DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0064] An embodiment of the present invention will now be described with reference to the accompanying drawings.

[0065] FIG. 1 schematically shows a local clean space system of a semiconductor manufacture apparatus including a clean box according to a first embodiment of the present invention.

[0066] In FIG. 1 , the semiconductor wafer processing apparatus 10 is composed of an apparatus body 30 and a load port 20 for loading a semiconductor wafer within a clean box 40 into the processing device. An interface between the apparatus body 30 and the load port 20 is designated by a line A in FIG. 1 . Usually, the load port 20 is formed as a discrete device that is detachably mounted on the apparatus body 30 . However, the load port may be formed integrally with the apparatus body. The apparatus body 30 is in communication with the load port through an opening 37 formed at a portion indicated by a dotted line on the line A of FIG. 1 for sending and receiving the semiconductor wafer between the load port and the apparatus body through the opening 37 .

[0067] The space within the apparatus body 30 and the space of the load port 20 are in communication with each other through the above-described opening 37 so that the overall interior including both constitutes the local clean space. In order to keep the space clean, a fan intake blower device 32 having a filter is provided at an upper portion of the semiconductor wafer processing apparatus 10 . A downstream air flow is generated within the apparatus by the fan intake blower device 32 to thereby keep the space within the semiconductor wafer processing apparatus 10 clean. The downstream air flow is discharged from the bottom of the apparatus to the outside.

[0068] In FIG. 1 , the clean box 40 in accordance with the present invention is set on a table 21 of a top surface of the load port 20 . The clean box 40 is a sealed type container composed of a box-shaped clean box body 41 that opens at its bottom and a lid 42 for covering the opening of the bottom of the body. As will be described in more detail later, when the clean box 40 is laid on the table 21 of the load port 20 and the wafer W within the clean box 40 is entered and removed, the interface between the clean box body 41 and the table 21 is sealed by a vacuum suction using the annular groove formed in the table 21 to thereby maintain the clean space against the outside.

[0069] The clean box 40 is a container to be used for transfer of wafer among different devices and temporary deposit of the wafer. The clean box 40 has a carrier 43 fixed to the lid 42 . The carrier 43 is a rack type structure for receiving a plurality of wafers in parallel and at an equal interval.

[0070] The clean box 40 is transferred by a transfer means such as an overhead transfer (OHT) system within the factory and is set on the table 21 of the load port 20 . In some case, the transfer of the clean box may be manually performed directly by the operator.

[0071] The clean box 40 will now be described in more detail with reference to FIGS. 2A and 2B and FIG. 3 . FIGS. 2A and 2B are both side elevational views showing, partly in cross-section, the clean box 40 mounted on the load port 20 and the upper portion of a gas replacement unit 50 of the load port 20 and FIG. 3 is a top plan view showing the clean box 40 .

[0072] The clean box body 41 is a container having a substantially square shape. A two stage flanged portion, i.e., a first flanged portion 41 a and a second flanged portion 41 b are provided around the periphery of the clean box body 41 . A groove 46 is provided on that peripheral portion of the top surface of the lid 42 of the clean box 40 which confronts the first flanged portion 41 a of the clean box body 41 . The groove 46 is an annular groove 46 formed so as to surround the peripheral portion of the lid 42 confronting the first flanged portion 41 a of the clean box 40 . O-rings for sealing the annular groove is also mounted on the inside and outside of the annular groove 46 on the lid 42 so as to surround the peripheral portion of the lid also in annular shapes in a well known manner.

[0073] In the clean box 40 according to the present invention, this annular groove 46 is vacuum exhausted to thereby air-tightly seal the interface between the clean box body 41 and the lid 42 by the vacuum suction. Namely, the seal force may be insured by the differential pressure between the outside atmospheric pressure and the vacuum pressure within the annular groove 46 . The vacuum exhaust of the annular groove 46 is performed through a vacuum port 57 (see FIG. 3 ) that is an intake/exhaust port provided on the side surface of the clean box body 41 . The vacuum exhaust will be described later in detail.

[0074] Note that in the subject specification, for the sake of explanation, the terms, “vacuum exhaust”, “vacuum suction” or simply “vacuum” are used but these terms, of course, do not mean a complete vacuum but a condition that the pressure is low relative to the atmospheric pressure.

