Patent ID: 8310131

Claim:
A megasonic processing method comprising: providing two or more piezoelectric transducers, each having a fundamental resonant frequency of at least 300 KHz, wherein the fundamental resonant frequency of one piezoelectric transducer defines a maximum fundamental resonant frequency and the fundamental resonant frequency of another piezoelectric transducer defines a minimum fundamental resonant frequency; providing a tank adapted to contain fluid wherein said two or more transducers are coupled to the tank and adapted for providing vibrations to the tank and its contents; and generating and simultaneously supplying a driving signal to the transducers, wherein the driving signal has a frequency that sweeps throughout a frequency range that ranges from a maximum drive frequency that exceeds the maximum fundamental resonant frequency and a minimum drive frequency that is less than the minimum fundamental resonant frequency, further including determining the maximum fundamental resonant frequency and minimum fundamental resonant frequency of the transducers and defining the maximum drive frequency and minimum drive frequency such that the amount that the maximum drive frequency exceeds the maximum fundamental resonant frequency is substantially equal to the amount that the minimum drive frequency is less than the minimum fundamental resonant frequency.