JP2002170876A - Substrate transport container - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a substrate transport container which efficiently prevents a pollution to the contained substrates to be stored or transported from outer atmosphere, also which is made possible the atmosphere to be efficiently substituted in a short time by introducing a dry air or the like into the container. SOLUTION: A substrate transport container 10 comprises a container main body 12 in which substrates to be stored or transported are contained, and a door 14 which can tightly close the main body 12. A suction port 30 and air outlet 32 for communication or substitution of the air inside of the substrate transport container 10 with clean air, a duct 38 joined to the suction port 32 and extended into the container 10, and a straightening vane 40 disposed to a face directed inward of the container 10 of the duct 38 are provided for the substrate transport container 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a substrate transport container suitable for storing or transporting an object to be processed, such as a semiconductor wafer, a photomask or a hard disk, in an atmosphere having a very high degree of cleanliness.

[0002]

2. Description of the Related Art For example, when a semiconductor factory or a substrate such as a photomask is transported and stored in a semiconductor factory during a manufacturing process, a minute amount of dust or gaseous impurities present in the atmospheric air is transferred to an object such as a semiconductor wafer. Adhesion leads to a decrease in product yield, and this tendency becomes more pronounced as the degree of integration increases. Also, with the advent of the magneto-resistive head, the recording density has been further accelerated with the advent of the magnetic disk, and a high cleanliness is required not only for dust but also for gaseous impurities. Further, from the viewpoint of reducing the corrosion of the semiconductor wafer, a simple means for keeping the humidity of the atmosphere in which the substrate is stored low is also required.

[0003] In order to create a clean space for accommodating a substrate in such a case of transport and storage, a motor fan and a HEPA are used.
(High efficiency particle
air) filter and ULPA (ultra low
A substrate transport container or the like equipped with a penetration air) filter has been developed. Also, for example, as a method of locally cleaning the periphery of a semiconductor wafer, a method in which the inside of a substrate transfer container containing a semiconductor wafer is replaced with high-purity nitrogen to maintain cleanness and suppress the growth of a native oxide film. There is.

However, the HEPA filter and U
With an LPA filter, particulate contaminants can be removed, but trace amounts of organic or inorganic gases cannot be removed. In addition, if a large amount of circulating air flows into a portion that does not directly contribute to the cleaning of the object to be processed, or if there is a stagnant portion in the substrate transport container, it is not possible to improve the ventilation efficiency in the substrate transport container, and the substrate is cleaned. The effect of preventing contamination of the object to be treated by the air that has been generated is reduced. Further, the method of replacing with nitrogen has a problem that impurities generated from the semiconductor wafer itself coated with a resist or the like cannot be removed.

[0005] That is, for example, in storing semiconductor wafers, molecular contaminants have become a problem due to miniaturization of semiconductor elements. For example, when an organic component such as a resist adheres to the inner wall of the substrate container from the semiconductor wafer itself coated with the resist or the like, the portion becomes a source of contamination, and the growth of a non-uniform natural oxide film and pattern defects due to the chemically amplified resist become apparent. There is a problem. In addition, a variety of materials are used for film formation by chemical vapor deposition and diversification of wiring materials. If these materials adhere to the inner wall of the container, they also become a source of contamination of semiconductor wafers to be maintained in a clean environment.

On the other hand, among semiconductor elements, DRAM is a small-volume, mass-produced product, but it is predicted that the proportion of system LSI will increase in the future, and semiconductor production tends to shift to multi-variety, small-volume production. . These semiconductor wafer processing lots require high-speed transfer between processes and tend to have a random storage time until the next processing. For this reason, these semiconductor wafers are transported and
As a substrate transport container to be stored, it is required that semiconductor wafers are always maintained in a clean environment in response to diversification of semiconductor manufacturing processes in which various contaminants are generated as described above and process waiting time between processes. ing.

[0007]

SUMMARY OF THE INVENTION In view of the above problems, the present invention efficiently prevents contamination of a housed storage or transfer target substrate from an external atmosphere, and introduces a dry gas or the like into a container. An object of the present invention is to provide a substrate transfer container capable of efficiently replacing an atmosphere in a short time.

