiment of the present invention.
A plasma CVD apparatus (vacuum processing apparatus) 101 includes a film forming chamber 103, and a dry vacuum pump 1 is provided in a system for evacuating the film forming chamber 103. The film forming chamber 103 forms a film on a large area glass substrate (not shown) exceeding 1 m ² . In the film forming chamber 103, gas supply channels 104 and 105 for supplying silane gas (SiH ₄ ), hydrogen gas (H ₂ ), and cleaning gas (NF ₃ ), which are main source gases, into the film forming chamber 103, respectively. , 106 are connected. The film forming chamber 103 is provided with an exhaust system 61 for exhausting gas.
The exhaust system 61 includes an exhaust passage 110 provided with a high vacuum turbo molecular pump (TMP) 109 and a passage 112 provided with a flow rate adjusting valve (CV) 111. A dry vacuum pump (DP) 1 is interposed in the flow path 113 downstream from the junction S of the exhaust flow path 110 and the flow path 112. Further, an exhaust line 62 is provided on the downstream side of the dry vacuum pump 1. The exhaust line 62 includes a combustible exhaust line 117 that exhausts a combustible gas such as silane gas and hydrogen gas, and a combustion support exhaust line 118 that exhausts a combustion support gas such as nitrogen trifluoride gas (NF ₃ ). Branch off. The combustible exhaust line 117 is provided with a combustible exhaust valve 119a, and the combustion supporting exhaust line 118 is provided with a combustion supporting exhaust valve 119b.
When supplying silane gas and hydrogen gas as raw material gases for film formation, the combustible exhaust line 117 is used with the combustible exhaust valve 119a opened and the combustion support exhaust valve 119b closed.
When supplying nitrogen trifluoride gas as a cleaning gas for self-cleaning the film forming chamber 103, the combustible exhaust valve 119a is closed, the combustion supporting exhaust valve 119b is opened, and the combustion supporting exhaust line 118 is opened. Use.
Further, the plasma CVD apparatus 101 is provided with a vacuum gauge (V) 120 for measuring the pressure in the film forming chamber 103.

In the plasma CVD apparatus 101 configured as described above, a film-forming gas containing a source gas made of SiH ₄ is sent into the film-forming chamber 103 decompressed from the atmospheric pressure while performing roughing vacuum evacuation by the dry vacuum pump 1, Plasma is generated by high-frequency power supplied from a high-frequency power source (not shown), and a film is formed on a substrate such as glass that is supported and heated in the film-forming chamber 103. As a board | substrate, the large area glass substrate exceeding 1 m < ² > is mentioned, for example.
The source gas is diluted with hydrogen gas. For example, for forming a crystalline silicon film, the film quality can be improved by diluting the hydrogen gas 20 times or more with respect to the silane gas.

When the plasma CVD apparatus 101 receives an instruction for a film forming process, the MV 121 and the TV 122 are opened, the RV 123 is closed, and the turbo molecular pump 109 and the dry vacuum pump 1 perform high vacuum evacuation.
A substrate (not shown) is set in the film forming chamber 103, receives a film forming recipe instruction, and performs a film forming process according to the film forming recipe.
For example, in the formation of the crystalline silicon film, the film forming pressure is 1000 to 3000 Pa for obtaining the film forming speed of 2.0 to 2.5 nm / s, and the silane gas that is the film forming raw material gas per 1 m ^{2 of} the substrate is used. The flow rate is 0.5 to 2.0 SLM / m ² , and the hydrogen gas flow rate is 10 SLM / m ² or more.

Next, the MV 121 and the TV 122 are closed and the RV 123 is opened, and the raw film forming gas is introduced into the film forming chamber 103 while performing roughing vacuum evacuation by the dry vacuum pump 1 and measured by the vacuum gauge (V) 120. The flow regulating valve (CV) 111 is adjusted so that the pressure in the film forming chamber 103 is equal to the pressure in the film forming chamber 130 of the film forming recipe instruction value, and the pressure in the film forming chamber 103 is adjusted.
Next, plasma discharge is started, thereby forming a film.
After the predetermined film formation is performed, the plasma discharge is stopped and the film forming raw material gas is stopped. The MV 121 and the TV 122 are opened and the RV 123 is closed, high vacuum evacuation is performed by the turbo molecular pump 109 and the dry vacuum pump 1, the film-formed substrate is carried out, and the film-forming process is completed.
The dry vacuum pump 1 may be used by improving the vacuum exhaust capability by combining a mechanical booster pump such as a roots pump and an exhaust system in series.

