Abstract
Liquid-based cleaning is extensively used in the semiconductor and other industries affected by contamination for the removal of particulate contamination. One of the widely used wet-cleaning processes is the megasonic cleaning. The megasonics term is used in industry to refer to frequencies near 1 MHZ. Megasonic cleaning techniques used today in industry were first presented by RCA scientists [1,6,7]. McQueen [4,5] identified the effect of the acoustic boundary layer and its role in the removal of small particles at high frequency. Kashkoush, Busnaina et al [8–11] studied ultrasonic and megasonic particle removal, focusing on the effects of acoustic streaming. They showed that removal percentage increased with power. Their results also indicated different removal efficiencies for polystyrene latex (PSL), silica (SiO2) and silicon nitride (Si3 N4) particles. Megasonic cleaning using SC1 and SC2 chemistry has been shown to be very effective by Syverson, et. al. [12]. They also showed that the removal efficiency increased with power up to a 150 W (maximum power available). Wang et al [13] also showed that power had the greatest influence on the removal efficiency up to a maximum power available (150 W). These results are consistent with what was observed by Kashkoush, Busnaina and Gale [12,13]. However, Gale and Busnaina [14–17], using higher power megasonics up to 800 W, showed that the highest removal efficiency occurs at an optimum power (500–600 W) above which it decreases slightly. They also showed that megasonic input power has the greatest influence on particle removal efficiency as compared to solution temperature, both in water and in SC1 solution. They also showed that SC1 removes particles more efficiently than DI water, particularly at lower megasonic powers. But they also showed that it was still possible to achieve 100% removal in DI water under the proper conditions.