Title:

Apparatus for replacing gas in storage container and method for replacing gas therewith

Document Type and Number:

United States Patent 7314068

Abstract:

While gas in a general storage container with no gas inlet and in the storage container with the gas inlet is replaced in a short time, the semiconductor wafer surface is cleaned. In an apparatus for replacing gas in a semiconductor wafer storage container which includes a lid unit and a storage container main body with a gas inlet, the apparatus includes gas introducing means for introducing the gas into the storage container main body, gas evacuating means for evacuating the gas in the storage container main body, and gas circulating means for circulating the gas in the storage container main body through a chemical adsorption filter. Gas introducing means for introducing the gas from a gap between the storage container main body and the lid unit while the lid unit is opened in the storage container mounting means is provided in the storage container with no gas inlet.

Inventors:

Nakano, Ryuichi (Shisui-machi, JP)
Hyobu, Yukihiro (Tokyo, JP)
Okamoto, Yoshihisa (Tokyo, JP)

Plaque It!

CROSS-REFERENCE TO RELATED APPLICATION

This application claims, under 35 USC 119, priority of Japanese Application No. 2004-142727 filed May 12, 2004, and Japanese Application No. 2004-153025 filed May 24, 2004.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an apparatus for replacing gas in a storage container and a method for replacing gas therewith. The apparatus for replacing gas in a storage container replaces gas in a storage container with an inert gas and the like while accommodating a material such as semiconductor wafers for which prevention of foreign matter adhesion is required, and the apparatus for replacing gas in a storage container also cleans surfaces of the semiconductor wafers and the like accommodated in the storage container.

2. Description of the Related Art

While a diameter of the semiconductor wafer is increased, miniaturization of a process pattern formed in the semiconductor wafer is rapidly in progress. Therefore, in the semiconductor wafer, technical requirements for the prevention of contamination and the cleanness of the surface are increased more and more.

In order to respond to such requirements, in the semiconductor wafer storage container for accommodating and storing a semiconductor wafer, there is developed the technology in which surface degradation caused by adsorption of impurity elements or moisture in the storage container is prevented while the semiconductor wafer surfaces are kept clean.

Recently, the semiconductor wafer storage container has a structure in which a lid of the storage container can mechanically be opened and closed so that the semiconductor wafers are automatically loaded and unloaded in an unmanned process room having a high cleanness level.

Further, use of the semiconductor wafer storage container, in which corrosion of the electrodes formed in the semiconductor wafer surface can be prevented by filling the inside of the storage container with the inert gas, is also becoming widespread. For example, Japanese Patent Application Laid-Open (JP-A) No. 5-74921 (pp 4 to 5, FIG. 2) discloses the technology concerning gas replacement in the storage container. In the gas replacement disclosed in JP-A No. 5-74921, an airtight maintaining type coupler which can be connected to a gas setting device is mounted on the semiconductor wafer storage container, and the storage container is filled with the dry and clean gas such as air, a nitrogen gas, and the inert gas through the airtight maintaining type coupler.

However, in the conventional gas replacing apparatus and method disclosed in JP-A No. 5-74921, because the gas replacement is performed after the air in the storage container is evacuated, it is necessary that ultimate vacuum in the storage container becomes sufficiently high after the evacuation in order to increase gas purity after the gas replacement. Therefore, the plastic storage container usually used has a problem of pressure-resistance intensity.

When the vacuum of the storage container is reduced before the gas replacement, in order to perform the high-purity gas replacement in an airtight manner, there is the problem that a sufficiently long time is required for the gas replacement.

In order to remove the moisture and impurities adsorbed onto the semiconductor wafer, it is necessary that the inside of the storage container is heated with a heating device provided in the storage container. Therefore, there are problems that the plastic storage container cannot be used and a treatment-time is lengthened.

In the conventional gas replacing apparatus and method disclosed in JP-A No. 5-74921, it is necessary to use the semiconductor wafer storage container in which a replacement gas inlet is made. Therefore, for the generally used semiconductor wafer storage container with no replacement gas inlet, there is the problem that the gas replacement cannot be performed.

SUMMARY OF THE INVENTION

An apparatus for replacing gas in a storage container of the invention is an apparatus for replacing gas in a storage container which includes a storage container main body having a gas inlet and a lid unit blocking the storage container main body, the apparatus including gas introducing means for introducing the gas into the storage container main body; gas evacuating means for evacuating the gas in the storage container main body; and gas circulating means for circulating the gas in the storage container main body through a chemical adsorption filter. The apparatus for replacing gas in a storage container of the invention enables the high-purity gas replacement in a short time by simultaneously performing the gas evacuation and introduction in the storage container.

Further, in an apparatus for replacing gas in a storage container of the invention, the lid unit of the storage container is mounted on the storage container main body in an airtight manner to communicate with a gas replacing passage while accommodated inside the apparatus for replacing gas in a storage container, the gas inside the storage container is replaced from a gap between the lid unit and the storage container main body by demounting the lid unit while the airtight state is kept. Gas introducing means is used as means for replacing the gas in the storage container from the gap between the lid unit and the storage container main body. The gas introducing means is configured to include a gas introducing nozzle which is inserted into the storage container main body from the gap between the storage container main body and the lid unit to introduce the gas into the storage container main body.

In the apparatus for replacing gas in a storage container and the gas replacing method therewith of the invention, atmosphere in the storage container can efficiently be replace with a target gas in a short time, and the surfaces of the semiconductor wafer and the like can be cleaned by circulating the replacement gas. Therefore, the process for forming the semiconductor wafer suitable for the high integration can be realized. Since the automation of the gas replacement can be achieved, the apparatus and method of the invention can be compatible with the automated load/unload system, and the contamination in the process room can be suppressed to the minimum.

Further, the already-existing semiconductor wafer storage container can be used in an as-is state, and no additional forming is required. Therefore, the invention is the extremely useful gas replacing apparatus and method which can generally be used.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing a basic configuration of a gas replacing apparatus according to the invention;

FIG. 2 is a block diagram showing a basic configuration of the gas replacing apparatus according to the invention;

FIG. 3 is a block diagram showing a basic configuration of the gas replacing apparatus according to the invention;

FIG. 4 a is a sectional view showing the partial configuration of the gas replacing apparatus when a lid unit is closed, and FIG. 4 b is a sectional view showing the partial configuration of the gas replacing apparatus when the lid unit is opened;

FIG. 5 is a sectional view showing a partial configuration of the gas replacing apparatus according to the invention;

FIG. 6 is a sectional view showing a configuration of the gas replacing apparatus according to the invention and a circulated gas flow;

FIG. 7 is a sectional view showing the configuration of the gas replacing apparatus according to the invention and the circulated gas flow;

FIG. 8 is a flowchart showing steps of a gas replacing method according to the invention;

FIG. 9 is a flowchart showing steps of a gas replacing method according to the invention;

FIG. 10 a is a partial sectional view of a lid latching structure of the gas replacing apparatus showing a configuration of an insertion of a detachment moving mechanism, and FIG. 10 b is a partial sectional view of a lid latching structure of the gas replacing apparatus showing action of the lid latching structure;

FIG. 11 is a block diagram showing a basic configuration of a gas replacing apparatus according to a second embodiment of the invention;

FIG. 12 is a block diagram showing a basic configuration of a gas replacing apparatus according to a third embodiment of the invention;

FIG. 13 is a block diagram showing a basic configuration of a gas replacing apparatus according to a fourth embodiment of the invention;

FIG. 14 is a sectional view showing a basic configuration of a gas replacing apparatus according to a fifth embodiment of the invention;

FIG. 15 a is a partial sectional view showing a basic configuration of a gas replacing apparatus according to a sixth embodiment of the invention and showing the state in which the semiconductor wafer storage container is mounted on a moving stage; FIG. 15 b is a partial sectional view showing a basic configuration of a gas replacing apparatus according to a sixth embodiment of the invention and showing the moving stage moved on the base in the direction shown by the arrow to cause the storage container main body to come into close contact with an airtight maintaining seal provided in the dust collecting wall; and FIG. 15 c is a partial sectional view showing a basic configuration of a gas replacing apparatus according to a sixth embodiment of the invention and showing the storage container main body mounting means closed to fix the storage container main body to the dust collecting wall;

FIG. 16 a is a partial sectional view showing a partial configuration of the gas replacing apparatus according to the invention, as shown in FIG. 15 c , viewed from the direction in parallel with the semiconductor wafer; FIG. 16 b is a partial sectional view of the gas replacing apparatus according to the invention showing the lid unit rotated by the detaching control means moving the detachment moving mechanism in the direction shown by the arrow to connect the leading end of the lid unit latching structure detaching mechanism to the lid unit holding mechanism; FIG. 16 c is a partial sectional view of the gas replacing apparatus according to the invention showing when the lid unit detaching control means rotates the lid unit latching structure detaching mechanism, the lid unit latching structure is removed from the connection hole thereby separating the storage container main body from lid unit; and FIG. 16 d is a partial sectional view of the gas replacing apparatus according to the invention showing the lid unit detaching control means moving the detachment moving mechanism in parallel in the direction of the arrow;

