JP2946733B2 - Vacuum exhaust device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] A vacuum exhaust device, in particular, a vacuum exhaust device including a turbo-molecular pump, a foreline trap, and an oil rotary pump, relates to a vacuum exhaust device. An object of the present invention is to provide a vacuum exhaust device capable of shortening a standby time before starting vacuum exhaust, [1] a first exhaust path including a first trap maintained at a low temperature, A second exhaust path including a second trap that is maintained at a higher temperature than the first exhaust path, and the first exhaust path and the second exhaust path each have a valve so that the exhaust path can be switched. It is configured so that

[2] In the above [1], the first exhaust path extends from the vacuum vessel to the oil rotary pump via the turbo-molecular pump and the first trap in this order, and is connected to the turbo-molecular pump and the first trap. And a valve between the first trap and the oil rotary pump, and the second exhaust path leads from the vacuum vessel to the turbo molecular pump and the second trap in this order to the oil rotary pump. In addition, a valve is provided between the turbo molecular pump and the second trap and between the second trap and the oil rotary pump.

[3] In the above [1], the first exhaust path extends from the vacuum vessel to the oil rotary pump via the turbo-molecular pump and the first trap in this order, and between the vacuum vessel and the turbo-molecular pump. And a valve between the first trap and the oil rotary pump, the second exhaust path from the vacuum vessel to the oil rotary pump via the second trap without passing through the turbo molecular pump, Further, a valve is provided between the vacuum container and the second trap and between the second trap and the oil rotary pump.

[Industrial applications]

The present invention relates to a vacuum exhaust device, and more particularly to a vacuum exhaust device including a turbo-molecular pump, a foreline trap, and an oil rotary pump.

The turbo molecular pump is a vacuum pump in which vanes having opposite angles are alternately arranged on a stator and a rotor, and an evacuation action is obtained by rotating the rotor at a high speed.
Since it can evacuate to an ultra-high vacuum region and has a high evacuation speed, it is used for various process devices and analyzers that require an ultra-high vacuum, or a sample exchange chamber of these devices. . In these devices, vacuum destruction and vacuum evacuation are repeated relatively frequently for sample exchange and so on. It is desired that the time be as short as possible.

[Conventional technology]

An example of a conventional vacuum exhaust device will be described with reference to FIG. FIG. 5 is a schematic configuration diagram showing an example of a conventional evacuation device. In the figure, reference numeral 1 denotes a vacuum container for a vacuum exhaust,
11 is a turbo molecular pump, 12 is an oil rotary pump, 53 is a trap, 55 and 56 are valves for opening and closing a pipeline, and E is an exhaust passage.

The turbo molecular pump 11 is a main pump of the evacuation device, and the oil rotary pump 12 is an auxiliary pump. Trap 53
Is to adsorb the oil vapor generated by the oil rotary pump 12 to the adsorbent so as not to flow back into the vacuum chamber (ie, a foreline trap). This adsorbent is used by cooling it with liquid nitrogen during high vacuum, because the adsorbent improves its adsorbing capacity by cooling. Use at about room temperature because it drops rapidly. So this trap
53 is provided with a heating means (not shown). The exhaust path E is from the vacuum vessel 1 to the valve 55, the turbo molecular pump 11, the valve
56, the trap 53 and the oil rotary pump 12
Refers to the pipeline leading to

In a state where the vacuum evacuation apparatus is evacuating the vacuum vessel 1 to a high vacuum, the valve 1a is closed, the valves 55 and 56 are open, the turbo molecular pump 11 is operated (steady rotation), the oil rotary pump 12 is operated, and the trap is operated. 53 is in the state of cooling. To return the vacuum vessel 1 from high vacuum to atmospheric pressure, first, the valve 55 and the
56 is closed, then the operation of the turbo-molecular pump 11 is stopped (braking is applied), and the trap 53 stops cooling and starts heating. Thereafter, the valve 1a is opened, and the atmosphere is introduced into the vacuum vessel 1. To change the vacuum vessel 1 from atmospheric pressure to high vacuum again,
After the turbo molecular pump 11 stops and the temperature of the trap 53 rises to about room temperature, the heating of the trap 53 is stopped, and the valve 55 and
Open 56 (ie start roughing by oil rotary pump 12). Next, when the degree of vacuum of the vacuum vessel 1 reaches about 1 Torr, the cooling of the trap 53 is started, and then the operation of the turbo molecular pump 11 is started. Eventually, the turbo molecular pump 11 reaches steady rotation, and the vacuum vessel 1 is brought to a desired high vacuum.

