Equipment front end module gas recirculation
Disclosed are methods and apparatuses for recirculating gas in an equipment front end module (“EFEM”), including the ability to provide a gas during recirculation and control the gas flow, pressure, and composition of the environment in the EFEM during recirculation.
1. An apparatus comprising:
an equipment front end module (“EFEM”) having
a mini-environment,
an intake plenum fluidically connected to the mini-environment,
an EFEM gas outlet at the bottom of the EFEM and fluidically connected to the mini-environment, and
a fan unit configured to cause gas flowed from the intake plenum to move through the mini-environment;
an exhaust mechanism fluidically connected to the EFEM gas outlet and configured to be transitionable between at least a plurality of first open configurations and a plurality of second open configurations that have flow conductances less than the flow conductances of the plurality of first open configurations;
a recirculation duct that has a first end fluidically connected to the intake plenum and a second end fluidically connected to the mini-environment;
a first gas supply inlet fluidically connected to the intake plenum and configured to fluidically connect with a first gas supply;
a second gas supply inlet fluidically connected to the intake plenum and configured to fluidically connect with a second gas supply; and
a controller configured to:
(a) cause gas recirculation within the EFEM by causing gas to flow from the mini-environment, through the recirculation duct and the intake plenum, and back into the mini-environment,
(b) cause, during (a), a first gas to flow from the first gas supply and into the intake plenum at a first flowrate while the exhaust mechanism is in one or more of the first open configurations,
(c) cause, during (a) and after (b), the first gas to flow from the first gas supply and into the intake plenum at a second flowrate less than the first flowrate while the exhaust mechanism is in one or more of the second open configurations, and
(d) cause a second gas to flow from the second gas supply and into the intake plenum.
2. The apparatus of claim 1 , wherein the exhaust mechanism includes a throttle valve.
3. The apparatus of claim 1 , further comprising a pressure sensor configured to measure a pressure in the mini-environment, wherein:
the controller is further configured in (b) to adjust the configuration of the exhaust mechanism between the one or more first open configurations, based, at least in part, on the pressure of the mini-environment, and
the controller is further configured in (c) to adjust the configuration of the exhaust mechanism between the one or more second open configurations based, at least in part, on the pressure of the mini-environment.
4. The apparatus of claim 3 , wherein:
the controller is further configured to: (e) determine whether the pressure in the mini-environment is at, above, or below a first threshold pressure,
the controller is further configured in (b) to adjust the configuration of the exhaust mechanism based, at least in part, on the determination in (e), and
the controller is further configured in (c) to adjust the configuration of the exhaust mechanism based, at least in part, on the determination in (e).
5. The apparatus of claim 3 , wherein the controller is further configured to:
determine, during (b) and/or (c), whether a leak is present in the EFEM based, at least in part, on the pressure in the mini-environment and a flowrate of the first gas into the intake plenum, and
cause, based on the determination that a leak is present in the EFEM, the exhaust mechanism to transition to a third open configuration that has a flow conductance greater than or equal to a maximum flow conductance of the plurality of second open configurations, the flow of first gas flow from the first gas supply to the intake plenum to stop, and the second gas to flow from the second gas supply to the intake plenum.
6. The apparatus of claim 5 , wherein:
the exhaust mechanism includes a throttle valve and an exhaust bypass valve fluidically connected in parallel with the throttle valve, and
causing the exhaust mechanism to move to a third open configuration includes causing the exhaust bypass valve to transition to an open configuration.
7. The apparatus of claim 5 , further comprising a flowrate sensor configured to detect a flowrate of gas flowing through the first gas supply inlet.
8. The apparatus of claim 3 , wherein the controller is further configured to:
(f) cause the exhaust mechanism to move to a closed configuration,
(g) cause, after (f), gas to flow through the intake plenum and into the mini-environment at a third flowrate, and
(h) determine, during or after (g), whether a leak is present in the EFEM based, at least in part, on the pressure in the mini-environment and on the third flowrate.
