JP2007119072A - Clean box - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a clean box which is made not only to efficiently avoid contamination from an external atmosphere to a stored substrate but also to effectively prevent contamination generated from the substrate itself and an internal structure member. <P>SOLUTION: The clean box is equipped with a retaining container 18 formed by the container body 12 for holding the substrate and a lid 14 for covering an opening hereof so as to be able to seal, a motor fan 30 for forming the circulating flow of an air current on the substrate with which comes into contact in the container body 12, a particle eliminating filter 26 and a gas-like impurity capturing filter 28 arranged in the passage of the air current flowing toward the substrate and a dehumidifier 54 arranged in the container body 12, and the retaining container 18 is made of a resin in which an anti-static agent is mixed. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a clean box suitable for use in storing or transporting an object to be processed such as a semiconductor wafer, a photomask or a hard disk in an extremely clean atmosphere.

  For example, when transporting and storing substrates such as semiconductor wafers and photomasks manufactured in semiconductor factories, product yield decreases when trace amounts of dust and gaseous impurities present in atmospheric air adhere to objects such as semiconductor wafers. This tendency becomes more pronounced as the degree of integration increases. Also in magnetic disks, with the advent of magnetoresistive heads, the recording density is further accelerated, and high cleanliness against not only dust but also gaseous impurities is being demanded. Furthermore, from the viewpoint of reducing the corrosion of the semiconductor substrate, there is also a demand for a simple means for keeping the humidity of the atmosphere in which the substrate is stored low.

  In order to create a clean space that accommodates substrates for such transportation and storage, a clean box equipped with a motor fan and a high efficiency particle air (HEPA) filter or ULPA (ultra low penetration air) filter has been developed. Yes. In addition, for example, as a method of locally cleaning the periphery of a semiconductor wafer, a clean box containing a semiconductor wafer is replaced with high-purity nitrogen to suppress the maintenance of cleanliness and the growth of a natural oxide film. is there.

  However, with the use of the HEPA filter or ULPA filter, particulate contaminants can be removed, but trace amounts of organic or inorganic gases cannot be removed. In addition, if the circulating air flows in a large amount in a part that does not directly contribute to the purification of the object to be processed, or if there is a stagnant part in the clean box, the ventilation efficiency in the clean box cannot be improved, and the purified air The anti-contamination effect of the object to be processed will be diminished. Further, in the method of substituting with nitrogen, for example, impurities generated from the semiconductor wafer itself coated with resist or the like cannot be removed, and there is a safety problem due to the use of nitrogen.

  In view of the above-described problems, the present invention not only efficiently prevents contamination of the housed substrate from the external atmosphere, but also effectively prevents contamination generated from the substrate itself and internal components. The purpose is to provide a clean box.

  One aspect of the clean box of the present invention is a holding container configured by a container main body for housing a substrate and a lid body that covers the opening of the container in a sealable manner, and an air flow that contacts the substrate in the container main body. A motor fan that forms a circulating flow of the above, a particle removal filter and a gaseous impurity trapping filter disposed in a flow path of the airflow flowing toward the substrate, and a dehumidifying agent disposed in the container body, The holding container is composed of a resin mixed with an antistatic agent.

According to a preferred aspect of the present invention, a control unit for controlling the operation of the motor fan is provided.
According to a preferred aspect of the present invention, the airflow flows substantially parallel to the main surface of the substrate.

According to a preferred aspect of the present invention, a filter for preventing a backflow of contaminants from the motor fan is disposed on the downstream side of the substrate holding part of the circulating flow.
According to a preferred aspect of the present invention, the dehumidifying agent is provided on the downstream side of the substrate holding part of the circulating flow and on the upstream side of the motor fan.
According to a preferred aspect of the present invention, the gaseous impurity trapping filter is a chemical filter.

  The clean box of the present invention forms a holding container composed of a container main body and a lid that covers the upper opening of the container so as to be hermetically sealed, and a circulation channel having an ascending channel and a descending channel in the holding container. A partition wall that is disposed in the ascending flow path, a substrate holding portion that holds the substrate with its main surface substantially parallel to the ascending flow path, and an upstream side of the substrate holding portion in the ascending flow path You may make it have a motor fan which forms the circulating airflow which is incorporated in the said holding | maintenance container and circulates through the said circulation flow path.

