Patent Application
20060288664
1. Field of the Invention
The present invention relates to a product container employed for containing a product such as a semiconductor, a panel for a flat panel display, or an optical disk in a product manufacturing process conducted under a high clean envelopment, and a so-called load port for conducting an open/close operation of the container. In particular, the present invention relates to a purge system for replacing a gas sealed in a so-called front-opening unified pod (FOUP) where the product is used as an object to be contained in processing of wafer of the above product, mainly, a semiconductor wafer that is 300 mm in diameter, and a table used in structuring the purge system.
2. Related Background Art
Up to now, in a process of manufacturing a semiconductor device, an overall factory in which a wafer is subjected to various processing is brought to a clean room state to cope with a demand for high cleaning during the process. However, as the diameter of the wafer increases, there arises a problem in obtaining the high clean envelopment through the above coping in terms of costs or the like. In recent years, means for ensuring a mini environment space that keeps the high cleaning degree with respect to the various processing devices.
In particular, the cleaning degree of the entire factory is not enhanced, but only interiors within the respective processing devices in a manufacturing process and an interior within a storage container (hereinafter referred to as “pod”) during travel between the respective processing devices are kept to the high cleaning degree. The pod is generically named “FOUP” as described above. In this way, a so-called mini environment system that highly cleans only a slight space is applied, to thereby obtain the same effect as that in the case where the entire factory is brought to a clean room state, delete capital investment and maintenance costs, and realize the effective production process.
Hereinafter, a description will be briefly given of a semiconductor processing device that copes with the so-called mini environment system, which is actually employed.
A pod 2 that is a storage vessel of a product to be contained such as a silicon wafer (hereinafter referred to simply as “wafer”) is installed on the load port portion 51. As described above, the interior of the transport chamber 52 is kept to the high cleaning degree in order to process a wafer 1, and a robot arm 54 is also disposed in the interior of the transport chamber 52. The wafer is transported between the interior of the pod 2 and the interior of the processing chamber 59 by the robot arm 54. Various mechanisms for subjecting a wafer surface to processing such as thin film formation or thin film processing are normally included in the processing chamber 59. Those structures are directly irrelevant to the present invention, and therefore their description will be omitted.
The pod 2 includes a box type main body portion 2a having a space for receiving the wafer 1 which is an object to be processed therein, and having an opening portion on any one side, and a cover 4 for tightly closing the opening portion. A rack having a plurality of steps for stacking the wafers 1 in one direction is arranged in the interior of the main body portion 2a. The respective wafers 1 that are mounted on the steps are contained in the interior of the pod 2 at constant intervals. In this example, the direction along which the wafers 1 are stacked is vertical. An opening portion 10 is defined at the load port portion 51 side of the transport chamber 52. The opening portion 10 is disposed at a position that faces the opening portion of the pod 2 when the pod 2 is disposed on the load port portion 51 so as to come close to the opening portion 10. Further, an opener (not shown) is disposed in the vicinity of the opening portion 10 within the transport chamber 52. After the opener removes the cover 4 from the pod 2, the operation of carrying in and out the wafer 1 is conducted by the robot arm 54.
Filter members 11 are disposed in the vicinity of the opening portions of the inlet and outlet ports 7 and 9 at the pod side so as to prevent dusts from entering the interior of the pod 2 through the ports 7 and 9. Further, the inlet port 14 and the outlet port 16 at the table 53 side are connected to substitution air discharge sources (not shown) which are external devices through a check valve (not shown) and a flow meter (not shown) Here, the FOUP as the pod 2 is normally made up of a resin mold product. Therefore, even in the case where a pressure within the pod is slightly different from an external pressure, the FOUP is deformed. For that reason, the above inlet and outlet ports are normally in open states, and those ports are used as breathing ports, and a difference between the internal pressure of the FOUP and the external pressure thereof is eliminated to prevent the deformation of the FOUP.
The above structure is schematically disclosed in, for example, Japanese Patent Application Laid-Open No. 2002-510150 and U.S. Pat. No. 6,164,664. Normally, the wafer 1 that suppresses the adhesion of dusts is taken in the above pod 2 for containing the product therein, and an internal atmosphere is replaced with an inactive gas such as clean nitrogen, to thereby suppress a chemical change such as native oxidation or the occurrence of organic contamination with respect to the wafer surface that is in a contained state. The above replacement operation of the internal atmosphere is conducted through a gas flow path that is formed of the inlet and outlet ports which are disposed in the pod 2 and the table 53, respectively, in a state where the pod 2 is placed on the table 53. Therefore, it is necessary that the gas flow path ensure a magnitude for allowing a sufficient amount of replacement gas or internal atmosphere to flow, and a sufficient air-tightness for preventing the displacement gat or the internal atmosphere from being contaminated. The sealing members 18 are demanded to ensure the sufficient sealing characteristic that satisfies those requirements.
