Patent ID: 8657352

Claim:
A method for use with a device that comprises (i) a robotic arm that includes an end effector, the end effector including at least two prongs designed to hold a substrate carrier and also including a pushing member that can move independently of said at least two prongs, wherein the pushing member is configured to exert force against the substrate carrier while said at least two prongs are retracted from the substrate carrier, thereby preventing the substrate carrier from being retracted while said at least two prongs are retracted and (ii) at least one motor for moving the pushing member and said at least two prongs, the method comprising: (a) bringing, by using the end effector, a selected substrate carrier to a desired position, the prongs holding the selected carrier while the selected carrier is being moved; (b) moving the pushing member towards the selected carrier, the pushing member exerting force against the selected carrier; (c) moving the prongs away from the selected carrier, while the pushing member continues to exert force against the selected carrier and thereby maintain the desired position of the selected carrier; and (d) retracting the pushing member so that it no longer contacts the selected carrier, wherein said steps (a), (b), (c), and (d) are carried out in turn.