  In this way, a circulation flow is formed in the holding container, and this is physically and chemically cleaned by the particle removal filter and the chemical filter and then flowed toward the substrate holding part. Even if there is a contamination source such as particles adhering to the substrate itself or gas generated from the container, it is prevented that this contaminates the substrate in the substrate holder. Since the particle removal filter and the chemical filter are arranged on the upstream side of the substrate holding portion of the ascending flow path, the substrate can be easily taken in and out from above. Further, since the lid of the container is on the downstream side of the substrate holding portion, it is possible to prevent the substrate from being contaminated from a container that is easily soiled during opening and closing.

  As the membrane material of the chemical filter, an ion exchange fiber and activated carbon fiber or activated carbon in which a granular activated carbon is supported on a urethane foam alone or in combination, or those in which these are simultaneously woven and integrated can be used. Ion exchange fibers and activated carbon fibers activated by carbonization of cellulose, acrylic and lignin fibers efficiently adsorb ions such as ammonia present in the air or ionic substances such as hydrofluoric acid and hydrochloric acid contained in mist. Can be removed. What was manufactured by the radiation graft polymerization reaction can be used for an ion exchange fiber.

  The ascending flow path is formed at substantially the center of the holding container, and is reversed by a reversing portion having an arcuate surface or a spherical surface at the top and / or bottom of the holding container, and between the partition wall and the side wall of the container body. You may come to communicate with the formed said downward flow path. By forming the lid and / or bottom of the top of the holding container into a circular or spherical dome shape, the entire container is smooth and free from stagnation. Therefore, it can operate for a long time with one battery with little energy loss. It becomes possible. The radius of curvature of the arc surface or spherical surface is preferably 1.2 R or more with respect to the radius R of the substrate to be accommodated.

In addition, guide protrusions that branch the ascending flow path may be formed on the inner surface of the lid and the bottom surface of the container body. Usually, this is formed in a triangular prism shape in cross section.
In addition, a filter for preventing a backflow of contaminants from the motor fan may be disposed on the downstream side of the substrate holding portion of the circulation flow path. Thereby, even if the operation of the motor fan is stopped, the substrate is not directly contaminated by contaminants from the motor fan.

  In addition, it is preferable that the motor of the motor fan is a direct current brushless motor. Thereby, since there is no brush which is a sliding portion, generation of contaminants is reduced. Further, for example, a motor of a type in which the coil is covered and sealed with stainless steel having a thickness of 0.2 mm or less to have a dustproof and gasproof structure may be used. Thereby, it is possible to prevent gaseous contaminants from the coils constituting the motor fan and the motor fan itself from becoming a source of contamination.

Further, the substrate holding part may be a carrier receiving part that removably receives a carrier that opens at least up and down and accommodates the plurality of substrates. Thereby, a board | substrate can be stored and conveyed per carrier.
The substrate holding part may be provided with guide grooves that directly receive the plurality of substrates. In this way, by accommodating the substrate without using the carrier, the clean box can be made compact and lightweight.

In addition, a plurality of the substrates may be accommodated in the substrate holding unit, and a diffusion plate that disperses the circulating gas between the substrates may be provided upstream of the substrate holding unit. Thereby, air can be evenly circulated through the gaps between the plurality of substrates, and cleaning can be performed efficiently.
Moreover, you may make it have a control part which controls the driving | operation of the said motor fan. Thus, a predetermined operation control pattern is stored in the microchip or the like, and along with this, for example, by operating intermittently or by changing the rotation speed, it is possible to operate for a long time while preventing contamination. It is possible to perform.

Moreover, you may make it the structural article inside the said container main body assembled | attached to the said container main body, without using a fixing jig. Thereby, the contamination which generate | occur | produces by clamp | tightening of a fixing jig etc. can be prevented, and taking out from the container main body, washing | cleaning, and replacement | exchange can be performed easily.
Moreover, you may make it hold | maintain low humidity by accommodating the sheet-like or bag-shaped dehumidifier inside the said container main body. By circulating the air in the holding container with a motor fan, the humidity can be reduced in a short time.

The chemical filter membrane material may be an ion exchange nonwoven fabric or a woven fabric produced by a radiation graft polymerization method.
Further, the chemical filter membrane material may be activated carbon in which granular activated carbon is supported on activated carbon fiber or urethane foam.
The chemical filter membrane material may be used in combination with an ion exchange nonwoven fabric or woven fabric produced by a radiation graft polymerization method and activated carbon in which granular activated carbon is supported on activated carbon fibers or urethane foam.

