JPH0771395A - Evacuator - Google Patents

Abstract

PURPOSE: To accelerate a vent in a vacuum chamber and to shorten the rise time of a pump by forcefully vaporizing the water molecules stuck to the trap panel of a turbopump with a heating device. CONSTITUTION: When a turbopump 15 with a trap is driven to exhaust a vacuum chamber, the water moledules in gas molecules are frozen and aggregated by an annular trap panel 24, a support frame 25 and a center section trap panel 26 at the inlet of a pump case 18. If the vacuum chamber is communicated with the atmosphere at the stationary temperature when an operation under vacuum is completed and the vacuum chamber is vented to the atmospheric pressure, such a trouble occurs that the water molecules frozen on a trap panel 23 are quickly liquefied and flow back into the vacuum chamber. When a heating device 27 is provided near the intake port 21 of the turbopump 15, the trap panel 23 can be heated from the stationary temperature to the normal temperature in several minutes. The water molecules aggregated on the trap panel 23 can be quickly vaporized, the rise/fall time of the turbopump 15 can be shortened, and work efficiency can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vacuum exhaust device used for a sputtering device and other devices having a vacuum process.

[0002]

2. Description of the Related Art Vacuum devices are widely used in industrial fields such as semiconductors and optics. As an example of using an apparatus having such a vacuum process, PVD (physical vapor) is used.
deposition) method. The PVD method is a technique for forming a thin film, mainly a metal is physically deposited, and the sputtering method, which is one of the forming methods, in principle, accelerates Ar ^{+ in a} vacuum by a discharge method. It collides with an electrode (target) kept at a negative potential. According to this method, the electrode material is desorbed from the surface receiving Ar ⁺ energy (this is referred to as a sputtering phenomenon), and the protruding material is deposited on another substrate to form a thin film.

The above sputtering apparatus requires a vacuum chamber for converting thin film substances into high energy ions in vacuum. A vacuum exhaust device is required to exhaust the gas in the vacuum chamber, and a cryopump or a trap turbo pump is conventionally used for this vacuum exhaust device. An example of a cryopump system using a helium gas refrigerator will be described with reference to FIG. A cryopump 3 is connected to the vacuum chamber 1 via a conduit 8 having a main valve (high vacuum valve) 2. The cryopump 3 is connected to a rotary pump (mechanical pump) 5 via a cryoraf valve 4. A conduit 7 having a chamber rough valve 6 is led from the vacuum chamber 1 in the middle of the system, and the other end of the conduit 7 is connected to a conduit 8a connecting the cryoraf valve 4 and the rotary pump 5. It is connected. Furthermore, a pipeline 9 of another system is led out from the vacuum chamber 1 via a chamber vent valve 10 on the way.

An example of the structure of the cryopump 3 is shown in FIG. In the figure, a rotary shaft 11 connected to a Heliu gas small refrigerator (not shown) has entered a pump case 12, and a cold blade 13 is provided at the tip of the shaft. A baffle 14 is provided at the intake port of the pump case 12, and the pipe line 8 is connected to the intake port.

In the above cryopump 3, the baffle 1
4. Among the gas molecules that are cooled to a cryogenic temperature such as 4 and cold vanes 13 and enter from the gas phase through the conduit 8, water vapor or gas having a higher vapor pressure than that is the baffle 1 at the pump inlet.
4, etc. are condensed and exhausted. Lower gases such as nitrogen, oxygen, and argon are bonded to the cold blade 13,
Cold panel (not shown) for gas with lower vapor pressure
Are adhered to and are captured by the adsorbent.

In order to evacuate using the above-mentioned cryopump 3 by the vacuum evacuation system of FIG. 4, first, the chamber vent valve 10, the main valve 2 and the cryoraf valve 4 are closed, and the chamber rough valve 6 is opened. The rotary pump 5 is driven to rough the vacuum chamber 1. Next, the chamber rough valve 6 is closed and the cryopump 3 is driven to make the vacuum chamber 1 a high vacuum. In the above vacuum evacuation system, the main valve 2 and the cryoraf valve 4 are absolutely necessary due to the capability of the cryopump 3, and the chamber rough valve 6 is also necessary for rough evacuation of the vacuum chamber 1. Further, the chamber vent valve 10 is necessary regardless of the type of vacuum pump.

[0007]

Since the cryopump is a self-contained pump, the rise time from the switch ON to the start of operation (time to cool to a predetermined temperature)
Also, the fall time from the switch OFF until the operation is stopped (time to heat up to a predetermined temperature) takes 1 to 2 hours, and during that time, work is performed with the atmosphere open to the atmosphere while the vacuum chamber is in communication with the cryopump. I can't. Therefore, the main valve 2 is always required between the vacuum chamber and the cryopump.