9. The apparatus of claim 8 , wherein the controller is further configured to cause, based on a determination of the presence of a leak in the EFEM in (h), the exhaust mechanism to transition to a third open configuration that has a flow conductance greater than flow conductance of the plurality of second open configurations, and the second gas to flow from the second gas supply to the intake plenum.
10. The apparatus of claim 1 , wherein the controller is further configured to:
determine an outflow rate of gas from the mini-environment through the exhaust mechanism,
determine, during (b), whether a leak is present in the EFEM based, at least in part, on the first flowrate and the outflow rate of gas from the mini-environment,
determine, during (c), whether a leak is present in the EFEM based, at least in part, on the first flowrate and an outflow rate of gas from the mini-environment,
cause, based on a determination that a leak is present in the EFEM, one or more of:
an alarm to occur, and
the exhaust mechanism to transition to a third open configuration that has a flow conductance greater than a maximum flow conductance of the plurality of second open configurations, the flow of the first gas from the first gas supply to the intake plenum to stop, and the second gas to flow from the second gas supply to the intake plenum.
11. The apparatus of claim 10 , wherein the determination of the outflow rate of gas from the mini-environment is based on one or more of: the configuration of the exhaust mechanism, a pressure of the exhaust mechanism, and a flowmeter.
12. The apparatus of claim 1 , further comprising:
a first mass flow controller fluidically connected to the first gas supply inlet and configured to fluidically connect with the first gas supply,
a second mass flow controller fluidically connected to the first gas supply inlet and configured to fluidically connect with the first gas supply, wherein:
the controller is further configured in (b) to cause the first mass flow controller to flow the first gas into the intake plenum at the first flowrate, and
the controller is further configured in (c) to cause the second mass flow controller to flow the first gas into the intake plenum at the second flowrate.
13. The apparatus of claim 1 , further comprising:
an oxygen sensor configured to measure an oxygen level in the mini-environment, and
a moisture sensor configured to measure a moisture level in the mini-environment, wherein:
the controller is further configured in (c) to adjust the flowrate of the first gas based, at least in part, on the oxygen level and the moisture level of the mini-environment.
14. The apparatus of claim 13 , further comprising a pressure sensor configured to measure a pressure in the mini-environment, wherein:
the controller is further configured in (b) to adjust the configuration of the exhaust mechanism between the one or more first open configurations, based, at least in part, on one or more of: the pressure of the mini-environment, the oxygen level, and the moisture level of the mini-environment, and
the controller is further configured in (c) to adjust the configuration of the exhaust mechanism between the one or more second open configurations based, at least in part, on one or more of: the pressure of the mini-environment, the oxygen level, and the moisture level of the mini-environment.
15. The apparatus of claim 1 , further comprising:
a loadport mounting hole located on the EFEM, and
a latch that has a housing and a piston, and is configured to position the piston in a retracted position and an extended position, wherein:
the latch is mounted to the EFEM such that when the piston is in the extended position the piston covers at least a portion of the loadport mounting hole when viewed along the center axis of the load port mounting hole, and when the piston is in the retracted position the piston does not cover the loadport mounting hole when viewed along the center axis of the load port mounting hole, and
wherein the controller is further configured to cause the piston to be in the extended position during (a), (b), (c), and (d).
16. The apparatus of claim 15 , further comprising an oxygen sensor configured to measure an oxygen level in the mini-environment, wherein:
the controller is further configured to cause, based on a determination that the oxygen level in the mini-environment is below a second threshold value, the piston to be in the extended position.
17. The apparatus of claim 15 , further comprising a loadport connected to the EFEM, wherein:
a bolt extends through a hole of the loadport and through the loadport mounting hole to thereby connect the loadport to the EFEM,
when the piston is in the extended position the piston covers at least a portion of the bolt when viewed along the center axis of the bolt, and
when the piston is in the retracted position the piston does not cover the bolt when viewed along the center axis of the bolt.
18. The apparatus of claim 1 , wherein the controller is further configured to:
cause, during (b) or (c), the exhaust mechanism to transition to a third open configuration that has a flow conductance greater than flow conductance of the plurality of second open configurations, the flow of the first gas from the first gas supply to the intake plenum to stop, and the second gas to flow from the second gas supply to the intake plenum.