[0008]

According to the first aspect of the present invention,
In a substrate transport container including a container main body for storing a substrate to be stored or transported therein and a door that can be closed with respect to the container main body, the inside of the substrate transport container is circulated or replaced with a clean gas. An air supply port and an air exhaust port for performing, a duct connected to the air supply port and extending into the container,
A flow straightening plate disposed on a surface of the duct facing the inside of the container.

By adjusting the aperture ratio of the current plate so that the gas flow in the container becomes uniform, a large number of semiconductors housed in the container from the air supply port via the duct provided with the current plate. A clean gas can be uniformly supplied between substrates to be processed such as wafers. Accordingly, the efficiency of replacement of the clean gas in the container is improved, and the clean gas can be replaced in a short time. In addition, when storing a plurality of semiconductor wafers while flowing a clean gas, for example, the clean gas flows uniformly between a large number of semiconductor wafers, thereby efficiently contacting the surface of the semiconductor wafer with the clean gas. It can be stored while being stored.

The invention according to claim 2 is the substrate transport container according to claim 1, further comprising a filter for removing particles and a filter for removing gaseous impurities near the air supply port. Thereby, not only the particulate contaminants contained in the clean gas flowing into the container but also the gaseous contaminants can be removed. Therefore, it is possible to prevent contamination by a substance contained in the gas introduced from the outside into the substrate to be stored and transported.

According to a third aspect of the present invention, there is provided the substrate transfer container according to the first aspect, wherein the air supply port and the exhaust port are provided with a backflow prevention mechanism. Thus, only when the gas pressure on the gas pipe side of the supply port becomes higher than the gas pressure inside the container, a clean gas is supplied into the container, and the gas pressure inside the container is higher than the gas pressure outside the exhaust port. When the pressure rises, clean gas is discharged from the container. Therefore, the backflow of the clean gas to be replaced or circulated is prevented.

According to a fourth aspect of the present invention, there is provided a substrate transport container comprising a container body for storing a substrate to be stored or transported therein, and a door which can be closed with respect to the container body. A substrate transport container characterized in that a main material constituting the main body is made of a polymer material having a water absorption of 0.1% or less or a moisture-impermeable material. Accordingly, when the replacement of the clean gas in the container is stopped, the amount of moisture diffusing from the inner wall surface of the container into the container is reduced, and the humidity in the container can be kept low. Therefore, it is possible to prevent a defect or the like due to contamination of the substrate to be processed due to moisture.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 and FIG. 2 show a substrate transport container according to an embodiment of the present invention. The substrate transfer container is for carrying, for example, a semiconductor wafer (substrate to be processed) W having a diameter of about 200 mm in a cassette in a state of being housed in a cassette, and carrying and storing the wafer. The substrate transport container 10 includes a rectangular cylindrical container main body 12 having an opening at the bottom for taking in and out a substrate to be processed stored in a cassette, and a door 14 for closing the opening. The door 14 is connected to an automatic opening / closing device 18 for the substrate loading / unloading door provided on the device 16 side, so that the opening on the bottom surface of the container body 10 can be opened and closed.

A cassette 20 is mounted on the door 14,
Many semiconductor wafers W are stored in this. Door 1
4 is provided with a latch mechanism, and a substrate loading / unloading door automatic opening / closing device 18 releases a latch provided on the door 14 and lowers the elevating mechanism 22 so that the cassette 2 together with the door 14
0 can be taken out from the container body 12 and the semiconductor wafer W mounted on the cassette 20 can be taken out from the cassette 20. When the semiconductor wafers are stored in the container 12, the cassette 20 on which the semiconductor wafers W are mounted is placed on the door 14, the elevating mechanism 18 is raised, the cassette 20 is inserted into the container body 12, and the substrate is unloaded. The door 14 is fixed to the container body 12 by locking the latch mechanism provided on the door 14 by the automatic door opening / closing device 18. A gasket or the like is arranged at a contact portion between the door 14 and the container main body 12, so that the inside of the container 10 can be kept airtight.