[0075] Gas ports 55 and 56 for replacing the gas in the interior of the box by the non-oxidizing gas (nitrogen gas, inert gas or the like) are provided and juxtaposed at the same level on the side surface of the box body 41 . One of them is a gas intake port 55 for introducing the gas and the other is an exhaust port 56 for discharging the gas.

[0076] The above-described clean box 40 may lay the article to be transferred such as a semiconductor wafer W or the like on the carrier 43 and transfer and store the article while sealing the non-oxidizing clean gas such as nitrogen in a sealed condition within the clean box by the suction of the annular groove 46 .

[0077] In the case where the clean box 40 is set on the load port 20 , the clean box 40 is positioned so that the lid 42 of the clean box 40 and the load port 20 are aligned with each other. The elevator 22 is a part of a mechanism 23 for opening/closing the lid of the clean box 40 and positioned at its top. The elevator 22 is a table that may ascend and descend together with the lid opening/closing mechanism 23 . A mechanism (not shown) for effecting the vacuum suck of the lid 42 of the clean box 40 is provided on the top surface of the elevator 22 . As will be described later, the lid 42 is opened downwardly, the carrier provided on the lid 42 is introduced into the load port 20 and the wafer laid on the carrier 43 is moved into the semiconductor processing device body. The transfer will be described later in more detail.

[0078] A seal groove 26 is provided at a position confronting the second flanged portion 41 b of the clean box 40 located at a predetermined position on the top surface of the load port table 21 . The seal groove 26 surrounds the elevator 22 in an annular shape. The O-rings 25 are mounted on both sides of the seal groove 26 for maintaining the seal property of the seal groove 26 . The seal groove 26 is connected to a exhaust means (not shown). The seal groove 26 is vacuum exhausted to seal the interface between the load port table 21 and the clean box body 41 (second flanged portion 41 b ) when the clean box 40 is set on the load port table 22 . The system including the interior of the clean box 40 and the interior of the semiconductor wafer processing 10 together is sealed against the outside by the seal with the seal groove 26 , so that the system may be kept in the local clean space.

[0079] As described above, the vacuum port 57 for intake/exhaust of the annular groove 46 and the gas inlet port 55 and the gas exhaust port 56 for the gas replacement in the interior of the clean box are provided on the side surface of the clean box body 41 . On the other hand, a gas unit 50 having a vacuum exhaust/release mechanism 53 (hereinafter referred to as a vacuum mechanism), a gas feed mechanism 51 and a gas discharge mechanism 52 in cooperation with each port of the clean box body 41 is provided on the table 21 (load port table).

[0080] The gas unit 50 is installed on a slider mechanism 29 provided on the load port table 21 . The gas unit 50 is movable between a standby position ( FIG. 2A ) apart from the clean box 40 on the load port table 21 and an operative position in contact with each port 55 , 56 and 57 of the clean box 40 by the slider mechanism 29 .

[0081] When the gas unit 50 is located in the operative position, the vacuum port 57 , the gas input port 55 and the gas output port 56 of the clean box 40 are in intimate contact with and aligned with the vacuum mechanism 53 , the gas feed mechanism 51 and the gas discharge mechanism 52 of the gas unit 50 , respectively.

[0082] The vacuum mechanism in cooperation with the vacuum port 57 and the vacuum port will now be described in more detail with reference to FIG. 4 that is an enlarged view of a primary portion of FIG. 2B .

[0083] As shown in FIG. 4 , the vacuum port 57 installed on the side surface of the clean box 42 includes a valve mechanism for performing the vacuum exhaust (or evacuation) of the annular groove 46 . The valve mechanism includes a valve body 61 installed movable in the right and left directions of the drawing. The valve body 61 is composed of a closing flanged portion 61 a for closing an end portion opening 60 a of a passage 60 that is in communication with the annular groove 46 , an engagement flanged portion 61 c located on the opposite side thereof and a cylindrical shaft portion 61 b for connecting both flanged portions to each other. A surface on the right side of the closing flanged portion 61 a (on the opposite side to the surface confronting the passage 60 ) is biased in the left direction of FIG. 4 by a coiled spring 62 . Namely, usually, the valve body 61 is pushed in a direction in which the valve body 61 closes the end portion opening 61 a of the passage 60 to thereby air-tightly seal the passage 60 by the closing flanged portion 61 a . In order to keep the seal property, an O-ring 63 is provided on the left surface of the closing flanged portion 61 a so as to surround the opening 60 a.

