Patent ID: 8156950

Claim:
A megasonic cleaning system for cleaning a microelectronic substrate, the system comprising: a process tank for containing a liquid; a first transducer positioned within the process tank that produces a first sonic field in the liquid, the first sonic field having a first wave approach angle relative to a position in which a surface of a microelectronic substrate is held within the process tank; a second transducer positioned within the process tank that produces a second sonic field in the liquid, the second sonic field having a second wave approach angle relative to the surface of the substrate, the first and second wave approach angles having a difference of 180 degrees; wherein the first transducer initiates cavitation events in a bulk portion of the liquid proximate the surface of the substrate via the first sonic field, wherein the second transducer controls an interface of fluid friction between the substrate and the bulk portion of the liquid via the second sonic field, and wherein the first transducer oscillates at a first frequency to produce the first sonic field and the second transducer oscillates at a second frequency greater than the first frequency to produce the second sonic field; and a controller operable coupled with the first and second transducers, the controller including a processor and a memory storing processing instructions for at least (1) operating the first transducer at the first frequency that initiates cavitation events and (2) operating the second transducer at the second frequency that controls the interface of fluid friction by regulation of the boundary layer thickness.