FIG. 2 is a plan cross-sectional view of the dry vacuum pump 1 according to the present embodiment as viewed from above. FIG. 3 shows a side sectional view of the dry vacuum pump 1 as seen from the side.
The dry vacuum pump 1 according to the present embodiment is configured as a roots type dry vacuum pump, but the present invention is not limited to this, and for example, other types of dry vacuum such as a scroll type, a rotary blade type, etc. It can also be applied to mechanical booster pumps such as pumps and roots pumps.

  As shown in the figure, the dry vacuum pump 1 includes an electromagnetic motor 3 as a drive source, a lubrication chamber 12 disposed on the side of the electromagnetic motor 3, and an exhaust disposed on the side of the lubrication chamber 12. And a seal mechanism 11 disposed between the lubrication chamber 12 and the exhaust chamber 13.

  The lubrication chamber 12 is formed by the motor cover 8 and the side cover 9, and the exhaust chamber 13 is formed by the cylinder 7 and the side cover 9. The lubrication chamber 12 and the exhaust chamber 13 constitute a main housing part of the dry vacuum pump 1.

  The lubrication chamber 12 accommodates the rotation transmission mechanism 4, and the exhaust chamber 13 accommodates the first rotor (rotor) 6. The electromagnetic motor 3 is disposed adjacent to the motor cover 8. A first shaft (shaft) 5 is connected to the rotating shaft of the electromagnetic motor 3. The first shaft 5 passes through the lubrication chamber 12 and extends through the side cover 9 to the exhaust chamber 13. The location where the first shaft 5 communicates with the lubrication chamber 12 and the exhaust chamber 13 is such that the first seal mechanism 11 suppresses the movement of gas between the lubrication chamber 12 and the exhaust chamber 13 as the first shaft 5 rotates. Is sealed. The rotation transmission mechanism 4 is connected to the first shaft 5 in the lubrication chamber 12, and the first rotor 6 is connected to the first shaft 5 in the exhaust chamber 13. The lubricating chamber 12 contains lubricating oil F (see FIG. 3) for lubricating the rotation transmission mechanism 4.

  In addition to the above configuration, the dry vacuum pump 1 according to the present embodiment includes a second shaft (shaft) 14, a second rotor (rotor) 15, and a second seal mechanism 16 (see FIG. 2). The second shaft 14 is connected to the rotation transmission mechanism 4 in the lubrication chamber 12 and extends through the side cover 9 to the exhaust chamber 13 in parallel with the first shaft 5. The location where the second shaft 14 communicates with the lubrication chamber 12 and the exhaust chamber 13 is such that the second seal mechanism 16 suppresses the movement of gas between the lubrication chamber 12 and the exhaust chamber 13 as the second shaft 14 rotates. Is sealed. A second rotor 15 is connected to the second shaft 14 in the exhaust chamber 13.

  Further, the dry vacuum pump 1 according to the present embodiment has a bearing chamber 17 on the opposite side (right side in FIG. 2) of the exhaust chamber 13 when viewed from the lubrication chamber 12. The bearing chamber 17 is formed by a second side cover 18 attached to the side opposite to the side cover 9 of the cylinder 7 and a bearing cover 19 attached to the second side cover 18. The first shaft 5 and the second shaft 14 pass through the second side cover 18 and are rotatably supported in the bearing chamber 17. The bearing chamber 17 accommodates a first bearing 20 that rotatably supports the first shaft 5 and a second bearing 21 that rotatably supports the second shaft 14. The first bearing 20 and the second bearing 21 are, for example, ball bearings.

The electromagnetic motor 3 is accommodated in the electromagnetic motor chamber 10 and generates rotational power for rotating the first rotor 6. The electromagnetic motor 3 may have a general structure as a power source for the dry vacuum pump 1. Typically, the electromagnetic motor 3 has a stator and a rotor, and a permanent magnet material is used for either the stator or the rotor. The permanent magnet material is preferably relatively inexpensive and possesses strong magnetic properties. For example, a rare earth magnet is used. As the permanent magnet material, for example, a rare earth iron-based magnet material such as iron-neodymium-based material is used, and in order to improve durability against erosion due to formation of rust, corrosion, or a hydrogen compound that absorbs hydrogen on the surface of the magnet body. A plating layer made of metal such as nickel is applied.
As shown in FIGS. 2 and 3, the electromagnetic motor 3 and the lubrication chamber 12 are provided on the side where the gas is compressed in the exhaust space 26 of the exhaust chamber 13 (the side close to atmospheric pressure). By arranging the electromagnetic motor 3 in this way, airtight management of the electromagnetic motor chamber 10 can be facilitated. In addition, when pressure fluctuations occur, such as when the dry vacuum pump 1 is started and stopped, the pressure difference between the lubrication chamber 12 and the exhaust chamber 13 is small, so that the effect of further ensuring the sealing characteristics in the first seal mechanism 11 is obtained. is there.
The number of electromagnetic motors 3 is not limited to one, and a plurality of electromagnetic motors may be provided.