[0084] When the gas unit is moved to the operative position, the vacuum port 57 of the clean box 40 and the vacuum mechanism 53 of the gas unit 50 are in contact with and in alignment with each other. The interface between the vacuum port and the vacuum mechanism 53 is sealed by an O-ring 68 .

[0085] The vacuum mechanism 53 of the gas unit 50 on the load port 20 has an actuator (air cylinder) 66 for releasing the closure of the passage 60 by the above-described valve body 61 . A cylindrical portion 66 a of the actuator 66 is movable linearly in the right and left directions of FIG. 4 and pivotal about an axis. A hook arm 67 is provided at an upper portion of the cylindrical portion 66 a . When the clean box 40 is set on the load port table 21 , the hook arm 67 is introduced into the vacuum port 57 of the lid 42 as indicated by a solid line in FIG. 4 .

[0086] The hook arm 67 is pivotally and linearly moved by the actuator 66 so that the tip end of the hook arm 67 may be overlapped with the engagement flanged portion 61 c of the valve body 61 as indicated by two dot and dash line in FIG. 4 in the direction of the axis. Under this condition, when the actuator 66 is operated in the straight line movement so that the hook arm 67 is moved in the right direction, the hook arm 67 is engaged with the engagement flange 61 c , the valve body 61 as a whole is moved in the right direction against the expansion force of the spring 62 . Thus, the closure of the end portion opening 60 a of the passage 60 by the closing flange 61 a is released so that the annular groove 46 is in communication with the space S 1 through the passage 60 . In this state, the annular groove 46 can be evacuated through a pipe 65 that is in communication with the space S 1 , or inversely, the gas can be introduced into the annular groove 46 that is kept under the vacuum condition to thereby release the vacuum.

[0087] The structure of the vacuum port 57 and the vacuum exhaust means has been described above. However, as a matter of fact, the clean box 40 is set on the load port 20 with the annular groove 46 and the passage 60 being evacuated. Therefore, the closing flange 61 a of the valve body 61 is strongly pressed on the side of the passage 60 by the pressure difference between the inside and outside, i.e., the pressure difference between the space S 1 and the space on the side of the passage 60 . So, it is difficult to move the valve body 61 by the hook arm 67 to open the opening 60 a.

[0088] Accordingly, in the case where the lid of the clean box 40 is to be opened, the following steps will be taken. First of all, the space S 1 is evacuated through the passage 65 so that the pressure difference between the inside and outside of the closing flange 61 a is obviated or suppressed. Thus, it is possible to release the closure of the passage 60 by the valve body 61 (closing flange 61 a ) by the hook arm 67 in accordance with the above-described sequence of the steps. After the closure of the passage 60 has been released, the passage 60 is released to the atmosphere or the air is introduced into the passage 60 so that the space S 1 , the passage 60 and the annular groove 46 becames equal to the atmospheric pressure. Thus, the vacuum suction seal between the lid 42 and the clean box body 41 is released to thereby make it possible to open the lid 42 .

[0089] Inversely, a process for vacuum exhausting the annular groove 46 to suck the lid 42 and the clean box body 41 will be described as follows. First of all, under the condition that the closing flange 61 a is opened, the passage 65 is connected to the vacuum source so that the annular groove 46 is evacuated through the space S 1 and the passage 60 . Subsequently, the actuator 66 is operated to release the engagement between the hook arm 67 and the engagement flange 61 c in the opposite order of the steps to the above-described order. Thus, the valve body 61 is moved in the left direction by the force of the spring 62 to thereby close the opening 60 a of the passage 60 . Thereafter, the passage 65 is opened to the atmosphere. Thus, the side on the passage 60 is kept under the vacuum condition and the space S 1 is kept at the atmospheric pressure so that the closing flange 61 firmly closes the passage 60 by the pressure difference between the inside and outside.

[0090] A mechanism for replacing the gas within the interior of the clean box 40 will now be described with reference to FIG. 4 .

[0091] As described briefly before, the gas input port 55 and the gas output port 56 are arranged and juxtaposed on the side surface of the clean box body 41 for introducing and discharging the gas with respect to the clean box 40 . The gas ports 55 and 56 and the related gas feed mechanism 51 and the gas discharge mechanism 52 on the load port will now be described in more detail. The gas input port 55 and the gas output port 56 , and the gas feed mechanism 51 and the gas discharge mechanism 52 have the same structure, respectively. The difference is only the flow direction of the gas. Here the gas feed mechanism 51 and the gas input port 55 on the input side will be exemplified and explained.

