Holder mechanism for simultaneously tilting and rotating a wafer cassette

Abstract

A holder mechanism tilts and rotates a vertically oriented wafer-loaded cassette for proper presentation in a horizontal orientation to the robotic arm of a workstation. The mechanism includes a cassette holder, a support member, and a motor. The cassette holder has first and second supports that define orthogonal first and second planes. In two embodiments, the support member connects the cassette holder to the motor shaft and, as the motor shaft rotates, the cassette holder is rotated about a single pivot axis that is oblique to the first and second planes. This rotation tilts a cassette placed in the holder through a tilt angle of about 45.degree. to 90.degree., and simultaneous rotates the cassette through an angle .theta. about the vertical axis. The support member shape determines whether tilting and rotation is away from or toward the motor, and also determines the angle of rotation .theta. and the tilt angle. After workstation processing, the motor rotates in the opposite direction to produce a counter-tilt and counter-rotation that returns the cassette to a vertical orientation. In a third embodiment, the support member is coupled to a horizontal shaft that is coupled to a worm gear assembly. Vertical motor shaft rotation rotates the horizontal shaft through a tilt angle, and simultaneously rotates the cassette holder through the rotation angle .theta..