A container 10 containing a processed semiconductor wafer
For example, when the container 10 is separated from the load port of the apparatus 16 and transported, the replacement with the clean gas inside the container 10 is performed immediately before the separation. As this clean gas, an inert gas, dry air, or moist air is used. In such a case, in order to reduce the replacement time of the inside of the container by the clean gas, it is important to increase the flow rate and the replacement efficiency. Therefore, the container 10 has a configuration in which the area of the outlet for the clean gas is increased and the clean gas flows uniformly in the container.

The clean gas replacement is usually carried out on an automatic door opening / closing device attached to a semiconductor manufacturing apparatus, before loading a wafer into the apparatus or after storing a processed wafer in a container. As other periods, for example, AGV (Automated Guided Vehicle)
le), etc., and may be carried out at the time of transport / storage, such as a substrate transport device, a storage, or a storage shelf. When performing gas replacement on an automatic door opening and closing device, it is important to perform high-speed replacement within a container at a high flow rate, for example, 10 to 40 L / min in a short time. Therefore, the container 10 has a configuration in which the area of the outlet for the clean gas is increased, and the clean gas flows uniformly in the container. On the other hand, when storing in a storage, for example, 0.5 to
What is necessary is just to replace slowly at a low flow rate of about 5 L / min.
As this clean gas, high-purity nitrogen gas, inert gas, or dry air is used.
It is possible to use moist air of a high degree of purity. The method of replacing the gas is, for example, to continuously exhaust the gas from the exhaust port while continuously injecting the gas to the air supply port, or to temporarily stop after injecting a constant flow rate of gas from the air supply port, and to stop the gas from the exhaust port. There is a method of repeating the operation of exhausting at a flow rate, or a method of intermittently exhausting the gas from the exhaust port while keeping the gas flowing through the air supply port. The replacement is preferably performed by a method in which the air originally trapped in the container and the clean gas to be injected can be efficiently mixed and replaced. Therefore, rather than simply flowing the clean gas continuously and exhausting continuously, supply and exhaust are intermittently repeated. Thus, a method in which the exhaust is continuously performed is preferable.

FIGS. 3A, 3B, 3C and 3D show details of the structure of the door. (A) shows the lower surface of the door 14, in which an air supply port 30 and an exhaust port 32 for circulating or replacing the inside of the container 10 with clean gas are arranged. Further, on the lower surface of the door 14, there is provided a positioning hole 34 for engaging with the substrate loading / unloading door automatic opening / closing device 18, and by engaging with a pin provided on the substrate loading / unloading door automatic opening / closing device 18, the door 14 is unloaded. It is fixed to the entrance door automatic opening / closing device 18. The door latch 36 rotates the door latch 36 to rotate the door 14.
The door 14 is locked by locking a latch mechanism provided in the door.
Is fixed to the container body 12 and the door 14 can be opened from the container body 12 by unlocking. Supply / exhaust port 3
The dimensions and arrangement of the 0, 32, positioning hole 34, door latch 36, etc. are unified according to Semi standard or the like.

The door 14 is provided with the semiconductor wafer W in the container 10.
A duct 38 is arranged which extends to near the top height at which is disposed. The duct 38 has a front end 38a closed, and a flow straightening plate 40 having a large number of openings shown in FIG. The current plate 40 has a number of openings as shown in FIG.
This opening ratio is configured such that the opening ratio is large on the air supply port side and becomes smaller toward the distal end portion of the duct 38. The clean gas supplied from the air supply port 30 provided on the bottom surface of the door 14 by the duct 38 and the current plate 40 is
Since the gas flow rises inside and the tip is closed, the gas flow can be turned 90 ° and blown out of the current plate (see FIGS. 1 and 2). If the opening ratio of the current plate 40 is made uniform, the upper end of the duct 38 is closed, so that the supply pressure becomes higher toward the upper part of the duct, and the blowing amount increases. Therefore, by increasing the opening ratio at the lower part of the duct 38 and decreasing the opening ratio toward the upper part of the duct, a uniform blowing amount can be obtained along the height direction of the duct.

By providing such a duct 38 and a flow straightening plate 40, it is possible to increase the area for blowing clean gas, thereby reducing the wind speed at the passage surface and increasing the flow rate of gas and the efficiency of replacing gas in the container. Can be raised. Thereby, the replacement time inside the container 10 of the clean gas can be reduced.