[0092] As shown in FIG. 4 , the gas input port 55 has a valve assembly 70 fixed to the clean box body 41 by screws 78 . The valve body 71 is installed to be movable in the right and left directions of FIG. 4 within the valve assembly 70 . The valve body 71 is biased in the right direction of FIG. 4 by two coiled springs 72 a and 72 b arranged around the valve body 71 . Normally, under this biased condition, the peripheral portion of the end surface 71 a of the valve body 71 is in contact with the inner surface 70 a of the valve assembly to close the outer opening 70 b of the valve assembly. An O-ring is provided in the peripheral portion of the end face 71 a of the valve body for keeping seal property of this closure. A filter 73 is mounted on an opening on the side, of the clean box, of the valve assembly. Accordingly, the contamination substance is prevented from entering from the outside to the clean box.

[0093] Under the condition that the gas unit 50 is located in the operative condition, the gas input port 55 and the gas feed mechanism 51 are in alignment with and in contact with each other. The interface between the gas input port 55 and the gas feed mechanism 51 is sealed by the O-ring 75 .

[0094] The gas feed mechanism 51 has an air cylinder 76 for opening the valve assembly 70 of the gas input port 55 . The air cylinder 76 has a cylinder pin 77 that is movable in the right and left directions of FIG. 4 by a pneumatic pressure. The cylinder pin 77 is in alignment with the valve body 71 of the valve assembly 70 .

[0095] In the case where non-oxidizing gas such as nitrogen gas is introduced into the clean box, the air cylinder is actuated, and the cylinder pin 77 is moved in the left direction to push the valve body 71 against the biasing force of the coiled springs 72 a and 72 b and to open the end portion opening 70 b of the valve assembly 70 . Then, the gas is fed through the passage 79 connected to the gas source.

[0096] The structure of the gas output port 56 and the gas discharge mechanism 52 on the gas output side is the same as the above-described gas input port 55 and gas feed mechanism 51 except that the gas is introduced through the passage 79 on the input side, whereas the gas is caused to flow out (discharged) on the output side. Accordingly, the explanation therefor will be omitted.

[0097] The valve assemblies of the gas input port and the gas output port are both simultaneously kept in the opened condition by the gas feed mechanism 51 and the gas discharge mechanism 52 and the non-oxidizing gas is fed from the passage 79 of the gas feed mechanism 51 so that the gas in the interior of the clean box 40 is purged and replaced by the non-oxidizing gas.

[0098] A mechanical latch is provided on the clean box lid 42 for preventing the lid 42 from falling apart from the clean box body 41 . This mechanism prevents the lid 42 from falling apart in the case where the vacuum suction between the clean box body 41 and the lid 42 by the annular groove 46 fails due to some reason during the transfer of the clean box or the like. This latch mechanism will be explained with reference to FIG. 5 .

[0099] This latch mechanism includes a circular rotary cam plate 101 disposed rotatably substantially about the center of the lid 42 . Two cam grooves 101 a and 101 b are formed in the rotary cam plate. Also, the latch mechanism includes slide type latch members 103 and 104 . The latch members 103 and 104 are slidable up and down in the drawing while being guided by guide members 106 and 107 , respectively. Cam pins 105 and 106 are implanted on the latch members 103 and 104 , respectively, and the cam pins 105 and 106 are engaged with cam grooves 101 a and 101 b of the rotary cam plate 101 , respectively.

[0100] As shown in FIG. 5 , the respective cam grooves 101 a and 101 b are formed so that a distance from the center of the rotary cam plate 101 changes in accordance with a circumferential position. In accordance with the cam shape, when the rotary cam plate 101 is fully rotated counterclockwise to be located in the position shown in FIG. 5 , the respective latch members 103 and 104 are caused to slide on the outermost position so that the respective tip end portion 103 a and 103 b project from the periphery of the lid 42 . In the case where the lid is mounted on the clean box body 41 , the projected tip end portions 103 a and 104 a overlap with the inside of the tabs (not shown) provided on the clean box body 41 to latch the lid to the clean box body 42 . Inversely, when the rotary cam plate 101 is fully rotated clockwise, the latch members 103 and 104 are caused to slide in the innermost position as indicated by the two-dot and dash line in the drawing. At this time, the tip ends 103 a and 104 a of the latch members are retracted from the periphery of the lid and are kept in the condition that they are not in cooperation with the tabs of the clean box.