In the case where the pod 2 is placed on the table 53, the inlet port 7 and the outlet port 9 form a completely closed loop as a gas circulating path through the interior of the pod by the sealing members 18. The formation of the closed loop prevents a leakage of gas from the interior of the pod to the exterior thereof, or an entrance of gas into the interior of the pod from the exterior thereof. However, in the case where a pressure balance between the gas inlet side and the gas outlet side is not kept in the above structure, a pressure difference between the interior of the pod 2 and the exterior thereof occurs, thereby leads a fear that the pod 2 is deformed. Further, in the case of a pod that contains a large substrate that is 300 mm or more in diameter, there is a fear that a sealing state between the pod main body 2a and the cover 4 is destabilized, and a so-called leakage occurs from the unstable sealing state.
As a method of preventing the pressure fluctuation from occurring, for example, U.S. Pat. No. 6,164,664 discloses a method of controlling a gas flow rate in the gas outlet path so as to introduce a supply of the gas into the interior of the pod by discharging the gas that exists within the pod. According to the above method, it is possible to suppress a gas outlet rate to some degree or less, and prevent a rapid pressure difference from occurring between the interior and the exterior of the pod. However, according to the method, a time required for purging becomes long all anyhow, and an improvement is further required in the productivity. Further, as the volume of the pod 2 becomes larger, a conductance difference between the inlet and outlet ports and the interior of the pod is larger. As a result, a time lag occurs between the movement of gas at the inlet side and the movement of gas at the outlet side, thereby increasing the conditions under which the pressure fluctuation occurs. In this case, the possibility of deformability of the pod 2 that is made of resin becomes large, and the occurrence of a slight pressure difference greatly contributes to the deformation of the pod 2. Further, the occurrence of a rapid and large pressure difference causes vibration of the wafer 1 that is held in the interior of the pod 2, resulting in a fear that the wafer per se is damaged in an extreme case.
The present invention has been made in view of the above circumstances, and therefore an object of the present invention is to provide a purge system that is capable of preventing a pressure difference from occurring between an interior and an exterior of a pod in the purge operation of the interior of the pod 2, and a table in a load port which is used in structuring the purge system.
In order to solve the above problems, according to the present invention, there is provided a purge system in which a container that receives a product therein is placed on a table, and the interior of the container is purged by a predetermined gas, the purge system including:
a gas inlet port that is disposed on a facing surface of the container with respect to the table and used when supplying the predetermined gas to the interior of the container;
a gas outlet port that is disposed on the facing surface of the container with respect to the table and used when discharging the gas within the container to the exterior of the container;
a table side gas supply port that is disposed on a facing surface of the table with respect to the container and has a gas inlet system that supplies the predetermined gas to the interior of the container in association with the gas inlet port; and
a table side gas outlet port that is disposed on the facing surface of the table with respect to the container, and has a gas outlet system that discharges the gas within the container to the exterior of the container from the interior of the container in association with the gas outlet port, and in which:
the interior of the gas inlet system is closed from the exterior of the gas inlet system; and
the interior of the gas outlet system communicates with the exterior of the gas outlet system through a communication path.
In the above purge system, it is preferable that the gas inlet system form a closed state with respect to the exterior by provision of a member having a sealing action between the gas inlet port and the table side gas inlet port; and
the gas outlet system form the communication path between the gas outlet port and the table side gas outlet port by provision of no member having the sealing action between the gas outlet port and the table side gas outlet port.
Alternatively, it is preferable that the purge system further include a valve shaped member that introduces the gas into the interior of the gas outlet system from the exterior of the container through the communication path when a given pressure difference occurs between an internal pressure of the gas outlet system and an external pressure of the gas outlet system.