The reason why the turbo molecular pump 11 is stopped when the evacuation of the vacuum vessel 1 is started is to prevent the turbo molecular pump 11 from being overloaded.

[Problems to be solved by the invention]

As described above, in such a conventional evacuation apparatus,
After returning the vacuum container to atmospheric pressure, the turbo-molecular pump is stopped and the next evacuation cannot be started until the temperature of the trap rises to about room temperature. The time required to stop the turbo molecular pump is about 20 minutes (when braking is performed by introducing air, the time can be reduced to about 5 minutes), but it takes 30 to 60 minutes to heat the trap to room temperature. This is because the adsorbent of the trap is granular and in a vacuum and has poor heat conduction. Therefore, in the conventional evacuation device,
After returning the vacuum container to atmospheric pressure, it is necessary to wait for a long time before starting re-evacuation, especially in applications where vacuum evacuation and vacuum destruction are frequently repeated. There was a problem that efficiency was low.

An object of the present invention is to solve such a problem and to provide a vacuum evacuation apparatus capable of shortening a waiting time until vacuum evacuation is started again after breaking a vacuum in a vacuum vessel. I do.

[Means for solving the problem]

According to the present invention, according to the present invention, there is provided [1] an apparatus for evacuating a vacuum vessel having a turbo molecular pump and an oil rotary pump, wherein the first apparatus includes a first trap maintained at a low temperature. Exhaust path, and a second exhaust path including a second trap that is maintained at a higher temperature than the first trap, the first exhaust path and the second exhaust path each has a valve [2] Further, in the above [1], the first exhaust path may be a vacuum vessel from the turbo-molecular pump, A valve is provided between the turbo molecular pump and the first trap and between the first trap and the oil rotary pump, and a valve is provided between the turbo molecular pump and the first trap. The exhaust path is from the vacuum vessel to the turbo molecular pump and the second trap. By providing a valve via these to the oil rotary pump and having a valve between the turbo molecular pump and the second trap and between the second trap and the oil rotary pump, [3] Further, in the above [1], the first exhaust path extends from the vacuum vessel to the oil rotary pump via the turbo-molecular pump and the first trap in this order, and is connected between the vacuum vessel and the turbo-molecular pump. And a valve between the first trap and the oil rotary pump, the second exhaust path from the vacuum vessel to the oil rotary pump via the second trap without passing through the turbo molecular pump, This is achieved by providing a valve between the vacuum vessel and the second trap and between the second trap and the oil rotary pump.

[Action]

The evacuation apparatus of the present invention includes two foreline traps, one of which is always cooled by liquid nitrogen (high adsorption efficiency) and the other is always kept at room temperature (low adsorption efficiency). The exhaust path can be switched so that exhaust gas passes through one side. Therefore, by using the former trap at the time of high vacuum evacuation and the latter trap at the time of rough evacuation, it is not necessary to heat the trap (reducing the adsorption efficiency) before resuming the evacuation after vacuum destruction of the vacuum vessel, Therefore, evacuation can be resumed without waiting for a long time.

Two examples of the configuration of the exhaust path of the vacuum exhaust device of the present invention and their operation will be described with reference to FIGS. 1 and 2. FIG.

FIG. 1 is a diagram (part 1) showing the basic concept of the present invention, and corresponds to claim 2 of the present invention. In the figure, the same components as those in FIG. 5 are denoted by the same reference numerals. 1 is a vacuum container,
11 is a turbo molecular pump, 12 is an oil rotary pump, 13 is a first trap, 14 is a second trap, 15 to 18 are valves, A is a first exhaust path, and B is a second exhaust path. Both the first trap 13 and the second trap are foreline traps for adsorbing oil vapor or the like of the oil rotary pump 12, and the first trap 13 is constantly cooled by liquid nitrogen and has a low temperature. The second trap 14 is always at about room temperature.
The first exhaust path A is provided from the vacuum vessel 1 to the turbo molecular pump 11,
The valve 15, the first trap 13, and the valve 16 reach the oil rotary pump 12 via these components in this order. The second exhaust path B is an oil rotary pump from the vacuum vessel 1 through the turbo molecular pump 11, the valve 17, the second trap 14, and the valve 18 in this order.
12 (from the vacuum vessel 1 to the turbo molecular pump 11 is shared with the first exhaust path A).

In a state where the evacuation apparatus is evacuating the vacuum apparatus 1 to a high vacuum, the valves 15 and 16 are opened, the valves 17 and 18 are closed, and the exhaust passes through the cooled first trap 13.
When returning the vacuum vessel 1 to the atmospheric pressure, the valves 15 to 18 are all closed, and the exhaust does not pass through any of the traps. When restarting the evacuation of the vacuum vessel 1 (at the time of rough evacuation), the valve 15
And 16 are closed, 17 and 18 are open, and the exhaust passes through a second trap 14 at room temperature.

