PURPOSE: To eliminate the rubging of a wafer with its pushing, and to damage no wafer, nor dusting, even in case of there being the misregistrations of wafer and gripper, in the wafer holding, by providing a piezoelectric element for opening and closing a claw and a detection means which detects the holding force of the wafer and claw.
CONSTITUTION: The displacements of piezoelectric elements 12-15 are transmitted to claws 17, 18, the contact force with two claws 17, 18 and a wafer 1 is detected simultaneously, the contact force is increased in the range that the wafer 1 is not moved, with the claw of a weaker contact force being displaced further, the contact force is increased with this being performed alternately, and the wafer 1 is held. Consequently, the wafer 1 can be held, without moving the wafer 1.
SUZUKI TAKAMICHI
HAMADA TOYOHIDE
AKAIWA MASAYASU
DAIROKU NORIYUKI
