JP2635062B2 - Particle collection device for evacuation system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a vacuum installed between a vacuum chamber and a vacuum pump to collect fine particles such as dust existing in the vacuum chamber before reaching the vacuum pump. The present invention relates to a particulate collection device for an exhaust system.

[Prior art] Conventionally, in a device such as CVD (chemical vapor deposition) that generates a large amount of fine particles (powder) such as dust, a mesh is interposed in an exhaust passage to protect a vacuum pump. A method of adhering fine particles such as dust.
However, in a vacuum, the number of Reynolds nozzles was small, and the above-described method almost relied on the Brownian effect, resulting in poor collection efficiency.

As a means for overcoming the above-mentioned disadvantages, for example, a thermophoretic trapping device as shown in FIG. 3 has been proposed (Japanese Patent Application No. 62-97521).

The collecting device shown in FIG. 3 has an outer cylindrical body 1 and an inner cylindrical body 2.
The inflow pipe 4 provided in the double cylindrical container 3 is connected via a valve 5 to, for example, a vacuum chamber 6 of a film forming apparatus. An outflow pipe 7 provided in the cylindrical container 3 is connected via a valve 8 to a vacuum pump 9 capable of forming a low or medium vacuum, and an inflow pipe between the outer cylindrical body 1 and the inner cylindrical body 2. A gas flow passage 10 is formed from the gas flow passage 4 to the outflow pipe 7. The outer cylinder 1 is provided with a heater 11 on its outside to function as a high-temperature wall, and the inner cylinder 2 has a cooling water pipe 12 inside.
By supplying cooling water through the, it functions as a low-temperature wall, reduces the pressure difference required to pass through the collection device, and collects all the fine particles in the gas.
The outer cylindrical body 1 and the inner cylindrical body 2 are configured to appropriately maintain the cross-sectional area and length. In FIG. 2, reference numeral 13 denotes a bypass pipe connecting the vacuum chamber 6 and the vacuum pump 9 via valves 14 and 15.

When the vacuum pump 9 is operated in the trapping device thus configured, the gas in the vacuum chamber 6 flows through the inflow pipe 4, the gas flow path 10 in the double cylindrical container 3 and the outflow pipe 7. The gas flow path 10 is drawn by the vacuum pump 9 because the high-temperature wall and the low-temperature wall are provided to face each other and the gas flow path 10 has a larger cross-sectional area than the inflow pipe 4. The fine particles such as dust in the gas move through the flow path 10 having a temperature gradient between the high temperature wall and the low temperature wall from the high temperature side to the low temperature side at a certain speed due to a thermophoretic phenomenon and move to the low temperature wall, that is, the inner cylindrical body 2. Adheres to Since the moving speed of the fine particles becomes the same speed with a smaller temperature gradient as the pressure is lower, the distance between the outer cylindrical body 1 and the inner cylindrical body 2 is increased, and when the temperature gradient is reduced, Even when the cross-sectional area is increased, the fine particles in the gas can be sufficiently adsorbed and collected on the low-temperature wall. In addition, since the cross-sectional area of the flow path is larger than the cross-sectional area of the inflow pipe 4, a pressure difference for collecting fine particles can be small, and therefore, it can be used for a vacuum pump capable of obtaining a relatively high degree of vacuum. It is possible to reduce the pressure in the room.

[Problems to be Solved by the Invention] The trapping device using thermophoresis proposed earlier has many advantages such as higher efficiency than the conventional one, but some particles such as dust adhere to it. Then, it was necessary to clean, and for that purpose, it was necessary to disassemble and remove fine particles.

However, gases used in processes that easily generate dust and other powders, such as in semiconductor manufacturing equipment, are very active and highly reactive, so they are usually all harmed to the final stage to ensure safety. Equipment is provided.

In such a system, if the gas is adsorbed unreacted together with fine particles such as dust, it is extremely dangerous to disassemble the device and expose it to the atmosphere. For this reason, unreacted active components are usually sufficiently purged using N ₂ gas or the like. Therefore, there is a problem that it takes much time to remove the fine particles such as the adsorbed dust.

