This study has been based on the examination of the characterization of ring-type lead zirconate titanate (PZT) ceramics for high-intensity focused ultrasonic dispersion system. The ring-type PZT ceramics were fabricated by the powder molding method. The mechanical properties, dielectric constant, and microstructure of the ceramics were investigated. Consequently, the density of the ceramics was increased with increasing forming pressure while the density of ceramics that were sintered at 1350 °C was decreased due to over-sintering. Furthermore, the mechanical properties were excellent at the higher forming pressure. The dielectric property of the ring-type PZT ceramics was not clearly influenced by the manufacturing and sintering conditions. The abnormal grain growth of the ceramics, however, could be prevented by a lower heating rate in addition to reducing the porosity.

T type megasonic waveguide was analyzed by finite element method (FEM), acoustic pressure measurements and particle removal efficiency for the single wafer cleaning application. Compared to conventional longitudinal waves, a transverse waves were generated in a T type waveguide. Not like longitudinal waves, transverse waves showed changes of direction and phase which increased the cleaning efficiency.

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A near-field megasonic system for cleaning semiconductors was designed and fabricated. For the design of the near-field megasonic system, an impedance characteristic of a quartz megasonic waveguide with the piezoelectric actuator was analyzed using a finite element method (FEM). The analysis result showed that the anti-resonance frequency of the system was 982 kHz, which agreed well with the measured value of 988 kHz. The performance of the developed system was assessed by measuring acoustic pressures and comparing the maximim values of them with a conventional megasonic system. As a result, the maximim acoustic pressure of the developed system was decreased by 46.2% compared to the commercial system. Finally, the particle removal efficiency (PRE) test was performed and the obtained PRE was 90.8%. Theses results explain that the developed megasonic has an improved uniformity of the acoustic pressures, which can raise the energy efficiency of the system and lowering the consumption of chemical and ultra pure water (UPW).

In case of a boiler, scale is made on the surface of tube by the chemical reactions of Ca and Mg ions contained in the water and heat transfer rate is reduced because of the increment of heat resistance. Thus, it brings about the reduced energy transfer efficiency and also environmental pollution due to the use of chemicals for scale removing. In this paper, we have first investigated the effects of irradiated ultrasonic wave on water with impurities in a beaker. The experiments show that exposed water is less transparent and has finer particles as compared to unexposed water. This means that the ultrasound shakes water in the beaker and breaks out particles, and so broken fine particles are suspend in the state of less precipitation. Second, the laboratory experiment with an exposed sample in the similar condition to the boiler shows better scale prevention effects as compared to the unexposed one. And also 20 kHz ultrasound represents about 3 times better scale prevention effects than 40 kHz. Finally, scale prevention experiments in the real small boiler tell us exposed sample results in 3659% less scale formation than an unexposed one.