FIG. 17 is a partial sectional view showing a configuration of the gas replacing apparatus according to the invention;

FIG. 18 a is a partial sectional view showing a lid latching structure of the gas replacing apparatus according to the invention; and FIG. 18 b showing the detaching mechanism of FIG. 18 a rotated in the direction of the arrow;

FIG. 19 a is a partial sectional view of a sixth embodiment of the invention showing a gas introducing nozzle before insertion; and FIG. 19 b is a partial sectional view showing the gas introducing nozzle after insertion;

FIG. 20 a is a partial sectional view of a seventh embodiment of the invention showing a gas introducing nozzle before insertion; FIG. 20 b is a partial sectional view of the seventh embodiment of the invention showing the gas introducing nozzle in the middle of insertion; and FIG. 20 c is a partial sectional view of the seventh embodiment of the invention showing the gas introducing nozzle after insertion;

FIG. 21 a is a partial sectional view of a modification of the seventh embodiment wherein sub-nozzles are arranged in gaps between semiconductor wafers; and FIG. 21 b is a partial sectional view of a modification of the seventh embodiment wherein sub-nozzles are arranged above and in alignment with each of the semiconductor wafers;

FIG. 22 is a flowchart showing steps of a gas replacing method according to the invention; and

FIG. 23 is a flowchart showing steps of a gas replacing method according to the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the accompanying drawings, preferred embodiments of the invention will be described.

First Embodiment

A first embodiment of the invention will be described using the drawings. In the first embodiment, the semiconductor wafer storage container in which the semiconductor wafers are stored will be described by way of illustration as the storage container in which the inside is necessary to keep clean. The invention is not limited to the semiconductor wafer, but the invention can be also applied to the storage container for precision parts such as ICs for which a storage space is necessary to keep clean.

FIG. 1 is a block diagram showing a basic configuration of a gas replacing apparatus for a semiconductor wafer storage container according to the invention. A semiconductor wafer storage container 1 includes a storage container main body 2 and a lid unit 3 . The semiconductor wafer storage container 1 has a sealed structure with a seal so that moisture and dust in atmosphere are prevented from intruding into the container. In the sealed semiconductor wafer storage container 1 , the semiconductor wafers are stored while separated from one another with predetermined intervals.

In the semiconductor wafer storage container 1 shown in FIG. 1, a replacement gas inlet is provided in the storage container main body 2 , and a replacement gas outlet is provided in the lid unit 3 . A circulated gas inlet and a circulated gas outlet are provided in the storage container main body 2 . It is also possible that both the replacement gas inlet and the replacement gas outlet are provided in the storage container main body 2 , or it is also possible that both the replacement gas inlet and the replacement gas outlet are provided in the lid unit 3 . It is also possible that both the circulated gas inlet and the circulated gas outlet are provided in the lid unit 3 .

A gas evacuating means 4 and the replacement gas outlet are coupled to each other with a gas evacuation pipe. The gas evacuating means 4 can evacuate air or gas in the semiconductor wafer storage container 1 .

Gas introducing means 5 and the replacement gas inlet are coupled to each other with a gas introducing pipe. The gas introducing means 5 can introduce the gas into the semiconductor wafer storage container 1 .

The circulated gas inlet and the circulated gas outlet are coupled to gas circulating means 6 through a circulated gas pipe to constitute a gas circulating passage. A chemical adsorption filter 7 is inserted into the gas circulating passage. The chemical adsorption filter 7 has a function of adsorbing and filtering an impurity gas component included in circulated gas. In the chemical adsorption filter 7 , the moisture and impurities in the gas are removed by passing the gas through a chemical adsorbent encapsulated in a stainless-steel vessel. Well-known examples of the chemical adsorbent include metal meshes made of stainless steel or nickel whose surface is activated, porous glass fiber, and ceramic materials such as porous alumina.

The method for replacing the gas with the gas replacing apparatus shown in FIG. 1 will be described below.

In a first step, the semiconductor wafer storage container 1 is connected to the gas evacuating means 4 , the gas introducing means 5 , and the gas circulating means 6 . In a second step, the gas evacuating means 4 is operated to start the evacuation of the air in the semiconductor wafer storage container 1 . In a third step, the gas is introduced from the gas introducing means 5 into the semiconductor wafer storage container 1 while evacuated by the gas evacuating means 4 .

A high-purity dry nitrogen gas is used as the gas used in the third step. According to a processing status of the semiconductor wafer in the container, sometimes dry argon gas is used. Further, for the purpose of cost reduction, sometimes the gas in which dry air is mixed with the high-purity dry nitrogen gas is used. In this case, it is desirable that at least 95% nitrogen gas is contained in the mixture gas.

At the time when the third step is started, it is not necessary that the inside of the semiconductor wafer storage container 1 is evacuated in high vacuum, but is sufficient that the semiconductor wafer storage container 1 is evacuated in a reduced-pressure state. The many conventional gas replacing apparatuses have closed-system structures in which one port is used for both the gas inlet and the gas outlet. In the conventional gas replacing apparatus, when the gas remains in the semiconductor wafer storage container 1 before the third step, because the residual gas affects the replacement gas purity, it takes at least 30 to 60 minutes to replace the gas. On the contrary, the gas replacing apparatus according to the invention has an open-system structure, so that the gas in the semiconductor wafer storage container 1 is efficiently replaced by performing the gas introduction and the gas evacuation at the same time.

After the gas introduction and the gas evacuation are performed for a given time in the third step, the gas introduction from the gas introducing means 5 to the semiconductor wafer storage container 1 and the gas evacuation from the semiconductor wafer storage container 1 by the gas evacuating means 4 are stopped in a fourth step. The time necessary for the third step depends on a volume of the semiconductor wafer storage container 1 or the processing status of the semiconductor wafer. Typically, when the semiconductor wafer storage container 1 has the volume of about 60 liters, it takes at least about 10 to 30 minutes to perform the third step.

Then, in a fifth step, the gas in the semiconductor wafer storage container 1 is circulated with the gas circulating means 6 . At this point, the circulated gas has the function of removing the impurities and functional groups on the surface of the semiconductor wafer. The chemical adsorption filter 7 adsorbs the moisture and impurities to clean the circulated gas. It takes about 5 to 30 minutes to circulate the gas.

When the high-purity dry nitrogen gas having the purity in the range of about 99.5% to about 99.999% is used as the gas introduced in the third step, the moisture and impurity adsorbed on the semiconductor wafer surface can be efficiently removed in the fifth step.

In the gas introduced in the third step, a not more than about 5% reactive gas is mixed with the high-purity dry nitrogen gas not lower than 99% in purity. The reactive gas includes an ozone gas, a hydrogen gas, or an ammonia gas having the purity not lower than 99%, or the reactive gas includes a mixture gas of the above-described gases. Therefore, in the fifth step, the effect of removing the moisture and impurities adsorbed on the semiconductor wafer surface is enhanced, and the surface cleaning effect is obtained in about 5 to 10 minutes.

Thus, in the case where the dry nitrogen gas with which the reactive gas is mixed is used in the third step, in order to prevent the reactive gas from remaining in the semiconductor wafer storage container 1 , the steps from the third step to the fifth step are repeated using the high-purity dry nitrogen gas in which the reactive gas is not included.

After the fifth step, in a sixth step, the replacement gas inlet, the replacement gas outlet is, the circulated gas inlet, and the circulated gas outlet are closed in the semiconductor wafer storage container 1 . Then, the gas evacuating means 4 , the gas introducing means 5 , and the gas circulating means 6 are detached from the semiconductor wafer storage container 1 to end the gas replacing method.

FIG. 2 shows another mode of the gas replacing apparatus according to the invention. In FIG. 2, the same element as for FIG. 1 is indicated by the same numeral. In the semiconductor wafer storage container 1 of FIG. 2, the lid unit 3 is mounted so as to be entirely accommodated in the gas circulating passage of semiconductor wafer storage container attaching means 8 . The semiconductor wafer storage container attaching means 8 attaches the semiconductor wafer storage container 1 in the storage container main body 2 while the storage container main body 2 is sealed. A seal for keeping airtight is arranged in a mating surface between the storage container main body 2 and the semiconductor wafer storage container attaching means 8 , and the seal is attached by mechanically pressing the storage container main body 2 and the semiconductor wafer storage container attaching means 8 .

The semiconductor wafer storage container attaching means 8 has a space in which the lid unit 3 can freely be opened and closed while the semiconductor wafer storage container attaching means 8 is connected to the storage container main body 2 . The space constitutes a part of the gas flow passage sealed from the environment.