  The rotation transmission mechanism 4 is lubricated by the lubricating oil F, transmits the rotational power generated by the electromagnetic motor 3 to the first shaft 5 and the second shaft 14, and synchronizes the first rotor 6 and the second rotor 15 in opposite directions. Rotate. The rotation transmission mechanism 4 includes a first timing gear 22, a second timing gear 23, a first bearing 24 and a second bearing 25. The first timing gear 22 is attached to the first shaft 5 and transmits rotational power to the second timing gear 23. The first bearing 24 includes an outer ring fixed to the side cover 9, an inner ring fixed to the first shaft 5, and a bearing ball disposed therebetween, and the first shaft 5 can be rotated to the side cover 9. To support. The second timing gear 23 is attached to the second shaft 14, receives rotational power from the first timing gear 22, and rotates the second shaft 14. The second bearing 25 includes an outer ring fixed to the side cover 9, an inner ring fixed to the second shaft 14, and a bearing ball disposed therebetween, and the second shaft 14 can rotate to the side cover 9. To support. The structure of the rotation transmission mechanism 4 is not limited to these, For example, a reduction gear etc. may be included.

  The first rotor 6 and the second rotor 15 rotate to suck and discharge the exhaust target gas. FIG. 4 is a cross-sectional view showing the configuration of the first rotor 6 and the second rotor 15. As shown in FIGS. 2 and 3, the first rotor 6 is arranged in series along the shaft 5 in multiple stages (six stages in the illustrated example), and the second rotor 15 is arranged in series along the second shaft 14. They are arranged in multiple stages (six stages in the illustrated example).

  The first rotor 6 at each stage is arranged in pairs with the second rotor 15 at each stage. Each of the first rotor 6 and the second rotor 15 is formed in a three-leaf shape, and when the first shaft 5 and the second shaft 14 are rotated, they can be rotated with a small distance from the paired rotor portions. It has become.

  Each pair of the first rotor 6 and the second rotor 15 is disposed in a pair of six exhaust spaces 26 formed in the cylinder 7, and the exhaust spaces 26 are sequentially connected by an exhaust passage 26 a that communicates with the exhaust space in the subsequent stage. Has been. Further, the exhaust space 26 in the foremost stage (uppermost stream stage) is connected to an intake hole 7 a formed in the cylinder 7, and the exhaust space 26 in the last stage (most downstream stage) is connected to an exhaust hole 7 b formed in the cylinder 7. (See FIG. 3).

The intake hole 7a is connected via an exhaust system 61 to a film forming chamber 103 of a plasma CVD apparatus as a vacuum processing chamber for manufacturing a thin film. The exhaust hole 7 b is connected to each exhaust line 62. The film forming chamber 103 is configured as a film forming chamber for forming an amorphous silicon film or a crystalline silicon film on a substrate. In the film forming chamber 103, the film forming chamber mainly containing silane gas (SiH ₄ ) and hydrogen gas (H ₂ ) is formed into the film forming chamber whose pressure is reduced from the atmospheric pressure while performing roughing vacuum evacuation by the dry vacuum pump 1. Gas is fed in and plasma is generated by high-frequency power supplied from a high-frequency power source (not shown) to form a film on a substrate such as glass that is supported and heated in the film-forming chamber 103. At this time, a large amount of hydrogen gas is exhausted to the exhaust line 62 by the dry vacuum pump 1 by decomposing silane gas (SiH ₄ ) and introducing a large amount of hydrogen gas (H ₂ ) into the film forming chamber 103.
Since a large amount of hydrogen gas (H ₂ ) is supplied to the substrate preheating chamber in addition to the film forming chamber 103, it can be used similarly.

For example, for the formation of a crystalline silicon film, the distance d between the plasma discharge electrode that supplies high frequency power of 40 MHz to 100 MHz and the substrate surface is set to 3 mm to 10 mm, and hydrogen gas is diluted 20 times or more with respect to silane gas. By supplying the raw material gas, the film forming speed and the film quality can be improved. More than 1 m ² in the formation of large-area substrate crystalline silicon film, in order to obtain a deposition rate 2.0~2.5nm / s, a deposition pressure 1000～3000Pa, for deposition per substrate 1 m ² The flow rate of the silane gas that is the raw material gas is 0.5 to 2.0 SLM / m ² , and the flow rate of the hydrogen gas is 20 SLM / m ² or more, which is approximately 20 to 100 SLM / m ² . A part of the silane gas is consumed for film formation, so that hydrogen gas generated by decomposition of the silane gas is also added, the flow rate of the hydrogen gas exhausted to the exhaust line 62 is further increased, and the hydrogen gas partial pressure in the exhaust target gas is It is very big.

