JP2018160543A - EFEM and EFEM gas replacement method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an EFEM or the like capable of efficiently replacing an internal environment with an environment filled with a replacement gas. SOLUTION: A gas introduction section for introducing a replacement gas, a first chamber provided with an inflow port into which the replacement gas flows from the gas introduction section, and a lower part of the first chamber are connected to convey a wafer. A second chamber in which a transfer robot is provided, an airflow forming portion that forms a downdraft from the first chamber to the second chamber, and a gas discharging portion that discharges gas from the second chamber to the second chamber. An EFEM comprising a differential pressure forming mechanism that forms a predetermined pressure difference between the first chamber and the second chamber so that the pressure in the first chamber becomes larger than the pressure in the second chamber. [Selection diagram] Fig. 3

Description

  The present invention relates to an EFEM and a gas replacement method of EFEM for transferring a wafer from a transfer container to a processing chamber in a semiconductor factory.

  In a semiconductor manufacturing process, a wafer is transferred between processing apparatuses using a wafer transfer container called a FOUP or a FOSB. Further, an EFEM (Equipment Front End Module) is used when transferring a wafer from such a wafer transfer container to a processing chamber. The EFEM forms a space called a mini-environment, which is cleaner than the environment in the factory, and transfers the wafer between the wafer transfer container and the processing chamber through this space. Therefore, the environment in which the wafer is exposed is maintained clean even during transfer from the wafer transfer container to the processing chamber, and the wafer can be protected from oxidation or the like (see Patent Document 1).

JP 2000-82731 A

  In recent years, in order to further improve the cleanliness inside the EFEM, there has been proposed one in which an inert gas such as nitrogen is introduced into the EFEM. In such an EFEM, since the inside of the mini-environment is an inert gas atmosphere such as nitrogen, the wafer can be effectively protected from oxidation and the like.

  However, the EFEM that introduces nitrogen needs to be replaced again with nitrogen gas when it becomes necessary to maintain the atmosphere in the atmosphere due to maintenance or the like. In such an EFEM, it takes time to replace the inside of the EFEM with nitrogen. However, in order to reduce the downtime of the apparatus in the semiconductor factory and improve the production efficiency, it is possible to reduce the time required for gas replacement. It has been demanded.

  The present invention is made in view of such a situation, and is to provide an EFEM and an EFEM gas replacement method capable of efficiently replacing the internal environment with an environment filled with gas.

In order to achieve the above object, the EFEM according to the present invention is:
A gas introduction part for introducing a replacement gas;
A first chamber provided with an inlet through which the replacement gas flows from the gas inlet;
A second chamber connected to the lower side of the first chamber and provided with a transfer robot for transferring wafers;
An airflow forming unit that forms a downward airflow from the first chamber toward the second chamber;
A gas discharge unit for discharging the gas in the second chamber from the second chamber;
A differential pressure forming mechanism that forms a predetermined pressure difference between the first chamber and the second chamber so that the pressure in the first chamber is higher than the pressure in the second chamber;
Have

  In the EFEM according to the present invention, the differential pressure forming mechanism generates a pressure difference between the first chamber and the second chamber, and makes the pressure in the first chamber higher than the pressure in the second chamber. In such an EFEM, the second chamber can be replaced with a replacement gas in a shorter time than a conventional EFEM.

  Further, for example, the differential pressure forming mechanism may include a first ventilation resistance member provided at a connection position connecting the first chamber and the second chamber and having a first ventilation resistance.

  The differential pressure forming mechanism having the first ventilation resistance member can form a predetermined pressure difference between the first chamber and the second chamber due to the ventilation resistance when the replacement gas passes through the first ventilation resistance member. it can.

Further, for example, the air flow forming portion and the first ventilation resistance member may be provided side by side in the connection position,
The replacement gas may flow from the first chamber to the second chamber through the air flow forming portion and the first ventilation resistance member.

  The EFEM in which the airflow forming portion and the first ventilation resistance member are arranged in the connection position in the vertical direction is easy to attach and detach the airflow forming portion and the first resistance member, and has good maintainability. In addition, by adopting a structure in which the first ventilation resistance member and the airflow forming portion are provided, the problem that the structure of the EFEM becomes complicated by providing the first ventilation resistance member can be prevented.

