JP3035879B2 - Evacuation pipe and evacuation method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vacuum exhaust pipe connected between a vacuum chamber and a vacuum pump for evacuating the vacuum chamber and a method of evacuating the vacuum chamber. The present invention relates to a vacuum evacuation pipe and a vacuum evacuation method capable of protecting an object to be processed in a vacuum chamber from contamination at a molecular level.

[0002]

2. Description of the Related Art In recent years, in the production of semiconductor LSIs, liquid crystal devices, and the like, processing of an object to be processed such as a semiconductor wafer or a glass substrate is performed under vacuum, and the object is stored or transported. 2. Description of the Related Art In the manufacture of semiconductor LSIs and the like, a high degree of cleanliness in a vacuum chamber is required due to the tendency of pattern miniaturization.

However, when the vacuum chamber is evacuated and gas analysis is performed in the vacuum chamber, NH ₃ and C ₂ H ₆ relative to the total pressure are increased as the degree of vacuum increases.
, C ₃ H ₈ , C ₄ H _10, etc., the proportion of the impurity gas increases. These gases may adhere to the surface of a semiconductor wafer, a glass substrate, or the like during film formation by a process such as vapor deposition in a vacuum atmosphere, during storage, or during transportation, and may form an organic film. When an organic film adheres to the surface of a semiconductor wafer or a glass substrate, the film formation is not successful, and a breakdown voltage failure occurs, or the formed film is easily peeled, leading to a reduction in manufacturing yield.

[0004]

If these impurity gases in the vacuum chamber can be removed, semiconductor wafers and glass substrates that are being formed, stored or transported under vacuum can be removed at the molecular level as described above. Can be protected from organic matter contamination. However, conventional filters
It is common to arrange to block the exhaust flow
And a chemical filter in the exhaust pipe
It is considered effective if placed so as to block impurity gas.
However, the conductance of the exhaust decreases and the exhaust
Difficult to flow, preventing evacuation especially at the beginning of evacuation
The problem arises.

[0005] The present invention has been made in view of the above circumstances, and has as its object to provide a vacuum exhaust pipe and a vacuum exhaust method capable of removing a trace amount of impurity gas contained in a vacuum.

[0006]

According to the present invention, a vacuum exhaust pipe is provided.
A chemical filter is attached to an exhaust pipe connected between a vacuum chamber and a vacuum pump and used to evacuate the vacuum chamber, and the chemical filter is attached to an inner peripheral surface of the vacuum exhaust pipe to reduce the conductance of the vacuum exhaust. It is characterized by having a hollow shape so as not to be scattered.

[0007] evacuation process of the present invention, at least a portion said not to reduce the conductance of evacuation to a vacuum Chang vacuum chamber or exhaust pipe for performing vacuum evacuation
A chemical filter is arranged in a hollow shape on the wall of the chamber or in the exhaust pipe, and since the conductance of the exhaust is large in the initial stage of the exhaust, it does not hinder the evacuation, and when reaching a high vacuum state, the gas molecules in the vacuum chamber are randomized. The impurity gas in the vacuum chamber is collected by being trapped by jumping into the chemical filter and jumping into the chemical filter.

[0008]

[Action] The conductance of the exhaust gas must be large in the initial stage of exhaust.
Thus, it is possible to rapidly exhaust the gas from the atmospheric pressure.
Then, in a high vacuum state, gas molecules fly randomly.
Therefore , a trace amount of impurity molecules floating in the vacuum chamber can be collected by the chemical filter. Accordingly, since the impurity gas which causes the organic substance to be contaminated at the molecular level in the vacuum chamber is removed, the object to be processed in the vacuum chamber can be protected from the molecular level contamination.

[0009]

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

FIG. 1 is an explanatory diagram of a vacuum evacuation system. In order to create a high vacuum or ultra-high vacuum space in the vacuum chamber 1, the vacuum chamber 1 is evacuated by vacuum pumps 2 and 3 through exhaust pipes 4 and 5, valves 7, and the like. At this time, it is rare that the gas is evacuated by one kind of vacuum pump.
As shown in, ^{10 -2} T vacuum chamber 1 from the atmospheric pressure
The air is exhausted up to about orr by an auxiliary pump 2 such as a roots pump. Thereafter, the turbo-molecular pump 3 is rotated while the auxiliary pump 2 is evacuating, or a gettering pump or the like is started to evacuate the vacuum chamber 1 to a high vacuum region or an ultra-high vacuum region. The exhaust pipes 4 and 5 are pipes for connecting the vacuum chamber 1 to a vacuum pump such as a turbo pump 3. A part of the vacuum exhaust pipe 4 includes one type of a filter made of ion exchange fiber, activated carbon or activated carbon fiber, or Attach a chemical filter composed of multiple combinations. Then, as the degree of vacuum in the vacuum chamber 1 increases, the ratio of ammonia (NH) to the total pressure increases.
₃ ) Collect and remove impurity gas molecules such as gas.