FIG. 5 is a diagram showing the replacement characteristics of the substrate transfer container of the present invention by a dry gas. That is, it is a graph showing a change in relative humidity upon replacement with a dry gas. A black triangle mark in the figure is a case where a normal polycarbonate container is used, the flow rate is 5 L / min, and a cross mark in the figure is shown.
The mark indicates the case where the flow rate is 10 L / min. As shown in the figure, it takes about 15 minutes to reach the lower limit humidity,
There is almost no difference due to the flow rate. On the other hand, a white circle indicates a container using a polymer material having a water absorption of 0.1% or less according to the present invention, and similarly shows a case where the flow rate of the dry gas is 10 L / min, and about 5 minutes. To reach the lower humidity limit. This indicates that the replacement efficiency of the drying gas is high, and the replacement efficiency is improved by supplying the drying gas from the duct 38 into the container through the flow straightening plate 40 so as to form a uniform flow. Which indicates that.

In this embodiment, an example is shown in which a punching plate having a large number of circular openings is used as a flow regulating plate. You may make it adjust ventilation resistance so that it may be obtained. Further, in this embodiment, the example in which the duct including the current plate is provided in the door is shown, but the duct may be fixed to the container body.

Next, a check valve provided in the air supply port will be described with reference to FIG.
This will be described with reference to FIG. The check valve 42 is fixed to a fixing portion 46 by a spring 44. An O-ring seal 48 is provided at a contact portion between the fixing portion 46 and the check valve 42. Therefore, when the pressure on the downstream side A of the check valve 42 is higher than the pressure on the upstream side B, the spring 44 expands and the check valve 42 is closed as shown in FIG. When the pressure on the downstream side A of the check valve 42 is lower than the pressure on the upstream side B, the spring 44 contracts and the check valve 42 is opened as shown in FIG.

Next, the connection between the air supply port and the duct will be described with reference to FIG. The air supply port 32 is provided with the above-described check valve 42. The filter 50 includes a filter for trapping particulate contaminants such as ULPA filter material and a filter 54 for trapping gaseous impurities. Various filters are known as the particulate contaminant trapping filter 52, but an ULPA filter using a fluororesin that is hydrophobic and emits no impurities is preferable. Gaseous impurity trapping filter 54
Is activated carbon, impregnated activated carbon, activated carbon fiber, zeolite,
These can be used alone or in combination of silica gel, ion-exchange nonwoven fabric or fiber. In this embodiment, an activated carbon 54a and an ion-exchange nonwoven fabric 54b sandwiching the activated carbon 54a are used.
It is preferable to use a material that does not generate dust for the filter that captures these gaseous impurities in order to reduce the load on the filter for capturing particulate contaminants. Each filter has an average surface wind speed of 0.1 m / s or less, preferably 0.05 m / s or less.
m / s, it is necessary to be able to reliably capture the contaminants contained in the outside air flowing from the connected gas pipe or purge pipe.

When storing semiconductor wafers in a container, the most difficult is the problem of humidity. In the substrate transfer container 10 of this embodiment, the material of the container body 12 and the door 14 is made of a polymer material having a water absorption of 0.1% or less or a moisture-impermeable material. These materials are ASTM (Ame
rican Society for Testing
and Materials) D570 standard. The water absorption of general materials used for transfer / storage containers for semiconductor wafers and the like is as follows: PC (polycarbonate) 0.2%, PBT (polybutylene terephthalate) 0.08%, PEEK (polyether ether ketone) 0.14%, PEI (polyetherimide)
0.25% and PP (polypropylene) 0.03%.

The preferred material of the container 10 is a water absorption of 0.1% or less, which corresponds to PE (polyetherimide) <0.01%, PP
(Polypropylene) 0.03%, PBT (polybutylene terephthalate) 0.06 to 0.08%, PPS (polyphenylene sulfide) 0.02%, PTFE <0.0
1%, PC (polycarbonate with 20% carbon)
0.1%, and PBT (polybutylene terephthalate with 20% carbon added) 0.05%. Particularly preferred as the container material is a material having low water absorption, good chemical resistance, high stability at high temperature, and low molding shrinkage, such as PPS (polyphenylene sulfide) and carbon-added polybutylene. Terephthalate (PB
T), carbon-added polycarbonates are particularly preferred.