  In addition, for example, the gas discharge unit may include a second ventilation resistance member having a second ventilation resistance smaller than the first ventilation resistance, and the gas in the second chamber is the second ventilation resistance. It may be discharged through the member.

  By making the ventilation resistance (second ventilation resistance) of the second ventilation resistance member of the gas exhaust portion smaller than the ventilation resistance (first ventilation resistance) of the first ventilation resistance member provided at the connection position, the first chamber A predetermined pressure difference can be formed between the first chamber and the second chamber.

  For example, the differential pressure forming mechanism may include a forced gas discharge mechanism that forcibly discharges the gas in the second chamber from the second chamber.

  The differential pressure forming mechanism having a forced gas discharge mechanism forms a predetermined pressure difference between the first chamber and the second chamber by forcibly discharging gas from the second chamber by the forced gas discharge mechanism. Can do.

The gas replacement method of EFEM according to the present invention is as follows:
Introducing a replacement gas into the first chamber from the gas inlet through the inlet;
A gas introduction step for introducing the replacement gas into a second chamber connected to a lower portion of the first chamber and provided with a transfer robot for transferring a wafer;
Discharging the gas in the second chamber from the second chamber via a gas discharge portion;
EFEM gas replacement method comprising:
In the gas introduction step, the pressure in the first chamber is higher than the pressure in the second chamber.

  According to such a gas replacement method of EFEM, the second chamber can be replaced with the replacement gas in a shorter time compared to the conventional EFEM.

For example, in the gas introduction step,
The replacement gas passes through a first ventilation resistance member provided at a connection position connecting the first chamber and the second chamber and having a first ventilation resistance, and the first chamber is transferred to the second chamber. By flowing in,
The pressure in the first chamber may be higher than the pressure in the second chamber.

For example, in the gas introduction step,
Driving a forced gas discharge mechanism for forcibly discharging the gas in the second chamber from the second chamber;
The pressure in the first chamber may be higher than the pressure in the second chamber.

  Further, for example, in the gas introduction step, when the pressure in the first chamber is P1, the pressure in the second chamber is P2, and the pressure in the installation environment of the EFEM is P3, P1> P2> P3. May be started.

  In the EFEM gas replacement method having such a gas introduction step, the second chamber can be replaced with the replacement gas in a shorter time compared to the conventional EFEM.

FIG. 1 is a schematic view of an EFEM according to an embodiment of the present invention. FIG. 2 is a conceptual diagram showing an air flow formation state in the EFEM shown in FIG. FIG. 3 is a conceptual diagram showing an airflow formation state in the EFEM according to the second embodiment. FIG. 4 is a flowchart showing an example of a gas replacement method of EFEM. FIG. 5 is a graph showing the relationship between the differential pressure formed between the first chamber and the second chamber and the replacement time obtained from Examples 1 and 2 and the reference example.

Hereinafter, the present invention will be described based on embodiments shown in the drawings.
FIG. 1 is a schematic diagram of an EFEM 50 according to an embodiment of the present invention. The EFEM 50 (Equipment Front End Module) is provided between the FOUP 20 as a wafer transfer container for transferring the wafer 12 and a processing chamber (not shown) for processing the wafer 12 in a semiconductor factory. It is an apparatus used for conveying. As shown in FIG. 1, the EFEM 50 has a second chamber 64 in which a clean space called a mini-environment is formed, and the wafer 12 accommodated in the hoop 20 is processed through the second chamber 64. Conveyed to the room.

  In the EFEM 50 according to the present embodiment, as a replacement gas in the second chamber 64 via the first chamber 54 provided above the second chamber 64 (or the second floor portion if the second chamber 64 is the first floor portion). Nitrogen gas is introduced. The transfer of the wafer 12 between the FOUP 20 and the processing chamber is performed in a state where the second chamber 64 is replaced with nitrogen gas. The replacement of nitrogen gas in the EFEM 50 will be described in detail later.