  The first seal mechanism 11 and the second seal mechanism 16 seal the conduction between the lubricating oil F and the exhaust target gas at a location where the first shaft 5 and the second shaft 14 communicate with the lubrication chamber 12 and the exhaust chamber 13. The side cover 9 is formed with a gas introduction hole 9a for supplying a seal gas to the location.

Next, the first seal mechanism 11 and the second seal mechanism 16 will be described.
Since the first seal mechanism 11 and the second seal mechanism 16 have the same configuration, the first seal mechanism 11 will be described.
FIG. 5 is a cross-sectional view showing the configuration of the first seal mechanism 11, and is an enlarged view of the vicinity of the first seal mechanism 11 of FIG.

As shown in the figure, the first seal mechanism 11 has a first seal (lubricating chamber side seal) 27 and a second seal (exhaust chamber side seal) 28. The first seal 27 is disposed between the side cover 9 and the first shaft 5, and the second seal 28 is disposed between the cylinder 7 and the first shaft 5.
A gap G communicating with the gas introduction hole 9 a is formed between the cylinder 7 and the side cover 9, and a gas introduction space 29 is formed by the first seal 27 and the second seal 28. In the dry vacuum pump 1 according to the present embodiment, portions of the side cover 9 and the cylinder 7 facing the gas introduction space 29 constitute a partition wall.
In addition to the above configuration, the first seal mechanism 11 has a slinger 30 attached to the first shaft 5 in the lubrication chamber 12.

  The 1st seal | sticker 27 and the 2nd seal | sticker 28 have the respectively same structure, for example, is comprised by the sealing member A shown to FIG. 6 (A). FIG. 6 is a perspective view showing the configuration of the seal member A. FIG. The seal member A is configured by an annular cup seal (lip seal) whose inner peripheral portion elastically contacts the outer periphery of the shaft 5.

As shown in FIG. 6A, the seal member A includes a fixed part a, a base part b, and two lip parts c. A fixed portion a is formed on the outer peripheral side of the annular seal member A, a base b is formed so as to protrude from the fixed portion a in the radial direction of the ring, and the two directions are inclined with respect to the radial direction from the base b The two lip portions c are formed so as to protrude in the direction of (2). In other words, the pair of lip portions c have a structure that projects in opposite directions while being along the axial direction of the first shaft 5. The lip c is formed to be elastically deformable so as to approach or separate from the other lip c.
The seal member A may be composed of a plurality of members.

The fixed part a, the base part b, and the lip part c are formed of a material such as fluorine rubber that has resistance to the exhaust gas including hydrogen and the lubricating oil F and has elasticity.
Further, the seal member A has a sliding member d disposed at a position where each lip portion c contacts the first shaft 5 and a support member e inserted into the fixed portion a and the base portion b.

  The sliding member d is made of a material having a low friction coefficient such as polytetrafluoroethylene, for example, reduces the contact resistance between the seal member A and the first shaft 5, and makes the gap between the first shaft 5 uniform. Since the friction coefficient is low, it is preferable because the amount of wear of the sliding member d can be reduced and reliability can be secured over a long period of time. FIG. 6B is a diagram showing the configuration of the sliding member d. As shown in the figure, after the seal member A is attached to the dry vacuum pump 1 as the first seal 27 and the second seal 28, the dry vacuum pump 1 is idled, so that each sliding member d has a shaft. 5 and is used in a state in which the caddy portion having a high surface pressure of the sliding member d is smoothed as shown in the figure below.

  The support member e is made of metal, for example, and maintains the strength and shape of the seal member A. The support member e may be omitted.

FIG. 7 is a longitudinal sectional view showing the arrangement of the first seal 27 and the second seal 28.
As shown in the figure, the first seal 27 is disposed between the side cover 9 and the first shaft 5 and mainly prevents leakage of the lubricating oil F (or its vapor) from the lubrication chamber 12 to the exhaust chamber 13. Has a function to regulate. The second seal 28 is disposed between the cylinder 7 and the first shaft 5, and mainly has a function of restricting invasion of gas to be exhausted (particularly hydrogen gas) from the exhaust chamber 13 to the lubrication chamber 12.

  The first seal 27 is fixed to the side cover 9, the second seal 28 is fixed to the cylinder 7, and the fixed portions a are fixed. The lip portions c are in elastic contact with the first shaft 5.

  Of the two lip portions c of the first seal 27, the lip portion c facing the lubrication chamber 12 is a first lip 31, and the lip portion c facing the gas introduction space 29 is a second lip 32. Of the two lip portions c of the second seal 28, the lip portion c facing the gas introduction space 29 is a third lip 33, and the lip portion c facing the exhaust chamber 13 is a fourth lip 34.