Therefore, the present invention solves the above-mentioned problems of the conventional thermophoretic collection device, and can sufficiently collect fine particles such as dust in a low-pressure gas without increasing the pressure difference. The object of the present invention is to provide an easy-to-maintain fine particle collection device for a vacuum exhaust system that can use a vacuum pump that is easy to manufacture and can obtain a relatively high degree of vacuum and that can remove adsorbed fine particles without having to disassemble the device. And

[Means for Solving the Problems] In order to solve the above-mentioned problems, the particle collecting apparatus for an evacuation system according to the present invention is connected between a vacuum chamber and a vacuum pump, and is sucked by a vacuum pump. Particles in the gas
At a high flow rate, a gas flow into the thermophoretic particle trap is transferred to the thermophoretic particle trap, which is moved by a thermophoretic phenomenon in a flow path having a temperature gradient between the high temperature wall and the low temperature wall so as to adhere to the low temperature wall. A gas flow generator to be blown in and a discharge pipe for discharging the gas flow blown from the gas flow generator are connected via valves.

[Operation] In the thus configured particulate collection device for a vacuum exhaust system of the present invention, when cleaning of the thermophoretic fine particle trap is required, the vacuum chamber side and the vacuum pump side of the thermophoretic fine particle trap are disposed. With each valve closed and the thermophoretic particle trap disconnected, a low flow rate is achieved by blowing into the thermophoretic particle trap at a high flow rate (at least 10 m / sec) from the gas flow generator attached via the valve. Fine particles such as dust adhering to the wall are removed by the wind power together with the gas, and can be discharged from an exhaust pipe attached via a valve. The gas stream containing fine particles and gas such as dust discharged through the discharge pipe can be conveyed to the abatement apparatus and processed.

After performing the cleaning operation in this way, the valves of the gas flow generator and the discharge pipe are closed, and the valves on the vacuum chamber side and the vacuum pump side of the thermophoretic fine particle trap are opened again to recycle dust and the like generated by the thermophoretic fine particle trap. The operation of collecting fine particles can be started.

As described above, in the apparatus of the present invention, at the stage where a large amount of fine particles such as dust generated in a film forming process such as CVD adhere to the low-temperature wall of the collector, the valve of the vacuum chamber and the pipe line communicating with the vacuum pump are closed. By opening the valves of the gas flow generator and the conduit leading to the discharge pipe, a large amount of fine particles such as dust adhering to the cold wall can be removed without disassembling the apparatus.

Embodiment An embodiment of the present invention will be described below with reference to FIGS. 1 and 2 of the accompanying drawings.

FIG. 1 schematically shows a main part of a particle trapping device for an evacuation system according to one embodiment of the present invention. The particle trap body is substantially the same as the thermophoretic particle trap shown in FIG. It has a structure, and the corresponding parts are indicated by the reference numerals used in FIG. That is, in the apparatus shown in FIG. 1, the thermophoretic particle trap main body is composed of a double cylindrical container 3 composed of an outer cylindrical body 1 and an inner cylindrical body 2.
A gas flow passage 10 communicating from the inflow pipe 4 to the outflow pipe 7 is formed between the inner cylindrical body 2 and the inner cylindrical body 2. The outer cylindrical body 1 is provided with a heater 11 on its outer side to function as a high-temperature wall. The cylindrical body 2 functions as a low-temperature wall by supplying cooling water to the inside of the cylindrical body 2 through a cooling water pipe 12, reduces the pressure difference required to pass through the collection device, and removes all the fine particles in the gas. The outer cylindrical body 1 and the inner cylindrical body 2 are configured so as to appropriately maintain the cross-sectional area and length so as to be collected. That is, the gas flow path 10 is provided with the high-temperature wall and the low-temperature wall opposed to each other and has a larger cross-sectional area than the inflow pipe 4. It moves at a certain speed due to the thermophoresis phenomenon from the high temperature side to the low temperature side in the flow path 10 and adheres to the low temperature wall, that is, the inner cylindrical body 2.