  In addition to the first chamber 54 and the second chamber 64, the EFEM 50 includes a gas introduction unit 42, an airflow formation unit 60, a gas discharge unit 68, a differential pressure formation mechanism 72, a load port device 80, a transfer robot 90, and the like.

  The load port device 80 is provided on the wall portion of the second chamber 64. The load port device 80 is a device for connecting the inside of the FOUP 20 and the second chamber 64 of the EFEM 50. The load port device 80 is an opening formed on the mounting table 84 on which the FOUP 20 is mounted or a wall portion of the second chamber 64. The door 86 etc. which open and close are provided.

  The FOUP 20 containing the wafer 12 therein is carried to the mounting table 84 of the load port device 80 via an OHT (Overhead Hoist Transfer) provided in the factory. The load port device 80 connects the main opening 20a of the hoop 20 to the opening formed in the second chamber 64, connects the lid 24 and the door 86 that close the main opening 20a of the hoop 20, and then connects the lid 24 and the door. 86 are moved into the second chamber 64. In this way, the load port device 80 can open the main opening 20a of the hoop 20 and allow the hoop 20 and the second chamber 64 to communicate with each other.

  The gas introduction part 52 of the EFEM 50 is provided in the ceiling part of the first chamber 54. As shown in FIG. 2, the gas introduction unit 52 introduces nitrogen gas, which is a replacement gas, into the first chamber 54. Nitrogen gas is supplied to the gas introduction unit 52 from an unillustrated nitrogen gas tank or the like via the introduction flow path 51. The replacement gas may be an inert gas other than nitrogen gas. In FIG. 2, the load port device 80 and the transfer robot 90 shown in FIG. 1 are not shown.

  As shown in FIG. 2, the first chamber 54 is connected to the upper portion of the second chamber 64, and the first chamber 54 is disposed immediately above the second chamber 64. The first chamber 54 includes an inflow port 56 into which nitrogen gas flows from the gas introduction unit 52, and nitrogen gas is introduced into the first chamber 54 from the gas introduction unit 52.

  The width of the first chamber 54 is not particularly limited. For example, the length in the height direction of the first chamber 54 is shorter than the second chamber 64 below, and the projected area from above the first chamber 54 is This is the same as the second chamber 64 below. By making the space of the first chamber 54 narrower than the space of the second chamber 64, the pressure of the first chamber 54 can be increased efficiently and the size of the EFEM 50 can be prevented from increasing.

  The first chamber 54 includes a first pressure gauge 55 that measures the pressure in the first chamber 54. The measured value of the first pressure gauge 55 is transmitted to a control unit (not shown).

  As shown in FIG. 2, the second chamber 64 is connected below the first chamber 54. As shown in FIG. 1, the second chamber 64 is provided with a transfer robot 90 for transferring the wafer 12. The transfer robot 90 has a movable arm that transfers the wafer 12. The transfer robot 90 takes out the wafer 12 from the main opening 20a of the FOUP 20 communicating with the second chamber 64 using a movable arm, and transfers the wafer 12 to the processing chamber. Further, the transfer robot 90 uses the movable arm to transfer the processed wafer 12 from the process chamber to the FOUP 20.

  The second chamber 64 includes a second pressure gauge 65 that measures the pressure in the second chamber 64 and an oxygen concentration meter 66 that measures the oxygen concentration in the second chamber 64. A third pressure gauge 78 for measuring the pressure P3 in the installation environment of the EFEM 50 is provided on the outer wall of the second chamber 64. The measured values of the second pressure gauge 65, the oxygen concentration meter 66, and the third pressure gauge 78 are transmitted to a control unit (not shown).

  As shown in FIG. 2, the gas discharge unit 68 is provided under the floor of the second chamber 64. The gas discharge unit 68 discharges the gas in the second chamber 64 from the second chamber 64. The gas in the second chamber 64 discharged from the gas discharge unit 68 includes both nitrogen gas, which is a replacement gas, and air. Although the gas discharge part 68 which concerns on this embodiment is a natural exhaust mechanism which does not have a ventilation means like a fan, as the gas discharge part 68, the forced exhaustion mechanism which has a ventilation means may be sufficient.

