Image Number 7 for United States Patent #6481956.
A method of transferring semi-conductor substrates from a first location to a second location. The first and second locations are adapted to hold a plurality of the substrates in individual support area. The method comprises use of a transfer mechanism with two substrate holding end effectors which each have support areas adapted to individually support different maximum numbers of substrates thereon. The substrates are transferred from the first location to the second location with the first end effector and, when empty individual support areas in the second location or substrates at the first location are less than the maximum number of support areas on the first end effector, transferring substrates from the first location to the second location with use of the second end effector.