N-2 TUNNEL WAFER TRANSPORT-SYSTEM

A wafer transport system has been developed for application to the nex t generation of ULSI manufacturing processes. In this system, various kinds of wafers ranging from 8 to 12 in. are floated on a gas film to be transported through an ultraclean N-2 gas environment with no solid contact. A sensor controls the movement of the transported wafer on t he control unit precisely and rapidly (i.e., a sensor instantly detect s and recognizes the configuration of the wafer and lets the wafer sto p, facing in the right direction. In this ultraclean N-2 gas environme nt, the wafer surface is free from particle contamination and growth o f native oxide. Furthermore, moving the electrostatic clamping device on the track, and the jet flow of ultraclean N-2 gas against the track , allows self-cleaning of the wafer transport track.