Newly Designed Electrostatic Wafer Chuck Resulting in Less Particle Contamination on Back Side of Wafers

Electrostatic wafer chucks are frequently used for wafer-handling in the vacuum systems of semiconductor manufacturing equipment, but the particles that they generate and that adhere to the back side of the wafer have recently become a serious problem. Chucks having a small area of contact with the wafer are usually effective in reducing the particle adhesion, but the chucking force is also smaller. The experiments described here evaluated the performance of an electrostatic wafer chuck that has a small area of contact with the wafer and that has a gap small enough to maintain the electrostatic chucking force. Particle adhesion was reduced by the smaller area of contact but was also strongly dependent on the polarity of the voltage applied to the chuck.