Design, fabrication and performance test of a 3 MHz megasonic waveguide for nano-particle cleaning

In this article, a 3 MHz near-field megasonic waveguide for nano-particle control was developed. In the design process, an impedance graph of the megasonic system with the piezoelectric actuator was obtained by analysis using finite element method (FEM) software ANSYS. After analysis, the maximum value of the anti-resonance frequency was obtained as 2997 kHz, which coincided with the design value. Additionally, acoustic pressure distribution of the system was predicted by FEM. After fabricating the waveguide using the analysis results, the system performance was assessed by measuring acoustic pressures. The maximum value and standard deviation of measured data were analyzed and compared with a conventional megasonic system to evaluate the system performance. As a result, the maximum value was decreased by 35.6%, and the standard deviation of the developed system was decreased by 10.4% compared to the conventional type both at the same average acoustic pressure. And to evaluate cleaning ability, the particle removal efficiency (PRE) test was performed with 80 nm particles. The PRE result showed that the system cleaned 93.1% particles. Considering these results, the developed megasonic system is thought to have an improved cleaning ability with more uniform acoustic pressures. These imply that the megasonic system can be applied to nano-particle cleaning process with higher energy efficiency and lower consumption of chemical and ultra pure water (UPW).