[0101] Note that the latch mechanism is simply used for preventing the lid from falling apart in case of emergency. Namely, as a matter of fact, the lid 42 and the box body are firmly sucked to each other by the gas discharge of the annular groove 46 and the lid is not mainly retained by this latch mechanism. Accordingly, the cooperation between the latch members 103 and 104 and the tabs may be the non-contact cooperation. Namely, under the condition that the lid 42 is sucked, it is sufficient that the tip end portions 103 a and 104 a are overlapped with the tabs as viewed from below. If such a non-contact cooperation is taken, there is no frictional contact between the latch members 103 and 104 and the tabs when the latch mechanism is operated and no contaminative particle is generated, which is suitable for the mechanism.

[0102] A latch drive portion 109 for drivingly rotating the cam plate 101 is provided at the center of the rotary cam plate 101 . Circumferential holes 101 c are formed in the latch drive portion 109 .

[0103] A latch opening/closing mechanism 120 is provided on the elevator 22 of the lid opening/closing mechanism 23 of the load port 20 in alignment with the above-described latch drive portion 109 when the clean box 40 is set at a predetermined position on the load port table 21 . This is shown in FIG. 6 . The latch opening/closing mechanism 120 has a rotary member 122 that is rotatable about an axis A and an air actuator 121 for drivingly rotating the rotary member 122 with an air pressure. Two pins 123 are caused to project from the upper portion of the rotary member. When the clean box 40 is set at the predetermined position, these pins 123 are engaged with the circumferential holes 101 c of the latch drive portion 109 . Under this condition, the air actuator is operated and the rotary member 122 is rotated to thereby rotate the rotary cam plate 101 through the latch drive portion to make it possible to engage and disengage the latch of the lid 42 .

[0104] It will now be described how to perform the transfer of the semiconductor wafer and the delivery to the semiconductor wafer processing apparatus 10 by the clean box 40 in the clean transfer system in accordance with the present embodiment. Note that in the present embodiment, it is assumed that the lid of the clean box 40 that has been transferred is sucked and sealed to the clean box body by the vacuum exhaust of the annular groove 46 and the interior of the clean box is filled with the replacement gas having the non-oxidizing property, kept substantially at the atmospheric pressure.

[0105] The clean box 40 that has been transferred from another place by a man power or a transfer system such as an OHT or from another processing device is set on the load port 20 so that the positioning holes (not shown) formed in the lid 42 of the bottom of the clean box and the positioning pins (not shown) provided on the elevator of the load port are engaged with each other.

[0106] The following process is automatically performed in accordance with a computer control of the semiconductor wafer processing apparatus 10 . The respective steps of the following process have been already described in detail.

[0107] When the clean box is set at in the predetermined position, the annular groove 26 in the top surface of the load port table 21 confronting the second flanged portion 41 b of the clean box body 41 is evacuated by a suitable means (not shown) to thereby air-tightly sealed the clean box body 41 and the load port table. Thus, the system composed of the interior of the clean box 40 and the semiconductor wafer processing apparatus 10 is air-tightly sealed against the outside and to maintain this system as the clean space.

[0108] At the same time, the clean box lid 42 is sucked (through, e.g., vacuum suction) by the top surface of the elevator 22 of the load port by using a suitable means (not shown) so as to be clamped to the top surface of the elevator 22 . Alternatively, the lid may be clamped by a mechanical means.

[0109] Subsequently, the mechanical latch of the clean box lid 42 is released by the latch opening/closing mechanism 120 of the clean box opening/closing mechanism 23 .

[0110] Subsequently, the slider mechanism 29 of the load port is operated so that the gas unit 50 is moved to the operative position where it contacts with each port of the clean box.

[0111] Subsequently, the annular groove 46 of the clean box lid 42 is released to the atmospheric pressure in the order of the above-described steps or the gas is introduced thereinto by the vacuum mechanism 53 of the gas unit 50 to release the vacuum suction between the lid 42 and the clean box body 41 .

[0112] The above-described two processes make it possible to remove the lid 42 away from the clean box body.