Moreover, in order to solve the above problems, according to the present invention, there is provided a purge operation table faces a container that receives a product therein and includes one surface having a gas inlet port which is used when a predetermined gas is supplied to the interior of the container, and a gas outlet port which is used when a gas which exists in the interior of the container is discharged to the exterior, in which the one surface of the container is placed on the table to purge the interior of the container by the predetermined gas, the purge table including:
a table side gas supply port that is disposed on a facing surface of the table with respect to the container and has a gas inlet system that supplies the predetermined gas to the interior of the container in association with the gas inlet port; and
a table side gas outlet port that is disposed on the facing surface of the table with respect to the container, and has a gas outlet system that discharges the gas within the container to the exterior of the container from the interior of the container in association with the gas outlet port, in which:
the interior of the gas inlet system is closed with respect to the exterior of the gas inlet system when the container is placed on the table to form the gas inlet system; and
the content of the gas outlet system which is formed at the same time communicates with the exterior of the gas outlet system through a communication path.
In the above purge operation table, it is preferable that:
the gas inlet system form a closed state with respect to the exterior by provision of a member having a sealing action between the gas inlet port and the table side gas inlet port; and
the gas outlet system form the communication path between the gas outlet port and the table side gas outlet port by provision of no member having the sealing action between the gas outlet port and the table side gas outlet port.
Alternatively, it is preferable that the purge operation table further include a valve shaped member that introduces the gas into the interior of the gas outlet system from the exterior of the container through the communication path when a given pressure difference occurs between an internal pressure of the gas outlet system and an external pressure of the gas outlet system.
According to the present invention, a gas within the pod which is discharged from the outlet port in the pod and the atmosphere that exists around the outlet port are sucked and discharged at the same time by the outlet port in the purge system. As a result, it is possible to suppress a pressure difference from occurring between a inlet side pressure and an outlet side pressure of the gas, and it is possible to suppress a pressure difference between the interior and the exterior of the pod to prevent the pod from being deformed. In other words, in the present invention, in the case where the pressure difference between the interior and the exterior of the pod starts occurring, the atmosphere around the outlet port is supplied to the outlet port as a buffer. As a result, a large fluctuation within the pod due to the gas discharge is suppressed. Further, it is possible to purge the interior of the pod at a high rate after the pressure fluctuation has been suppressed, to thereby obtain the effect that a time required for purging is shortened.
In addition, it is more preferable to provide a valve shaped member having a so-called check operation that enables atmosphere introduction only when a given pressure difference occurs in a communication path that is a supply path in the case of supplying the atmosphere around the outlet port. The arrangement of the valve shaped member reduces the possibility that the atmosphere under which the moisture content is not managed in a normal state enters the interior of the pod, thereby making it possible to preferably maintain the environment of the interior of the pod.
The above and other objects, features, and advantages of the invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings.
Now, a description will be given of embodiments of the present invention with reference to the accompanying drawings.
Referring to
In this embodiment, the purge operation of the gas within the pod 2 is conducted by a low voltage source (not shown) which is disposed downstream of the table side outlet port and generates a negative pressure. Further, the conductance of the inlet system is made substantially identical with the conductance of the outlet system in the case where the sealing member 18 is interposed therebetween. Alternatively, it is also possible that a high pressure source that generates a positive pressure is disposed upstream of the table side inlet port, and the gas in the interior of the pod 2 is extruded by the gas that is supplied from the high voltage source to conduct the purge operation. In this case, for example, it is preferable that the conductance of the outlet system be set to be larger than the conductance of the inlet system (more specifically, there is proposed a modification such that the inner diameter of the outlet port is made larger), and the outlet resistance at the time of extruding the gas within the pod be reduced. However, in order to shorten a time required for purging, it is preferable to use both of the high voltage source and the low voltage source.
Subsequently, a description will be given of a modified example of the above-described embodiment with reference to
The atmosphere that exists around the outlet port is different from an inactive gas that is positively supplied to the interior of the pod 2, for example, dry nitrogen, and is not controlled in the moisture content, and is not also controlled in the contamination material of the organic system. Therefore, it is preferable to prevent the above atmosphere from entering the interior of the pod 2. Therefore, for example, as shown in
The valve shaped member 25 is deformed and makes the external space communicate with the interior of the outlet system in the case where the interior of the outlet system generates a pressure difference by a given pressure with respect to the external space. Because the valve shaped member 25 is disposed in the communication space 21 or the communication path 23, it is possible to reduce the risk that the atmosphere enters the interior of the pod 2 from the external space, and to obtain the effects of the present invention. In this embodiment, a film member that is bent by application of a pressure of some degree is disposed around the table side discharge port on the table 53 so as to be used as the valve shaped member 25. However, the configuration of the member is not limited to the above configuration. For example, it is possible that a normal so-called check valve is disposed in the communication path 23 according to the embodiment shown in
Now, an embodiment of the present invention will be described below.