  The first lip 31 moves closer to the first shaft 5 when the pressure in the lubrication chamber 12 is higher than the gas introduction space 29, and the first shaft 5 when the pressure in the lubrication chamber 12 is lower than the gas introduction space 29. It is possible to elastically deform in the direction away from the. Similarly, the second lip 32, the third lip 33, and the fourth lip 34 are relatively low in the direction of approaching the first shaft 5 when the pressure in the space facing each lip is relatively high. In this case, it can be elastically deformed in a direction away from the first shaft 5.

  The slinger 30 rotates with the first shaft 5 and suppresses the liquid lubricating oil F from reaching the first seal 27 due to centrifugal force. In addition, the arrangement of the slinger 30 is arbitrary.

Next, the purge mechanism (purge means) 50 will be described.
As shown in FIG. 3, the purge mechanism 40 includes a gas introduction part 50 and a gas discharge passage 53. The purge mechanism 40 is for diluting hydrogen in the exhaust target gas leaked into the lubrication chamber 12 through the seal mechanisms 11 and 16 with an inert gas and does not react with the gas component of the exhaust target gas. Is used. As the inert gas, nitrogen gas such as nitrogen gas or argon gas is preferable because it is inexpensive and has a large molecular weight even if mixed in the exhaust chamber 13, so that a reduction in exhaust capability of the dry vacuum pump can be suppressed to a small extent. In this embodiment, nitrogen gas is used.

  The gas introduction part 50 is formed in part in a container of the electromagnetic motor chamber 10 that houses the electromagnetic motor 3, and is introduced into the internal space of the electromagnetic motor 3. One end of the gas introduction unit 50 is connected to a nitrogen gas introduction source 51 installed outside the electromagnetic motor chamber 10. Thereby, the nitrogen gas introduced from the nitrogen gas introduction source 51 is introduced into the lubrication chamber 12 from the internal space of the electromagnetic motor 3 via the gas introduction part 50. Nitrogen gas is always introduced into the lubrication chamber 12 from the internal space of the electromagnetic motor 3 during the operation of the dry vacuum pump 1. Thereby, the internal space of the electromagnetic motor 3 and the lubrication chamber 12 are always maintained in a nitrogen gas atmosphere.

  The internal space of the electromagnetic motor 3 having the gas introduction part 50 is connected to the motor cover 8 that partitions the lubrication chamber 12, and the other end of the gas discharge passage 53 is connected to the exhaust line 62. The gas discharge passage 53 passes nitrogen gas (purge gas) introduced into the lubrication chamber 12, seal gas introduced from the gas introduction space 29 and leaked into the lubrication chamber 12, and exhaust target gas leaked into the lubrication chamber 12 into the exhaust line 62. It is for discharging.

  The purge mechanism 40 further includes a check valve 54 and an oil trap 55. The check valve 54 and the oil trap 55 are each installed in the gas discharge passage 53.

  The check valve 54 allows a gas flow from the lubrication chamber 12 toward the exhaust line 62 and prohibits the reverse flow. This prevents the gas to be exhausted from the film forming chamber (vacuum processing chamber) 103 discharged from the exhaust hole 7 b of the exhaust chamber 13 from entering the lubrication chamber 12 through the gas discharge passage 53.

  The oil trap 55 is provided in the middle of the gas discharge passage 53 between the lubrication chamber 12 and the check valve 54. The oil trap 55 includes the nitrogen gas (purge gas) discharged from the lubrication chamber 12, the seal gas introduced from the gas introduction space 29 and leaked into the lubrication chamber 12, and the exhaust target gas leaked into the lubrication chamber 12. This is to prevent the lubricating oil F from carrying over and entering the exhaust line 62. As the oil trap 55, an appropriate one such as a filter or a water-cooled trap can be used.

  The dry vacuum pump 1 of the present embodiment is configured as described above. Next, the operation of the dry vacuum pump 1 will be described.

  When the electromagnetic motor 3 starts rotating, the first shaft 5 connected to the electromagnetic motor 3 rotates, and the first timing gear 22 rotates accordingly. The second timing gear 23 is rotated by the first timing gear 22, and the second shaft 14 connected to the second timing gear 23 rotates. That is, the first shaft 5 and the second shaft 14 rotate in the reverse direction at the same speed. As the first shaft 5 and the second shaft 14 rotate, the first rotor 6 and the second rotor 15 rotate.

  Inside the lubrication chamber 12, the first timing gear 22, the second timing gear 23, the first bearing 24 and the second bearing 25 are lubricated by the lubricating oil F.