  The gas discharge unit 68 includes a second ventilation resistance member 69 having a second ventilation resistance. In the present embodiment, the second ventilation resistance member 69 is a filter-like member having an area equivalent to the connection surface connecting the second chamber 64 and the gas discharge portion 68, and the gas in the second chamber 64 is 2 It passes through the ventilation resistance member 69 and is discharged. Examples of the second ventilation resistance member 69 in the gas discharge unit 68 include a fibrous member such as a fibrous material filter, a porous member such as a sintered body filter, and a sponge. Other members or structures that generate

  The gas discharge part 68 is connected to the exhaust flow path 71 for discharging gas. The pressure in the exhaust flow path 71 can be, for example, approximately the same as the atmospheric pressure, but may be a lower pressure than the second chamber 64 and may be a negative pressure.

  As shown in FIG. 2, the airflow forming unit 60 is provided at a connection position 58 that connects the first chamber 54 and the second chamber 64. The air flow forming unit 60 includes a blower fan 61 and forms a downward air flow from the first chamber 54 toward the second chamber 64. The arrows in FIG. 2 represent the flow of the replacement gas introduced from the gas introduction part 52, passing through the first chamber 54, the connection position 58, and the second chamber 64 and exhausted from the gas exhaust part 68. As shown by the arrow in FIG. 2, the blower fan 61 can form a downflow of nitrogen gas in the second chamber 64.

  The air flow forming unit 60 may be the blower fan 61 alone or a fan filter unit (FFU) in which the blower fan 61 and another filter are integrated. The blower fan 61 includes, but is not limited to, a fan having a motor that rotates the splash and the splash that is inclined with respect to the rotation direction. Moreover, as a filter which comprises a fan filter unit with the ventilation fan 61, what combined the particle removal filter and the chemical filter is mentioned, for example, It is not specifically limited.

  In the EFEM 50 according to the embodiment, the airflow forming unit 60 is disposed at the connection position 58 between the first chamber 54 and the second chamber 64, but the arrangement of the airflow forming unit 60 is not limited thereto. For example, you may arrange | position on the ceiling of the 1st chamber 54, etc.

  As shown in FIG. 2, the differential pressure forming mechanism 72 of the EFEM 50 includes a first ventilation resistance member 73 having a first ventilation resistance. The first ventilation resistance member 73 is provided at a connection position 58 that connects the first chamber 54 and the second chamber 64, and the airflow forming portion 60 and the first ventilation resistance member 73 are arranged vertically at the connection position 58. Is provided. As shown in FIG. 2, in the EFEM 50 of the present embodiment, the first ventilation resistance member 73 is disposed on the airflow formation unit 60, but the first ventilation resistance member 73 is below the airflow formation unit 60. It may be arranged.

  The ventilation resistance (first ventilation resistance) of the first ventilation resistance member 73 is larger than the ventilation resistance (second ventilation resistance) of the second ventilation resistance member 69 of the gas discharge unit 68, and the first ventilation resistance member 73 It is more difficult for nitrogen gas and air to pass through than the second ventilation resistance member 69. That is, the ventilation resistance of the second ventilation resistance member 69 included in the gas discharge unit 68 is smaller than the ventilation resistance of the first ventilation resistance member 73.

  In addition, when the airflow forming unit 60 provided along with the airflow resistance member such as a filter, the airflow resistance of the first airflow resistance member 73 is preferably larger than the airflow resistance of the airflow resistance member included in the airflow forming unit 60. . Examples of the first ventilation resistance member 73 included in the differential pressure forming mechanism 72 include a fibrous member such as a fibrous material filter, a porous member such as a sintered body filter, and a sponge. Other members and structures that produce ventilation resistance may be used.

  In the present embodiment, the first ventilation resistance member 73 is a filter-like member having the same area as the connection passage connecting the first chamber 54 and the second chamber 64, and covers the suction port of the airflow forming unit 60. It is provided as follows. Therefore, when the blower fan 61 of the airflow forming unit 60 rotates, the nitrogen gas introduced into the first chamber 54 passes through the first airflow resistance member 73 and the airflow forming unit 60 and passes through the first chamber 54. It flows into the second chamber 64.