  According to the present invention, a circulation flow is formed in the holding container, which is physically and chemically cleaned by the particle removal filter and the chemical filter and then flows toward the substrate holding portion. In addition to efficiently preventing contamination from the atmosphere, it is possible to provide a clean box that can effectively prevent contamination generated from the substrate itself. As a result, particulate and gaseous impurities can be provided. It is possible to contribute to the improvement of the manufacturing yield and the quality of semiconductor wafers, photomasks and the like that must be avoided extremely. Since the particle removal filter and the chemical filter are arranged on the upstream side of the substrate holding part of the ascending flow path, the substrate can be easily taken in and out from above, and the container lid is located downstream of the substrate holding part. Therefore, it is possible to prevent the substrate from being contaminated from a container that is easily soiled during opening and closing. Furthermore, by storing the dehumidifying agent in the clean box and circulating the air in the box, the relative humidity can be reduced to 25% or less in a short time, which can contribute to the reduction of the corrosion of the substrate.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 to 3 show a clean box according to a first embodiment of the present invention, in which a plurality of semiconductor wafers (substrates to be processed) Wf are accommodated in a carrier 10 and transported.・ Stores etc. This clean box is composed of a rectangular tube-shaped container body 12, a lid body 14 that covers the opening on the upper end side of the container body so as to be openable and closable, and a bottom plate part 16 that covers the opening on the lower end side. An airtight holding container 18 is configured by being closely connected.

  The material of the holding container 18, that is, the container main body 12, the lid body 14, and the bottom plate portion 16, is expensive engineering plastic or fluororesin, for example, polycarbonate, polytetrafluoroethylene, There is no necessity to use butylene terephthalate, polyetheretherketone, etc., and it is possible to use relatively inexpensive materials such as polypropylene, acrylonitrile, butadiene, styrene resin and the like, which have good moldability and processability. You may use what mixed the antistatic agent in these.

  The interior of the container body 12 is partitioned into a central central chamber 22a and a pair of side chambers 22b located on both sides of the central chamber 22a by a pair of left and right partition plates 20 having a gap between the lid body 14 and the bottom plate portion 16. ing. A carrier support 24 having a tapered portion that extends upward so as to engage with the tapered portion of the lower portion of the carrier 10 is integrally provided on the upper portion of each partition plate 20.

  Below the carrier support 24 in the central chamber 22a, a particle removal filter 26 mainly for removing particles and a chemical filter 28 for removing impurity gas are able to circulate air in the vertical direction. It is arranged detachably. On the other hand, in each side chamber 22b, a direct current brushless motor fan 30 is disposed so as to send air downward, and a chemical filter 32 for backflow prevention is installed immediately above the motor fan 30.

  The ceiling portion 14a of the lid body 14 is formed in a shape that is smoothly curved inward, and a triangular upper rectifying plate 34 is provided at the center thereof. Similarly, the inner surface 16a of the bottom plate portion 16 is also formed in an inwardly curved shape, and a triangular lower rectifying plate 36 is provided at the center thereof. A carrier inlet rectifying plate 38 is also provided below the carrier support 24.

  In the case of a typical 25-sheet storage wafer carrier 10 as an example, the gap between the first and 25th wafers Wf and the carrier body is wider than the gap between the other wafers Wf. Hinders uniform flow rate to By providing the carrier inlet current plate 38, the flow rate between the first and 25th wafers Wf and the gap between the carrier bodies can be made uniform in the air inlet portion, and the cleaning can be performed efficiently. .

  A mounting slot 40a for detachably holding the power supply unit 40 is formed on the side surface of the container body, and a terminal for connecting the power supply terminal of the power supply unit 40 to the terminal of the motor fan 30 is provided. A control device is built in the power supply unit 40. When the power supply unit 40 is installed in the slot 40a, the DC brushless motor fan 30 operates / stops in accordance with a control program inputted in advance to the control device. And the rotation speed is controlled.

  The components in this clean box are assembled by sequentially stacking the parts without using any fixing tools such as screws, as shown in FIG. 3, except for the partition plate that is integrally bonded to the container body. It has been. That is, the filters 26 and 28 arranged in the central chamber 22a are sequentially placed on the upper frame 16b of the bottom plate portion 16 and held in the central chamber 22a. In the side chamber 22b, a support base 44 to which the DC brushless motor fan 30 can be attached is placed on the upper frame 16b, and a chemical filter 32 for backflow prevention is placed on the support base 44 and stored. As a result, it is possible to eliminate the tightening portion that becomes a dust generation source and to easily perform the disassembly work of the holding container 18 for cleaning or the like.