The storage container main body 2 and the lid unit 3 are coupled to each other by a lid unit latching structure. The storage container main body 2 and the lid unit 3 can be separated from each other by manually or mechanically releasing the lid unit latching structure.

In FIG. 2, the replacement gas inlet is provided in the storage container main body 2 , and the replacement gas inlet is coupled to the gas introducing means 5 . The replacement gas outlet is provided in the semiconductor wafer storage container attaching means 8 , and the replacement gas outlet is coupled to the gas evacuating means 4 . The circulated gas inlet is coupled to the replacement gas inlet provided in the storage container main body 2 , and the circulated gas outlet is provided in the semiconductor wafer storage container attaching means 8 . The circulated gas inlet and the circulated gas outlet are connected to the gas circulating means 6 to form the gas circulating passage. In the gas circulating passage, the chemical adsorption filter 7 described in FIG. 1 is attached.

The method for replacing the gas in the semiconductor wafer storage container with the gas replacing apparatus shown in FIG. 2 will be described below. The gas replacing method differs from the method for replacing the gas with the gas replacing apparatus shown in FIG. 1 in that the semiconductor wafer storage container 1 is attached to the semiconductor wafer storage container attaching means 8 in a first step.

In a second step, the semiconductor wafer storage container 1 is connected to the gas introducing means 5 . The gas evacuating means 4 is previously attached to the semiconductor wafer storage container attaching means 8 , and the gas circulating means 6 is previously attached to the semiconductor wafer storage container attaching means 8 and the gas introducing means 5 , so that it is not necessary that the gas evacuating means 4 and the gas circulating means 6 are newly attached.

In a third step, the lid unit 3 is detached from the storage container main body in the gas passage of the semiconductor wafer storage container attaching means 8 . Namely, the lid unit latching structure connecting the storage container main body 2 and the lid unit 3 is manually or mechanically released, which allows the storage container main body 2 and the lid unit 3 to be separated from each other. In the case where the lid unit latching structure is manually released, because the semiconductor wafer storage container attaching means 8 has a function of a glove box, the semiconductor wafer storage container attaching means 8 can perform not only the release of the lid unit latching structure but the separation between the storage container main body 2 and the lid unit 3 without breaking the airtight of the gas passage.

Because gas replacement post-steps are similar to the steps from the second step to the fifth step described in FIG. 1, the description of the gas replacement post-steps is omitted. In a sixth step, inside the semiconductor wafer storage container attaching means 8 , the storage container main body 2 and the lid unit 3 are manually or mechanically caused to come into close contact with each other without breaking the airtight of the gas passage, and the storage container main body 2 and the lid unit 3 are connected to each other by locking the lid unit latching structure.

In a seventh step, after the replacement gas inlet of the storage container main body 2 is sealed, the gas introducing means 5 is detached from storage container main body 2 , and the semiconductor wafer storage container 1 is detached from the semiconductor wafer storage container attaching means 8 to end the gas replacing step.

FIG. 3 shows another mode of the apparatus for replacing the gas in the semiconductor wafer storage container according to the invention. The mode shown in FIG. 3 has lid unit detaching means 12 and lid unit detaching control means 13 . The lid unit detaching means 12 mechanically detaches the lid unit 3 from the storage container main body 2 of the semiconductor wafer storage container 1 , and the lid unit detaching control means 13 controls the lid unit detaching means 12 .

The storage container main body 2 and the lid unit 3 are fixed to each other by the lid unit attaching structure. The lid unit latching structure can mechanically be detached from the outside so that the semiconductor wafers stored in the semiconductor wafer storage container 1 can automatically be loaded to and unloaded from a processing chamber.

FIGS. 10A and 10B show examples of a configuration of the lid unit latching structure. As shown in FIG. 10A, the lid unit latching structure includes a slide structure 183 , a disc structure 181 , and a guide structure 178 . The slide structure 183 is moved in parallel and inserted into a connection hole made in the storage container main body 2 . The rotatable disc structure 181 has a lid unit detaching means mounting structure 180 in the rotating center while a pin 182 is formed in an outer periphery. The guide structure 178 guides the movement of the slide structure. The guide structure 178 also acts as a presser of the disc structure 131 . The slide structure 183 is fitted into the pin 182 provided in the outer periphery of the disc structure through a rotatable hole 184 . A rectangular mounting unit 175 is formed at a leading end of a lid unit latching structure detaching mechanism 173 . The mounting unit 175 is inserted into a rectangular hole made in the lid unit detaching means mounting structure 180 through a rectangular hole made in a guide structure 179 .

After the mounting unit 175 is inserted into the lid unit detaching means mounting structure 180 , when the lid unit latching structure detaching mechanism 173 is rotated in a direction shown by an arrow 185 of FIG. 10B, the disc structure 181 is rotated. The pin 182 inserted into the hole 184 is simultaneously rotated according to the rotation of the disc structure 181 , and the slide structure 183 is moved in parallel in the direction shown by a narrow 186 . As a result, the leading end of the slide structure 183 is inserted into the connection hole to connect the storage container main body and the lid unit. When the storage container main body and the lid unit are separated, the lid unit latching structure detaching mechanism 173 is rotated in the reverse direction. As the lid unit latching structure detaching mechanism 173 is rotated, the mounting unit 175 located at the leading end of the lid unit latching structure detaching mechanism 173 is supported between a lid unit supporting mechanism 180 and the guide structure 178 , and the lid unit detaching mechanism 173 and the lid unit are connected and held. The lid unit detaching control means controls the lid unit detaching means.

On the other hand, the semiconductor wafer storage container attaching means 8 includes storage container main body mounting means 9 and dust collecting means 10 . The dust collecting means 10 includes a dust collecting chamber. The dust collecting chamber is surrounded by dust collecting walls, and the dust collecting chamber becomes the space in which the lid unit 3 is entirely accommodated. The storage container main body 2 is closely mounted to the dust collecting wall through the airtight maintaining seal. The storage container main body mounting body 9 fixes the storage container main body 2 in an airtight manner by pressing the storage container main body 2 against the dust collecting wall with a spring structure.

The lid unit detaching means 12 has a mechanism detaching the lid unit 3 in the dust collecting means 10 . The lid unit latching structure provided in the lid unit 3 is mechanically detached by the lid unit detaching mechanism.

As with the mode shown in FIG. 2, in the apparatus for replacing gas in a semiconductor wafer storage container shown in FIG. 3, the gas evacuating means 4 is coupled to the dust collecting means 10 , and the gas introducing means 5 is coupled to the storage container main body 2 . The gas circulating means 6 is coupled to the dust collecting means 10 and the gas introducing means 5 , and the gas circulating means 6 circulates the gas in the semiconductor wafer storage container 1 through the gas circulating means 6 .

The gas evacuating means 4 includes a dust collecting filter 14 , an evacuation pump 15 , a third valve 19 , a fourth valve 20 , and a fifth valve 21 . These elements are connected by the gas pipes constituting the gas passage. A usual oil-sealed rotary vacuum pump can be used as the evacuation pump 15 . In the case of the use of the oil-sealed rotary vacuum pump, the exhaust is discharged from the oil-sealed rotary vacuum pump through a sealed exhaust duct so that a clean room is not contaminated by oil mist. Like the chemical adsorption filter, the dust collecting filter 14 removes the micro-dust included in the evacuation gas by filtering and adsorbing the micro-dust with the filter having the sub-micron mesh or porous structure. However, unlike the chemical adsorption filter, the adsorption activity for the moisture and impurities is not required for the dust collecting filter 14 .

The third valve 19 , the fourth valve 20 , and the fifth valve 21 switching a connection pattern of the gas passage by opening and closing these valves. The fourth valve 20 is closed and the fifth valve 21 is opened, which allows the gas passage to be coupled between the gas evacuating means 4 and the dust collecting means 10 . The evacuation pump 15 is operated while the third valve 19 and the fifth valve 21 are closed, which allows the air to be removed in the gas passage between the fifth valve 21 and the evacuation pump 15 . Then, when the fifth valve 21 is opened, the air is prevented from entraining into the gas evacuating means 4 . In the case where the evacuation pump is stopped, the fifth valve 21 is closed, the third valve 19 is opened to return the gas passage immediately in front of the evacuation pump 15 to atmospheric pressure, and then the evacuation pump 15 is stopped. Therefore, the evacuation pump 15 can be stopped without causing the oil and dust in the evacuation pump 15 to reversely flow into the gas passage to contaminate the gas passage.

The gas introducing means 5 includes the first valve 17 , the second valve 18 , and the gas pipe. The gas introducing means 5 is connected to gas supply means 11 . Examples of the gas supply means 11 include a compressed gas cylinder and a gas supply pipe provided in the clean room. When the first valve 17 and the second valve 18 are opened, the gas passage is connected between the gas supply means 11 and the storage container main body 2 . In the case where a plurality of kinds of gas are supplied to the gas introducing means 5 , the gas supply means 11 is configured by the plurality of compressed gas cylinders or the plurality of gas supply pipes.