In the present invention, a blower 17 is connected via a valve 16 to the upper part of the thermophoretic particle trap main body thus configured, and the blower 17 allows the gas flow path 10 in the trap main body.
The air is blown at a high flow rate. A discharge pipe 19 is connected to the bottom of the trap body via a valve 18, and the discharge pipe 19 is connected to a suitable abatement device (not shown).
Connected to.

In the operation of the illustrated embodiment configured as described above, when a large amount of fine particles such as dust in the gas sucked from the vacuum chamber adhere to the low-temperature wall and it becomes necessary to clean the inside of the trap body, evacuation is performed. The valves 5 and 8 of the system are closed to disconnect the trap body from the evacuation system. In this state, the valve 16 on the blower side and the valve 18 on the discharge pipe side are opened, and the airflow is blown into the flow path 10 in the trap body by the blower 17. In this case, the air flow blown into the flow path 10 in the trap main body provides a flow velocity (for example, 10 m / m) that gives a sufficient force to peel off fine particles such as dust attached to the low-temperature wall.
sec or more). Flow path 1 in the trap body
Fine particles such as dust peeled off from the low-temperature wall by the air flow blown into 0 are carried along the air flow from the bottom of the trap body through the discharge pipe 19 to the abatement apparatus.

FIG. 2 shows a modification of the present invention which can be advantageously used when fine particles such as dust to be handled are not dangerous. In this modification, a blower 20, a valve 21, a trap body 22, a valve 23 and a filter 24 are shown. The filter 24 removes fine particles such as dust, which are peeled off by an air flow blown into the trap body 22 from the blower 20.

By the way, in the illustrated embodiment, the trap body has a double cylindrical structure, but any type of thermophoresis type can be used.

Further, instead of the blower, for example, a high-pressure gas source filled with a high-pressure gas may be used, and a wind force may be generated by a pressure difference, and the gas may be blown at a certain wind speed or more.

Further, although air is used as the cleaning gas in the illustrated embodiment, an inert gas such as nitrogen can be preferably used.

[Effect of the Invention] As described above, according to the fine particle trapping device for a vacuum exhaust system of the present invention, the gas blown into the thermophoretic fine particle trap at a high flow rate into the thermophoretic fine particle trap By providing a cleaning system including a flow generator and a discharge pipe for discharging the gas flow blown from the gas flow generator, the cleaning system can be easily set to a cleaning mode by switching a valve. The inside can be cleaned safely and in a short time without having to disassemble the trap itself.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a main part of a particle collecting apparatus for an evacuation system according to one embodiment of the present invention, FIG. 2 is a schematic diagram showing a modification of the present invention, and FIG. It is a schematic sectional drawing which shows the principal part of the collection device performed. In the figure 1: Outer cylinder (hot wall) 2: Inner cylinder (cold wall) 3: Double cylindrical vessel (trap) 10: Gas flow path 16: Valve 17: Blower 18: Valve 19: Discharge pipe 20: Blower 21: Valve 22: Trap body 23: Valve 24: Filter

Claims (4)

(57) [Claims] A fine particle in a gas which is connected between a vacuum chamber and a vacuum pump and which is sucked by the vacuum pump is moved by a thermophoresis phenomenon in a flow path having a temperature gradient between a high temperature wall and a low temperature wall. A thermophoretic fine particle trap to be attached to the cold wall, a gas flow generator connected to the thermophoretic fine particle trap via a valve, and blowing a gas flow into the thermophoretic fine particle trap at a high flow rate; A discharge pipe connected to the thermophoretic particle trap via a valve and configured to discharge a gas flow blown from the gas flow generation device, wherein the particle collection device for a vacuum exhaust system is provided. 2. The particle collecting apparatus for an evacuation system according to claim 1, wherein the gas flow generator for blowing a gas flow into the thermophoretic particle trap at a high flow rate comprises a blower. 3. The vacuum exhaust system according to claim 2, wherein a discharge pipe for discharging a gas flow blown from the blower into the thermophoretic particle trap is connected to the blower through a filter device. Particle collecting device. 4. A particle collecting apparatus for an evacuation system according to claim 1, wherein the gas flow generator for blowing a gas flow into the thermophoretic particle trap at a high flow rate comprises a high-pressure inert gas source.