  When the first rotor 6 and the second rotor 15 rotate, a region in which the volume is expanded and a region in which the volume is compressed are formed in each exhaust space 26. For this reason, gas is sucked from the exhaust passage on the side where the volume is expanded, and the gas is discharged to the exhaust passage on the side where the volume is compressed. Thereby, in each exhaust space 26, the exhaust gas containing hydrogen is sucked from the film forming chamber 103 through the upstream exhaust space 26 or the intake hole 7a, and the gas is discharged into the subsequent exhaust space 26 or the exhaust hole 7b. The Since the gas is compressed in each exhaust space 26 sequentially than the exhaust space 26 in the previous stage, even if the pressure in the exhaust target system is sufficiently lower than the atmospheric pressure, the exhaust can be finally pressurized to the atmospheric pressure or exhausted. Is possible. In this case, particularly in a situation where the pressure in the exhaust target system is high, such as at the start of exhaust, the gas may be pressurized to atmospheric pressure or higher in the region where the volume is compressed.

As described above, the film forming chamber 103 is evacuated to a predetermined vacuum level or maintained at a predetermined vacuum level. As will be described later, since the dry vacuum pump 1 of the present embodiment includes the first seal mechanism 11 and the second seal mechanism 16, it is possible to prevent the lubricating oil F or its vapor from being mixed into the exhaust target gas, Suppresses contamination in the exhaust target system. Further, since the exhaust target gas in the exhaust chamber 13 is suppressed from entering the lubrication chamber 12, the electromagnetic motor 3 is suppressed from being exposed to the exhaust target gas. Thereby, even when a large amount of hydrogen is contained in the exhaust target gas, it is possible to suppress the deterioration of the permanent magnet material constituting the electromagnetic motor 3.
The first seal mechanism 11 and the second seal mechanism 16 supply the seal gas and have a pair of lip portions c that extend in opposite directions while being along the axial direction of the shaft, so that the exhaust target gas can be in the lubrication chamber. The electromagnetic motor 3 is further effectively prevented from entering the gas 12 and being exposed to the exhaust target gas.

  Next, the operation of the first seal mechanism 11 will be described. The operation of the second seal mechanism 16 is the same as that of the seal mechanism 11.

When the gas introduction space 29 is filled with the seal gas, the pressure of the gas introduction space 29 increases. As the seal gas (seal gas supply source), an inert gas that does not react with the gas component of the exhaust target gas is used. Inert gas includes nitrogen gas and argon gas, but the price of nitrogen gas is low, and even if mixed into the exhaust chamber 13, the molecular weight is large, so the reduction in exhaust capacity of the dry vacuum pump can be suppressed to a minimum. preferable.
By introducing the seal gas, the gas introduction space 29 is adjusted to a flow rate that is higher than the maximum pressure of the exhaust space 26 to be described later (pressure at which a sufficient flow rate of seal gas is obtained).

  When the first shaft 5 rotates, with respect to the first seal 27, the seal gas is caught in the sliding portion between the second lip 32 and the first shaft 5 to push up the second lip 32, and the seal gas is discharged from the formed gap. Leaks. The seal gas that has flowed out is further wound around the sliding portion between the first lip 31 and the first shaft 5 to push up the first lip 31, and the seal gas flows out into the lubrication chamber 12 through the formed gap. That is, the seal gas is ejected from the gas introduction space 29 through the gap between the first seal 27 and the first shaft 5 into the lubrication chamber 12.

  Also for the second seal 28, when the first shaft 5 rotates, the seal gas is caught in the sliding portion between the third lip 33 and the first shaft 5 to push up the third lip 33 and seal gas from the formed gap. Leaks. The seal gas that has flowed out is further caught in the sliding portion between the fourth lip 34 and the first shaft 5 to push up the fourth lip 34, and the seal gas flows out from the formed gap. That is, the seal gas is ejected from the gas introduction space 29 to the exhaust chamber 13 through the gap between the second seal 28 and the first shaft 5.

  Thus, the lubricating oil F and its vapor in the lubrication chamber 12 are sealed by the seal gas ejected from the gap between the first seal 27 and the gap between the second seal 28 formed between the first shaft 5 and the first seal 5. It is possible to more effectively prevent the gas to be exhausted in the exhaust chamber 13 from passing through the second seal 28 and entering the gas introduction space 29.

  On the other hand, depending on the pressure relationship between the exhaust chamber 13 and the gas introduction space 29, or the pressure relationship between the gas introduction space 29 and the lubrication chamber 12, hydrogen from the film forming chamber 103 sucked into the exhaust chamber 13 is removed. There is a possibility that the gas to be exhausted may enter the lubrication chamber 12 through the seal mechanisms 11 and 16. In this case, the exhaust target gas including hydrogen gas that has entered the lubrication chamber 12 comes into contact with the electromagnetic motor 3, and the permanent magnet material constituting the electromagnetic motor 3 erodes by contact with the hydrogen gas, and the excitation force is caused by destruction or the like. There is concern about the decline. In this case, the function as a drive source of the dry vacuum pump 1 is deteriorated, and in the worst case, the function is malfunctioned.

