Wafer processing system with dual wafer robots capable of asynchronous motion

A robot assembly for transferring substrates, comprising:

• a central tube assembly oriented along a central axis and having an inner surface that forms part of a first enclosure at a first pressure, and an outer surface that forms part of a second enclosure at a second pressure, said second pressure being generally different from said first pressure, said central tube assembly supporting stator assemblies of first and second brushless motor assemblies within the first enclosure;
• a substrate transfer plane, perpendicular to the central axis of said central tube assembly;
• and
• a first transfer robot including:
• a first rotor assembly, configured to rotate parallel to said transfer plane concentrically with said outer surface of said central tube assembly, said first rotor assembly including a rotor portion of the first brushless motor assembly located within the second enclosure;
• a second rotor assembly, configured to rotate parallel to said transfer plane concentrically with said outer surface of said central tube assembly and positioned above said first rotor assembly, said second rotor assembly including a rotor portion of the second brushless motor assembly located within the second enclosure;
• a first support arm, rigidly attached to said first rotor assembly and extending radially outwards from said first rotor assembly;
• a first slider, supported by said first support arm and configured to move in a generally radial direction along a length of said first support arm;
• a first end effector, supported by said first slider and configured to move in a generally radial direction along a length of said first slider;
• a first inner actuator arm, having an inner end and an outer end, said inner end being rigidly attached to said second rotor assembly;
• and
• a first outer actuator arm, having a first end and a second end, wherein said first end is coupled to said outer end of said first inner actuator arm by a first bearing, said first bearing enabling said first outer actuator arm to rotate around an axis of said first bearing parallel to said transfer plane;
• and said second end is coupled to said first end effector by a second bearing, said second bearing enabling said first outer actuator arm to rotate around an axis of said second bearing parallel to said transfer plane;
• wherein a motor control system is configured for rotating the first rotor assembly and the second rotor assembly in the same direction and speed to produce a first axis motion for both the first and second rotor assemblies, and wherein the motor control system is configured for rotating the first rotor assembly and the second rotor assembly at different speeds and directions to produce a second axis motion for both the first and second rotor assemblies.