The gas circulating means 6 includes a circulating pump 16 , the chemical adsorption filter 7 , the dust collecting filter 14 , the second valve 18 , and the fourth valve 20 . These elements are connected by the gas pipes constituting the gas passage. In the embodiment shown in FIG. 3, the gas circulating means 6 is connected to the gas evacuating means 4 and the gas introducing means 5 . The dust collecting filter 14 , the second valve 18 , and the fourth valve 20 are shared among the gas circulating means 6 , the gas evacuating means 4 , and the gas introducing means 5 . The first valve 17 and the fifth valve 21 are closed and the fourth valve 20 is opened, which allows the gas circulating passage to be formed for the storage container main body 2 and the dust collecting means 10 . Namely, the fourth valve 20 and the fifth valve 21 form gas flow switching means 22 such that the fourth valve 20 and the fifth valve 21 is opened and closed to switch the gas flows of the evacuating means and the gas circulating means.

FIG. 4 is a sectional view showing a detail configuration near the dust collecting means with respect to the semiconductor wafer gas circulating apparatus shown in FIG. 3. FIGS. 4A and 4B are partial sectional views showing a state in which the storage container main body and the lid unit are connected by the lid unit latching structure. The semiconductor wafer storage container is formed by a storage container main body 101 and a lid unit 102 . The semiconductor wafer storage container is attached while sealed with an airtight maintaining seal 103 . The semiconductor wafers 100 are stored in the semiconductor wafer storage container. Usually an elastic structure referred to as O-ring is used as the airtight maintaining seal 103 . The elastic structure is made of rubber resins or silicone resins.

The lid unit latching structure is provided in the lid unit 102 . The lid unit latching structure is formed by a slide structure 108 and a disc structure 109 . A lid unit holding mechanism 110 is provided in the rotating center of a disc structure 109 . As described above, the slide structure 108 is mounted in the pin provided in the outer periphery of the disc structure 109 through the rotatable hole, and the slide structure 108 is moved in parallel according to the rotation of the disc structure 109 . The lid unit holding mechanism 110 provided near the rotating center of the disc structure 109 has a hole or groove structure into which the rectangle is inserted. The lid unit 102 can be held by inserting the rectangular structure formed at the leading end of a lid unit latching structure latching mechanism 114 into the lid unit holding mechanism 110 . An end portion of the slide structure 108 connects the storage container main body 101 and the lid unit 102 by inserting the end portion of the slide structure 108 into a connection hole 101 A made in the storage container main body 101 .

The lid unit detaching mechanism includes a gas passage forming mechanism 111 , a lid unit latching structure detaching mechanism 114 , and a detachment moving mechanism 111 . In the example shown in FIG. 4, the gas passage forming mechanism 111 and the detachment moving mechanism 112 are integrally formed, and the lid unit latching structure detaching mechanism 114 is rotatably mounted in the gas passage forming mechanism 111 and the detachment moving mechanism 112 . The detachment moving mechanism 112 can be moved in parallel in a dust collecting chamber 107 through a port made in a dust collecting wall 104 . Because an airtight maintaining seal 115 is mounted in the port, even if the detachment moving mechanism 112 is moved, the gas in the dust collecting room 107 never leaks to the outside.

The dust collecting wall 104 and the storage container main body 101 are closely mounted by the storage container main body mounting means 106 . At this point, the airtight maintaining seal 105 plays a role preventing the leakage of the gas from the mounting portion.

When the storage container main body 101 is mounted on the dust collecting wall 104 , the lid unit detaching mechanism is moved and brought close to the lid unit 102 , and the rectangular leading end of the lid unit latching structure detaching mechanism 114 is inserted into the lid unit holding mechanism 110 and stopped. At this point, predetermined gaps are formed between the gas passage forming mechanism 111 and the lid unit 102 . The gap is formed, such that the gap is broad in a circumferential portion of the gas passage forming mechanism 111 and the gap is narrow in other portions. The gap formed in the circumferential portion of the gas passage forming mechanism 111 is referred to as a pump chamber 116 , and the gap formed in other portions is referred to as airflow gap 117 . Specifically the gap of the pump chamber 116 ranges from about 10 to about 20 mm, the gap of the other portions is not more than about 1 mm. These gaps may be formed so that the volume of the pump chamber 116 is sufficiently larger than that of the gap spaces of other portions.

On the other hand, a communication hole 113 is formed near the center of the gas passage forming mechanism 111 . The communication hole 113 is communicated with the airflow gap 117 and the dust collecting chamber 107 . A diameter of the communication hole 113 is formed so as to be gradually increased from the side of the airflow gap 117 toward the side of the dust collecting chamber 107 . Although only one communication hole 113 is shown in FIG. 4, it is also possible that the plurality of communication holes 113 are made.

FIG. 4B is a partial sectional view showing the state in which the storage container main body and the lid unit are separated from each other.

When the lid unit latching structure detaching mechanism 114 inserted into the lid unit holding mechanism 110 is rotated as shown by a narrow 118 , the disc structure 109 is also rotated, and the slide structure 108 mounted to the pin provided in the outer periphery of the disc structure 109 through the rotatable hole is moved in parallel, which allows the slide structure 108 is extracted from the connection hole 101 A as shown in FIG. 4B. Therefore, the storage container main body 101 and the lid unit 102 are separated from each other.

Then, the detachment moving mechanism 112 moves the lid unit 102 , the lid unit latching structure detaching structure 114 , and the gas passage forming mechanism 111 in parallel in the direction of an arrow 119 in a collective manner, which allows the seal to be broken between the storage container main body 101 and the lid unit 102 to form the gap between the storage container main body 101 and the lid unit 102 . The gap forms the gas passage during the gas replacement or gas circulation.

As can be seen from FIG. 4B, even if the lid unit 102 is moved, the gaps of the pump chamber 116 and the airflow gap 117 are never changed.

FIG. 5 schematically shows a partial sectional view of another mode of the apparatus for replacing gas in a semiconductor wafer storage container according to the invention. In the mode shown in FIG. 5, one rotating and moving shaft functions as both the lid unit latching structure detaching mechanism and the detachment moving mechanism. The lid unit latching structure detaching mechanism and the detachment moving mechanism constitutes a part of the lid unit detaching mechanism. Therefore, the structure of the lid unit detaching mechanism can remarkably be simplified. The rotating and moving shaft is mounted in bearings 120 and 121 . It is possible that general ball bearing is used as the bearings 120 and 121 . However, sometimes the dust and the oil mist might be generated to contaminate the gas passage. Therefore, it is preferable that a fluorine-contained polymer bearing is used as the bearings 120 and 121 . The fluorine-contained polymer bearing has good slide properties, and the dust and the oil mist are never generated in the fluorine-contained polymer bearing. Teflon (product name from DuPont) is well known as the specific material.

The bearing 120 is mounted in the gas passage forming mechanism 111 to connect the rotating and moving shaft, and an anti-disconnection latch 122 is formed in order to prevent the disconnection of the rotating and moving shaft. The bearing 121 is mounted in the dust collecting wall 104 to connect the rotating and moving shaft. The bearing 121 also supports the rotating and moving shaft so that the rotating and moving shaft can be moved in parallel. By providing at least two rotating and moving shafts in the gas passage forming mechanism 111 , only the rotating and moving shaft can be rotated as shown by the arrow 118 while the gas passage forming mechanism 111 is not rotated. Further, the rotating and moving shaft and the gas passage forming mechanism 111 can be moved in the dust collecting chamber 107 by moving the rotating and moving shaft in the direction of an arrow 119 .

The gas replacing method in which the apparatus for replacing gas in a semiconductor wafer storage container of the invention is used will be described below. FIG. 8 is a flowchart showing the method for replacing the gas in the semiconductor wafer storage container of the invention shown in FIG. 3. The steps for replacing the gas in the semiconductor wafer storage container will be described referring to FIGS. 3, 6 , 7 , and 8 .

In a container mounting step 201 , while the lid unit is caused to enter the dust collecting chamber, the semiconductor wafer storage container is mounted on the semiconductor wafer storage container mounting means in an airtight manner. At this point, as shown in FIG. 6, the storage container main body 101 and the lid unit 10 are sealed with the airtight maintaining seal 103 . Usually twenty-five semiconductor wafers 100 are stored in the storage container while arranged in parallel. In the container mounting step 201 , the storage container main body 101 is closely fixed by using the storage container main body mounting means 106 to mechanically press the storage container main body 101 against the airtight maintaining seal 105 provided in the dust collecting wall 104 .