  In order to prevent this, in the present embodiment, during the operation of the dry vacuum pump 1, the purge mechanism 40 reduces the hydrogen concentration of the exhaust target gas that has entered the lubrication chamber 12, thereby adversely affecting the electromagnetic motor 3 described above. Try to avoid. That is, in this embodiment, during the operation of the dry vacuum pump 1, the purge gas (nitrogen gas) is introduced from the nitrogen gas introduction source 51 through the gas introduction unit 50 into the internal space of the electromagnetic motor 3 and the lubrication chamber 12. The purge gas thus discharged is discharged to the exhaust line 62 through the gas discharge passage 53. As a result, the internal space of the electromagnetic motor 3 and the inside of the lubrication chamber 12 can be maintained in a nitrogen gas atmosphere, and even if an exhaust gas including hydrogen gas enters the lubrication chamber 12 via the seal mechanisms 11 and 16, The hydrogen gas concentration in the internal space of the motor 3 and in the lubrication chamber 12 can be suppressed to a predetermined value or less.

In the present embodiment, the flow rate of nitrogen gas, which is a purge gas introduced into the internal space of the electromagnetic motor 3 and the lubrication chamber 12, is selected, for example, by mixing helium into the exhaust target gas and the internal space of the electromagnetic motor 3 or the lubrication chamber. It is possible to select an appropriate flow rate by connecting a helium leak detector in 12 and measuring a change in the concentration of helium.
In this embodiment, when the nitrogen gas flow rate as the purge gas introduced through the gas introduction unit 50 is changed from 1 SLM to 3 SLM and the concentration of helium is measured by the helium leak detector, the nitrogen gas flow rate is 1.0 SLM or more. As a result, the helium concentration became a very low and constant concentration. For this reason, 1.0 SLM was selected in order to effectively use nitrogen gas.
The flow rate of the purge gas is not particularly limited, and can be set to an appropriate value in consideration of the internal space of the electromagnetic motor 3 and the volume of the lubrication chamber 12, the amount of hydrogen gas entering the lubrication chamber 12, and the like.

  In the present embodiment, since the check valve 54 having the above-described configuration is installed in the gas discharge passage 53, the gas to be exhausted from the film forming chamber 103 discharged to the exhaust line 62 through the exhaust hole 7b. Intrusion into the lubrication chamber 12 through the gas discharge passage 53 is prevented. Thereby, the nitrogen gas atmosphere in the lubrication chamber 12 can be maintained.

  Further, in the present embodiment, since the oil trap 55 is installed in the gas discharge passage 53, the lubricating oil F in the lubricating chamber 12 is prevented from being discharged together with the purge gas to the exhaust line 62. Thereby, the contamination of the exhaust line 62 due to oil can be prevented, and a clean exhaust system can be constructed.

[Second Embodiment]
In the second embodiment, a gas introduction passage 52 is provided in the gas introduction part 50 of the first embodiment, and the description of the same parts as those in the first embodiment is omitted.
As shown in FIG. 8, the purge mechanism (purge means) 40 includes a gas introduction passage 52 and a gas discharge passage 53. The purge mechanism 40 is for diluting hydrogen in the exhaust target gas leaked into the lubrication chamber 12 through the seal mechanisms 11 and 16 with an inert gas, and a case where nitrogen gas is used as the inert gas. explain.

The gas introduction passage 52 is formed in the rotating shaft (rotor) of the electromagnetic motor 3 and the shaft center portion of the shaft 5. One end of the gas introduction passage 52 is connected to a nitrogen gas introduction source 51 installed outside the electromagnetic motor 3 through a gas introduction portion 50 formed in the container of the electromagnetic motor chamber 10, and the other end of the gas introduction passage 52. Faces the outer periphery of the shaft 5 located in the lubrication chamber 12. Thereby, the nitrogen gas introduced from the nitrogen gas introduction source 51 is introduced into the lubrication chamber 12 through the gas introduction passage 52. Nitrogen gas is always introduced into the lubrication chamber 12 during the operation of the dry vacuum pump 1. Thereby, the lubrication chamber 12 is always maintained in a nitrogen gas atmosphere.
In addition, between the gas introduction part 50 and the gas introduction passage 52 of the axial end part of the shaft 5 is installed with a small gap so that the shaft 5 can rotate. Most of the purge gas introduced from the gas introduction unit 50 may be introduced into the gas introduction passage 52 and a part of the interior of the electromagnetic motor chamber 10 may be purged.