[0113] Then, the elevator 22 is lowered so that the lid 42 of the clean box that has been sucked to the elevator 22 is moved downwardly together with the wafer carrier 43 fixed to the lid. As a result, the lid 42 of the clean box 40 is opened and moved to the position shown in FIG. 1 .

[0114] Here, a transfer robot 31 of the apparatus body 30 picks up the wafers W one by one from the carrier 43 through the opening 37 between the apparatus body 30 and the load port 20 with its swing arm 31 b . The transfer robot can be descended or ascended by the elevator 31 a . It is possible to pick up the wafers, in order, within the carrier 43 by changing the height.

[0115] In accordance with the vertical movement of the elevator 31 a and the swing motion of the swing arm 31 b , the transfer robot 31 causes the wafer W that has been picked up from the carrier to be laid on the stage 35 of the semiconductor wafer processing apparatus 10 .

[0116] The wafer W that has been processed on the stage 35 by the semiconductor processing apparatus is returned and laid on the carrier 43 in the opposite order as that described above by the transfer robot 31 .

[0117] When all the wafers within the carrier 43 or a desired number of wafers W have been processed, the elevator 22 of the load port 20 is raised up to a predetermined uppermost position, i.e., a predetermined position where the lid 42 again closes the clean box body 41 .

[0118] The annular groove 46 of the lid 42 is vacuum exhausted by the vacuum mechanism 53 of the gas unit to thereby perform the air-tight seal between the lid 42 and the clean box body 41 .

[0119] Subsequently, the latch drive portion 109 of the lid 42 is driven by the latch opening/closing mechanism 120 to make the latches 103 and 104 effective. Since the latch is effected after the sealing operation of the clean box, even if the particle is generated by the friction of the related mechanisms when the latch is effected, the particle is never introduced into the clean box.

[0120] Subsequently, the gas feed mechanism 51 and the gas discharge mechanism 52 of the gas unit are operated so that the interior of the clean box is displaced by the non-oxidizing gas such as nitrogen. Note that in the case where the interior of the semiconductor processing apparatus is kept under the non-oxidizing gas environment, this gas displacement process is not necessary.

[0121] Subsequently, the suction of the lid 42 by the elevator 22 and the vacuum suction between the load port table 21 and the second flanged portion 41 b of the clean box are released. Thus, the clean box 40 may be moved to a next processing device or a reserving place.

[0122] In the above-described embodiment, the annular groove 46 for performing the air-tight seal between the clean box body 41 and the lid 42 is provided on the side of the lid 41 . Of course, it is possible to provide this in the first flange 41 a that is the surface confronting the lid on the side of the clean box body.

[0123] A second embodiment of the present invention will now be described.

[0124] FIG. 7 schematically shows a local clean space system of a semiconductor manufacture apparatus including a clean box in accordance with an embodiment of a clean system of the present invention.

[0125] In FIG. 7 , the semiconductor wafer processing apparatus 210 is composed of an apparatus body 230 and a load port 220 for loading a semiconductor wafer within a clean box 240 into the processing device. An interface between the apparatus body 230 and the load port 220 is designated by a line A in FIG. 7 . Usually, the load port 220 is formed as a discrete device that is detachably mounted on the apparatus body 230 . However, the load port may be formed integrally with the apparatus body. The apparatus body 230 is in communication with the load port 220 through an opening 237 formed at a portion indicated by a dotted line on the line A of FIG. 7 for sending and receiving the semiconductor wafer between the load port and the apparatus body through the opening 237 .

[0126] The space within the apparatus body 230 and the space of the load port 220 are in communication with each other through the above-described opening 237 so that the overall interior of the device 210 including both constitutes the local clean space. In order to keep the space clean, a fan intake blower device 232 having a filter is provided at an upper portion of the semiconductor wafer processing apparatus 210 . A downstream air flow is generated within the apparatus by the fan intake blower device 232 to thereby keep the space within the semiconductor wafer processing apparatus 210 clean. The downstream air flow is discharged from the bottom of the apparatus to the outside.

[0127] In FIG. 7 , the clean box 240 in accordance with the present invention is set on a table 221 of a top surface of the load port 220 . The clean box 240 is a sealed type container composed of a box-shaped clean box body 241 that opens at its bottom and a lid 242 for covering the opening of the bottom of the body. As will be described in more detail later, when the clean box 240 is laid on the table 221 of the load port 220 and the wafer W within the clean box 240 is entered and removed, the interface between the clean box body 241 and the table 221 is sealed by a vacuum suction using the annular groove (indicated by reference numeral 226 in FIG. 8 ) formed on the table 221 to thereby maintain the clean space against the outside.