  The differential pressure forming mechanism 72 having such a first ventilation resistance member 73 forms a predetermined pressure difference between the first chamber 54 and the second chamber 64 due to the ventilation resistance of the first ventilation resistance member 73. In addition, as shown in FIG. 2, since nitrogen gas is introduced into the first chamber 54 and sent from the first chamber 54 to the second chamber 64, the pressure in the first chamber 54 is higher than the pressure in the second chamber 64. Get higher. Such an EFEM 50 can replace the gas in the second chamber 64 from air to nitrogen gas in a shorter time than the conventional EFEM.

  FIG. 4 is a flowchart showing an example of a gas replacement method of the EFEM 50 shown in FIG. The gas replacement of the EFEM 50 is performed, for example, after the maintenance of the EFEM 50 is completed. Before the gas replacement method for the EFEM 50 shown in FIG. 2 starts, the first chamber 54 and the second chamber 64 of the EFEM 50 are in a state filled with air.

  In step S001 shown in FIG. 4, the introduction of gas into the first chamber 54 shown in FIG. 2 is started, and the EFEM is set to the first state. In the first state, nitrogen gas is introduced into the first chamber 54 from the gas introduction part 52 through the inflow port 56. In the first state, the gas introduction step for introducing nitrogen gas into the second chamber 64 has not started. Since the EFEM 50 has the first ventilation resistance member 73 disposed between the first chamber 54 and the second chamber 64, the amount of nitrogen gas introduced into the first chamber 54 per unit time in the first state. However, the amount of gas that moves from the first chamber 54 to the second chamber 64 per unit time is exceeded, and the pressure in the first chamber 54 increases.

  In the first state, as the gas moves from the first chamber 54 to the second chamber 64, a step of discharging the gas from the second chamber 64 via the gas discharge unit 68 is started. However, the flow rate of the gas discharged from the second chamber 64 in the first state is smaller than that in the second state described later.

  In step S002 shown in FIG. 4, a gas introduction step for introducing nitrogen gas into the first chamber 54 shown in FIG. 2 is started, and the EFEM 50 is set in the second state. When the first state is continued in the EFEM 50, the pressure in the first chamber 54 increases, and a predetermined differential pressure is formed between the first chamber 54 and the second chamber 64. As the differential pressure between the first chamber 54 and the second chamber 64 increases, the flow rate of the gas moving from the first chamber 54 to the second chamber 64 increases, and the EFEM 50 changes from the first state to the second state. Migrate to In the gas introduction step, the pressure of the first chamber 54 detected by the first pressure gauge 55 is detected by P1, the pressure of the second chamber 64 detected by the second pressure gauge 65 is detected by P2, and the third pressure gauge 78 is detected. When the pressure of the installation environment of the EFEM 50 is P3, it is preferable to start from a state where P1> P2> P3. By making the pressure P2 of the second chamber 64 higher than the pressure P3 of the installation environment of the EFEM 50, it is possible to prevent the problem that the air around the EFEM 50 flows into the second chamber 64 and the oxygen concentration in the second chamber 64 increases.

  In the second state, the step of introducing the gas from the gas introduction part 52 to the first chamber 54 is continuously performed. In the second state, the amount of nitrogen gas introduced into the first chamber 54 per unit time becomes equal to the amount of gas moving from the first chamber 54 to the second chamber 64 per unit time, and the first chamber 54 The pressure becomes substantially constant.

  In the second state, the step of discharging the gas from the second chamber 64 via the gas discharge unit 68 is continuously performed. In the second state, the gas flow rate moving from the first chamber 54 to the second chamber 64 is larger than that in the first state, and the gas moving from the first chamber 54 to the second chamber 64 is almost nitrogen as time passes. Since only the gas is used, the replacement of the second chamber 64 with nitrogen gas proceeds, and the oxygen concentration in the second chamber 64 decreases.

  In addition, since the second ventilation resistance member 69 included in the gas discharge unit 68 has a ventilation resistance smaller than that of the first ventilation resistance member 73, the EFEM 50 also has the first ventilation state in the second state as in the first state. The pressure in the first chamber 54 is higher than the pressure in the second chamber 64. In the second state, the pressure in the first chamber 54 is constant, and the pressure in the second chamber 64 is also constant, so that the differential pressure between the first chamber 54 and the second chamber 64 is also constant.