  In this embodiment, the chemical filter 28 is formed by weaving ion-exchange fibers and activated carbon fibers at the same time. The chemical filter 28 is formed by wrapping an ion-exchange nonwoven fabric in activated carbon in which granular activated carbon is supported on a urethane foam. Also good. The activated carbon fiber is, for example, rayon, kainol, polyacrylonitrile, petroleum, petroleum pitch, and carbonized into a fiber shape with water vapor, carbon dioxide gas, etc. at a high temperature of 800 ° C. or higher, so-called activation. It can be obtained by reacting. Some activated carbon fibers contain a binder or the like that does not contribute to adsorption for the purpose of maintaining strength and preventing dust generation. However, it is desirable that the content of the binder or the like is low as a material.

  Activated carbon has a large number of pores between basic crystals by removing unstructured carbon and the like during the activation process. Due to the pores and the large specific surface area, the activated carbon has a large physical adsorption. Utilizing this property, activated carbon filters filled with granular activated carbon are commercially available. In addition, as an air filter membrane material, it is suitable for filters using activated carbon fibers with less dust generation, better processability, finer pores than granular activated carbon and a large specific surface area, and urethane foam with an open porous structure. A filter carrying granular activated carbon having a diameter of about 0.5 mm is also commercially available.

  On the other hand, an ion exchange fiber can be obtained, for example, by introducing an ion exchange group by a radiation graft polymerization reaction. That is, a substrate composed of an organic polymer, such as a polymer such as polyethylene or polypropylene, or a natural polymer fiber or woven fabric such as cotton or wool, is first irradiated with radiation such as an electron beam or gamma ray to obtain a large amount of activity. Generate points. This active site is called a radical having a very high reactivity, and by chemically bonding the monomer to this radical, the property of the monomer different from the property of the substrate can be imparted.

  This technique is called graft polymerization because the monomer is added to the base material. When a monomer having a sulfone group, carboxyl group, amino group, or the like, which is an ion exchange group, such as sodium styrene sulfonate, acrylic acid, or arylamine is bonded to a polyethylene nonwoven fabric substrate by radiation graft polymerization, it is usually ion exchange. A non-woven ion exchanger having an ion exchange rate much faster than that of an ion exchange bead called a resin can be obtained.

Similarly, if ion-exchange groups are introduced after ion-grafting groups such as styrene, chloromethylstyrene, glycidyl methacrylate, acrylonitrile, or acrolein, which are monomers capable of introducing ion-exchange groups, are subjected to radiation graft polymerization. An ion exchanger can be formed in the shape of the material.
In this embodiment, an example in which the chemical filter 28 is configured by weaving the ion exchange fiber and the activated carbon fiber at the same time is shown, but the chemical filter is configured by combining the ion exchange fiber and the activated carbon fiber singly or in combination. You may make it do.

Next, the particle removal filter 26 will be described. The HEPA filter is an air filter having a particle collection efficiency of 99.97% or more with respect to particles having a rated air volume and a particle diameter of 0.3 μm. However, in the 1980s, with the improvement of integration of semiconductor-related VLSIs, a clean room with a cleanliness of class 10 (10 / ft ³ ) or less is required, and the collection efficiency is higher than that of HEPA filters. A high filter has been required. Correspondingly, a ULPA filter having a balance collection efficiency of 99.9995% or more for particles having a particle diameter of 0.1 μm was commercialized.

Initially, glass fiber was used for the filter material of the ULPA filter, but it was found that the glass fiber reacts with hydrogen fluoride (HF) vapor used in the manufacturing process of the semiconductor element to produce BF ₃ . It has become a problem. In recent years, ULPA filters using PTFE (polytetrafluoroethylene), which is free from impurities such as boron and metals, and is not affected by acids, alkalis, organic solvents, etc., as a filter medium have been commercialized. Here, glass fiber and PTFE may be properly used as necessary.

  Next, the dehumidifying agent will be described. Various types of dehumidifiers are commercially available, but typical materials include silica gel, molecular sieve, synthetic zeolite, chemical dehumidifier, calcium chloride, magnesium chloride. Etc. Any dehumidifying agent may be used in the clean box, but a physical dehumidifying agent that emits less particulate, inorganic, and organic gaseous contaminants is desirable.