A pod 2 includes recesses 5, an inlet port 7, and an outlet port 9 at a bottom surface thereof. Further, the surface of a table 53 on which the pod 2 is placed is equipped with positioning pins 12 that are fitted into the recesses 5 to regulate the placement position of the pod 2, a table side inlet port 14 that constitutes the inlet system in association with the inlet port 7 at the pod 2 side, and a table side outlet port 16 that constitutes the outlet system in association with the outlet port 9 at the pod 2 side. Further, a toric sealing member 18 is disposed between the inlet port 7 and the table side inlet port 14 facing each other to enhance the air-tightness with respect to the exterior of the pod 2 of the inlet system. No sealing member 18 is disposed between the outlet port 9 and the table side outlet port 16, and a communication space 21 having an interval that substantially corresponds to the sealing member 18 is formed between those ports when the positional relationship between the pod 2 and the table 53 is determined according to the recesses 5, the positioning pins 12, the inlet system, and the like.
Filter members 11 are disposed in the vicinity of the opening portions of the inlet and outlet ports 7 and 9 at the pod side so as to prevent dusts and the like from entering the interior of the pod 2 through the ports. Further, an upstream side of the table side inlet port 14 and a downstream side of the table side outlet port 16 in the gas flow are connected to a replacement gas inlet source and a replacement gas outlet source (not shown) which are external devices through a check valve and a flow meter (not shown), respectively. Further, in this embodiment, a flow controller 27 is disposed upstream of the table side inlet port 14 so as to control the flow rate of gas that is supplied to the interior of the pod 2.
Hereinafter, a description will be given of the purge operation and the like in an FOUP system to which the present invention is applied with reference to the drawings. First, the semiconductor wafer 1 is contained in the interior of the pod 2, and the pod 2 having the interior tightly closed by a cover 4 is transported above the table 53. The pod 2 is mounted on the table 53 in a state where the positioning pins 12 that project from the table 53 are substantially fitted into the recesses 5 that are disposed on the lower portion of the pod 2. In this state, the inlet port 7 at the pod side is abutted against the table side inlet port 14 that is disposed on the table 53 through the sealing member 18. Further, the outlet port 9 and the table side outlet port 16 face each other to form the communication space 21 therebetween.
In this example, the inlet system and the outlet system are connected to the replacement gas supply source and the replacement gas discharge source, respectively. In this situation, the flow rate of gas inlet for purging is set by the flow controller 27 in advance. In this situation, the gas for purging is sucked to the interior of the pod 2, and the gas within the pod 2 is discharged. When the magnitude of the replacement gas discharge source is set to be large, the sufficiently large gas discharge is conducted as compared with the gas suction, to thereby suppress the step-up of the internal pressure within the pod 2 due to the gas suction. Further, in the gas that is excessively discharged, the atmosphere is replenished through the communication space 21 to prevent the internal pressure of the interior of the pod 2 from being reduced. While this state is maintained, the purge operation within the pod 2 is conducted. In the purge operation, the replacement gas is circulated in the stated order of the table side inlet port 14, the sealing member 20, the inlet port 7 at the pod 2 side, the filter 11, the interior of the pod 2, the filter 11, the outlet port 9 at the pod 2 side, and the table side outlet port 16, to thereby replace the atmosphere within the pod 2.
In this embodiment, there are the table 53 in which the inlet port and the outlet port are formed by one system, respectively, and the pod 2 corresponding to the table 53. However, the configuration to which the present invention is applicable is not limited to the above structure, but it is preferable that the numbers of inlet ports and outlet ports be appropriately increased or decreased taking into consideration the demanded gas replacement speed, the capacity of the pod 2, and the like.
In the above first and second embodiments, the present system is applied to the FOUP, but the embodiment of the present invention is not limited to the above system. To be more specific, the system according to the present invention can be applied to a system having a container that receives a plurality of objects to be held (products) therein, and a transport chamber that transports the object to be held from the container to a device that processes the object to be held, in which the atmosphere within the container is purged.
As many apparently widely different embodiments of the present invention can be made without departing from the spirit and scope thereof, it is to be understood that the invention is not limited to the specific embodiments thereof except as defined in the appended claims.
This application claims priority from Japanese Patent Application No. 2005-184788 filed Jun. 24, 2005, which is hereby incorporated by reference herein.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2005-184788 | Jun 2005 | JP | national |