  In step S003 shown in FIG. 4, the oxygen concentration in the second chamber 64 is detected using the oxygen concentration meter 66 shown in FIG. In step S004, it is determined whether the oxygen concentration detected in step S003 is equal to or less than a predetermined value y. If the oxygen concentration is higher than the predetermined value y, the second state is continued. If the oxygen concentration is lower than the predetermined value y, the process proceeds to step S005 to complete the replacement.

  When the replacement of the nitrogen gas in the second chamber 64 is completed, the EFEM 50 can drive the load port device 80 shown in FIG. 1 and transfer the wafer 12 through the second chamber 64. Note that even after the gas replacement shown in FIG. 4 is completed, in the EFEM 50, the operations of the gas introduction unit 52, the airflow formation unit 60, and the gas discharge unit 68 are continued, and the second chamber 64 is maintained in a nitrogen gas atmosphere.

  As described above, in the EFEM 50, the differential pressure forming mechanism 72 generates a pressure difference between the first chamber 54 and the second chamber 64, so that the second chamber 64 can be opened in a shorter time than the conventional EFEM. The air can be replaced with nitrogen gas. Moreover, since the 1st ventilation resistance member 73 is arrange | positioned on the airflow formation part 60, the EFEM50 is easy to attach or detach the 1st ventilation resistance member 73, and its maintainability is favorable.

  Each member of the EFEM 50 and the driving method of the EFEM 50 according to the first embodiment can be changed as long as the problem can be solved, and the present invention has many other embodiments and modifications. Needless to say. For example, the transition from the first state (step S001) to the second state (step S002) shown in FIG. 4 may be automatically performed by the formation of a differential pressure, but the first chamber 54 and the second chamber 64 may be performed. May be performed by switching the control of the EFEM 50 at a timing when a predetermined differential pressure is detected between the first chamber 54 and the second chamber 64.

  For example, in the gas replacement method according to the modified example of the present invention, the EFEM 50 starts the gas introduction step by setting the rotational speed of the blower fan 61 of the airflow forming unit 60 to be higher than that in the first state. In this case, in the first state, the blower fan 61 of the airflow forming unit 60 is rotating at a lower rotational speed or stopped than in the second state after the gas introduction step is started.

  Alternatively, in the gas replacement method according to another modification of the present invention, the rotation of the blower fan 61 is stopped in the gas introduction step of introducing nitrogen gas into the first chamber 54. That is, according to this another modification, the blower fan is stopped in a state where nitrogen gas is introduced into the second chamber 64. In the introduction of the nitrogen gas according to the modification, the gas replacement is performed in a shorter time than the forced introduction using the blower fan by performing the natural replacement only by the introduction pressure introduced from the gas introduction part 52 through the inlet 56. Is possible. This is because in the case of replacement by rotation of the blower fan, a region where turbulent flow is generated inside the second chamber 64 and replacement cannot be achieved locally occurs, whereas in the case of replacement by natural replacement, turbulent flow occurs. This is thought to be due to the fact that it becomes difficult to perform uniform replacement.

  In the EFEM according to the modification of the present invention, the connection state between the first chamber 54 and the second chamber 64 is switched between the communication state and the non-communication state between the first chamber 54 and the second chamber 64. A shutter may be provided. In the EFEM according to such a modification, the shutter is closed in the first state shown in FIG. 4, and the first chamber 54 and the second chamber 64 are not in communication. Further, after a predetermined pressure difference is formed between the first chamber 54 and the second chamber 64, the shutter is opened to bring the first chamber 54 and the second chamber 64 into communication, and the gas introduction step is started. To do.

  As shown in FIG. 2, in the EFEM 50, the first ventilation resistance member 73 is provided so as to cover the suction port of the airflow forming unit 60. You may arrange | position under the airflow formation part 60 so that a discharge port may be covered. Further, the differential pressure forming mechanism 72 is not limited to the one having the first ventilation resistance member 73, and the forced gas discharge mechanism 174 is provided like the differential pressure forming mechanism 172 in the EFEM 150 according to the second embodiment shown in FIG. You may have.