Further, when the humidity is low, the wafer is easily charged. Therefore, at least the wafer supporting member in contact with the wafer and the door which is grounded from the wafer supporting member to the lower part of the container are preferably made of a conductive material to which carbon or the like is added. Furthermore,
Since the ion-exchange nonwoven fabric and the activated carbon used as the gaseous impurity trapping element adsorb water in a state immediately after the production, it is preferable to use them after dehydration treatment in advance.

When the inside of the container is replaced with a dry gas, that is, dry air or an inert gas containing no moisture, immediately after the replacement, the humidity decreases to a limit humidity of approximately 0%. However, if the supply of the dry gas is stopped and left in this state, the moisture held by the polymer material on the inner wall surface of the container diffuses into the container due to the humidity gradient. Therefore, the humidity inside the container replaced by the dry gas increases with time. FIG. 8 shows an example of this, where approximately 0% after replacement with dry gas.
Shows that the relative humidity increases to 30% or more after several hours when a conventional commercially available PC (polycarbonate) container is used. Water absorption of the embodiment of the present invention 0.0
By using 2% polyphenylene sulfide (PPS), the relative humidity of about 0% immediately after replacement with the dry gas remains at about 12% even after several hours or more, and a remarkable effect of suppressing the increase in humidity is confirmed. Was. It is apparent that this can prevent the humidity in the container from increasing during storage and transportation. It is known that the growth of a natural oxide film has an inhibitory effect when stored in a dark place. For this reason, it is preferable to use a light-blocking material rather than a light-transmitting material as the material forming the container body.

FIG. 5 is a diagram showing the replacement characteristics of the substrate transfer container of the present invention by a dry gas. That is, it is a graph showing a change in relative humidity upon replacement with a dry gas. A black triangle mark in the figure is a case where a normal polycarbonate container is used, the flow rate is 5 L / min, and a cross mark in the figure is shown.
The mark indicates the case where the flow rate is 10 L / min. As shown in the figure, it takes about 15 minutes to reach the lower limit humidity,
There is almost no difference due to the flow rate. On the other hand, a white circle indicates a container using a polymer material having a water absorption of 0.1% or less according to the present invention, and similarly shows a case where the flow rate of the dry gas is 10 L / min, and about 5 minutes. To reach the lower humidity limit. This indicates that the replacement efficiency of the drying gas is high, and the replacement efficiency is improved by supplying the drying gas from the duct 38 into the container through the flow straightening plate 40 so as to form a uniform flow. Which indicates that.

In the above-described embodiment, an example has been described in which polyphenylene sulfide is used as the material of the container, and the drying gas is uniformly flowed from the flow straightening plate whose aperture ratio is adjusted through a duct. Of course, various modifications can be made without departing from the scope of the present invention.

Next, a second embodiment of the present invention will be described with reference to FIGS. The embodiment of the present invention relates to a FOUP (Front Open) for a 300 mm wafer.
This is an example in which the present invention is applied to a sing unified pod. The substrate transfer container includes a container body 12, a door 14 disposed on the front surface of the container, a bottom plate 58 having a kinematic coupling for receiving a positioning pin, and the like, and a plurality of semiconductor wafers W arranged inside the container body. A duct 3 having a wafer supporting member 56 for supporting, a gas supply port 30 and a gas exhaust port 32 attached to the container body 12, and a perforated plate 40 provided at a gas blow-out port on the downstream side of the gas supply port 32;
8. The FOUP is provided with positioning pins and various identification holes at the bottom of the pod in accordance with the SEMI standard. Therefore, the air supply / exhaust ports are arranged at lower left and right sides of the door so as not to interfere with them. As in the first embodiment of the present invention, a check valve 42 and a filter 52 are built in the air supply / exhaust port. After the gas in the container is seated at a predetermined position such as a gas replacement device, a door opener, a transfer device, and a storage, when an inert gas or the like is supplied from an air supply port, impurities are removed by the filter 54, A flow from the perforated plate 40 toward the door is formed through the duct 38. The gas after passing the semiconductor wafer W is exhausted from the exhaust port 32, so that the gas inside the container can be efficiently replaced.

