A wafer-retaining cushion sheet (5) has a wafer suction-adhering surface (5C) formed on a surface thereof, which adheres by suction to a semiconductor wafer (W). A wafer tray (1) is provided with a plurality of bottom openings (17) opening to the reverse side of the wafer-retaining cushion sheet (5), an air chamber (16) communicating with the bottom openings, and an air inlet (11) for supplying pressurized air into the air chamber (16) from the outside. Consequently, when pressurized air is supplied into the air chamber (16) through the air inlet (11) to increase the air pressure in the air chamber (16), the wafer-retaining cushion sheet (5) is elastically deformed into an inflated form at regions facing the bottom openings (17), thus causing separation between the semiconductor wafer (W) and at least a part of the wafer suction-adhering surface (5C) of the wafer-retaining cushion sheet (5).

A wafer storage container has a container body and a lid. The container body has lid support inserts in a lid receptacle, and the lid has corner inserts for contact with the lid support inserts to support the lid. A supporting member is attached to the container body. The supporting member includes a base plate portion, side plates extending from the base plate portion, and a handle on each side plate for lifting the container body. The thin plate supporting member has contacting portions to support the thin plates, supporting members which elastically support the contacting portions, and a base support bar to support the supporting portions. The tip end of each supporting portion contacts a support stage, and elastically supports the contacting portions from both sides.

A double-seal mechanism is provided on a cover member for sealing closed a container main body. The double-seal mechanism includes an inner seal piece that seals an interior of the container main body and is positioned between an inner seal reception section of a flange of the container main body and a seal pressing section of the cover. An outer seal piece forms a second seal between the container main body and the periphery of the cover member. The inner seal piece has a rounded distal end fitted into a fitting groove in the flange. A cover member fixing unit of the cover member includes a latch shaft that is linearly projected from and retracted, a latch roller attached to a tip end of the latch shaft, and a crank mechanism that linearly projects and retracts the latch shaft as the crank mechanism rotates. The latch roller travels along an inclined retracting surface on the container main body which forces the cover member inward into sealing engagement with the container main body.

A wafer storage container has a container body and a lid. The container body has lid support inserts in a lid receptacle, and the lid has corner inserts for contact with the lid support inserts to support the lid. A supporting member is attached to the container body. The supporting member includes a base plate portion, side plates extending from the base plate portion, and a handle on each side plate for lifting the container body. The thin plate supporting member has contacting portions to support the thin plates, supporting members which elastically support the contacting portions, and a base support bar to support the supporting portions. The tip end of each supporting portion contacts a support stage, and elastically supports the contacting portions from both sides.

A wafer cassette comprises a case body and an adapter that supports substrates. There are adapters of various types corresponding to the size of the substrates to be supported. The case body and the adapter of any type are united in a manner such that fitting portions of the case body are fitted individually in fitting holes of the adapter.