  FIG. 3 is a schematic diagram showing an EFEM 150 according to the second embodiment of the present invention. The EFEM 150 is the same as the EFEM 50 according to the first embodiment except that the differential pressure forming mechanism 172 has a forced gas discharge mechanism 174. Therefore, regarding the EFEM 150 shown in FIG. 3, only the differences from the EFEM 50 shown in FIG. 2 will be described, and the description of the common points will be omitted.

  The differential pressure forming mechanism 172 of the EFEM 150 illustrated in FIG. 3 includes a forced gas discharge mechanism 174 in addition to the first ventilation resistance member 73. The forced gas discharge mechanism 174 is provided between the gas discharge unit 68 and the exhaust passage 71. The forced gas discharge mechanism 174 includes an exhaust fan 175 for forcibly exhausting the gas from the second chamber 64 to the second chamber 64, adjustment of the amount of gas discharged from the second chamber 64, A damper 176 for preventing the backflow of gas to the two chambers 64 is provided.

  In the gas replacement method using the EFEM 150, in the first state shown in FIG. 4, the exhaust fan 175 is driven to make the pressure in the first chamber 54 higher than the pressure in the second chamber 64. As a result, the EFEM 150 forms a differential pressure between the first chamber 54 and the second chamber 64, and the second chamber 64 can be replaced with nitrogen gas from air in a shorter time than the conventional EFEM. it can. In the gas replacement method using EFEM 150, forced exhaust may be continued by exhaust fan 175 in the second state after the start of the gas introduction step. Further, in the EFEM according to another modified example, the forced gas discharge mechanism 174 may be provided by a route different from the gas discharge unit 68 that is a natural gas discharge mechanism. In the EFEM according to such a modified example, the forced gas discharge mechanism 174 may be provided. The mechanism 174 and the gas discharge unit 68, which is a natural gas discharge mechanism, can be switched using a switching valve or the like.

  Hereinafter, the EFEM according to the present invention will be described in more detail with reference to examples. However, the present invention is not limited only to these examples.

Example 1
In Example 1, the EFEM 50 shown in FIG. 2 was used to perform gas replacement in the first chamber 54 and the second chamber 64, and the time required until gas replacement was completed was investigated. Detailed conditions of the EFEM 50 used in the first example are as follows.
First chamber 54 volume: 60 Litter
Second chamber 64 volume: 750 Litter
Gas introduction part 52 flow rate: 150 l / min
Airflow forming unit 60: fan filter unit first ventilation resistance member 73: resistance filter 5 mm × 3 layer stack (BEL EATER A series manufactured by Aion Co., Ltd.)
Second ventilation resistance member 69: resistance filter 5 mm × 1 layer overlap (Aeon Co., Ltd. Beleater A series)

  In the first embodiment, gas replacement is performed by the method shown in FIG. 4, and the pressure ΔP1 in the first chamber 54 and the pressure ΔP2 in the second chamber 64 after the start of the gas introduction step in the second state are measured. The differential pressure ΔPx = ΔP1−ΔP2 between the chamber and the second pressure chamber was calculated. The pressure ΔP1 in the first chamber 54 is a measurement result of the differential pressure between the first pressure gauge 55 and the third pressure gauge 78 shown in FIG. 2, and the pressure ΔP2 in the second chamber 64 is the second pressure shown in FIG. It is a measurement result of the differential pressure between the meter 65 and the third pressure gauge 78. The replacement time T required for the replacement is the start of the introduction of nitrogen gas into the first chamber 54 with respect to the first chamber 54 and the second chamber 64 filled with air, and the oxygen concentration in the second chamber 64 The time until the (measured value of the oxygen concentration meter 66) reached 100 ppm was used. The results are shown in Table 1.

Example 2
In Example 2, gas replacement was performed in the same manner as in Example 1 except that four first resistance filters similar to the resistance filter used in Example 1 were used as the first ventilation resistance member 73. went. The results are shown in Table 1.

Reference Example In the reference example, gas replacement was performed in the same manner as in the first example except that the first ventilation resistance member 73 was removed. The results are shown in Table 1.