FIG. 2 is a diagram (part 2) illustrating the basic concept of the present invention, and corresponds to claim 3 of the present invention. In the drawing, the same components as those in FIG. 1 are denoted by the same reference numerals. 25 and 27 are valves, C is a first exhaust path, and D is a second exhaust path. The first exhaust path C extends from the vacuum vessel 1 to the oil rotary pump 12 via the valve 25, the turbo molecular pump 11, the first trap 13, and the valve 16 in this order. The second exhaust path D leads from the vacuum vessel 1 to the oil rotary pump 12 via the valve 27, the second trap 14, and the valve 18 in this order (not through the turbo molecular pump 11).

In a state where the vacuum exhaust device is evacuating the vacuum device 1 to a high vacuum, the valves 25 and 16 are opened, the valves 27 and 18 are closed, and the exhaust passes through the cooled first trap 13.
When returning the vacuum vessel 1 to atmospheric pressure, the valves 25, 16, 27, and 18 are all closed, and the exhaust does not pass through any of the traps.
When the evacuation of the vacuum vessel 1 is resumed (during rough evacuation), the valves 25 and 16 are closed, and 27 and 18 are opened, and the evacuation passes through the second trap 14 at room temperature.

〔Example〕

Two embodiments of the evacuation device according to the invention are
This will be described with reference to FIGS. These are all examples applied to evacuation of a substrate exchange chamber in a molecular beam crystal growth apparatus.

FIG. 3 is an apparatus configuration diagram of the first embodiment of the present invention.
The basic structure of the exhaust passage of this device is the same as that of FIG. In the drawing, the same components as those in FIG. 1 are denoted by the same reference numerals. Reference numeral 30 denotes a substrate on which crystal growth is performed by this apparatus. Reference numeral 31 denotes a crystal growth chamber which is constantly evacuated by the ion pump 32 and maintains an ultra-high vacuum. The crystal growth chamber 31 communicates with a substrate exchange chamber 34 via a gate valve 33. This substrate exchange chamber 34 corresponds to the vacuum vessel 1 in FIG.
A valve 34a for introducing the atmosphere (corresponding to 1a in FIG. 1), a door 34b for taking the substrate 30 in and out, and the like are provided, and a transfer rod 35 is attached. At the end of the transfer rod 35, a substrate holder 36 that holds the substrate 30 is attached. This transfer rod 35
(The crystal growth chamber 31 and the substrate exchange chamber
Between 34). 37 is a gate valve for shutting off between the substrate exchange chamber 34 and the turbo molecular pump 11, and 38 is a valve for introducing the atmosphere into the turbo molecular pump 11 (normally closed).

This molecular beam crystal growth apparatus is used as follows. The crystal growth chamber 31 is constantly evacuated by the ion pump 32 to maintain an ultra-high vacuum (the gate valve 33 is normally closed).
The oil rotary pump 12 is always operating, the trap 13 is always cooled, and the trap 14 is always at room temperature. In a state where the substrate exchange chamber 34 is in a high vacuum (the turbo molecular pump 11 is constantly rotating), the gate valve 33 is
Then, the substrate 30 after the crystal growth is held from the crystal growth chamber 31 by the substrate holder 36 and moved to the substrate exchange chamber 34, and the gate valve 33 is closed. Next, close the gate valve 37 and open the valve 34
Open a, close valves 15 and 16, and open turbo molecular pump 11
Brake on At this time, the valve 38 is opened and the atmosphere is introduced into the turbo molecular pump 11 to reduce the braking time. After the pressure in the substrate exchange chamber 34 becomes atmospheric pressure, the door 34b is opened, the substrate 30 on which the crystal growth has been completed is taken out, and a new substrate 30 is inserted. Thereafter, the door 34b is closed, the valves 34a and 38 are closed, and the gate valve 37 and the valves 17 and 18 are opened to start roughing of the substrate exchange chamber 34. When the degree of vacuum in the substrate exchange chamber 34 reaches about 1 Torr, the valves 17 and 18 are closed and the valves 15 and 16 are closed.
Then, the operation of the turbo molecular pump 11 is restarted.
When the degree of vacuum in the substrate exchange chamber 34 reaches about 1 × 10 ⁻⁶ Torr, the gate valve 33 is opened to move the substrate 30 to the crystal growth chamber 31, and the gate valve 33 is closed again to start crystal growth.

