Fundamental study of an electrostatic chuck for silicon wafer handling

A mechanical holding system of a wafer might cause a serious problem in the semiconductor industry. Electrostatic wafer handling might be one of the possible solutions for such a problem. We have investigated the attractive force on a silicon wafer by using the electrostatic chuck which consists of interdigitated electrodes and a dielectric thin film. Electrostatic attractive force increases, as the applied voltage increases, and with thinner dielectric layer. The narrower width and spacing of interdigitated electrodes, the stronger electrostatic force is obtained. When the 1 mm width interdigitated electrodes and 50 /spl mu/m thick film are used, the strongest force obtained was about 17 N in the vertical direction at 3.5 kV, for a 4" silicone wafer. When DC high voltage is used, some residual force remains even after the applied voltage is removed. This was overcome by using variable frequency AC high voltage.