Fundamental characteristics of electrostatic wafer chuck with insulating sealant

In the semiconductor industry, many manufacturing processes, such as CVD or dry etching, are performed in vacuum condition. The electrostatic wafer chuck is the most preferable handling method under such circumstances. It enables retention of a wafer flat and enhanced heat transfer through the whole surface area because the wafer can firmly contact with the chuck. We have investigated the fundamental study of an electrostatic chuck with comb type electrodes and a thin dielectric film. In order to remove the air gap between them, silicone oil is used as a filler to prevent breakdown. The experimental results proved the potential to use the electrostatic chuck for silicon wafer handling. There, however, is a problem which comes from using silicone oil as an insulating filler. The thin dielectric film is easily deformed by tension when the object starts moving. In this report experimental results of the electrostatic wafer chuck are shown when insulating sealant, instead of silicone oil, is used. The electrostatic force acting on the 4 inch silicon wafer is examined with several types of sealant and dielectric films. The electrostatic force increased with the square of the applied voltage for lower voltage and gradually saturated at higher voltage, and the maximum force obtained was approximately 30 N.