Then, in a gas introducing means connecting step 202 , the replacement gas inlet and the gas introducing means of the storage container main body are connected. In FIG. 6, the gas introducing means is connected to a replacement gas inlet 126 provided in the storage container main body 101 . The gas introducing means includes a first valve 131 , a second valve 132 , and a gas introducing pipe 137 . An airtight maintaining type coupler 125 connects the gas introducing means and a replacement gas inlet 126 provided in the storage container main body 101 . The airtight maintaining type coupler 125 includes a male die and a female die. The male die of the airtight maintaining type coupler is previously mounted on the replacement gas inlet 126 , and the female die is mounted on the gas introducing means. Accordingly, the connection between the storage container main body 101 and the gas introducing means only by inserting the male die into the female die. The male die of the airtight maintaining type coupler keeps the airtight of the semiconductor wafer storage container before the insertion, and the gas passage is formed between the storage container main body 101 and the gas introducing means by the insertion.

In a lid unit holding step 203 , both the gas passage forming mechanism and the lid unit latching structure detaching mechanism are moved and brought close to the lid unit, and the lid unit is connected and held by the lid unit holding mechanism. Specifically, in FIG. 6, both the gas passage forming mechanism 111 and the lid unit latching structure detaching mechanism 114 are moved and brought close to the lid unit 102 by the detachment moving mechanism 112 , and the leading end of the lid unit latching structure detaching mechanism 114 is inserted into the lid unit holding mechanism 110 to hold the lid unit. The lid unit latching structure detaching mechanism 114 is driven by transmission of force from a drive source such as a motor in a detaching drive mechanism 140 provided outside the dust collecting wall 104 . The drive source in the detaching drive mechanism 140 is controlled by a control circuit in a detaching-drive control mechanism 141 .

Then, in a lid unit demounting step 204 , the lid unit latching structure which connects the storage container main body and the lid unit is operated by the lid unit latching structure detaching mechanism, and the storage container main body and the lid unit are separated. Specifically, in FIG. 6, the lid unit latching structure detaching mechanism 114 is rotated by the detaching drive mechanism 140 to demount the lid unit latching structure, and the detachment moving mechanism 112 is moved by using the detaching drive mechanism 140 again, which allows the storage container main body 101 and the lid unit 102 to be separated by simultaneously moving the lid unit latching structure detaching mechanism 114 , the gas passage forming mechanism 111 , and the lid unit 102 supported by the lid unit holding mechanism 110 . The gap is formed between the airtight maintaining seal 103 and the lid unit 102 by the separation of the storage container main body 101 and the lid unit 102 , which allows the gas passage to connect between the storage container main body 101 and the dust collecting chamber 107 .

In a reduced pressure step 205 , the evacuating means evacuates the dust collecting chamber to reduce the pressure. Specifically, in FIG. 6, a fifth valve 135 and a third valve 133 are closed, and an evacuation pump 127 performs degassing in an evacuating pipe 138 . At this point, a fourth valve 134 is closed. Then, the fifth valve 135 is opened to evacuate the air in the dust collecting chamber 107 . At this point, because the storage container main body 101 and the lid unit 102 are separated, the air in the storage container main body 101 is also evacuated at the same time.

In a gas replacing step 206 , while the evacuating means evacuates the dust collecting chamber, the gas is introduced to the storage container main body from the replacement gas inlet of the storage container main body using the gas introducing means. The gas replacing step 206 will specifically be described referring to FIG. 6. The gas introducing means is connected to the gas supply means which includes a gas supply source 123 , a reduced-pressure valve 124 , and a gas supply pipe 136 . The compressed gas cylinder or gas piping in the clean room, which is of the gas supply source, is in the compressed state of about 7 kg/cm ². The compressed state of about 7 kg/cm ²is regulated to appropriate supply gas pressure, e.g. in the range of 1.2 to 1.5 kg/cm ², by a reduced pressure valve 124 , and the gas is introduced into the storage container main body 101 by opening the first valve 131 and the second valve 132 . The gas replacing step 206 is started immediately after the reduced pressure valve 205 is started. It is desirable that the gas replacing step 206 is performed after the insides of the storage container main body 101 and the dust collecting chamber 107 are evacuated to the high vacuum state. However, it is necessary to use the semiconductor wafer storage container having excellent withstanding pressure properties. Because the semiconductor wafer storage container is usually molded by a plastic material, from the viewpoint of withstanding pressure properties of the container, it is not preferable that the high vacuum state is made in the reduced pressure state 205 .

The introduced gas is the dry nitrogen gas having purity not lower than 95%, preferably the dry nitrogen gas having purity in the range of 99.9 to not lower than 99.999%. The supplied dry gas flows in a laminar flow between the semiconductor wafers 100 stored in the storage container main body 101 , and the gas flows into the pump chamber described in FIGS. 4A and 4B through the gap between the storage container main body 101 and the lid unit 102 . The formation of the pump chamber reduces passage resistance of the gap formed between the storage container main body 101 and the lid unit 102 . Further, at the same time, because the pump chamber becomes the reduced pressure state compared with the inside of the storage container main body 101 , the gas flowing through the gap flows into the pump chamber while gaining momentum. Therefore, the micro-dust adhering to the gap between the storage container main body 101 and the lid unit 102 is blown away and removed, which results in the cleaning of the surface. As the procedure is in progress, the gas pressure is gradually increased in the pump chamber. Because the volume of the dust collecting chamber 107 is sufficiently larger than that of the pump chamber, the pressure in the dust collecting chamber 107 is sufficiently smaller than that of pump chamber. Therefore, the gas and the micro-dust are discharged into the dust collecting chamber 107 from the gap between the gas passage forming mechanism 111 and the dust collecting wall 104 shown in FIGS. 4A and 4B and from the airflow gap. The gas passing through the airflow gap is discharged to the dust collecting chamber 107 through the communication hole 113 made in the gas passage forming mechanism 111 . The diameter of the communication hole 113 is formed so as to be gradually increased from the airflow gap toward the dust collecting chamber 107 , so that the passage resistance is reduced, and the gas passing through the airflow gap flows without decreasing speed. As a result, the gas flowing through the airflow gap removes the micro-dust adhering to the surface of the lid unit 102 .

The gas and the micro-dust which flow into the dust collecting chamber 107 are filtered by the dust collecting filter 130 , and the gas is exhausted outside the evacuation pump 127 through the fifth valve 135 and the evacuation pipe 138 . The gas flow in the gas replacing step 206 is shown by the arrow in FIG. 6.

The gas replacing step 206 is performed until the gas purity is sufficiently increased in the replacement gas passage and the micro-dust in the dust collecting chamber 107 is sufficiently adsorbed and filtered by the dust collecting filter 130 . After the gas replacement is performed for a sufficient time, the first valve 131 and the fifth valve 135 are continuously closed. Then, while the third valve 133 is opened to take the air from a gas outlet 123 A into the evacuation pipe, the evacuation pump 127 is stopped to end the gas replacing step 206 .

When the semiconductor wafer storage container is stored while the pressure is reduced in the semiconductor wafer storage container, the first valve 131 is closed first. When the semiconductor wafer storage container is stored while the pressure is increased in the semiconductor wafer storage container, the fifth valve 135 is closed first. When storage gas pressure is controlled, a vacuum gage is placed at an appropriate position in the gas passage, e.g. at the dust collecting wall 104 , and the valve can be opened and closed while the gas pressure in the gas passage is measured. Electromagnetic valves which can electrically be opened and closed are used as the valve shown in FIG. 6, and the open and close of the electromagnetic valves are controlled by a control circuit (not shown), which enables automation of the opening and closing operations of the valves.

Then, in a gas circulating step 207 , the gas is circulated in the order of the storage container main body, the dust collecting means, and the replacement gas inlet of the storage container. The gas circulating step 207 is one in which the fourth valve 134 shown in FIG. 7 is opened and a circulating pump 128 is operated to circulate the gas. The gas circulating step 207 forms the gas circulating passage in which the dry gas replaced in the gas replacing step 206 flows in the order of the circulating pump 128 , the gas introducing pipe 137 , the second valve 132 , the replacement gas inlet 126 , the storage container main body 102 , the dust collecting chamber 107 , the dust collecting filter 130 , the fourth valve 134 , a chemical adsorption filter 129 , and a circulated gas pipe 139 . In the gas circulating step 207 , the impurities and moisture adsorbed on the surfaces of the semiconductor wafers 100 are removed by the circulated gas and filtered by the chemical adsorption filter 129 , so that the surfaces of the semiconductor wafers 100 can be cleaned. In the configuration shown in FIG. 7, because the dust collecting filter 130 is included in the gas circulating passage, the micro-dust included in the circulated gas is filtered and cleaned even in circulated gas. The gas flow in the gas circulating step is shown by the arrow of FIG. 7. After the gas circulating step 207 is performed for a predetermined time, the circulating pump 128 is stopped, and the fourth valve 134 is closed to end the gas circulating step 207 .

