A gate valve (1) is constructed for the simultaneous blocking or clearing of two rectangular passage openings (8,9) of two chamber walls (4,5) that are provided between two vacuum chambers (1,3) and aligned with one another. To this end, it has two valve plates (20, 21), which are a component of a slider (15), which is situated so that it can move with play from a position clearing the passage openings (8,9) to a position which closes the passage openings (8,9). To move the valve plates (20,21) to the closing setting against the passage openings (8,9) on the slider (15), at least one lifting element (24), which is acted on by pressure, is provided.

A gap is defined between an inner region of an end face of a first container member of a container and an inner region of an abutting portion of a second container member, the inner regions being situated inside a seal member. The respective inner regions of the end face of the first container member and the abutting portion of the second container member, which are situated inside the seal member, are prevented from coming into contact with each other when the interior of the container is decompressed. Even though the second container member is bent inward by atmospheric pressure when the container is decompressed to a predetermined degree of vacuum, therefore, the abutting portion thereof cannot come into contact with the inner edge of the end face of the first container member. Thus, if decompression and exposure to atmospheric pressure are repeated to bend the container member repeatedly, there is no possibility of the inner edge portion of the end face of the first container member being separated or rubbed off to produce dust.

There is a gap between the respective inner regions of the end face of the cylindrical side wall and the abutting portion of the top plate, which are situated inside the seal member. Even though the top plate is bent inward by atmospheric pressure when the container is decompressed to a predetermined degree of vacuum, therefore, the abutting portion thereof cannot come into contact with the inner edge of the end face of the cylindrical side wall. Thus, if decompression and exposure to atmospheric pressure are repeated to bend the cylindrical side wall repeatedly, there is no possibility of the inner edge portion of the end face of the cylindrical side wall being separated or rubbed off to produce dust. Moreover, the cylindrical side wall and top plate are joined together in the region outside the seal member. If dust is produced by the contact between the cylindrical side wall and top plate at their junctions outside the seal member, therefore, it is prevented from entering the container by the seal member. Thus, a clean atmosphere in the container cannot be contaminated by the dust.

An apparatus for wet cleaning or etching of flat substrates comprising a tank with an inlet opening and outlet opening for said substrates. Said tank contains a cleaning liquid and is installed in a gaseous environment. At least one of the openings is a slice in a sidewall of the tank and is present below the liquid-surface. In the tank there may be a portion above the liquid filled with a gas with a pressure being lower than the pressure within said environment. The method comprises the step of transferring a substrate through the cleaning or etching liquid at a level underneath the surface of said liquid making use of said apparatus.

An evacuable wafer processing machine includes a load-lock station, a wafer transfer station separated from the load-lock station by means of a gate-valve and a wafer coating station. Wafers contained within an evacuated wafer box are loaded into the load-lock station. The load-lock station is then closed and evacuated. A pair of pneumatically-operated plungers operable within the load-lock station, pick-up and remove the covers from the wafer box. The gate-valve is opened and the box of wafers is transferred into the wafer transfer station. Within the wafer transfer station, a wafer transfer blade passes vertically through the wafer box to serially transfer the wafers between the transfer station and the wafer coating station. After all the wafers have been coated, the wafer box is transferred through the open gate-valve into the load-lock station, the gate-valve closed and the covers replaced on the wafer box. The load-lock station is then let-up to atmosphere, thereby forcing the covers into gas-tight sealing engagement with the storage box and the storage box is removed from the loadlock station. The actuator for actuating the wafer transfer blade includes an elongated, hollow, cylindrical member containing therein a piston forced to and fro within the cylinder by pneumatics. The piston is magnetically coupled through the walls of the cylinder to a slider having the wafer transfer blade affixed thereto.