Ic waper carrier sealed from ambient atmosphere during transportation from one process to the next

Abstract

A wafer carrying structure is provided that allows more efficient operation of the opening and closing mechanisms. More specifically, the wafer carrier includes pressure relief structures that provide appropriate pressure equalization during the opening and closing operations of the wafer carrier. This allows doors on the wafer to be more easily opened and closed while also providing significant environmental isolation for the wafers during transport operations. Relief structures specifically designed to remain closed except for those brief periods of time where pressure relief is necessary to equalize pressure during opening and closing of the carrier.

1 . A wafer carrier for protecting wafers during transportation from one step of a manufacturing process to another, comprising:
 a carrier structure for capturing a wafer and holding the wafer in a controlled position during transportation, said carrier structure comprising:   a housing substantially surrounding the carrier structure, the housing capable of enclosing the carrier structure and the wafer, the housing further having an opening to allow access to the wafer and having vent openings to allow airflow into and from an interior of the housing; and   a door mechanism cooperating with the housing to form a fluid tight seal when attached thereto, the door being removable to expose access to the housing opening, wherein the door is attached to the housing with a consistent amount of force when establishing the fluid tight seal, and wherein the door is removed from the housing with the consistent amount of force when disestablishing the fluid tight seal; and   a plurality of relief valves, wherein each of the plurality of relief valves is a poppet valve including:
 an outer shell configured to tightly fit within the vent openings, 
 a movable plate having a first surface thereof exposed to air pressure changes within the housing caused by opening and closing of the door mechanism, 
 a spring positioned within the outer shell and in contact with the movable plate on a side opposite the first surface, and 
 a retainer for holding the movable plate in position, 
 wherein the retainer is coupled to the outer shell in an airtight manner and contact between the movable plate and the retainer forms an airtight seal when the valve is in a closed position, the spring of each of said plurality of relief valves being calibrated such that said relief valve is configured to generally remain in the closed position, but also allowing for movement to an open position exclusively for relieving the air pressure changes within the housing caused by the opening and closing of the door mechanism, 
 the plurality of relief valves thereby allowing airflow into the interior of the housing responsive to air pressure changes caused by the opening of the door mechanism and allowing airflow to escape from the interior of the housing responsive to air pressure changes caused by the closing of the door mechanism. 
   
   
   
       2 . The wafer carrier of  claim 1 , wherein the plurality of relief valves comprises a first relief valve specifically configured to relieve an air pressure vacuum generated within the carrier caused by the opening of the door mechanism, and a second relief valve specifically configured to relieve an air pressure increase generated within the carrier caused by the closing of the door mechanism. 
   
   
       3 . The wafer carrier of  claim 1 , wherein each of the plurality of relief valves further includes an adjustment structure for adjusting the calibration of the relief valve. 
   
   
       4 . The wafer carrier of  claim 1 , wherein each of the plurality of relief valves further includes a filter structure to provide air filtering while the relief valve is in the open position.