JPH0733862Y2 - Gas supply device for vacuum chamber - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention relates to a gas supply device for supplying gas to a vacuum chamber, and more particularly, to various gases introduced into the vacuum chamber or various gases for processing. The present invention relates to a gas supply device suitable for removing foreign matter such as moisture and dust.

[Prior Art] When the vacuum pressure is reduced to 10 ^-4 to 10 ^-5 Torr,
The gas molecules adhering to or occluding on the inner surface of the container jump out into the container, and the gas molecules released from the surface inhibit the pressure from decreasing. As a means for artificially releasing the gas early, there is baking, and a method of raising the temperature of the container to release the gas quickly is adopted.

However, considering the desorption rates of various gases, many gases such as H ₂ , O ₂ , CH ₄ etc.
It is 0 ^-12 to 10 ^-13 (seconds), whereas H ₂ O is on the order of 10 ^-6 (seconds), while at 150 ° C, desorption in gases such as H ₂ , O ₂ and CH ₄ While the speed is almost the same as above,
For H ₂ O, it will be on the order of 10 ^-8 (seconds). Therefore, the baking is effective for releasing H ₂ O from the surface quickly, and the baking effect is relatively small for many other gases.

Therefore, in order to quickly reduce the vacuum pressure in the chamber or the like, it is necessary to reduce H ₂ O in the chamber as much as possible. Especially, H ₂ O is about 10 ⁶ of H ₂ , O ₂ , CH _4, etc. at room temperature.
It is clear that it is necessary to reduce the amount of H ₂ O, because double the amount is attached to the wall surface and it takes about 10 ⁶ times to reach the pump from the wall surface. Therefore, when gas (air) is supplied when the chamber is returned from vacuum to atmospheric pressure for the purpose of loading and unloading products, etc., water is removed, or when supplying the necessary gas to the vacuum chamber, the gas is supplied while dehumidifying. It is effective to always supply a gas containing a small amount of H ₂ O to the chamber in order to accelerate the pressure drop.

Further, in the case of manufacturing a semiconductor in vacuum, if H ₂ O is present, it is decomposed into H ₂ and O _2, and the Si wafer produces SiO ₂ due to the O _2, so the purity decreases, Therefore, it is necessary to remove H ₂ O also from this point of view. H
_As a means to reduce the amount of ₂ O, it is often difficult to avoid H ₂ O contamination during transportation from the gas manufacturer to the use point. It is necessary not to introduce H ₂ O into the chamber at all times.

[Problems to be Solved by the Invention] An object to be solved by the present invention is to provide a gas supply device for a vacuum chamber capable of rapidly reducing the vacuum pressure.

[Means for Solving the Problems] In order to solve the above problems, the present invention provides a vacuum chamber,
In a gas supply device for a vacuum chamber, which comprises a supply pipeline for supplying gas to the vacuum chamber, the supply pipeline includes:
A heat-insulating cold material container filled with a cold material, a closed container made of a material having good thermal conductivity that is immersed in the cold material in the cold material container, and an outer peripheral edge directly fixed to the closed container. It is characterized in that a cooling dehumidifier having a plurality of stages of sintered metal filters for removing water from the gas flowing in the closed container by cooling adsorption and liquefaction is provided.

[Operation and Effect of Invention] The gas supplied to the vacuum chamber through the supply pipeline flows through the closed container in the cooling / dehumidifier provided in the supply pipeline, and the closed container and a plurality of stages are provided in the closed container. Cooled by the sintered metal filter, moisture in the gas is removed together with dust by adsorption and liquefaction by the filter, and the gas from which these are removed is supplied to the vacuum chamber.

Therefore, since the gas supplied to the vacuum chamber does not contain moisture, the vacuum chamber can be quickly lowered to a desired vacuum pressure when the vacuum is re-established.

In this case, since the outer peripheral edges of the stages of the sintered metal filters having good thermal conductivity are directly attached to the closed container, these filters are quickly cooled by the cooling material, and therefore, in a short time. Not only can the work be started, but the temperature drop can increase the adsorption efficiency of water.

In addition, since the gas supplied to the cooling dehumidifier passes through the fine gaps of the sintered metal filter provided in multiple stages many times, gas molecules have a high probability of colliding with the filter. Ability is improved.

[Embodiment] FIG. 1 shows an embodiment of the present invention, in which a vacuum chamber 1, a vacuum chamber 1, an exhaust pipe line 2 for making an ultrahigh vacuum, and a chamber 1 are brought to atmospheric pressure. A supply pipe line 3 for returning is provided, and a vacuum valve 4, an appropriate vacuum pump 5 and a valve 6 are sequentially connected to the exhaust pipe line 2 from the chamber 1 side, and the supply pipe line 3 is cooled as described later. The dehumidifier 11 and the gas valves 8 and 8 before and after it are connected.