In a lid unit mounting step 208 , both the lid unit latching structure detaching mechanism and the gas passage forming mechanism are moved to insert the lid unit into the storage container main body, and the lid unit latching structure is operated by the lid unit latching structure detaching mechanism to connect the storage container main body and the lid unit. The lid unit mounting step 208 is one which reverses the lid unit demounting step 204 and the lid unit holding step 203 . Namely, in FIG. 7, the lid unit latching structure detaching mechanism 114 , the gas passage forming mechanism 111 , and the lid unit 102 are moved by the detachment moving mechanism 112 to bring the lid unit 102 into close contact with the storage container main body 101 , the lid unit latching structure detaching mechanism 112 is rotated to insert the lid unit latching structure into the connection hole, and the storage container main body 101 and the lid unit 102 are connected in the airtight manner. Then, the lid unit latching structure detaching mechanism 114 and the gas passage forming mechanism 111 are moved by the detachment moving mechanism 112 to demount the lid unit latching structure detaching mechanism from the lid unit holding mechanism.

Then, in a gas introducing means demounting step 209 , the gas introducing means is demounted from the replacement gas inlet of the storage container main body. This step can easily be performed by disengaging the male die and the female die of the air tight maintaining type coupler 125 .

Finally, in a container demounting step 210 , the semiconductor wafer storage container is demounted from the dust collecting means. Then, the gas replacing method of the invention is ended.

In order to improve cleanness of the semiconductor wafer surface in a short time, a cleaning gas replacing step and a cleaning gas circulating step can be added between the reduced pressure step 205 and the gas replacing step 206 shown in FIG. 8. In this case, a flowchart of a method for replacing gas in a semiconductor wafer storage container of the invention is shown in FIG. 9. In the flowchart shown in FIG. 9, as described above, the gas replacing step 206 and the gas circulating step 207 shown in FIG. 8 are performed using the reactive gas which is mixed with the dry nitrogen gas to the extent of not more than about 5% as the replacement gas. Addition of the steps obtains the cleaning effect of the semiconductor wafer surface in a shorter time compared with the flowchart shown in FIG. 8.

As shown in FIG. 9, when a cleaning gas replacing step 211 and a cleaning gas circulating step 212 are performed, sometimes the reactive gas remains in the semiconductor wafer storage container to damage the semiconductor wafer surface in a time-varying manner, so that a nitrogen gas replacing step 213 and a nitrogen gas circulating step 214 are performed subsequent to the cleaning gas replacing step 211 and the cleaning gas circulating step 212 . The nitrogen gas replacing step 213 and the nitrogen gas circulating step 214 differ from the cleaning gas replacing step 211 and the cleaning gas circulating step 212 only in that the dry nitrogen gas having the purity not lower than 95% with no reactive gas is used. The nitrogen gas replacing step 213 and the nitrogen gas circulating step 214 are performed, which allows the semiconductor wafers to be stored in the semiconductor wafer storage container for a long time without damaging the semiconductor wafer surfaces.

When the method for replacing gas in a semiconductor wafer storage container of the invention shown in FIG. 8 is performed, first gas supply means for supplying the reactive gas and second gas supply means for supplying the nitrogen gas are used as the gas supply means. The reactive gas including at least one gas component of the ozone gas, the hydrogen gas, and the ammonia gas, which is mixed with the nitrogen gas in a proportion of not more than about 5%, can be used as the reactive gas supplied from the first gas supply means. It is possible that the reactive gas including at least one gas component of the ozone gas, the hydrogen gas, and the ammonia gas is mixed with the nitrogen gas supplied from the second gas supply means in a predetermined proportion. When the gases are mixed using the first gas supply means and the second gas supply means, a gas mixture ratio is adjusted with a gas flowmeter.

When a trace quantity of active gas is used in the cleaning gas replacing step 211 and the cleaning gas circulating step 212 , or when the reactive gas has the low reactivity, the nitrogen gas circulating step 214 can be omitted.

As described above, according to the apparatus for replacing gas in a semiconductor wafer storage container and the method for replacing gas therewith of the invention, while the atmosphere in the semiconductor wafer storage container can be replaced with the target gas in a short time, the semiconductor wafer surface can be cleaned by circulating the replacement gas. Therefore, the semiconductor wafer forming step suitable for high density can be realized. Since the gas replacement can be automatized, the gas replacing apparatus and the gas replacing method are compatible with the automatized load/unload system, and the contamination in the process room such as the clean room can be suppressed to a minimum level.

The apparatus for replacing gas in a storage container of the first embodiment is the apparatus for replacing the gas in the storage container which has the lid unit and the storage container main body with the replacement gas inlet. The apparatus includes gas introducing means for introducing the gas into the storage container main body, the gas evacuating means for evacuating the gas in the storage container main body, and the gas circulating means for circulating the gas in the storage container main body through the chemical adsorption filter.

The configuration of the gas replacing apparatus of the invention can realize the open-system gas replacing apparatus. As a result, the high-purity gas replacement can be performed in a short time by simultaneously evacuating the gas from and introducing the gas into the storage container, so that the above problem can be solved.

The semiconductor wafer surface can be cleaned in a short time at room temperature by circulating the gas in the storage container through the chemical adsorption filter, so that the above problem can be solved. Particularly, when the nitrogen gas or the nitrogen gas including the reactive gas not more than 5% is used as the circulated gas, the impurity elements and the functional groups adsorbed on the semiconductor wafer surface can efficiently be removed in a short time.

The storage container mounting means capable of mounting the storage container main body is provided so that the lid unit is entirely accommodated in the gas replacing passage, the evacuating means for evacuating the gas in the storage container main body through the storage container mounting means is mounted, and the gas circulating means capable of sequentially circulating the gas among the storage container main body, the storage container mounting means, and the replacement gas inlet is mounted. Therefore, the reverse flows of the introduced gas or the circulated gas can be prevented, the micro-dust adhering to the lid unit can be removed to realize the gas replacement with high cleanness in a short time, and the above problem can be solved.

The storage container mounting means includes: the dust collecting means for separating micro-dust generated during the gas replacing step, the dust collecting means being formed by the dust collecting chamber formed to be surrounded by at least a dust collecting wall; and the storage container main body mounting means for mounting the storage container on the storage container main body mounting means while airtightness is held, the lid unit being entirely accommodated inside the dust collecting chamber. Further, the lid unit detaching means for detaching the lid unit from the storage container main body inside the dust collecting means is configured. The lid unit detaching means includes the lid unit holding mechanism which holds the lid unit; a lid unit latching structure detaching mechanism which detaches the lid unit latching structure connecting the storage container main body and the lid unit; the gas flow forming mechanism which is brought close to the lid unit so as to have a predetermined gap, the gas flow forming mechanism forming the gas passage; the detachment moving mechanism which simultaneously moves the lid unit, the lid unit holding mechanism, the lid unit latching structure detaching mechanism, and the gas flow forming mechanism to form a predetermined gap between the storage container and the lid unit; and the detachment driving mechanism which separately drives the lid unit holding mechanism, the lid unit latching structure detaching mechanism, and the detachment moving mechanism. Therefore, the gas replacement of the semiconductor wafer storage container can mechanically automatized, the contamination in the clean room can be minimized, and the apparatus and method of the invention can be compatible with the load/unload process in the semiconductor process, so that the above problems can be solved.

The airtight maintaining seal is provided in the mating surface between the storage container main body and the storage container mounting means to prevent the leakage of the gas to the outside environment. Therefore, high-purity gas replacement is enabled.

The gas passage forming mechanism which is in contact with the lid unit while separated at the predetermined gap is formed to arrange a pump chamber whose volume of the gap formed in a circumferential portion of the lid unit is sufficiently larger than a volume of the gap formed in a central portion of the lid unit, and the gas passage forming mechanism which is in contact with the lid unit while separated at the predetermined gap has at least one communication hole which communicates the dust collecting chamber and the gap formed by the lid unit, the gap being exclusive of the pump chamber, the communication hole being made such that a diameter is gradually increased from the gas side toward the dust collecting chamber side. Therefore, the micro-dust adhering to the lid unit can efficiently be removed.

Both the lid unit latching structure detaching mechanism and the detachment moving mechanism are configured by the same rotating and moving shaft which is rotatable and movable in parallel, the rotating and moving shaft is rotatably connected in the gas passage forming mechanism by a fluorine-contained polymer bearing with an anti-disconnection latch, and the rotating and moving shaft is connected in the dust collecting wall by another fluorine-contained polymer bearing in an airtight manner while being rotatable and movable in parallel. Therefore, the apparatus configuration can be simplified, the apparatus can be configured so that the micro-dust is not generated, and the purity of the gas replacement can be improved.

On the other hand, a method for replacing gas in a storage container including the following steps of (a) to (e) is realized as the method for replacing the gas in the storage container using the apparatus for replacing gas in a storage container of the invention. The method for replacing gas in a storage container including the steps of: (a) mounting a storage container on a gas replacing apparatus; (b) evacuating air in a storage container main body with gas evacuating means; (c) introducing gas into the storage container main body with gas introducing means while the gas introducing means evacuates the gas in the storage container main body; (d) terminating introduction of the gas into and the evacuation of the gas from the storage container main body to cause gas circulating means to circulate the gas in the storage container main body through a chemical adsorption filter; and (e) demounting the storage container from the gas replacing apparatus.