[0128] The clean box 240 is a container to be used for transfer of wafer among different devices and temporary deposit of the wafer. The clean box 240 has a carrier 243 fixed to the lid 242 . The carrier 243 is a rack type structure for receiving a plurality of wafers in parallel and at an equal interval.

[0129] The load port 220 has an elevator type clean box opening/closing mechanism 223 for opening/closing the lid 242 of the clean box 240 and moving the lid 242 downwardly together with carrier 243 to make it possible to pick up the wafers within the carrier. As will be described in more detail later, the clean box opening/closing mechanism 223 has also a mechanism for replacing the interior within the clean box by the gas. The clean box 240 is transferred by a transfer means such as an overhead transfer (OHT) system within the factory and is set on the table 221 of the load port 220 . In some cases, the transfer of the clean box may be manually performed directly by the operator.

[0130] The clean box 240 will now be described in more detail with reference to FIGS. 8 and 9 . FIGS. 8 is a side elevational view showing, partly in cross-section, the clean box 240 mounted on the load port 220 and a top portion of the clean box opening/closing mechanism 223 of the load port, and FIG. 9 is a view showing a bottom surface of the clean box 240 .

[0131] The clean box body 241 is a container having a substantially square shape. A two stage flanged portion, i.e., a first flanged portion 241 a and a second flanged portion 241 b are provided around the periphery of the clean box body 241 . A groove 246 is provided on that peripheral portion of the top surface of the clean box 40 which confronts the first flanged portion 241 a of the clean box body 241 . The groove 246 is an annular groove 246 formed so as to surround the peripheral portion of the lid 242 confronting the first flanged portion 241 a of the clean box 240 . O-rings for sealing the annular groove 246 are also mounted on the inside and outside of the annular groove 246 on the lid 242 so as to surround the peripheral portion of the lid also in annular shapes in a well known manner.

[0132] In the clean box 240 according to the present invention, this annular groove 246 is vacuum exhausted to thereby air-tightly seal the interface between the clean box body 241 and the lid 242 by the vacuum suction. Namely, the seal force may be insured by the differential pressure between the outside atmospheric pressure and the vacuum pressure within the annular groove 246 . The vacuum exhaust of the annular groove 246 is performed through a vacuum port 257 (see FIG. 10 ) that is an intake/exhaust port provided on the bottom surface (i.e., outer surface) of the lid 242 . The vacuum exhaust will be described later in detail.

[0133] Gas ports 255 and 256 are provided at the lid 242 for replacing the gas in the interior of the box by the non-oxidizing gas (nitrogen gas, inert gas or the like). One of them is a gas input port 255 for introducing the gas and the other is an output port 256 for discharging the gas. The lid 242 further includes mechanical latches 103 and 104 for preventing the lid from falling apart from the box body in cooperation with the tabs 110 of the clean box body 241 and the latch drive portion 109 for driving the latches. The various mechanisms related to the mechanical latches are the same as those described in conjunction with the first embodiment.

[0134] The above-described clean box 240 may keep the article to be transferred such as a semiconductor wafer W or the like on the carrier 243 and transfer and store the article while sealing the non-oxidizing clean gas such as nitrogen in a sealed condition within the clean box by the suction of the annular groove 246 .

[0135] The relationship between the clean box 240 and the load port 220 will now be described. In the case where the article to be transferred such as a semiconductor wafer to be transferred by the clean box is to be loaded on the semiconductor wafer processing apparatus, as shown in FIG. 8 , the clean box 240 is set on the table 221 of the load port 220 . Positioning holes 254 a , 254 b and 254 c of the clean box bottom (see FIG. 9 ) are engaged with positioning pins (not shown) provided on the top surface of the elevator 222 of the upper portion of the clean box opening/closing mechanism of the load port so that the lid 242 of the clean box and the elevator 222 of the load port are positioned in alignment with each other. The elevator 222 is mounted on the uppermost surface of the elevator type clean box opening/closing mechanism 223 and may be movable up and down together with the clean box opening/closing mechanism 223 by a mechanism not shown.

