Transfer system in a clean room

A transfer system for transferring a pod in a clean room, in which the pod is adapted to contain a wafer cassette, comprising:

• at least one pair of ARMs, disposed adjacent to a semiconductor processing apparatus for transferring wafers, loaded in the wafer cassette, into and out of the semiconductor processing apparatus;
• a transfer tube disposed near the ARMs;
• a vehicle adapted to carry the pod and adapted to move within the transfer tube;
• evacuation means for evacuating the transfer tube to produce a negative pressure within the transfer tube so that the vehicle is moved along an axis of the transfer tube due to the negative pressure;
• and
• at least one pair of conveying means for conveying the vehicle between the transfer tube and respective ARM's, each conveying means includes:
• a first tubular station member having a bottom wall, jointed at one end thereof to the transfer tube for communication with the transfer tube and closed at the other end, the first station member extending substantially horizontally to a position near a corresponding ARM;
• delivering means for delivering the vehicle between the first station member and the corresponding ARM;
• and communicating means for communicating the first station member to the evacuation means to produce another negative pressure within the first station member for moving the vehicle within the first station member from the transfer tube to the delivering means, wherein the transfer tube includes stopping means for stopping the vehicle within the transfer tube in front of the one end of the first station member for introducing the vehicle into the first station member, and
• the first station member includes a bottom closure means, mounted to the bottom wall at the other end thereof, for allowing the vehicle to enter into and exit from the first station member, wherein the corresponding ARM is located just below the bottom closure means, and wherein the delivering means comprises vertically moving the vehicle between the first station member and the corresponding ARM through the bottom closure means.