  The operation of the clean box configured as described above will be described. The space inside the holding container 18 is kept clean in advance, and the filters 26, 28, 32, the power supply unit 40, etc. are stored in predetermined locations. In a clean environment such as a clean room, the lid is removed, the carrier 10 containing the wafer Wf is placed on the carrier support 24, and the lid 14 is put on and tightly fixed. Since the carrier support 24 is located above the two filters 26 and 28, the carrier 10 can be easily stored.

  When the external switch is turned on, the motor fan 30 is operated according to a preset program. As a result, a circulation path is formed for the air that descends the side chamber 22b, rises up the central chamber 22a, branches into two at the top, and descends the side chamber 22b and returns to the fan 30, respectively. That is, the air sent downward by the direct current brushless motor fan 30 flows along the floor surface 16a of the bottom plate portion 16, and then the direction is changed upward by the lower rectifying plate 36 to join together. Flows into the road.

  Here, the air passes through the chemical filter 28 and the ULPA filter 26 to be purified, and is guided to the gap between the wafers Wf by the carrier inlet current plate 38 disposed below the carrier support 24. By providing the carrier inlet current plate 38, it is possible to prevent an excessive flow in the gap between the wafer Wf and the carrier body. The air that has passed between the wafers Wf flows along the upper rectifying plate 34 and the inner surface 14a of the lid body 14 and reverses, descends the side chamber 22b, passes through the filter 32, is purified, and returns to the motor fan 30. .

  In this process, solid substances such as particles adhering to each part or gaseous substances generated from them are carried to the circulating airflow, cleaned by the two filters 26 and 28 on the upstream side of the wafer Wf, and then flow to the wafer Wf. . Therefore, not only contamination from the outside, but also so-called self-contamination from objects inside the container is prevented. Further, since the wafer Wf is held in the ascending flow path and is located upstream from the lid body 14 that is easily contaminated by the outside air when opening and closing, contamination from now on is prevented.

As an operation pattern of the motor fan 30, an appropriate mode can be considered according to the use state of the clean box. In general, the operation is initially performed continuously or at a higher flow rate, and the operation is actively performed to remove contamination brought from the outside into the container. After a certain period of time has elapsed, the flow rate is reduced or the operation is intermittently performed to prevent the contamination generated from the contained wafer Wf and the components in the container. Thereby, the lifetime of a power supply can be extended.
Here, when the motor fan 30 is stopped in intermittent operation, even if contaminants are generated from the motor, the backflow prevention filter 32 is provided, so that this backflows to the wafer Wf side and directly contaminates the wafer Wf. Is prevented.

  4 and 5 show a second embodiment of the present invention. The difference of this embodiment from the first embodiment is that the shape of the ceiling portion 14a of the lid body 14 is substantially circular. And the radius of curvature is larger. Thereby, for example, the radius of curvature of this portion is set to 1.2R or more with respect to the radius R of the wafer, and the direction of the air flow is smoothly reversed along the ceiling portion 14a. In this example, a workpiece holding plate 50 is integrally provided as a workpiece holding portion for holding the carrier 10 on the upper part of the partition plate 20, and the carrier is not used. On the inner surface of the workpiece holding plate 50, guide grooves 50a for guiding the peripheral edge of the wafer Wf are arranged opposite to each other.

  6 and 7 show a third embodiment of the present invention. The difference of this embodiment from the first embodiment is that one DC brushless motor fan 30 is installed in the central chamber 22a. It is the point arrange | positioned so that it may blow on the lower baseplate part 16 upwards. That is, a support portion for the motor fan 30 is attached to the bottom plate portion 16, and a diffusion plate 52 for equalizing the air to the entire width of the central chamber 22a is disposed between the brushless motor fan 30 and the chemical filter 24.

By comprising in this way, the motor fan is completed by one unit and the whole weight reduction is achieved. That is, when the width W of the holding container 18 is set to 250 mm, the depth D is set to 200 mm, and the height H is set to 380 mm, and 25 pieces of 6-inch wafers are stored, the total weight including the wafer Wf is 6 kg. It can be transported. In this embodiment, the motor fan 30 is operated so that the passing speed of the circulating air having the air volume of 0.1 m ³ / min in the holding container 18 at the center of the gap of the wafer Wf becomes 0.1 m / s. It is set so that it can flow.

  FIG. 8 (front view) and FIG. 9 (side view) show the results of analyzing the flow situation in the third embodiment using a computer. In these drawings, the air flow velocity distribution at the outlet of the motor fan 30 and the air flow lines inside the container body are shown. From these figures, the clean air that has passed through the chemical filter 28 and the ULPA filter 26 woven simultaneously with ion exchange fibers and activated carbon fibers flows uniformly through the gaps in the wafer Wf and circulates without staying in the holding container 18. Can be confirmed.

