Controlled environment tightly closed vessel and machine interface

PURPOSE: To move contents in a first chamber to a second chamber without exposing the contents to the outside air, by evacuating gas from an interface volume, moving the wall of a second chamber into an area inside the second chamber, and moving the wall of a first chamber and contents in the first chamber into the area inside the second chamber. CONSTITUTION: A wafer carrier 42 is arranged on the upper wall 20 of a buffer chamber 14. An interface chamber 68 is exhausted by using a pump via an interface port 70. When the pressure in the interface chamber 68 becomes nearly equal to carrier pressure, the upper wall 20 of the buffer chamber 14 is made to descend by an elevator mechanism 22. As a result, a bottom cover member 46 of the wafer carrier 42 is made to descend in the buffer chamber 14. It becomes possible for a semiconductor wafer 52 to perform access for working.