FIG. 2 shows an enlarged sectional view of a part of the exhaust pipe 4 according to the first embodiment of the present invention. As shown in FIG. 2, the chemical filter 6 is attached along the inner peripheral surface of the exhaust pipe 4. The chemical filter 6 is formed in a hollow shape so that the conductance of the pipe during evacuation is not reduced. The mounting position of the chemical filter 6 is considered to be almost the same degree of vacuum when the inside of the vacuum chamber 1 and the exhaust pipe 4 reach a high vacuum degree. Good. Further, the chemical filter 6 may be arranged along the wall surface in the vacuum chamber 1.

FIG. 3 shows a vacuum exhaust pipe according to a second embodiment of the present invention. A chemical filter 6 composed of an activated carbon filter, an activated carbon fiber filter, or an ion exchange fiber filter is attached to the inner peripheral surface of the exhaust pipe 4. The chemical filter 6 is coated on the inner peripheral side with a HEPA filter or a metal filter 9 for removing fine particles. When a chemical filter of activated carbon or activated carbon fiber or the like is used in which dust from the chemical filter 6 attached to the inner peripheral surface of the exhaust pipe 4 is concerned, the generated particles fly into the vacuum chamber 1. The chemical filter 6 is covered with a HEPA filter or a metal filter 9 so as to prevent particles from entering. In the present embodiment, as the chemical filter 6, an activated carbon filter, an activated carbon fiber filter, or an ion exchange fiber filter is used alone.

FIG. 4 shows a vacuum exhaust pipe according to a third embodiment of the present invention. In the present embodiment, the chemical filter is composed of a combination of two types of filters, an ion exchange fiber filter 10 and an activated carbon or activated carbon fiber filter 11. A HEPA filter or a metal filter 9 for removing fine particles is provided on the inner peripheral surfaces of the chemical filters 10 and 11 in order to prevent dust from being generated from the chemical filters 10 and 11. In addition to the combination of the activated carbon or activated carbon fiber filter 11, the ion-exchange fiber filter 10, and the activated carbon or activated carbon filter 11, the combination of the chemical filter and the ion-exchange fiber filter 10 and the activated carbon or activated carbon fiber shown in FIG. A combination of the filter 11 and the ion exchange fiber filter 10 may be used. As described above, various combinations of the activated carbon or activated carbon fiber filter 11 and the ion exchange fiber filter 10 can be considered. As compared with the case where the activated carbon or activated carbon fiber filter 11 or the ion exchange fiber filter 10 is used alone, the type of impurity gas to be removed is increased by using a combination of different types of filters in this manner, so that the impurity is more efficiently removed. Gas can be removed.

FIG. 5 shows a sectional structure of a vacuum exhaust pipe according to a fourth embodiment of the present invention. In the present embodiment, an ion exchange fiber filter 10 is used as the chemical filter 6 and H
The structure is such that a particle removal filter such as an EPA filter is omitted. When it is considered that no dust is generated from the ion exchange fiber filter, it is not necessary to provide a particle removal filter such as a HEPA filter as in this embodiment.

Next, the evacuation method of the present invention will be described. When the vacuum pumps 2 and 3 are started and the inside of the vacuum chamber 1 is evacuated, the gas is viscous at the beginning of evacuation, and the number of gas molecules from the vacuum chamber 1 to the pump 3 is larger than the number of gas molecules from the pump 3 to the vacuum chamber. It is far more than the number of gas molecules going to one side. In this state, gas molecules are transported in the gas flow direction, and almost no impurity molecules are trapped by the chemical filter 6 installed in the inner circumferential direction of the pipe.
That is, since the chemical filter 6 is hollow inside the vacuum exhaust pipe 4, the conductance of the exhaust is extremely large, and there is no problem that the chemical filter 6 arranged on the inner peripheral surface of the exhaust pipe 4 hinders the vacuum exhaust. . However, in the viscous basin, the ratio of the impurity gas to the total pressure is extremely low, and when evacuating to a high vacuum area, the time to pass through this area is between several seconds and several tens of seconds. There is no problem if it is not trapped by the filter.