According to the method for replacing gas in a storage container of the invention, the gas replacement and the cleaning of the semiconductor wafer can be realized in a short time, so that the above problems can be solved.

The effect of cleaning the semiconductor can be enhanced by using a dry gas including a not lower than 95% nitrogen gas.

A gas replacing method including the following steps (a) to (j) is disclosed as a method for replacing gas in a storage container using an apparatus for replacing gas in a container of the invention. The method includes the steps of: (a) mounting the storage container on storage container mounting means in an airtight manner while a lid unit is accommodated in a dust collecting chamber; (b) connecting a gas inlet of the storage container main body and gas introducing means; (c) bringing a gas passage forming mechanism and a lid unit latching structure detaching mechanism close to the lid unit by simultaneously moving the gas passage forming mechanism and the lid unit latching structure detaching mechanism, and connecting and holding the lid unit by a lid unit holding mechanism; (d) operating a lid unit latching structure to separate the storage container main body and the lid unit by the lid unit latching structure detaching mechanism, the lid unit latching structure connecting the storage container main body and the lid unit; (e) evacuating the dust collecting chamber by evacuating means to reduce pressure; (f) introducing the gas into the storage container main body from the gas inlet of the storage container main body by gas introducing means, while the evacuating means evacuates the dust collecting chamber; (g) circulating the gas in the order of the storage container main body, the dust collecting means, and the gas inlet of the storage container; (h) inserting the lid unit into the storage container main body by simultaneously moving the gas passage forming mechanism, the lid unit latching structure detaching mechanism, and the lid unit, and operating the lid unit latching structure to connect the storage container main body and the lid unit by the lid unit latching structure detaching mechanism; (i) demounting the gas introducing means from the gas inlet of the storage container main body; and (j) demounting the storage container from the dust collecting means.

According to the gas replacing method of the invention, the gas replacement of the storage container can automatically or semi-automatically be realized, the high-purity gas replacement and the cleaning of the semiconductor wafer can be realized in a short time, so that the above problems can be solved.

Further, the following steps (s) and (t) are added prior to the step (h) of the above gas replacing method of the invention. Therefore, the cleaning of the semiconductor wafer can effectively be performed in a shorter time. Namely, the gas replacing method of the invention further including the steps of (s) introducing a cleaning gas into the storage container main body from a gas inlet of the storage container main body by gas introducing means while the evacuating means evacuates the dust collecting chamber, a not more than 5% reactive gas being mixed with a dry nitrogen gas in the cleaning gas; and (t) circulating the cleaning gas in the order of the storage container main body, the dust collecting means, and the gas inlet of the storage container.

The effect of cleaning the semiconductor can be enhanced by using the dry nitrogen gas including at least one gas component of an ozone gas, a hydrogen gas, and an ammonia gas as the reactive gas.

Second Embodiment

A second embodiment of the invention will be described referring to the drawings. Even in the second embodiment, the semiconductor wafer storage container in which the semiconductor wafers are stored will be described by way of illustration as the storage container whose inside is necessary to keep clean. However, the invention is not limited to the semiconductor wafer, but the invention can be also applied to the storage container for any precision part such as ICs for which a storage space is necessary to keep clean.

FIG. 11 shows a basic configuration of an apparatus for replacing gas in a semiconductor wafer storage container according to the invention. A semiconductor wafer storage container includes a storage container main body 301 whose inside is necessary to keep clean and a lid unit 302 which seals the inside of the storage container main body 301 . The semiconductor wafer storage container has the sealed structure with the seal so that the moisture and dust in the atmosphere are prevented from intruding into the container. In the storage container main body 301 of the sealed semiconductor wafer storage container, the semiconductor wafers are stored in parallel while separated from one another with predetermined intervals by groove plates (not shown).

A semiconductor wafer storage container mounting means 303 in FIG. 11 is the device which replaces the gas in the storage container main body 301 . In the state in which the semiconductor wafer storage container mounting means 303 is mounted on the storage container main body 301 while a lid unit 302 is entirely covered with the semiconductor wafer storage container mounting means 303 , the semiconductor wafer storage container mounting means 303 demounts the lid unit 302 to put in and take out the gas. The seal (not shown) is provided in an engagement portion between the semiconductor wafer storage container mounting means 303 and the storage container main body 301 , and the storage container main body 301 is mounted on the semiconductor wafer storage container mounting means 303 in an airtight manner by the seal. Therefore, while the storage container main body 301 is mounted on the semiconductor wafer storage container mounting means 303 , the lid unit 302 is mounted in the air tight manner so as to be entirely accommodated in a gas replacement passage formed in the semiconductor wafer storage container mounting means 303 . As a result, the lid unit 302 is demounted from the storage container main body 301 , which allows the inside of the storage container main body 301 to be connected to the gas replacement passage while the airtightness is maintained. A mechanism which grasps and fixes the storage container main body 301 (later-mentioned storage container main body mounting means 407 and the like) is provided in the semiconductor wafer storage container mounting means 303 .

On the other hand, the gas piping from gas supply means 308 is coupled to the semiconductor wafer storage container mounting means 303 , the introduction and stop of the gas into the semiconductor wafer storage container mounting means 303 can be controlled by opening and closing a first valve 317 . Namely, the gas introducing means includes the gas supply means 308 , the gas piping connected to the gas supply means 308 , and the first valve 317 .

An evacuation pump 309 is connected to the semiconductor wafer storage container mounting means 303 through the gas piping, which forms the gas evacuating means for evacuating the gas in the storage container main body 301 . The gas evacuating means includes a dust collecting filter 313 , a fourth valve 319 , and a fifth valve 320 as an opening and closing valve. When the evacuation pump 309 is operated to open the fourth valve 319 while the fifth valve 320 is closed, the gas in the semiconductor wafer storage container mounting means 303 can directly be evacuated, and the gas in the storage container main body 301 can indirectly be evacuated. The micro-dust contained in the evacuated gas is removed by the dust collecting filter 313 . The dust collecting filter 313 also has the function of preventing the micro-dust from reversely flowing into the semiconductor wafer storage container mounting means 303 from the evacuation pump 309 side.

The oil-sealed rotary vacuum pump can be used as the evacuation pump 309 . In this case, the oil-mist generated from the oil-sealed rotary vacuum pump is filtered by an oil-mist trap and the like and exhausted from an exhaust duct (not shown).

In the case of the use of the evacuation pump such as the oil-sealed rotary vacuum pump which generates the oil-mist and the like, the fifth valve 320 is opened after the fourth valve 319 is closed, the gas piping immediately in front of the evacuation pump 309 is returned to the atmospheric pressure, and the evacuation pump 309 is stopped so that the oil-mist reversely flow toward the semiconductor wafer storage container mounting means 303 .

The gas circulating means for circulating the gas with a circulating pump 311 is mounted on the semiconductor wafer storage container mounting means 303 . A chemical adsorption filter 310 , a dust collecting filter 312 , a second valve 318 , and a third valve 321 are inserted into a gas circulating passage formed by the gas circulating means. The chemical adsorption filter 310 has the function of adsorbing and filtering the impurity gas components contained in the circulated gas. In the chemical adsorption filter 310 , the moisture and impurities in the gas are removed by passing the gas through the chemical adsorbent encapsulated in the stainless-steel vessel. Well-known examples of the chemical adsorbent include metal meshes made of stainless steel or nickel whose surface is activated, porous glass fiber, and ceramic materials such as porous alumina. Both the second valve 318 and the third valve 321 are closed during the gas introduction and evacuation. The gas circulating passage is formed by opening the second valve 318 and the third valve 321 . The dust collecting filter 312 removes the micro-dust by its fine mesh structure.

The storage container main body 301 is mounted on the moving means. The moving means includes a moving stage 314 and a base 316 . The moving stage 314 is the member which is directly mounted on the storage container main body 301 to support the storage container main body 301 . The moving stage 314 is mounted on the storage container main body 301 by mounting means 315 such as a mechanical pin. The base 316 is the member which supports the moving stage 314 . The moving stage 314 is adopted to be moved in parallel on the base 316 while supported by the base 316 . Position detection means (not shown) is provided in the base 316 . The position detection means includes a photosensor and a micro-mechanical switch. The position detection means can detect the precise position (precise position with respect to the semiconductor wafer storage container mounting means 303 ) of the storage container main body 301 mounted on the moving stage 314 . Therefore, when the storage container main body 301 is moved by the moving stage 314 to come into close contact with the semiconductor wafer storage container mounting means 303 , the position detection means detects the position of the storage container main body 301 which is in close contact with the semiconductor wafer storage container mounting means 303 . Further, the position detection means is connected to the mechanism which fixes the storage container main body 301 , and the position detection means transmits a detection signal indicating the position of the storage container main body 301 . The semiconductor wafer storage container mounting means 303 is operated according to the detection signal to fix the storage container main body 301 in the airtight manner. In the case the semiconductor wafer storage container is manually mounted, the moving stage 314 and the base 316 are not required. The airtight maintaining seal is provided in the mating surface between the storage container main body 301 and the semiconductor wafer storage container mounting means 303 , and the storage container main body 301 and the semiconductor wafer storage container mounting means 303 are mounted by mechanically pressing against each other.