A high-vacuum bellows valve or the like is used as the main valve 2, but the pressure difference between the high-vacuum side and the atmospheric pressure side is large, and the main valve 2 needs to be hermetically sealed. I don't get. However, when the structure of the main valve becomes complicated, the surface area of each member that constitutes the valve becomes large, and the valve is in a high vacuum, which causes dust to be generated on the surface of each member. There has been a problem that released gas is generated from the material of each member, which flows into the vacuum chamber, and prevents high vacuum inside. That is, it is ideal that there is no main valve between the vacuum chamber and the cryopump in order to create a high vacuum in the vacuum chamber. However, in the vacuum exhaust system using the cryopump of FIG. You cannot remove the valve.

On the other hand, instead of the cryopump, a trap panel is provided at the pump intake port, the trap panel is cooled, water molecules are attached to it, and a turbo pump with a trap panel (FIG. (Not shown) may be used. However, even with this turbo pump with a trap panel, it takes about 1 hour to vaporize and remove the water molecules attached to the trap and start the operation again.
In other words, to vent the vacuum chamber to atmospheric pressure,
Similar to the case of the cryopump, the trap panel has a steady temperature (that is, at a temperature at which water molecules can be adsorbed, about 100K
The temperature in the bottle must be room temperature (for example, 300K), but it takes about 1 hour.

Therefore, even when a turbo pump with a trap panel is used, a main valve is required between the vacuum chamber and the turbo pump with a trap panel, and dust generation and release from the main valve are the same as in the case of the cryopump. Problems such as gas will occur.

The present invention provides a vacuum exhaust system which solves the above problems by shortening the rise time of a turbo pump with a trap panel used as an exhaust pump and eliminating the above problems caused by removal of the main valve. To aim.

[0012]

A vacuum exhaust apparatus according to the present invention is a vacuum exhaust apparatus for exhausting gas in a vacuum chamber by an exhaust pump, the exhaust pump having a trap panel having a heating device at an intake port. It is characterized by being configured by a turbo pump. Further, the turbo pump with a trap panel may be directly connected to the vacuum chamber via a pipe line.

[0013]

According to the above construction, the water molecules attached to the trap panel of the turbo pump with the trap panel can be forcibly vaporized by the heating device in a short time, and the turbo pump can be operated to rapidly exhaust the water.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a vacuum exhaust device according to the present invention will be described below with reference to the drawings.

FIG. 1 shows a turbo pump 15 with a trap panel according to an embodiment, and FIG. 3 shows a vacuum exhaust system using the pump 15. In FIG. 3, the vacuum chamber 1 and the turbo pump 15 with a trap panel are directly connected via a pipe 16. The turbo pump 15 with a trap panel is connected to the rotary pump 5 via an auxiliary valve 17. A pipe line 9 is led out from the vacuum chamber 1 via a chamber vent valve 10.

The turbo pump 15 with a trap panel used in the above vacuum exhaust system is constructed as shown in FIG. 1 (b) is a broken side view, and FIG. 1 (a) is a vertical sectional front view of the trap panel. In each drawing, an impeller 20 integral with the main shaft portion 19 is provided in the pump case 18, an intake port 21 is provided at one end of the pump case 18, and an exhaust port is provided at the other end. ing. A flange 22 for connecting to the conduit 16 is provided on the peripheral portion of the intake port 21.

A trap panel 23 is provided inside the intake port 21 of the pump case 18. As shown in the enlarged view of FIG. 2, the trap panel 23 has an annular trap panel 24, and the inner peripheral surface of the trap panel 23 is arranged in a cross shape as seen from the front so as to intersect at the center of the intake port 21. The outer end of the frame 25 is fixed.

A central trap panel 26 is provided on the central side surface of the support frame 25. The central trap panel 26 has the same disk shape as the cross-sectional shape of the main shaft portion 19 of the impeller 20, and is provided with substantially the same size as the diameter of the main shaft portion 19. Further, the central trap panel 26 and the main shaft portion 19 are provided on the same axis. The annular trap panel 24, the support frame 25, and the central trap panel 26 are all cold panels and can trap only water molecules, and the rapid evacuation of water molecules enables reduction of the exhaust time. It is a thing. Further, other gas molecules are forcibly discharged by the impeller 20 of the turbo pump.

In the present embodiment, a heating device 27 composed of, for example, a heating coil is arranged in the space between the trap panel 23 and the intake port 21 of the pump case 18. The heating device 27 is for rapidly and forcibly evaporating the water molecules adsorbed on the trap panel 23 in a short time. Therefore, the specific configuration and arrangement position of the heating device 27 are not limited to the illustrated example.

A heat conductor 28 made of copper or the like having a high heat conductivity is coupled to the annular trap panel 24, and an end portion of the heat conductor 28 is coupled to a freezing section 30 of a refrigerator 29. ing. Then, the low temperature heat source generated in the refrigerator 29 is guided to the trap panel 23 by the heat conductor 28,
Cool it. The cooling temperature of the trap panel 23 is determined by the balance between the heat load on the trap panel 23 and the cooling capacity. The refrigerator 29 is the pump case 1
8 is attached to an end portion of a holding case 31 that is integral with 8, and the cooling unit 30 and the heat conductor 28 of the refrigerator 29 are housed in the holding case 31.

The operation of this embodiment will be described.

