US Patent 7674695 Wafer cleaning system

An electromegasonic wafer cleaning system is disclosed that is extremely important, if not essential, in the fabrication of advanced microelectronic devices having a line width or feature size of from 0.05 to 0.10 micron. A unique synergistic combination is provided wherein piezoelectric transducer means are operated at a tolerable power level, such as from 1 to 2 watts per square centimeter, to minimize the risk of harm to the extremely delicate microcircuits and wherein the face of each wafer is negatively charged to a temperate voltage, such as from 5 to 20 volts, sufficient to cause effective removal of colloidal or sub 0.4-micron contaminant particles.