Dual arm with opposed dual end effectors and no vertical wafer overlap

A method comprising:

• providing a drive;
• and
• connecting a movable arm assembly to the drive, where the movable arm assembly comprises a first arm and a second arm, where the first arm comprises a first upper arm, a first forearm and a first end effector, where the second arm comprises a second upper arm, a second forearm and a second end effector, where the first end effector comprises at least two first upper substrate holding areas, where the second end effector comprises at least two second lower substrate holding areas, where the drive and the movable arm assembly are configured to prevent the movable arm assembly from passing over top sides of substrates located on the second lower substrate holding areas of the second end effector.

A method comprising:

• locating substrates on substrate holding areas of a first end effector and a second end effector, where the first and second end effectors are part of a movable arm assembly connected to a drive, where the movable arm assembly comprises a first arm and a second arm, where the first arm comprises a first upper arm, a first forearm and the first end effector, where the second arm comprises a second upper arm, a second forearm and the second end effector, where the first end effector comprises at least two first upper substrate holding areas, where the second end effector comprises at least two second lower substrate holding areas;
• and
• moving the first and second arms to move the substrates on the first and second end effectors from a retracted position to an extended position, where the drive and the movable arm assembly are configured to prevent the movable arm assembly from passing over top sides of the substrates located on the second substrate holding areas of the second end effector at all locations of the movable arms including when the end effectors are at their respective retracted positions and respective extended positions.

A non-transitory program storage device readable by a machine, tangibly embodying a program of instructions executable by the machine for performing operations, the operations comprising:

• locating substrates on substrate holding areas of a first end effector and a second end effector, where the first and second end effectors are part of a movable arm assembly connected to a drive, where the movable arm assembly comprises a first arm and a second arm, where the first arm comprises a first upper arm, a first forearm and the first end effector, where the second arm comprises a second upper arm, a second forearm and the second end effector, where the first end effector comprises at least two first upper substrate holding areas, where the second end effector comprises at least two second lower substrate holding areas;
• and
• controlling the drive to move the first and second arms to move the substrates on the first and second end effectors from a retracted position to an extended position, where the drive is controlled and the movable arm assembly is configured to prevent the movable arm assembly from passing over top sides of the substrates located on the second lower substrate holding areas of the second end effector at all locations of the movable arms including when the end effectors are at their respective retracted positions and respective extended positions.