When the evacuation is further continued, the gas state in the vacuum chamber 1 reaches the molecular region, and randomly flies in the vacuum space including the exhaust pipe 4. In this region, the ratio of the impurity gas to the total pressure increases. Furthermore, when the ultimate vacuum degree, which is the limit of the performance of the vacuum pump 3, is reached, the number of gas molecules traveling from the vacuum chamber 1 to the pump 3 and the number of gas molecules traveling from the pump 3 to the vacuum chamber 1 are increased. Become equal. Even in this state, the gas molecules fly randomly inside the vacuum chamber 1 and the exhaust pipe 4. When the gas molecules of the impurity gas fly around at random, the chemical filter 6 attached in the circumferential direction of the pipe naturally
The gas molecules of the impurity gas jump into the inside, where the gas molecules of the impurity gas are trapped. Then, as the time elapses, the gas molecules of the impurity gas in the gas molecules existing in the vacuum chamber 1 gradually decrease, a vacuum space with higher cleanliness is created, and the degree of vacuum also increases.

With such a mechanism, by installing the chemical filter 6 on the inner periphery of the vacuum exhaust pipe 4,
A high-quality vacuum space free of impurity gas in the vacuum space, that is, free of contamination of the object to be treated at a molecular level is created. If such a high-quality vacuum space is obtained, molecular-level contamination such as an organic film is not formed on the surface of a semiconductor wafer, a glass substrate, or the like to be formed, stored, and transported in this space, and the quality is high. Products are manufactured, which leads to improvement in manufacturing yield.

In each of the embodiments described above, the case where activated carbon, activated carbon fiber, or ion exchange fiber is used as the chemical filter has been described. However, any other filter that can adsorb impurity gas molecules in a vacuum atmosphere can be used. It does not matter what kind of chemical filter is used. Further, in the present embodiment, an example in which the chemical filter is arranged in a hollow shape in a part of the vacuum exhaust pipe has been described, but the chemical filter may be arranged in a solid shape.
In this case, the conductance of the exhaust is reduced, but a greater effect of removing impurity molecules is obtained. In addition, a chemical filter and HE
Even if a PA filter is arranged, the same trapping of impurity gas molecules as described above can be performed. Thus, various modifications can be made without departing from the spirit of the present invention.

[0019]

As described above, according to the present invention, impurity gas molecules in a vacuum chamber can be collected by a chemical filter, and a high-quality clean vacuum space can be formed. This makes it possible to improve the quality of an object to be processed, such as a semiconductor wafer or a glass substrate, on which film formation, storage, transportation, and the like are performed in a vacuum chamber, and to increase the production yield. The object to be processed is not limited to a semiconductor wafer or a glass substrate, but can be widely used in industrial fields such as food, biotechnology, and medicine.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of an evacuation system.

FIG. 2 is a sectional view showing a configuration of a vacuum exhaust pipe according to the first embodiment of the present invention.

FIG. 3 is a sectional view showing a configuration of a vacuum exhaust pipe according to a second embodiment of the present invention.

FIG. 4 is a sectional view showing a configuration of a vacuum exhaust pipe according to a third embodiment of the present invention.

FIG. 5 is a sectional view showing a configuration of a vacuum exhaust pipe according to a fourth embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vacuum chamber 3 Vacuum pump 4 Vacuum exhaust pipe 6 Chemical filter 9 HEPA filter or metal filter 10 Ion exchange fiber filter 11 Activated carbon or activated carbon fiber filter

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Hideaki Sekiguchi 11-1 Haneda Asahimachi, Ota-ku, Tokyo Ebara Corporation (56) References JP-A-63-209727 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) B01J 3/02

Claims (6)

(57) [Claims] 1. A chemical filter is attached to an exhaust pipe connected between a vacuum chamber and a vacuum pump for evacuating the vacuum chamber, wherein the chemical filter is attached to an inner peripheral surface of the vacuum exhaust pipe. A vacuum exhaust pipe having a hollow shape so as not to reduce the conductance of exhaust. 2. The vacuum exhaust pipe according to claim 1, wherein the chemical filter is covered with a filter for removing particles. 3. The chemical filter according to claim 1, wherein the chemical filter comprises one kind or a combination of a filter made of ion exchange fiber and a filter made of activated carbon or activated carbon fiber. Vacuum exhaust pipe. Wherein at least a portion wall surface of the vacuum chamber so as not to reduce the conductance of evacuation in the vacuum chamber or the exhaust pipe for performing vacuum evacuation, or the exhaust pipe
A chemical filter is arranged in a hollow shape, and since the conductance of the exhaust is large in the initial stage of evacuation, the evacuation does not hinder the evacuation, and when a high vacuum state is reached, gas molecules in the vacuum chamber fly around randomly, and the A vacuum evacuation method, wherein the impurity gas in the vacuum chamber is collected by being trapped by jumping into the vacuum chamber. 5. The vacuum evacuation method according to claim 4, wherein the chemical filter is covered with a filter for removing particles. 6. The chemical filter according to claim 4, wherein the chemical filter is formed of one or a combination of a filter made of ion exchange fiber, a filter made of activated carbon or activated carbon fiber. Vacuum evacuation method.