Electrochemical investigations of stable cavitation from bubbles generated during reduction of water

• An electrochemical method to generate microstreaming near conducting surfaces.
• Chronoamerometry to characterize behavior of stable bubbles.
• At 10% duty cycle, resonating bubbles exhibited high amplitude oscillations.
• At duty cycles of 50% and 100%, the overall current was lower than that at 10%.
• Method very useful for megasonic cleaning of surfaces in microelectronics industry.

Megasonic cleaning is traditionally used for removal of particles from wafer surfaces in semiconductor industry. With the advancement of technology node, the major challenge associated with megasonic cleaning is to be able to achieve high cleaning efficiency without causing damage to fragile features. In this paper, a method based on electrochemistry has been developed that allows controlled formation and growth of a hydrogen bubbles close to a solid surface immersed in an aqueous solution irradiated with ∼1 MHz sound field. It has been shown that significant microstreaming from resonating size bubble can be induced by proper choice of transducer duty cycle. This method has the potential to significantly improve the performance of megasonic cleaning technology through generation of local microstreaming, interfacial and pressure gradient forces in close vicinity of conductive surfaces on wafers without affecting the transient cavitation responsible for feature damage.