The cooling dehumidifier 11, which is shown in detail in FIG. 2, includes a heat-insulating cold material container 13 filled with a cold material 12 such as liquid nitrogen and Freon, and a sealing container 14 which is immersed in the cooling material 12, and is hermetically sealed. The inlet pipe 15 and the outlet pipe 16 for supplying and discharging the gas to and from the container 14 have a tip extending outside the device through a hole formed in the heat insulating lid 17 of the cold material container 13,
It is connected to the supply line 3.

The closed container 14 is formed of a material having good heat conduction such as stainless steel or aluminum alloy, and a plurality of filters 19a, 19b, 19c are provided in the direction substantially orthogonal to the gas flow direction, and the containers 19 By fixing the inner wall of 14 in close contact, they are joined so as to maintain good heat conductivity.

The above filter has a mesh close to the mean free path of the purified gas by sintering fine particles or fibers of a metal having good heat conductivity such as stainless steel or brass, or by sintering a composite material thereof. It is molded into. Specifically, in consideration of easiness in production, the particles or fibers may be configured to have a fluid passage gap of about several μm, but for example, a smaller gap of 1 μm or less (preferably 0.1 μm or less). μm) is desirable.

The plurality of filters 19a, 19b, 19c are the filters 1 on the gas inflow side.
It is preferable that the mesh of 0a is coarse and the mesh is finer in order toward the filter 19c on the gas outflow side, and particularly the filter on the gas inflow side that adsorbs a large amount of water is preferably coarse.

The airtight container 14 has a heater 20 for heating by passing a heating fluid, and is heated under high vacuum in advance before starting the work to sufficiently release the water content inside.

In the cooling dehumidifier having such a configuration, a cold material container
When 13 is filled with the cooling material 12 such as liquid nitrogen, the temperature of the closed container 14 rapidly decreases from the outer periphery toward the centers of the filters 19a, 19b, 19c. When the gas is supplied from the supply line 3 at the time when the filters 19a, 19b, 19c are sufficiently cooled, the gas passes through the filters 19a, 19b, 19c, and is an impurity gas (vapor having a higher vaporization temperature than that of the cooling material 12). ) Is liquefied (adsorbed) and collected by the filters 19a, 19b, 19c, and the clean gas from which the impurity gas, water and dust are removed flows into the vacuum chamber 1 through the supply pipe line 3.

Therefore, since the gas supplied to the vacuum chamber 1 does not contain water, when the vacuum is re-evacuated, the vacuum chamber 1
It is possible to shorten the time required to reduce the pressure to an extremely high vacuum.

In this case, the lower the temperature, the better the adsorption of molecules, so that the adsorption efficiency can be increased by the excellent thermal conductivity of the filters 19a, 19b, 19c. In addition, since the gas to be purified passes through the micron-sized gaps in the filters 19a, 19b, 19c made of sintered metal hundreds of times, the gas molecules have a high probability of colliding with the inner wall of the filter and have a good collection ability. .

Further, if the filter is made of stainless steel, it is possible to dehumidify corrosive gas and remove dust.

According to the experiments by the present inventors, in order to return the vacuum to the atmospheric pressure,
When the atmosphere with a humidity of 45% is introduced into the chamber, Fig. 5A
As shown in, it takes about 800 minutes to exhaust the chamber again to the 10 ^-9 Torr level, while introducing nitrogen gas containing 10 to 20 PPM of water after baking at 150 ° C for 24 hours. In the case of introducing the nitrogen gas after dehumidifying by the cooling dehumidifier 11 (below the measurement limit of 1 PPM of the commercially available measuring instrument) after the same baking for about 120 minutes as shown in FIG. As shown in, the exhaust time was drastically shortened to about 11 minutes.

The cooling dehumidifier 11 is a type of device that accumulates impurities and the like removed by the filter. Therefore, when continuously purifying gas, install two or more devices and use one dehumidifier. While the impurities are being removed, the other closed container 14 is heated by the heater 20 in the container and sucked by a vacuum pump to dehumidify and purify the inside. Again, the filter
Since it has good heat conduction to 19a, 19b, 19c, it is heated rapidly,
The time required for dehumidifying the closed container 14 can be shortened.

The cooling dehumidifier 11 is a total cooling type that cools the entire hermetically sealed container 14, but liquid nitrogen is used as the cooling material 12, whereby when purifying nitrogen gas, the cooling material and the gas to be purified are When the liquefaction temperature is the same or almost the same, if the cooling capacity of the filter is large, the gas to be purified (nitrogen gas) may be liquefied in the closed container 14 and may not flow to the outlet pipe 16. Further, at this time, if the cold material 12 in the cold material container 13 is exhausted, the liquefied gas in the closed container 14 may be vaporized and the internal pressure of the closed container 14 may become extremely high.

FIG. 3 shows a cooling dehumidifier in which the closed container is a partial cooling type in order to deal with such a problem.

