Electrostatic manipulator for 300-mm wafers

This paper presents the developments in contactless mechanisms for use in the manufacturing process of semiconductor devices, an electrostatic manipulator for a 300-mm silicon wafer. The novel aspects of this manipulator are that not only can it directly levitate a wafer via electrostatic forces and then transport it by controlling the movement of electrodes, but it can also keep the net surface potential of the wafer near zero volts. As a result, if greatly reduces the contamination of the wafer surface by dust particles. In this paper, a brief review of the basic principle of electrostatic levitation is presented. It is followed by a description of the structure of the manipulator, including the electrodes pattern, position and orientation control method, voltage-application pattern, motion control of the levitation unit, and the operational procedure. Experimental results which demonstrate completely contactless handling of a 300-mm silicon wafer are also presented.