[0136] An annular groove 226 surrounding the periphery of the elevator 222 and two annular O-rings 225 for sealing the annular groove 226 are provided at a position confronting with the second flanged portion 241 b of the clean box body 241 on the top surface of the load port table 221 under the thus positioned condition. The groove 226 is evacuated to thereby air-tightly seal the interface between the clean box body 241 and the load port table 221 . An O-ring 227 is provided also to the elevator 222 for sealing the interface between the elevator 222 and the table 221 . This is done for the purpose of sealing the inner clean space of the semiconductor wafer processing apparatus 210 against the outer space when the clean box is not used.

[0137] A vacuum exhaust/release mechanism (hereinafter referred to as a vacuum mechanism) 253 is laid in a position in alignment with the vacuum port 257 of the lid 242 under the above-described positioned condition on the elevator 222 of the clean box opening/closing mechanism 223 . In the same manner, a gas feed mechanism 251 and a gas discharge mechanism 252 are provided at a position in alignment with a gas input port 255 and at a position in alignment with a gas output port 256 , respectively.

[0138] The vacuum port 257 provided in the lid 242 will now be described with reference to FIG. 10 . FIG. 10 is a side elevational view showing, partly in cross section, a vacuum port portion 257 of the lid and a vacuum mechanism 253 on the side of the clean box opening/closing mechanism 223 of the load port related to the vacuum port portion. As shown in FIG. 10, a valve mechanism is provided in the interior of the lid 242 for performing the vacuum exhaust of the annular groove 246 . The valve mechanism includes a valve body 261 installed movable up and down. The valve body 261 is composed of a closing flanged portion 261 a for closing a passage 260 in communication with the annular groove 246 , an engagement flanged portion 261 c opposite to the closing flanged portion 261 a and a cylindrical shaft portion 261 b for connecting the two portions with each other. A bottom surface of the closing flanged portion 261 a (a surface opposite to the surface confronting the passage 260 ) is biased upwardly by a coiled spring 262 . Namely, the valve body 261 is normally pressed in a direction to close the passage 260 . The passage 260 is air-tightly sealed by the closing flanged portion 261 a . In order to keep the air-tight state, an O-ring 263 is provided on the top surface of the closing flanged portion 261 a.

[0139] The vacuum mechanism 253 of the clean box opening/closing mechanism 223 on the side of the load port 220 has an actuator (air cylinder) 266 for releasing the closure of the passage 260 by the above-described valve body 261 . A cylindrical portion 266 a of the actuator 266 may be pivotally moved about the shaft and linearly moved up and down by the air pressure. A hook arm 267 is provided at an upper portion of the cylindrical portion 266 a . When the clean box 240 is laid on the load port table 221 , the hook arm 267 is introduced into the vacuum port 257 of the lid 242 as indicated by the solid line in FIG. 10 . Under this condition, the position of the hook arm is also shown by the solid line in FIG. 11 which is a perspective view as viewed from the line V-V of FIG. 10 .

[0140] The actuator 266 is operated to pivotally move the hook arm 267 to the position depicted by the two-dot and dash line in FIGS. 10 and 11 so that the end of the hook arm and the engagement flanged portion 261 c of the valve body 261 are overlapped with each other in the axial direction. Under this condition, when the actuator 266 is operated in the linear direction and the hook arm 267 is drawn downwardly, the hook arm 267 is engaged with the engagement flange 261 c and the valve body 261 as a whole is drawn downwardly against the expansion force of the spring 262 . Thus, the closure of the passage 260 by the closing flange 261 a is released so that the annular groove 246 is in communication with the space S 1 through the passage 260 . Thus, it is possible to evacuate the annular groove 246 by the passage 265 in communication with the space S 1 and inversely release the vacuum by introducing the gas into the annular groove 246 which has been evacuated.

[0141] Note that the O-ring 268 is disposed to surround the vacuum mechanism 253 on the top surface of the elevator 222 and imparts the seal with the lid 242 .

[0142] The structure of the vacuum port 257 and the vacuum discharge means has been described above. As a matter of fact, the lid 242 of the clean box is disposed on the load port under the condition that the annular groove 246 and the passage 260 are evacuated. Accordingly, the closing flange 261 a of the valve body 261 is strongly pushed against the passage 260 by the pressure difference between inside and outside, i.e., the pressure difference between the space on the side of the passage 260 and the space S 1 . So, it is difficult to draw the valve body 261 downwardly by the hook arm 267 </