[0032]

As described above, according to the present invention, when flowing or replacing the inside of the substrate transfer container with a clean gas,
By allowing the clean gas to flow uniformly from the current plate through the duct into the container, efficient replacement can be performed without causing gas to stay in the container. As a result, the replacement time with a clean gas can be reduced, and the efficiency of production in a semiconductor factory or the like can be improved. Further, since the clean gas flows uniformly in the container, fresh clean gas can be uniformly supplied to a large number of semiconductor wafers and the like stored in the container to keep them clean. In addition, by providing a filter having a gaseous impurity trapping element and a check valve, it is possible to prevent contamination of a semiconductor wafer or the like stored in a container. Furthermore, by using a polymer material or a moisture-impermeable material having a water absorption of 0.1% or less as a main material constituting the container, it is possible to prevent an increase in relative humidity due to diffusion of moisture from the inner wall surface of the container.

In general, according to the present invention, there is provided a substrate transporting container capable of removing gaseous contaminants, replacing a dry gas or the like in a short time, and preventing the humidity in the container from increasing. Therefore, it is useful when used in a method of manufacturing a semiconductor device or the like such as a high-mix low-volume production.

[Brief description of the drawings]

FIG. 1 is an elevation view of a substrate transport container according to an embodiment of the present invention.

FIG. 2 is a plan view of the substrate transport container shown in FIG.

FIG. 3 shows a structure of a door of the substrate transport container shown in FIG.
5A is a plan view of a lower surface, FIG. 5B is a plan view of an X arrow, FIG. 5C is a plan view of an upper surface, and FIG.

FIG. 4 is a view showing a structure order of a current plate.

FIG. 5 is a graph showing an increase in relative humidity in the container after the supply of the dry gas is stopped, comparing the container of the present invention with the container of the conventional example.

FIG. 6 is a diagram schematically showing the structure of a check valve;
(A) shows a closed state, (b) shows an open state.

FIG. 7 is a diagram showing an example of a connection structure between an air supply port and a duct.

FIG. 8 is a graph showing the replacement characteristics of the inside of the container with the dry gas, comparing the container of the present invention with the container of the conventional example.

FIG. 9 is a side view of a substrate transport container according to a second embodiment of the present invention.

FIG. 10 is a bottom view of a substrate transport container according to a second embodiment of the present invention.

FIG. 11 is a sectional view taken along line AA of FIG. 9;

FIG. 12 is a sectional view taken along the line BB of FIG. 11;

FIG. 13 is a sectional view taken along the line CC of FIG. 11;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Substrate carrying container 12 Container main body 14 Door 20 Cassette 38 Duct 40 Rectifier plate 42 Check valve 52 Filter

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3E067 AA11 AB41 AC03 BA05A BB14A BC06A CA04 CA05 FA01 FC01 GA19 3E096 AA06 BA16 BB04 CA02 CB03 DA25 DA30 DB06 DC02 EA02X FA03 FA22 GA03 5F031 CA02 CA05 CA07 DA09 EA02 EA14 EA14

Claims (4)

[Claims] 1. A substrate transport container comprising a container body for storing substrates to be stored or transported therein and a door which can be closed with respect to the container body, wherein the inside of the substrate transport container is clean. An air supply port and an air exhaust port for flowing or replacing with gas, a duct connected to the air supply port and extending into the container, and a rectifying plate arranged on a surface of the duct facing the inside of the container are provided. A substrate transport container characterized by the above-mentioned. 2. The substrate transport container according to claim 1, further comprising a filter for removing particles and a filter for removing gaseous impurities near the air supply port. 3. The substrate transport container according to claim 1, wherein a backflow prevention mechanism is provided at the air supply port and the exhaust port. 4. A main material constituting the container main body in a substrate transport container including a container main body for storing a substrate to be stored or transported therein and a door that can be closed with respect to the container main body. Characterized by comprising a polymer material having a water absorption of 0.1% or less or a moisture-impermeable material.