Elevator drive mechanism.

摘要

In an electron beam wafer writing vacuum chamber, an elevator drive shaft (98) is air pressure counterbalanced and dampened under varying load and system pressure conditions by applying required air pressure to an appropriate side of a piston (137) moving with the drive shaft. Air pressure counterbalancing load forces minimize the actuating forces required to drive the elevator, substantially minimizing vibratory shock and distortion to the electron beam writing system. This permits electron beam writing on one wafer simultaneously with a load/unload operation of a second semiconductor wafer.