The inside of the semiconductor wafer storage container mounting means 303 has a space in which the lid unit 302 can freely be moved to be opened and closed while the semiconductor wafer storage container mounting means 303 is coupled to the storage container main body 301 . The space constitutes apart of the gas replacing passage which is closed from the environment.

Lid unit detaching means 304 and lid unit detaching control means 305 are provided in the semiconductor wafer storage container mounting means 303 . The lid unit detaching means 304 detaches the lid unit 302 from the storage container main body 301 inside the semiconductor wafer storage container mounting means 303 . The lid unit detaching control means 305 controls the action of the lid unit detaching means 304 . The lid unit detaching means 304 is coupled to the lid unit 302 to operate fixation and release of the lid unit 302 with respect to the storage container main body 301 . The lid unit detaching means 304 also separates the lid unit 302 , which is released from the fixation, from the storage container main body 301 . The lid unit detaching control means 305 controls the above actions of the lid unit detaching means 304 .

Gas passage switching means includes the third valve 321 and the fourth valve 319 . These valves are automatically or manually switched according to the procedure.

The method for replacing the gas with the gas replacing apparatus shown in FIG. 11 will be described below.

In a first step, the semiconductor wafer storage container 1 is mounted on the moving stage 314 , and the semiconductor wafer storage container 1 is moved to be mounted on the semiconductor wafer storage container mounting means 303 .

In a second step, the lid unit 302 is demounted from the storage container main body 301 by the lid unit detaching means 304 to form a predetermined gap between the lid unit 302 and the storage container main body 301 , and the inside of the storage container main body 301 is connected to the gas replacing passage in the semiconductor wafer storage container mounting means 303 . Lid unit detaching control means 305 controls the lid unit detaching means 304 .

In a third step, the evacuating means is operated to start the evacuation of the air in the semiconductor wafer storage container. In the operation of the evacuating means, the fourth valve 319 and the fifth valve 320 are closed, the evacuation pump 309 is operated, and the fourth valve 319 is opened to evacuate the gas in the semiconductor wafer storage container mounting means 303 . In this step, the inside of storage container main body 301 is simultaneously evacuated.

In a fourth step, while the gas is evacuated by the gas evacuating means, the gas is introduced from the gas introducing means into the semiconductor wafer storage container. Specifically, the first valve 317 is opened to introduce the gas the gas supply means 308 into the semiconductor wafer storage container mounting means 303 . At this point, in the gas flowing into the semiconductor wafer storage container mounting means 303 from the third valve 321 side, when the gas passes through between the largely opened lid unit 302 and the storage container main body 301 to be circulated to the second valve 318 side, the coming and going of the gas occur in the storage container main body 301 and the semiconductor wafer storage container mounting means 303 , which allows the gas to be entirely replaced in the storage container main body 301 .

The high-purity dry nitrogen gas is used as the gas used in the fourth step. According to the processing status of the semiconductor wafers in the container, sometimes dry argon gas is used. Further, for the purpose of the cost reduction, sometimes the gas in which dry air is mixed with the high-purity dry nitrogen gas is used. In this case, it is desirable that at least 95% nitrogen gas is contained in the mixture gas.

At the time when the fourth step is started, it is not necessary that the inside of the semiconductor wafer storage container 1 is evacuated in high vacuum, but is sufficient that the semiconductor wafer storage container 1 is evacuated in a reduced-pressure state. The many conventional gas replacing apparatuses have closed-system structures in which one port is used for both the gas inlet and the gas outlet. In the conventional gas replacing apparatus, when the gas remains in the semiconductor wafer storage container before the fourth step, because the residual gas affects the replacement gas purity, it takes at least 30 to 60 minutes to replace the gas. On the contrary, the gas replacing apparatus according to the invention has an open-system structure, so that the gas in the semiconductor wafer storage container 1 is efficiently replaced by performing the gas introduction and the gas evacuation at the same time.

After the gas introduction and the gas evacuation are performed for a given time in the fourth step, the gas introduction from the gas introducing means to the semiconductor wafer storage container and the gas evacuation from the semiconductor wafer storage container by the gas evacuating means are stopped in a fifth step. Specifically, at the same time when the first valve 317 is closed to stop the gas supply from the gas supply means 308 , the fourth valve 319 is closed. Then, after the fifth valve 320 is opened, the evacuation pump 309 is stopped. The time necessary for the fourth step depends on the volume of the semiconductor wafer storage container or the processing status of the semiconductor wafer. Typically, for the semiconductor wafer storage container having the volume of about 60 liters, it takes at least about 10 to 30 minutes to perform the fourth step.

Then, in a sixth step, the gas in the semiconductor wafer storage container is circulated with the gas circulating means. Specifically, the second valve 318 and the third valve 321 are opened, and the circulating pump 311 is operated to circulate the gas replaced in the fifth step. At this point, the circulated gas has the function of removing the impurities and functional groups on the surface of the semiconductor wafers. The chemical adsorption filter 310 adsorbs the moisture and impurity elements to clean the circulated gas. At this point, in the semiconductor wafer storage container, the lid unit 302 is demounted, and the inside of the storage container main body 301 is communicated with the circulating gas passage, so that the gas in the storage container main body 301 is replaced. It takes about 5 to 30 minutes to circulate the gas.

When the high-purity dry nitrogen gas having the purity in the range of about 99.5% to about 99.999% is used as the gas introduced in the fourth step, the moisture and impurities adsorbed on the semiconductor wafer surfaces can be efficiently removed in the sixth step.

In the gas introduced in the fourth step, the not more than about 5% reactive gas is mixed with the high-purity dry nitrogen gas not lower than 99% in purity. The reactive gas includes the ozone gas, the hydrogen gas, the ammonia gas having the purity not lower than 99%, or the reactive gas includes the mixture gas of the above-described gases. Therefore, in the sixth step, the effect of removing the moisture and impurities adsorbed on the semiconductor wafer surfaces is enhanced, and the surface cleaning effect is obtained in about 5 to 10 minutes.

Thus, in the case where the dry nitrogen gas with which the reactive gas is mixed is used in the fourth step, in order to prevent the reactive gas from remaining in the semiconductor wafer storage container, the steps from the fourth step to the sixth step are repeated using the high-purity dry nitrogen gas in which the reactive gas is not included.

After the sixth step, in a seventh step, the second valve 318 and the third valve 321 are closed to stop the gas circulation. Then, the lid unit 302 is mounted on the storage container main body 301 by the lid unit detaching means 304 , the gas is inserted into the storage container main body 301 in the airtight manner, and the semiconductor wafer storage container is demounted from the semiconductor wafer storage container mounting means 303 to end the gas replacing step. It is possible that the semiconductor wafer storage container is manually demounted from the semiconductor wafer storage container mounting means 303 , or it is possible that the semiconductor wafer storage container is automatically demounted from the semiconductor wafer storage container mounting means 303 using the moving stage 314 . In the automatic operation, the demounting is performed according to time control which is previously determined by the conditions.

Third Embodiment

A third embodiment of the invention will be described. FIG. 12 shows a configuration of a gas replacing apparatus according to the third embodiment of the invention. In FIG. 12, the same element as for FIG. 11 is indicated by the same reference numeral, and the description of the element is omitted. The third embodiment shown in FIG. 12 differs from the second embodiment shown in FIG. 11 in that a gas introducing nozzle 306 and nozzle moving means 307 are provided in the gas introducing means.

The gas introducing nozzle 306 is one which introduces the gas into the deep portion in the storage container main body 301 from a gap between the storage container main body 301 and the lid unit 302

4724874	Sealable transportable container having a particle filtering system	February, 1988	Parikh et al.	141/98
5238503	Device for decontaminating a semiconductor wafer container	August, 1993	Phenix et al.	134/37
5586585	Direct loadlock interface	December, 1996	Bonora et al.	141/93
6470927	Foup opener	October, 2002	Otaguro	141/98
6533000	Substrate transportation container	March, 2003	Saga	141/98
20020124906	Substrate transport apparatus, POD and method	September, 2002	Suzuki et al.	141/98

JP05074921	March, 1993
JP11317442	November, 1999	METHOD OF STORING WAFER
JP2000311936	November, 2000	WAFER ACCOMMODATION METHOD AND WAFER CASE USED THEREFOR