  One end of the gas discharge passage 53 is connected to the motor cover 8 that partitions the lubrication chamber 12, and the other end of the gas discharge passage 53 is connected to the exhaust line 62. The gas discharge passage 53 supplies nitrogen gas (purge gas) introduced into the lubrication chamber 12, seal gas introduced from the gas introduction space 29 and leaked into the lubrication chamber 12, and exhaust target gas leaked into the lubrication chamber 12 into the exhaust line 62. It is for discharging.

In the second embodiment, since the gas introduction passage 52 is provided in the rotating shaft of the electromagnetic motor 3 and the axial center portion of the shaft 5, it is not necessary to install a pipe around the electromagnetic motor 3. There is an advantage. Further, since nitrogen gas is directly introduced from the periphery of the rotating shaft 5 into the lubrication chamber 12, the periphery of the shaft 5 can always be covered with nitrogen gas, and the exhaust target including hydrogen into the electromagnetic motor 3 can be obtained. This has the advantage that gas can be effectively prevented from entering. Hydrogen gas in the exhaust target gas leaked from the exhaust chamber to the lubrication chamber through the seal mechanisms 11 and 16 is directly diluted by the purge mechanism, and hydrogen of the exhaust target gas including hydrogen gas leaked from the exhaust chamber side to the lubrication chamber Since the gas partial pressure is also lowered, it becomes possible to more effectively prevent the permanent magnet material constituting the electromagnetic motor 3 from being eroded by hydrogen.
Thus, the malfunction of the drive source due to hydrogen contained in the exhaust gas can be prevented.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made based on the technical idea of the present invention.
For example, in the above-described embodiment, the seal installed between the lubrication chamber 12 and the exhaust chamber 13 is configured by the seal mechanisms 11 and 16 having the above-described configuration. However, the seal is not limited thereto, and the end surface is a circular O-ring. You may comprise the said seal | sticker. Further, in the seal mechanisms 11 and 16, the arrangement of the second seal 28 on the exhaust chamber 13 side may be omitted.

DESCRIPTION OF SYMBOLS 1 Dry vacuum pump 3 Electromagnetic motor 4 Rotation transmission mechanism 5 Shaft 6,15 Rotor 11,16 Seal mechanism 12 Lubrication chamber 13 Exhaust chamber 40 Purge mechanism 50 Gas introduction part 51 Purge gas (nitrogen gas) introduction source 52 Gas introduction passage 53 Gas discharge Passage 54 Check valve 55 Oil trap 61 Exhaust system 62 Exhaust line 101 Vacuum processing equipment (plasma CVD equipment)
103 Vacuum processing chamber (film forming chamber)
104, 105, 106 Gas supply flow path
DESCRIPTION OF SYMBOLS 110 Exhaust flow path 111 Flow control valve 112,113 Flow path 117 Flammable exhaust line 118 Combustion exhaust line 120 Vacuum gauge F Lubricating oil

Claims (4)

An electromagnetic motor housed in the electromagnetic motor chamber;
A shaft rotationally driven by the electromagnetic motor;
A rotor attached to the shaft and provided in the exhaust chamber, for sucking and exhausting an exhaust target gas including hydrogen gas in the vacuum processing chamber into the exhaust chamber;
In a dry vacuum pump equipped with
A purge means is provided for introducing an inert gas into the electromagnetic motor chamber and exhausting the gas in the electromagnetic motor chamber ,
Between the exhaust chamber and the electromagnetic motor chamber, a lubrication chamber for storing lubricating oil is provided,
The dry vacuum pump characterized in that the inert gas introduced into the electromagnetic motor chamber by the purge means passes through the lubrication chamber and is exhausted . An electromagnetic motor housed in the electromagnetic motor chamber;
A shaft rotationally driven by the electromagnetic motor;
A rotor attached to the shaft and provided in the exhaust chamber, for sucking and exhausting an exhaust target gas including hydrogen gas in the vacuum processing chamber into the exhaust chamber;
A lubrication chamber provided between the exhaust chamber and the electromagnetic motor chamber and storing lubricating oil;
In a dry vacuum pump equipped with
A dry means characterized in that an inert gas is introduced into the lubrication chamber from the outside of the electromagnetic motor chamber by a gas introduction passage formed in the shaft, and a purge means for exhausting the gas in the lubrication chamber is provided. Vacuum pump. The purge means includes a gas discharge passage connected to an exhaust line for exhausting the gas to be exhausted from the exhaust chamber, and the gas discharge passage allows a gas flow toward the exhaust line and in a reverse direction. The dry vacuum pump according to claim 1 or 2, wherein a check valve for prohibiting the flow is provided. The purge means includes a gas exhaust passage connected to an exhaust line for exhausting the exhaust target gas from the exhaust chamber, and the gas exhaust passage is provided with an oil trap for capturing the lubricating oil toward the exhaust line. The dry vacuum pump according to any one of claims 1 to 3 , wherein the dry vacuum pump is provided.

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