Until recently, solar energy has been considered as a promising regeneration energy source in the future. Solar cell wafer production involves ingot cutting, cleaning, and packaging processes. In this research, design, fabrication, and testing of a batch-type midsonic for cleaning solar cell wafers were carried out. To reduce the damage compared to conventional systems, we decided to use 400 kHz in a midsonic wave range, and we used far-field to obtain a more regular acoustic pressure. Finite element analysis with Ansys software predicted an anti-resonance frequency of 458 kHz for an ultrasonic waveguide, and the measured result of the fabricated system was 454 kHz with a 0.9% error. Acoustic pressures were measured, and the result confirmed regular and high distributions. Finally, cleaning tests were performed, and a 90% particle removal efficiency (PRE) was achieved at 900 W. Thus, the newly developed midsonic cleaning system can be considered to clean particles on solar cell wafers efficiently while preventing damage.

In this article, the megasonic cleaning system for cleaning micro/nano particles from flat panel display (FPD) surfaces was developed. A piezoelectric actuator and a waveguide were designed by finite element method (FEM) analysis. The calculated peak frequency value of the quartz waveguide was 1002 ㎑, which agreed well with the measured value of 1003 ㎑. The average acoustic pressure of the megasonic cleaning system was 43.1 ㎪, which is three times greater than that of the conventional type of 13.9 ㎪. Particle removal efficiency (PRE) tests were performed, and the cleaning efficiency of the developed system was proven to be 99%. The power consumption of the developed system was 64% lower than that of the commercial system. These results show that the developed megasonic cleaning system can be an effective solution in particle removing from FPD substrate with higher energy efficiency and lower chemical and ultra pure water (UPW) consumption.

In this article, a 20 kHz ultrasonic waveguide for nano-surface treatment was designed and manufactured. When designing the system, finite element analysis with ANSYS software was performed to find optimal dimensions of the waveguide, which can raise energy efficiency. Consequently an anti-resonance frequency of an Al waveguide with a piezoelectric actuator was 20 ㎑, which predicted the experimentally obtained value of 18 kHz well. For the assessment of the performance, Steel Use Stainless (SUS) 304 and chromium molybdenum steel (SCM) 435 specimens were tested. Cross-sectional microscopies of SUS304 were taken and they showed that the treated thickness was 30 ㎛. Additionally, hardness tests of SCM435 were done and the hardness before the process was 14.0 Rockwell Hardness?C scale (HRC) and after the process was 20.5 HRC, respectively, which means 46% increase. Considering these results, the developed ultrasonic system is thought to be effective in the nano-surface treatment process.

Improved far field type(improved type) megasonic applicable to the cleaning equipment of single wafer processing type has been developed. In this study, to improve the uniformity of acoustic pressure distribution(APD), we utilize far field with relatively uniform APD, piezoelectric ceramic with a triangle hole in its center to prevent standing wave resulted from radial mode, and reflected wave from the wall of waveguide. On the basis of these methods, two analysis models of improved type were designed to which piezoelectric ceramic of different shape of electrode attached, and APD were analyzed by means of finite element method, and then one of them was selected by analysis results, finally, the selected model was fabricated. Test results show that the fabricated is better in the uniformity of APD than the imported and the conventional, also the fabricated shows high particle removal efficiency of 92.3% using DI water alone as a cleaning solution.