  Next, FIG. 10 shows the transition of the concentration when operating from a predetermined initial ammonia concentration. The measuring method is the impinger method. From the figure, it can be confirmed that even in a low concentration environment, the ammonia concentration becomes 1 ppb or less after 10 minutes of operation.

  11 and 12 show a fourth embodiment of the present invention. The difference between this embodiment and the third embodiment is that the power supply unit 40 is arranged on the bottom plate portion 16, and the backflow is shown. The prevention chemical filter 32 is disposed at the suction port of the DC brushless motor fan 30, the pocket 53 for storing the dehumidifying agent 54 is provided, and the holding container 18 and the like are structured to be injection-molded, so that mass production is possible. It is possible.

  With this configuration, the structure has a low center of gravity, and the overall size and weight are reduced. That is, when the width W of the holding container 18 is set to 280 mm, the depth D is set to 220 mm, the height H is set to 360 mm, and 25 wafers of 8 inches are accommodated, the total weight including the wafer Wf is 6 kg. Despite this increase in size, the size and weight can be further reduced as compared with the third embodiment.

  Next, FIG. 13 shows the result of measuring the change over time in the relative humidity inside the holding container 18 by storing 100 g of the dehumidifying agent in the clean box shown in the fourth embodiment of the present invention. FIG. 13 shows a comparison between the case where the motor fan 30 is operated continuously and the case where it is stopped. From FIG. 13, it can be confirmed that the relative humidity in the holding container can be reduced to about 25% within a few minutes by operating the motor fan 30.

  The present invention is useful as a clean box used for storing or transporting a workpiece such as a semiconductor wafer, a photomask, or a hard disk in a clean room or the like while maintaining cleanliness.

FIG. 1 is a front sectional view showing a clean box according to a first embodiment of the present invention. 2 is a cross-sectional view taken along line AA in FIG. FIG. 3 is an exploded perspective view for explaining an article constituting the clean box of the embodiment of FIG. FIG. 4 is a longitudinal front view showing a second embodiment of the present invention. 5 is a cross-sectional view taken along line BB in FIG. FIG. 6 is a longitudinal front view showing a third embodiment of the present invention. 7 is a cross-sectional view taken along the line CC of FIG. FIG. 8 is a front view showing a flow analysis result in the third embodiment. FIG. 9 is a side view showing a fluid analysis result in the third embodiment. FIG. 10 is a graph showing changes in ammonia concentration in the third embodiment. FIG. 11 is a longitudinal front view showing a fourth embodiment of the present invention. 12 is a cross-sectional view taken along the line DD of FIG. FIG. 13 is a graph showing the transition of humidity in the fourth embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Carrier 12 Container main body 14 Cover body 14a Ceiling part 16 Bottom plate part 16a Inner surface 16b Upper frame 18 Holding container 20 Partition plate 22a Central chamber 22b Side chamber 24 Carrier support 26 Particle removal filter 28 Chemical filter 30 DC brushless motor fan 32 Chemical for backflow prevention Filter 34 Upper rectifier plate 36 Lower rectifier plate 38 Carrier inlet rectifier plate 40 Power supply unit 40a Mounting slot 44 Support base 50 Workpiece holding plate 50a Guide groove 53 Pocket 54 Dehumidifier

Claims (6)

A holding container composed of a container main body for housing the substrate and a lid that covers the opening of the container in a sealable manner;
A motor fan that forms a circulating flow of airflow in contact with the substrate in the container body;
A particle removal filter and a gaseous impurity capturing filter disposed in a flow path of an airflow flowing toward the substrate;
A dehumidifier disposed in the container body,
A clean box, wherein the holding container is made of a resin mixed with an antistatic agent.   The clean box according to claim 1, further comprising a control unit that controls operation of the motor fan.   The clean box according to claim 1, wherein the airflow flows substantially parallel to a main surface of the substrate.   The clean box according to any one of claims 1 to 3, wherein a filter for preventing a backflow of contaminants from the motor fan is disposed on the downstream side of the substrate holding portion of the circulating flow.   5. The clean box according to claim 1, wherein the dehumidifying agent is provided on the downstream side of the substrate holding part of the circulating flow and on the upstream side of the motor fan.   The clean box according to claim 1, wherein the gaseous impurity trapping filter is a chemical filter.

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