To perform evacuation with the vacuum evacuation system of FIG. 3, the chamber vent valve 10 is closed and the auxiliary valve 17 is used.
Is opened to drive the rotary pump 5 to perform rough evacuation of the vacuum chamber 1. At the same time, the turbo pump 15 with the trap panel and the refrigerator 29 of the trap panel 23
To drive. The turbo pump is steadily rotated in a few minutes to evacuate the inside of the vacuum chamber 1, and the trap panel 23 is brought to a steady temperature in about 1 hour to make the inside of the vacuum chamber 1 high vacuum.

When the turbo pump 15 with a trap panel is driven, as shown in FIG. 1, the rotation of the impeller 20 causes the gas molecules in the vacuum chamber 1 to be sucked into the pump case 18 from the intake port 21 and to the exhaust port. Exhausted from. At this time, water molecules that occupy an outstanding portion of the gas molecules are frozen and aggregated by the annular trap panel 24, the support frame 25, and the central trap panel 26 at the inlet of the pump case 18, and efficient exhaust is performed.

After the operation in the vacuum chamber 1 under vacuum is completed, for example, the inside of the vacuum chamber 1 is removed,
The chamber vent valve 10 may be opened to vent the vacuum chamber 1 to atmospheric pressure. In this case turbo pump 1
The trap panel 23 of No. 5 has a steady temperature (for example, 100K)
Must be at room temperature (300K) from the above, and when communicating with the atmosphere at a constant temperature, water molecules adsorbed as ice on the trap panel 23 are rapidly vaporized or liquefied and flow back into the vacuum chamber 1. Such problems occur. Therefore, conventionally, it took about 1 hour to raise the trap panel 23 from the steady temperature to the normal temperature, but according to the present embodiment, the heating device 27 is provided near the intake port 21 of the turbo pump 15. Therefore, the trap panel 23 can be heated from the steady temperature to room temperature in a few minutes. When the trap panel 23 reaches normal temperature, the auxiliary valve 17 is closed, the turbo pump 15 is turned off, and the auxiliary valve 17 is turned off.
Can be closed and the chamber vent valve 10 is opened to vent the vacuum chamber 1 to atmospheric pressure.

In the case of this embodiment, it takes about 10 minutes as described above to bring the vacuum chamber 1 into a state in which it can be vented. If you have a main valve as in the past, you do not need to wait 10 minutes, but by waiting for 10 minutes, you can omit the main valve and simplify the configuration and omit the main valve. The benefits are greater. Especially, when the vacuum performance and particles are included, the effect of omitting the main valve is immeasurable.

The configuration of each part of this embodiment may be changed in design as necessary.

[0027]

As described above, according to the vacuum exhaust apparatus of the present invention, gas molecules can be forcibly exhausted by the turbo molecular pump, and the trap panel occupies an outstanding portion of the gas molecules to be exhausted. Water molecules can be exhausted. Moreover, the heating device provided in the intake port can quickly vaporize and exhaust the water molecules condensed in the trap panel, shorten the startup and shutdown times of the turbo molecular pump, and improve the work efficiency. it can. In addition, with the shortening of the startup and shutdown times of the turbo molecular pump, it is possible to connect the turbo molecular pump directly to the vacuum chamber, and there is no problem even if the conventional main valve is omitted. Therefore, the structure can be simplified. Furthermore, by eliminating the need for the main valve, dust generation and emission gas, which are the generation sources of this main valve during vacuum, can be reduced, and clean vacuum exhaust of the vacuum chamber can be obtained.
Furthermore, since the main valve is eliminated, the conductance of the exhaust port is increased, so that the vacuum performance is improved.

[Brief description of drawings]

FIG. 1A is a vertical sectional front view of a trap panel shown in FIG. 1B, and FIG. 1B is a cutaway side view of a turbo pump with a trap panel according to an embodiment.

FIG. 2A is an enlarged perspective view of a trap panel, and FIG. 2B is a sectional view taken along line II-II of FIG. 2A.

FIG. 3 is an explanatory diagram of a vacuum exhaust system according to an embodiment.

FIG. 4 is an explanatory diagram of a conventional vacuum pumping system using a cryopump.

FIG. 5 is an explanatory cross-sectional view of a cryopump.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Vacuum chamber, 2 ... Main valve, 5 ... Rotary pump, 10 ... Chamber vent valve, 15 ... Turbo pump with trap panel, 16 ... Pipe line, 17 ... Auxiliary valve, 18 ... Pump case, 20 ... Impeller, 23 ... trap panel, 24 ... annular trap panel, 25 ... support frame, 26 ... central trap panel, 27 ... heating device,
28 ... Heat conductor, 29 ... Refrigerator.

Claims (2)

[Claims] 1. A vacuum exhaust device for exhausting gas in a vacuum chamber by an exhaust pump, wherein the exhaust pump comprises:
A vacuum evacuation device comprising a turbo pump with a trap panel having a heating device at an intake port. 2. The vacuum exhaust apparatus according to claim 1, wherein the turbo pump with the trap panel is configured to be directly connected to the vacuum chamber via a pipe line.