  As shown in FIG. 5 that graphically represents the results of Table 1 and Table 1, in Example 1 and Example 2, a predetermined differential pressure is formed between the first chamber 54 and the second chamber 64. On the other hand, in the reference example, almost no differential pressure is formed between the first chamber 54 and the second chamber 64. The replacement time of Example 1 and Example 2 was about 25% shorter than the reference example. It is considered that the differential pressure ΔPx formed between the first chamber 54 and the second chamber 64 is preferably 10 Pa or more.

12 ... Wafer 20 ... Hoop 24 ... Lid 20a ... Main opening 50, 150 ... EFEM
DESCRIPTION OF SYMBOLS 51 ... Introduction flow path 52 ... Gas introduction part 54 ... 1st chamber 55 ... 1st pressure gauge 56 ... Inlet 58 ... Connection position 60 ... Airflow formation part 61 ... Blower fan 64 ... 2nd chamber 65 ... 2nd pressure gauge 66 ... Oxygen concentration meter 68 ... Gas discharge part 69 ... Second ventilation resistance member 71 ... Exhaust flow path 72, 172 ... Differential pressure forming mechanism 73 ... First ventilation resistance member 174 ... Forced gas discharge mechanism 175 ... Exhaust fan 176 ... Damper 78 ... Third pressure gauge 80 ... Load port device 84 ... Mounting table 86 ... Door 90 ... Transfer robot

Claims (9)

A gas introduction part for introducing a replacement gas;
A first chamber provided with an inlet through which the replacement gas flows from the gas inlet;
A second chamber connected to the lower side of the first chamber and provided with a transfer robot for transferring wafers;
An airflow forming unit that forms a downward airflow from the first chamber toward the second chamber;
A gas discharge unit for discharging the gas in the second chamber from the second chamber;
A differential pressure forming mechanism that forms a predetermined pressure difference between the first chamber and the second chamber so that the pressure in the first chamber is higher than the pressure in the second chamber;
EFEM with   2. The differential pressure forming mechanism includes a first ventilation resistance member that is provided at a connection position connecting the first chamber and the second chamber and has a first ventilation resistance. EFEM described in 1. The air flow forming portion and the first ventilation resistance member are provided side by side in the connection position,
3. The EFEM according to claim 2, wherein the replacement gas passes through the air flow forming portion and the first ventilation resistance member and flows into the second chamber from the first chamber.   The gas discharge part has a second ventilation resistance member having a second ventilation resistance smaller than the first ventilation resistance, and the gas in the second chamber passes through the second ventilation resistance member. The EFEM according to claim 2 or 3, wherein the EFEM is discharged.   The said differential pressure | voltage formation mechanism has a forced gas discharge | emission mechanism which discharges | emits the gas of the said 2nd chamber forcibly from the said 2nd chamber, The Claim 1 characterized by the above-mentioned. EFEM. Introducing a replacement gas into the first chamber from the gas inlet through the inlet;
A gas introduction step for introducing the replacement gas into a second chamber connected to a lower portion of the first chamber and provided with a transfer robot for transferring a wafer;
Discharging the gas in the second chamber from the second chamber via a gas discharge portion;
EFEM gas replacement method comprising:
In the gas introduction step, the pressure in the first chamber is higher than the pressure in the second chamber. In the gas introduction step,
The replacement gas passes through a first ventilation resistance member provided at a connection position connecting the first chamber and the second chamber and having a first ventilation resistance, and the first chamber is transferred to the second chamber. By flowing in,
The EFEM gas replacement method according to claim 6, wherein the pressure in the first chamber is higher than the pressure in the second chamber. In the gas introduction step,
Driving a forced gas discharge mechanism for forcibly discharging the gas in the second chamber from the second chamber;
The EFEM gas replacement method according to claim 6, wherein the pressure in the first chamber is higher than the pressure in the second chamber.   The gas introduction step is started from a state where P1> P2> P3, where P1 is the pressure in the first chamber, P2 is the pressure in the second chamber, and P3 is the pressure in the installation environment of the EFEM. The EFEM gas replacement method according to claim 6.

Images