This cooling dehumidifier 31 includes a heat insulating cold material container 33 filled with a cold material 32 and a heat insulating case 41 installed below the cold material container 33.
The gas inflow side portion 34a and the gas outflow side portion 34b of the closed container 34 for purifying the gas are located inside the case 41 and inside the cold material container 33, respectively. The filter 39a on the gas supply side is located on the side of the case 41 having the gas inlet 42 and the outlet 43 for air or the like, and the filters 39b and 39c are the cold material container 3
It is located on side 3. In addition, the gas introduction pipe for purification 3
5 and the outlet pipe 36 are connected to the supply pipe line 3 at their ends that extend outside the device 31 through the holes in the case 41 and the heat insulating lid 37 of the cooling material container 33.

The cooling dehumidifier 31 forcibly flows air or the like from the inflow port 42 toward the outflow port 43, and the gas inflow side portion 34a of the hermetically sealed container 34.
It is possible to prevent the liquefaction of gas in the closed container 34 by providing a temperature adjusting device for heating the device and driving the temperature adjusting device as necessary.

Also, if the gas to be purified is filtered by the filters 39b, 39
Even if it is liquefied in c, it drops as a drop and falls into the filter 3
Since it vaporizes in 9a, the gas in the closed container 34 does not become a liquid.

In addition, 40 is a heater, and other configurations and operations are as follows.
There is no difference from the description of the embodiment.

FIG. 4 shows still another example of the cooling dehumidifier. This cooling dehumidifier 51 introduces a pipe line 61 into which a primary cooling material is supplied into a heat-insulating cooling material container 53 filled with a secondary cooling material 52.
In the secondary cold material 52 in the cold material container 53, the closed container 54 to which the introduction pipe 55 and the discharge pipe 56 for supplying and discharging the gas to be purified is connected is immersed. The conduit 61 and the introduction pipe 55 and the discharge pipe 56 connected to the closed container 54 extend outside the device 51 through a hole formed in the heat insulating lid 57 of the cooling material container 53, and the introduction pipe 55
The outlet pipe 56 is connected to the supply line 3. A temperature sensor 62 is installed in the cold material container 53, and the temperature sensor 62
The output of the primary cooling material supply device 64 to the pipeline 61.
It is connected to the controller 63 that controls the.

As the primary cooling material, for example, liquid nitrogen can be used, and the secondary cooling material uses a cooling material having a higher freezing point than this, for example, ethanol, and is cooled to a temperature slightly lower than the freezing point by the primary cooling material. It

Like the first embodiment, the closed container 54 is made of a material having good heat conductivity, and a plurality of filters 59a, 59b, 59c are provided with high heat conductivity with the inner wall of the container 54 in a direction substantially orthogonal to the flow direction of the purified gas. It is closely joined to maintain the sex. These filters are configured similarly to the cooling dehumidifier 11.

Reference numeral 60 in FIG. 4 is a heater, and the other configurations are the same as those of the cooling dehumidifier 11 shown in FIG.

In the cooling / dehumidifier 51, when the primary cooling material is supplied to the pipe line 61 from the primary cooling material supply control means, the cooling material container 53
The secondary cooling material 52 filled inside is cooled, and the closed container 54 is also cooled via the secondary cooling material 52.

When the temperature sensor 62 detects that the secondary cold material 52 has been cooled to a temperature slightly lower than its freezing point, the supply device 64 stops the supply of the primary cold material and the introduction pipe 55 supplies the gas to be purified. . The supplied gas flows through each filter to the outlet pipe 56 to liquefy the impurity gas (vapor) having a higher vaporization temperature than the secondary cooling material 52 (adsorption) filters 59a, 59b, 59.
The clean gas from which the impurity gas and the water are removed by the c is passed from the outlet pipe 56 through the supply pipe line 3 to the vacuum chamber 1
Is supplied to.

The secondary cooling material 52 is heated by the supply of the purified gas, but the secondary cooling material 52 cooled to a temperature slightly lower than the freezing point can be maintained at a substantially constant temperature for a relatively long time due to the latent heat of melting. it can. Therefore, the time interval for cooling the secondary cooling material 52 by the primary cooling material can be lengthened, and the temperature control thereof is easy.

Although all of these cooling dehumidifiers release the cooling material to the atmosphere, they can be circulated by collecting them in a container and liquefying them.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, FIGS. 2 to 4 are cross-sectional views of different dehumidifiers, and FIG. 5 is a diagram showing a relationship between pressure drop in a vacuum chamber and time. 1 ... vacuum chamber, 3 ... supply line, 11,31,51 ... cooling dehumidifier, 12,32,52 ... cooling material, 13,33,53 ... cooling material container,
14,34,54 ... closed container, 19a-19c, 39a-39c, 59a-59c ...
… Sintered metal filter.

Claims (1)

[Scope of utility model registration request] 1. A gas supply device for a vacuum chamber, comprising: a vacuum chamber; and a supply pipeline for supplying gas to the vacuum chamber, comprising: a heat insulating cold material container for filling the supply pipeline with a cold material. ,
A closed container made of a material having good thermal conductivity, which is immersed in a cold material in the cold material container, and an adsorption and liquefaction by cooling from a gas flowing in the closed container whose outer peripheral edge is directly fixed to the closed container. A gas supply device for a vacuum chamber, comprising a cooling dehumidifier having a plurality of stages of sintered metal filters for removing water.