The present inventor has proposed this apparatus (however, the capacity of the substrate exchange chamber 34 is 20
As a result of repeating the crystal growth of the substrate, the time required from the start of the introduction of the air into the substrate exchange chamber 34 to the completion of the exchange of the substrate 30 is about 5 minutes. Turbo molecular pump 11 braked at the start
The time required to stop the rotation was about 5 minutes. Therefore, five minutes after the start of the introduction of the atmosphere into the substrate exchange chamber 34, the next evacuation (rough evacuation) could be started with zero standby time. In the conventional molecular beam crystal growth apparatus, it took about 40 minutes to heat the cooled trap and raise the temperature to room temperature, during which time rough evacuation could not be started. That is, the required time was reduced by 35 minutes, and the processing capacity of the molecular beam crystal growth apparatus was greatly improved.

FIG. 4 is an apparatus configuration diagram of a second embodiment of the present invention.
The basic structure of the exhaust passage of this device is the same as that of FIG. In the drawing, the same components as those in FIGS. 2 and 3 are denoted by the same reference numerals. The difference of this apparatus from the first embodiment is that a valve 27 is attached to the substrate exchange chamber 34, and an exhaust passage for roughing is provided from the substrate exchange chamber 34 to the valve 2.
7, the second trap 14 and the valve 18 in this order only reach the oil rotary pump 12 via these. Also, the second
The valve 25 in the figure has been replaced by a gate valve 37,
A valve 15 is added between the turbo molecular pump 11 and the first trap 13, but since the valve 15 is normally opened, the basic configuration is the same as that of FIG.

The difference in use of this device from the first embodiment described above is that
The point that the operation of the turbo molecular pump 11 is continued when the vacuum in the substrate exchange chamber 34 is broken (the valve 38 is not opened and the valve 15 is not closed), and the valve 27 is opened without opening the gate valve 37 at the start of roughing. The only difference is that the valve 27 is closed and the gate valve 37 is opened when the roughing is completed.

In this apparatus, similarly to the apparatus of the first embodiment, the time required from the start of introduction of the air into the substrate exchange chamber 34 to the completion of the exchange of the substrate 30 is about 5 minutes. After 5 minutes from the start of the introduction of the air into the chamber, the next evacuation (rough evacuation) can be started with no waiting time.

The present invention is not limited to the above embodiments, and can be implemented in various modifications. For example, the present invention can be applied to various apparatuses other than the molecular beam crystal growth apparatus.

〔The invention's effect〕

As described above, according to the present invention, it is possible to provide a vacuum evacuation apparatus capable of shortening the waiting time until the vacuum evacuation is started again after breaking the vacuum in the vacuum vessel. Operation efficiency is improved.

[Brief description of the drawings]

 FIG. 1 is a diagram showing the basic concept of the present invention (No. 1), FIG. 2 is a diagram showing the basic concept of the present invention (No. 2), and FIG. FIG. 4 is an apparatus configuration diagram of a second embodiment of the present invention, and FIG. 5 is an apparatus configuration diagram showing an example of a conventional apparatus. In the figure, 1 is a vacuum vessel, 1a is a valve, 11 is a turbo molecular pump, 12 is an oil rotary pump, 13 is a first trap, 14 is a second trap, 15 to 18, 25, 27 are valves, A, C is a first exhaust path, and B and D are second exhaust paths.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F04B 37/16

Claims (3)

(57) [Claims] An apparatus for evacuating a vacuum vessel having a turbo-molecular pump and an oil rotary pump, comprising: a first exhaust path including a first trap maintained at a low temperature; A second exhaust path including a second trap maintained at a higher temperature than the trap of the first exhaust path, the first exhaust path and the second exhaust path each having a valve and an exhaust path An evacuation apparatus characterized by being configured to be switchable. 2. The first exhaust path leads from the vacuum vessel to the turbo-molecular pump, the first trap, and the oil rotary pump via the first trap in this order. A valve is provided between the trap and the first trap and the oil rotary pump, and the second exhaust path is provided by the vacuum vessel, the turbo-molecular pump, and the second trap in this order. Via the oil rotary pump, and valves between the turbo molecular pump and the second trap and between the second trap and the oil rotary pump. Claim 1
The vacuum evacuation device as described. 3. The first exhaust path leads from the vacuum vessel to the oil rotary pump via the turbo-molecular pump and the first trap in this order, and is connected to the vacuum vessel and the turbo-molecular pump. And a valve between the first trap and the oil rotary pump, and the second exhaust path passes through the second trap from the vacuum vessel without passing through the turbo-molecular pump. And a valve between the vacuum vessel and the second trap and between the second trap and the oil rotary pump. Item 7. An evacuation apparatus according to Item 1.