Patent ID: 7925377

Claim:
A method of transferring a substrate in a cluster tool, comprising: inserting at least one substrate into each of two or more vertically stacked processing chambers in a first processing rack using a first robot; removing a substrate from at least two of the two or more vertically stacked processing chambers in the first rack substantially simultaneously using a second robot that comprises at least one moveable arm having at least one substrate supporting surface; substantially simultaneously transferring the substrates to two or more vertically stacked processing chambers in a second processing rack using the second robot, wherein simultaneously transferring comprises moving the second robot a distance in a horizontal direction using a horizontal motion assembly; substantially simultaneously depositing the substrates in at least two of the two or more vertically stacked processing chambers in the second processing rack using the second robot; creating a first list of one or more command tasks for the first robot based on a user defined processing sequence; creating a second list of one or more command tasks for the second robot based on the user defined processing sequence; storing one or more command tasks for the first robot and the second robot in a memory of a controller; reviewing the first list and the second list to calculate an imbalance in work load between the first and second robots; and moving at least one of the one or more command tasks from the first list to the second list to balance the work load.